1、Water Quality in Distribution Systems Manual of Water Supply Practices M68 Ideal crop marks Ideal crop marks 30068 (10/17) IW www.awwa.org Dedicated to the worlds most important resource, AWWA sets the standard for water knowledge, management, and informed public policy. AWWA members provide solutio
2、ns to improve public health, protect the environment, strengthen the economy, and enhance our quality of life. D istribution systems represent the last protective barrier available to water systems to maintain safe and high-quality water. This manual provides a “first stop” for common distribution s
3、ystem water quality challenges. M68 offers practical guidance and best management practices for maintaining and improving distribution system water quality. It will help drinking water utilities and professionals understand the factors that affect water quality, ways to address them and best practic
4、es for optimizing distribution system water quality. Each chapter within the manual focuses on a unique distribution challenge, how to characterize and respond to such challenge, and recommend best practices to address ongoing issues and optimization strategies. The manual covers a variety of topics
5、 such as corrosion, taste and odor concerns, microbiology, capacity and water age, and more. M68 includes numerous case studies to better show the applications discussed. The manual also provides a larger resources section where readers can find places for additional expertise. M68 M68 Water Quality
6、 in Distribution SystemsWater Quality in Distribution Systems M68 Manual of Water Supply PracticesAmerican Water Works Association 6666 West Quincy Avenue Denver, CO 80235-3098 awwa.org Printed in the United States of America ISBN 978-1-62576-226-9 eISBN-13 978-1-61300-423-4 Manual of Water Supply P
7、racticesM68 Water Quality in Distribution Systems Copyright 2017 American Water Works Association All rights reserved. No part of this publication may be reproduced or transmitt ed in any form or by any means, electronic or mechanical, including photocopy, recording, or any information or retrieval
8、system, except in the form of brief excerpts or quotations for review purposes, without the writt en permission of the publisher. Disclaimer The authors, contributors, editors, and publisher do not assume responsibility for the validity of the content or any consequences of its use. In no event will
9、 AWWA be liable for direct, indirect, special, incidental, or consequential damages arising out of the use of information presented in this book. In particular, AWWA will not be responsible for any costs, including, but not limited to, those incurred as a result of lost revenue. In no event shall AW
10、WAs liability exceed the amount paid for the purchase of this book. If you nd errors in this manual, please email booksawwa.org. Possible errata will be posted at www.awwa.org/resources-tools/resource.development.groups/manuals-program.aspx. Senior Managing Editor/Project Manager: Melissa Valentine
11、Cover art: Melanie Yamamoto Production: Janice Benight Manuals Specialist: Sue Bach Library of Congress Cataloging-in-Publication Data Names: Smith, Kira S., author. | Slabaugh, Rebecca, author. | American WaterWorks Association, issuing body. Title: Water quality in distribution systems / by Kira S
12、. Smith, RebeccaSlabaugh. Other titles: AWWA manual ; M68. Description: First edition. | Denver, CO : American Water Works Association,2017 | Series: AWWA ; M68 | Includes bibliographical references andindex. Identi ers: LCCN 2017028391 | ISBN 9781625762269 Subjects: LCSH: Water quality management.
13、| Water-Distribution. Classi cation: LCC TD365 .S62 2017 | DDC 628.1/44-dc23 LC record available at htt ps:/lccn.loc.gov/2017028391AWWA Manual M68 iii Contents List of Figures, vii List of Tables, xi Acknowledgments, xv Chapter 1 Introduction .1 Getting StartedHow to Identify a Problem or Challenge,
14、 2 Summary of Standards and Regulations, 6 References, 11 Chapter 2 Capacity and Water Age .13 Determining Capacity, 14 Determining Water Age, 21 Ways to Balance Capacity and Water Age, 24 Best Practices for Optimizing Distribution System Capacity and Water Age, 35 References, 37 Chapter 3 Understan
15、ding and Managing Biofi lm, Coliform Occurrence, and the Microbial Community .39 Microbial Growth Challenges in the Distribution System, 40 Summary of Regulatory Frameworks Applicable to Microbes in Distribution Systems, 50 Microbial Occurrence Pathways, 52 Microbial Indicators of Water Quality, 54
16、Techniques for Characterizing Microbial Communities, 60 Contributing Factors, Mitigation, and Corrective Actions for Microbial Occurrence Problems, 62 Best Practices to Mitigate and Manage Microbial Growth, 69 References, 71 Chapter 4 Infrastructure Integrity and Water Quality81 Factors That Affect
17、Physical Integrity, 82 Factors That Affect Water Quality, 84 Water Quality Indicators, 86 Addressing Water Quality Challenges, 86 Best Practices, 88 References, 97 Chapter 5 Taste, Odor, and Appearance 101 Aesthetic Water Quality Goals, 103 General Identification and Monitoring of Water Quality Aest
18、hetics in Distribution Systems, 103 Taste and Odor, 110 Appearance, 125 Summary and Recommendations, 131 References, 133iv AWWA Manual M68 Chapter 6 Nitrification 151 Disclaimer, 151 Nitrification, 152 Causes of Nitrification in Distribution Systems, 155 Examples of Nitrification, 163 Responses to C
19、ontrol Nitrification, 167 Nitrification Monitoring and Control Plan, 173 Nitrification Prevention, 180 Case Study, 185 Conclusions and Recommendations, 186 References, 188 Chapter 7 Corrosion Control .195 Water Quality Impacts, 196 Factors Affecting Corrosion-Related Water Quality, 201 Water Quality
20、 Monitoring, 210 Corrosion Control Methods, 216 Best Practices for Corrosion Control Through Distribution System Design, Operation, and Maintenance, 218 Summary, 225 References, 227 Chapter 8 Disinfectants and Disinfection By-products .233 Regulations, 234 Disinfectants, 239 Control Strategies, 248
21、Best Practices, 256 Summary, 258 References, 260 Chapter 9 Management of Low Pressure 267 Pressure Standards and Goals, 268 Causes of Depressurization and Intrusion, 269 Public Health Impact of Depressurization-Related Water Quality Problems 271 Tracking Depressurization-Related Water Quality Challe
22、nges, 274 Preventing and Managing Low Pressure, 283 Distribution System O transmission electron micrograph (bar, 0.1 m), 154 6-2 Simplified Nitrosomonas europaea central metabolism, 154 6-3 US minimum total chlorine residuals in distribution systems (not at entry points to the distribution system),
23、by state, for Subpart H Surface Water Treatment Rule systems. Information is based on a review of existing states rules and regulations as of January 2015, 158 Figuresviii AWWA Manual M68 6-4 Monochloramine decay as a function of Cl/N molar ratio. Cl/N = 0.5 ( , ) Cl/N = 0.6 (, ), and Cl/N = 0.7 ( ,
24、). Open symbols are for pH 7.5 and filled symbols are for pH 6.5. NH 2 Cl = 0.05 mM, C T, CO3= 4 mM, = 0.1 M, temperature = 25C. 0.05 mM NH 2 Cl = 3.55 mg Cl 2 /L, 160 6-5 Effect of pH on monochloramine decay at 25C. 0.05 mM NH 2 Cl = 3.55 mg Cl 2 /L, 161 6-6 Effect of total carbonate on monochloram
25、ine decay at (A) pH 6.6, (B) pH 7.6, and (C) pH 8.3. Cl/N = 0.7 mol/mol, = 0.1 M, temperature = 25C. 0.05 mM NH 2 Cl = 3.55 mg Cl 2 /L, 162 6-7 Effect of temperature on monochloramine decay. Cl/N = 0.7 mol/mol, pH = 7.5, C T, CO3 = 10 mM, = 0.1 M. 0.05 mM NH 2 Cl = 3.55 mg Cl 2 /L, 163 6-8 Effect of
26、 03 mg/L bromide ion on monochloramine stability at pH 7.5. Cl/N = 0.7 mol/mol, C T, CO3 = 4 mM, = 0.1 M, temperature = 25C. 0.05 mM NH 2 Cl = 3.55 mg Cl 2 /L, 163 6-9 Theoretical water quality changes during a nitrification event, 165 610 Example of complete nitrification in a Massachusetts Water R
27、esources Authority distribution system, 166 6-11 Example of storage tank breakpoint chlorination procedure, 169 6-12 Impact of tank draining and disinfecting on nitrification, 170 6-13 Theoretical breakpoint curve, 171 614 Free chlorine period survey results, 172 6-15 Example of system-wide breakpoi
28、nt chlorination protocol, 172 6-16 Total chlorine residual as a function of time at various distribution system sampling locations, 176 6-17 Changes in chlorine concentrations with water age in a distribution system, 177 6-18 Common water system actions to control nitrification from a 2004 survey, 1
29、80 6-19 Example of storage tank stratification occurrence and assessment, 183 6-20 Effectiveness of booster chloramination in reducing nitrite formation at Key West Utility, 185 7-1 Red water sample from a US water distribution system, 200 7-2 Oxidation-reduction potential of common oxidants at vari
30、ous dosages, 206 7-3 Pourbaix diagram for lead, 207 7-4 Pourbaix diagram for copper, 207 7-5 Pourbaix diagram for iron at 25C and 4.8 mg/L dissolved inorganic carbon, 208 7-6 Correlations (R 2values) between trace inorganic compound release in two water systems distribution systems, 209 7-7 Calcium
31、carbonate precipitation in a distribution main, 213 7-8 Mini pipe loops, 222 7-9 Metal plates inside and stacked in open test chambers, 223 7-10 Process control charts for historical disinfection data at two Revised Total Coli- form Rule sampling sites, 224ix AWWA Manual M68 7-11 Example of pipe bef
32、ore and after cleaning and lining with cementmortar, 226 7-12 Steel pipe lined with epoxy, 226 8-1 Main pathways involved in the formation of ozone by-products, 244 8-2 Example of the correlations between water age, trihalomethanes, and disinfectant residual in distribution systems, 249 8-3 Example
33、of correlations between water age, haloacetic acids, and disinfectant residual in distribution systems, 250 8-4 Effect of cycling spray nozzle aeration (on/off) on trihalomethane level in a 0.5-mil gal clearwell in Madison, North Carolina, 252 9-1 Example of a pressure transient, 270 9-2 Water syste
34、m power outages per year, 272 9-3 Examples of potential intrusion sites: (a) broken main near sewer pipe, (b) broken main near storm pipe, and (c) flooded meter vault, 272 9-4 Example field installations of pressure monitors in distribution systems, 276 9-5 Example output of the spreadsheet program
35、for pressure monitoring, 278 9-6 Pressure transient control and management in (a) large zones and (b) small zones of 36 surveyed systems, 287 9-7 Location of boil-water advisories in the United States, 291 9-8 Modeled minimum pressure in an Illinois water system during a power outage at the primary
36、pump station, 296 9-9 Backflows and low pressure event caused by main break: (a) broken main, back- flow locations, and modeled negative pressures; (b) pressure drop at the two optimized pressure monitoring locations; and (c) water usage increase during the main break, 297 10-1 Absolute, atmospheric
37、, gauge, and vacuum pressures, 308 10-2 Example of a barometric loop, 309 10-3 Diagram of the Venturi effect, 310 11-1 Contamination warning indicators, 325 11-2 Steps in the ANSI/AWWA Standard J100 risk assessment process, 332 A-1 Importance of heterotrophic plate count method (plate count agar ver
38、sus R2A), 341 D-1 Nitrification assessment flowchart, 369 D-2 Total chlorine residual as a function of time at various distribution system sampling locations, 371This page intentionally blank.xi AWWA Manual M51 1-1 M68 chapters and their focus, 2 1-2 Chapters on microbial activity and disinfectant r
39、esidual challenges, 5 1-3 Chapters on disinfection by-products challenges, 5 1-4 Chapters on internal corrosion challenges, 5 1-5 Customer complaint issues, 6 1-6 Summary of USEPA distribution system regulatory requirements and monitoring, 7 1-7 Summary of Health Canada distribution system guideline
40、s and monitoring, 9 2-1 Typical pipe capacity design criteria, 16 2-2 Example diurnal pattern and equalizing storage volume calculation, 19 2-3 Water quality evaluation criteria for balancing system capacity and water age, 36 3-1 Recognized and potential enteric and water-based microbial pathogens t
41、o manage community drinking water risks, 47 3-2 US Safe Drinking Water Act regulations related to microorganisms in the distribution system, 51 3-3 Microbial parameters and use as indicators, 56 3-4 Best practices to control microbial growth, 70 4-1 Pipeline life expectancy benchmarks, 82 4-2 Leak d
42、etection methods, 90 4-3 Recommended leak detection method based on type of pipe, 90 4-4 Examples of wall thickness measurement methods, 91 4-5 Common rehabilitation methods, 94 4-6 Best practices to mitigate aging infrastructure, 95 5-1 Regulations for drinking water aesthetics for the World Health
43、 Organiza- tion, European Union, Canada, and the United States, 104 5-2 Odor threshold and descriptors for volatile inorganic and organic sulfur compounds, 111 5-3 Compounds that cause chlorinous, ozonous, and medicinal tastes and odors in water, 113 5-4 Odorous chemicals that leach from polymer pipes and have or may have regulatory limits, 115 5-5 Taste characteristics and regulations of major components in waters, 123 5-6 Common descriptions and potential sources of discolored water events, 128 5-7 Recommended practices to address taste, odor, and appearance issues, 131 Tables
