EnvironmEntal ChEmistry P a n D W d D W rinking ater i rinking ater t • K u D m D isinfection a isinfection r t echniques t echniques Water is our natural heritage, our miracle of life. However, our increasingly technological society has become indifferent to water. Far from being pure, modern drinking water around the world contains many undesirable chemical and bacterial contaminants. The existing techniques employed for the disinfection of water are either energy-intensive or have by-products that are harmful to human health. Drinking Water Disinfection Techniques reviews these processes and explores novel technologies for water disinfection synergistic with existing techniques. The book covers a wide audience and gives a comprehensive review of various physical, chemical, and hybrid techniques commonly used for the disinfection of water as well as newer emerging technologies in terms of their mode of action, scale of operation, efficacy, merits, and demerits. It broadly addresses the issues related to water disinfection in three sections: • Disinfection techniques—chemical, physical, and hybrid (combination)—and their likely scale of operation efficacy • Disinfection by-product as a function of water source and the type of treatment • Emerging and novel techniques, including new work on cavitation, an economical, energy-efficient, and simple alternative to the conventional methods of disinfection Drinking Water Disinfection Techniques effectively combines the chemical, physical, biological, and engineering principles of water disinfection in one text. Discussing both conventional and novel techniques used for disinfection and the economics involved, the book gives a comprehensive review of various physical, chemical, and hybrid techniques used for disinfection to create potable water. K13584 ISBN: 978-1-4398-7740-1 90000 Aniruddha Bhalchandra Pandit 9 781439 877401 and Jyoti Kishen Kumar K13584_Cover_mech.indd 1 11/7/12 10:32 AM D W rinking ater D isinfection t echniques Aniruddha Bhalchandra Pandit and Jyoti Kishen Kumar Boca Raton London New York CRC Press is an imprint of the Taylor & Francis Group, an informa business CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2013 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Version Date: 20121003 International Standard Book Number-13: 978-1-4398-7741-8 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. 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Gopalkrishnan (Amma and Appa) Jyoti Kishen Kumar Contents Foreword ..............................................................................................................xiii Preface .....................................................................................................................xv Acknowledgments .............................................................................................xvii 1. Introduction .....................................................................................................1 1.1 Current Scenario ...................................................................................1 1.2 The Aquatic Environment ...................................................................2 1.3 Health Aspects ......................................................................................3 1.4 History of Disinfection .........................................................................5 1.5 General Aspects of Disinfection .........................................................7 1.6 Water Disinfection Methods................................................................9 1.7 Assessment of Disinfection ...............................................................10 1.8 Quantitative Measurement of Bacterial Growth ............................13 1.9 History of Water Regulations ............................................................17 1.10 Microbiological Standards .................................................................18 Questions ........................................................................................................19 References .......................................................................................................19 2. Chemical Disinfection .................................................................................21 2.1 Introduction .........................................................................................21 2.2 Theory of Chemical Disinfection ......................................................21 2.3 Chlorination .........................................................................................23 2.3.1 Breakpoint Chlorination .......................................................24 2.3.2 How Does Chlorine Kill Microorganisms? ........................25 2.3.3 Factors Affecting Chlorine Disinfection ............................26 2.3.3.1 Concentration and Contact Time .........................27 2.3.4 Methods of Chlorine Treatment ..........................................27 2.3.4.1 Sodium Hypochlorite (Bleach) .............................27 2.3.4.2 Calcium Hypochlorite (Bleaching Powder or Chlorinated Lime) .............................................27 2.3.4.3 Chloramines ............................................................28 2.3.4.4 Chlorine Dioxide ....................................................29 2.4 Other Chemical Methods ...................................................................33 2.4.1 Iodine .......................................................................................33 2.4.2 Silver ........................................................................................36 2.4.3 Potassium Permanganate .....................................................38 2.4.4 Hydrogen Peroxide ................................................................39 2.4.4.1 Production and Application .................................39 2.4.5 Bromine ...................................................................................40 2.4.6 Ferrate ......................................................................................41 vii viii Contents 2.4.7 Water Disinfection by Zero-Valent Iron Nanoparticles ...42 2.5 Chemical Disinfection Treatments Requiring Electricity .............44 2.5.1 Ozone .......................................................................................44 2.6 Coagulation/Flocculation Agents as Pretreatment .......................45 2.7 Disinfection By-Products (DBPs) ......................................................49 2.7.1 Factors Affecting DBP Production ......................................50 2.7.2 Adverse Health Effects of DBPs in Drinking Water .........51 2.7.3 Regulation of DBPs in Drinking Water ..............................52 2.7.4 Examples from Literature .....................................................53 2.7.5 Emerging Contaminants in Disinfection By-Products .....53 2.7.6 Controlling Disinfection By-Products ................................55 2.8 Conclusion ............................................................................................57 Questions ........................................................................................................58 References .......................................................................................................59 3. Physical Disinfection ...................................................................................71 3.1 Introduction .........................................................................................71 3.2 Ultraviolet Radiation ..........................................................................72 3.2.1 Generation of UV ...................................................................72 3.2.2 Mechanism of Bacterial Inactivation ..................................74 3.2.3 Disinfection Efficacy ..............................................................76 3.2.3.1 Bacteria and Virus Inactivation ............................76 3.2.3.2 Protozoa Inactivation .............................................76 3.2.4 Disinfection By-Products of UV Radiation ........................78 3.3 Solar Disinfection ................................................................................80 3.3.1 Mechanisms of Solar Disinfection ......................................80 3.3.2 Factors Affecting Efficacy of Solar Disinfection................82 3.3.3 Inactivation of Microorganisms by Solar Radiation .........83 3.4 Heat Treatment ....................................................................................87 3.5 Filtration Methods ..............................................................................88 3.5.1 Reverse Osmosis ....................................................................88 3.5.2 Microfilters ..............................................................................89 3.5.3 Slow Sand Filter (SSF) ............................................................89 3.5.4 Activated Charcoal Filter ......................................................91 3.6 Distillation ............................................................................................93 3.7 Electrochemical Oxidation ................................................................95 3.8 Water Disinfection by Microwave Heating .....................................96 3.9 Conclusion ............................................................................................97 Questions ........................................................................................................98 References .......................................................................................................99 4. Hybrid Techniques .....................................................................................107 4.1 Introduction .......................................................................................107 4.1.1 What Is the Basis of a Hybrid Method? ............................107 4.1.2 Inactivation Mechanism .....................................................108