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Waste water treatment_technologies_handbook

  1. 1. HANDBOOK OF WATER ANDWASTEWATER TREATMENTTECHNOLOGIESNicholas P. Cheremisinoff, Ph.D.N&P LimitedP- - E I N E M A N NBoston Oxford Auckland Johannesburg Melbourne New Delhi
  2. 2. Copyright 0 2002 by Butterworth-Heinemann -a( A member of the Reed Elsevier group All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher.@ Recognizing the importance of preserving what has been written, Butterworth-Heinemann prints its books on acid-free paper whenever possible. ISBN: 0-7506-7498-9 The publisher offers special discounts on bulk orders of this book. For information, please contact: Manager of Special Sales Butterwofih-Heinemann 225 Wildwood Avenue WObUm, MA 01801-2041 Tel: 781-904-2500 Fax: 781-904-2620 For information on all Butterworth-Heinemannpublications available, contact our World Wide Web home page at: http://www.bh.com 109 8 7 6 5 4 3 2 1 Printed in the United States of America
  3. 3. CONTENTSPreface, viiIn Memory, ixAbout the Author, xForeword, xiChapter 1. An Overview of Water and Wastewater Treatment, 1Introduction, 1What We Mean by Water F’urification, 4The Clean Water Act, 26Introducing the Physical Treatment Methods, 33Introducing Chemical Treatment, 37Energy Intensive Treatment Technologies, 40Water Treatment in General, 42Some General Comments, 56List of Abbreviations Used in this Chapter, 57Recommended Resources for the Reader, 58Questions for Thinking and Discussing, 60Chapter 2. What Filtration Is All About, 62Introduction, 62Terminology and Governing Equations, 63Filtration Dynamics, 72Wastewater Treatment Applications, 78Key Words, 81Nomenclature, 86Recommended Resources for the Reader, 87Questions for Thinking and Discussing, 89Chapter 3. Chemical Additives that Enhance Filtration, 91Introduction, 91Aluminum Based Chemical Additive Compounds, 91Iron-Based Compounds, 97Lime, 101SodaAsh, 104Liquid Caustic Soda, 105Filter Aids, 106 iii
  4. 4. Recommended Resources for the Reader, 120Questions for Thinking and Discussing, 122Chapter 4. Selecting the Right Filter M d a 123 ei,Introduction, 123Types of Filter Media to Choose From, 123Rigid Filter Media, 132General Properties of Loose and Granular Media, 142Filter Media Selection Criteria, 148Recommended Resources for the Reader, 152Questions for Thinking and Discussing, 155Chapter 5. What Pressure- and Cake-Filtration Are All About, 157Introduction, 157Constant Pressure Differential Filtration, 158Constant-Rate Filtration, 168Variable-Rate and -Pressure Filtration, 170Constant-Pressure and -Rate Filtration, 172Filter-Medium Filtration Formulas, 173Cake Filtration Equipment, 184Nomenclature, 213Recommended Resources for the Reader, 214Questions for Thinking and Discussing, 217Chapter 6. Cartridge and Other Filters Worth Mentioning, 224Introduction, 224Cartridge Filters, 224The Tilting Pan Filter, 228The Table Filter, 23 1Questions for Thinking and Discussing, 233Chapter 7. What Sand Filtration is All About, 235Introduction, 235Water Treatment Plant Operations, 236Granular Media Filtration, 243Let’s Take a Closer Look at Sand Filters, 247Slow Sand Filtration, 256Rapid Sand Filtration, 257Chemical Mixing and Solids Contact Processes, 260Recommended Resources for the Reader, 265 iv
  5. 5. Questions for Thinking and Discussing, 266Chapter 8. Sedimentation, Clarification, Flotation, and Coalescence, 268Introduction, 268Let’s Look at How a Single Particle Behaves in a Suspension, 269Gravity Sedimentation, 275The SedimentationProcess in Greater Detail, 282A Closer Look at Mechanical Clarification Process and the Chemistry ofClarification, 305Rectangular Sedimentation Tanks, 315Air Flotation Systems, 317Separation Using Coalescers, 323Nomenclature, 326Recommended Resources for the Reader, 328Questions for Thinking and Discussing, 331Chapter 9. Membrane Separation Technologies, 335Introduction, 335An Overview of Membrane Processes, 336What Electrodialysis Is, 339What Ultrafiltration Is, 344What Microfiltration and Nanofiltration Are, 354What Reverse Osmosis Is, 360Recommended Resources for the Reader, 367Questions for Thinking and Discussing, 370Chapter 10. Ion Exchange and Carbon Adsorption, 372Introduction, 372Theory and Practice of Ion Exchange, 374Carbon Adsorption in Water Treatment, 404Some Final Comments on Both Technologies, 432Recommended Resources for the Reader, 440Questions for Thinking and Discussing, 444Chapter 11. Water Sterilization Technologies, 446Introduction, 446What Waterborne Diseases Are, 446Treatment Options Available to Us, 450Ozonation, 454Ultraviolet Radiation, 455 V
  6. 6. Electron Beam, 455Biology of Aquatic Systems, 456Disinfection by Chlorination, 463Disinfection with Interhalogens and Halogen Mixtures, 476Sterilization Using Ozone, 482Chapter 1 . Treating the Sludge, 496 2Introduction, 496What Sludge Is, 497What Stabilization and Conditioning Mean, 501Sludge Dewatering Operations, 520Volume Reduction, 550What Finally Happens to Sludge after Volume Reduction, 565Final Comments and Evaluating Economics, 582Recommended Resources for the Reader, 592Questions for Thinking and Discussing, 594Glossary, 601Index, 631 vi
  7. 7. PrefaceThis volume covers the technologies that are applied to the treatment andpurification of water. Those who are generally familiar with this field willimmediately embrace the subject as a treatise on solid-liquid separations. However,the subject is much broader, in that the technologies discussed are not just restrictedto pollution control hardware that rely only upon physical methods of treating andpurifymg wastewaters. The book attempts to provide as wide a coverage as possiblethose technologies applicable to both water (e.g., drinking water) and wastewater(Le., industrial and municipal) sources. The methods and technologies discussedare a combination of physical, chemical and thermal techniques.There are twelve chapters. The first of these provides an orientation of terms andconcepts, along with reasons why water treatment practices are needed. Thischapter also sets the stage for the balance of the book by providing anorganizationalstructure to the subjects discussed. The second chapter covers the A-B-Cs of filtration theory and practices, which is one of the fundamental unitoperations addressed in several chapters of the book. Chapter 3 begins to discussthe chemistry of wastewater and focuses in on the use of chemical additives thatassist in physical separation processes for suspended solids. Chapters 4 through 7cover technology-specific filtration practices. There is a wide range of hardwareoptions covered in these three chapters, with applications to both municipal andindustrial sides of the equation. Chapter 8 covers the subjects of sedimentation,clarification flotation, and coalescence, and gets us back into some of the chemistryissues that are important achieving high quality water. Chapter 9 covers membraneseparation technologies which are applied to the purification of drinking water.Chapter 10 covers two very important water purification technologies that havefound applications not only in drinking water supply and beverage industryapplications, but in groundwater remediation applications. These technologies areion exchange and carbon adsorption. Chapter 11covers chemical and non-chemicalwater sterilizationtechnologies, which are critical to providing high quality drinkingwater. The last chapter focuses on the solid waste of wastewater treatment - sludge.This chapter looks not only at physico-chemical and thermal methods of sludgedewatering, but we explore what can be done with these wastes and their impact onthe overall costs that are associated with a water treatment plant operation. Sludge,like water, can be conditioned and sterilized, thereby transforming it from a costlywaste, requiring disposal, to a useful byproduct that can enter into secondarymarkets. Particular emphasis is given to pollution prevention technologies that arenot only more environmentally friendly than conventional waste disposal practices,but more cost effective.What I have attempted to bring to this volume is some of my own philosophy indealing with water treatment projects. As such, each chapter tries to embrace theindividual subject area from a first-principles standpoint, and then explore case-
  8. 8. specific approaches. Tackling problems in this field from a generalized approachoftentimes enables us to borrow solutions and approaches to water treatment froma larger arsenal of information. And a part of this arsenal is the worldwide Web.This is not only a platform for advertising and selling equipment, but there is awealth of information available to help address various technical aspects of watertreatment. You will find key Web sites cited throughout the book, which are usefulto equipment selection and sizing, as well as for troubleshooting treatment plantoperational problems.Most chapters include a section of recommended resources that I have relied uponin my own consulting practice over the years, and believe you will also. Inaddition, you will find a section titled Questions for Thinking and Discussing ineleven of the twelve chapters. These chapter sections will get you thinking aboutthe individual subject areas discussed, and challengeyou into applying some of thecalculation methods and methodologies reviewed. Although my intent was not tocreate a college textbook, there is value in using this volume with engineeringstudents, either as a supplemental text or a primary text on water treatmenttechnologies. If used as such, instructors will need to gauge the level ofunderstanding of students before specifying the book for a course, as well asintegrate the sequence and degree of coverage provided in this volume, foradmittedly, for such a broad and complex subject, it is impossible to provideuniform coverage of all areas in a single volume. My own experience in teachingshows that the subject matter, at the level of presentation in this volume is best suited to students with at least 3 years of engineering education under their belts.Another feature that is incorporated into each chapter is the use of sidebar discussions. These highlight boxes contain information and facts about each subject area that help to emphasize important points to remember, plus can assist plantmanagers in training technical staff, especially operators on the specifictechnologies relied upon in their operations. Finally, there is a Glossary of severalhundred terms at the end of the book. This will prove useful to you not only when reading through the chapters, but as a general resource reference. In some cases equipment suppliers and tradenames are noted, however these citations should not be considered an endorsementof products or services. They are cited strictly for illustrative purposes. Also recognize, that neither I, nor the publisher guarantee any designs emanating from the use of resources or discussions presented herein. Final designs must be based upon strict adherence to local engineering codes, and federal safety and environmental compliance standards. A heartfelt thanks is extended to Butterworth-Heinemann Publishers for their fine production of this volume, and in sharing my vision for this series, and to various companies cited throughout the book that contributed materials and their time Nicholas P. Cheremisinoff, Ph.D. Washington, D. C. viii
  9. 9. In MemoryThis volume is dedicated to the memory of Paul Nicholas Cheremisinofl, P.E.,who fathered a generation of pollution control and prevention specialists a New tJersey Institute of Technology. ix
  10. 10. About the AuthorNicholas P. Cheremisinoff is a private consultant to industry, lending institutions,and donor agencies, specializing in pollution prevention and environmentalmanagement. He has more than twenty years experience in applied research,manufacturingand internationalbusiness development, and has worked extensivelythroughout Russia, Eastern Europe, Korea, Latin America, and the United States.Dr. Cheremisinoff has contributed extensively to the industrial press, havingauthored, co-authored or edited more than 100 technical reference books, andseveral hundred articles, including Butterworth-Heinemann’sGreen Profits: TlteManager’s Handbook for I S 0 14001 and Pollution Ppeventiors. He received hisB. S ., M. S . and Ph.D. degrees in chemical engineering from Clarkson College ofTechnology. He can be reached by email at ncheremisi@aol.com. X
  11. 11. ForewordThis volume constitutes the beginning of what Butterworth-Heinemann Publishersand I hope to provide to environmental and pollution control engineerdmanagers,namely an authoritative and extensive reference series covering control equipmentand technologies. As a chemical engineer and a consultant, I not only had the greatfortune of having a father, who w s famous in the field of pollution control, but the aopportunity to work in consulting practice with him on a broad spectrum ofenvironmental problems within industry. We oftentimes talked and planned onwriting an authoritativevolume on the hardware and technologies available to solvepollution problems in the belief that, although there are many great works in thetechnical literature, the levels of presentations of this important subject varydramatically and the information is fragmented. With my father’s untimely deathin 1994, and my commitment to a multi-year assignment, dealing withenvironmental responsible care and the development of national environmentalpolicies in Ukraine and Russia, as part of contracts commitments to the U.S.Agency for International Development and the European Union, the originalvolume we intended was never written. Only now, having the opportunityto try andbring this work forward, I recognize that no single volume can do adequatejusticeto the subject area.Also, there is the misconception among a younger generation of engineers thatpollution control can be displaced by pollution prevention practices, and hencerecent times have de-emphasized the need for engineering innovative pollutioncontrols. I am a strong proponent of pollution prevention, and indeed havedeveloped an international consulting practice around it. However, we shouldrecognize that oftentimes pollution prevention relies upon essentially the identicaltechnologies that are applied to so-called “end-of-pipe” treatment. It is the mannerin whch these technologies are applied, along with best management practices,which enable pollution prevention to be practiced. As such, pollution preventiondoes not replace the need for pollution controls, nor does it replace entire processesaimed at cleaning or preventing pollutants from entering the environment. What itdoes do is channel our efforts into applying traditional end-of-pipe treatmenttechnologies in such manners that costly practices for the disposal of pollutants areavoided, and savings from energy efficiency and materials be achieved.The volume represents the initial fulfillment of a series, and is aimed at assistingprocess engineers, plant managers, environmentalconsultants, water treatmentplantoperators, and students. Subsequent volumes are intended to cover air pollutioncontrols, and solid waste management and minimization.This volume is a departure from the style of technical writing that I and many ofmy colleagues have done in the past. What I have attempted is to discuss thesubject, rather than to try and teach or summarize the technologies, the hardware,and selection criteria for different equipment. It’s a subject to discuss and explore,rather than to present in a dry, strictly technical fashion. Water treatment is not
  12. 12. only a very important subject, but it is extremely interesting. Its importance issimply one of environmental protection and public safety, because after all, wateris one of the basic natural elements we rely upon for survival. Even if we aredealing with non-potable water supplies, the impact of poor quality water to processoperations can be devastating in terms of achieving acceptableprocess efficienciesin heat exchange applications, in minimizing the maintenance requirements for heatexchange and other equipment, in the quality of certain products that rely on wateras a part of their composition and processing, and ultimately upon the economicsof a process operation. It’s a fascinating subject, because the technology is bothrapidly changing, and cost-effective, energy-saving solutions to water treatmentrequire innovative solutions. xii
  13. 13. Chapter 1 AN OVERVIEW OF WATER AND WASTE= WATER TREATMENTINTRODUCTIONWe may organize water treatment technologies into three general areas: PhysicalMethods, Chemical Methods, and Energy Intensive Methods. Physical methods ofwastewater treatment represent a body of technologies that we refer largely to assolid-liquid separations techniques, of which filtration plays a dominant role.Filtration technology can be broken into two general categories - conventional andnon-conventional. This technology is an integral component of drinking water andwastewater treatment applications. It is, however, but one unit process within amodern water treatment plant scheme, whereby there are a multitude of equipmentand technology options to select from depending upon the ultimate goals oftreatment. To understand the role of filtration, it is important to make distinctionsnot only with the other technologies employed in the cleaning and purification ofindustrial and municipal waters, but also with the objectives of different unitprocesses.Chemical methods of treatment rely upon the chemical interactions of thecontaminants we wish to remove from water, and the applicationof chemicals thateither aid in the separation of contaminants from water, or assist in the destructionor neutralization of harmful effects associated with contaminants. Chemicaltreatment methods are applied both as stand-alone technologies, and as an integralpart of the treatment process with physical methods.Among the energy intensive technologies, thermal methods have a dual role inwater treatment applications. They can be applied as a means of sterilization, thusproviding high quality drinking water, and/or these technologies can be applied tothe processing of the solid wastes or sludge, generated from water treatmentapplications. In the latter cases, thermal methods can be applied in essentially thesame manner as they are applied to conditioning water, namely to sterilize sludgecontaminated with organic contaminants, and/or these technologies can be appliedto volume reduction. Volume reduction is a key step in water treatment operations, 1
  14. 14. 2 WATER AND WASTEWATER TREATMENT TECHNOLOGIESbecause ultimately there is a tradeoff between polluted water and hazardous solidwaste.Energy intensive technologies include electrochemical techniques, which by andlarge are applied to drlnking water applications. They represent both sterilizationand conditioning of water to achieve a palatable quality.All three of these technology groups can be combined in water treatment, or theymay be used in select combinations depending upon the objectives of watertreatment. Among each of the general technology classes, there is a range of bothhardware and individual technologies that one may select from. The selection of notonly the proper unit process and hardware from within each technology group, butthe optimum combinations of hardware and unit processes from the four groupsdepends upon such factors as: 1. How clean the final water effluent from our plant must be;2. The quantities and nature of the influent water we need to treat;3. The physical and chemical properties of the pollutants we need to remove or render neutral in the effluent water;4. The physical, chemical and thermodynamic properties of the solid wastes generated from treating water; and5. The cost of treating water, including the cost of treating, processing and finding a home for the solid wastes.To understand this better, let us step back and start from a very fundamentalviewpoint. All processes are comprised of a number of unit processes, which arein t r made up of unit operations. Unit processes are distinct stages of a unmanufacturing operation. They each focus on one stage in a series of stages,successfully bringing a product to its final form. In this regard, a wastewatertreatment plant, whether industrial, a municipal wastewater treatment facility, ora drinlung water purification plant, is no different than, say, a synthetic rubbermanufacturing plant or an oil refinery. In the case of a rubber producing plant,various unit processes are applied to making intermediate forms of the product,which ultimately is in a final form of a rubber bale, that is sold to the consumer.The individual unit processes in this case are comprised of: (1) a catalyst reparation stage - a pre-preparation stage for monomers and catalyst additives; (2)polymerization - where an intermediate stage of the product is synthesized in the form of a latex or polymer suspended as a dilute solution in a hydrocarbon diluent; (3) followed by finishing - where the rubber is dried, residual diluent is removed and recovered, and the rubber is dried and compressed into a bale and packaged for sale. Each of these unit process operations are in t r comprised of individual unit un operations, whereby a particular technology or group pf technologies are applied, which, in turn,define a piece of equipment that is used along the production line. Drinking water and wastewater treatment plants are essentially no different. There are individual unit processes that comprise each of these types of plants that are applied in a succession of operations, with each stage aimed at improving the quality of the water as established by a set of product-performance criteria. The criteria focuses on the quality of the final water, which in the case of drinking water
  15. 15. AN OVERVIEW OF WATER AND WASTEWATER TREATMENT 3is establishedbased upon legal criteria (e.g., the Safe Drinking Water Act, SDWA),and if non-potable or process plant water, may be operational criteria (e.g., non-brackish waters to prevent scaling of heat exchange equipment).The number and complexity of unit processes and in turn unit operationscomprising a water purification or wastewater treatment facility are functions of thelegal and operational requirements of the treated water, the nature and degree ofcontaminationof the incoming water (raw water to the plant), and the quantities ofwater to be processed. This means then, that water treatment facilities from adesign and operational standpoints vary, but they do rely on overlapping and evenidentical unit processes.If we start with the first technology group, then filtration should be thought of asboth a unit process and a unit operation within a water treatment facility. As aseparate unit process, its objective is quite clear: namely, to remove suspendedsolids. When we combine this technology with chemical methods and applysedimentation and clarification (other physical separation methods), we can extendthe technology to removing dissolved particulate matter as well. The particulatematter may be biological, microbial or chemical in nature, As such, the operationstands alone within its own block within the overall manufacturing train of theplant. Examples of this would be the roughening and polishing stages of watertreatment. In turn, we may select or specify specific pieces of filtration equipmentfor these unit processes.The above gives us somewhat of an idea of the potential complexity of choosing theoptimum group of technologies and hardware needed in treating water. To developa cost-effective design, we need to understand not only what each of the unitprocesses are, but obtain a working knowledge of the operating basis and rangesfor the individual hardware. That, indeed, is the objective of this book; namely, totake a close look at the equipment options availableto us in each technology group,but not individually. Rather, to achieve an integrated and well thought out design,we need to understand how unit processes and unit operations compliment eachother in the overall design.This first chapter is for orientation purposes. Its objectives are to provide anoverview of water treatment and purification roles and technologies, and tointroduce terminology that will assist you in understanding the relation of thevarious technologies to the overall schemes employed in waster treatmentapplications. Recommended resources that you can refer to for more in-depthinformation are included at the end of each chapter. The organization of theseresources are generally provided by subject matter. Also, you will find a section forthe student at the end of each chapter that provides a list of Questionsfor ntinkingand Discussing. These will assist in reinforcing some of the principles and conceptspresented in each chapter, if the book is used as a primary or supplement textbook.We should recognize that the technology options for water treatment are great, andquite often the challenge lies with the selection of the most cost-effectivecombinations of unit processes and operations. In this regard, cost-factors areexamined where appropriate in our discussions within later chapters.
  16. 16. 4 WATER AND WASTEWATER TREATMENT TECHNOLOGIESWHAT WE MEAN BY WATER PURIFICATIONWhen we refer to water purification, it makes little sense to discuss the subjectwithout first identifying the contaminants that we wish to remove from water. Also,the source of the water is of importance. Our discussion at this point focuses ondrinking water. Groundwater sources are of a particular concern, because there aremany communities throughout the U.S. that rely on this form. The following aresome of the major contaminants that are of concern in water purificationapplications, as applied to drinking water sources, derived from groundwater. Surface Water Groundwater Public Water Surface Water Noncommunity ~ GroundwaterHeavy Metals - Heavy metals represent problems in terms of groundwaterpollution. The best way to identify their presence is by a lab test of the water or bycontacting county health departments. There are concerns of chronic exposure tolow levels of heavy metals in drinking water.Turbidity - Turbidity refers to suspended solids, i.e. muddy water, is very turbid.Turbidity is undesirable for three reasons:0 aesthetic considerations,0 solids may contain heavy metals, pathogens or other contaminants,
  17. 17. AN OVERVIEW OF WATER AND WASTEWATER TREATMENT 50 turbidity decreases the effectiveness of water treatment techniques by shielding pathogens from chemical or thermal damage, or in the case of UV (ultra violet) treatment, absorbing the UV light itself.Organic Compounds - Water can be contaminated by a number of organiccompounds, such as chloroform, gasoline, pesticides, and herbicides from a varietyof industrial and agricultural operations or applications. These contaminants mustbe identified in a lab test. It is unlikely groundwater will suddenly becomecontaminated, unless a quantity of chemicals is allowed to enter a well orpenetrating the aquifer. One exception is when the aquifer is located in limestone.Not only will water flow faster through limestone, but the rock is prone to formingvertical channels or sinkholes that will rapidly allow contamination from surfacewater. Surface water may show great variations in chemical contamination levelsdue to differences in rainfall, seasonal crop cultivation, m industrial effluent dlevels. Also, some hydrocarbons (the chlorinated hydrocarbons in particular) forma type of contaminant that is especially troublesome. These are a group ofchemicals known as dense nonaqueous phase liquids, or DNAPLs. These includechemicals used in dry cleaning, wood preservation, asphalt operations, machining,and in the production and repair of automobiles, aviation equipment, munitions, andelectrical equipment. These substances are heavier than water and they sink quicklyinto the ground. This makes spills of DNAPLs more difficult to handle than spillsof petroleum products. As with petroleum products, the problems are caused bygroundwater dissolving some of the compounds in these volatile substances. Thesecompounds can then move with the groundwater flow. Except in large cities,drinking water is rarely tested for these contaminants. Disposal of chemicals thathave low water solubility and a density greater than water result in the formationof distinct areas of pure residual contamination in soils and groundwater. Thesechemicals are typically solvents and are collectively referred to as Dense Non-Aqueous Phase Liquids (DNAPLs). Because of their relatively high density, theytend to move downward through soils and groundwater, leaving small amountsalong the migratory pathway, until they reach an impermeable layer where theycollect in discrete pools. Once the DNAPLs have reached an aquitard they tend tomove laterally under the influence of gravity and to slowly dissolve into thegroundwater, providing a long-term source for low level contamination ofgroundwater. Because of their movement patterns DNAPL contamination isdifficult to detect, characterize and remediate.Pathogens - These include protozoa, bacteria, and viruses. Protozoa cysts are thelargest pathogens in drinking water, and are responsible for many of the waterbornedisease cases in the U.S. Protozoa cysts range is size from 2 to 15 ,am (a micronis one millionth of a meter), but can squeeze through smaller openings. In order toinsure cyst filtration, filters with a absolute pore size of lpm or less should be used.The two most common protozoa pathogens are Giardia Zamblia (Giardia) andCryptosporidium (Crypto). Both organisms have caused numerous deaths in recentyears in the U.S. and Canada, the deaths occurring in the young and elderly, andthe sick and immune compromised. Many deaths were a result of more than one of
  18. 18. 6 WATER AND WASTEWATER TREATMENT TECHNOLOGIESthese conditions. Neither disease is likely to be fatal to a healthy adult, even ifuntreated. For example in Milwaukee in April of 1993, of 400,000 who werediagnosed with Crypto, only 54 deaths were linked to the outbreak, 84% of whomwere AIDS patients. Outside of the US.and other developed countries, protozoaare responsible for many cases of amoebic dysentery, but so far this has not beena problem in the U.S., due to the application of more advanced wastewatertreatment technologies. This could change during a survival situation. Tests havefound Giardia and/or Crypto in up to 5 % of vertical wells and 26% of springs inthe U.S.Bacteria are smaller than protozoa and are responsible for many diseases, such astyphoid fever, cholera, diarrhea, and dysentery. Pathogenic bacteria range in sizefrom 0.2 to 0.6 pm, and a 0.2 pm filter is necessary to prevent transmission.Contamination of water supplies by bacteria is blamed for the cholera epidemics,which devastate undeveloped countries from time to time. Even in the U.S., E. coli is frequently found to contaminated water supplies. Fomately, E. coli is relativelyharmless as pathogens go, and the problem isnt so much with E. coli found, but the fear that other bacteria may have contaminated the water as well. Never the less, dehydration from diarrhea caused by E. coli has resulted in fatalities. One of hundreds of strains of the bacterium Escherichia coli, E. coli 0157:H7 is an emerging cause of food borne and waterborne illness. Although most strains ofE. coli are harmless and live in the intestines of healthy humans and animals, this strain produces a powerful toxin and can cause severe illness. E. coli 0157:H7 was first recognized as a cause of illness during an outbreak in 1982 traced to contaminated hamburgers. Since then, most infections are believed to have come from eating undercooked ground beef. However, some have been waterborne. The presence of E. coli in water is a strong indication of recent sewage or animal waste contamination. Sewage may contain many types of disease-causing organisms. Since E. coli comes from human and animal wastes, it most often enters drinking water sources via rainfalls, snow melts, or other types of precipitation, E. coli may be washed into creeks, rivers, streams, lakes, or groundwater. When these waters are used as sources of drinking water and the water is not treated or inadequately treated, E. coli may end up in drinking water. E. coli 0157:H7 is one of hundreds of strains of the bacterium E. coli. Although most strains are harmless and live in the intestines of healthy humans and animals, this strain produces a powerful toxin and can cause severe illness. Infection often causes severe bloody diarrhea and abdominal cramps; sometimes the infection causes non-bloody diarrhea. Frequently, no fever is present. It should be noted that these symptoms are common to a variety of diseases, and may be caused by sources other than contaminated drinking water. In some people, particularly children under 5 years of age and the elderly, the infection can also cause a complication, called hemolytic uremic syndrome, in which the red blood cells are destroyed and the kidneys fail. About 2%-7% of infections lead to this complication. In the U.S. hemolytic uremic syndrome is the principal cause of acute kidney failure in children, and most cases of hemolytic uremic syndrome are caused by E. coli 0157:H7. Hemolytic uremic
  19. 19. AN OVERVIEW OF WATER AND WASTEWATER TREATMENT 7syndrome is a life-threatening condition usually treated in an intensive care unit.Blood transfusions and kidney dialysis are often required. With intensive care, thedeath rate for hemolytic uremic syndrome is 3 %-5%. Symptoms usually appearwithin 2 to 4 days, but can take up to 8 days. Most people recover withoutantibiotics or other specific treatment in 5-10 days. There is no evidence thatantibiotics improve the course of disease, and it is thought that treatment with someantibiotics may precipitate kidney complications. Antidiarrheal agents, such asloperamide (Imodium), should also be avoided. The most common methods oftreating water contaminated with E. coli is by using chlorine, ultra-violet light, orozone, all of which act to kill or inactivate E. coli. Systems, using surface watersources, are required to disinfect to ensure that all bacterial contamination isinactivated, such as E. coli. Systems using ground water sources are not requiredto disinfect, although many of them do. According to EPA regulations, a systemthat operates at least 60 days per year, and serves 25 people or more or has 15 ormore service connections, is regulated as a public water system under the SafeDrinking Water Act (SDWA). If a system is not a public water system as definedby EPAs regulations, it is not regulated under the SDWA, although it may beregulated by state or local authorities. Under the SDWA, EPA requires publicwater systems to monitor for coliform bacteria. Systems analyze first for totalcoliform, because this test is faster to produce results. Any time that a sample ispositive for total coliform, the same sample must be analyzed for either fecalcoliform or E. coli. Both are indicators of contamination with animal waste orhuman sewage. The largest public water systems (serving millions of people) musttake at least 480 samples per month. Smaller systems must take at least five samplesa month, unless the state has conducted a sanitary survey - a survey in which astate inspector examines system components and ensures they will protect publichealth - at the system within the last five years.Viruses are the 2nd most problematic pathogen, behind protozoa. As with protozoa,most waterborne viral diseases dont present a lethal hazard to a healthy adult.Waterborne pathogenic viruses range in size from 0.020-0.030 pm, and are toosmall to be filtered out by a mechanical filter. All waterborne enteric virusesaffecting humans occur solely in humans, thus animal waste doesnt present muchof a viral threat. At the present viruses dont present a major hazard to peopledrinking surface water in the U.S., but thls could change in a survival situation asthe level of human sanitation is reduced. Viruses do tend to show up even in remoteareas, so a case can be made for eliminating them now.THE DRINKING WATER STANDARDSWhen the objective of water treatment is to provide drinking water, then we needto select technologies that are not only the best available, but those that will meetlocal and national quality standards. The primary goals of a water treatment plant
  20. 20. 8 WATER AND WASTEWATER TREATMENT TECHNOLOGIES for over a century haveI What BATS Are remained practically the same: rp Inorganic Matter Ion Exchange Activated Alumina GAC namely to produce water that is biologically and chemically safe, is appealing to the consumer, and is noncorrosive and nonscaling. Today, plantI I design has become very Corrosion Control Corrosion complex from discovery of Inhibitors seemingly innumerable chemical substances, the multiplying of regulations, and trying to satisfy more discriminating palates. Inaddition to the basics, designers must now keep in mind all manner of legalmandates, as well as public concerns and en-vironmental considerations, to providean initial prospective of water works engineering planning, design, and operation.The growth of community water supply systems in the United States started in theearly 1800s. By 1860, over 400, and by the turn of the century over 3000 majorwater systems had been built to serve major cities and towns. Many older plantswere equipped with slow sand filters. In the mid 1890s, the Louisville WaterCompany introduced the technologies of coagulation with rapid sand filtration.The first application of chlorine in potable water was introduced in the 1830s fortaste and odor control, at that time diseases were thought to be spread by odors. Itwas not until the 1890s and the advent of the germ theory of disease that theimportance of disinfection in potable water was understood. Chlorination was firstintroduced on a practical scale in 1908 and then became a common practice.Federal authority to establish standards for drinking water systems originated withthe enactment by Congress in 1883 of the Interstate Quarantine Act, whichauthorized the Director of the United States Public Health Services (USPHS) toestablish and enforce regulations to prevent the introduction, transmission, orspread of communicable diseases.Today resource limitations have caused the United States Environmental ProtectionAgency (USEPA) to reassess schedules for new rules. A 1987 USEPA surveyindicated there were approximately 202,000 public water systems in the UnitedStates. About 29 percent of these were community water systems, which serveapproximately 90 percent of the population. Of the 58,908 community systems thatserve about 226 million people, 51,552 were classified as "small" or "very small. "Each of these systems at an average serves a population of fewer than 3300 people.The total population served by these systems is approximately 25 million people.These figures provide us with a magnitude of scale in meeting drinking waterdemands in the United States. Compliance with drinking water standards is not
  21. 21. AN OVERVIEW OF WATER AND WASTEWATER TREATMENT 9uniform. Small systems are the most frequent violators of federal regulations.Microbiological violations account for the vast majority of cases, with failure tomonitor and report. Among others, violations exceeding SDWA maximumcontaminant levels (MCLs) are quite common. Bringing small water systems intocompliance requires applicable technologies, operator ability, financial resources,and institutional arrangements. The 1986 SDWA amendments authorized USEPAto set the best available technology (BAT) that can be incorporated in the design forthe purposes of complying with the National Primary Drinking Water Regulations(NPDWR). Current BAT to maintain standards are as follows:For turbidity, color and microbiological control in surface water treatment:filtration. Common variations of filtration are conventional, direct, slow sand,diatomaceous earth, and membranes. What BATS Are Turbidity Color Filtration Microbial Micro- Disinfection organisms Chlorine Carbon Dioxide Chloramines Ozone I Organics Tower Aeration gr Diffused Aeration Oxidation Processes ROFor inactivation of microorganisms: disinfection. Typical disinfectants arechlorine, chlorine dioxide, chloramines, and ozone.For organic contaminant removal from surface water: packed-tower aeration,granular activated carbon (GAC), powdered activated carbon (PAC), diffusedaeration, advanced oxidation processes, and reverse osmosis (RO).For inorganic contaminants removal: membranes, ion exchange, activatedalumina, and GAC.
  22. 22. 10 WATER ANT) WASTEWATER TREATMENTTECHNOLOGIESFor corrosion control: typically, pH adjustment or corrosion inhibitors. Theimplications of the 1986 amendments to the SDWA and new regulations haveresulted in rapid development and introduction of new technologies and equipmentfor water treatment and monitoring over the last two decades. Biological processesin particular have proven effective in removing biodegradable organic carbon thatmay sustain the regrowth of potentially harmful microorganisms in the distributionsystem, effective taste and odor control, and reduction in chlorine demand and DBPformation potential. Both biologically-active sand or carbon filters provide costeffective treatment of micro-contaminants than do physicochernical processes inmany cases. Pertinent to the subject matter cover in this volume, membranetechnology has been applied in drinking water treatment, partly because ofaffordable membranes and demand to removal of many contaminants.Microflltration, ultrafiltration, nanofiltration and others have become commonnames in the water industry. Membrane technology is experimented with for theremoval of microbes, such as Giardia and Cryptosporidium and for selectiveremoval of nitrate. In other instances, membrane technology is applied for removalof DBP precursors, VOCs, and others.Other treatment technologies that have potential for full-scale adoption arephotochemical oxidation using ozone and UV radiation or hydrogen peroxide fordestruction of refractory organic compounds. One example of a technology thatwas developed outside North America and later emerged in the U.S. is the Habererprocess. This process combines contact flocculation, filtration, and powderedactivated carbon adsorption to meet a wide range of requirements for surface waterand groundwater purification.Utilities are seeking not only to improve treatment, but also to monitor theirsupplies for microbiologicalcontaminantsmore effectively. Electro-opticalsensorsare used to allow early detection of algal blooms in a reservoir and allow fordiagnosis of problems and guidance in operationalchanges. Geneprobe technologywas first developed in response to the need for improved identificationof microbesin the field of clinical microbiology. Attempts are now being made by radiolabeledand nonradioactivegene-probe assays with traditional detectionmethods for entericviruses and protozoan parasites, such as Giardia and Cryprosporidium. Thistechnique has the potential for monitoring water supplies for increasingly complexgroups of microbes.In spite of the multitudinous regulations and standards that an existing public watersystem must comply with, the principles of conventional water treatment processhave not changed significantly over half a century. Whether a filter contains sand,anthracite, or both, slow or rapid rate, constant or declining rate, filtration is stillfiltration, sedimentation is still sedimentation, and disinfection is still disinfection.What has changed, however, are many tools that we now have in our engineeringarsenal. For example, ,a supervisory control and data acquisition(SCADA) systemcan provide operators and managers with accurate process controI variables andoperation and maintenance records. In addition to being able to look at the various
  23. 23. AN OVERVIEW OF WATER AND WASTEWATER TREATMENT 11options on the computer screen, engineers can conduct pilot plant studies of themultiple variables inherent in water treatmentplant design. Likewise, operators andmanagers can utilize an ongoing pilot plant facility to optimize chemical feed anddevelop important information needed for future expansion and upgrading.Technology and ultimately equipment selection depends on the standards set by theregulations. Drinking water standards are regulations that EPA sets to control thelevel of contaminants in the nations drinking water. These standards are part of theSafe Drinking Water Acts "multiple barrier" approach to drinking waterprotection, which includes assessing and protecting drinking water sources;protecting wells and collection systems; making sure water is treated by qualifiedoperators; ensuring the integrity of distribution systems; and making informationavailable to the public on the quality of their drinking water. With the involvementof EPA, states, tribes, drinking water utilities, communities and citizens, thesemultiple barriers ensure that tap water in the U.S. and territories is safe to drink.In most cases, EPA delegates responsibility for implementing drinking waterstandards to states and tribes. There are two categories of drinking water standards:0 A National Primary Drinking Water Regulation (NPDWR or primary standard) is a legally-enforceable standard that applies to public water systems. Primary standards protect drinking water quality by limiting the levels of specific contaminants that can adversely affect public health and are known or anticipated to occur in water. They take the form of Maximum Contaminant Levels (MCL) or Treatment Techniques (TT).e A National Secondary Drinking Water Regulation (NSDWR or secondary standard) is a non-enforceable guideline regarding contaminants that may cause cosmetic effects (such as skin or tooth discoloration) or aesthetic effects (such as taste, odor, or color) in drinking water. EPA recommends secondary standards to water systems but does not require systems to comply. However, states may choose to adopt them as enforceable standards. This information focuses on national primary standards.Drlnking water standards apply to public water systems (PWSs), which providewater for human consumptionthrough at least 15 service connections, or regularlyserve at least 25 individuals. Public water systems include municipal watercompanies, homeowner associations, schools, businesses, campgrounds andshopping malls. EPA considers input from many individuals and groups throughoutthe rule-making process. One of the formal means by which EPA solicits theassistance of its stakeholders is the National Drinking Water Advisory Council(NDWAC). The 15-member committee was created by the Safe Drinking WaterAct. It is comprised of five members of the general public, five representatives ofstate and local agencies concerned with water hygiene and public water supply, andfive representations of private organizations and groups demonstrating an activeinterest in water hygiene and public water supply, including two members who areassociated with small rural public water systems.
  24. 24. 12 WATER AND WASTEWATER TREATMENT TECHNOLOGIESNDWAC advises EPAs Administrator on all of the agencys activities relating todrinlung water. In addition to the NDWAC, representatives from water utilities,environmental groups, public interest groups, states, tribes and the general publicare encouraged to take an active role in shaping the regulations, by participating inpublic meetings and commenting on proposed rules. Special meetings are also heldto obtain input from minority and low-income communities, as well asrepresentatives of small businesses.The 1996 Amendments to Safe Drinking Water Act require EPA to go throughseveral steps to determine, first, whether setting a standard is appropriate for aparticular contaminant, and if so, what the standard should be. Peer-reviewedscience and data support an intensivetechnologicalevaluation, which includesmanyfactors: occurrence in the environment;human exposure and risks of adverse healtheffects in the general population and sensitive subpopulations; analytical methodsof detection; technical feasibility; and impacts of regulation on water systems, theeconomy and public health. Considering public input throughout the process, EPAmust (1) identify drinking water problems; (2) establish priorities; and (3) setstandards.EPA must first make determinations about which contaminants to regulate. Thesedeterminations are based on health risks and the likelihood that the contaminantoccurs in public water systems at levels of concern. The National Drinking WaterContaminant Candidate List (CCL), published March 2, 1998, lists contaminantsthat (1) are not already regulated under SDWA; (2) may have adverse healtheffects; (3) are known or anticipatedto occur in public water systems; and (4) mayrequire regulations under SDWA. Contaminants on the CCL are divided intopriorities for regulation, health research and occurrence data collection.In August 2001, EPA selected five contaminants from the regulatory priorities onthe CCL and determined whether to regulate them. To support these decisions, theAgency determined that regulating the contaminants presents a meaningfulopportunity to reduce health risk. If the EPA determines regulations are necessary,the Agency must propose them by August 2003, and finalize them by February2005. In addition, the Agency will also select up to 30 unregulated contaminantsfrom the CCL for monitoring by public water systems serving at least 100,000people. Currently, most of the unregulated contaminantswith potential of occurringin drinkmg water are pesticides and microbes. Every five years, EPA will repeatthe cycle of revising the CCL, making regulatory determinations for fivecontaminants and identifyingup to 30 contaminantsfor unregulated monitoring. Inaddition, every six years, EPA will re-evaluate existing regulations to determine ifmodifications are necessary. Beginning in August 1999, a new NationalContaminant Occurrence Database was developed to store data on regulated andunregulated chemical, radiological, microbial and physical contaminants, and othersuch contaminantslikely to occur in finished, raw and source waters of public watersystems.
  25. 25. AN OVERVIEW OF WATER AND WASTEWATER TREATMENT 13After reviewing health effects studies, EPA sets a Maximum Contaminant LevelGoal (MCLG), the maximum level of a contaminant in drinking water at which noknown or anticipated adverse effect on the health of persons would occur, andwhich allows an adequate margin of safety. MCLGs are non-enforceable publichealth goals. Since MCLGs consider only public health and not the limits ofdetection and treatment technology, sometimes they are set at a level which watersystems cannot meet. When determining an MCLG, EPA considers the risk tosensitive subpopulations(infants, children, the elderly, and those with compromisedimmune systems) of experiencing a variety of adverse health effects. SOME IMPORTANT DEFINITIONS Maximum Contaminant Level (MCL) - The highest level of a contaminant that is allowed in drinking water. MCLs are set as close to MCLGs as feasible using the best available treatment technology and taking cost into consideration. MCLs are enforceable standards. Maximum Contaminant Level Goal (MCLG) - The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-enforceablepublic health goals. Maximum Residual Disinfectant Level (MRDL) - The highest level of a disinfectant allowed in drinking water. There is convincing evidence that addition of a disinfectant is necessary for control of microbial contaminants. Maximum Residual Disinfectant Level Goal (MRDLG) - The level of a drinking water disinfectant below which there is no known or expected risk to health. MRDLGs do not reflect the benefits o the use of disinfectants to control microbial f contaminants. Treatment Technique - A required process intended to reduce the level of a contaminant in drinking water.Non-Carcinogens (excluding microbial contaminants): For chemicals that cancause adverse non-cancer health effects, the MCLG is based on the reference dose.A reference dose (RFD) is an estimate of the amount of a chemical that a personcan be exposed to on a daily basis that is not anticipated to cause adverse healtheffects over a persons lifetime. In RFD calculations, sensitive subgroups areincluded, and uncertainty may span an order of magnitude. The RFD is multipliedby typical adult body weight (70 kg) and divided by daily water consumption (2liters) to provide a Drinking Water Equivalent Level (DWEL). Note that theDWEL is multiplied by a percentage of the total daily exposure contributed by
  26. 26. 14 WATER AMD WASTEWATER TREATMENT TECHNOLOGIESdrinking water to determine the MCLG. This empirical factor is usually 20 percent,but can be a higher value.Chemical Contaminants (Carcinogens):If there is evidence that a chemical maycause cancer, and there is no dose below which the chemical is considered safe, theMCLG is set at zero. If a chemical is carcinogenic and a safe dose can be determined, the MCLG is set at a level above zero that is safe.Microbid Contaminants: For microbial contaminants that may present publichealth risk, the MCLG is set at zero because ingesting one protozoa, virus, orbacterium may cause adversehealth effects. EPA is conducting studies to determinewhether there is a safe level above zero for some microbial contaminants. So far,however, this has not been established.Once the MCLG is determined, EPA sets an enforceable standard. In most cases,the standard is a Maximum Contaminant Level (MCL),the maximumpermissiblelevel of a contaminant in water which is delivered to any user of a public watersystem. The MCL is set as close to the MCLG as feasible, which the Safe DrinkingWater Act defines as the level that may be achieved with the use of the bestavailable technology, treatment techniques, and other means which EPA finds areavailable(after examination for efficiency under field conditions and not solelyunder laboratory conditions) are available, taking cost into consideration. Whenthere is no reliable method that is economically and technically feasible to measurea contaminant at particularly low concentrations, a Treatment Technique 0 isset rather than an MCL. A treatment technique (TT) is an enforceable procedureor level of technological performance which public water systems must follow toensure control of a contaminant. Examples of Treatment Technique rules are theSurface Water Treatment Rule (disinfection and filtration) and the Lead and CopperRule (optimized corrosion control). After determining a MCL or TT based onaffordable technology for large systems, EPA must complete an economic analysisto determine whether the benefits of that standardjust@ the costs. If not, EPA mayadjust the MCL for a particular class or group of systems to a level that "maximizeshealth risk reduction benefits at a cost that is justified by the benefits. IWHAT THE CURRENT DRINKING WATER STANDARDS AREThe following matrices provide you with a summary of the NPDWRs or primarystandards. You should visit the EPA Web site (www.epa.gov) and become familiarwith the various documents that are publically available. You will not only findthese regulations there, but detailed information that explains the reasoning behindeach MCLG. You will also find the entire legislation on this site and can becomefamiliar with all of the subtleties of this piece of complex environmental legislation.Tables 1 through 5 are derived from EPA Web site - www. gov/safauter. epa.
  27. 27. AN OVERVIEW OF WATER AND WASTEWATER TREATMENT 15Table 1. NPDW Regulations for Microorganisms.Microorganisms MCL or Potential Health Effects Sources of TT~ from Ingestion of Water Contaminant in Drinking Watercryptosporidim 0 as of Gastrointestinal illness Human and (e.g., diarrhea, vomiting, animal fecal waste 31,01,02: cramps) m3Giardia lamblia 0 IT3 Gastrointestinal illness Human and (e.g., diarrhea, vomiting, animal fecal waste cramps)Heterotrophic n/a TT3 HPC has no health effects, KPC measures aAate count but can indicate how range of bacteria effective treatment is at that are naturally controlling present in the microorganisms. environmentLegionella 0 TT3 Legionnaires Disease, Found naturally in commonly known as water; multiplies pneumonia in heating systemsTotal Coliforms 0 5.0%4 Used as an indicator that Coliforms are[including fecal other potentially harmful naturally present2oliform and E. bacteria may be present in theColi) environment; fecal coliforms and E. coli come from human and animal fecal waste.hrbidity n/a TT3 Turbidity, a measure of Isoil runoff water cloudiness, is used to indicate water quality and filtration effectiveness (e.g., whether disease- causing organisms are present). Higher turbidity is associated with higher levels of microorganisms such as viruses, parasites and some bacteria. These organisms can cause symptoms such as nausea, cramps, diarrhea, and associated headaches.Viruses (enteric) 0 TT3 Gastrointestinal illness Human and (e.g., diarrhedvomiting) animal fecal waste
  28. 28. 16 WATER AND WASTEWATER TREATMENT TECHNOLOGIESTable 2. NPDW Regulations for Disinfectants and Disinfection Byproducts. Disinfectants MCL or Potential Health Sources of & Disinfection TT Effects from Contaminant in Byproducts (mg/L) Ingestion of Water Drinking Water ~Bromate as of as of Increased risk of Byproduct of drinking 0 1101/02: D1/01/02: Cancer water disinfection zero 0.010Chloramines (as as of as of Eyehose irritation; Water additive usedC1J 01/01/02: 01/01/02: stomach discomfort, to control microbes MRDLG MRDL = anemia =4 1 4.0 as of as of Eyehose irritation; Water additive used stomach discomfort to control microbes 01/01/02: 01/01/02: MRDLG MRDL = = AI 4.0Chlorine dioxide as of as of Anemia; Water additive used(as ClO,) infants & Young to control microbes 01/o 1/02: 01/01/02: children: nervous MRDLG MRDL=O system effects =0.8 .8Chlorite as of as of Anemia; Byproduct of drinking 01/01/02: 01/01/02: infants YOU% water disinfection 0.8 children: nervous m0 system effectsHaloacetic acids as of as of Increased risk of Byproduct of drinkin$(HAAS) cancer water disinfection 01/01/02: 01/01/02: nla6 0.060 none 0.10 Liver, kidney or Byproduct of drinkingTrihalomethanes ___------- ---------- central nervous water disinfection as of as of system problems; 01/01/02: 01/01/02: increased risk of cancer nIa6 0.080Table 3. NPDW Regulations for Inorganic Chemicals. Sources of Drinking WaterIAntimony I 0.006 0.006 Increase in blood cholesterol; decrease in blood glucose Discharge from petroleum refineries; fire retardants;
  29. 29. AN O V E R m W OF WATER AND WASTEWATER TREATMENT 17Inorganic MCLG MCLor Potential Health Effects Sources ofChemicals (mdL) from Ingestion of Water Contaminant in TT1 Drinking Water (mg/L)2 ceramics; electronics solder4rsenic none 0.05 Skin damage; circulatory Erosion of natural system problems; increased deposits; runoff from risk of cancer glass & electronics production wastes2sbestos 7 million 7 MFL Increased risk of developing Decay of asbestosiber > 10 Fibers per benign intestinal polyps cement in waternicrorneter liter mains; erosion of natural deposits3arium Increase in blood pressure Discharge of drilling wastes; discharge from metal refineries erosion of natural deposits3eryllium Intestinal lesions Discharge from meta refineries and coal- burning factories; discharge from electrical, aerospace, and defense industrieCladmium Kidney damage Corrosion of galvanized pipes; erosion of natural deposits; discharge from metal refineries runoff from waste batteries and paintsClhromium 0.1 0.1 Some people who use water Discharge from steel:total) containing chromium well and pulp mills: in excess of the MCL over erosion of natural many years could deposits experience allergic dermatitisZopper 1.3 TT8Action Short term exposure: Corrosion of Level = 1.3 Gastrointestinal distress. household plumbing Long term exposure: Liver systems; erosion o f or kidney damage. natural depositszyanide (as Nerve damage or thyroid Discharge fromfree problems steel/metal factories;:yanide) discharge from plasti and fertilizer factorif
  30. 30. 18 WATER AND WASTEWATER TREATMENT TECHNOLOGIES Inorganic MCL o r Potential Health Effects Sources of Chemicals from Ingestion of Water Contaminant in TT Drinking Water (mgwFluoride 4.0 4.0 Bone disease (pain and Water additive which tenderness of the bones); promotes strong Children may get mottled teeth; erosion of teeth. natural deposits; discharge from fertilizer and aluminum factoriesLead zero TT*; Infants and children: Delays Corrosion of Action in physical or mental develor hamhold plumbing Level = Adults: Kidney problems; systems; erosion of 0.015 high blood pressure natural depositsMercury 0.002 0.002 Kidney damage Erosion of natural(inorganic) deposits; discharge from refineries and factories; runoff from , landfills and croplandNitrate 10 10 "Blue baby syndrome" in Runoff from fertilize](measured infants under six months - use; leaching fromas life threatening without septic tanks, sewage;Nitrogen) immediate medical attention. erosion of natural hymptoms: Infant looks deposits blue and has shortness of breath.Nitrite 1 1 "Blue baby syndrome" in Runoff from fertilize1(measured infants under six months - use; leaching fromas life threatening without septic tanks, sewage;Nitrogen) immediate medical attention. erosion of natural Symptoms: Infant looks deposits blue and has shortness of breath.Selenium 0.05 0.05 Hair or fingernail loss; Discharge from numbness in fingers or toes; petroleum refineries; circulatory problems erosion of natural deposits; discharge from minesThallium 0.0005 0.002 Hair loss; changes in blood; Leaching from ore- kidney, intestine, or liver processing sites; problems discharge from electronics, glass, and pharmaceutical
  31. 31. AN OVERVIEW OF WATER AND WASTEWATER TREATMENT 19Table 4. NPDW Regulations for Organic Chemicals. Organic MCLG Potential Health Sources of Chemicals (mg/L ) Effects from Contaminant in Ingestion of Water Drinking WaterAcrylamide zero TT9 Nervous system or Added to water blood problems; during increased risk of sewagelwastewater cancer treatmentAlachlor zero 0.002 Eye, liver, kidney or Runoff from spleen problems; herbicide used on anemia; increased row crops risk of cancerAtrazine 0.003 0.003 Cardiovascular Runoff from system problems; herbicide used on reproductive row crops difficultiesBenzene zero 0.005 Anemia; decrease in Discharge from blood platelets; factories; leaching increased risk of from gas storage cancer tanks and landfillsBenzo(a)pyrene O.OOO2 Reproductive Leaching fromFAHs) difficulties; linings of water increased risk of storage tanks and cancer distribution linesCarbofuran 0.04 0.04 Problems with blood Leaching of soil or nervous system; fumigant used on reproductive rice and alfalfa difticulties.Carbon zero 0.005 Liver problems; Discharge fromtetrachloride increased risk of chemical plants and cancer other industrial activitiesChlordane zero 0.002 Liver or nervous Residue of banned system problems; tenniticide increased risk of cancerChlorobenzene 0.1 Liver or kidney Discharge from problems chemical and agricultural chemical factories2,4-D 0.07 0.07 Kidney, liver, or Runoff from adrenal gland herbicide used on problems row crops
  32. 32. 20 WATER AND WASTEWATER TREATMFNI TECHNOLOGIESp-Dichlorobenzene 0.075 0.075 Anemia; liver, Discharge from kidney or spleen industrial chemical damage; changes in factories blood 1,Z-Dichloroethane zero 0.005 Increased risk of Discharge from cancer industrial chemical factories1,l- 0.007 0.007 Liver problems Discharge fromDichloroethylene industrial chemical factories cis-l,2- 0.07 0.07 Liver problems Discharge from Dichloroethylene industrial chemical factoriesI trans-1,Z Dichloromethane I 0.1 zero :I.;: 1 0.1 Liver problems problems; increased risk of cancer Discharge from factories Discharge from pharmaceutical and chemical factories Dichloropropanerv2- Di(Zethylhexy1) I zero 0.4 Increased risk of cancer Discharge from industrial chemical kactories General toxic effects Leaching from PVC adipate or reproductive Iplumbing systems; difficulties discharge from Di(2-ethy lhexy l) 0.006 Liver problems; Discharge from phthalate increased risk of rubber and chemical cancer
  33. 33. Ah OVERVIEW OF WATER AND WASTEWATER TREATMENT 21 , Organic MCLG Potential Health Sources of Chemicals (mg/L ) z Effects from 1 Contaminantin Ingestion of Water Drinking WaterDinoseb 0.007 0.007 Reproductive Runoff from difficulties herbicide used on soybeans and vegetablesDioxin (2,3,7,8- zero Emissions fromTCDD) difficulties; waste incineration increased risk of and other cancer combustion; discharge from chemical factoriesDiquat 0.02 Cataracts Runoff from ~ ~~ ~~ herbicide useEndothall 0.1 0.1 Stomach and Runoff from intestinal problems herbicide useEndrin 0.002 0.002 Nervous system Residue of banned effects insecticideEpichlorohydrin zero Stomach problems; Discharge from reproductive industrial chemical difficulties; factories; added to increased risk of water during cancer treatment processEthylbenzene 0.7 0.7 Liver or kidney Discharge from problems petroleum refineriesEthelyne dibromide zero O.ooOo5 Stomach problems; Discharge from reproductive petroleum refineries difficulties; increased risk of cancerGlyphosate 0.7 0.7 Kidney problems; ~ Runoff from reproductive herbicide use difficultiesIHeptachlor I zero 0.0004 Liver damage; risk of cancer IResidue of banned termiticide/Heptachlor epoxide I zero 0.0002 Liver damage; risk of cancer Breakdown of hepatachlorHexachlorobenzene I zero 0.001 Liver or kidney problems; reproductive Discharge from metal refineries and agricultural difficulties; risk of chemical factories
  34. 34. 22 WATER AND WASTEWATER TREATMENT TECHNOLOGIES ~ ~~~ Organic MCL or Potential Health sources of Chemicals TP Effects from Contaminant in (mg/L) Ingestion of Water Drinking Water [exachlorocyclopen 0.05 0.05 Kidney or stomach Xscharge from idiene problems :hemica1 factories (indane 0.0002 0.0002 Liver or kidney Lunaff/leaching problems ?om insecticide ised on catttle, umber, gardens fethoxychlor 0.04 0.04 Reproductive Runoff/Ieaching difficulties ?om insecticide i s e d on fruits, yregetables, alfalfa, ivestock bxamyl (Vydate) 0.2 0.2 Slight nervous Run0f f h c h i n g system effects from insecticide llsed on apples, ?otatoes, and tomatoes 01ychlorinated zero 0.0005 Skin changes; Runoff from iphenyls (PCBs) thymus gland landfils; discharge problems; immune 3f waste chemicals deficiencies; reproductive or nervous system difficulties; increased risk of cancer entachlorophenol zero 0.001 Liver or kidney Discharge From problems; increased wood preserving risk of cancer factories icloram 0.5 0.5 Liver problems Herbicide runoff timazine 0.004 0.004 Problems with blood Herbicide runoff ltyrene 0.1 0.1 Liver, kidney, and Discharge from circulatory problems rubber and plastic factories; leaching from landfills :etrachloroethylene zero 0,005 Liver problems; Discharge from increased risk of factories and dry cancer cleaners :oluene 1 1 Nervous s s e , ytm Discharge from kidney, or liver petroleum factories problems
  35. 35. AN OVERVIEW OF WATER AND WASTEWATER TREATMENT 23 ~~ ~ Organic MCLG Potential Health Sources of Chemicals (mglL ) f Effects from Contaminant in Drinking Water Toxaphene zero Kidney, liver, or Runoff/leaching thyroid problems; from insecticide increased risk of used on cotton and cancer cattle 2,4,5-TP (Silvex) 0.05 0.05 Residue of banned herbicide/L.234- Trichlorobenzene I 0.07 0.07 0.2 Changes in adrenal glands ~~ Liver, nervous ~ Discharge from textile finishing factories Discharge from Trichloroethane system, or metal degreasing circulatory problems sites and other factories 0.003 0.005 Liver, kidney, or Discharge from Trichloroethane immune system industrial chemical problems factories 0.005 Liver problems; Discharge from increased risk of petroleum refineries cancer 0.002 Increased risk of Leaching from PVC cancer pipes; discharge from plastic factories Xylenes (total) I lo 10 Nervous system damage Discharges from petroleum and chemical plantsTable 5 . NPDW Regulations for Radionuclides.~ Radionuclides MCLG MCL or Potential Health Sources of Contaminant (mgW TT Effects from in Drinking Water (mg/L)2 hgestion of -I Water 15 Increased risk of Erosion of natural deposits picocuries cancer per Liter (pCi/L) 12/08/03: zero
  36. 36. 24 WATER AND WASTEWATER TREATMENT TECHNOLOGIES Radionuclides MCL or Potential Health Sources of Contaminant Effects from i Drinking Water n Ingestion ofBeta particles and 4 millirems Increased risk of Decay of natural and man-photon emitters per year cancer nade deposits 12/08/03: Erosion of natural depositsRadium 228(combined) I ItUranium 12/08/03: fosa zero as of I I as of /Increased risk of Erosion of natural depositsThe following footnotes apply to the above tables. cancer, kidney* Definitions: Refer to the discussion box on page 12. Units are in milligrams per liter (mg/L) unless otherwise noted. Milligrams perliter are equivalent to parts per million. EPAs surface water treatment rules require systems using surface water orground water under the direct influence of surface water to (1) disinfect their water,and (2) filter their water or meet criteria for avoidmg filtration so that the followingcontaminants are controlled at the following levels:0 Cryptosporidium: (as of January 1, 2002) 99 % removalhnactivation0 Giardia lamblia: 99.9% removal/inactivation Viruses: 99.99%rernovalhnactivation0 Legionella: No limit, but EPA believes that if Giardia and viruses are removedhactivated, Legionella will also be controlled.0 Turbidity: At no time can turbidity (cloudiness of water) go above 5 nephelolometric turbidity units (NTU); systems that filter must ensure that the turbidity go no higher than 1 NTU (0.5 NTU for conventional or direct filtration) in at least 95%of the daily samples in any month. As of January 1,2002, turbidity may never exceed 1 NTU, and must not exceed 0.3 NTU in 95 5% of daily samples in any month0 HPC: No more than 500 bacterial colonies per milliliter.
  37. 37. AN OVERVIEW OF WATER AND WASTEWATER TREATMENT 25 No more than 5.0% samples total coliform-positive in a month. (For watersystems that collect fewer than 40 routine samples per month, no more than onesample can be total coliform-positive). Every sample that has total coliforms mustbe analyzed for fecal coliforms. There may not be any fecal coliforms or E. coli. Fecal coliform and E. coli are bacteria whose presence indicates that the watermay be contaminated with human or animal wastes. Disease-causing microbes(pathogens) in these wastes can cause diarrhea, cramps, nausea, headaches, or othersymptoms. These pathogens may pose a special health risk for infants, youngchildren, and people with severely compromised immune systems. Although there is no collective MCLG for this contaminant group, there areindividual MCLGs for some of the individual contaminants: Trihalomethanes: bromodichloromethane (zero); bromoform (zero); dibromochloromethane (0.06 mg/L). Chloroform is regulated with this group but has no MCLG.e Haloacetic acids: dichloroacetic acid (zero); trichloroacetic acid (0.3 mg/L). Monochloroacetic acid, bromoacetic acid, and dibromoacetic acid are regulated with this group but have no MCLGs. MCLGs were not established before the 1986 Amendments to the Safe DrinkingWater Act. Therefore, there is no MCLG for this contaminant. Lead and copper are regulated by a Treatment Technique that requires systems tocontrol the corrosiveness of their water. If more than 10% of tap water samplesexceed the action level, water systems must take additional steps. For copper, theaction level is 1.3 mg/L, and for lead is 0.015 mg/L. Each water system must certify, in writing, to the state (using third-party ormanufacturers certification)that when acrylamide and epichlorohydrinare used indrinking water systems, the combination (or product) of dose and monomer leveldoes not exceed the levels specified, as follows:e Acrylamide = 0.05% dosed at 1 mg/L (or equivalent) Epichlorohydrin = 0.01% dosed at 20 mg/L (or equivalent)NATIONAL SECONDARY DRINKING WATER REGULATIONSNational Secondary Drinking Water Regulations (NSDWRs or secondary standards)are non-enforceable guidelines regulating contaminants that may cause cosmeticeffects (such as skin or tooth discoloration)or aesthetic effects (such as taste, odor,or color) in drinking water. EPA recommends secondary standards to watersystems but does not require systems to comply. However, states may choose toadopt them as enforceablestandards. The following table summarizesthe secondarystandards.