Ozonation of Water and Waste Water: A Practical Guide to Understanding Ozone and its Applications, 2nd Edition

Christiane Gottschalk, Judy Ann Libra, and Adrian Saupe Ozonation of Water and Waste Water

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Christiane Gottschalk, Judy Ann Libra, and Adrian Saupe

Ozonation of Water and Waste Water A Practical Guide to Understanding Ozone and its Applications

Second, completely revised and updated edition

The Authors Dr. Christiane Gottschalk ASTEX GmbH Wattstr. 11 13355 Berlin Germany Dr. Judy Ann Libra acatechDeutsche Akademie der Technikwissenschaften Mauerstr. 79 10117 Berlin Germany Dr. Adrian Saupe Projektträger Jülich Zimmerstr. 26–27 10969 Berlin Germany Further Contributors Martin Jekel, Professor of Water Quality Control at the Technical University of Berlin, has been involved in oxidation research since 1976, specializing on ozone/biological activated carbon, microflocculation mechanisms of ozone and advanced oxidation processes for water and wastewaters. He contributed the original manuscript for Chapter 3.3. Anja Kornmüller, Dr.-Ing. in environmental engineering from the Technical University of Berlin. Currently she is the Head of Development Veolia Water Solutions & Technologies Germany, Austria and Switzerland and specialized in advanced oxidation processes in seawater and drinking water. She contributed Section 9.1.2 and 9.3. Dieter Lompe holds a PhD from the Technical University of Berlin. He has worked many years in research and full scale projects with three phase advanced oxidation processes. As Professor at the University of Applied Sciences Bremerhaven (Germany) he is currently working on water technologies and solid waste treatment processes. He coauthored Section 9.1.2.

1. Edition 2000 2. completely revised and updated edition 2010 All books published by Wiley-VCH are carefully produced. Nevertheless, authors, editors, and publisher do not warrant the information contained in these books, including this book, to be free of errors. Readers are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate. Library of Congress Card No.: applied for British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. Bibliographic information published by the Deutsche Nationalbibliothek The Deutsche Nationalbibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data are available on the Internet at . © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim All rights reserved (including those of translation into other languages). No part of this book may be reproduced in any form – by photoprinting, microfilm, or any other means – nor transmitted or translated into a machine language without written permission from the publishers. Registered names, trademarks, etc. used in this book, even when not specifically marked as such, are not to be considered unprotected by law. Typesetting Toppan Best-set Premedia Limited Printing Strauss GmbH, Mörlenbach Binding Litges & Dopf GmbH, Heppenheim Cover Design Grafik Design Adam, Weinheim Printed in the Federal Republic of Germany Printed on acid-free paper ISBN: 978-3-527-31962-6

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Contents Preface to the Second Edition XIII Preface to the First Edition XV Introduction 1 Part I Ozone in Overview 1 1.1 1.2 1.2.1 1.2.2 1.2.3 1.3 1.4

Toxicology 5 Background 5 Ozone in Gas 7 Inhalation 7 Skin Contact 7 Eye Contact 7 Ozone in Liquid 8 By-products 9 References 11

2 2.1 2.1.1 2.1.1.1 2.1.1.2 2.1.1.3 2.1.1.4 2.1.2 2.2 2.2.1 2.2.2 2.2.3

Reaction Mechanism 13 Ozonation 13 Indirect Reaction 13 Initiation Step 14 Radical Chain Reaction 15 Termination Step 15 Overall Reaction 16 Direct Reaction 17 Advanced Oxidation Processes (AOP) 20 Ozone/Hydrogen Peroxide O3/H2O2 20 Ozone/UV-Radiation O3/UV 21 Hydrogen Peroxide/UV-Radiation UV/H2O2 22 References 24

Ozonation of Water and Waste Water. 2nd Ed. Ch. Gottschalk, J.A. Libra, and A. Saupe Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN: 978-3-527-31962-6

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Contents

3 3.1 3.2 3.2.1 3.2.2 3.3 3.3.1 3.3.2 3.3.3 3.3.3.1 3.3.3.2 3.3.4 3.4 3.4.1 3.4.2 3.4.3 3.4.3.1 3.4.3.2 3.4.3.3 3.4.4 3.5

Ozone Applications 27 Historical Development 27 Overview of Ozone Applications 31 Ozone in the Gas Phase 32 Ozone in the Liquid Phase 34 Ozone in Drinking-Water Treatment 36 Disinfection 38 Oxidation of Inorganic Compounds 40 Oxidation of Organic Compounds 42 Natural Organic Matter (NOM) 42 Organic Micropollutants 43 Particle-Removal Processes 44 Ozonation in Waste-Water Treatment 46 Disinfection 47 Oxidation of Inorganic Compounds 48 Oxidation of Organic Compounds 49 Landfill Leachates – Partial Mineralization 52 Textile Waste Waters – Color Removal and Partial Mineralization Other Applications 54 Particle-Removal Processes 55 Economical Aspects of Ozonation 56 References 59 Part II Ozone Applied

4 4.1 4.2 4.2.1 4.2.2 4.2.3 4.2.3.1 4.2.3.2 4.2.4 4.2.5 4.2.6 4.3 4.3.1 4.3.1.1 4.3.1.2 4.3.2 4.3.3 4.3.3.1 4.3.3.2 4.3.3.3

Experimental Design 69 Experimental Design Process 70 Experimental Design Steps 73 Define Goals 73 Define System 74 Select Analytical Methods and Methods of Data Evaluation Ozone 83 Target Compound M 83 Determine Experimental Procedure 85 Evaluate Data 88 Assess Results 89 Reactor Design 94 Reactor Types 94 Operating Mode 94 Mixing 95 Comparison of Reactor Types 97 Design of Chemical Oxidation Reactors 100 Reaction System 102 Ancillary Systems 103 Process Integration 103

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Contents

4.3.3.4 4.3.3.5 4.4 4.4.1 4.5

Controllability 104 Site Integration 104 Checklists for Experimental Design 104 Checklists for Each Experimental Design Step Ozone Data Sheet 108 References 111

5 5.1 5.1.1 5.1.1.1 5.1.1.2 5.1.2 5.1.2.1 5.1.2.2 5.2 5.2.1 5.2.1.1 5.2.1.2 5.2.1.3 5.2.1.4

Experimental Equipment and Analytical Methods 113 Materials in Contact with Ozone 113 Materials in Pilot- or Full-Scale Applications 116 Reactors 116 Piping 116 Materials in Lab-Scale Experiments 117 Reactors 117 Piping 118 Ozone Generation 118 Electrical Discharge Ozone Generators (EDOGs) 120 Chemistry 121 Engineering and Operation 123 Type of Feed Gas and its Preparation 125 Ozone Concentration, Production Capacity and Specific Energy Consumption 126 Use of EDOGs in Laboratory Experiments 126 Electrolytic Ozone Generators (ELOGs) 127 Use of ELOGs in Laboratory Experiments 130 Reactors Used for Ozonation 130 Overview of Hydrodynamic Behavior and Mass Transfer 131 Directly Gassed Reactors 135 Bubble Columns and Similar Reactors 135 Stirred-Tank Reactors 136 Indirectly and Nongassed Reactors 138 Tube Reactors 138 Membrane Reactors 139 Types of Gas Contactors 141 Mode of Operation 144 Experimental Procedure 145 Batch Experiments 145 Continuous-Flow Experiments 146 Process Combinations 146 Ozone Measurement 147 Methods 147 Iodometric Method (Gas and Liquid) 147 UV Absorption (Gas and Liquid) 147 Visible-Light Absorption (Gas and Liquid) 149 Indigo Method (Liquid) 149

5.2.1.5 5.2.2 5.2.2.1 5.3 5.3.1 5.3.2 5.3.2.1 5.3.2.2 5.3.3 5.3.3.1 5.3.3.2 5.3.4 5.3.5 5.3.6 5.3.6.1 5.3.6.2 5.3.6.3 5.4 5.4.1 5.4.1.1 5.4.1.2 5.4.1.3 5.4.1.4

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Contents

5.4.1.5 5.4.1.6 5.4.1.7 5.4.2 5.5 5.5.1 5.5.2 5.6

N,N-diethyl-1,4 Phenylenediammonium – DPD (Liquid) Chemiluminescence – CL (Liquid) 150 Membrane Ozone Electrode (Liquid) 151 Practical Aspects of Ozone Measurement 152 Safety Aspects 152 Vent Ozone Gas Destruction 152 Ambient Air Ozone Monitoring 154 Common Questions, Problems and Pitfalls 154 References 159

6 6.1 6.1.1 6.1.2 6.1.3 6.1.4 6.2 6.2.1 6.2.1.1 6.2.1.2

Mass Transfer 163 Theory of Mass Transfer 163 Mass Transfer in One Phase 164 Mass Transfer between Two Phases 166 Equilibrium Concentration for Ozone 167 Two-Film Theory 172 Parameters That Influence Mass Transfer 173 Mass Transfer with Simultaneous Chemical Reactions 175 Interdependence of Mass Transfer and Chemical Reaction 176 Effect of Kinetic Regime on Determination of Mass-Transfer Coefficients 180 Predicting the Mass-Transfer Coefficient 182 Theta Factor – Correction Factor for Temperature 183 Alpha Factor – Correction Factor for Water Composition 183 Influence of Water Constituents on Mass Transfer 184 Change in Bubble Coalescence 184 Changes in Surface Tension 185 Determination of Mass-Transfer Coefficients 186 Choice of Direct or Indirect Determination of kLa(O3) 187 General Experimental Considerations and Evaluation Methods 188 Equilibrium Concentration c*L 189 Nonsteady-State Methods Without Mass-Transfer Enhancement 191 Batch Model 191 Experimental Procedure 192 Continuous-Flow Model 192 Experimental Procedure 193 Steady-State Methods Without Mass-Transfer Enhancement 193 Semibatch and Continuous-Flow Models 194 Experimental Procedure 194 Simultaneous Determination of kLa and rL 195 Methods with Mass-Transfer Enhancement 196 Experimental Procedure 197 Problems Inherent to the Determination of Mass-Transfer Coefficients 197

6.2.2 6.2.2.1 6.2.2.2 6.2.3 6.2.3.1 6.2.3.2 6.3 6.3.1 6.3.2 6.3.2.1 6.3.3 6.3.3.1 6.3.3.2 6.3.3.3 6.3.3.4 6.3.4 6.3.4.1 6.3.4.2 6.3.4.3 6.3.5 6.3.5.1 6.3.6

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Contents

6.3.6.1 Nonsteady-State Method 197 6.3.6.2 Steady-State Method 199 References 200 7 7.1 7.1.1 7.1.1.1 7.1.1.2 7.1.1.3 7.2 7.2.1 7.3 7.3.1 7.3.1.1 7.3.1.2 7.3.2 7.3.3 7.3.4 7.3.5 7.3.6

8 8.1 8.1.1 8.1.2 8.1.3 8.1.3.1 8.1.3.2 8.1.3.3 8.1.4 8.2 8.2.1 8.2.2 8.2.2.1 8.2.2.2 8.2.2.3 8.2.2.4

Reaction Kinetics 205 Reaction Order 205 Experimental Procedure to Determine the Reaction Order n 209 Half-Life Method 210 Initial Reaction Rate Method 210 Trial and Error 210 Reaction Rate Constants 211 Determination of Rate Constants 213 Parameters That Influence the Reaction Rate 215 Concentration of Oxidants 216 Direct Reactions 216 Indirect or Hydroxyl Radical Reactions 216 Temperature Dependency 217 Influence of pH 217 Influence of Inorganic Carbon 218 Influence of Inorganic Salts 219 Influence of Organic Carbon on the Radical Chain-Reaction Mechanism 220 References 221

Modeling of Ozonation Processes 225 Ozone Modeling 228 General Description of the Ozone Modeling Problem 228 Chemical Model of Ozonation 231 Mathematical Model of Ozonation 232 Mass Balances 232 Rate Equations 234 Solving the Model 235 Summary 236 Modeling of Drinking-Water Oxidation 237 Chemical and Mathematical Models 237 Methods to Determine the Hydroxyl-Radical Concentration 240 Indirect Measurement 241 Complete Radical-Chain-Reaction Mechanism 244 Semiempirical Method Based on Observable Parameters 245 Semiempirical Method Based on Observed Hydroxyl Radical Initiating Rate 246 8.2.2.5 Empirical Selectivity for Scavengers 247 8.2.2.6 Summary of Chemical and Mathematical Models for Drinking Water 249

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8.2.3 8.3 8.3.1 8.3.2 8.3.3 8.4

Models Including Physical Processes 249 Modeling of Waste-Water Oxidation 250 Chemical and Mathematical Models 251 Empirical Models 260 Summary 261 Final Comments on Modeling 261 References 263

9 9.1 9.1.1 9.1.1.1 9.1.1.2 9.1.1.3 9.1.2 9.1.2.1 9.1.2.2 9.1.2.3 9.2 9.2.1 9.2.1.1 9.2.1.2 9.2.2 9.2.3 9.2.3.1 9.2.3.2 9.2.3.3 9.2.3.4 9.2.3.5 9.2.3.6 9.2.4 9.2.4.1 9.2.4.2 9.2.4.3 9.2.4.4 9.3 9.3.1 9.3.2 9.3.2.1 9.3.2.2 9.3.3 9.3.3.1 9.3.3.2 9.3.3.3 9.3.3.4

Application of Ozone in Combined Processes 267 Advanced Oxidation Processes 268 Chemical AOPs 269 Principles and Goals 269 Existing Processes 269 Experimental Design 272 Catalytic Ozonation 273 Principles and Goals 273 Existing Processes and Current Research 275 Experimental Design 280 Three-Phase Systems 281 Principles and Goals 282 Gas / Water / Solvent Systems 283 Gas / Water / Solid Systems 284 Mass Transfer in Three-Phase Systems 284 Existing Processes and Current Research 287 Gas / Water / Solvent Systems 287 Gas / Water / Solid Systems 290 Change in the Solids 290 Change in Compounds Adsorbed on the Solids 292 Soil Ozonation 292 Regeneration of Adsorbents 293 Experimental Design 294 Define System 294 Select Analytical Methods 295 Determine Experimental Procedure 296 Evaluate Data and Assess Results 296 Chemical-Biological Processes (CBP) 297 Principles and Goals 297 Existing Processes and Current Research 301 Drinking-Water Applications 302 Waste-Water Applications 304 Experimental Design 314 Define System 315 Select Analytical Methods 318 Determine Experimental Procedure 320 Evaluate Data 323

Contents

9.3.3.5 9.4 9.4.1 9.4.2 9.4.3 9.4.4 9.4.4.1 9.4.4.2 9.4.4.3 9.4.4.4

Assess Results 324 Applications in the Semiconductor Industry 327 Production Sequence 327 Principles and Goals 329 Existing Processes for Cleaning and Oxidation 330 Process and / or Experimental Design 333 Define System 333 Select Analytical Methods 333 Determine Procedure 333 Evaluate Data and Assess Results 334 References 334 Glossary of Terms 345 Index 353

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Preface to the Second Edition The first edition of this Practical Guide to Understanding Ozone and its Application was published in the year 2000 and was well received. It was even translated into Chinese in 2004. Since then much work on ozone has been carried out and a comprehensive new edition was needed. Changes in regulations for disinfection by-products in various parts of the world have driven the use of ozone in various water applications. Concern over micropollutants in wastewater effluents has spurred interest in its use in municipal waste water treatment as a polishing treatment before discharge. An important goal in updating the book was to summarize these recent developments. However, it remains focused on the basics necessary for someone getting started in ozone, mainly for the student, researcher and for people who are involved in process development and design. The structure of the book – Part One: Ozone in Overview and Part Two: Ozone Applied – was maintained. Part One was expanded to cover disinfection byproducts and provide an overview of the wider application areas of ozone as well as a short history of its use before reviewing the specific applications in water. In Part Two the practical aspects have been expanded and the differences in wastewater and drinking-water applications are dealt with more explicitly. Chapter 4 reviews experimental and reactor design concepts for those that need a quick refresher of the material learned in basic classes, while Chapters 6 and 8 build a firm basis to model the whole process. Chapter 6 has been expanded to include current mass-transfer theories and in Chapter 8 the description of modeling approaches deals explicitly with the differences in waste-water and drinking-water applications. The update adds some “missing elements” that we have identified over the years of using the book. We hope the additions will increase the “practicality” of the guide for others as well. Structure of the Book

The book consists of two parts: Part One: Ozone in Overview and Part Two: Ozone Applied. The first part is intended to provide a general background on ozonation, briefly reviewing the toxicology of ozone, its reaction mechanisms, and full-scale applications of ozonation. This provides motivation for experimental activity, Ozonation of Water and Waste Water. 2nd Ed. Ch. Gottschalk, J.A. Libra, and A. Saupe Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN: 978-3-527-31962-6

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Preface to the Second Edition

applying ozone in the laboratory. The second part of the book tries to offer information on just how to go about it. The design of experiments and required equipment as well as analytical methods and data evaluation are first discussed. Then, the theoretical background needed to carry out these activities is explored. The goal here is to include the basics necessary for building a solid foundation, and to reference secondary sources, with which the reader can delve deeper into ozonation specifics. Part Two is rounded out with a discussion of applications that use ozone in combination with other treatment processes. Acknowledgment

The authors would like to thank Kerstin, Rolf, Alan, Malte and Maarten for the patience and time they gave us to finish the second edition of this book. Chris Gottschalk, Judy Libra, and Adrian Saupe March 2009

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Preface to the First Edition The ozonation of compounds in water is a complex process. The mechanisms are very complicated, the parameters are many, but the possibilities of developing cost-effective treatment schemes for drinking water and waste water are large. To take advantage of this potential, it is important to know which parameters contribute to the process, which are important, and how they affect the process. Because ozonation is so system dependent, most full-scale applications are first tried out bench-scale. That means designers and manufacturers of treatment systems, researchers, as well as potential industrial operators of ozonation must know not only the fundamentals of the mechanisms of ozonation, but also how to set up experiments so that the results can be interpreted, extrapolated, and applied. Most books available today concentrate on either drinking-water or waste-water treatment, seldom dealing with both or explaining the essential differences. And only rare exceptions deal with the how-to of ozone experiments. This guide fills the gap. It contains the cumulative knowledge gathered by the authors as researchers, teachers and ozone-system developers on experimental design, execution, interpretation and application. Drawing on experience gained from hours spent on laboratory research with drinking and waste waters, literature study, intensive discussion with leading experts, perplexed reflection and deep thought, the book offers practical help to avoid common pitfalls and unnecessary work. This book is aimed at professionals in industry and research currently using ozonation who want to optimize their system, as well as students beginning work with ozonation. Much literature exists today about ozonation, but its practical use for beginners is limited by its specialization, and for the advanced by its magnitude and diversity. The practical guide presents an overview of current theories and results from the specialized literature in short concise text, tables and figures accompanied with references to important secondary literature. It contains just enough information for beginners to start with, but goes rapidly to the detailed information that advanced readers need.

Ozonation of Water and Waste Water. 2nd Ed. Ch. Gottschalk, J.A. Libra, and A. Saupe Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN: 978-3-527-31962-6

1

Introduction Being poised on the edge of the third millennium in Berlin, the city of Siemens who constructed the first ozone generator almost 150 years ago, and writing a book on ozone applications in water can make one philosophical. Especially when one has been confronted with the puzzlement of most acquaintances about why anyone deliberately produces ozone and what it has to do with water. These two aspects of this book: ozone and water need some clarification. Ozone can be present as a gas or dissolved in a liquid. The media reports almost exclusively on gaseous ozone. For example, that the beneficial ozone layer in our atmosphere is being depleted, allowing more damaging UV-radiation from the sun to reach us on earth. On the other hand, announcements in the media warn about too high ozone concentrations in our air on sunny days, causing damage to human health and the environment. That ozone can have beneficial and detrimental effects can be confusing if it is not made clear that the effect is dependent on the location of the ozone. Direct exposure is always detrimental. The other aspect is water itself. A survey has shown that pure water contains only 98.1% H2O, at least that is the common perception [1]. Although water pollution has not caused such an extreme change in the composition of our water resources, we have allowed many substances to enter the natural water cycle with detrimental effects on human health and the natural environment. The result is additional treatment processes are often necessary to prepare drinking water for every day use. And processes are necessary for waste-water treatment and groundwater remediation to prevent even larger contamination. Here, ozone comes into play. It is capable of oxidizing a large number of pollutants in an environmentally sound way, since normally no harmful end- or by-products are formed nor are secondary wastes produced. Unfortunately, we cannot make use of the ozone gas sometimes present in unacceptably high concentrations in our breathing air (e.g., >240 µg m−3), but we have to produce it in ozone generators from air or from pure oxygen using much energy, to reach concentrations higher by a factor of a million (240 g m−3). The fact that almost 150 years after the production of the first ozone generator a book is still necessary on how to experiment with one, shows that ozonation is a complex subject. Some very good reference books and articles exist that explain the fundamentals of ozonation, the chemical reactions, the effect of some Ozonation of Water and Waste Water. 2nd Ed. Ch. Gottschalk, J.A. Libra, and A. Saupe Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN: 978-3-527-31962-6

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Introduction

parameters. However, most work concentrates on either drinking-water treatment or waste-water treatment, seldom dealing with both, reflecting our personal experience that these are two separate “worlds”. Since ozone applications in production processes are growing, even more people from various disciplines need access to information on ozone and how to make use of the results from the various applications. We have tried to bridge this information gap with this book, building on our diverse backgrounds in drinking-, waste- and process-water treatment. Another area rarely dealt with in previous literature is the “how-to” of ozone experiments. This information is usually hard-earned by doctoral candidates and laboratory staff, and either not considered as appropriate information for a scientific treatise or considered as proprietary information that belongs to expertise. This lack of information has motivated us to write a book that contains not only fundamental information about the toxicology of ozone, its reaction mechanisms, and full-scale applications of ozonation (Part One: Ozone in Overview), but also information on how to set up experiments so that they produce results that can be interpreted and extrapolated (Part Two: Ozone Applied). The experimenter is provided with tools to improve his or her results and interpret results found in the literature. The required theoretical foundation is laid at the beginning of each chapter in Part Two, compact and tailored to ozone, followed by practical aspects. References are made to important literature sources to help direct the reader wishing for more in-depth information. A discussion of applications combining ozone with other processes illustrates how the oxidizing potential of ozone can be utilized.

Reference 1 Malt, B.C. (1994) Water is not H2O. Cognitive Psychology, 27 (1), 41–70.

Part I Ozone in Overview

Ozonation of Water and Waste Water. 2nd Ed. Ch. Gottschalk, J.A. Libra, and A. Saupe Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ISBN: 978-3-527-31962-6

5

1 Toxicology Toxicology examines the adverse effects of substances on living organisms. The effect on humans has been traditionally the subject of this study. The field of ecotoxicology has been developed to study the wider effects of substances on an ecosystem, not only on individual organisms, but also on the interactions between the elements in ecosystems. Both areas are important when evaluating the toxicology of ozonation applications. The species affected by a substance depends on the application – studies on drinking water concentrate on human toxicology and waste water on aquatic ecotoxicology. This chapter will give a short overview of the toxicology of ozone. The types of toxicity and study subjects are briefly reviewed (Section 1.1), before the toxicological effects of exposure to ozone are presented. When talking about the effects of ozone, one has to differentiate between the routes of exposure and the type of compound being examined. The exposure can take place with:

• • •

ozone in gas (Section 1.2); ozone in liquid (Section 1.3); and by-products formed by ozone reactions (Section 1.4).

1.1 Background

In the description of the effect of a substance on an organism, consideration of the length of exposure necessary for the effect is essential. Toxicity is usually differentiated into three types according to the exposure. Acute toxicity describes a fast harmful effect after only a short-term exposure (