Water Scarcity and Ways to Reduce the impact - vários autores (2019)

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Applied Environmental Science and Engineering for a Sustainable Future

Muthu Pannirselvam · Li Shu Gregory Griffin · Ligy Philip Ashok Natarajan · Sajid Hussain Editors

Water Scarcity and Ways to Reduce the Impact Management Strategies and Technologies for Zero Liquid Discharge and Future Smart Cities

Applied Environmental Science and Engineering for a Sustainable Future Series editors Jega V. Jegatheesan, RMIT University, Melbourne, Australia Li Shu, LJS Environment, Melbourne, Australia Piet Lens, UNESCO-IHE Institute for Water Education, Delft, The Netherlands Chart Chiemchaisri, Kasetsart University, Bangkok, Thailand

Applied Environmental Science and Engineering for a Sustainable Future (AESE) series covers a variety of environmental issues and how they could be solved through innovations in science and engineering. Our societies thrive on the advancements in science and technology which pave the way for better standard of living. The adverse effect of such improvements is the deterioration of the environment. Thus, better catchment management in order to sustainably manage all types of resources (including water, minerals and others) is of paramount importance. Water and wastewater treatment and reuse, solid and hazardous waste management, industrial waste minimisation, soil restoration and agriculture as well as myriad of other topics needs better understanding and application. This book series aims at fulfilling such a task in coming years.

More information about this series at http://www.springer.com/series/13085

Muthu Pannirselvam Li Shu Gregory Griffin Ligy Philip Ashok Natarajan Sajid Hussain •

•

•

Editors

Water Scarcity and Ways to Reduce the Impact Management Strategies and Technologies for Zero Liquid Discharge and Future Smart Cities

123

Editors Muthu Pannirselvam RMIT University Melbourne, VIC Australia

Ligy Philip Indian Institute of Technology Madras Chennai, Tamil Nadu India

Li Shu LJS Environment Parkville, VIC Australia

Ashok Natarajan Tamilnadu Water Investment Company Chennai, Tamil Nadu India

Gregory Griffin RMIT University Melbourne, VIC Australia

Sajid Hussain Tamilnadu Water Investment Company Chennai, Tamil Nadu India

Applied Environmental Science and Engineering for a Sustainable Future ISBN 978-3-319-75198-6 ISBN 978-3-319-75199-3 (eBook) https://doi.org/10.1007/978-3-319-75199-3 Library of Congress Control Number: 2018934443 © Springer International Publishing AG, part of Springer Nature 2019 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Printed on acid-free paper This Springer imprint is published by the registered company Springer International Publishing AG part of Springer Nature The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

Foreword

Water scarcity is a global issue. ‘By 2015, two-thirds of the world’s population may face water shortages. Ecosystems around the world will suffer even more’ says the World Wildlife Fund. Another dire prediction says that future wars will be fought over water. Conserving freshwater and recovering resources are key factors for a sustainable future. Almost all industries agriculture, aquaculture, manufacturing, etc. need water of varying qualities. Therefore, efficient water management is paramount importance for those industries in order (i) for sustainable usage of available freshwater; (ii) to reduce the discharge of pollutants to the receiving water bodies and (iii) to reuse resources such as water and other chemicals. This is compounded by the deterioration in the water quality due to partially treated (or untreated) industrial discharges as well as adverse conditions such as frequent droughts, storms and flooding caused by climate change. The findings in this book can be applied for any industry that use significant quantities of water in their processes such as food and beverage, tobacco, textile, leather, wood, paper and non-metal mineral industries. The contents of this book were from two workshops on ‘Water scarcity and ways to reduce the impact’ which were held at the Indian Institute of Technology, Madras in Chennai, India and the Royal Melbourne Institute of Technology (RMIT) University in Melbourne, Australia on 15 and 16 January and on 9 and 10 June 2016, respectively. These workshops were supported by the Australia–India Council grant were aimed to develop methods and propose techniques to alleviate the physical effects of water scarcity in 2025 and to advance research cooperation between RMIT University in Australia, Tamil Nadu Water Investment Company and the Indian Institute of Technology, Madras in India in the following areas: 1. Reverse osmosis process, 2. Forward osmosis, 3. Zero liquid discharge, 4. Resource recovery and 5. Disinfection by-products. I see that the book covers all the above aspects that aligned with the title of the book and has focused on how we could alleviate the effects of water scarcity and learn more about the technology that are suitable for future smart cities.

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Foreword

Water scarcity in many countries is primarily due to human factors including industrialisation, irrigation and domestic growth. I sincerely hope that the book educates and informs the readers from all countries on how we can get ready for the future. I had a privilege to attend and present at one of these workshops held in IIT Madras. I was impressed with the deliberations and range of presentations at that workshop. I convey my best wishes to the editorial team for their future endeavours. I hope that these workshops and the book contribute to future collaborations between Australia and India in the water sector. Both countries face somewhat similar challenges and there is immense scope to work together to overcome some of these challenges. Australia

Gopi Shankar Director—Trade & Industry State Government of Victoria

Preface

It is with great pleasure that we write this preface for this book titled ‘Water Scarcity and Ways to reduce the impact—Management Strategies and Technologies for Zero Liquid Discharge and Future Smart Cities’. We sincerely hope that the knowledge you gain from this book would help you to better understand various processes involved in water as utilities—food, pharmaceutical, textile, mining, agricultural and similar industries. Water is very critical for a sustainable life. Water access, distribution and quality are the most urgent challenges for societies across the world. The focus of the book is to bring academia, industry and research organisations to discuss water scarcity and find ways to reduce the impact. This book arises from the selected presentations held at RMIT University and at IIT Madras in 2016. The common theme that sets the objective of these workshops was ‘water scarcity and ways to reduce the impact’. The two workshops drew a wide range of expertise from various organisations such as industries, Universities and research institutes. The workshops were focused not only to discuss the technological options, various treatment methods to address water scarcity but to motivate and to create the awareness among the potential users and other stakeholders to encourage to adopt the technology in their current processes. Management and technology were considered to be important in implementing zero liquid discharge (ZLD) in industries that could assist greatly to conserve freshwater resources which in turn will help sustainability of water. Management of ZLD needs to find answers for questions such as the appropriateness and importance of ZLD and when and why ZLD does not work, policies on ZLD and how policymakers should work with industries, case studies on the success of ZLD and willingness for improvements and how integrated water management should be given priority. Similarly, the technology should consider the implementations of simple and advanced technologies such as membrane filtration and distillation, advanced oxidation processes with photocatalysis and brine management. The workshop held in Chennai, India identified the following factors as the immediate concerns with respect to management: standardisation, operation and maintenance, synergy between industry, policy makers and public, complete ecosystem and honesty. With respect to technology, appropriate technologies (better brine volume vii

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Preface

reduction; salt recovery), development of local manufacturing (membranes and other materials) and demand quality in everything were considered to be given priority. The second workshop at RMIT University emphasised the need to understand the issues related to water such as drought and flooding, cyclones, surface and groundwater contamination as well as brine management. This will then help to develop techniques and processes to combat those issues. Policy and management should bridge the gap between various stakeholders and also should assist to facilitate the introduction of new schemes that are essential in tackling issues related to water. Mathematical modelling is considered an important tool for integrated catchment management. Models on hydrology, water resource management, water distribution, sewer networks and process optimisation should be integrated appropriately. This book brings out some of the key aspects on water scarcity and ways to reduce the impact. We hope this will pave way for more research collaborations and contribute to outcomes which will lead to sustainable future for water. Melbourne, VIC, Australia Melbourne, VIC, Australia Parkville, VIC, Australia

Veeriah Jegatheesan Muthu Pannirselvam Li Shu

Acknowledgements

On behalf of our colleagues at RMIT University and our research partners of this joint project focused on water scarcity, the editors of the book would like to thank all speakers at the workshops that were the key drivers of this research output. We would like to thank Australia–India research council and their staff for their financial support. We would like to thank Ms. Forte and her colleagues at the Australia–India council for her support. We would like to thank Consul General Hon Sean Kelly, Mr. Skandan, TNPCB Chairman (former), Prof. Bhaskar Ramamurthi at IIT Madras and Dr. Grayson Perry, Trade commissioner for their exhilarating speeches at the opening ceremony held of the first workshop held at IIT Madras in February 2015. We would like to specially thank Mr. Gopi Shankar from the Victorian government office in Bengaluru India, Mr. Chris O’Neill from Hydronumerics and Dr. Chris Dallimore for their excellent support. We would like to thank all the college of Science, Engineering and Health office as well as Prof. Peter Coloe, Mr. Paul Brown and the whole team at the RMIT University College of SEH office. We would like to thank the following speakers that shared their vast knowledge at this workshop Prof. Vinod Tare from IIT Kanpur, Mr. Kumar from Tamilnadu Pollution Control Board, Mr. Manoharan from Industrial Waste Management, Prof. Srinivasan Madapusi from RMIT University, Mr. Gopi Shankar from Victorian state government office in India, Mr. Nischal Wadekar from Concord Enviro system, Dr. Jenny Gronwall from Water Governance Unit of the Stockholm International Water Institute, Prof. B. S. Murthy, Dr. Kannan and Dr. K. S. Reddy from IIT Madras, Mr. Ashok Natarajan from TWIC, Mr. Sajid Hussain from TWIC, Dr. Ludo Diels from VITO NC Belgium, Prof. Absar Kazmi from IIT Roorkee, Prof. Ligy Philip from IIT Madras, Prof. Kurien Joseph from Anna University, Prof. Sabu Thomas from Mahatma Gandhi University, Dr. Gregory Griffin from RMIT University and Dr. Shobha Muthukumaran from Victoria University. We would like to thank Prof. Suresh Bhargava, Prof. Peter Fairbrother and Prof. Sujeeva Setunge from RMIT University for their welcome introduction and welcome speech at the workshop held in June 2015 at RMIT University. We would like to thank the following speakers at this workshop held at RMIT for presenting their findings and

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Acknowledgements

research outcomes: Mr. Ashok Natarajan and Mr. Sajid Hussain from Tamilnadu Water Investment Company, Prof. Ligy Philip from IIT Madras, Mr. Peter Gee from Water Services Association of Australia, Dr. Ravi Raveendran from South Gippsland Water, Dr. Daniel Lester from RMIT University, Mr. Joe Cucuzza from AMIRA, Mr. Kit Andrews and Ms. Heather Mallinson from RMIT University, Prof. Mushtaque Ahmed from Sultan Qaboos University, Mr. Peter Merchant from ITS Pipetech, Prof. Mikel C. Duke from Victoria University, Prof. Chettiyappan Visvanathan from Asian Institute of Technology, Dr. Robert Carr from eWater, Prof. Vincent Pettigrove from the University of Melbourne, Mr. Chris O’Neil from Hydronumerics, Dr. Gregory Griffin and Prof. Srini Madapusi, Mr. Damien Thomas, Prof. Oliver Jones from RMIT University, Mr. Philip Adetunji from Qenos, Mr. Ranga Fernando from Yarra Valley Water, Dr. Matthew Currell, Dr. Jorge Paz-Ferreiro, Dr. Maazuza Othman from RMIT University, Dr. Shobha Muthukumaran and Dr. Dimuthu Navaratna from Victoria University, Dr. Ludovic Dumee and Prof. Bas Baskaran from Deakin University, Mr. Ganesh Sen from Reach4YFF, Dr. Linhua Fan and Prof. Aidyn Mouravod from RMIT University. We would like to thank Mr. S. Krishnakumar from Kenmore Air Travels Pvt Ltd., for their excellent support organising our itinerary during the trip to India and visiting various industries and manufacturing sites. We would like to thank all the research students and staff Dr. Thangavadivel Kandaswamy, Dr. Mohammad Al Kobaisi, Dr. Sushanthi Layanarchi, Dr. Harishankar and Dr. Biplob Kumar Pranaik for their support.

Contents

1

2

3

4

5

6

Sustainable Management of Municipal Wastewater Reverse Osmosis Concentrate: Treatment with Biological Activated Carbon Based Processes for Safe Disposal . . . . . . . . . . . . . . . . . . . Linhua Fan and Felicity A. Roddick

1

Sustainable Wastewater Management Through Decentralized Systems: Case Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ligy Philip, C. Ramprasad and D. Krithika

15

Nanofiltration of Dye Bath Towards Zero Liquid Discharge: A Technical and Economic Evaluation . . . . . . . . . . . . . . . . . . . . . . Li Shu, Muthu Pannirselvam and Veeriah Jegatheesan

47

Treating Car Wash Wastewater by Ceramic Ultrafiltration Membranes for Reuse Purposes . . . . . . . . . . . . . . . . . . . . . . . . . . . Jamie Wills, Shamima Moazzem and Veeriah Jegatheesan

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Microalgae as Bio-Converters of Wastewater into Biofuel and Food . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mohammad Raza Siddiqui, Ana Miranda and Aidyn Mouradov

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Effect of Hybrid Photocatalysis and Ceramic Membrane Filtration Process for Humic Acid Degradation . . . . . . . . . . . . . . . Lili Song, Bo Zhu, Veeriah Jegatheesan, Stephen R. Gray, Mikel C. Duke and Shobha Muthukumaran

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Potential Use of Biochar from Sugarcane Bagasse for Treatment of Textile Wastewater . . . . . . . . . . . . . . . . . . . . . . . 115 Sinem Ograk, Gregory J. Griffin and Muthu Pannirselvam

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Disinfection By-products in Recycled Waters . . . . . . . . . . . . . . . . . 135 Lydon D. Alexandrou, Barry J. Meehan and Oliver A. H. Jones

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Contents

Functional Nanoporous Titanium Dioxide for Separation Applications: Synthesis Routes and Properties to Performance Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Andrea Merenda, Lingxue Kong, Bo Zhu, Mikel C. Duke, Stephen R. Gray and Ludovic F. Dumée

10 Addressing Water Scarcity in Tamilnadu: New Perspective . . . . . . 187 Ashok Natarajan 11 Repair or Replace: Technologies Available for Trenchless Remediation of Existing Infrastructure . . . . . . . . . . . . . . . . . . . . . . 197 Peter Marchant Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219

Contributors

Lydon D. Alexandrou Australian Centre for Research on Separation Science, Water: Effective Technologies and Tools (WETT) Research Centre, School of Science, RMIT University, Melbourne, VIC, Australia Mikel C. Duke College of Engineering and Science, Victoria University, Melbourne, VIC, Australia; Institute for Sustainability and Innovation, Victoria University, Melbourne, VIC, Australia Ludovic F. Dumée Institute for Frontier Materials, Deakin University, Waurn Ponds, Geelong, VIC, Australia Linhua Fan Department of Chemical and Environmental Engineering, School of Engineering, RMIT University, Melbourne, Australia Stephen R. Gray College of Engineering and Science, Victoria University, Melbourne, VIC, Australia; Institute for Sustainability and Innovation, Victoria University, Melbourne, VIC, Australia Gregory J. Griffin School of Engineering, RMIT University, Melbourne, VIC, Australia Veeriah Jegatheesan School of Engineering, RMIT University, Melbourne, VIC, Australia Oliver A. H. Jones Australian Centre for Research on Separation Science, Water: Effective Technologies and Tools (WETT) Research Centre, School of Science, RMIT University, Melbourne, VIC, Australia Lingxue Kong Institute for Frontier Materials, Deakin University, Waurn Ponds, Geelong, VIC, Australia D. Krithika Department of Civil Engineering, Indian Institute of Technology Madras, Chennai, India Peter Marchant ITS Pipetech Pty Ltd, Seven Hills, Australia

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Contributors

Barry J. Meehan Water: Effective Technologies and Tools (WETT) Research Centre, School of Science, RMIT University, Melbourne, VIC, Australia Andrea Merenda Institute for Frontier Materials, Deakin University, Waurn Ponds, Geelong, VIC, Australia Ana Miranda School of Science, RMIT University, Melbourne, VIC, Australia Shamima Moazzem School of Engineering, Royal Melbourne Institute of Technology (RMIT) University, Melbourne, VIC, Australia Aidyn Mouradov School of Science, RMIT University, Melbourne, VIC, Australia Shobha Muthukumaran College of Engineering and Science, Victoria University, Melbourne, VIC, Australia; Institute for Sustainability and Innovation, Victoria University, Melbourne, VIC, Australia Ashok Natarajan Tamilnadu Water Investment Company, Chennai, Tamil Nadu, India Sinem Ograk School of Engineering, RMIT University, Melbourne, VIC, Australia Muthu Pannirselvam College of Science, Engineering and Health, RMIT University, Melbourne, VIC, Australia Ligy Philip Department of Civil Engineering, Indian Institute of Technology Madras, Chennai, India C. Ramprasad Department of Civil Engineering, Indian Institute of Technology Madras, Chennai, India Felicity A. Roddick Department of Chemical and Environmental Engineering, School of Engineering, RMIT University, Melbourne, Australia Li Shu School of Engineering, RMIT University, Melbourne, Australia Mohammad Raza Siddiqui Department of Agronomy, Balochistan Agriculture College, Quetta, Pakistan Lili Song College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou, People’s Republic of China Jamie Wills School of Engineering, Royal Melbourne Institute of Technology (RMIT) University, Melbourne, VIC, Australia Bo Zhu College of Engineering and Science, Institute for Sustainability and Innovation, Victoria University, Melbourne, VIC, Australia

Abbreviations

AAO ACWA ADWG ALD AOP AP I AP II ARMCANZ AS BAC BaP BOD BTEX CIPP CNHS COD CVD Da DAP DBAA DBP DCAA DGGE DOC DO DTG EBCT ECD EC

Anodic aluminium oxide Australian Car Wash Association Australian Drinking Water Guidelines Atomic Layer Deposition Advanced Oxidation Process Aromatic Protein I (from EEM spectra) Aromatic Protein II (from EEM spectra) Agriculture and Resource Management Council of Australia and New Zealand Ammonium Sulphate Biologically Activated Carbon Benzo[a]pyrene Biochemical Oxygen Demand Benzene, Toluene, Ethylbenzene and Xylenes Cast-in-place-pipe Carbon Nitrogen Hydrogen Sulphur Chemical Oxygen Demand Chemical Vapour Deposition Dalton Diammonium Phosphate Dibromoacetic Acid Disinfection By-Product Dichloroacetic acid Denaturing Gradient Gel Electrophoresis Dissolved Organic Carbon Dissolved oxygen Differential Thermal Gravimetry Empty Bed Contact Time Electron Capture Detection Emerging Contaminants

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EEM FA FC FRI FRP FTIR GAC GC H2O2 HAA HA HDPE HF HK HPLC HRT HYCW IC LMW MBAA MBR MCAA MED MF MLD MS MST MW NDMA NF NHMRC NOM NTU O3 PA-ALD PAH PAN PAOs PCR PE PET PG PHE PMR ppb

Abbreviations

Excitation-Emission Matrix Fulvic Acid Faecal Coliforms Fluorescence Regional Integration Fibre-Reinforced Plastic Fourier-Transform Infrared Spectroscopy Granular Activated Carbon Gas Chromatography Hydrogen Peroxide Haloacetic Acid Humic Acid High-Density Polyethylene Horizontal Flow Haloketones High-Performance Liquid Chromatography Hydraulic Retention Time Hybrid Constructed Wetland Ion Chromatography Low Molecular Weight Monobromoacetic acid Membrane Bioreactor Monochloroacetic Acid Multi-effect Distillation unit Microfiltration Million Litres per day Mass spectrometry Modified Septic Tank Molecular Weight N-Nitrosodimethylamine Nanofiltration National Health and Medical Research Council Natural Organic Matter Nephelometric Turbidity Unit Ozone Plasma-Assisted Atomic Layer Deposition Polyaromatic hydrocarbon Polyacrylonitrile Polyphosphate accumulating organisms Polymerase Chain Reaction Polyethylene Polyethylene Terephthalate Polyethylene Glycol Phenanthrene Photocatalytic Membrane Reactor Parts per billion

Abbreviations

ppm PPP ppt PTFE PU PVC PYRE ROC RO SCB SDS SMP SWRO TCAA TDS TGA THMFP THM TMA TMP TN TPH TP TSS TTHM TTIP TWAD UF ULB USEPA UVA254 UVT UV VF VOC WHO WWTP WW ZLD

xvii

Parts per million Public Private Partnership Parts per thousand Polytetrafluoroethylene Polyurethane Polyvinyl Chloride Pyrene Reverse Osmosis Concentrate Reverse Osmosis Sugar cane bagasse Sodium Dodecyl Sulphate Soluble Microbial Products Seawater reverse osmosis Trichloroacetic acid Total Dissolved Solids Thermogravimetric analysis Trihalomethane Formation Potential Trihalomethane Trimethyl Amine Transmembrane pressure Total Nitrogen Total Petroleum Hydrocarbon Total Phosphorus Total Suspended Solids Total Trihalomethane Titanium Tetraisopropoxide Tamilnadu Water Supply and Drainage Ultrafiltration Urban Local Bodies United States Environmental Protection Agency Absorbance measured at 254 nm Ultraviolet Transmittance Ultraviolet Vertical Flow Volatile Organic Compounds World Health Organisation Wastewater Treatment Plant Waste Water Zero Liquid Discharge

Chapter 1

Sustainable Management of Municipal Wastewater Reverse Osmosis Concentrate: Treatment with Biological Activated Carbon Based Processes for Safe Disposal Linhua Fan and Felicity A. Roddick

Abstract Reverse osmosis concentrate (ROC) streams generated from RO-based municipal wastewater reclamation processes pose environmental and health risks on their disposal to sensitive water environments. Management of the ROC remains a big economic and technological challenge for the water industry to sustain the practice of water recycling. This paper presents some recent investigations into the effectiveness of biological activated carbon (BAC) process, as a potentially cost-effective and environmentally benign treatment option, for removing organic matter and nutrients (N and P) from the ROC and reducing its toxicity. The impact of ROC characteristics and pretreatment options including advanced oxidation (UV/H2O2) and chemical coagulation (FeCl3) on the treatment efficiency is discussed. Further information about bacterial communities in the BAC system is provided for a better understanding of the effectiveness and robustness of the BAC system at different salinity levels. Overall, BAC-based processes have been demonstrated as a resilient treatment for reducing the environmental risks associated with municipal wastewater ROC.




Keywords Reverse osmosis concentrate Biological activated carbon process Recycled wastewater Sustainable management




1.1

Introduction

Recycled wastewater is actively being considered as a supplementary water supply to address water scarcity around the world. Over recent decades, municipal wastewater reclamation through the advanced treatment of biologically treated L. Fan (&)
F. A. Roddick Department of Chemical and Environmental Engineering, School of Engineering, RMIT University, Melbourne, Australia e-mail: [email protected] © Springer International Publishing AG, part of Springer Nature 2019 M. Pannirselvam et al. (eds.), Water Scarcity and Ways to Reduce the Impact, Applied Environmental Science and Engineering for a Sustainable Future, https://doi.org/10.1007/978-3-319-75199-3_1

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L. Fan and F. A. Roddick

secondary effluent using reverse osmosis (RO)-based processes has increased rapidly to produce high-quality recycled water that is suitable for a wide range of beneficial uses in agricultural, industrial and domestic sectors (Shannon et al. 2008). However, the RO-based reclamation processes inevitably produce a waste stream termed RO concentrate (ROC) (also known as membrane reject or RO brine) which contains almost all of the contaminants derived from the secondary effluent at elevated levels. The organic contaminants in municipal wastewater ROC commonly include recalcitrant chemicals such as pharmaceuticals, pesticides, endocrine disrupting compounds, disinfection by-products and other organic species, many of which are toxic and bio-accumulative (Westerhoff et al. 2009). Moreover, the elevated nutrient (N and P) levels of the ROC can have adverse implications to the receiving aquatic ecosystems, such as eutrophication (Chen et al. 2011). The characteristics of the ROC can vary significantly from stream to stream, depending on factors such as source of wastewater, catchment conditions, pretreatment, membrane process used and water recovery. Moreover, the chemicals used for membrane scaling inhibition, biofouling control and cleaning can further change the characteristics of organic and inorganic pollutants present in the ROC (Van Der Bruggen et al. 2003). Sustainable management of the ROC is widely regarded as a key technological and economic challenge for the water industry in the application of RO-based wastewater reclamation. In general, the management options for municipal wastewater ROC may include (1) ocean outfall/surface water discharge with/without dilution; (2) sewer discharge; (3) deep well injection; (4) land application and (5) evaporation ponds/zero liquid discharge. The selection of a suitable method is dependent upon regulations and management objectives. Ocean outfall/surface water discharge represents a relatively inexpensive option and hence appears to be a popular practice currently for many wastewater reclamation plants, particularly for those located in coastal areas. However, there is a growing concern from environmental authorities and general public about the long-term impact of this practice on the receiving aquatic ecosystems, particularly confined water bodies such as bays and estuaries. As such, it is necessary to explore cost-effective and environmentally friendly treatment options for the ROC to reduce its organic and nutrient content, and hence the environmental and public health risks on its disposal or reuse. Due to the recalcitrant nature of the organic matter in the ROC, several treatment options including coagulation, and oxidative treatment processes such as UV/H2O2, UV/TiO2, ozonation and Fenton processes have been investigated as single or combined treatments for removing organic matter from municipal wastewater ROC with various characteristics (Westerhoff et al. 2009; Bagastyo et al. 2011; Lu et al. 2013). UV/H2O2 is an attractive advanced oxidation process (AOP) as it produces hydroxyl radicals (HO˙) which can non-selectively oxidise the organic molecules to mineralise and/or break down the organic compounds into smaller molecules which are largely biodegradable (Parsons 2004). Some recent studies have suggested that the use of biological treatment such as biological activated carbon (BAC) following the oxidation would improve the cost-effectiveness of the ROC treatment

1 Sustainable Management of Municipal Wastewater Reverse …

3

(Westerhoff et al. 2009). The BAC process can provide simultaneous adsorption of non-biodegradable matter and oxidation of biodegradable matter by the microorganisms attached to the granular activated carbon particles in a single reactor (Walker and Weatherley 1999). However, there is generally a lack of knowledge regarding BAC-based ROC treatment, particularly on the impact of ROC salinity (TDS of municipal wastewater ROC may vary from 2 to 20 g/L, according to the published literature) and type of organic compounds which may greatly affect the biological treatment. Several recent studies conducted by the authors’ research group have demonstrated the potential of the BAC-based processes for organic matter and nutrient removal from municipal wastewater ROC streams (Pradhan et al. 2015, 2016; Pradhan 2016; Roddick et al. 2016). The following sections summarise the key findings from these studies, with a focus on the investigations of the impact of key ROC characteristics and pretreatment methods on the overall efficiency of the BAC-based treatment processes such as UV/H2O2-BAC and coagulation-BAC in terms of reduction in organic matter and nutrients, and change in disinfection by-product (DBP) content and ecotoxicity. The microbial communities which are responsible for the removal of organic matter and nutrients from two different types of ROC and the effect of BAC on ecotoxicity of the ROC are also presented.

1.2

Impact of ROC Characteristics on the UV/H2O2-BAC Treatment

Municipal wastewater ROC usually contains numerous substrates and its organic and inorganic compositions may vary greatly. The individual treatments including UV/H2O2 and BAC, and their combination on the two different types of ROC (denoted as ROC A and B) obtained from the reclamation facilities of two Australian wastewater treatment plants (WWTPs) were compared for a better understanding of the impact of the characteristics of the ROC on the treatment efficacy. ROC A was collected from a wastewater reclamation facility treating mostly domestic wastewater, and ROC B was collected from a reclamation facility receiving secondary effluent from a biological sewage treatment process which treats influent containing domestic wastewater and the trade waste primarily discharged by a petrochemical processor (30% v/v). The characteristics of the two ROC samples used for the study were very different in terms of salinity, organic matter and nutrients (Table 1.1). There was significantly higher fluorescence intensity for the spectral regions representing fulvic acid-like substances (FA-like, III) and humic acid-like substances (HA-like, V) compared with aromatic proteins (API and APII) and soluble microbial products (SMPs, IV) for both ROCs (Fig. 1.1a, b) (Chen et al. 2003). ROC B exhibited extra fluorescence peaks in region III at Ex/Em: 375–400 nm/220–260 nm and region V at Ex/Em: 375– 400 nm/260–285 nm and at Ex/Em: 375–400 nm/350–380 nm (Fig. 1.1b). These

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Table 1.1 Characteristics of ROC A and B Parameters

ROC A

ROC B

DOC (MG/L) Colour (PT-CO) UVA254 (/CM) COD (MG/L) TN (MG/L) NH4-N (MG/L) NO3-N (MG/L) TP (MG/L) Chloride (MG/L) DO (MG/L) PH Conductivity (MS/CM) TDS (G/L)

36 148 0.62 120 21.4 4.3 9.1 28.5 7700 10.2 7.7 23.5 16.6

52 167 1.12 141 28.0 2.2 22 52 2600 8.6 7.5 7.8 4.5

Fig. 1.1 Fluorescence excitation-emission matrix (EEM) spectra of a ROC A and b ROC B

extra peaks could be related to some petrochemical compounds such as hydrocarbons present in the ROC. The UV/H2O2 treatment tests were conducted in batch mode with ROC samples dosed with 3 mM H2O2 and then exposed to UV irradiation for 30 min (UV dose of 16 J/cm2). The BAC tests involved the use of GAC columns inoculated with microbes derived from the activated sludge from the biological treatment processes at the respective WWTPs. BAC runs were conducted at room temperature (22–28 °C) in downflow mode with the empty bed contact time (EBCT) of 60 min. More details about the treatment systems were reported by Pradhan et al. (2015, 2016). The UV/H2O2 treatment led to considerably higher reductions in DOC, COD and UVA254 for ROC B compared with ROC A (Fig. 1.2a), although the colour removal was comparable for the two ROC types. With the BAC alone treatment,

1 Sustainable Management of Municipal Wastewater Reverse …

(a) 100 80

ReducƟon (%)

Fig. 1.2 Removal efficiency (%) of a organic matter and b nutrients from ROC A and B by UV/H2O2, BAC and their combination

5

60

DOC COD

40

UVA254 Colour

20 0 ROC A

ROC B

ROC A

UV/H2O2

ROC B

BAC

ROC A

ROC B

UV/H2O2-BAC

(b) 100 ReducƟon (%)

80 TN

60

NH4+-N

40

NO3--N

20

TP

0 ROC A

ROC B

ROC A

ROC B

ROC A

ROC B

-20 UV/H2O2

BAC

UV/H2O2-BAC

comparable DOC removal was achieved for both ROC types, whereas COD removal (47%) was higher for ROC B compared with ROC A (32%). However, colour (80%) and UVA254 (64%) removals were greater for ROC A than ROC B (74 and 55% for colour and UVA254, respectively). The trend in DOC, UVA254 and colour reduction for ROC A and ROC B was similar after the UV/H2O2-BAC treatment, whereas the reduction in COD was higher for ROC B (59%) compared to ROC A (48%). The greater reduction in COD for ROC B could be due to the combined effects of lower salinity of the ROC and/or the presence of more readily biodegradable organics in it (Pradhan 2016). Dinçer and Kargi (2001) also reported a decrease in COD removal (from 96 to 43%) when the salinity of wastewater increased from 2 to 13 g/L. As the ROC B contained petrochemical compounds and some compounds would be volatile in nature, it was possible that these compounds could be more easily degraded and/or stripped from the ROC during the AOP treatment. This may have resulted in the higher organic matter removal from ROC B compared with the ROC A. The UV/H2O2-BAC treatment on both types of ROC gave comparable DOC, colour and UVA254 removals regardless of salinity levels, but COD removal was higher for ROC B. The combined process was highly effective for reducing colour and UV absorbance, and their reductions were attributed to the effective breakdown of the organic chromophores present in these ROC streams.

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The UV/H2O2 alone treatment led to minimal removal of nutrients from both ROC A and ROC B (Fig. 1.2b). It was observed there was around 1–2 mg/L increase in nitrate after the oxidation treatment of both ROCs which was attributed to the conversion of some nitrogen species into NO3 -N in the presence of oxidant. With the BAC alone treatment, comparable high ammonium removal was obtained for both ROCs, with 90–93% reduction achieved (Fig. 1b). However, higher TN removal was obtained for ROC A than ROC B (71% cf. 21%). Nitrate removal was markedly lower for ROC B with only 7% reduction and higher for ROC A with 61% reduction. TP removal was significantly higher for the ROC B compared with ROC A (i.e. 58% cf. 8%). With the combined treatment, markedly lower reductions in TN and NO3 -N were obtained for ROC B than ROC A (15% cf. 60% for TN, and 5% cf. 61% for NO3 -N). It was shown that denitrification was much less for ROC B than for ROC A as indicated by less nitrate removal, affecting the overall nitrogen removal. However, there were comparable high ammonium removals for both ROCs with approximately 90% reduction achieved. For both ROCs, there was less denitrification than nitrification, which was likely due to the dissolved oxygen (DO) level of the ROC (typically 6–7 mg/L) being higher than required for denitrification (i.e. DO should be less than 1.5 mg/L). The denitrification was thought to have occurred within the microenvironment deep inside the BAC pores where there is limited oxygen penetration (Jin et al. 2013). In contrast to the nitrogen species, a significantly higher TP removal was achieved with BAC alone (58%) and the combined treatment for ROC B (64%) compared with the combined treatment for ROC A (15%). The contrary trends for nutrient removals for the two types of ROC could be related to difference in factors such as salinity level, organic constituents, different bacterial communities present in the BAC systems and the C:N ratio. The low phosphorus removal for ROC A was consistent with the finding that phosphorus-accumulating bacteria were greatly inhibited by increasing salinity at >5 g/L (Uygur and Kargı 2004). At higher salinity, plasmolysis of polyphosphate-accumulating organisms (PAOs) can take place, causing lower phosphorus removal.

1.3

Bacterial Communities in BAC Media Exposed to the Two Different ROC Streams

PCR-DGGE-sequencing analysis of BAC media exposed to ROC A and B showed the presence of diverse microbial communities from different bacterial groups with different functions (Table 1.2). It was shown Pseudomonas sp. belonging to the c-Proteobacteria were common in the BAC systems treating ROC A and B. Pseudomonas bacteria are ubiquitous in soil and wastewater treatment plants and can play vital roles in nutrient recycling, of a wide range of organic chemicals such as phenol, petroleum hydrocarbons, aromatic hydrocarbons and polycyclic aromatic

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Table 1.2 Bacterial communities in the BAC media exposed to ROC A and B Nearest taxon

Similarity (%)

Phylum

Exposed to ROC

Pseudomonas sp. Pseudomonas stutzeri Bacillus thuringiensis Rhodococcus sp. Micrococcus sp. Ralstonia sp. Agrobacterium sp. Pseudomonas sp. Sphingopyxis sp.

100 99 99 99 99 99 97 99 99

C-Proteobacteria C-Proteobacteria Firmicutes Actinobacteria Actinobacteria B-Proteobacteria A-Proteobacteria C-Proteobacteria A-Proteobacteria

A

B

hydrocarbons, and polychlorinated biphenyls in soil and water environments (Sarró et al. 2005). However, their functions varied for nutrient removal from the two types of ROC. Rhodococcus sp. and Micrococcus sp. belonging to the actinobacteria were present in the BAC media exposed to ROC A and ROC B, respectively. Rhodococcus sp. can perform heterotrophic nitrification and aerobic denitrification in wastewater treatment plants (Chen et al. 2012). Micrococcus and Pseudomonas can accumulate a large amount of phosphorus under aerobic conditions and have a good phosphorus eliminating capacity for municipal wastewater (Nakamura et al. 1991; Li et al. 2003). Apart from the phosphorus-removing capacity of Micrococcus, it is a potential degrader of polynuclear aromatic hydrocarbons (PAHs) which are recalcitrant hydrophobic compounds generated from most petroleum refineries (Stringfellow and Alvarez-Cohen 1999). Since ROC B was derived from wastewater treating the trade waste derived mostly from a petrochemical process along with domestic wastewater, the presence of Micrococcus and Pseudomonas can be anticipated (Wei et al. 2015). The other bacterial communities present in the BAC media treating ROC B contained Ralstonia belonging to the b-Proteobacteria, Agrobacterium and Sphingopyxis belonging to the a-Proteobacteria. These bacterial communities were more similar to PAOs that can take up phosphorus as poly P, thereby reducing phosphorus concentration (Lee and Choi 1999; Seviour et al. 2003). It was observed that even though the bacterial communities belong to same groups, their functions varied in terms of nutrient removal. Furthermore, bacterial communities present in the activated sludge that had been used to inoculate the respective BAC media have also been investigated. Bacillus sp. belonging to the Firmicutes were detected in the activated sludge that was used to inoculate the BAC media treating ROC A and Chryseobacterium belonging to the Flavobacteriia were detected in the sludge used to inoculate the BAC media treating ROC B. Chryseobacterium sp. can enhance phosphorus removal from wastewater (Kämpfer et al. 2003), and Bacillus sp. are responsible for nitrification– denitrification and organic matter removal under adverse conditions such as higher salinity (Choi et al. 2002). The presence of different bacterial communities in the

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activated sludge and BAC media showed that microbes can adapt to varied treatment conditions. These different bacterial species have different affinities for organic matter and nutrient consumption, and do so at different rates, thereby affecting organic matter and nutrient removal at different salinities.

1.4

Impact of ROC Salinity on UV/H2O2-BAC Treatment

The impact of salinity of a municipal wastewater ROC on the efficiency of a bench-scale UV/H2O2-BAC batch treatment system was characterised by Pradhan et al. (2016) in terms of removal of organic matter and nitrogen species from three ROCs of different salinities (TDS of 7, 10 and 16 g/L) but the same organic and nutrient compositions. It was observed that the organic matter removal was comparable for the ROC over the tested salinity range, with 45–49% of DOC (initial concentration 43 mg/L) and 70–74% of UVA254 (initial value 0.6/cm) removed by the combined treatment (Fig. 1.3a). However, removal of TN was considerably

Fig. 1.3 Removal of a organic matter and b nitrogen species by the UV/H2O2-BAC treatment for the ROC of various salinities (number of analyses, n = 12 for each salinity level)

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higher for the ROC at the high salinity (TDS 16 mg/L) compared with the low (*7 g/L) and medium salinity (10 g/L) (Fig. 1.3b). Effective nitrification with high ammonium removal (>90%, initial value 4 mg/L) was achieved at all salinity levels, whereas greater denitrification (39%) was obtained at high salinity than low (23%) and medium salinity (27%). It appeared that the salinity of the ROC did not affect the ammonium removal, which is consistent with the ammonia oxidising bacteria being able to adapt to and grow over the salinity range of 0–35% (Glass and Silverstein 1999). In this study, the extent of denitrification was lower than nitrification which could be because of the high DO in the influent (*10 mg/L) as DO of the effluent from the BAC process at different salinities was 6–7 mg/L, and complete denitrification would normally take place when DO 90%) as a result of effective precipitation of phosphates during the coagulation (Fig. 1.4b). ROC A exhibited better TN removal

(a) 100 ReducƟon (100%)

80 DOC

60

COD 40

UVA254 Colour

20 0 ROC A

ROC B

CoagulaƟon-BAC

ROC A

ROC B

ROC A

CoagulaƟon-UV/H2O2-BAC

ROC B

BAC

(b) 100 80

ReducƟon (100%)

Fig. 1.4 Removal efficiency of a organic matter and b nutrients in the treatment of ROC A and B by BAC with and without pretreatment

TN

60

NH4+-N

40

NO3--N TP

20 0 ROC A

ROC B

ROC A

ROC B

ROC A

-20 CoagulaƟon-BAC CoagulaƟon-UV/H2O2-BAC

ROC B

BAC

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than ROC B after the various treatments, suggesting that salinity as well different organic constituents played important roles in nutrient removal. This study showed that better nitrogen removal was obtained at higher salinity, but higher phosphorus removal was achieved only at lower salinity (5 g/L) plasmolysis of polyphosphate-accumulating organisms (PAOs) can take place causing lower phosphorus removal. It was shown that microbes in the BAC system could adapt to varied treatment conditions, meaning that the BAC treatment is robust and resilient to possible changes in the physicochemical properties of the influent. The different bacterial species have different affinities for organic matter and nutrient, and consume them at different rates, thereby affecting organic matter and nutrient removal at different salinities. Coagulation-BAC appeared to be a more cost-effective treatment option compared with UV/H2O2-BAC as it would be less energy intensive and could achieve excellent total phosphorus removal. The ROC treated by the BAC-based processes showed DBP levels well below the current requirements in the Australian Drinking Water Guidelines and USEPA guidelines, and the BAC treatment generally exhibited an ecotoxicity-reducing effect for the ROC streams studied. Although the studies demonstrated that the BAC-based processes had the potential for treating municipal wastewater ROC streams to reduce their environmental and health risks on disposal or reuse, selection of the process and processing conditions should be made based on the characteristics of each specific ROC. More work should be done in order to justify the technological viability of the BAC-based processes and to gain a better understanding of the processes with a view to maximising treatment efficiency. It is also recommended that assessment of the technological and economic feasibility of other potentially viable pretreatment options be undertaken. The most promising treatment process(es) should be further developed and trialled at larger scale such as pilot plants to gain more operational data for potential full-scale applications. Acknowledgments The authors would like to thank Dr Shovana Pradhan for her significant contribution to the experimental work reported here.

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References ADWG. (2011). Australian drinking water guidelines 6. Australia: National Health and Medical Research Council. Bagastyo, A. Y., Keller, J., Poussade, Y., & Batstone, D. J. (2011). Characterisation and removal of recalcitrants in reverse osmosis concentrates from water reclamation plants. Water Research, 45, 2415–2427. Chen, B., Kim, Y., & Westerhoff, P. (2011). Occurrence and treatment of wastewater-derived organic nitrogen. Water Research, 45, 4641–4650. Chen, P., Li, J., Li, Q. X., Wang, Y., Li, S., Ren, T., et al. (2012). Simultaneous heterotrophic nitrification and aerobic denitrification by bacterium Rhodococcus sp. CPZ24. Bioresource Technology, 116, 266–270. Chen, W., Westerhoff, P., Leenheer, J. A., & Booksh, K. (2003). Fluorescence excitation— Emission matrix regional integration to quantify spectra for dissolved organic matter. Environmental Science and Technology, 37, 5701–5710. Choi, Y., Hong, S., Kim, S., & Chung, I. (2002). Development of a biological process for livestock wastewater treatment using a technique for predominant outgrowth of Bacillus species. Water Science and Technology, 45, 71–78. Clark, T., Stephenson, T., & Pearce, P. (1997). Phosphorus removal by chemical precipitation in a biological aerated filter. Water Research, 31, 2557–2563. Comstock, S. E., Boyer, T. H., & Graf, K. C. (2011). Treatment of nanofiltration and reverse osmosis concentrates: comparison of precipitative softening, coagulation, and anion exchange. Water Research, 45, 4855–4865. D’Elia, M., & Isolati, A. (1992). Observed synergistic effects of aluminium and iron salts in nutrients removal. Chemical Water and Wastewater Treatment II. Springer. Dinçer, A. R., & Kargi, F. (2001). Performance of rotating biological disc system treating saline wastewater. Process Biochemistry, 36, 901–906. Duan, J., Graham, N. J. D., & Wilson, F. (2003). Coagulation of humic acid by ferric chloride in saline (marine) water conditions. Water Science and Technology, 47(1), 41–48. Edzwald, J. K., & Haarhoff, J. (2011). Seawater pretreatment for reverse osmosis: Chemistry, contaminants, and coagulation. Water Research, 45, 5428–5440. Glass, C., & Silverstein, J. (1999). Denitrification of high-nitrate, high-salinity wastewater. Water Research, 33, 223–229. Jin, P., Jin, X., Wang, X., Feng, Y., & Wang, X. C. (2013). Biological activated carbon treatment process for advanced water and wastewater Treatment. London: InTech. Kämpfer, P., Dreyer, U., Neef, A., Dott, W., & Busse, H.-J. (2003). Chryseobacterium defluvii sp. nov., isolated from wastewater. International Journal of Systematic and Evolutionary Microbiology, 53, 93–97. Lee, S. Y., & Choi, J.-I. (1999). Production and degradation of polyhydroxyalkanoates in waste environment. Waste Management, 19, 133–139. Li, J., Xing, X.-H., & Wang, B.-Z. (2003). Characteristics of phosphorus removal from wastewater by biofilm sequencing batch reactor (SBR). Biochemical Engineering Journal, 16, 279–285. Lu, J., Fan, L., & Roddick, F. A. (2013). Potential of BAC combined with UVC/H2O2 for reducing organic matter from highly saline reverse osmosis concentrate produced from municipal wastewater reclamation. Chemosphere, 93, 683–688. Nakamura, K., Masuda, K., & Mikami, E. (1991). Isolation of a new type of polyphosphate accumulating bacterium and its phosphate removal characteristics. Journal of Fermentation and Bioengineering, 71, 258–263. Parsons, S. (2004). Advanced oxidation processes for water and wastewater treatment. London: IWA publishing. Pradhan, S. (2016). Treatment of municipal wastewater reverse osmosis concentrate using biological activated carbon based processes. Ph.D. Dissertation, RMIT University, Melbourne.

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Pradhan, S., Fan, L., & Roddick, F. (2015). Removing organic and nitrogen content from a highly saline municipal wastewater reverse osmosis concentrate by UV/H2O2-BAC treatment. Chemosphere, 136, 198–203. Pradhan, S., Fan, L., & Roddick, F. (2016). Impact of salinity on organic matter and nitrogen removal from a municipal wastewater RO concentrate using biologically activated carbon coupled with UV/H2O2. Water Research, 94, 103–110. Roddick, F. A., Fan, L., & Nguyen, T. (2016). Destruction of toxicity & reduction of organic content of municipal wastewater reverse osmosis concentrate, Smart Water Fund Project (80S– 8010), Final Report, http://www.waterra.com.au/project-details/140. Sarró, M. I., García, A. M., & Moreno, D. A. (2005). Biofilm formation in spent nuclear fuel pools and bioremediation of radioactive water. International Microbiology, 8, 223–230. Seviour, R. J., Mino, T., & Onuki, M. (2003). The microbiology of biological phosphorus removal in activated sludge systems. FEMS Microbiology Reviews, 27, 99–127. Shannon, M. A., Bohn, P. W., Elimelech, M., Georgiadis, J. G., Mariñas, B. J., & Mayes, A. M. (2008). Science and technology for water purification in the coming decades. Nature, 452 (7185), 301–310. Stringfellow, W. T., & Alvarez-Cohen, L. (1999). Evaluating the relationship between the sorption of PAHs to bacterial biomass and biodegradation. Water Research, 33, 2535–2544. Tatsi, A., Zouboulis, A., Matis, K., & Samaras, P. (2003). Coagulation–flocculation pretreatment of sanitary landfill leachates. Chemosphere, 53, 737–744. Umar, M., Roddick, F., & Fan, L. (2016). Comparison of coagulation efficiency of aluminium and ferric-based coagulants as pre-treatment for UVC/H2O2 treatment of wastewater RO concentrate. Chemical Engineering Journal, 284, 841–849. USEPA Guideline. (1998). Stage 1—Disinfectants and disinfection by-products: Final rule. EPA 816-F-01-010, Office of Water, US Environmental Protection Agency, USA [Federal Register, 60 (241), 69389]. Uygur, A., & Kargi, F. (2004). Salt inhibition on biological nutrient removal from saline wastewater in a sequencing batch reactor. Enzyme and Microbial Technology, 34, 313–318. Van Der Bruggen, B., Lejon, L., & Vandecasteele, C. (2003). Reuse, treatment, and discharge of the concentrate of pressure-driven membrane processes. Environmental Science and Technology, 37, 3733–3738. Walker, G. M., & Weatherley, L. R. (1999). Biological activated carbon treatment of industrial wastewater in stirred tank reactors. Chemical Engineering Journal, 75, 201–206. Wei, C., He, W., Wei, L., Li, C., & MA, J. (2015). The analysis of a microbial community in the UV/O3-Anaerobic/aerobic integrated process for petrochemical nanofiltration concentrate (NFC) treatment by 454-Pyrosequencing. PLoS One, 10, e0139991. Westerhoff, P., Moon, H., Minakata, D., & Crittenden, J. (2009). Oxidation of organics in retentates from reverse osmosis wastewater reuse facilities. Water Research, 43, 3992–3998. Yoshie, S., Makino, H., Hirosawa, H., Shirotani, K., Tsuneda, S., & Hirata, A. (2006). Molecular analysis of halophilic bacterial community for high-rate denitrification of saline industrial wastewater. Applied Microbiology and Biotechnology, 72, 182–189.

Chapter 2

Sustainable Wastewater Management Through Decentralized Systems: Case Studies Ligy Philip, C. Ramprasad and D. Krithika

Abstract There is a significant increase in the urban population in developing countries like India and consequently, this has thrown up a major challenge to Urban Local Bodies (ULBs) entrusted with the task of waste management. In India, less than 20% of the wastewater generated is getting treated. Recent studies indicate that the supply is roughly equal to the demand for the country, hiding wide regional variations with acute shortages in many parts. Since economic growth implies increased water use, the water situation can be expected to worsen rapidly. Even though water resources are not scarce from the perspective of total available water volumes, the precipitation is highly variable in time and space. In addition, the untreated or partially treated wastewater from human settlements is polluting the existing freshwater bodies, creating shortage of freshwater for different uses. Moreover, many studies have shown that centralized treatment plants are not a sustainable solution for countries like India, where the power supply is rarely continuous, and operation and maintenance are not secured. Hence, it will be advisable to treat the wastewater near to the point of generation and reuse it so that the environment is protected and reliable source of water supply is provided. Innovative decentralized wastewater treatment plants aiming not only at treating the wastewater but also providing other benefits such as the reuse of water, energy reuse or nutrient reuse—depending on the local context—are the need of the daywater treatment systems. Any sustainable wastewater management system should be oriented toward the 3R concept, i.e., reduce, recycle, and reuse. However, the selection of technologies/management strategies will be depending on the economic status of the society. An integrated wastewater management system is the base for a sustainable development in urban and peri-urban areas. It is important to quantify and characterize the amount of wastewater for (i) developing effective strategies to treat the wastewater, (ii) applying different technologies, i.e., anaerobic, followed by aerobic and physicochemical, and (iii) using the treated wastewater

L. Philip (&)
C. Ramprasad
D. Krithika Department of Civil Engineering, Indian Institute of Technology Madras, Chennai, India e-mail: [email protected] © Springer International Publishing AG, part of Springer Nature 2019 M. Pannirselvam et al. (eds.), Water Scarcity and Ways to Reduce the Impact, Applied Environmental Science and Engineering for a Sustainable Future, https://doi.org/10.1007/978-3-319-75199-3_2

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in a sustainable way taking into account the risks involved, e.g., using treated wastewater for toilet flushing, and landscaping. This chapter deals with the case studies of various sustainable decentralized/on-site wastewater treatment systems. Keywords Decentralized systems wastewater treatment systems

2.1


Wastewater management
Sustainable

Introduction

Water is one of the world’s most valuable resources, which are under constant threat due to climate change and resulting drought, explosive population growth, and waste. Consequent to rapid growth in population and increasing water demand, stress on water resources in India is increasing and per capita water availability is reducing day by day (Anderson et al. 2001). An increase in urban water supply results in an increased wastewater generation, as the depleted fraction of domestic and residential water use, is only in the order of 15–25% (Scott et al. 2004). Current and future freshwater demand can be met by enhancing water use efficiency and demand management. Domestic water consumption makes up 8% of total global water use (UNWATER 2012). In developed countries, domestic water use is often many times larger than the WHO minimum recommended per capita consumption and it contributes to about 75% of wastewater generated (Zhao et al. 2005). Domestic water comprises of water used for drinking, washing, cooking (potable); for transporting wastes (non-potable); and for other uses such as watering gardens and washing cars (non-potable), graywater and black water. Graywater includes the wastewater originating from bathrooms (30%), washing machines (10%), showers, and sinks (15%) (Morel and Diener 2006). Blackwater includes urine and feces (40%). It also includes human waste (containing pathogens), paper, soap, detergent residues, and food scraps. The amount of usage for each purpose mainly depends upon the habits, socioeconomic factors, cultural activities, and climatic conditions. Domestic water utilization is about 150–200 L of water for each person in a household per day. There is a large potential to reduce the household water consumption. One of the ways to reduce the impact of water scarcity and pollution is to expand water and wastewater reuse at source of generation (Eriksson et al. 2002; Friedler and Galil 2003). On-site wastewater treatment and recycling systems are sustainable as they treat wastewater from a home to a standard, where it can be used within the same community. General approach is to minimize freshwater utilization and pollutants crossing the boundary, and maximizing water reuse. Traditional wastewater treatment systems must be transformed from disposal-based linear systems to a recovery-based cyclic closed-loop system that promote the conservation of water and nutrient resource and contribute to public health. Integrated closed-loop systems are designed to recycle, filter, and reuse the water in the same environment.

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Using organic waste nutrient cycles, from “point-of-generation” to “point-ofproduction,” closes the resource loop and provides a better approach for the management of valuable wastewater resources. Failing to recover organic wastewater from urban areas means a huge loss of life-supporting resources (Cavallini and Young 2002). Decentralized close-loop systems are more flexible and can adapt easily to the local conditions of the urban area as well as grow with the community as its population increases (Jhansi and Mishra 2013). Additionally, individual or clusters of housing and isolated communities, where there is no connection to the public water supply and sewerage, may be benefitted with more readily available sources of water for potable uses (Kahinda et al. 2007; Cook et al. 2009). The recycling will be appropriate in a given situation depending on the availability of additional water resources, socioeconomic considerations, potential uses for the recycled water, the strategy of waste discharge, and public policies that may override economic and public health considerations or psychological acceptance (Mantovani et al. 2001). Water from recycling systems should fulfil four criteria: hygienic safety, esthetics, environmental tolerance, and technical and economical feasibility (Nolde and Dott 1991). When considering systems for individual households, aspects like required area, construction costs, operation and maintenance, socioeconomic and cultural aspects are becoming matters of concern. Socioeconomic considerations include community perceptions, risk involved and the costs of reuse systems. Despite a long history of wastewater reuse in many parts of the world, the question of safety of wastewater reuse still remains a puzzle mainly because of the quality of reuse water. Po et al. (2003) found that there is a lack of social research in understanding the public perception of reuse of water and psychological factors governing their decision making processes in reusing the treated water within same system. In general, public health concern is the major issue in any type of reuse of wastewater. It is difficult to delineate acceptable health risks and is a matter that is still seriously debated. Graywater, in particular, which is less polluted than municipal wastewater and comprises about 50–75% of domestic water consumption, can be treated to quality and reused within same system (in situ) for flushing the toilet (Santala et al. 1998), watering the garden or for cleaning purposes (Eriksson et al. 2002). For instance, car washing activity, with conventional car wash facilities, consumes about 150– 300 L. However, if we can treat the car wash wastewater using suitable treatment and reuse the same for car washing, it may consume only 10–50 L of drinking water, as per the survey conducted by Bharati et al. (2014). Similarly, wastewater from washing machine can be recycled back to washing machine. The rinse water from one load of laundry can be saved in a tank and subsequently, that water can be used to wash the next load, cutting the amount of water one uses for laundry by 50– 80%. However, in many places, graywater is being discharged directly into surface waters or used as irrigation water without any treatment (Dallas and Ho 2005). This leads to water shortages and to a significant deterioration of local soil and water quality (Gross et al. 2007; Maimon et al. 2010; Travis et al. 2010). Thus, wastewater from household is emerging as potential source for demand management after proper treatment. In a typical community, approximately 75–85% of the

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freshwater used by single house ends up in the municipal effluent; the rest is lost to evaporation, sprinkling on lawns, landscaping projects, etc. Loss of water by evaporation is irreversible. Therefore, if one can design a proper in situ recycling treatment system for each usage, it can save up to 80% of freshwater consumption. Wastewater from a household usually contains large quantities of biodegradable organic matter, nutrients, surfactants, oils and grease along with emerging contaminants, pathogens, and heavy metals (Baskar et al. 2009). Therefore, communities must take great care when reusing wastewater, since both chemical substances (more than 10,000 micropollutants) and biological pathogens threaten public health. Most of the conventional treatment systems are effective in removing organic matter and nutrients to a large extent but are incapable of removing many of the emerging contaminants (Petrovic et al. 2003). As a result, these compounds persist in the discharged environment for longer time. Several studies reported that the treated effluent shows the presence of emerging compounds (Verenitch et al. 2006). Proper treatment system should be provided to remove these emerging contaminants and pathogens from household wastewater and treat the water to various reuse standards. The in situ household wastewater treatment system generally comprises of confined units such as anaerobic septic tank(s) for primary treatments (storage, sedimentation, and anaerobic degradation of organic matter) and aerobic treatment units such as bioreactors, biofilters, and constructed wetlands (Conn et al. 2006), and a variety of new wastewater treatment technologies, such as membrane filtration systems and advanced oxidation. These have led to new ways of managing urban water systems and water resources (Daigger 2009). Conventional and highly engineered wastewater management technologies and strategies often focus on electromechanical solutions that are capital intensive and requires high capital investments for effective functioning. Additionally, these systems have shorter life cycles compared to many alternative and nature-based technologies, which offer opportunities for resource recovery also. Many examples of potable reuse treatment trains are reported throughout the world and recent discussions among water reuse experts have addressed the reliance on the existing systems to produce acceptable and safe water to consume (Rodriguez et al. 2009; Tchobanoglous et al. 2011; Pisani and Menge 2013; Gerrity et al. 2013). Even though a number of new approaches are available for recycling household wastewater in a closed-loop manner, they are not commercially used due to lack of treatment knowledge, cost of treatment and socioeconomic and cultural issues. A schematic of a possible close-loop system for an individual household is shown in Fig. 2.1. Innovative decentralized/on-site wastewater treatment plants aiming not only at treating the wastewater but also providing other benefits such as the reuse of water, energy reuse or nutrient reuse—depending on the local context—are the need of the day. Thus, wastewater reuse and recycling may be highly sustainable because reclaimed water, in addition to increasing its availability, can be fit-for-use and therefore avoid costly over-treatments. This means that it fulfils the requirements of the end users. In the case of India, taking into account that there is a low ratio of wastewater treatment, it can be beneficial in two ways: on one hand, it can lead to

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Fig. 2.1 Possible close-loop water and wastewater management system for an individual household

higher wastewater treatment ratios, and on the other, it can mitigate water scarcity scenarios. However, sociocultural, economical, and regional aspects have to be taken into account while selecting the technologies, to make the process sustainable.

2.2 2.2.1

Case Studies Constructed Wetlands as a Sustainable Option for Decentralized Wastewater Treatment

Constructed wetlands are artificially created ecosystems with a shallow basin ( 98%) for up to 12 h. The samples were dried and air sealed prior to TGA experiments.

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The mass loss kinetics of raw and treated bagasse was recorded by TGA experiments conducted using a Perkin Elmer STA 6000. The experiments were performed over a temperature range of ambient up to 800 °C under laboratory-grade nitrogen (flow rate = 20 mL/min) using a constant heating rate of 10 K/min. For all the experiments, the operating gas was switched to air to oxidise any organic char. The gases from the degrading samples of bagasse were transported via a heated (250 °C) transfer line to a FTIR—Perkin Elmer Spectrum 100, in which the gases were scanned continuously (each scan lasted 35 s) between 600 and 4000 cm−1 at 4 cm−1 resolution.

7.3 7.3.1

Results and Discussion Effect of Chemical Additives on Mass Loss Rates for SCB Pyrolysis

Figures 7.1 and 7.2 display differential thermal gravimetry (DTG) plots for untreated bagasse and impregnated bagasse (AS and DAP, respectively) heated at 10 K/min under a nitrogen atmosphere. The graph for the raw bagasse demonstrates that the degradation of bagasse initiates at below 200 °C and displays two

Fig. 7.1 DTG plots of bagasse and ammonium sulphate-treated bagasse

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Fig. 7.2 DTG plots of bagasse and DAP-treated bagasse

prominent peaks at 302 and 354 °C. The lower temperature peak denotes the peak rate of degradation of hemicellulose and the greater temperature peak relates to the peak rate of degradation of the cellulose component. The flat broader mass loss at higher temperatures relates to the degradation of the lignin content of the bagasse, which is widely acknowledged to degrade over a wide temperature range (Hu et al. 2007). These outcomes are compatible with data reported in the literature (Manya and Arauzo 2008). The DTG data for bagasse impregnated with AS (Fig. 7.1) shows that decomposition of the bagasse is shifted to lower temperatures and the rate of mass loss increased more rapidly as the amount of AS addition is increased. The degradation of cellulose from bagasse takes place through a competitive pathway of depolymerisation and dehydration reactions. The depolymerisation reactions produce levoglucosan, which further decomposes to various volatile gases, whereas the dehydration reactions produce char, water and carbon oxides (Statheropoulos and Kyriakou 2000). The thermal decomposition of ammonium sulphate to sulphuric acid and ammonia happens at temperatures between around 280 and 380 °C, therefore in the presence of sulphuric acid the cellulose decomposition was initiated at much lesser temperatures compared to the decomposition of unprocessed bagasse with the peak degradation rates occurring at around 321 °C for 0.01 M AS and around 240 °C for 0.05 and 0.1 M AS. The presence of AS shifts the degradation reactions by favouring the dehydration reactions with sulphuric acid acting as a catalyst to produce water and carbon with less volatile gases (Statheropoulos and Kyriakou 2000). This phenomenon also results in lower rate of mass loss and increased char yield at these lower concentrations. It is also understood that ammonia assists the degradation of cellulose as well as other components by reacting with transitional carbonyl species (Sekiguchi and Shafizadeh 1984; Fig. 7.1). For higher additive concentrations of 0.5 and 1 M of AS, the mass degradation peak is moved to lesser temperatures and intensity of mass loss deteriorates at even

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greater proportions as more bagasse is transformed into char rather than other products. At these higher concentrations, there are no two distinct peaks that were observed for lower concentrations of AS, whereas more varied minor peaks occur over the temperature range 200–350 °C, where the decomposition of AS is also dominant. The higher concentrations of the additive AS produce more sulphuric acid and ammonia which in return catalyses the degradation reactions of hemicellulose and cellulose more rapidly as well as evolve gases related to sulphate species (SO3, etc.) in this region. It seems that at the higher AS concentrations, the degradation of AS overlaps all the other peaks in that region where cellulose and hemicellulose degradations occur. This was also reported by Pappa et al. (1995), where they also studied the differential scanning calorimetry curves of pure AS and the decomposition of Pinus halepensis pine needles treated with higher concentrations of AS. As seen from the reaction mechanism below, the decomposition of AS is a simple mechanism and decomposition occurs when cellulose degradation takes place. AS decomposes in two steps: ammonia (NH3) is produced via two different reaction steps and sulphuric acid decomposes at around 380 °C to produce water and sulphate species (SO, SO2 and SO3) (Statheropoulos and Kyriakou 2000; Fig. 7.2). ðNH4 Þ2 SO4 ! NH3 þ NH4 HSO4 at around 280  C NH4 HSO4 ! NH3 þ H2 SO4 at around 280  C H2 SO4 ! SO3 þ H2 O at around 380  C The presence of DAP affects the degradation of bagasse similarly to AS (refer Fig. 7.2). For additive concentrations of 0.1, 0.5 and 1 M DAP, the rate of mass loss peaks are moved to lower temperatures of 274, 267 and 266 °C, respectively and the peak concentration drops significantly as the concentration of DAP gets higher, as more of the bagasse is converted to char. The rate of mass loss is less due to the fact that the formed char contains both the phosphorus and the nitrogen content of DAP, whereas the char yield is only enriched with nitrogen and sulphur for AS. The below equations show the decomposition of DAP at temperatures between 150 and 170 °C (Liodakis et al. 2003). ðNH4 Þ2 HPO4 ! NH3 þ NH4 HPO4 at 155  C ðNH4 Þ2 HPO4 ! NH3 þ H3 PO4 2H3 PO4 ! H2 O þ H4 P2 O7 at 170  C H4 P2 O7 ! 2H2 O þ P2 O5 The effect of DAP on the decomposition of bagasse between 180 and 450 °C has been credited to degradation of DAP to ammonia (NH3), phosphoric acid (H3PO4) as well as phosphorous pentoxide (P2O5). The phosphoric acid and phosphorus pentoxide catalyse earlier dehydration of hydroxyl groups while ammonia supports

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the degradation by reacting with carbonyl species (Liodakis et al. 2003). In earlier studies, analogous results for pyrolysis of Pinus halepensis pine needles were also attained by using the sodium phosphate salt, NaH2PO4 instead of ammonium phosphate salt, (NH4)2HPO4 (DAP), thus proving that ammonia has only a slight effect on degradation of bagasse compared to the phosphate entity (Liodakis et al. 1996). A new mass loss occurrence is also obvious between the temperature of 500– 750 °C at concentration of 0.5 and 1.0 M DAP (refer Fig. 7.2). A distinctive single peak is observed for 1 M DAP at around at 527 °C and a less distinctive peak around 715 °C for 0.5 M DAP. This occurrence has not been stressed in the previous literature reviewed, since the concentration of the additive was constant on lignocellusosic biomass. High DAP concentrations could possibly involve the creation of species that are resilient to thermal mass decomposition. Suardana et al. (2011) reported that when higher concentrations of the additive are used to treat biocomposites, it forms species such as phosphorous esters. From the experimental work shown in Fig. 7.2, the probable effect is that the quantity of these esters increases with higher concentration of DAP and the decomposition of these esters become apparent at high temperatures.

7.3.2

Char Yields of Bagasse with Catalyst Additives

Using the data from the TGA experiments, the char yields of bagasse treated with different concentrations of AS and DAP are calculated. Figure 7.3 and Table 7.3 show the char yields from the TGA experiments as evaluated at two temperatures at 450 and 700 °C. SCB treated with a concentration of 0.1 M for both AS and DAP seem to be the optimum concentration for the overall yields at both temperatures. In terms of the highest char yields, the lower temperature of 450 °C is more advantageous at the concentration of 1 M DAP and 0.1 M AS. A higher AS concentration (0.5 M and higher) loses its influence as a catalyst in the lower range temperatures since AS decomposes easily and sulphate gases are evolved. Similarly, high DAP concentrations (0.5 M and higher) drastically lowers the char yields at higher temperatures as the second mass loss event after 500 °C becomes substantial after this temperature at high concentrations (Fig. 7.3).

7.3.3

FTIR Spectroscopy Analyses for Gaseous Products

FTIR spectra was recorded for the gaseous products from raw bagasse, bagasse treated with AS and bagasse treated with DAP at various additions. Figure 7.4 shows the FTIR spectra of untreated bagasse at peak rate of mass loss events of 302 and 354 °C, respectively. The spectrum of untreated bagasse presents various absorbance peaks: in the wavenumber range of 2800–3000 cm−1 for hydrocarbon

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Table 7.3 Char yields (%) for pyrolysis of untreated and treated bagasse Material

450 °C

700 °C

Material

450 °C

700 °C

Untreated bagasse Bagasse + 0.01 M AS Bagasse + 0.05 M AS Bagasse + 0.1 M AS Bagasse + 0.5 M AS Bagasse + 1 M AS

21 27 34 38 36 27

17 20 27 29 27 18

Untreated bagasse Bagasse + 0.1 M DAP Bagasse + 0.5 M DAP Bagasse + 1 M DAP

21 47 51 58

17 39 26 31

Fig. 7.3 Char yields for pyrolysis of bagasse treated with AS and DAP

chains of alkanes and alkenes (aromatic and cyclic C–H is also present here); 2300– 2400 cm−1 for CO2 and range of 2100–2200 cm−1 for CO. Hydroxyl functional groups (–OH) are observed in the range of 3500–3650 cm−1, carbonyl functional groups (–C=O) of ketones and aldehydes are detected around 1700–1800 cm−1 and alkoxyl functional groups (–C–O–C–) of ethers in the range of 1300–1100 cm−1. In addition, there is evidence that aromatic rings are present, corresponding to absorptions in the region of 675 cm−1 due to bending vibrations of the C–H bonds of the aromatic ring as well as aromatic ring skeletal vibrations at around 1500– 1400 cm−1. The spectrum points towards the occurrence of CO, CO2, H2O and a series of alcohols, carboxylic acids and aldehydes/ketones/esters and ethers evolved from bagasse. It is not possible to differentiate whether an ester (a carbonyl component and ether component) or a ketone with an ether component is present since these functional groups show similar absorptions (Fig. 7.4). Comparing spectra at 302 and 354 °C in Fig. 7.5, there is a higher amount of C–H bonds (these include straight chains of alkanes, alkenes and aromatic and cyclic rings) at the second peak mass loss event of 354 °C. This is evident that more

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Fig. 7.4 IR spectra for gases formed from fresh untreated bagasse

gases evolve from pyrolysis at this mass loss event, as confirmed by the DTG plots. It is also observed that the peaks for ether/ester type C–O bonds in the region of 1000–1500 cm−1 is more conjoined, possibly due to higher quantity of these bonds at different absorption peaks existing at this temperature. The following FTIR spectra (refer Fig. 7.6) present the evolved pyrolysis gases measured from bagasse impregnated with 0.1, 0.5 and 1.0 M DAP with spectra recorded at peak of mass degradation events at 274, 267 and 266 °C, respectively. Some volatile products that contain N–H and N–O bonds, as well as peaks that are evidence of phosphorus esters, were present which indicates creation of new chemicals that are not detected in untreated bagasse. Since DAP produces an acidic environment, these chemicals are likely from the polymeric components that are cleaved off from bagasse (Tzamtzis et al. 1999). As the concentration of DAP increases, the concentration of the absorbance peaks (refer to Fig. 7.7) recorded for hydrocarbon stretch is diminished considerably. The hydroxyl functional group measured in the range of 3500–3700 cm−1 demonstrates a sequence of distinct peaks representing that water is the dominant compound in this part of the spectra. The concentration of the absorbance peaks for CO, CO2 and carbonyl/alkoxyl functional groups similarly reduce demonstrating a reduction in the quantity of organic volatile compounds evolved from bagasse. This reduction steadily increases with the increasing concentration of DAP thus the treatment is catalysing the dehydration reactions during pyrolysis, which increases H2O formation and increases the char yield by decreasing the volatile components (Figs. 7.6 and 7.7).

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Fig. 7.5 Comparison of absorbance of untreated bagasse at peak temperatures

Fig. 7.6 IR spectra for gases formed from treated bagasse with 0.1, 0.5 and 1 M DAP at peak first mass degradation event

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Fig. 7.7 Comparison of absorbance of evolved gases for various DAP concentrations at peak temperatures

The spectrum in Fig. 7.8 presents the pyrolysis gases measured from bagasse impregnated with 1.0 M DAP about the peak mass loss (second mass loss event) at 527 °C. A second mass loss is also evident (refer Fig. 7.2) in bagasse impregnated with 0.5 M DAP, however, the peak is not clearly formed. Comparing spectra for bagasse impregnated with DAP for the first and second mass loss; there is a noticeable absence of any central peaks in the 1700 cm−1 region that corresponds to carbonyl functional groups. The hydroxyl functional groups in bagasse may possibly be interchanged by phosphate groups producing phosphorus esters (Suardane et al. 2011). Absorbance peaks between the ranges of 1000–1450 cm−1 are consistent with the IR spectra of esters of phosphoric acid. A comprehensive band over the 3000–3500 cm−1 range is representative of phenyl and unsaturated phosphonic acid as well as N–H group at around 3200 cm−1 from ammonia (Suardane et al. 2011; Fig. 7.8). The FTIR spectra in Fig. 7.9 present the evolved pyrolysis gases measured from bagasse impregnated with 0.05, 0.1, 0.5 and 1.0 M AS. The spectra was recorded about the peak of mass degradation events at 240, 240, 228 and 229 °C, respectively. The bagasse treated with AS follows a similar trend to bagasse treated with DAP. However, bagasse treated with AS is observed to show compounds with absorbance peaks corresponding to S=O bonds. The peak that corresponds to sulphur-related esters occurs in the range of 700–900 cm−1, which is strongly present at 755 cm−1. The peaks in the range of 1300–1400 cm−1 (asymmetrical S=O) correspond to sulphur dioxide as well as to sulphones (–R2–S–O2), the peaks

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Fig. 7.8 IR spectrum for gases formed from treated bagasse with 1 M DAP at peak second mass degradation event

Fig. 7.9 IR spectra for gases formed from treated bagasse with 0.05, 0.1, 0.5 and 1 M AS at peak of first mass loss event

at around 1150 cm−1 correspond to symmetrical S=O bands. The peaks at around 1450 cm−1 correspond to sulphate species (SO42−). These sulphur compounds are most likely produced from the interaction between the bagasse and AS (Fig. 7.9).

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Comparing absorbance peaks in Fig. 7.10 shows that as the concentration of AS increases, the concentration of the absorbance peaks recorded for hydrocarbons in the range 3000 cm−1 is diminished considerably. The hydroxyl functional group measured in the range of 3500–3700 cm−1 demonstrates a sequence of distinct peaks representing that water is the dominant compound in this part of the spectra. The concentration of the absorbance peaks for CO, CO2 and carbonyl/alkoxyl functional groups similarly reduce demonstrating a reduction in the quantity of organic volatile compounds evolved from bagasse (Fig. 7.10). The FTIR spectrum in Fig. 7.11 present the evolved pyrolysis gases measured from bagasse impregnated with 0.5 and 1.0 M AS and the spectra were recorded at about the peak mass loss at 337 and 357°C, respectively. There is a noticeable absence of peaks in the 3500–3700 cm−1 region—water is still present, however, the peaks are masked by the high absorbance of other major bands. The peak between the ranges of 1300–1400 cm−1 shows very high absorbance peaks which correspond to SO2. The fingerprint region around the 1200–900 cm−1 range is very difficult to pinpoint for this mass loss event but they correspond to S–O bands. These S–O bands agree with organo-sulfonate components. A wavenumber range of 2400–2300 cm−1 for CO2, range of 2200–2100 cm−1 for CO is still persistent for this mass loss, however, the absorbance of hydrocarbon chains are much lower at these concentrations of AS at this temperature. There is a definite lack of bands that correspond to C=O carbonyl functional groups which may suggest, at high concentration of AS, the evolution of these volatile components are already accelerated at lower temperatures.

Fig. 7.10 Absorbance of evolved gases at various AS concentrations and temperatures

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Fig. 7.11 IR spectra for gases formed from treated bagasse with 0.5 and 1 M AS at peak of second mass degradation event

Fig. 7.12 Comparison of absorbance of evolved gases for 0.5 M and 1 M AS treated bagasse at peak mass loss

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Comparing absorbance peaks to those in Fig. 7.12 shows as the concentration of AS increases, the concentration of the absorbance peaks for CO, CO2 and SO2 increase at higher concentrations demonstrating a disruption in the quantity of organic volatile compounds evolved from bagasse. However, since the production of SO2 is much higher than expected, it is probable that the catalytic effect of AS is less active at concentrations higher than 0.5 M (Figs. 7.11 and 7.12).

7.4

Conclusions

Literature resources show that the pyrolysis of SCB to produce biochar and activated carbons show similar surface areas as commercially produced activated carbons with high dye adsorption capacities. However, production of activated carbons is economically marginal when compared with the price of bulk activated carbons although SCB-sourced activated carbons may be suitable for niche applications. To improve the yield of biochar from pyrolysis of SCB the additives ammonium sulphate (AS) or diammonium phosphate (DAP) may be used to pretreat the SCB. The enhancement in biochar formation for the DAP additive can be summarised as an outcome of an act of phosphorous compounds acting as catalysts in the dehydration of the bagasse components by diminishing the formation of organic volatile compounds. For AS, the decomposition of ammonia and sulphuric acid also plays a role in the char yield, however, it is not as prominent as for the additive DAP. The ammonia in both AS and DAP slightly increase the formation of char by reacting with intermediate carbonyl compounds. At high temperatures (>500 °C), and high DAP concentration (>0.5 M), a second mass loss event is evident which reduces the char yield. Similarly, for high concentrations of AS (>0.5 M) at temperatures around 350 °C, sulphuric acid decomposes to sulphur dioxide, which reduces catalytic activity and demonstrates that catalytic activity of AS is higher at lower concentrations. Use of DAP or AS additives increase the potential char yield from *20% (untreated SCB) to highs of 58 and 38% respectively. If this increase in yield of char can be achieved while maintaining char adsorption of dyes this may make such chars economically competitive with currently available commercial chars.

References Amin, N. K. (2008). Removal of reactive dye from aqueous solutions by adsorption onto activated carbons prepared from sugarcane bagasse pith. Desalination, 223, 152–161. Balakrishnan, M., & Batra, V. S. (2011). Valorization of solid waste in sugar factories with possible applications in India: A review. Journal of Environmental Management, 92, 2886–2891.

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Beeharry, R. P. (1996). Extended sugarcane biomass utilisation for exportable electricity production in mauritius. Biomass and Bioenergy, 11(6), 441–449. Beeharry, R. P. (2001). Strategies for augmenting sugarcane biomass availability for power production in Mauritius. Biomass and Bioenergy, 20(6), 421–429. Carrier, M., Hugo, T., Gorgens, J. & Knoetze, H. (2011). Comparison of slow and vacuum pyrolysis of sugar cane bagasse. Journal of Analytical and Applied Pyrolysis, 90(1), 18–26. Changpeng, K. L., Liqiang, Z., & Xifeng, Z. (2016). Study on pyrolysis characteristics of lignocellulosic biomass impregnated with ammonia source. Bioresource Technology, 209, 142–147. Chen, M. Q. (2008). Catalytic effects of eight inorganic additives on pyrolysis of pine wood sawdust by microwave heating. Journal of Analytical and Applied Pyrolysis, 82, 145–150. Collard, F. X., J. Blin, Bensakhria, A., & Valette, J. (2012). Influence of impregnated metal on the pyrolysis conversion of biomass constituents (Vol. 95, pp. 213–226). da Gonçalves, G. C., Pereira, N. C., & Veit, M. T. (2016). Production of bio-oil and activated carbon from sugarcane bagasse and molasses. Biomass and Bioenergy, 85, 178–186. Di Blasi, C., Branca, C., & Galgano, A. (2007). Effects of diammonium phosphate on the yields and composition of products from wood pyrolysis. Industrial & Engineering Chemical Research, 46, 430–438. Eom, I. Y., Kim, J. Y., Kim, T. S., Lee, S. M., Choi, D., Choi, J. G., et al. (2012). Effect of essential inorganic metals on primary thermal degradation of lignocellulosic biomass. Bioresource Technology, 104, 687–694. FAO. (2015). FAO statistical handbook. World food and agriculture. Food and Agriculture Organization of the United Nations, Rome, 2015. Fu, Q., Argyopoulos, D. S., Tilotta, D. C., & Lucia, L. A. (2008). Understanding the pyrolysis of CCA-treated wood Part I. Effect of metal ions. Journal of Analytical Applied Pyrolysis, 81, 60–64. Garrett, B., Shorofsky, B., & Radcliffe, R. (2012). Evaluation of textile treatment and treatment alternatives for the village of Jasol in Rajasthan, India. Jal Bhagirathi Foundation and the Northwestern University Global and Ecological Health Engineering Certificate Program. Griffin, G. J. (2011). The effect of fire retardants on combustion and pyrolysis of sugar-cane bagasse. Bioresource Technology, 102, 8199–8204. Griffin, G. J., Tan, L. C. K., Ho, L. K., & Pannirselvam, M. (2015). Conversion of bagasse to char-water fuel by pyrolysis. Energy and Sustainability VI, 39. Hu, S., Jess, A., & Xu, M. (2007). Kinetic study of Chinese biomass slow pyrolysis: Comparison of different kinetic models. Fuel, 86, 2778–2788. Jaguaribe, E. F., Medwiros, L. L., Barreto, M. C. S., & Araujo, L. P. (2005). The performance of activated carbons from sugarcane bagasse, babassu, and coconut shells in removing residual chlorine. Brazilian Journal of Chemical Engineering, 22(1), 41–47. Liodakis, S., Bakirtzis, D., & Dimitrakopoulos, A. P. (2003). Autoignition and thermogravimetric analysis of forest species treated with fire retardants. Thermochimica Acta, 399, 31–42. Liodakis, S. E., Statheropoulos, M. K., Tzamtis, N. E., Pappa, A. A., & Parissakis, G. K. (1996). The effect of salt and oxide-hydroxide additives on the pyrolysis of cellulose and Pinus halepensis pine needles. Thermochimica Acta, 278, 99–108. Low, L. W., Teng, T. T., Ahmad, A., Morad, N., & Wong, Y. S. (2011). A novel pretreatment method of lignocellulosic material as adsorbent and kinetic study of dye waste adsorption. Water, Air, and Soil pollution, 218, 293–306. Low, L. W., Teng, T. T., Morad, N., & Azahari, B. (2012). Studies on the adsorption of methylene blue dye from aqueous solution onto low-cost tartaric acid treated bagasse. APCBEE Procedia, 1, 103–109. Manya, J. J., & Arauzo, J. (2008). An alternative kinetic approach to describe the isothermal pyrolysis of micro-particles of sugar cane bagasse. Chemical Engineering Journal, 139(3), 549–561.

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Ng, C., Marshall, W., Rao, R. M., Bansode, R. R., Losso, J. N., & Portier, R. J. (2003). Granular activated carbons from agricultural by-products: Process description and estimated cost of production. Bulletin Number 881, LSU AgCentre, Baton-Rouge, August 2003. Pappa, A. A., Tzamtzis, N. E., Statheropoulos, M. K., Liodakis, S. E., & Parissakis, G. K. (1995). A comparative study of the effects of fire retardants on the pyrolysis of cellulose and Pinus halepensis pine-needles. Journal of Analytical and Applied Pyrolysis, 31, 85–100. Sekiguchi, Y., & Shafizadeh, F. (1984). The effect of inorganic additives on the formation, composition, and combustion of cellulosic char. Journal of Applied Polymer Science, 29(4), 1267–1286. Shen, J., Zhu, S., Liu, X., Zhang, H., & Tan, J. (2010). The prediction of elemental composition of biomass based on proximate analysis. Energy Conversion and Management, 51, 983–987. Statheropoulos, M., & Kyriakou, S. A. (2000). Quantitative thermogravimetric-mass spectrometric analysis for monitoring the effects of fire retardants on cellulose pyrolysis. Analytica Chimica Acta, 409, 203–214. Suardane, N. P. G., Ku, M. S., & Lim, J. K. (2011). Effects of diammonium phosphate on the flammability and mechanical properties of bio-composites. Materials and Design, 32(4), 1990–1999. Tahir, H., Sultan, M., Akhtar, N., Hameed, U., & Abid, T. (2016). Application of natural and modified sugar cane bagasse for the removal of dye from aqueous solution. Journal of Saudi Chemical Society, 20, S115–S121. Tsai, W. T., Chang, C. Y., Lin, M. C., Chien, S. F., Sun, H. F., & Hsieh, M. F. (2001). Adsorption of acid dye onto activated carbons prepared from agricultural waste bagasse by ZnCl2 activation. Chemosphere, 45, 51–58. Tzamtzis, N., Pappa, A., & Mourikis, A. (1999). The effect of (NH4)2HPO4 and (NH4)2SO4 on the composition of the volatile organic pyrolysis products of Pinus halepensis pine-needles. Polymer Degradation and Stability, 66, 55–63. Valix, M., Cheung, W. H., & McKay, G. (2004). Preparation of activated carbon using low temperature carbonisation and physical activation of high ash raw bagasse for acid dye adsorption. Chemosphere, 56, 493–501. Williams, P. T., & Home, P. A. (1994). The role of metal salts in the pyrolysis of biomass. Renewable Energy, 4(1), 1–13.

Chapter 8

Disinfection By-products in Recycled Waters Lydon D. Alexandrou, Barry J. Meehan and Oliver A. H. Jones

Abstract Disinfection is an integral component of water treatment performed on large volumes of water worldwide. Chemical disinfection may, however, result in the unintended production of disinfectant by-products (DBPs) due to reactions between disinfectants and organic matter present in the source water. Due to their toxicity, levels of DBPs have been strictly regulated in drinking waters for many years. With water reuse becoming more common around the world, DBPs are now increasingly becoming a concern in recycled waters, where a much larger amount and variety of compounds may be formed due to higher abundance of organic material in the source water. With increasing temperatures and population growth in future, there is an increased need to make greater use of waste/recycled water to supplement supplies in countries such as Australia. This, in turn, necessitates a greater understanding of DBP formation in waste and recycled waters. Keywords Chlorination Toxicity

8.1


Natural organic matter
Pollution
Recycled water

General

Recycled water is often thought as a modern phenomenon but, think about it, and it can be seen that the recycling of water is actually a natural process that has been happening for millennia. Most people will, for example, be familiar with the simplified water cycle taught in schools with water evaporating from the sea to form clouds, which move over land with the water then falling as rain into lakes, streams L. D. Alexandrou
O. A. H. Jones (&) Australian Centre for Research on Separation Science, School of Science, RMIT University, GPO Box 2476, Melbourne, VIC 3001, Australia e-mail: [email protected] L. D. Alexandrou
B. J. Meehan
O. A. H. Jones Water: Effective Technologies and Tools (WETT) Research Centre, School of Science, RMIT University, GPO Box 2476, Melbourne, VIC 3001, Australia © Springer International Publishing AG, part of Springer Nature 2019 M. Pannirselvam et al. (eds.), Water Scarcity and Ways to Reduce the Impact, Applied Environmental Science and Engineering for a Sustainable Future, https://doi.org/10.1007/978-3-319-75199-3_8

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Fig. 8.1 Typical urban water cycle

and rivers and moving back to the sea. A more representative water cycle takes into account the fact that much of the water that falls as rain is collected and diverted for use in cities and towns as well as industry and agriculture before it is returned to the environment. It is usually (though not always) treated prior to the latter stage. The water you drink today has been ‘recycled’ many times before it got to you and it will be recycled again and again in future. A simple diagram outlining the typical urban water cycle can be seen in Fig. 8.1. Notwithstanding the above, not all parts of the world are equally rich in water and those places where water is plentiful are not always those where people want to live. As human populations increase in water-stressed areas, there is not always enough freshwater to supply all needs. Recycled water is, therefore, a topic of increasing interest and importance in countries such as Australia and even in dry parts of countries usually considered as water-rich (e.g. East Anglia in the UK). Presently, the application of recycled waters is limited to uses that don’t include direct human consumption, such as watering playing fields and filling municipal fountains. In Australia, pipes that deliver recycled water are of different colour, size and diameter than standard pipework in order to minimise the chance of cross connections and this has lead to general acceptance of the use of recycled water as long as it is kept out of the home. It may not be possible to keep this restriction in future years due to the increasing occurrence of drought conditions, coupled with lower rainfall and even lower catchment replenishment rates. The prevailing water management strategy of relying on current water storage facilities and high rainfall events is likely to be unsustainable in the long run and there are concomitant worries that over-abstraction from groundwater will cause serious damage to an already fragile environment. Water recycling has thus been, and will likely remain, an issue in Australia for the foreseeable future. There are two main mechanisms that can be used to increase the total amount of usable water available—wastewater treatment (which treats sewage) and desalination (which treats saltwater). Both involve substantial, multistage processes with the raw influent undergoing, physical, biological and chemical treatments before being

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distributed to where it is needed. These processes have significant environmental impacts but both produce usable product. While desalination produces potable water that is generally accepted by the public, there is a general stigma associated with the term ‘wastewater’, which precludes its use as drinking water directly in many countries; the effluent instead being taken as the influent for a drinking water plant to ensure it is of a suitable standard. A notable example is ‘NEWater’, which is high-grade reclaimed water and a pillar of Singapore’s water sustainability strategy. During dry periods, NEWater is added to reservoirs and blended with raw water. The water from the reservoir is treated at the waterworks before it is supplied to consumers as tap water. In Australia, water treatment plants will often process influent to either class A, B, C or D standard, depending upon its intended use. What is termed ‘class A’ usually meets the standards for drinking water but even so it is restricted to uses such as industrial coolant, the watering of non-food crops and residential uses such as toilet flushing and washing of cars and boats. All instances that will ensure little to no human exposure for any possible adverse effects from the treated wastewater. Nevertheless, it has been shown that small volumes (0.06–3.79 mL) of recycled water can be inadvertently ingested from spray exposures, during car washing for example, so it is important to be vigilant (Sinclair et al. 2016). To move towards future, broader reuse, including drinking, of treated wastewater, there has been a push to apply very advanced drinking water treatments to remove organic micropollutants such as endocrine disrupting compounds (EDCs), personal care products (PCPs), per-fluorinated compounds (PFCs), pharmaceuticals (including iodinated X-ray contrast media), illicit drugs, and pesticides from wastewater. As shown by Jones et al. (2007), such methods can have a high environmental and financial cost. They are considered necessary, however, to reassure the public of the removal of all contaminents (either as the parent compounds or as metabolites and/or breakdown products) originating from the influent wastewater. Such methods are usually very successful. However, sometimes they can introduce problems as well as remove them. Once such example is disinfection via chlorination. This is often one of, if not, the last step in water treatment prior to distribution but can lead to the formation of Disinfectant By-Products (DBPs).

8.2

Disinfection

Chemical disinfection is performed daily on large volumes (gigalitres) of water around the world. It usually involves one of three processes, Chlorination, Chloramination or Ozonation; it is common practice to use a mixture of two or more of these methods. Chlorination was first used in 1908 in New Jersey (USA) (Ivanhenko and Zogorski 2006) and is still the most commonly used disinfection mechanism for water treatment. However, in addition to disinfecting the source water, chemical disinfection may result in the production of DBPs via

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substitution reactions with organic matter present in the source water (McCormick et al. 2010). The formation of DBPs in drinking water was predicted back in the 1970s and, as many DBPs are toxic, background levels of these compounds in drinking water are strictly monitored and regulated. Research into DBP formation and presence in wastewater is much more limited. This is an area where much more research is needed since raw wastewater generally has a greater amount and range of organic matter than river or lake water and thus the potential for the formation of a large amount of correspondingly diverse DBPs is high. DBPs also form in swimming pools as a result of chlorination but this is outside the scope of the present work and will not be discussed further. Instead, this chapter will outline the implications of DBPs in wastewater, shedding some light on their occurrence and how they can be measured.

8.3

Disinfection By-products

Since DBPs are formed as the result of the disinfection process, particularly the chemical disinfection stage, of tertiary water treatment they are one of the very few water pollutants whose concentrations go up at the end of the treatment stage rather than down. The most commonly formed are small halogenated compounds of below 200 amu. DBPs are, however, not limited to small, nor halogenated compounds, with some compounds, for example, being nitrogenated in the presence of chloramine. Due to the complex nature of wastewater, the type and number of compounds that can form is almost endless, however, due to their trace quantities and/or further breakdown after formation, there have only been *600 compounds identified as DBPs. The most commonly occurring classes are the trihalomethanes (THMs), haloacetic acids (HAAs), haloketones (HKs) and oxyhalides (Zhang et al. 2004). There are also newer classes of DBPs such as nitrosamines and halobenzoquinones. Most compounds in each class are very similar usually differing only in how halogenated they are. The structure of selection of a range of the main DBPs is shown in Fig. 8.2. It can be seen from Fig. 8.2 that DBPs come in a wide variety of shapes and sizes and this makes them a tough group to analyse for, especially as many of the classes require highly specific analytical and extraction methods. This has meant that analysis of individual compounds is generally limited with most studies focussing on reporting the total amount of a particular groups or groups, e.g. total THMs, with occasional forays into new and emerging DBPs as and when they are found. There has been a steady monitoring regime for those DBP compounds, which have set regulatory limits but these are limited to a rather small pool of 14 compounds (whose drinking water limits are applied to treated wastewater) that have the highest formation potential, and likely concentration. Again, compound groups,

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Fig. 8.2 Structures of some common DBPs

rather than individual compounds, are generally measured e.g. trichloromethane, bromodichloromethane, dibromochloromethane and tribromomethane, are commonly reported as a sum value of total trihalomethanes (TTHMs), without indicating, or indeed taking into account, the possibility of iodinated or brominated

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Fig. 8.3 Chromatogram of class A water. Vertical dotted lines show the retention time of the four THMs analysed (from left to right TCM, BDCM, DBCM and TBM). The overall average of total THM concentration in Class A water was 17.03 µg/L with specific compound levels as follows— TCM 7 ± 2 µg/L, BDCM 5.2 ± 0.2 µg/L, DBCM 4.83 ± 0.08 µg/L (see Fig. 8.3). These levels are well below the Australian guideline limit for TTHMs of 250 µg/L and below the US EPA limit of 80 µg/L

species being present. The increasing creation and use of recycled water in many areas of the world means that the development of new, fast and economical methods for the extraction and detection of DBPs from a range of aqueous samples is of interest, particularly in countries such as Australia, where water recycling is extensively practised. Disinfection by-products have been found to be present in class A water (as shown in Fig. 8.3). Since DBPs are usually small, highly halogenated, volatile organic compounds (VOCs), gas chromatography (GC) with either electron capture detection (ECD) or mass spectrometry (MS) is typically used for their analysis, with other instrumentation such as high-performance liquid chromatography (HPLC) or ion chromatography (IC) being used in specialised cases. Before the sample can be analysed, the DBPS must usually be extracted and pre-concentrated. Extraction methods are where the greatest variation in methodology arises with the use (and optimisation) of a variety of sorbents, solvents and chemical additions required to suit the target analytes (Alexandrou et al. 2015). The most common extraction methods are solid-phase microextraction, solid-phase extraction, liquid–liquid extraction and purge and trap extractions. Some analytes require a derivitization step dependant on the instrumental analysis used. While there are many available standard methods for the analysis of commonly occurring DBPs, there are fewer methods for new and emerging compounds. In order to develop such methods, it is useful to understand how such compounds are formed.

8.3.1

Formation

The major formation pathways of DBPs are the interactions between the disinfectants used and natural organic matter (NOM) in the source water. A typical

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influent for water treatment is surface water and the NOM in this matrix is comprised mainly of humic and fulvic acids. A much wider range of organic matter makes up the NOM fraction in wastewater. This may include compounds from natural and anthropogenic sources including amino acids, carbohydrates, proteins, pharmaceuticals, illicit drugs and other organic compounds (Wang et al. 2013; Huerta-Fontela et al. 2012; Postigo and Richardson 2014). As mentioned earlier, the overlapping of NOM and effluent organic matter present during wastewater treatment enhances and increases the total DBP formation potential when compared to drinking waters. Although the NOM fraction is the greatest contributor to the formation potential of DBPs, organic matter is not the only factor that affects their formation. General water quality parameters also play a part. This includes factors such as pH, temperature and the presence of free/dissolved chlorine, bromine, iodine and nitrogen. As a result of this, water quality parameters make up many published formation potential models. Of the classified DBPs, the most commonly formed class are the trihalomethanes, specifically those that make up the TTHM measurement. The chlorinated THM species have a higher formation potential, compared to that of other halogenated methanes. Not to be forgotten are the brominated and iodinated species, which occur at lower concentrations than the chlorinated species due to their formation being prerequisite on the source water containing free bromine or free iodine. Iodinated DBPs occur less often than other DBP species, due to the negligible concentrations of dissolved iodine in source waters, though with recent improvements/changes to some industrial processes, particularly the presence of iodinated X-ray contrast media in hospital wastewater (Duirk et al. 2011) and dairy farms (Hladik et al. 2016), there is an increasing formation rate of iodinated DBPs being reported. Brominated species are also rare but are increasingly found in wastewater influents associated with fossil fuel extraction (Parker et al. 2014). Bromine is also present in seawater and so brominated DBPs are a concern in desalinated water if it is disinfected/chlorinated (Liu et al. 2015; Manasfi et al. 2016). Another major formation pathway, which plays a large role in the formation of trihalomethanes is the degradation of other compounds. Classes such as haloacetic acids and haloacetonitriles have been shown to break down, reacting with residual free chlorine to form trihalomethanes under ambient water conditions through a decarboxylation pathway (Zhang and Minear 2002). In general, THM levels tend to increase with pH, temperature, time, and the level of ‘precursors’ present (Garcia-Villanova et al. 1997). Other readily forming DBPs are the haloacetic acids. The formation potential of this group increases significantly with greater concentrations of free chlorine. Five compounds from this group occur most often (once again dominated by the chlorinated species). These are monochloroacetic acid (MCAA), dichloroacetic acid (DCAA), trichloroacetic acid (TCAA), monobromoacetic acid (MBAA) and dibromoacetic acid (DBAA). Variations on these molecules, where chlorines are

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substituted for bromine or iodine occur less frequently and are dependant on the influent source and the amount of free chlorine present. The haloacetic acids are highly polar and less volatile than trihalomethanes and are therefore more susceptible to dissolution or decomposition to simpler compounds, under favourable conditions (Zhang and Minear 2002). Aside from two classes discussed above, which are recognised as the more common DBPs, the formation potentials of other species are highly dependant on the treatment conditions employed. Compounds such as oxyhalides, for example, are more prevalent in drinking water in cases where ozonation is used alongside chlorination (von Gunten 2003). In the presence of a lower organic matter content, the simple oxyhalides are formed readily and in measurable concentrations. The more common oxyhalides that are monitored regularly in drinking water are chlorite and bromite, with others such as chlorate, perchlorate, chloride, bromate and bromide along with nitrogenated analogues also often tested for (Bellar et al. 1974). Nitrosamines are a new class of emerging DBPs that are formed in a similar manner to the halogenated DBPs but lack a halogen in their structure. Instead, are formed through reactions between secondary or tertiary amines and a nitrosating agent (e.g. chloramine). The formation pathways of these and many other nitrogenous DBPs have been of strong interest for many years. The group has been shown to have many precursor compounds, many of which have pharmaceutical or industrial origins. Nitrosamines are therefore more prevalent in treated wastewaters fed by industry-based sources. Examples of these precursors are ranitidine, nizatidine, doxylamine, trimethylamine and glycine (Bond et al. 2012). After formation, nitrosamines are difficult to be extracted or removed due to their polarity and relatively low log Kow coefficient, they are, however, rarely present above low part per thousand concentrations. The above only covers a very small fraction of the total identified DBPs. Almost any organic compound or class can form a DBP with the same basic pathway of a substitution or addition of a halogen to the basic molecular structure. The increasing variability of influent composition in conjunction with the diversity of the disinfection processes being undertaken acting as the major driver for the diversity seen among DBPs. This is further exacerbated by current trends to alter the amounts of disinfectants used (in an attempt to reduce the overall formation of specific compounds) coinciding with alternate chemicals used within industry, influencing the influents composition. As long as this trend continues, there will be a need to analysis treated waters for the presence of common DBPs along DBPs derived from contaminants of emerging concern. Of particular interest are the halofuranones, whose genotoxic and carcinogenic properties are well established (Kubwabo et al. 2009). The major halofuranone is 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)furanone, or more commonly known as Mutagen X (Suzuki and Nakanishi 1995). This compound has been found on multiple occasions at ppt levels (Andrzejewski and Nawrocki 2005; Kronberg et al. 1988; Kubwabo et al. 2009).

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143

Toxicology

There is a long history of toxicological testing for many DBPs of potential concern in drinking water, and this means that there are readily available risk assessments for the most commonly occurring compounds. The large gap in knowledge for the occurrence of many DBPs does, however, mean that regulatory limits are only set for 11 compounds in Australia and elsewhere, although the World Health Organization (WHO) has recently increased this to 14 compounds. A list of regulated compounds and their relative limits is given in Table 8.1. Comparing the regularity limits set globally, it is clear that there are major discrepancies between governing bodies, with differences of *200 ppb in one case. Using these regulatory limits for wastewater is not, however, strictly correct as they are set for drinking water, taking into account only the appropriate exposure for humans for each regulated compound. The belief being that there is little to no human exposure to treated wastewater means that the devised guidelines are a baseline that is often not enforced. This situation would have to change if recycled water was to be used in the home directly. Table 8.1 Current regulatory limits for DBPs as set by major water governing bodies. Greater summary can be found in a review by Wang et al. (2015) Compound class

Major studied

Regulatory guidelines (mg/L) US.EPA WHO AUS (NHMRC)

Oxyhalides

Chlorite Chlorate Bromate Trichloromethane (Chloroform) Bromodichloromethane Dibromochloromethane Tribromomethane (Bromoform) Trichloronitromethane (Chloropicrin) Monochloroacetic acid Dichloroacetic acid Trichloroacetic acid Monobromoacetic acid Dibromoacetic acid Dichloroacetonitrile Dibromoacetonitrile N-Nitrosodimethylamine (NDMA)

1 – 0.01 (TTHM) 0.08

Trihalomethanes

Halonitromethanes Haloacetic acids

Haloacetonitriles Nitrosamines

0.7 0.7 0.01 0.3

0.8 ND 0.02 (TTHM) 0.25

0.06 0.1 0.1 –

–

0.08

(HAA5) 0.06

0.02 0.05 0.2 – – 0.02 0.07 0.0001

0.15 0.1 0.1 – – – – 0.0001

– – –

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In Australia, the current drinking water limit for THMs was set at 250 µg/L by National Health and Medical Research Council and Agriculture and Resource Management Council of Australia and New Zealand (NHMRC/ARMCANZ) in 2011 (NHMRC 2011). This limit is one of the highest in use worldwide; for comparison, the limit set by the United States Environmental Protection Agency (EPA) is only 80 µg/L (Wang et al. 2015). The toxicity of DBPs can generally be assigned to one of three general classes; (i) those showing some or all of the characteristics of human carcinogens, (ii) those that are genotoxic and (iii) those that have little to no toxicological data available. The majority of DBPs fall into the third category. There is a general trend of increasing toxicity of iodinated > brominated > chlorinated, and brominated species are often more genotoxic than the chlorinated species (Grellier et al. 2015). There is also a trend of increasing toxicity with increasing level of halogenation (Richardson et al. 2007). All regulated DBPs show some level of toxicity, with many having mutagenic effects above a specific threshold when tested with mammalian cells (Richardson et al. 2007). For unregulated DBPs, there is still a lack of data as to toxicity at relevant concentrations and exposure pathways (e.g. bathing, swimming and showering through dermal inhalation or exposure). The environmental toxicity of DBPs is unknown but thought to not be a large issue due to the majority of commonly occurring compounds being highly volatile and non-bioaccumulating. Other contaminants in treated wastewaters are much more of a worry environmentally speaking. Although many DBPs can be readily absorbed or ingested, most are broken down or excreted quickly and have negligible effects on the ecosystem as a whole.

8.3.3

Occurrence

Although DBPs are widely studied, occurrence research is typically limited to the analysis of drinking water sources. Research is also centred around the regulated and the more common DBPs, not emerging compounds or groups. In the case of the drinking water, DPP occurrence can be obtained simply through the annual reports issued by the water companies, which are required to provide information that proves their compliance with the respective regulatory limits. This information may, however, not always be the best source of occurrence data as it does not generally report the day to day concentrations or even seasonal variation. Typical representation of the data may range from stating it is below a given concentration, usually the defined limit, or a stated average. Coupling this with the fact that information for the regulated DBPs is given for total trihalomethanes (the sum of the four compounds) and total haloacetic acids, (the sum of five, six or nine haloacetic acids depending on the analyses undertaken) means detailed data is not common. Rarely are values given for a singular compounds unless they are the only regulated compound in a given class.

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For recycled waters, the story is completely different. Due to limited human impact and a lack of proven environmental impact, wastewater analyses are rarely performed, and when they are never tested on a scale such as that of drinking water treatment plants. In the event that wastewater treatment plants are studied the relevant reports often lack detail. Of those reports that are published, DBP levels are rarely above the regulatory limits, typically at low part per billion (ppb) or part per thousand (ppt) levels, with very rare cases up to 500 ppb. In one study in Victoria, Australia, however, levels of four trihalomethanes were measured in water from a sewage treatment plant in Melbourne, from September to October 2013 (Alexandrou et al. 2015). The targeted compounds were chloroform, bromodichloromethane, dibromochloromethane and bromoform. Gas Chromatography with microelectron capture detection used to identify the target compounds. Total trihalomethane levels in the wastewater were found to be 17 ± 2 µg/L. The dominant species was TCM with a concentration of 7 ± 2 µg/L but no TBM was observed in any of the samples (levels shown in Fig. 8.4). The results demonstrate that disinfection by-products were present in the treated wastewater from the plant and that they are introduced via the chlorination process itself rather than from a source in the catchment. The largest increase in concentration before and after chemical disinfection was observed with TCM, which increased from *1.2 to *7.2 µg/L. Similar trends were observed for BDCM and DBCM and support the theory that the use of chlorination as the treatment process yields TCMs with higher concentrations of chlorinated than brominated species when compared to the use of alternative methods such as chloramination (Tian et al. 2013). The exception being that TBM is the major species in the presence of high concentrations of Br. The concentration

Fig. 8.4 Analyte occurrence throughout wastewater treatment at the plant studied

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Table 8.2 Concentrations of DBPs observed in both wastewater and drinking water from various countries as reported in the literature Wastewater (µg/L) AUS–QLD (Watson et al. 2012) TCM BDCM DBCM TBM TTHM Drinking

AUS–WA (Allard et al. 2012)

– 0.34 – 0.05 – 0.035 – 0.03 46–279 0.46 water (µg/L) AUS–VIC USA (SEWater (Weinberg 2013) et al. 2002)

USA (Krasner et al. 2009)

NE Spain (Matamoros et al. 2007)

Greece (Nikolaou et al. 2002)

Iran (Hassani et al. 2010)

– – – – 11–92

– – – – 4.25–54.5

nd–458.5 nd–5.8 nd–9.7 – –

– – – – 5.97–6.05

UK (Whitaker et al. 2003)

Canada (Koudjonou et al. 2008)

Korea (Cho et al. 2003)

China (Gan et al. 2013)

5.38– 13.34 4.55–9.02 1.02–2.28 0.09–0.19 11.04– 24.03

–

TCM

6–83

1–45

17.9–38.1

2.6–15.6

BDCM DBCM TBM TTHM

3–25 nd–14 nd–1 11–107

1–40 nd–25 nd–19 4–99

6.4–8.1 2.4–5.3 1.8–2.4 28.5–53.9

4.8–13.1 2.0–43.7 nd–39.1 16.4–99.6

– – – 1.8–33.4

– Indicates no available published data NB Data for drinking water were selected from the most up to date reports available

of TCM fluctuated between samples indicating some variation in the formation/ detection for the duration of the sampling period.

8.4

Conclusions

THM levels in the wastewater analysed are similar to drinking water levels with a few exceptions, as shown in Table 8.2. There is a limited amount of information available on the occurrence of THMs in wastewater around the world. As treated wastewater is increasingly used in agriculture, industry and in some areas for potable supply there is a need to investigate the environmental problems that may arise from elevated THM levels along with many other harmful DBPs, which are emerging as a result of alternative treatment methods. In future, as the use of recycled water increases, it would be helpful if research is carried out over a large span of time, looking at both multiple treatment plants and multiple stages of treatment. This will allow a standard mass balance to be completed, whilst also pinpointing the stages in treatment that increase or reduce total DBP concentrations

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Tian, C., Liu, R., Guo, T., Liu, H., Luo, Q., & Qu, J. (2013). Chlorination and chloramination of high-bromide natural water: DBPs species transformation. Separation and Purification Technology, 102, 86–93. https://doi.org/10.1016/j.seppur.2012.09.034. von Gunten, U. (2003). Ozonation of drinking water: Part II. Disinfection and by-product formation in presence of bromide, iodide or chlorine. Water Research, 37, 1469–1487. https:// doi.org/10.1016/s0043-1354(02)00458-x. Wang, J. J., Liu, X., Ng, T. W., Xiao, J. W., Chow, A. T., & Wong, P. K. (2013). Disinfection byproduct formation from chlorination of pure bacterial cells and pipeline biofilms. Water Research, 47, 2701–2709. https://doi.org/10.1016/j.watres.2013.02.038. Wang, X., Mao, Y., Tang, S., Yang, H., & Xie, Y. (2015). Disinfection byproducts in drinking water and regulatory compliance: A critical review. Frontiers of Environmental Science & Engineering, 9, 3–15. https://doi.org/10.1007/s11783-014-0734-1. Watson, K., Shaw, G., Leusch, F. D., & Knight, N. L. (2012). Chlorine disinfection by-products in wastewater effluent: Bioassay-based assessment of toxicological impact. Water Research, 46, 6069–6083. https://doi.org/10.1016/j.watres.2012.08.026. Weinberg, H. S., Krasner, S. W., Richardson, S. D., & Thruston, A. D. Jr. (2002). The occurrence of disinfection by-products (DBPs) of health concern in drinking water: Results of a nationwide DBP occurrence study. EPA/600/R-02/068. Athens, Ga.: EPA Office of Research and Development. Accessed on March 22, 2018, from https://cfpub.epa.gov/si/si_public_ record_report.cfm?dirEntryId=63413. Whitaker, H., Nieuwenhuijsen, M. J., Best, N., Fawell, J., Gowers, A., & Elliot, P. (2003). Description of trihalomethane levels in three UK water suppliers. Journal of Exposure Analysis and Environmental Epidemiology, 13, 17–23. https://doi.org/10.1038/sj.jea.7500252. Zhang, X., & Minear, R. A. (2002). Decomposition of trihaloacetic acids and formation of the corresponding trihalomethanes in drinking water. Water Research, 36, 3665–3673. https://doi. org/10.1016/S0043-1354(02)00072-6. Zhang, X., Minear, R. A., Guo, Y., Hwang, C. J., Barrett, S. E., Ikeda, K., et al. (2004). An electrospray ionization-tandem mass spectrometry method for identifying chlorinated drinking water disinfection byproducts. Water Research, 38, 3920–3930. https://doi.org/10.1016/j. watres.2004.06.022.

Chapter 9

Functional Nanoporous Titanium Dioxide for Separation Applications: Synthesis Routes and Properties to Performance Analysis Andrea Merenda, Lingxue Kong, Bo Zhu, Mikel C. Duke, Stephen R. Gray and Ludovic F. Dumée

Abstract Titanium dioxide represents an attractive industrial material for a wide range of applications, however in the last decades, research has been focused on its implementation in remediation systems for water treatment. The need to design nanoporous and nanotextured titania materials has arisen from the unique, beneficial properties of nanoscale titania for catalysis, separation and membrane sieving. This chapter reviews the synthesis procedures to generate tuneable titania materials either as self-supporting structures or as active layers on top of other porous materials. Finally, the catalytic properties of nanoporous and nanostructured TiO2 are reviewed for the degradation of organic compounds in wastewater. Significant parameters, such as specific surface area and crystallite size, are shown to be critical and must be optimised towards the fabrication of catalytic reactors for Advanced Oxidation Processes (AOP). Keywords Sol-gel deposition Advanced oxidation processes Nanoporous titania materials


Photo-induced processes
Sludge reactors
Degradation of organic compounds

A. Merenda (&)
L. Kong
L. F. Dumée (&) Institute for Frontier Materials, Deakin University, Waurn Ponds, Geelong, VIC 3216, Australia e-mail: [email protected] L. F. Dumée e-mail: [email protected] B. Zhu
M. C. Duke
S. R. Gray Institute for Sustainability and Innovation, Victoria University, PO Box 14428, Melbourne, VIC 8001, Australia © Springer International Publishing AG, part of Springer Nature 2019 M. Pannirselvam et al. (eds.), Water Scarcity and Ways to Reduce the Impact, Applied Environmental Science and Engineering for a Sustainable Future, https://doi.org/10.1007/978-3-319-75199-3_9

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Introduction

Catalytic reactors represent attractive solutions for the remediation of organic compounds that present both reluctance towards biodegradation and potential toxicity if complete oxidation is not achieved. Membrane catalytic technologies have been attracting the attention of the scientific community as novel, high efficient and cost saving systems to replace ordinary chemical or physical remediation units in treatment plants, such as mechanical pre-treatments, secondary oxidation, aerobic degradation and de-coloration. Specifically, selective removal of pollutants in wastewater can be carried out on a porous membrane filtration unit where the sieving effect is provided by the pores and the chemical affinity within the surface and the pollutant. However, a main challenge in membrane technologies is the achievement of high selectivity without losing permeate flux during the process, consequently hindering the performance. Strategies to combine high selectivity into an active layer that can also achieve the complete degradation of organic compounds have the potential to lead to costeffective advanced separation processes with high versatility and wise use of resources. Over the last decades, titanium dioxide has been captivating the attention of scientists for chemical, mechanical and photocatalytic properties opening application fields such as biocomposite materials for biomedical use (Saranya et al. 2011; Kailasanathan et al. 2012), photocatalysis (Fujishima et al. 2008; Gaya 2013; Wu et al. 2014; Alrousan et al. 2012), photovoltaic cells (Grätzel 2001; Kay and Grätzel 1996; Coakley et al. 2003), sensing (Mor et al. 2003; Varghese et al. 2003a, b) and water photoelectrolysis (Paulose et al. 2006; Varghese et al. 2005). Among the materials investigated for novel applications, titanium dioxide has emerged as an ideal candidate due to its large availability, undemanding and straightforward manufacture, and mechanical and chemical properties such as high thermal and chemical stability, low corrosion rate and high UV-light absorption. As a band gap semiconductor, titanium dioxide is the ideal material to generate electron–hole pairs to be applied in photovoltaic and photocatalytic technologies. The generation of charge carriers upon UV-light irradiation represents the key element for heterogeneous photocatalysis, where strong oxidating species are produced from active sites on the surface of a photocatalytic material. Amongst the strategic targets of such materials, the remediation of agricultural effluents containing harmful chlorinated phenol derivatives represents a key issue to reduce the environmental impact of food processing and animal husbandry activities. Persistent organic compounds and chemicals are present in wastewater and their remediation must be tackled to meet the increasing tight environmental requirements in terms of water quality and water reuse. The remediation of these compounds is typically provided by an off-site plant and performed via thermal treatment or chemical oxidation, potentially generating further harmful emissions due to the presence of halogenated reaction intermediaries. The development of

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strategies for an efficient, in situ degradation would improve the efficiency of the water remediation cycle while providing a cost-saving and more sustainable separation process. This chapter reviews recent advanced oxidative water treatments based on the synthesis and modification of nanoporous and nanotextured titanium dioxide materials. Photocatalytic processes promoted by the electron/hole separation upon UV–vis radiation and in situ generation of oxidising agents are known as Advanced Oxidation Processes (AOP), and it conceptually represents an efficient strategy to replace traditional chemical oxidation processes. This review chapter will cover the synthesis routes to fabricate nanoporous titanium dioxide in different forms and shapes and propose a critical analysis of their strengths and weaknesses as efficient catalytic materials. Each section will then address the properties responsible for the material’s morphology and microstructure and eventually highlight the potential of specific nanoporous materials for advanced water purification technologies.

9.2

Titanium Dioxide Synthesis Routes and Subsequent Properties

Among all the possible applications, titanium dioxide has been mostly used as a reinforcement agent due to its mechanical strength, thermal stability, chemical inertness even in aqueous environments and the ability to combine with other ceramic or metal materials to form ceramic and organic composite materials (Sakka et al. 2014; Khaled et al. 2010). The unique biocompatibility of titanium dioxide, according to the high stability of the oxide surface in biological environments, has also drawn attention towards its incorporation in biocomposite materials for medical implants based on polymers (Santos et al. 2007). Nanoscale titanium dioxide is now one of the most widely used nanomaterials, not only for applications involving its n-type semiconductor nature such as photovoltaics and photocatalysis, but also because of its long electron life time, suitable for a long period of photocatalytic activity requirements, corrosion stability and low cost. Titanium dioxide can be produced in several forms such as porous layers, nanoparticles, sheets or fibres and nanotubes (TNTs) (Chen and Mao 2007). Depending on the specific application, titanium dioxide’s performance is influenced by its nanoscale properties stemming from its morphology and the microstructure. As size, shape and crystal structure vary, properties such as surface area, crystallite size, porosity and electric charge transfer change consequently, therefore requiring the choice of a suitable fabrication route in a bottom-up or top-down approach to optimise them accordingly. The control of titanium dioxide phase structures and phase transitions have been investigated since physical and chemical properties, such as photocatalytic activity, may vary in accordance with the crystalline structure (Yu et al. 2011; Zhang et al. 2008, 2014). Titanium dioxide can be found in nature in four different forms, each having a different lattice structure. Anatase and

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rutile present tetragonal arrangement, while brookite is orthorhombic and titanium dioxide (B) is monoclinic (Carp et al. 2004). The two most studied forms are rutile and anatase, both consisting of titanium dioxide (Alrousan et al. 2012) octahedral crystal structures, as the others forms of titanium dioxide are unstable and require specific synthesis routes (Sorantin and Schwarz 1992). The disposition of the rutile and anatase octahedral structures differs and results in variations to their electronic properties, with anatase being the stronger photocatalyst. In rutile, the octahedral lattice structure shares corners with eight neighbours and edges with two other neighbours, while in anatase each octahedron lattice shares corners with four other octahedral lattices and edges with another four, forming a zig-zag chain while rutile has linear chains (Diebold 2003). Furthermore, rutile is the most stable phase at every temperature and at pressures below 60 kPa, while anatase is more stable at particle sizes less than 11 nm (Zhang and Banfield 2000). Considering these characteristics, the crystallinity of the titanium dioxide must be carefully controlled and the transition within the two phases encouraged or blocked depending on the desired properties.

9.3

Nanoporous Titanium Dioxide Fabrication Routes

Titanium dioxide can be prepared into different forms and shapes. Powders, rods, wires and films usually require a bottom-up approach, which involves chemical reactions in liquid or gaseous media (Xu 2013). The advantages of these synthesis routes are related to the good stoichiometric control of reactants and the possibility of creating coatings of different shapes and morphological characteristics such as porosity, pore size and pore density. However, synthesis in solution typically requires expensive precursors, long treatment times and may retain impurities such as polymeric precursors (Carp et al. 2004). Gas phase pathways, however, have been successfully applied to thin film deposition and coatings, and do not necessarily involve chemical reactions between precursors, as in the case of Sputtering (SP) (Banerjee 2011). The techniques presented offer alternatives for synthetising titanium dioxide with different morphological and microstructural characteristics, as in almost each case properties such as surface area, pore size, crystallite size and crystallinity are directly derived from the fabrication approach and operating parameters. In this section, a comparison showcasing advantages and drawbacks of the various synthesis strategies will be presented, as well as insights into the morphological characteristics of nanoporous titanium dioxide achievable by the most studied synthesis routes. The role of the crystallinity, surface area, porosity and pore size distribution will be evaluated focusing on suitability for filtration systems. Lastly, a correlation between surface area, crystallite size distribution and reactivity and properties of such materials will be related to their catalytic properties.

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Sol-Gel Deposition

The sol-gel process is usually applied to ceramics to deposit films of particles. This method involves the formation of a sol by the hydrolysis and polymerisation of precursors. The sol is then turned into a solid gel phase by complete polymerisation and loss of solvent by heat treatment and drying (Schwarz et al. 1995; Pierre and Pajonk 2002). The usual sol-gel synthesis routes for porous titanium processing can be divided into two main categories depending on the type of precursor used, non-alkoxide or alkoxide, respectively (Sivakumar et al. 2002; Watson et al. 2004). Non-alkoxide precursors such as nitrates and chlorides have been investigated because of their low cost when compared to the alkoxides, however the removal of the halides from the final product has to be tackled and therefore the alkoxide route remains the most widely studied (Srivastava 2014). The key to efficiently control the reaction and to obtaining the desirable results is in the separation between the hydrolysis step and the condensation process (Livage et al. 1988). In order to better separate the two steps, acid–base catalysis is usually included and complexation agents, consisting of carboxylates, may be required. Subsequently, these reactions must be followed by a thermal treatment, such as calcination, to eliminate the organic impurities and control the microstructure in terms of crystallinity and crystallite size of the final product (Yang et al. 2006). Sol-gel synthesis has been successfully applied to obtain a wide range of titanium dioxide materials, such as powders, nanorods, nanowires or films, as shown in Fig. 9.1a. The main advantage is that the process can be tuned by control of the stoichiometry and the reaction conditions, enabling high flexibility, purity, homogeneity and the possibility of coating different substrates (Carp et al. 2004). Although the pore size can be controlled by the addition of surfactants acting as templates (Galkina et al. 2011) to obtain a specific narrow pore size of a few nm in the range of 5–10 nm (Patil et al. 2015; Yu et al. 2002), the specific surface area remains a critical drawback as it is more than halved upon calcination (Patil et al. 2015). After thermal treatment at 500 °C, a partial coalescence of crystallites from 12 to 16 nm and an increase in pore size from 14 to 23 nm (Chen et al. 2009) have been registered for a porous TiO2 layer deposited onto a pre-formed alumina membrane. The application across processes requiring high specific surface area, such as heterogeneous photocatalysis, is therefore hindered by the potential loss of active sites on the surface where the photocatalytic reaction takes place. In membrane filtration, the pore size is critical to optimise selectivity and permeability, therefore a lack of control over this parameter can generate undesirable loss in selectivity (Kanani et al. 2010; Mehta and Zydney 2005) and alter the membrane performance.

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Fig. 9.1 Titanium dioxide morphology formed by different synthesis strategies. a Sol-gel (Rawolle et al. 2012), b hydrothermal synthesis (Jimmy 2006), c electrodeposition (Miao et al. 2002) d CVD (Wu and Yu 2004), e ALD (Tupala et al. 2012), f sputtering (Sanchez et al. 2012), g direct oxidation (Peng and Chen 2004), h anodised titanium dioxide (Permission for reproduction granted)

9.3.2

Hydrothermal and Solvothermal Synthesis

Hydrothermal and solvothermal synthesis includes fabrication routes whereby chemical reactions in aqueous or organic media induce the deposition of titanium dioxide under self-produced pressures at low temperatures (below 250 °C) and controlled pressures. The specific surface area can be dramatically altered by slight increases in temperature from 200 to 240 °C, or variation of the precursor concentration or the water content, generating a steep drop from 190 to 10 m2/g. The loss in surface area has been correlated to the coalescence of nanoparticles into bigger clusters,

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from 10–14 nm to 180 nm (Yang et al. 2000; Chae et al. 2003). The treatment duration can significantly impact the morphologies and a decrease in surface area up to 30%, from 260 to 192 m2/g, was obtained upon increasing the treatment duration from 1 to 5 h (Yu et al. 2007). Longer treatment durations also produce a slight loss in porosity, from 62 to 57%, along with an increase in pore size and crystallite size as shown by increasing the treatment temperature from 100 to 200 °C at fixed conditions (Yu et al. 2007). This result is due to the rearrangement of the structure with the coalescence of smaller particles and the phase transition from amorphous to anatase. The pore size is usually distributed as bimodal as demonstrated in the previous studies (Kumar et al. 1994) due to the primary particle agglomeration upon heat treatment generated by the crystalline change. The smaller pores are usually distributed in the range of 4–8 nm while larger pores of 40 nm are also formed upon heat treatment (Yu et al. 2007). The porosity can also be controlled by tuning the form of the deposited particles, as titanium dioxide can be produced as nanoparticles, represented in Fig. 9.1b, nanorods, nanowires and nanotubes (Yu et al. 2007; Kitano et al. 2007; Kasuga et al. 1998). Particle size or pore size distributions and preferential facets can be varied by replacing the aqueous media with an organic media, and by adding surfactants (Kim et al. 2003). In case of solvothermal synthesis, narrower distributions of pore size in the range of 5–6 nm are observed in organic solvents as ethanol, although the distribution remains bi-modal (Ma et al. 2012). The use of different organic solvents, such as acetone and methyl ethyl ketone, can lead to a significant variation of pore size from 18.2 to 5.5 nm at fixed conditions for the deposition of nanotubes, respectively, while the crystallite of nanoparticles can be reduced to 10 nm with specific surface area up to 200 m2/g (Nam et al. 2013). The hydrothermal method typically requires a final heat treatment to obtain the desired morphology upon the deposition of thin films, therefore potentially generating partial aggregation and bigger pores other than the original small size. Furthermore, these processes are typically time-consuming since the optimisation of microstructural parameters is due to slower reaction rates, requiring even 24 h of autoclave permanence (Im et al. 2012).

9.3.3

Electrodeposition

Electrodeposition is bottom-up approach used to form nanotextured titania materials by reducing a titanium dioxide precursor across a porous substrate, with the substrate acting as both a template and a cathode. The deposition requires control of process parameters such as pH, temperature, applied voltage and current density, as well as the concentration of Ti precursors (Carp et al. 2004; Liu et al. 2004). The dependence of the crystallite size on the concentration of Ti precursor has been reported, with lower crystallite detected at lower temperature (Fustes et al. 2008). This method can be used to fabricate titanium dioxide nanowires of specific pore distributions within a substrate, provided by the alumina template which, in the case

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of anodised alumina nanotubes, can be reduced to 5 nm. The fabrication of nanowires across 50-nm diameter pore size alumina templates, shown in Fig. 9.1c, led to the formation of pure anatase phase exhibiting a crystallite size distribution around 7 nm after annealing (Miao et al. 2002). Nonetheless, the interface within the template and the deposited metal can represent a limitation, requiring a surface modification strategy for the substrate and its removal upon electrodeposition. Furthermore, a thermal post-treatment must be conducted either to remove the template and/or to obtain the desired crystallinity. The significant advantage of this technique over the other fabrication routes is that it does not include any organic ligand, stabiliser or complexing agent, thereby resulting in a purer product with a specific crystalline phase (Liu and Huang 2005).

9.3.4

Chemical Vapour Deposition

Chemical Vapour Deposition (CVD) represents a versatile fabrication route to deposit or coat substrates of different shapes and size with high-purity titanium dioxide. In a common synthesis, a titanium dioxide precursor is vaporised into a vacuum chamber where the targeted substrate is placed. The process then involves homogeneous reactions between precursors which take place in the gas phase, followed by subsequent heterogeneous reactions that generate titania film across the targeted substrate (Goossens et al. 1998). The process can be finely controlled to coat different materials and often obtains good adhesion between the deposited titanium dioxide and the substrate as shown in Fig. 9.1d, while morphological parameters of the film can be controlled through by selection of the operating conditions during synthesis. The high versatility of this technique lies in the possibility of further improving the system in terms of reducing the T and p requirements as well as preferentially controlling either the homogeneous reactions or the heterogeneous one, resulting in powder deposit or film growth, respectively. The importance of temperature was investigated in depth, showing that grain size in the film is strongly dependant on this parameter. In particular, raising the chamber temperature results in bigger crystallites, as they increased from 48 to 133 nm while the particle created during the homogeneous reaction increased from 8 to 20 nm (Seifried et al. 2000). Interestingly, anatase was stable up to 900 °C when normally during sintering the titanium oxide would turn into rutile, and higher temperature generated a porous structure since the film consisted of nanoparticles (Goossens et al. 1998). The use of an organometallic precursor may also allow for milder chamber conditions (MO-CVD) and a decrease of the temperature to as low as 220 °C, while pure anatase would be formed at 600 °C heated substrate. Increasing the O2 flow rate led to a reduction of the particle size, from 23 to 12 nm with an increase in specific surface area from 65 to 125 m2/g (Li et al. 2004). The precursors can also be introduced in a plasma state, to enhance the reaction rate (PA-CVD) or alter the geometry of the deposition when coupled with spray or electrospray systems (SA-CVD or EA-CVD).

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The possibility of controlling film growth and particle deposition makes this technique particularly interesting to tune the transition from a dense to a porous layer. The high surface area achievable as well as low defect production (Jung 2008) represent attracting outcomes for further development of this technique, although the porous structure is usually determined by the substrate on which it is deposited (Jung 2008; Ding et al. 2000).

9.3.5

Atomic Layer Deposition (ALD)

ALD is a novel technique to control film thickness deposition rates and achieved highly uniform surfaces and coatings. It also allows for the in situ design of nanostructures, at low growth temperatures (Leskelä and Ritala 2002; Sneh et al. 2002). The deposition of titanium dioxide upon ALD has been investigated starting from TiCl4 as a convenient precursor (Matero et al. 2001). However, the corrosive nature of this chemical and the HCl produced as a by-product represent undesirable problems. Different Ti precursors have been studied including organometallic compounds, which provides a solution that avoids these problems. Amide-based or Ti alkoxides are used, such as titanium tetraisopropoxide (TTIP) (Reiners et al. 2013; Linsebigler et al. 1995). The decomposition of the Ti precursor is essential to control the crystallinity of the deposited layer (Cheng et al. 2009). With TiCl4 as precursor, the deposited film was found to be amorphous below 150 °C, while above 200 °C complete crystallisation into anatase was observed. Anatase remained the crystalline form until 300 °C, when it started to turn into rutile (Matero et al. 2001). In the case of TTIP, the deposition of anatase was optimised by applying different temperatures during the nucleation and the growth processes, 60 and 220 °C, respectively, while a non-uniform anatase film was deposited when the T was fixed at 220 °C (Guerra-Nunez et al. 2015). Nonetheless, the use of an amino-Ti precursor with narrow temperature decomposition window, as well as ozone instead of water was found to introduce high-purity anatase crystals at 250 °C while rutile was formed above 350 °C and pure rutile observed at 350 °C (Jin et al. 2015). Temperature also has a significant role in supporting either the growth or the nucleation of anatase crystals: crystallite growth was found to be favoured at low T such as 200 °C with crystallite size of 65 nm, while increasing T up to 300 °C resulted in faster nucleation and smaller crystals with nominal size of 45 nm (Aarik et al. 2001). The flexibility of this technique relies on the possibility of coating substrates of different shapes, or use sacrificial supports to obtain titanium dioxide with high specific surface area for photocatalytic application. Anodised alumina nanotubes can be coated with titanium dioxide as in Fig. 9.1e using ALD process (Kemell et al. 2007). Other suitable substrates are glass (Tan et al. 2010), carbon nanotubes (Verbruggen et al. 2014) or sponge-structured commercial substrates to act as a template (Shengqiang et al. 2015). The variety of potential templates that can be introduced paves the way for highly tuneable surface

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and bulk properties such as porosity, pore size distribution and specific surface area while a narrow decomposition T of the precursor is responsible for film uniformity and crystalline phase.

9.3.6

Sputtering

Sputtering is a technique often used to deposit thin films or coatings on a substrate or a template, by applying an electric field. Depending on the drive-force, the sputtering is usually divided into Direct Current (DC) or Radio Frequency (RF). However, while RF sputtering can be adapted to every target, the DC method works only on electrically conductive materials (Rodríguez et al. 2000). RF sputtering is usually supported by a magnetron so that the plasma atmosphere, which evaporates the native target and guides the deposition onto the substrate, can be confined close to the surface (Sima et al. 2007). The morphology of the titanium dioxide phase was found to be correlated with the sputtering conditions and the plasma atmosphere, consequently the technique allows good control over these parameters (Dannenberg and Greene 2000). The crystallinity of the deposited layer can be affected by various factors, such as the bias applied, the nature of the gas carrier and the partial O2 pressure. A significant increase in rutile content was found when the voltage was increased from 10 V, with pure anatase present, up to 80 V when the crystalline transition is completed. At fixed pressure, the content of rutile is linearly dependent on the voltage and almost 50% anatase is converted into rutile at 30 V. This variation of crystalline phase with voltage was also found to be related to the total sputtering pressure (pT). At higher pT, the transition becomes less favourable as shown by only 10% of titanium oxide being in the rutile phase at 30 V (Song et al. 2006). Studies have confirmed that the crystal structure of such films is strongly affected by the kinetic energy of particles bombarding the substrate, which therefore opens the route of tuning the crystal lattice of the surface grains (Song et al. 2006; Okimura et al. 1996). The increase in O2 partial pressure, pO2, was also found to lead to a transition from amorphous, at 0.075 Pa to rutile and finally anatase at 0.2 Pa, with fixed pT and substrate T at 160 °C (Šícha et al. 2007). Interestingly, similar results were obtained in another study (Musil et al. 2006) where pure anatase crystals were observed at high pO2 with fixed pt. Furthermore, it was confirmed that lower deposition rates lead preferentially to anatase phase, while at higher rates rutile starts appearing. At deposition rates, such as 9 nm min−1 only anatase is deposited while at 50 nm min−1 pure rutile is obtained. The outcomes presented showcase two advantages of this technique, as high deposition rate and high purity can be obtained by controlling the process conditions. The deposition of a pure titanium dioxide phase is also desirable since it generates lower Ra, as 6 nm for pure rutile or 8 nm for pure anatase, while in presence of a mixture it is increased by a factor of 3 (Šícha et al. 2007). However, the very low porosity of the as-deposited film undermines direct application as a porous substrate, although the possibility of tilting the support during the process

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enables the fabrication of porous layers with a porosity up to 25 and 33% for tilt angles of 30° and 70° respectively (Ren et al. 2010). The high deposition rate and high purity can, however, be significant to the deposition of thin films for a further chemical or electrochemical morphological modification (Chappanda et al. 2015) or to deposit a high-purity titanium dioxide layer over a porous template as anodic alumina (Sanchez et al. 2012) shown in Fig. 9.1f.

9.3.7

Direct Oxidation

Direct oxidation of titanium foils represents a top-down approach to produce nanosized titanium dioxide materials. The synthesis takes place under controlled solutions where the oxidising agent is typically represented either by oxygen peroxide or acetone. The process can take place at T as low as 80 °C in the presence of H2O2 (Wu 2004), while high T of 850 °C is required when acetone is used. The use of acetone, however, was found to be beneficial to the deposition of well-aligned titanium dioxide nanorod arrays as shown in Fig. 9.1g, while the use of a gas feed such as Ar/O2 or pure O2 gas led to polycrystalline films and oriented-grown nanofibers, respectively (Peng and Chen 2004). The nanorods formed pure rutile phase and the crystallite size was time-dependant with an increase in crystallite size over the treatment time. Nonetheless, the long exposure to the oxidising solution in the case of H2O2, up to 72 h, as well as the high process temperature required for acetone, do not make this strategy attractive in terms of energy required and the lack of control over the deposition rate, particle shape and crystallinity represent a significant drawback when compared to other deposition techniques such as sol-gel or hydrothermal processes. However, to date, very limited details about the morphology of the pores and the surface area have been provided, limiting the possibility of drawing comparisons with anodisation, the other top-down approach presented.

9.3.8

Anodisation

The electrochemical anodisation method is regarded as one of the relatively simple techniques to synthesise titanium dioxide nanotubes with large surface area, narrow pore size distribution and thickness of a few dozens of nm to several hundred of lm (Fig. 9.1h) (Prakasam et al. 2007). The one-dimensional and highly ordered nanotube architecture offers an excellent electrical channel for charge transfer resulting in an effective separation of electron–hole pairs with enhanced photoelectrochemical performance (Lee and Schmuki 2015). A significant advantage of this synthesis route is the precise control over the morphological parameters that can be obtained by controlling the process conditions. The impact of synthesis parameters such as applied voltage, electrolyte composition, solvent, duration time and temperature has

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been deeply described, although some key aspects such as the growth mechanism and the lack of crystallisation are still being debated. The possibility of creating iso-porous arrays of nanotubes with straight pores in the range of 12–350 nm represents an interesting advantage in many applications. For instance membrane filtration, where control over the pore size and pore size distribution is critical to optimise membrane selectivity and permeability (Mehta and Zydney 2005).

9.3.9

Comparison of Fabrication Routes Towards Nanoporous Titanium Dioxide

The techniques presented reveal that the microstructural and morphological parameters can be tuned to generate nanoporous titania materials with pore size and surface area ranging between 4 and 300 nm (Yu et al. 2002), and 8 m2/g to over 1000 m2/g (Grimes 2007), respectively. To form high-purity titanium dioxide, CVD or ALD may not be recommended because of the contamination with halogenated precursors, while on the other hand, electrodeposition or sputtering offer extremely viable solutions with purities above 99.9%. The high specific surface area is a critical parameter for heterogeneous applications of titanium dioxide (Shan et al. 2010). The porosity as well as the distribution of the pores may be tuned in the range of 4–5 nm in sol-gel routes up to hundreds of nm in anodisation. Table 9.1 summarises the principal aspects that emerge for each technique in terms of advantages and drawbacks. Depending on the specific application, different routes can be followed to obtain the most suitable combination of morphological parameters. In membrane ultrafiltration, the possibility of creating straight iso-porous channels provided by anodisation is attractive to obtain high selectivity towards specific compounds while having low tortuosity within the tubes. The high specific surface area, furthermore, represents an attractive characteristic for chemical reactions mediated by this substrate, such as in heterogeneous photocatalysis. The morphological properties of anodised titanium dioxide will be therefore presented, showcasing the key parameters to control the pore size and the tube length and the strategies to overcome the limitations that emerge from the tube growth mechanism such as lack of crystallinity and low mechanical resistance.

9.4

Titanium Dioxide Applied to Photo-Induced Processes

Light activation of titanium dioxide for implementation of photo-induced processes has been developed since the early 1960s. In 1972 (Fujishima and Honda 1972), the use of titanium dioxide as a photo-anode in an electrochemical cell for water splitting was first reported. Although the improvement of photocatalytic water

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Table 9.1 Comparison of different titanium dioxide nanoporous synthesis routes Technique

Morphological properties

Drawbacks

Sol-gel

Narrow pore size, 5–20 nm Surface area up to 100–150 m2/g Possible introduction of foreign dopants Deposition of titanium dioxide on different forms and shapes Use of templates, therefore assuming its characteristics, high purity Deposition of thin layers with good adhesion Tuneable morphology

Introduction of organic impurities Loss of surface area upon thermal treatment to tune crystallinity

Hydrothermal Electrodeposition CVD

ALD

Deposition on templates or sacrificial substrates Deposition on substrates of different shape and form

Sputtering

Uniform film with good adhesion, high purity Only T and pT control required Top-down approach easy set-up

Direct oxidation Anodisation

Creating nanotubes with enhanced specific surface area >1000 m2/g, self-ordered, tube diameter controlled up to 10–20 nm, iso-porosity

Requires autoclave and heat source Bi-modal distribution of pores Uniform films but lack of porosity Requires high T and UHV along with a reactor Fine optimisation of kinetics and mass transport Presence of contaminants and requires fine control over treatment conditions. Choice of the precursor, study of the reaction kinetics and mechanism Slow rates required to preferentially deposit anatase No porosity with standard treatment High T up to 850 °C or long treatment times up to 72 h Anodised array can be easily detached from the substrate Lack of knowledge in the mechanism, film amorphous

splitting and solar cell technology has been extensively studied with titanium dioxide substrates, the possibility of carrying out oxidative mineralisation of organic pollutants was more recently investigated. In 1983, semiconductor-sensitised reactions (Pruden and Ollis 1983), whereby a suspension of titanium dioxide that was activated under UV light resulted in the complete mineralisation of chloroform in aqueous solution. The early studies on the application of titanium dioxide in heterogeneous photocatalysis (Fox and Dulay 1993) promoted a new wave of research on both the selective mineralisation of organic compounds to specifically target a component present in an effluent, or the unselective oxidation of organic molecules for water and air purification purposes (Ollis and Al-Ekabi 1993; Mills et al. 1993). When activated under UV light, titanium dioxide has been proven to be an efficient photocatalytic material to degrade a large variety of organic compounds, spanning from alkanes, carboxylic acids, aromatics, haloaromatics, pesticides and dyes (Fujishima et al. 2008). Consequently, titanium dioxide has captivated the attention of scientists as a valuable candidate in heterogeneous photocatalysis for the removal of contaminants in wastewater.

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The increasingly demanding standards related to water purity and to the remediation of industrial and agrochemical waste effluents require new and more efficient strategies to meet discharge concentration thresholds. The key factors for the realisation of breakthrough remediation systems are the overall process efficiency, its environmental sustainability and the possibility of cutting costs and saving energy. Furthermore, it is highly desirable that the degradation could lead to the complete mineralisation of the targeted compounds without generating harmful or more toxic intermediaries (Garoma and Gurol 2004; Lazarova and Bahri 2004). In this section, the main remediation routes for organic compounds will be discussed and novel strategies for more efficient separation systems based on titanium dioxide will be reviewed. In this scenario, traditional treatment technologies, such as air stripping and chemical oxidation, are nowadays considered inefficient. Granular Activated Carbon (GAC) has been considered and used even though the adsorption energy, recyclability and selectivity of these materials are relatively limited. Alternative biological treatments have also been studied and set-up in several treatment plants, consisting of activated sludge processes or bioreactors. However, drawbacks such as the slow reaction rate and the need for tight control over pH and T can limit its suitability for application, especially towards the most resilient organic compounds, such as most of the aromatics.

9.5

Titanium Dioxide-Based Technologies

Titanium dioxide has been implemented in water treatment systems since the development of heterogeneous photocatalysis as an efficient route to replace traditional remediation processes. The combination of nanotechnologies and photocatalysis has been aiming at novel, sustainable and more efficient remediation processes. The promising results led to the development of a class of treatments defined as Advanced Oxidation Processes (AOP) where the semiconductor provides the reaction sites and the oxidative agents.

9.5.1

Advanced Oxidation Processes (AOP)

Advanced Oxidation Processes (AOP) represents a new class of treatments known to provide better performance in terms of pollutants degradation, if compared to the traditional techniques of coagulation/flocculation or adsorption on different adsorbents such as activated carbon and silica gel (Comninellis et al. 2008; Azbar et al. 2004). The in situ generation of active oxidative species such as OH, O2−, H2O2 allows for the complete mineralisation of recalcitrant organic compounds which are hardly removed with traditional techniques (Ameta et al. 2013; Esplugas et al. 2002). Consequently, the formation of intermediaries or by-products is avoided or

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reduced whilst presenting advantages such as high reaction rates, lower energy consumption than thermal destruction processes such as incineration and the possibility of combining with other pre- or post-treatments (Loures et al. 2013; Arredondo Valdez et al. 2012). Typically, AOP treatments are divided into homogeneous and heterogeneous pathways depending on the reaction phases, while the main oxidative agents are ozone, H2O2, UV light, Fenton reactants and photocatalytic materials in heterogeneous AOPs. The latter have captivated attention because of their versatility and the possibility of reducing energy consumption associated with ozone generation. Titanium dioxide is low cost, non-toxic, highly stable over a wide range of pH and insoluble in water, which enables convenient separation from aqueous media and the possibility of immobilising it on different supports such as glass, silica, polymeric materials and GAC (Shan et al. 2010). Titanium dioxide has, therefore, been successfully implemented in the treatment of hazardous organic pollutants in wastewater following two different engineering pathways: as dispersed particles or immobilised on substrates or fixed beds.

9.5.2

Sludge Reactors

Titanium dioxide photocatalytic activity is usually exploited in slurry reactors where a source of UV radiation is provided and the active material is finely suspended to provide higher specific photocatalytic surface to the feed. However, fine titanium dioxide particles present a further problem related to the recovery of the catalytic substrate. The post-treatment removal of titanium dioxide, requiring filtration and subsequent resuspension can represent an undesirable cost in terms of dedicated devices and time (Mahmoodi and Arami 2006). Moreover, the UV-light exposure of titanium dioxide suspended powders can be undermined by other molecules, for example, dyes, present in the reactor, reduce the depth of penetration of the radiation. Nonetheless, it has been reported that the particles, given their high surface energy, have the tendency to agglomerate thus reducing the active surface area and the overall treatment efficiency (Li et al. 2010). Although the formation of titanium dioxide clusters can be reduced by carrying out surface modification (Monllor-Satoca et al. 2011; Bizarro et al. 2009; Zou et al. 2010) or by controlling the pH of the reactive media (Li et al. 2010; Hasan Nia et al. 2015), the photocatalytic activity is still dependant on factors other than the form of the photocatalytic material, and post-treatment filtration and recovery cannot be dismissed (Balázs et al. 2008). Consequently, the immobilisation on fixed beds or other substrates can tackle both the issues, even though it may result in a loss in photocatalytic surface compared to the dispersed system (Choi et al. 2007).

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Immobilisation on Supports

An efficient support should provide good adherence, high specific surface area, strong adsorption affinity towards the pollutants and should not induce any significant modification in the catalyst activity during the synthesis (Shan et al. 2010). The adhesion of titanium dioxide onto a support can provide better engineering control over the optimal exposure to the activating radiation as UV or visible light (Bideau et al. 1995). Supports are commonly divided into two main categories, transparent materials and opaque substrates. The former includes glass, as tubes, rings, beads or plates (Ryu et al. 2003; Khalilian et al. 2015), and silica (Anderson and Bard 1997; Wong et al. 2011), whilst the latter has activated carbon (Shi et al. 2008), metals and alloys such as stainless steel (Mozia et al. 2012), ceramic as alumina (Anderson and Bard 1997) and polymers such as polystyrene or polyethylene beads (Fabiyi and Skelton 2000). The immobilisation of titanium dioxide onto substrates opens, therefore, the way to application in membrane science, considering the development of meso and nanoporous coatings in the range of Micro Filtration (MF) and Ultra Filtration (UF) (Jing et al. 2009; Bosc et al. 2005).

9.5.4

Titanium Dioxide as Photocatalytic Materials Applied in Membrane Science

First applications of titanium dioxide involved the treatment of specific VOCs in gas phase, such as trichloroethylene (Maira et al. 2003), methanol (Tsuru et al. 2006) or formaldehyde (Peterson et al. 1994; Noguchi et al. 1998), whereby the pollutants can be directly oxidised to CO2 at room temperature without requiring a further condensation step (Koren and Bisesi 2002). The method has been applied to water treatment as an AOP technology arranged as a Photocatalytic Membrane Reactor (PMR) (Dionysiou et al. 2016). At first, the photocatalytic agent was not integrated into the membrane unit. The filtration module was either incorporated into a slurry reactor, where the photocatalysis process was carried out by titanium dioxide particles, or it was placed as a self-standing unit following the photocatalytic reactor (Cheng et al. 1995; Kumar et al. 1993). In recent years (Bosc et al. 2005), the possibility of coupling directly the photocatalytic activity and the filtration has captivated the attention of researchers in order to avoid the drawbacks given by the titanium dioxide suspended powders and their recovery. Different synthesis procedures, described in subsequent paragraphs, have been carried out to control and optimise the main membrane characteristics as porosity, specific surface area, pore size and pore size distribution. When considering the dispersion or the addition of titanium dioxide nanoparticles onto a porous substrate, usually polymers and ceramics are considered ideal candidates for the supporting membrane. Titanium dioxide can be either immobilised as nanoparticles or dispersed in the polymer solution for membrane casting.

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Typical substrates include polyamide (Kim et al. 2003), polyurethane (PU) (Liu et al. 2012), polyethylene terephthalate (PET) (Jianguo 2015), polyester (Barni et al. 1995), polyacrylonitrile (PAN) (Kleine et al. 2002) and polytetrafluoroethylene (PTFE) (Yamashita et al. 2003). In the case of dispersion onto a pre-formed membrane, typical routes require either reaction of Ti4+ with surface carboxylic groups or hydrogen bonds within carbonyl groups and surface hydroxyl groups on titanium dioxide (Kim et al. 2003). Nevertheless, the detachment of titanium dioxide nanoparticles due to exposure to high pressure or high temperature represents a critical drawback, and different strategies can be followed to strengthen the adhesion within the two layers especially when weak hydrogen bonds are involved, as occur following plasma surface modification (You et al. 2012). Moreover, the stability under UV radiation remains a concern and requires further optimisation since long time-exposure up to 12 h may generate degradation for polymeric membranes (Song et al. 2012). Furthermore, it was reported that the dispersion of nanoparticles must be carefully tuned not to clog the pores and thus reduce permeate flux (You et al. 2012). However, the presence of titanium dioxide particles on the surface was shown to dramatically increase the hydrophilicity thus the wettability (You et al. 2012; Madaeni and Ghaemi 2007), which is beneficial in aqueous media to reduce fouling as proven in many studies (Teli et al. 2013; You and Wu 2013). However, the particle detachment represents an issue for these systems since it can undermine the photocatalytic efficiency. Therefore, the direct incorporation of titanium dioxide into the polymeric matrix has been considered and has led to titanium dioxide-polymer blended membranes. Typically, the membrane fabrication requires the direct dispersion of titanium dioxide nanoparticles into the casting solution (Rahimpour et al. 2011). Depending on the titanium dioxide concentration and agglomeration into the structure (Tahiri Alaoui et al. 2009; Damodar et al. 2009), this synthesis method can negatively affect the porosity while surface hydrophilicity remains unaltered (Damodar et al. 2009). Interestingly, a comparative studied was performed on titanium dioxide cast and blended membranes (Rahimpour et al. 2008). This study demonstrated that the surface coating could provide better long-term flux stability due to a more efficient antifouling characteristic, although in this case the titanium dioxide blended membrane had a more porous structure. However, polymeric membranes cannot be implemented in the treatment of those effluents requiring high thermal and chemical stability. For this reason, support materials providing high physical and chemical resistance are desirable, such as ceramics or metals. Moreover, inorganic materials can outperform polymers not only in terms of chemical inertness and thermal resistance, but they can also be used in more severe environments where stability over a large pH range, biological degradation and mechanical robustness are required, as in the food, pharmaceutical and petrochemical industries (Saleh and Gupta 2016). Nevertheless, the deposition technique to cast titanium dioxide across a ceramic support is critical to control and optimise the film or particle adhesion, the porosity,

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the thickness and the titanium dioxide phase present on the structure (Hu et al. 2011). The combination of sol-gel method and dip-coating represents a low cost, robust and mature pathway to coat alumina directly with mesoporous titanium dioxide with nanocrystallinity (Choi et al. 2006). In this case, the adhesion of titanium dioxide is improved by the generation of oxygen bridges formed during heat treatment such as calcination. However, the thermal treatment technique must be carefully chosen in order to prevent sintering, with a consequent loss of specific surface area, and avoid the transformation of anatase into rutile that would reduce the photocatalytic efficiency (Kim et al. 2002). The sol preparation and dip-coating strategy can be further improved by adding surfactants as Tween 80 in Acetone (Choi et al. 2006) or polyoxyethylenesorbitan monooleate (Choi et al. 2006) as a pore templating material, to achieve enhanced control over specific surface area, porosity, crystallite size and phase. The loading of other ceramics such as 20–33% of silica nanoparticles in the sol precursor was found to be beneficial to prevent the phase transformation of anatase during the calcination on ZrO2 supports (Zhang et al. 2006). In order to provide better control over the physical characteristics of the titanium dioxide layer and its adhesion, other methods have been recently developed such as Chemical Vapour Deposition (CVD) on ceramic supports (Ding et al. 2001). This technique has proven to achieve a uniform dispersion of the titanium dioxide layer, with improved control over the thickness and the porosity when compared to dip-coating (Athanasekou et al. 2012; Romanos et al. 2012). However, decreased permeate flux across the membrane remains a matter of concern for CVD, as well as other coating methods, even though better control over the top-layer thickness and photocatalytic efficiency in removing any pollutant residues is achieved (Alem et al. 2009; Ma et al. 2009). Recently, Atomic Layer Deposition (ALD) has been considered as valuable technique to coat titanium dioxide layers on alumina or other ceramics, with controlled thickness and porosity. Significant improvements can also be achieved with this technique in terms of obtaining a specific pore size with a narrow distribution (Narayan et al. 2009). Furthermore, this technique has provided outstanding outcomes when modifying the surface of tubular alumina, even in the form of anodic aluminium oxide (AAO), by depositing a surface layer while maintaining the integrity of the inner pores (Petrochenko et al. 2015) or reducing the pore size in a controlled manner (Cameron et al. 2000). However, even though ultra-thin films of a few nm can be deposited, the thermal stability represents an issue although a correlation within thickness and heat-induced degradation has not been reported yet (Xiong et al. 2005). Considering that only a few studies have been reported on the performance of this technique for the deposition of titanium dioxide, and the variety of precursors and further supporting treatment that can be incorporated as Plasma Assisted ALD (PA-ALD) (Rai and Agarwal 2009), this strategy represents a promising alternative to the traditional coating methods towards the deposition of highly controlled titanium dioxide porous layers on different substrates.

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169

Degradation of Organic Compounds

The investigation of photocatalytic processes on titanium dioxide substrates has led to its application for oxidation of a wide range of organic compounds, from alkanes and alkenes to carboxylic acids, benzene and derivatives, amines, pesticides and even bacteria (Ameta et al. 2012). In some cases, the remediation system is applied to address specific industrial needs when mineralisation routes without the synthesis of by-products are desired. Formic acid, for instance, can be completely mineralised without intermediary steps and by-products in 2 min with a simple heat treatment at 100 °C, which is thought to activate the less reactive sites on titanium dioxide (Muggli and Backes 2002). Oxalic acid, a sacrificial agent which promotes the photocatalytic removal of Hg or for the generation of H2 from organic molecules (Dey 2012), can be carried out on titanium dioxide without any heat treatment. In this case, the addition of Ag nanoparticles enhanced the efficiency by a factor of 5 if compared to the bare titanium dioxide due to the better charge separation provided (Szabó-Bárdos et al. 2003; Iliev et al. 2006). The degradation of fumaric and maleic acids, which are found in waste effluents in catalytic oxidation of aromatic compounds (Brackin et al. 1996), can be obtained at good yield with a good control over side reactions and adsorption on titanium dioxide depending on the pH conditions and the point of zero potential of titanium dioxide and the respective carboxylic acids (Franch et al. 2002).

9.5.6

Degradation of Aromatic Compounds

The heterogeneous photocatalysis based on titanium dioxide has been considered as a potential candidate to the remediation of hazardous benzene and phenol derivatives, given the potential threat to human health and the environment that most of these compounds pose. Amongst them, the World Health Organization (WHO) has classified Benzene, Toluene, Ethylbenzene and Xylenes (BTEX) as high risk in terms of their effects on humans (Nourmoradi et al. 2012), while others such as Chlorophenols (CPs) are classified in category 2B of IARC as possibly carcinogenic to humans (World Health Organization 2004). Nevertheless, this class of organic molecules typically presents a series of challenges related to their removal, considering their resilience in bioreactors. The mineralisation of BTEX was investigated on supported titanium dioxide nanopowders (Fard et al. 2013), as an alternative to slurry reactors. The study analysed the possibility of a complete removal of these compounds from real polluted wastewater. Different process parameters were considered, such as the source and wavelength of the UV light, either artificial or natural, the promoting effect of H2O2 if added, the effect of foreign cations or anions such as Ca2+ or CO23. Interestingly, considering the results of this study, the other ions present in solution as Ca2+ or CO32− would compete with the oxidising species, thus decreasing the

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oxidation efficiency (Chiou et al. 2006). The combination of artificial UV light and H2O2 on titanium dioxide films led to the mineralisation of 90% of BTEX, while pH variation had slight or no impact. The presence of cations or anions for those studied resulted in a drawback for the process efficiency since they represented competitor agents to the organic molecules for the free radicals generated on TiO2. Therefore, an upstream pre-treatment may be necessary to achieve the photocatalytic oxidation efficiency of titanium dioxide when such ions are present. Another study considered the degradation of BTEXs in gas phase on transition metal-doped titanium dioxide immobilised on fibreglass cloth (Laokiat et al. 2011). The material doping allowed for enhanced visible light absorption, and a complete removal of 70% of BTEX was registered for V-doped titanium dioxide. Although both study evidence the relevant contribution in BTEX remediation, significant comparisons can be drawn only on the material itself and on its efficiency towards these molecules. Experimental set-ups remain substantially different since catalyst loading, contaminant concentration, type of UV light and fluid dynamics are frequently changed. Titanium dioxide can be successfully implemented in different remediation systems thanks to its versatility without limiting the potential applications to specific liquid effluents or treatment set-ups. Polycyclic Aromatic Hydrocarbons (PAH), classified as significant human health risk (Kalf et al. 1997), can also be oxidised by titanium dioxide substrates via photocatalytic degradation (Zhang et al. 2008). It was demonstrated that phenanthrene (PHE), pyrene (PYRE) and benzo[a]pyrene (BaP), can be degraded up to 50% of the original concentration with a low loading of 0.5% wt of commercial P-25 titanium dioxide. Furthermore, it was reported that the titanium loading did not significantly affect the result, which is in good accordance with previous studies, reporting that an increase in loading of more than 0.5 g/L did not lead to significant further degradation. The presence of a threshold in titanium dioxide loading has been already demonstrated by other studies, reporting that above an upper catalyst concentration (Hong et al. 2001) no further improvements can be obtained. This result has been related to a non-uniform light distribution and further scattering among the solution, with a consequent slower reaction rate. The promising results obtained for oxidation of a wide range of benzene derivates as already shown, suggests it could be applied for destruction of other hazardous compounds representing a high risk to the environment and to human health. Such compounds include chlorophenols, chlorinated phenolic rings with resilience in water media. The application of titanium dioxide as a photocatalytic substrate for the complete mineralisation has been considered as a possible efficient remediation strategy.

9.5.7

Impact of Morphology and Microstructure

Morphological and microstructural parameters play an important role in regards to the photocatalytic performance of the materials. The crystallinity, face orientation,

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specific surface area, crystallite size or particle size are key parameters which will affect electron transfer and photocatalytic activity. Face orientation is known to play an important role, since anatase facets {001} were found to be more active in photocatalysis than the thermodynamically stable 101 (Jung et al. 2012). This effect was attributed to the inner instability due to higher surface energy, 0.91 J m−2 for {001} facet and 0.44 J m−2 for {101} facet, which would lead to preferential reactive sites on these planes (Sajan et al. 2015). However, the {101} crystals are usually prevalent up to 90%, since the crystal growth reduces significantly the quantity of the less stable {001} facets, therefore specific synthesis pathways are required for single {001} crystal growth. Interestingly, a synergetic effect was found by the addition of dopant into the structure as non-metals during the hydrothermal process that is normally followed to produce selective growth of {001} facets (Liu et al. 2009; Xiang et al. 2011). A deeper investigation of single crystal growth is however strongly advisable since the hydrothermal treatment requires HF as capping agent, a risky chemical leading to potential work safety hazard. Another key parameter well known for its impact on AOP is specific surface area. In this regard, a high specific surface area is beneficial since it generates a higher density of localised states, involving electrons between the conductance and the valence band (Mott and Allgaier 1967). These localised states play an important role in transferring the electric charge within adsorbed molecules and the surface, while providing trapping sites for charge carrier, therefore preventing h+/e− recombination (Hanaor and Sorrell 2010; Barzykin and Tachiya 2002). Anatase was shown to have a higher density of localised states and therefore a higher adsorbance of hydroxyl radicals, which are part of the photodegradation mechanism and lower charge recombination compared to pure rutile (Ding et al. 2000; Augustynski 1993). The role of particle size and crystallite growth has been debated, since it is believed that smaller particles possess and higher surface area, which is beneficial to the photocatalytic activity. However, the recombination process of charge carriers on the surface must be considered. A higher photonic efficiency is induced by a smaller size, leading to higher interfacial transfer rate (Serpone et al. 1995). The delocalisation of molecular orbitals on the surface leads to a red shift in the band gap when the bulk material is reduced with the decrease in size. However, when the size is too small, size quantisation is induced generating confinement of charge carriers that hinders delocalisation (Brus 1986; Brus 1984). Therefore, the band gap of nanoparticles increases below a certain threshold (Lin et al. 2006). This study, interestingly, reported that the band gap decrease from 3.238 to 3.173 eV when the particle reduced from 29 to 17 nm, and increase again up to 3.289 eV when the size was further reduced to 3.8 nm. This effect can be clearly seen from Fig. 9.2. In this case, the optimal photocatalytic activity was found for particles of 14 nm, although the band gap was higher than for particles of 6 nm. This effect is likely due to the combination of effects due to charge dynamics, specific surface area and light absorption efficiency.

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Fig. 9.2 Variation of band gap of pure anatase over different particle size (Kočí et al. 2009)

Trapping sites for charge recombination are made available across the surface of the material, and charge carriers can facilitate recombination thus shortening the time needed for site transfer. Considering the short time lag from the migration of the charge carrier from the bulk to the surface, the recombination occurs more rapidly than the separation on trapping sites (Zhang et al. 1998). Different studies have confirmed that the optimal particle size is around 10 nm. One study reported 11 nm as optimal particle size for pure titanium dioxide (Zhang et al. 1998). The degradation of trichloroethylene exhibited a maximum at 7 nm of titanium dioxide primary particle size, defined as crystal size (Maira et al. 2000). Furthermore, the lower band gap of rutile compared to anatase can be confirmed by its larger crystallite size, typically around 32 nm at the end of thermal growth (Zhang et al. 2000, 2014; Patra et al. 2015), with less photocatalytic efficiency than pure anatase as reported (Tayade et al. 2007). A review of different studies has considered the effect of both surface area and particle size to evaluate the degradation of two of the most investigated organic contaminants, methylene blue and phenol, respectively, as shown in Fig. 9.3 and summarise in Tables 9.2 and 9.3, respectively. A linear increase in MB degradation can be observed when the surface area is increased, while low activity is registered for rutile in general. However, the lack of consistency among the studies in terms of catalyst load and initial concentration of the organic compound does not allow to draw general remarks. The calculations were made from the Langmuir–Hinselwood kinetic model for high titanium dioxide loading, which are expected to have low influence on the photocatalytic efficiency above a loading threshold in the range of 2–5 mg/l as demonstrated in paragraph 3. Interestingly, in Fig. 9.3b the effect of particle size for anatase seems to follow a logarithmic law plateauing slightly above 20 nm. The lowest particle size,

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Fig. 9.3 a Specific surface area and b nanoparticle size influence on degradation of organic compounds for 1-h reactions

Table 9.2 Variation of specific surface area across titania phase and correlation to methylene blue degradation Specific surface area (m2/g)

Methylene blue degradation (%)

Titania phase

References

8.9 30 40 67 91 123 124 134.4 209 212 2 8.9 15 15 25 220

70 77 72 40 70 60 100 60 100 100 85 20 21 35 26 20

Anatase Anatase Anatase Anatase Anatase Anatase Anatase Anatase Anatase Anatase Rutile Rutile Rutile Rutile Rutile Rutile

58.5 50 56 50 50

40 55 75 85 35

Epling and Lin (2002) Inagaki et al. (2004) Inagaki et al. (2004) Awati et al. (2003) Awati et al. (2003) Kim and Kwak (2007) Tayade et al. (2007) Le et al. (2012) Kim and Kwak (2007) Kim et al. (2009) Tayade et al. (2007) Epling and Lin (2002) Inagaki et al. (2004) Inagaki et al. (2004) Inagaki et al. (2004) Mohamed and Al-Esaimi (2006) Le et al. (2012) Randorn et al. (2004) Nawi and Zain (2012) Kim et al. (2009) Yang et al. (2014)

P-25 P-25 P-25 P-25 P-25

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Table 9.3 Variation of nanoparticle size across titania phase and correlation to phenol degradation Nanoparticle size (nm)

Phenol degradation (%)

Titania phase

References

4.5 5

6 43

Anatase Anatase

6 10

31 48

Anatase Anatase

12.8 14.1 17 32

32 80 40 23

Anatase Anatase Anatase Anatase

63 160 330 7.2 18.5 34 40.8 55.6 20 20 26 30 30 30 30

40 48 44 80 30 25 25 5 75 60 60 94 30 45 60

Anatase Anatase Anatase Rutile Rutile Rutile Rutile Rutile P-25 P-25 P-25 P-25 P-25 P-25 P-25

Liu et al. (2008) Choquette-Labbé et al. (2014) Liu et al. (2008) Choquette-Labbé et al. (2014) Liu et al. (2008) Gao and Zhang (2001) Lin et al. (2011) Choquette-Labbé et al. (2014) Balázs et al. (2008) Lin et al. (2011) Lin et al. (2011) Gao and Zhang (2001) Gao and Zhang (2001) Hong et al. (2005) Gao and Zhang (2001) Lin et al. (2011) Liu et al. (2008) Hadj Salah et al. (2004) Balázs et al. (2008) Hong et al. (2005) Chiou et al. (2008) Gao and Zhang (2001) Lin et al. (2011)

for anatase, is found around 3 nm and corresponds to the lower photocatalytic degradation of phenol, which is consistent with the described quantum size effect. It can also be noticed that P-25, in this case, is more competitive than pure anatase or pure rutile in most of the cases, and this can be ascribed to the expected synergetic effect of the two phases for the commercial product. The electronic properties of titanium dioxide have been extensively investigated primarily to understand the differences between the different titanium dioxide phases. Strategies to modify the band gap and favour the absorption into the visible light range were developed, which includes primarily the introduction of a foreign atom as a dopant into the titanium dioxide lattice to enhance the heterogeneous photocatalytic pathways.

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Conclusions

This review provided a comprehensive overview of advanced routes to generate nanotextured and nanoporous titania materials. A correlation between the nanostructured materials and their catalytic properties for the remediation of organic compounds from wastewater effluents are also highlighted and discussed. The discussion was focused on the critical impact of surface properties and crystallinity on the performance of the titania catalytic materials and on their suitability for application as both combined separation materials and reactive surfaces. The design of doped titania materials active in the visible range is a frontier in the scalability and application range of such structures in membrane separation. In addition, key challenges to overcome include the need to control tube-to-tube interactions as well as overall physical cohesion of the nanoporous network, to yield more stable and efficient reactor materials. Acknowledgements The team acknowledges the ARC for funding under the Linkage LP140100374 project. They also acknowledge Prof. Peter Hodgson for support and advice.

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Nam, C. T., Yang, W.-D., & Duc, L. M. (2013). Solvothermal synthesis of TiO2 photocatalysts in ketone solvents with low boiling points. Journal of Nanomaterials, 2013, 11. Narayan, R. J., Monteiro-Riviere, N. A., Brigmon, R. L., Pellin, M. J., & Elam, J. W. (2009). Atomic layer deposition of TiO2 thin films on nanoporous alumina templates: Medical applications. JOM Journal of the Minerals Metals and Materials Society, 61(6), 12–16. Nawi, M. A., & Zain, S. M. (2012). Enhancing the surface properties of the immobilized Degussa P-25 TiO2 for the efficient photocatalytic removal of methylene blue from aqueous solution. Applied Surface Science, 258(16), 6148–6157. Noguchi, T., Fujishima, A., Sawunyama, P., & Hashimoto, K. (1998). Photocatalytic degradation of gaseous formaldehyde using TiO2 film. Environmental Science and Technology, 32(23), 3831–3833. Nourmoradi, H., Nikaeen, M., & Khiadani, M. (2012). Removal of benzene, toluene, ethylbenzene and xylene (BTEX) from aqueous solutions by montmorillonite modified with nonionic surfactant: Equilibrium, kinetic and thermodynamic study. Chemical Engineering Journal, 191, 341–348. Okimura, K., Maeda, N., & Shibata, A. (1996). Characteristics of rutile TiO2 films prepared by r.f. magnetron sputtering at a low temperature. Thin Solid Films, 281–282, 427–430. Ollis, D. F., & Al-Ekabi, H. (1993). Photocatalytic purification and treatment of water and air. In Proceedings of the 1st International Conference on TiO2 Photocatalytic Purification and Treatment of Water and Air, London, Ontario, Canada, November 8–13, 1992. The Netherlands: Elsevier. Patil, S. R., Akpan, U., & Hameed, B. (2015). Photocatalytic activity of sol-gel-derived mesoporous TiO2 thin films for reactive orange 16 degradation. Desalination and Water Treatment, 53(13), 3604–3614. Patra, S., Davoisne, C., Bouyanfif, H., Foix, D., & Sauvage, F. (2015). Phase stability frustration on ultra-nanosized anatase TiO(2). Scientific Reports, 5, 10928. Paulose, M., Mor, G. K., Varghese, O. K., Shankar, K., & Grimes, C. A. (2006). Visible light photoelectrochemical and water-photoelectrolysis properties of titania nanotube arrays. Journal of Photochemistry and Photobiology A: Chemistry, 178(1), 8–15. Peng, X., & Chen, A. (2004). Aligned TiO2 nanorod arrays synthesized by oxidizing titanium with acetone. Journal of Materials Chemistry, 14(16), 2542–2548. Peterson, R. A., Anderson, M. A., & Hill, C. G. (1994). Development of TiO2 membranes for gas phase nanofiltration. Journal of Membrane Science, 94(1), 103–109. Petrochenko, P. E., Kumar, G., Fu, W., Zhang, Q., Zheng, J., Liang, C., et al. (2015). Nanoporous aluminum oxide membranes coated with atomic layer deposition-grown titanium dioxide for biomedical applications: An in vitro evaluation. Journal of Biomedical Nanotechnology, 11 (12), 2275–2285. Pierre, A. C., & Pajonk, G. M. (2002). Chemistry of aerogels and their applications. Chemical Reviews, 102(11), 4243–4266. Prakasam, H. E., Shankar, K., Paulose, M., Varghese, O. K., & Grimes, C. A. (2007). A new benchmark for TiO2 nanotube array growth by anodization. The Journal of Physical Chemistry C, 111(20), 7235–7241. Pruden, A. L., & Ollis, D. F. (1983). Degradation of chloroform by photoassisted heterogeneous catalysis in dilute aqueous suspensions of titanium dioxide. Environmental Science and Technology, 17(10), 628–631. Rahimpour, A., Jahanshahi, M., Rajaeian, B., & Rahimnejad, M. (2011). TiO2 entrapped nano-composite PVDF/SPES membranes: Preparation, characterization, antifouling and antibacterial properties. Desalination, 278(1–3), 343–353. Rahimpour, A., Madaeni, S. S., Taheri, A. H., & Mansourpanah, Y. (2008). Coupling TiO2 nanoparticles with UV irradiation for modification of polyethersulfone ultrafiltration membranes. Journal of Membrane Science, 313(1–2), 158–169. Rai, V. R., & Agarwal, S. (2009). Surface reaction mechanisms during plasma-assisted atomic layer deposition of titanium dioxide. The Journal of Physical Chemistry C, 113(30), 12962–12965.

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Chapter 10

Addressing Water Scarcity in Tamilnadu: New Perspective Ashok Natarajan

Abstract This chapter discusses a few case studies of projects completed by Tamilnadu Water Investment Company (TWIC) to ameliorate water stress in the neighbourhood by implementing water reuse and seawater desalination system. This chapter also discusses how the public–private partnership helped to address the issue of water security as well as bring about major savings in cost and time.








Keywords Desalination Reverse osmosis Feasibility studies Selection of technology Water management and treatment

10.1

Introduction

Tamil Nadu is one of the 29 states of India and the eleventh-largest state by area. It has a population of 72,147,030 (census 2011), which is the sixth-most populous. The state has the second largest state economy in India with US$210 billion in gross domestic product after Maharashtra (Wikipedia). The annual rainfall of the state is about 945 mm of which 48% is through the north east monsoon, and 32% through the south west monsoon. Since the state is entirely dependent on rains for recharging its water resources, monsoon failures lead to acute water scarcity and severe drought. Currently, Tamil Nadu is facing a water deficit of more than 11% and it is predicted to increase in the coming years. Tamil Nadu is dependent on its neighbouring states due to lack of flowing rivers in the state. To ameliorate the water stress, Tamil Nadu has taken steps to implement water reuse and install seawater desalination systems. In this chapter, the evaluation processes carried out in constructing seawater reverse osmosis plants (SWRO) in two districts namely Thoothukudi and Ramanathapuram have been discussed briefly.

A. Natarajan (&) Tamilnadu Water Investment Company, Chennai 600032, Tamil Nadu, India e-mail: [email protected] © Springer International Publishing AG, part of Springer Nature 2019 M. Pannirselvam et al. (eds.), Water Scarcity and Ways to Reduce the Impact, Applied Environmental Science and Engineering for a Sustainable Future, https://doi.org/10.1007/978-3-319-75199-3_10

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10.1.1 Thoothukudi District Thoothukudi district is an administrative district of Tamil Nadu state and it is situated in the south-eastern part of TamilNadu, which is an arid and water scarce region. The city of Thoothukudi is the district headquarters. Thoothukudi district spreads over an area of 4621 km2. The district comprises of one municipal corporation, two municipalities, 19 town panchayats and 1718 habitations in 12 blocks having 462,010 households and a population of 17,50,176 (Census 2011).

10.1.2 Ramanathapuram District Ramanathapuram district is an administrative district of Tamil Nadu state and it is situated in the south-eastern part of the TamilNadu, which is an arid and water scarce region. The city of Ramanathapuram is the district headquarters. Ramanathapuram district has an area of 4123 km2. It is bounded on the north by Sivaganga Ddstrict, on the northeast by Pudukkottai district, on the east by the Palk Strait, on the south by the Gulf of Mannar, on the west by Thoothukudi district and on the northwest by Virudhunagar district. The district Comprises of four municipalities, seven town panchayats and 2520 rural habitations in 11 blocks.

10.2

Details of Population and Water Demand

Table 10.1 lists the details of population and water demands of Thoothukudi and Ramanathapuram districts. Both districts have populations over one million and Thoothukudi district’s population is expected to increase 0.47% per annum and Ramanathapuram district’s population is expected to increase 0.47% per annum 0.93% per annum. Urban demand and rural demand were considered to be 135 and 55 LPCD for both district and did not expect to increase over time.

10.3

Need for Desalination Plant

Considering the existing scenario of non-sustainable and drinking water quality of groundwater in these districts, the Honourable Chief Minister of Tamil Nadu announced in the Floor of Assembly on 10th April in 2013, under Rule 110 of Legislative Assembly that desalination plants of 100 MLD capacity, each will be installed in Ramanathapuram and Thoothukudi districts, as a permanent measure to provide drinking water to the public for all seasons. In the above context, Tamilnadu Water Supply and Drainage Board (TWADB), Chennai entrusted the

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Addressing Water Scarcity in Tamilnadu: New Perspective

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Table 10.1 Current and future total water demand in Thoothukudi and Ramanathapuram districts Year Urban population Rural population Total population Rate of supply for urban (LPCD) Rate of supply for rural (LPCD) Demand at delivery point (LPCD) Existing supply from various CWSS (LPCD) Net demand (LPCD) Transmission losses at 10% (LPCD) Demand inclusive of water loss (LPCD) Industrial demand and rounding off (LPCD) Total demand (LPCD)

Thoothukudi district 2016 2031

2046

Ramanathapuram district 2016 2031 2046

240,900 885,050 1,125,950 135

273,500 927,300 1,200,800 135

312,600 971,550 1,284,150 135

377,920 1,044,590 1,422,510 135

468,810 1,150,520 1,619,330 135

582,950 1,256,460 1,839,410 135

55

55

55

55

55

55

81.20

87.92

95.64

108.47

126.57

147.80

20.99

22.37

24.00

46.45

54.12

63.33

60.21

65.55

71.64

62.02

72.45

84.47

6.02

6.56

7.16

6.20

7.24

8.45

66.23

72.11

78.80

68.22

79.69

92.92

8.77

17.89

26.20

6.78

10.31

12.08

75.00

90.00

105.00

75.00

90.00

105.00

assignment to Tamilnadu Water Investment Company (TWIC) Limited, Chennai for conducting planning study and preparation of pre-feasibility report including financial viability, for setting up of either one number of 100 MLD or more than one plants of various capacities, totalling 100 MLD SWRO desalination plants in these districts. Field study and survey work were carried out to evaluate each site for access to good quality seawater, brine disposal and dispersion, physical suitability for construction of desalination plant, e.g. soil condition and flooding, acceptability from an environmental point of view and access to electrical power. Thus, the following activities were performed. • Obtained present population and existing water supply scheme and infrastructure details. Identified candidate site by carrying out reconnaissance survey. • Obtained data/records of Government lands, for fixing up the site in and around to the probable locations.

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• Obtained details from TNEB on the source and availability of electrical power to the site; preliminary assessment was made on the power requirement for each site. • Collected seawater samples for analysis of water quality parameters. • Carried out oceanographic survey covering, bathymetry, seabed geology, wind, current, tides, waves and marine ecology and biology.

10.3.1 Choice of Technology Almost all the new stand-alone desalination plants, which have come up worldwide in the recent past, are based on reverse osmosis as this has a distinct edge over other desalination technologies in such applications (Fig. 10.1). Chennai Metro Water has also selected seawater reverse osmosis technology for the Minjur (100 MLD) and Nemmeli (100 MLD) plants and the pre-feasibility report was prepared by TWIC. While Minjur plant used conventional filtration systems for pretreatment, Nemmeli plant used disc filters and ultrafiltration membranes for the same. The cost of Minjur and Nemmeli plants were US$82.4 M and US$85.34 M (current value), respectively.

Fig. 10.1 Schematic of a seawater reverse osmosis plant with intake of several hundred meters from the shore and with bine discharged back to the sea through diffusers

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Addressing Water Scarcity in Tamilnadu: New Perspective

10.4

191

Site Selection and Sizing of Plant Capacity

Potential sites for a desalination plants were identified as a result of meetings with the TWAD board officials and knowledge of local conditions. Sites were selected to leverage existing distribution infrastructure. In Thoothukudi district, the site selection process initially identified 10 sites that represent a wide range of potential locations. These sites are Manapadu, Tharuvaikulam, Veppalodai, Sippikulam and Vaippar/Vembar. Out of 10 sites initially identified, five sites were eliminated due to non-suitability of engineering parameters like seawater depth, intake and outfall, land availability, potential environmental and social concerns or the potential lack of community acceptance. The site identified for further studies are Alanthalai, Kayalpattinam South, Kayalpattinam North, Tharuvaikulam and Vaippar. Similarly, in Ramanathapuram district, the site selection process initially identified 10 sites that represent a wide range of potential locations. These sites are Kannirajapuram, Narippaiyur, Kuthiraimozhi, Valinokkam, Chinna Ervadi, Kilakarai, Uchipuli/Mandapam, Keelanagachi/Mandapam, Chithrakottai/ Devipattinam and Karankadu/near Thondi. After initial screening, further study was done for the selected site to assess the suitability for setting up the SWRO Plant based on the following criteria as present in Table 10.2.

10.4.1 Techno Economic Feasibility Option Based on the above evaluations, the following two options were shortlisted for Thoothukudi district: Option-1 (Multiple Location): Grouping the beneficiaries considering the proximity for conveying product water from two supply centres, one at Alanthalai another at Vaippar. Option-2 (Single Location): Total beneficiaries conveyed product water from one supply centre, i.e. at Vaippar considered the best ranking. Similarly, for Ramanathapuram district, the following two options were shortlisted: Option-1 (Multiple Location): Grouping the beneficiaries considering the proximity for conveying product water from two supply centres, one at Kuthiraimozhi another at Keelanagachi. Option-2 (Single Location): Total beneficiaries conveyed product water from one supply centre, i.e. at Keelanagachi considered the best ranking. Based on the above, the grouping of beneficiaries, capacity of plant for multiple location and single location are estimated as detailed below:

Y

Y

Y

Y

N

Y

N

Y

Y

Y

Y

Y

N

Y

Y

Y

Extend of land available for minimum 20 MLD capacity

Proper access to land/ site identified

Water quality— requires extensive pretreatment

Seabed sediment— affect the intake water quality

Suitability for intake and brine discharge (proper dispersion)

Suitable depth availability— bathymetry

Nature of geology of seabed—suitable for execution

Y

Y

Y

N

Y

N

Y

Y

Y

N

N

Y

Y

Y

Y

Y

Y

Y

Y

N

Y

Y

Y

Y

Vaippar

Y

Y

Y

N

Y

Y

N

Y

Y

Y

Y

N

Y

Y

Y

Y

Kuthiraimozhi

Narippaiyur

Tharuvaikulam

Ramanathapuram district Kayalpattinam North

Alanthalai

Kayalpattinam South

Thoothukudi district

Availability of land close to sea

Criteria

Table 10.2 Checklist to evaluate the site acceptability of SWRO desalination plant site

Y

N

N

Y

Y

Y

N

Y

Chinna Ervadi

Y

Y

Y

N

Y

Y

Y

Y

Keela Nagachi

(continued)

Y

N

N

Y

Y

Y

N

Y

Karankadu

192 A. Natarajan

Y

Compliance with CRZ regulations

Note Y Yes, N No

Easier for statutory clearances

Y

Acceptability from social point of view no disturbance to human settlement and fishing

Marine fauna and fisheries

Y

Y

Y

Y

Acceptability from an environmental perspective

Ecologically non-sensitivity region

Y

Y

N

Y

Y

Y

N

Y

Y

Y

Y

Y

Y

Y

Y

Y

Y

Y

Y

Y

Access to electrical power supply

Y

Y

Y

Suitability for plant construction—soil and flooding

Y

Narippaiyur

Kayalpattinam South

Alanthalai

Y

Y

Y

Y

Y

Kuthiraimozhi

Ramanathapuram district

Thoothukudi district

Y

N

Y

Y

Y

Chinna Ervadi

Y

Y

Y

Y

Y

Keela Nagachi

Y

N

Y

Y

Y

Karankadu

Criteria Vaippar

Table 10.2 (continued) Tharuvaikulam

Addressing Water Scarcity in Tamilnadu: New Perspective

Kayalpattinam North

10 193

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10.4.2 Financial Analysis Financial analysis was conducted for an evaluation period of 3½ years of development and construction and 30 years of operation. The construction was to start in 2016 and expected to be completed by 2018. Evaluation was carried under three financing options namely, (i) 100% grant (ii) 50% grant and 50% loan and (iii) under PPP (with 70% loan and 30% equity). Based on the above, the levelized cost and the break even tariff were worked out for various funding patterns. The Tamilnadu government has approved the pre-feasibility and financial model and sanctioned two 60 MLD units in phase one at Kuthiraimozhi and Alanthalai. It was decided to go for design, build, operate and transfer (DBOT) model with 25 years of operations and maintenance. This was the first model adopted by Tamil Nadu government based on pre-feasibility study like the one followed by the states in Australian Coast. This unique experiment by Tamilnadu government would help to address the issue of water security in the two districts as well bring about major savings in cost and time (Fig. 10.2 and Table 10.3).

10.5

Concluding Remarks with a Brief Description of Tamil Nadu Water Investment Company

Tamil Nadu Water Investment Company (TWIC) is a pioneering developer of water projects in India promoted by Infrastructure Leasing and Financial Services Limited (IL&FS), 54% and Government of Tamil Nadu (GoTN), 46%. TWIC was formed to promote the first public–private partnership (PPP) in water sector, namely the New Tirupur Water Project (185 MLD). TWIC has been actively involved in developing and implementing projects across several sectors. Its expertise ranges from urban water and sewerage systems,

Fig. 10.2 Photo of the author of this chapter Mr. Ashok Natarajan and his colleagues with local community members

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Table 10.3 Supply centre options for Thoothukudi and Ramanathapuram districts with intermediate and ultimate demand Option

1 2 3

Thoothukudi district Supply centre

Intermediate demand (MLD)

1-Multiple location

Alanthalai

50

Vaippar

40

2-Single location

Vaippar (combined capacity)

90

Ramanathapuram district Ultimate demand (MLD)

Supply centre

Intermediate demand (MLD)

Ultimate demand (MLD)

60

Kuthiraimozhi

20.0

45

Keelanagachi

70.0

80.0

105

Keelanagachi

90.0

105.0

25.0

desalination, industrial effluent management, and recycling. TWIC’s role in all these areas would be to provide its clients with end to end solutions through a comprehensive understanding of the problem, selection of appropriate technology solutions, design development, arranging finance, procurement of contractors, supervision of implementation and operation and maintenance. TWIC helps its clients in developing projects from concepts to implementation through a model aimed at reducing life cycle costs within a sustainable delivery framework. The following awards were awarded to TWIC by reputed international institutions: (i) Global Water Intelligence Award 2014 by Global Water intelligence for Tirupur Central Effluent Treatment Plant Zero Liquid Discharge (ZLD) project as “Highly Commended” under the Industrial Water Project of the year category and has also called as a “phoenix rising from the ashes of an environmental catastrophe”. (ii) TWIC was awarded with Industrial Project for the Year 2014 by the Water Reuse Association, USA for Tirupur ZLD project, which recognizes projects whose significance and contributions to the community continue to advance the water reuse industry. Tirupur ZLD Project has demonstrated continued dedication to the water reuse community. (iii) TWIC has been awarded the Certificate of Excellence for the Hydraulic Modelling for “Vellore Water Supply Improvement Scheme” by Bentley USA.

References http://www.engrreview.com/technology-driven-twic-chennai-gets-global-recognition-for-tirupurzero-liquid-discharge-project/. Viewed on July 27, 2017. http://www.twic.co.in. http://www.waterlossasia.com/index.php/the-conference/conference-speakers/10-conferencespeakers/30-k-ashok-natarajan. Viewed on July 27, 2017.

Chapter 11

Repair or Replace: Technologies Available for Trenchless Remediation of Existing Infrastructure Peter Marchant

Abstract Management of water networks is now seen as managing a resource rather than conveying a product to a convenient outlet such that systems frequently act as detention conduits so water tightness is fundamental in the performance of the asset. Most frequently, the older assets lie in our largest cities which are now of high value and highly populated urban areas. Traditional open cut excavation to repair or replace these assets is disruptive as well as expensive and is often no longer recognised as an acceptable solution in today’s world. This chapter explores what systems are available and what can be undertaken with modern day technology.










Keywords Water networks Sliplining Pressure line Roll down Cast-in-place pipe Buried flexible pipelines Cast insitu concrete lining




11.1




Introduction

No matter where in the world, there is infrastructure containing underground storm drains and conduits that are at or nearing the end of their useful lives. Networks carry an increasing risk of collapse, which leads to unacceptable problems with disruption, as well as wasted resource and unacceptable pollution if the asset fails. Today, we are looking to increase the capacity of these systems and asking them to do more than that was ever expected when they were first designed and constructed. What was considered as revolutionary 10 years ago is now commonplace. Technology has forged ahead the ability to rehabilitate assets once restricted to small diameters, which is now available across different shapes and profiles to medium and large diameter infrastructures. So, how can we guarantee that our remediation proposals will meet the structural requirements necessary to extend the P. Marchant (&) ITS Pipetech Pty Ltd, Seven Hills, Australia e-mail: [email protected] © Springer International Publishing AG, part of Springer Nature 2019 M. Pannirselvam et al. (eds.), Water Scarcity and Ways to Reduce the Impact, Applied Environmental Science and Engineering for a Sustainable Future, https://doi.org/10.1007/978-3-319-75199-3_11

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life of our critical underground infrastructure assets when limited ground information and condition assessment is available? When considering a project for rehabilitation there are a number of technologies available that can be used to develop a design that achieves a solution that is fully compliant with Australian design standards, however, some of these carry more risks than others. The current design codes used for relining rehabilitation across Australia actually relate to new works construction. These standards are assimilated to reflect the conditions that are presumed to be present with the existing structure and surrounding soils, however, without specific factual data, i.e. a ground investigation report and condition assessment, some of the assumptions made carry a significant risk that the design must accommodate or else premature failure could occur. How we mitigate this risk to ensure that the design proposal accommodates the contractual scope and duty that will be applied to the structure will be dependent on the technology that is being proposed and the factors around how much these methodologies are reliant on the assumptive criteria, and therefore risk. Often, when information is unavailable worst-case scenarios are adopted which drive over conservative design and ultrasensitive risk assessment. This then questions the efficiency of the proposal and the economics which in turn raises the effectiveness of a rehabilitation against a new build. This chapter explores the current technologies available for structural rehabilitation of our critical subsurface infrastructure to current Australian standards to achieve solutions that are compliant. It looks at how much risk needs to be accounted for and considers other international standards that could be applied to mitigate some of the unnecessary cost to provide fully compliant structural solutions that will remain in service for up to 100 years.

11.2

Current Technology

There are many different lining methodologies currently available for pipe, culvert and tunnel rehabilitation all of which have advantages and disadvantages depending on the circumstances that are present at the site, where rehabilitation is being considered. The right selection of the most appropriate technology is often a difficult assessment to make as many different external pressures often influence the engineering attributes that the various systems are able to deliver. There is also a miss appreciation for what the technologies can deliver that frequently leads to the deployment of a technology that is not always the optimised solution to the problem. This chapter sets out to explain the different technologies available, how they are installed, what reliances is required from the host structure and what the advantages and disadvantages are against each technology.

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The principle technologies available are defined as either Flexible or Rigid—each behaves very differently and each has different associations with the local surrounding ground strata. Some of the technologies considered are summarised as follows: • • • • • • •

Sliplining, continuous and discrete Pressure reduction lining or rolldown Inverted cured-in-place pipe lining Expanded cured-in-place pipe Spiral section formed linings Fold and form linings In situ concrete structural lining

11.3

Site Considerations

When deciding what technology is most suitable for a culvert or pipe rehabilitation the following conditions should be reviewed and assessed prior to the design and proposal of any lining system. • • • • • • • • • • •

Size and condition of the host pipe Degree of deterioration and integrity of the host pipe and associated structures Condition, number and frequency of branch connections Active and passive loading Design life expectancy Soil and backfill condition Presence of Voiding Groundwater regime Location, proximity and access Chemical and fire resistance Future use and requirements

All of these will dictate which lining technology is the most suitable for the successful application.

11.4

Sliplining

Sliplining is the simplest and most common technique for renovating man-entry and non-man-entry pipelines. It basically entails pushing or pulling a new pipeline into the old one. The concept of using the ‘hole in the ground’ by installing a new pipe within the old is long established. Over the years, many different types of pipes have been used, including clay, concrete FRC, HDPE, PVC and fibreglass.

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Fig. 11.1 Continuous slipline

Fig. 11.2 Discrete slipline

There are two basic forms of sliplining, the first is using a continuous length of pipe—usually sections of HDPE pipe welded together on the surface and pulled or pushed into the host (Fig. 11.1), the second is discrete sliplining (Fig. 11.2), where individual small sections of pipe are joined together and pulled or jacked into place usually from within a pit where surface space is limited. Although, in theory, any material can be used for the new pipe, today polyethylene (HDPE) is the most common choice in smaller sizes (to 1200 mm) with fibreglass being the preferred material above this. The material is well established in

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the potable water and gas industries and is abrasion resistant and sufficiently flexible to negotiate minor bends during installation. It can be butt-fused into long lengths prior to being winched into the host pipe. In some cases, it will be necessary to space the pipe inside the host and grout the annulus between the host pipe and the inserted pipe in order to hold it firmly in position. The loss of cross-sectional area may be significant, particularly if the liner size is governed by the available diameter of the host pipe, which in the case of a badly deformed structure could be significantly less than the original diameter or the diameters of commercially available extruded pipes, or where the size must be further reduced to negotiate displaced joints in the host pipe. As a result of these limitations, plain sliplining has become less common than close-fit lining, but may still be the best choice in certain cases.

11.4.1 Advantages The following are the advantages of the sliplining: • Suitable for a wide range of pipe types and diameters—100–1500 mm nominal in HDPE and up to 3000 mm in fibreglass or concrete pipes installed with the assistance of hydraulic jacks • Wide option of liner material available • Relatively cheap simple process

11.4.2 Disadvantages The following are the disadvantages of the sliplining: • Loss of usable cross-sectional area compared to the original host pipe—Governed by the pressure rating required which determines the liner wall thickness • Launch and reception pits required • Lateral connections and junctions must be excavated from the surface and re-connected • Not suitable for sharp or tight radius bends

11.5

Pressure Line or Rolldown

Pressure line or roll down is a system that uses a polymer pipe (Fig. 11.3), usually Polyethylene (PE), with an outside diameter slightly greater than the host pipe ID to be lined. Sections of lining pipe are welded together using butt fusion to form a

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Fig. 11.3 Pressure line

continuous pipe, longer than the section that is to be lined. The PE pipe is pulled or jacked through a reducing die that reduces the diameter to enable it to be pulled into place inside the host without resistance. Once the liner is pulled into position the PE pipe relaxes and it regains its memory reverting back to its former diameter which creates a very tight compression fit inside the host pipe that does not require any grouting. Liner pipe can be preassembled on the surface allowing long lengths of lining to be undertaken from a single launch pit, lengths of 800 m are achievable in single pulls.

11.5.1 Advantages The following are the advantages of the pressure line: • • • • • • •

Ability to install long sections in one operation Quick Maximises available pipe diameter Flow capacity close to original pipeline design Chemically resistant to most substances Caters for high-pressure pipelines and rising mains High ware resistance

11.5.2 Disadvantages The following are the disadvantages of the pressure line: • • • •

Surface excavation is required for connection of laterals Not suitable for curved sections of pipe Not all HDPE pipe is suitable for reduction—dependent on the resin component Can incur long-term pipe damage if not undertaken properly

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203

Cured-in-Place Lining- Inversion Method

Cured in place inversion lining is a lining that is stuck inside the host pipe and an alternative to sliplining (Fig. 11.4) that has been used around the world for over 30 years. Inversion systems can be referred to as ‘soft lining’ or ‘cast-in-place pipe’ (CIPP). Cured in place inversion lining is a lining that is stuck inside the host pipe and an alternative to sliplining that has been used around the world for over 30 years. Inversion systems can be referred to as ‘soft lining’ or ‘cast-in-place pipe’ (CIPP). Although several competitive systems are available, the common feature is the use of a fabric tube impregnated with polyester or epoxy resin. The tube is inverted under pressure into the existing pipeline and inflated against the existing pipe wall, the resin is on the inverted surface, therefore, acts as a bonding agent to fix the lining into the host, the lining is then cured most commonly by re-circulating hot water or steam. CIPP systems create a close-fit ‘pipe-within-a-pipe’, which has quantifiable structural strength and can be designed to suit various loading conditions, however, in essence, this is a composite structure and reliant on some of the strength of the existing pipe. In the case of a severely deteriorated host pipe, structural longevity can be seriously compromised as the soft liner on its own has limited stand-alone structural strength. Cured in place liners can be manufactured to conform to almost any shape of pipe, making them suitable for lining of noncircular, e.g. ovoid cross sections. Range limitations are between 75 and 2400 mm. Some systems use a felt and fabric weave, which can stretch to accommodate small variations in cross-section. Since CIPP liners are flexible prior to cure and conform under pressure to the shape of host pipe, correct measurement of the pipe’s internal circumference is critical.

Fig. 11.4 CIPP inversion method

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Laterals can be reopened remotely after lining, but care must be taken during installation to ensure that surplus resin does not enter branches. The methodology for forming connections also relies on the insertion of a special sock commonly referred to a top hat. This top hat is inserted inside the existing liner and then inflated into the lateral. Issues here are the further reduction of the internal diameter and the integrity of the lateral connection inflating properly to seal the connection. This section is effectively a liner inside a liner inside the original host pipe. CIPP lining systems typically require the host pipe to be out of service during installation and cure. In gravity pipes, where flows are very low, it may be possible to plug any incoming pipes and to rely on the storage within the system. In other cases, flow diversion or over-pumping will generally be required. Although used mainly in non-man-entry pipelines, some systems are also suitable for the renovation of large diameter sewers and culverts. The liner wall thickness, weight and cost are the main limitations. CIPP systems were originally developed for gravity pipelines, but certain proprietary brands and techniques—especially for Potable water pipes— are available for pressure system lining.

11.6.1 Installation Thorough preparation is important for the success of a CIPP installation. The following are among the factors to be considered: • Intruding connections, encrustation and other hard deposits need to be removed by robotics before lining commences • Thorough cleaning of the pipeline, including removal of fat, grease and debris • Pre-lining repairs to missing inverts, etc. may be needed if the liner is to have as close to a circular cross section as possible • Flow diversion or bypass pumping during installation and cure. As laterals will also be blocked, consideration needs to be given to maintaining services to householders • Polyester resins give off styrene fumes with a strong odour during cure. This can be an irritant and ventilation around the site may be needed as well as a safe source of disposal for the curing water • Infiltration may adversely affect the curing of the resin. A “pre-liner” or pre-sealing may need to be installed Each proprietary system has its own methodology, and the description below is intended as a guide rather than as a statement of best practice. The majority of thermal-cure liners for gravity pipelines comprise a nonwoven fabric—usually polyester needle-felt—impregnated with polyester resin. The formulation of the resin can be adapted to suit different cure regimes and effluent characteristics. The liner fabric is usually coated on the outer face of the

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tube—which becomes the inner surface of an inverted liner—with a membrane of polyester, polyethylene, PVC or polyurethane, depending on the application. The membrane serves several functions—it retains the resin during impregnation and transportation, it retains the water (or air) during inversion, and it provides a low-friction, hydraulically efficient inner surface to the finished liner. Impregnation is normally carried out in the factory under a vacuum to exclude air and ensure the uniform distribution of resin. This is known as the wetting-out process. Depending on the characteristics of the resin, the liner may be delivered to site in a refrigerated vehicle, to prevent the curing reaction from starting prematurely. Insertion into the existing drain is carried out by an inversion process, wherein water (or sometimes air) pressure is used to turn the liner inside out as it is pushed out travels along the pipe. The following procedure is typical: 1. A scaffold tower is constructed over the insertion manhole to provide the head of water necessary to invert the liner. In deep sewers, the tower may be unnecessary. 2. A guide tube (which may be made from dry liner material) is installed between the inlet of the sewer and the top of the scaffold tower, with a rigid collar at the upper end to which the liner will be attached. 3. The leading end of the liner is turned inside out manually for a predetermined length, usually a few metres, and is then clamped to the collar of the guide tube. A hose is attached to the trailing end which will run within the full length of the liner after inversion. 4. Water is introduced into the turned-back section, which causes the liner to continue inverting through the guide tube and the host pipe. The pressure of water forces, the liner against the existing pipe wall. 5. When inversion is complete, the water inside the liner is circulated through a boiler unit, using the hose attached to the trailing end to ensure that hot water passes through the whole length of the liner. The rate of heat input is controlled according to the required cure regime of the resin. 6. Temperatures at various points on the surface of the liner are monitored with thermocouples. 7. Once cure has been achieved, the water is gradually cooled down before being released and tinkered off-site to designated waste disposal sites. 8. The ends of the liner are trimmed. Sometimes a few centimetres of liner may be left protruding from the manhole wall, which provides a better seal and also mechanically locks the liner in place 9. If necessary, lateral connections are reopened with a robotic cutter Some systems use a pre-liner which is installed within the host pipe before inverting the impregnated liner tube. The pre-liner is intended to stop surplus resin from entering lateral connections, and it also prevents contamination of the uncured resin by water infiltrating into the sewer or from surcharged connections.

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11.6.2 Advantages • • • • • •

Close-fit liner minimises loss of pipe bore on main lining Installed without surface excavation Suitable for noncircular shapes Longest international track record for close-fit liners Handles pipeline curves—vertical and horizontal to 22° 50-year design life

11.6.3 Disadvantages • Susceptible to wrinkling and cross-sectional irregularity if pre-lining repairs insufficient • Is only able to line to the smallest section of deformity present inside the existing pipe • Not suitable for severely deformed pipe • Bypass pumping usually needed • Limited ability to accommodate pipe diameter variations • Reliant on host pipe strength for composite design • Carcinogenic by-products from curing process • Top hat lateral connections reduce lining diameter even further • Low ring stiffness • Slow curing times

11.7

Cured-in-Place Lining-expansion Method

Cured in place expansion lining is a “tight-fit” alternative to inversion lining that has been used around the world for over 25 years (Fig. 11.5). It is sometimes referred to as structural or ‘cast-in-place pipe’ (CIPP). Although several competitive systems are available, the common feature is the use of a reinforced fibreglass and fabric tube impregnated with polyurethane or acrylic resin. The tube is inserted into the existing pipeline and inflated against the pipe wall, then cured using UV light. CIPP systems create a tight-fit ‘pipe-within-a-pipe’, which has quantifiable structural strength and can be designed to suit various loading conditions. Cured in place liners can be manufactured to conform to almost any shape of pipe, making them suitable for lining of noncircular, e.g. ovoid, box culvert and arch cross sections. The liner is manufactured 5% smaller than the host but has an inbuilt

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Fig. 11.5 CIPP expanded method

expansion factor of 20% to ensure that it secures a tight fit with no annular gap against the host structure. Since expanded liners are flexible prior to cure and conform under UV light to the shape of host pipe, correct measurement of the pipe’s internal circumference is critical. Laterals can be reopened remotely after lining with standard robotics, as there is no resin live in the insertion, there is no risk of contaminating the lateral. Furthermore, no top hats are required when making the connection as the opening can be machined and epoxy pointed with robotics from inside the pipe, consequently, the available bore of the lining remains constant throughout the process. CIPP lining systems typically require the host pipe to be out of service during installation and cure. In gravity pipes, where flows are very low, it may be possible to plug any incoming pipes and to rely on the storage within the system. In other cases, flow diversion or over-pumping will generally be required. Although used mainly in non-man-entry pipelines, some systems are also suitable for the renovation of large diameter sewers and storm culverts, currently, the maximum range is 100–1600 mm in profile. Expansion lining systems are mainly for gravity pipelines and are not suited to pressure systems.

11.7.1 Installation Thorough preparation is important to the success of a CIPP installation. The following are among the factors to be considered: • Intruding connections, encrustation and other hard deposits should be removed • Thorough cleaning of the pipeline, including removal of fat, grease and debris

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• Pre-lining repairs to missing inverts, etc. may be needed if the liner is to have a circular cross section, however, as the liners have a very high ring stiffness the spanning ranges of this form of liner are superior to felt liners • Flow diversion or bypass pumping during installation and cure. As laterals will also be blocked, consideration needs to be given to maintaining services to householders Each proprietary system has its own methodology, and the description below is intended as a guide rather than as a statement of best practice. Expansion thermos setting liners for pipelines comprise a composition of material including fabric and glass-fibre. The formulation of the resin can be adapted to suit different cure regimes and effluent characteristics. The liner fabric is usually coated on the outer face of the tube—which prevents the resin reaching the outer surface and therefore, the liner sticking to the host. The liner is fully structural and requires no strength from the host pipe and as such has a design life of 100 years. The inner resin impregnated surface hardens as the UV light train passes over being able to take instant load and without the need to remove contaminated curing fluid as with some inversion technologies. Impregnation is normally carried out in the factory under a vacuum to exclude air and ensure the uniform distribution of resin. This is known as the wetting-out process. A wet outliner will remain serviceable in an uncured condition for 15– 18 months.

11.7.2 Advantages • • • • • • • • • • • •

Close-fit expansion liner minimises loss of pipe bore Installed without surface excavation Suitable for noncircular shapes Longest international track record for close-fit liners Handles most pipeline curves-vertical and horizontal to 45° Top hat seals are not required for lateral connections Very strong ring stiffness able to support SM1600 loading Quick curing times No residual contaminates from curing process Structurally stand-alone 75-year design life Able to accommodate high levels of deformity in existing pipelines

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11.7.3 Disadvantages • Susceptible to wrinkling on bends above 45° • Bypass pumping usually needed

11.8

Fold and Form or Roll Down Liners

These are “close-fit” liners that are deliberately deformed prior to insertion, and then reverted to their original shape once in position so that they fit closely inside the host pipe (Fig. 11.6). Techniques commonly available involve folding the liner into a ‘U’ or ‘C’ shape prior to insertion, and then using heat and/or pressure to restore circularity. The process is typically limited to liners less than 1000 mm in diameter. Variations are available in polyethylene and PVC for both pressure pipes

Fig. 11.6 Fold and form

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and gravity sewers. The principle of folded liners is to reduce the effective size of the liner during insertion, and then to revert it to its original shape to produce a close fit within the host pipe. The liner is folded in the factory and delivered to site in coils. It is then winched into the host pipe. The liner can be installed in long lengths and around bends subject to pipe diameter and other factors. Once in place, the liner is heated internally to create a uniform temperature throughout the material. Reversion can be achieved progressively by inserting a rounding device into the upstream end of the liner, and propelling it by steam pressure to the downstream end. As the device progresses it expands the liner against the wall of the host pipe, and also forces out any liquids between the liner and the pipe. When flexible, the liner forms to the shape of the existing host pipe, and usually forms dimples at lateral connections. Pressure is maintained whilst the liner cools to a rigid state, after which the ends are trimmed and laterals reopened with conventional robotics. Groundwater infiltration may adversely affect the ability of the liner to reform to the shape of the host pipe. Folded PVC liners may be made from a type of PE or PVC, which is modified to allow the folding and reforming process. The degree of modification varies greatly between different products.

11.8.1 Advantages • • • •

Close-fit liner minimises loss of pipe bore Typically installed without digging Will accommodate slow radius bends Installation may be possible without bypass pumping

11.8.2 Disadvantages • Groundwater and infiltration can affect success of liner reversion • Shrinkage can be a problem after installation (particularly for polyethylene liners) • Susceptible to cross-sectional irregularities if pre-lining repairs are not sufficient • Surface excavation required for lateral connections

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211

Spiral Wound Liners

Commonly used in Australia, America and Japan but not so common in Europe, the spiral wound liner (Fig. 11.7) is developed as a smaller liner than the host as it is spirally wound into the host and is then secured in place with a cementitious grout that is injected into the intrados void between the host pipe inner surface and the external surface of the lining. The system consists of a single strip of PVC or HDPE material, profiled to shape which is then spirally wound into the existing pipeline via a mechanical winding machine positioned in the base of an existing access chamber. The edges of the strip either mechanically interlock via a male–female plastic joint or are heat welded together as it is spirally wound to form a continuous tube inside the host pipe. Generally, as the annular gap between the lining and the host can vary depending on the loading application, however, needs to be large enough to ensure that the grout travels to fully develop the lining. It is extremely important that the grout travels along the entire length of the lining and precise control and monitoring should be undertaken to prevent blockages and sections of the lining that are devoid of structural grout. This type of lining differs from the other types of close-fit liners in that • The strip liner is wound into the existing pipe to form a continuous tube then expanded to the final diameter inside the deteriorated pipe • Does not require a separate curing operation but is reliant on a second stage grout to secure the lining Spiral liner can be installed from a machine located at the base of a manhole or via a mechanical chain former that travels inside the host pipe—the latter is generally used for larger profile host pipes and culverts.

Fig. 11.7 Wound in linings

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11.9.1 Installation • The deteriorated pipeline is first cleared of debris, cleaned and CCTV inspected. Locations of lateral connections are logged. • The winding machine is lowered to the base of the manhole. The PVC profile is fed through the top of the manhole and into the winding machine. • The profile is wound in at a diameter smaller than the host pipe. The plastic edges of the male–female joint interlock to maintain the desired wind-in diameter.

11.9.2 Advantages • Can be installed without an overflow pumping system • Diameter can vary according to the actual diameter of the host pipe • Circular cross section remains constant and does not take shape of deteriorated host pipe • No shrinkage after installation • Can be installed from existing access points

11.9.3 Disadvantages • Requires structural grout to seal the gap between the lining and the host • Mechanical expansion joints not assured of achieving a regular shape • Requires top hats insertion for lateral connections that reduced internal diameter and creates steps inside the lining • Limited ability to line around bends • Requires uniform compacted backfill around existing pipe, which if severely deteriorated may affect design assumptions

11.10

Cast In situ Reinforced Concrete Linings

Cast in situ structural linings for larger profile structures where man-entry is possible (Fig. 11.8). This type of lining would be a bespoke design for each individual application, taking account of the existing structure condition, the shape of the host and the load requirements.

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Surface mounted

Fig. 11.8 Cast in situ lining

Lining designs can vary from 75 mm thick to 300 mm and can be reinforced with steel fibre or deformed steel bar as the need requires. Designs are classified as rigid elements that are structurally independent from the host pipe or culvert. The existing structures only serve to act as a retention formwork so the condition of the pipe/culvert and the surrounding ground is not as important to design consideration as for flexible linings and does not need to be referenced in the design. Profile shapes, shape transitions, bends and changes of gradient can all be accommodated in the final profile. In situ linings can also be installed in vertical structures. Preparation and the need to undertake pre-repairs of the existing structure is minimal, loose debris needs to be removed, however, missing masonry, holes and external voids, alignment abnormalities, etc. do not require pre-works as the injection of the concrete under pressure stabilises this as the lining is installed.

11.10.1

Advantages

• Can be installed without an overflow pumping system • Diameter and profile can vary according to the actual diameter of the host pipe or culvert • Suitable for all noncircular profiles • Fully structural and independent of the host structure • Can accommodate changes of shape • Can accommodate bends of any degree and radius

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• • • • • •

P. Marchant

Can be installed in vertical, inclined or horizontal aspects No shrinkage after installation 120-year design life Can be designed to take any loading with minimal cover Design for profiles from 1200 to 9000 mm Requires minimal surface access,(every 800 m)

11.10.2

Disadvantages

• Minimum wall thickness 75 mm • Not as fast as other technologies

11.11

Choosing the Correct Approach

Whilst several different technologies currently exist for the rehabilitation of sewer and stormwater culverts, they are all categorised under two basic design principles:, Flexible Liners and Rigid Liners. The behaviours associated with these two principles are fundamentally different and not to be confused. Rigid liners are sufficiently strong to withstand the live and dead loads as a designed element. The linings ability to resist imposed loads is improved with better soil interaction: embedment, but can be designed to be fully structurally independent in the event of poor soil condition, voiding and unstable ground. Flexible liners rely on their deformation from imposed loads and need to mobilise support from the surrounding soils, the embedment material surrounding the lining. The primary structural function of the liner is to distribute the vertical load into the surrounding soil. Only a small percentage of the imposed loads are carried by the liners, instead load is transferred around the liner into the surrounding bedding material, therefore, the design assumes that the soil interaction with the embedment will be the same as if a new flexible pipe was being laid. Whilst the principle for this is based on an approved standard in Australia AS2566 Pt 1 (1998), the basis for this standard relates to a new installation and it is not directly relevant to the refurbishment of an existing host structure. The designer must list the assumptions made and what has been allowed for, especially if no preexisting data on physical conditions are available. In the case of a known deteriorated soil condition, voiding or existing host deformation, the unqualified assumptions made in designing a flexible liner can be inherently flawed unless additional ground treatment is deployed to reinstate the competency of the soil or a grout annulus is introduced between the host pipe and the new liner. It is therefore important to select the right form of lining technology

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that accurately meets the existing ground conditions or in the event of limited soil information, select the technology that is known and can be calculated to withstand all known loadings. The American Water Works Association (AWWA) have categorised linings into four distinct structural classifications in their manual M28: Rehabilitation of Water Mains (2014). Whilst this document relates to water main rehabilitation the structural classification serves as a useful guide to understanding lining strength and is summarised below. Class I Linings Non-structural lining less than 1 mm thick Class II & III Linings Interactive (Composite with the host structure) semi-structural linings Class IV Linings Fully structural and stand-alone requiring no reliance on strength from the existing host structure. For internal as well as external loading.

11.12

Lining Design

As well as the difference between the flexible design against a rigid design, it is also useful to have an understanding of the applicable design standard that best fits the solution that is being sought. In Australia, the tendency is to request that designs are assessed to either AS2566 pt 1, which is the standard for the design of buried flexible pipelines, or under AS5100 (2004), which is the Australian Standard for Bridge Design. Neither of these standards specifically addresses the requirements of an intended lining but some sections relate to loading, durability and material property and cross reference to other standards such as AS1597 (2013), AS3725 (2007), AS3600(2009) and AS3610 (1995). As well as Australian standards, there are International standards that have been specifically written to cover linings inside existing sewers, pipes, culverts and tunnels and the current movement in design is tending to a consult these references as the proposals for larger and more complex rehabilitation systems are being requested. The principle International standards are: The Water Research Council WRc—Sewerage rehabilitation Manual1 United Kingdom.

1

The Water Research Council WRc—Sewerage rehabilitation Manual.

216

P. Marchant

ATV-DVWK-A-127—Static Calculations for the Rehabilitation of Drains and Sewers using Lining and Assembly Procedures2 Germany. ASTM 1216-09—Rehabilitation of Existing Pipelines and Conduits by the Inversion and Curing of a Resin-Impregnated Tube3 USA. ASTM 1743—Standard Practice for Rehabilitation of Existing Pipelines and Conduits by Pulled-in-Place Installation of Cured-in-Place Thermosetting Resin Pipe (CIPP)4 USA. Fascicule 70—Specification of the General Technical Clauses Sewerage Works5 France. VAV P70—Design of Buried Thermoplastic Pipes6 Sweden. In addition to these documented specifications, general application of basic engineering practice under limit state principles can also be developed and more latterly, the use of 2D and 3D Finite Element Analysis is being utilised to derive workable designs. All of these design codes have valid parameters that may and can be assessed in progressing a lining design but consideration must always be subject to the design scope requirements and the duty that the design is required to perform. Similarly, the technologies available to effect either a flexible or a rigid lining are well-documented, so great care needs to be taken in developing a project specification and performance-scope relative to what final outcome is desired. A solution that is required to last 20 years may be significantly different to one that has to sustain 100 years, as is a scope where the risks are fully understood as opposed to one where the Designer/Contractor have to make assessment against limited factual information.

11.13

Conclusion

Mitigating risk and developing a strategic program to asset maintenance relies on a disciplined approach to asset assessment. With factors, such as ageing and deteriorating national and regional infrastructure, increased congestion, increased usage and loading, safety and environmental legislation with public awareness and financial pressure weighing heavily on asset owners, the need to invest in an innovative approach to manage the network is paramount to achieve best dollar value against maintenance spend.

2

ATV-DVWK-A-127—Static Calculations for the Rehabilitation of Drains and Sewers using Lining and Assembly Procedures. 3 ASTM 1216-09—Rehabilitation of Existing Pipelines and Conduits by the Inversion and Curing of a Resin Impregnated Tube. 4 ASTM 1743—Standard Practice for Rehabilitation of Existing Pipelines and Conduits by Pulled-in-Place Installation of Cured in Place Thermosetting Resin Pipe (CIPP). 5 Fascicule 70—Specification of the General Technical Clauses Sewerage Works. 6 VAV P70—Design of Buried Thermoplastic Pipes.

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Culverts, drainage channels and pipes are almost always located under major transport infrastructure, very much out of sight and often out of mind. Culverts are not always given the attention they deserve or require. Financial pressures often result in the reduction of planned maintenance spend. Funds are prioritised on what can be seen rather than what is hidden and quite often as not, spend on subsurface infrastructure becomes reactive because of a failure that could have been prevented if planning and asset recognition had been an integral part of the strategy. Since Culverts typically go unnoticed, there is not always been a sense of urgency to inspect or manage these structures but with the increase of recent high profile failures across the world the need to manage these structures has become apparent. There are several key drivers to achieving a high-quality management program for under surface drainage assets as follows: 1 Knowledge a. Asset Base b. Condition c. Serviceability 2 Works Program a. b. c. d.

Scheduled Inspection Planned Maintenance Access and Cleaning Major works rehabilitation

3 Follow up Works a. Records b. Five and ten-year maintenance programs c. Interaction with surface infrastructure operators Awareness and knowledge of these will give the asset owners the information to make the right decisions in time and on time to get the optimum performance from the asset and to avoid disruption and unplanned expenditure in asset maintenance.

References ASNZ2566 Pt 1. (1998). Buried flexible pipelines part 1 design. The American Water Works Association AWWA M28 Rehabilitation of Water Mains, third Edition (2014). ASNZ5100. (2004). Bridge design. ASNZ1597. (2013). Precast reinforced concrete box culverts. ASNZ3725. (2007). Design for installation of buried concrete pipes. ASNZ3600. (2009). Concrete structures. ASNZ3610. (1995). Formwork for concrete.

Index

A Absorption, 77, 79, 98, 100, 107, 119, 125, 152, 170, 171, 174 Access and cleaning, 217 Activated carbon, 1–3, 115, 116, 118, 164, 166 Adsorption, 3, 9, 19, 21, 25, 70, 77, 79, 100–103, 105, 106, 108–110, 117, 118, 131, 164, 166, 169 Advanced oxidation process, 2 Aerobic degradation, 152 Agriculture and Resource Management Council of Australia and New zealand, 144 Agrobacterium, 7 Alkanes, 124, 163, 169 Alkenes, 124 Ammonium phosphate salt, 123 Anabaena cylindrical, 82 Anodisation, 161–163 Aromatic rings, 124 Asset base, 217 Atomic layer deposition, 168 Australian Drinking Water Guideline, 11 B Bacillus, 7, 85 Biochar, 115, 117–119, 131 Bio-converters, 79 Biofuel, 76, 82–85 Biological activated carbon process, 1 Biological process, 20 Bioremediation, 76, 80 Biosorption, 79 Botryococcus, 79 Brauinii, 77 Buried flexible pipelines, 215 C Carbonyl component, 124

Car wash wastewater, 68, 69, 71, 72 Cast-in-place pipe, 203, 206 Catalyst additives, 123 Ceramic membrane, 65, 67, 69, 70, 72, 95, 98, 99 Ceramic microfiltration, 95, 109 Ceramic ultrafiltration, 63, 70, 98 Chemical coagulation, 1, 65 Chemical disinfection, 135, 137, 138, 145 Chemical oxygen demand, 40, 69, 70, 116 Chemical process, 20, 97 Chemical vapour deposition, 158, 168 Chlamydomonas, 79, 82, 83 Chlamydomonas reihrdtii, 80 Chlorella, 77, 79, 81, 82, 85 Chlorella miniata, 80 Chlorella regularis, 80 Chlorella salina, 80 Chlorella sorokiniana, 80 Chlorella vulgaris, 80, 83, 85 Chlorination, 137, 138, 142, 145 Chlorococcum littorale, 77 Chlorophyta, 77 Class A, 63–65, 71, 72, 137, 140 Coagulation, 2, 3, 9–12, 63, 65–70, 72, 164 Commercial car wash facilities, 64 Cost, 1, 2, 12, 18, 36, 37, 48, 50, 53–55, 64, 75, 76, 84, 97, 117, 118, 137, 152, 153, 155, 165, 168, 187, 190, 194, 198, 204 Culverts, 204, 207, 211, 214, 215, 217 Cyanobaceterium, 76, 82, 84 Cyclic rings, 124 D Decentralized/on-site wastewater treatment, 15, 16, 18, 37–39, 41, 42 Decentralized systems, 16, 36, 41 De-coloration, 152 Degradation of aromatic compounds, 169

© Springer International Publishing AG, part of Springer Nature 2019 M. Pannirselvam et al. (eds.), Water Scarcity and Ways to Reduce the Impact, Applied Environmental Science and Engineering for a Sustainable Future, https://doi.org/10.1007/978-3-319-75199-3

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220 Degradation of organic compounds, 151, 152, 173 Desalination, 136, 137, 187–192, 195 Dibromoacetic acid, 141, 143 Dichloroacetic acid, 141, 143 Differential thermal gravimetry, 120 Direct current, 160 Direct oxidation, 156, 161, 163 Disinfectant By-products (DBPs), 11, 135, 137–144, 146 Dissolved organic carbon, 109 Draining channels, 217 Dye bath, 47, 49, 51, 53, 55 Dye rejection, 49, 51 Dyes, 47–51, 53, 55, 56, 77, 79, 97, 116, 131, 163, 165 E Economic analysis, 54 Electrical energy dose, 9 Electrodeposition, 156–158, 162, 163 Electron capture detection, 140, 145 Electrospray systems, 158 Elevated nutrients, 2 Endocrine disrupting compounds, 2, 98, 137 Environmental protection authority, 64 Ether component, 124 Euglena gracilis krebs, 81 F Fabrication routes, 156, 158 Feasibility studies, 194 Flocculation, 63, 65, 66, 84, 85, 164 FTIR spectroscopy, 123 G Gas chromatography, 140, 145 H Haloacetic acids, 138, 141–144 Haloacetonitriles, 141, 143 Haloketone, 11, 138 Halonitromethanes, 143 High-performance liquid chromatography, 140 Humic acid, 3, 95, 98 Hydrothermal synthesis, 156 I Illicit drugs, 137, 141 Immobilisation on supports, 166 Impact of morphology, 170 Ion chromatography, 140

Index L Lignocellulosic biomass, 118 Lining design, 216 M Mass spectrometry, 140 Mechanical pre-treatments, 152 Membrane bioreactors, 25 Membrane filtration, 18, 47–51, 54, 64, 67, 69, 72, 95, 97, 152, 155, 162 Membrane pore enlargement, 47, 51, 52, 56 Membrane reject, 2 Membrane technologies, 50, 152 Methylene blue, 117, 172, 173 Microalgae, 75–77, 79, 81–85 Micrococcus, 7 Microfiltration (MF), 95, 97 Mitigating risk, 216 Molecular weight cut-off, 51 Monochloroacetic acid, 141, 143 Monoruphidium minutum, 77 N Nammochloris, 77 Nanochloropsis gaditana, 80 Nanofiltration, 47, 49–51, 54, 55 Nanoporous titania materials, 162, 175 Nanotextured materials, 151, 153, 157, 175 National Health and Medical Research Council, 144 Natural organic matter, 65, 97, 98, 140 NEwater, 137 Nitrosamines, 138, 142, 143 O Organic contaminants, 2, 96, 101, 172 Oxyhalides, 138, 142, 143 P Particle size, 51, 96, 98, 101, 105, 106, 108, 110, 119, 157, 158, 171, 172 Pathogens, 16, 18 Per-fluorinated compounds, 137 Permeate flux, 95, 98–100, 108, 110, 152, 167, 168 Personal care products, 23, 24, 26, 27, 137 Pesticides, 2, 96, 137, 163, 169 Petrochemical compounds, 4, 5, 12 Pharmaceuticals, 2, 75, 84, 97, 98, 137, 141 Pharmaceuticals and personal care products, 22, 24 Phormidium, 77, 79

Index Photocatalytic degradation, 95, 101, 107, 110, 170, 174 Photocatalytic materials, 152, 163, 165, 166 Photocatalytic processes, 153, 169 Photo induced processes, 162 Phragmites australis, 23, 24 Physical process, 20, 22 Phytoremediation, 76, 77 Pipes, 36, 136, 199, 201, 204, 207, 209, 211, 215–217 Planned maintenance, 217 Pollution, 16, 27, 47–49, 77, 197 Pore size distribution, 117, 154, 160–162, 166 Pressure line, 201, 202 Primary treatments, 18 Propylene glycol, 23, 26 Proteobacteria, 6, 7 Pseudomonas, 6, 7 Pyrolysis, 115–119, 123–125, 127, 129, 131 R Radio frequency, 160 Ralstonia, 7 Recycled wastewater, 1, 99 Recycled water, 2, 17, 63, 135–137, 140, 143, 146 Rehabilitation of drains and sewers, 216 Reuse of dyes, 53 Reverse osmosis, 2, 49, 50, 63, 70, 72, 77, 190 Reverse osmosis concentrate, 1 Rhodococcus, 7 Roll down, 201, 209 S Salinity, 1, 3, 5–9, 11, 12, 55, 82, 95, 98, 108 Salt aggregation, 51, 52, 56 Salt rejection, 47, 51 Sand filtration, 63, 65, 67–70, 72 Scenedesmus, 77, 79, 80, 82, 83, 85 Scheduled inspection, 217 Seawater reverse osmosis plants, 187 Secondary oxidation, 152 Serviceability, 217 Sliplining, 199, 201, 203 Sludge reactors, 165 Sodium chloride, 49–52 Sodium dodecyl sulphate, 23, 25, 26 Sodium phosphate salt, 123 Sol-gel deposition, 155 Solvothermal synthesis, 156, 157 Sphingopyxis, 7 Spirulina, 77, 79, 81, 83, 84 Sputtering, 154, 156, 160, 162, 163

221 Subsurface flow constructed wetlands, 20 Sugarcane bagasse, 119 Sustainable management, 2 Sustainable waste, 15 Sustainable wastewater treatment systems, 37 T Tamilnadu water supply and drainage board, 188 Textile industry, 47, 48, 50, 51 Titanium dioxide, 98, 151–170, 172, 174 Titanium tetraisopropoxide, 159 Total surface area, 117 Total trihalomethane measurement, 141 Toxicity, 1, 79, 135, 144, 152 Toxicology, 143 Transmembrane Pressure (TMP), 98, 100 Trichloroacetic acid, 141, 143 Trihalomethanes (THMs), 11, 138–146 Trimethyl amine, 23, 26 U Ultrafiltration (UF), 50, 64, 65, 67, 70, 72, 97, 162, 166, 190 United States Environmental Protection Agency, 144 Urban local bodies, 15 Urban water cycle, 136 V Vertical flow system, 21, 22 Volatile organic compounds, 140 W Wastewater, 1–3, 5–10, 12, 15–19, 22, 23, 27, 28, 31, 35–42, 48–51, 53–55, 63–66, 68–70, 72, 75–77, 79, 85, 96–99, 110, 115–117, 136–138, 141, 143, 145, 146, 151, 152, 163, 165, 169, 175 Wastewater management, 15, 35, 37 Wastewater Treatment Plant (WWTP), 54, 75, 98 Water management and treatment, 187 Water networks, 197 Water Research Council, 215 Wet process, 47 Z Zero Liquid Discharge (ZLD), 2, 49, 195 Zeta potential, 101, 105, 106, 108, 110 Zirconia membrane, 99