bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling Hydrodynamics and Ozone Residual Distribution in a Pilot‐Scale Ozone Bubble‐Diffuser Contactor
Authors: Mariñas Benito J. , Liang Sun , Aieta E. Marco
Published: February 2018

Mixing conditions inside a pilot‐scale ozone bubble‐diffuser contactor and the effect of mixing on ozone residual concentrations were investigated. The 17‐ft‐high, 6‐in.‐diameter contactor was operated with both counter‐current and cocurrent water and gas flows. When the contactor was operated in the cocurrent mode, it was packed with 1‐in. plastic saddles. Tracer and ozonation tests showed that mixing conditions in the contactor ranged from nearly plug‐flow to well mixed. Dispersion increased as the gas flow rate increased and as the water flow rate decreased, with the latter dependency being stronger. The lowest dispersions were observed for tests run with the cocurrent packed contactor. A computer model was developed and used to predict dispersion numbers, ozone concentration profiles, ozone residuals, and C × T parameters. Disagreements between observed and predicted tracer curves might have been caused by short‐circuiting, but in general the model predicted ozone residuals well.
Computer Applications in the Water Industry
Authors: Purves Amy J. , Cesario A. Lee
Published: February 2018

The use of automated mapping/facilities management, geographic information systems (GIS), and computer aided design‐drafting (CAD) technology within the water industry was surveyed by the AWWA Computer Assisted Design Committee. Of the 270 respondents, only 20 percent indicated that they had no involvement in computerization in these areas. In addition to standard applications such as engineering drafting and facilities mapping, utilities are using raster data for document imaging and integration of raster and vectorized data and developing interfaces between GIS and other systems such as supervisory control and data acquisition, customer billing, and hydraulic models. The most common approach to GIS data base development is photogrammetric compilation of a base map and digitizing locations of facilities, although there is strong interest and some activity in scanning and vectorizing existing maps of facilities.
Ion Exchange for Nitrate Removal
Authors: Cliford Dennis , Liu Xiaosha
Published: February 2018

A bench‐scale ion exchange process with batch biological denitrification of the spent regenerant brine was developed to remove nitrate from drinking water. This research indicates that the combination procedure results in 50 percent reduction of regenerant consumption and 90 percent reduction in the mass of waste salt discharged. The process features a sequencing batch reactor to accomplish the biological denitrification of a 0.5 N sodium chloride spent regenerant solution. Now being pilot tested in California, the process—which is simple, flexible, and reliable—should be suitable for use by small systems.
Involving the Public in Developing Regulations
Authors: Pontius Frederick W.
Published: February 2018

The US Environmental Protection Agency (USEPA) is charged by the US Congress with administering the Safe Drinking Water Act (SDWA) for the purpose of protecting public health and welfare. Under the authority of the SDWA the agency establishes regulations that apply to US public water systems. New regulations are set by USEPA in accordance with the requirements of the SDWA. Public involvement in the development of regulations is recognized by USEPA and others as an important aspect of the regulatory process. But getting involved in the regulatory process can be frustrating unless you know how to make your voice heard. How the public can participate in the process is the subject of this article.
Testing a Coke Biofilter for the Pretreatment of Polluted Surface Water in Taiwan
Authors: Yeh Hsuan‐Hsien , Kao Hsien‐Cheng
Published: February 2018

When polluted waters containing high concentrations of ammonia‐nitrogen and organics are treated with prechlorination, the excessive dosages of chlorine required produce chloroform and other trihalomethanes in the finished water. In an attempt to avoid the use of prechlorination, packed‐bed filtration alone and packed‐bed filtration preceded by ozonation were studied side by side. The results indicate that packed‐bed filters using coke and gravel as the media can remove >90 percent of the ammonia‐nitrogen when the volumetric loading is <300 g NH4+‐N/m3d. Organics are also removed, but to a lesser extent. Ozonation did not seem to significantly improve the performance of the biological filters. The dissolved oxygen content of the water was important in controlling the performance of the filters. In general, packed‐bed filtration Was found to be effective for reducing the dosage of chlorine needed for prechlorination.
Financing Assistance Available fox Small Public Water Systems
Authors: Campbell Susan , Jr. Benjamin W. Lykins , Goodrich James A.
Published: February 2018

Many small and very small drinking water systems require repair and upgrading if they are to comply with the Safe Drinking Water Act of 1974 and its amendments. Often, dispersed population makes infrastructure expensive on a per‐capita basis. Funding shortages at the federal, state, and water system levels compound the problem, leading to budget deficits, layoffs, and furloughs that affect small systems' capability to conduct repairs. Various alternative financial assistance mechanisms are available to small systems to fund improvements. The funding options include loans and grants from federal and state agencies, banks, foundations, and other sources. This article provides a comprehensive review of the sources of such financial assistance. In addition, it supplies names of publications that can direct the reader to further assistance.
Developing Models for Assessing the Financial Health of Small and Medium‐Sized Water Utilities
Authors: Dreese G. Richard , Beecher Janice A.
Published: February 2018

This article reviews failure‐prediction models that have appeared in the financial literature and describes development of a distress classification model for water utilities. The methodology can be used as an early‐warning system to identify failing water utilities, as a screening tool for systems seeking certification, and as a viability test for evaluating prospective structural changes to existing systems. Although financial models are useful as a general screening and evaluation device, the authors caution that they do not fully capture other factors important to viability, such as managerial and technical capability or a community's ability to support water system costs.
Influence of Bromide on Low‐Pressure Membrane Filtration for Controlling DBPs in Surface Waters
Authors: Laîné Jean‐Michel , Jacangelo Joseph G. , Cummings Edward W. , Carns Keith E. , Mallevialle Joël
Published: February 2018

As a result of current and anticipated disinfection by‐product (DBP) regulations, increased interest is being shown in pressure‐driven membrane processes for DBP precursor removal. Pilot studies were conducted with two California surface waters and one in Ottawa, Ont. One ultratiltration (UF) membrane with a molecular weight cutoff (MWCO) of 100,000 daltons and four nanofiltration (NF) membranes with MWCOs ranging from 200 to 800 daltons were evaluated. Results indicated that UF was ineffective for controlling the formation of DBPs. When little or no bromide was detected in the permeate, hollow‐fiber NF membranes with MWCOs of 400–800 daltons effectively controlled DBP formation. In waters containing bromide, higher bromoform concentrations (compared with the raw water) were observed after chlorination of the permeate of these membranes. Use of spiral‐wound NF membranes (200–300 daltons) controlled the formation of brominated THMs, but pretreatment of the water was necessary.
Computer‐Generated Pumping Schedules for Satisfying Operational Objectives
Authors: Chase Donald V. , Ormsbee Lindell E.
Published: February 2018

A new computer program can assist engineers, water utility managers, and pump station operators in selecting the most cost‐effective combination of pumps to meet a specific system requirement over a given time period. The program provides operators with two options: (1) finding the least‐cost pump combination that will place tank levels at desired elevations at the end of a specified time period, and (2) finding the most efficient pump combination that will supply a required pump demand over a specified time period. It is expected that such a tool will not only improve the overall operation of a system but will also allow insight into system performance.
Examining the Relationship Between Iron Corrosion and the Disinfection of Biofilm Bacteria
Authors: LeChevallier Mark W. , Lowry Cheryl D. , Lee Ramon G. , Gibbon Donald L.
Published: February 2018

Previous research has shown a relationship between corrosion of an iron pipe and the protection of biofilm bacteria from disinfection. It is believed that the corrosion product reacts with chlorine disinfectants and prevents the biocide from penetrating the biofilm layer and inactivating the attached bacteria. The results of the current study show that even low levels of corrosion, i.e., <1 mpy, could interfere with free chlorine disinfection. High corrosion rates affected monochloramine disinfection. The research also suggested that the type of corrosion influences the efficiency of disinfection of the biofilm. Increases in the ratio of chloride and sulfate to bicarbonate (the Larson index) have been shown to be associated with pitting corrosion, which appears to interfere with disinfection more than general corrosion. Multiple linear regression models were able to predict approximately 75 percent of the variation in biofilm inactivation. Provided that low corrosion rates and Larson indexes are achieved, no one corrosion inhibitor is preferred over another to control biofilm bacteria. The authors recommend that water utilities monitor and control corrosion rates and Larson indexes to levels as low as feasible.
Marginal‐Cost Pricing: Its Rle in Conservation
Authors: Mann Patrick C. , Clark Don M.
Published: February 2018

Marginal‐cost analysis is critical to a conservation program because all management decisions affecting conservation require a comparison of costs and benefits. Increasing production within existing facilities requires that the revenues derived from the additional sales be compared with the higher operations costs. Also, a decision to expand capacity requires a comparison between expected revenues and the capital and operations costs of the new facilities. An approach is presented for the design of water rates that combines economic theory with the practical aspects of integrated resource planning. Marginal‐cost savings are compared with changes in discretionary use, resulting in the calculation of a conservation surcharge. This surcharge is a strong conservation price signal that is relatively easy to administer and that results in economic efficiency.
Evaluating the Effect of Residential Water Audits
Authors: Bruvold William H. , Mitchell Patrick R.
Published: February 2018

The residential water audit program conducted by the Contra Costa Water District of Concord, Calif., in the summer of 1989 was evaluated to determine savings as average gallons per day per account (gpd/account) by three estimation procedures: (1) the constructed comparison group, (2) direct estimation, and (3) statistical modeling. The 1989 residential audit program was estimated to have yielded average savings of about 30 gpd/account (or 6 percent) from September 1989 through August 1990, resulting in aggregate savings of about 10 mil gal. These estimates are similar to those obtained from the residential audit program conducted in Concord in 1988 and from evaluation of similar audits conducted in Pasadena and Novato, Calif. A number of recommendations were made on the basis of the audit findings.
Using Coefficients to Predict Dynamic Flow Torque for Quarter‐Turn Valves
Authors: Rahmeyer William J.
Published: February 2018

Quarter‐turn types of valves are subject to stresses and torques produced by the flow forces in the valve and by the rotation of the valve disk with an actuator. This article discusses the different types of torque to which a valve can be exposed, focusing on the use of dynamic flow torque coefficients to predict and evaluate flow torque. The derivation of a torque coefficient that incorporates the variation of geometry for different sizes of a valve is presented. The coefficient also utilizes a correction factor for the loss coefficient and gas expansion. A method and a scaling factor to correct flow torque coefficients for different valve sizes and loss coefficients are described. Several examples and plots of torque coefficients are included for various valve types.
The Emperor Has No Clothes
Authors: Allen Martin J.
Published: February 2018

In this critique of the water quality regulations, the author maintains that a misguided Congress created a regulatory mess when it reauthorized the Safe Drinking Water Act in 1986. Regulations are now driven by deadline, not science, and the emphasis on compliance and enforcement actions is blind at best. Everyone in the water supply community wants to provide safe, reliable, and affordable drinking water, but the current regulatory mess hampers rather than enhances the effort. As Congress begins the long journey to the next SDWA reauthorization, the water supply community must educate congressmen. If members of Congress are armed with information about the projected costs and realistic benefits of the regulations, they may change some of the law's requirements when they reauthorize it.
USEPA Drinking Water Laboratory Certification Program
Authors: Feige Mary Ann , Madding Caroline , Glick Edward M.
Published: February 2018

The Drinking Water Laboratory Certification Program has been in existence since 1943 and was adopted by the Drinking Water Program in 1978 under the authority given the US Environmental Protection Agency (USEPA) by the Safe Drinking Water Act (SDWA). Both USEPA and the states are looking for ways to make the program efficient in the face of dwindling resources. Recent discussions concerning the certification program have included major new approaches. With impending reauthorization of the SDWA and the changing needs of the certification community, the program could be significantly modified.
D–DBP Rule to Set Tight Standards
Authors: Pontius Frederick W.
Published: February 2018

This article summarizes the results of the regulatory‐negotiation, or reg‐neg, process that was invoked to develop regulations for disinfectants and disinfection by‐products. The content of the September 1993 draft rule is discussed here. There could be additional changes as the final rule is developed. The negotiating process is almost complete and is expected to result in the development of three closely related rules: the Disinfectants‐Disinfection By‐Products Rule; the Enhanced Surface Water Treatment Rule (ESWTR); and the Information Collection Rule (ICR), which is designed to support the other two rule‐makings. An overview of the three rules has been presented and the ICR has also been described in detail. The ESWTR will be the subject of a future article.
Surviving the flood: teamwork pays off in Des Moines
Authors: McMullen L.D.
Published: February 2018

L.D. McMullen recounts the hour‐by‐hour drama of how the Des Moines Water Works battled the rising Raccoon River and restored water service to residents last summer.

Teamwork and communication saved the day last summer for the Des Moines Water Works. Massive flooding shut down the plant in mid‐July and left 250,000 people without drinking water. The utility had been thought to be safe; 25‐ft levees separated it from the Raccoon River, and the previous record flood level had been 19.5 ft in 1947. Last summer, though, the river crested at nearly 27 ft. Utility employees, their efforts to protect the plant unsuccessful, turned their attention to equipment repair and restoration of service. Utility General Manager L.D. McMullen describes how employees met the stated goal of “seven days to pump; thirty days to drink.” He credits the utility's team structure, regular communication among workers and between the utility and the public, and support from citizens, employees' families, local businesses, and suppliers.
Examining the reactions between soluble iron, DOC, and alternative oxidants during conventional treatment
Authors: Knocke William R. , Shorney Holly L. , Bellamy Julia D.
Published: February 2018

Speciation of iron is necessary in assessing whether oxidant addition will prove advantageous during treatment.

Greater knowledge of the interaction between soluble iron, dissolved organic carbon (DOC), and alternative oxidants is warranted if the latter are to be optimized for iron removal. An important conclusion of the work is that speciation of iron (differentiation of particulate, colloidal, and soluble forms) in source‐ and treated‐water samples is needed to determine whether oxidant addition will prove advantageous. Source waters that contain predominantly particulate or colloidal iron may be effectively treated by coagulation and separation processes alone, whereas removal of soluble iron requires the addition of any one of the oxidants studied: potassium permanganate, chlorine dioxide, or hypochlorous acid. Both the concentration and nature of DOC in water were found to affect the residual iron speciation that followed oxidant addition.
Are water rates becoming unaffordable?
Authors: Rubin Scott J.
Published: February 2018

The problem of affordability of drinking water is not limited to customers of small or rural water systems.

National trends in water rates and income levels are examined to determine whether water rates are becoming unaffordable. A more detailed analysis of water rates and income distributions is conducted for 168 water suppliers in Pennsylvania. The author concludes that rates are increasing much more rapidly than income levels for low‐income water customers. Further, the ability of customers to afford water service appears most at risk in large water systems, even though those systems tend to be publicly owned and have lower rates than investor‐owned systems. Overall, anywhere from one in four to one in six water customers is currently paying more than 2 percent of household income for water service. Expected rate increases will place increased pressure on water utilities and all levels of government to develop policies and rate structures to ensure the continued provision of water service to low‐income households.
A volumetric method for assessing Giardia inactivation
Authors: Haas Charles N. , Hornberger Joel C. , Anmangandla Uma , Heath Mark , Jacangelo Joseph G.
Published: February 2018

Based on these tests, the results of the proposed volumetric method—which has the advantage of reducing labor requirements—were indistinguishable from those of the standard method.

Because the standard method of determining Giardia inactivation in disinfection tests—which involves counting dead and living organisms—can be extremely tedious, an alternative method, whereby the concentration of only viable trophozoites is estimated, is being sought. This article describes the development of such a volumetric method and its verification by comparing the results obtained with the standard and volumetric methods. This work demonstrates that the two methods yield equivalent results—at least for the disinfectants and waters examined. Whether this equivalence operates for larger‐scale concentration techniques and for different waters, disinfectants, and organisms remains open to further research.
Privatizing infrastructure options for municipal systems
Authors: Haarmeyer David
Published: February 2018

Privatization, which operates successfully in France and Britain, offers municipalities a way to harness private‐sector resources and incentives to improve water supply systems.

Municipal water supply systems face little competition and generally cannot go bankrupt, so they lack incentives to operate efficiently. Private systems also face problems: rate regulation removes incentives to innovate, and because private systems pay taxes, they are at a competitive disadvantage. To “level the playing field” in the United States, publicly owned water‐supply companies could be transformed into stand‐alone, government‐owned enterprises subject to the same tax and regulatory policies as private water companies. Both this transitory phase and full privatization would expand a municipality's tax base, encourage full‐cost pricing, and lead to less reliance on government financing to upgrade facilities and meet drinking water regulations.
Privatizing the Mexican water industry
Authors: Casasús Carlos
Published: February 2018

Access to basic services plus betterment of water and sewer systems led to the privatization of Mexico's water industry.

Mexico has begun to privatize its water industry in an attempt to provide better water service and produce revenues that match costs. Privatization does not follow the traditional scheme, however. It is structured in the form of a management contract in which the ownership of the infrastructure and control over the politics of implementing the new billing systems remain in the hands of Mexico City's government.
Competitive Adsorption of VOCs and BOM: the Role of Molecular Oxygen
Authors: Sorial George A. , Cerminara Perry , Papadimas Spyridon P. , Suidan Makram T. , Speth Thomas F.
Published: February 2018

Molecular oxygen further reduced the adsorptive capacity of carbon for the volatile organics studied.

In this study, the presence of background organic matter (BOM) was seen to reduce the adsorptive capacity of carbon for chloroform, chlorobenzene, and dibromochloropropane. Adsorption of these compounds was further reduced under oxic conditions. This additional reduction in capacity was likely due to conglomeration of BOM on the carhon surface, which reduced the available surface area for the target volatile organic chemical (VOC). Adsorption isotherms conducted with constant initial concentration ratios of VOC to BOM showed similar behavior. The ideal adsorbed solution theory (IAST) was found to accurately describe anoxic adsorption isotherms for VOCs in water containing BOM but failed to predict this competition for data collected under oxic conditions.
A Look At The Federal Drinking Water Revolving Loan Fund Proposals
Authors: Pontius Frederick W.
Published: February 2018

The lack of funding is a primary reason behind the difficulty many water systems have with installing needed treatment, upgrading existing systems, or making other improvements necessary to meet new regulations set under the Safe Drinking Water Act (SDWA). Providing a mechanism for federal funding for drinking water systems is a key objective of pending legislation. Current legislative proposals are patterned after the state revolving loan fund (SRF) concept used for funding wastewater treatment facilities under the Clean Water Act (CWA). The federal government would provide capitalization grants to states that meet the minimum requirements set by the US Environmental Protection Agency (USEPA). The states would provide loans and other financial assistance to eligible water systems who would repay the loans, thereby perpetuating the fund.
Taking the initiative
Authors: Reid Joe
Published: February 2018

AWWA's new president is focused on getting the organizational framework established for three initiatives—safe drinking water for all, customer satisfaction, and total water management.

Robert L. Wubbena, incoming AWWA president, discussed the broadening scope of the water industry and AWWA's part in it during an April 29 conversation at AWWA headquarters with Joe Reid, managing editor of Waterweek. As president, Wubbena will automatically be a member of the Executive Committee and Board of Directors, and he will also be involved with numerous other committees. Previously he has served AWWA through the General Policy Council, Management Division (chair), Education Division, AWWA/WEF Joint Management Conference (co‐chair), and the Wetlands Technical Advisory Workgroup. He has also served as a Pacific Northwest Section officer and received its Fuller Award in 1982. Wubbena, president of Economic & Engineering Services Inc. in Olympia, Wash., is active in the community and belongs to several other professional organizations. He holds bachelor's and master's degrees in engineering from the University of Iowa.
BOM removal during biological treatment: a first‐order model
Authors: Huck Peter M. , Zhang Shulin , Price Michael L.
Published: February 2018

The good linear relationships obtained between influent concentration and removal rate for all parameters tested confirm that removal of biodegradable organic matter during biological drinking water treatment can be approximated by a first‐order model.

Using data from two pilot‐scale studies and one full‐scale investigation, this article demonstrates that the removal rate in biological water treatment is proportional to the influent concentration to the bioreactor, i.e., a first‐order process. This is true not only for measures of biodegradable organic matter, e.g., assimilable organic carbon, but also for precursors of chlorination by‐products such as trihalomethanes. The slope of the removal rate versus the influent concentration relationship is termed the average specific removal rate, rAS. When data were available from different studies, the rAS values tended to fall in the same range. With a first‐order model, the performance of biological treatment in a given situation can be estimated from limited data. The model is suggested as an approach for the preliminary design of bioreactors for drinking water treatment.
Bromide's effect on DBP formation, speciation, and control: part 1, ozonation
Authors: Shukairy Hiba M. , Miltner Richard J. , Summers R. Scott
Published: February 2018

Ozonation of high‐bromide waters at ambient pH will likely result in bromate concentrations that exceed the maximum contaminant level specified in the draft D–DBP Rule.

The effect of variable ozone dosage and bromide concentration on the formation of organic disinfection by‐products (DBPs) and bromate were evaluated. Low ozone dosages resulted in oxidation of organic precursors, yielding decreases in the formation potential for total trihalomethanes (THMs), six haloacetic acids (HAAs), and total organic halide (TOX). Increasing the ozone dosage oxidized bromide to bromate, decreasing the bromide for incorporation into DBPs. Bromate concentrations were linearly correlated with ozone residuals. Changes in the bromine incorporation factors n and n' reflected differences in the resulting speciation of THMs and HAAs, respectively. Because TOX measurements based on chloride equivalence may underestimate the halogenated DBP yield for high‐bromide waters, a procedure is described whereby bromide and bromate concentrations were used to correct the TOX measurement.
Stainless‐steel piping
Authors: Tuthill Arthur H.
Published: February 2018

Stainless‐steel piping can be cost‐effective for potable water use.

Stainless steel has been used extensively for potable water since the mid‐1960s in desalination plants for handling product water; in potable water treatment plants for gravity filtration and piping; in Tokyo, Japan, for small‐diameter household connection piping; and in New York City for large‐diameter risers and other piping. The most familiar use of stainless steel is for drinking fountains. Background information and general data are given on types 304 (UNS S30400) and 316 (S31600) stainless steel, and their current use in potable water applications is reported. The behavior of stainless steel used with raw, chlorinated, and finished water as well as of piping buried in soil is reviewed. Postfabrication cleanup and maintenance of exterior appearance and cleanliness are also reviewed. Guidelines for procurement and successful use are suggested.
Effect of iron oxide coating on sand filtration
Authors: Stenkamp V. Susie , Benjamin Mark M.
Published: February 2018

Although the difference in their efficiencies was frequently small, iron‐oxide‐coated sand outperformed uncoated sand as a filter medium in almost all cases.

Plain sand was compared with iron‐oxide‐coated sand as a medium for filtration. The coated sand has a positive surface charge at neutral pH, whereas uncoated sand is negatively charged under similar conditions. The influent to the filters contained either latex particles, which were negatively charged in all solutions investigated, or ferrihydrite particles, which were negatively charged at pH > 5 but positively charged at lower pH values. The coated medium outperformed the uncoated one in most experiments, a result that is consistent with expected electrostatic interactions.
Health implications of arsenic in drinking water
Authors: Pontius Frederick W. , Brown Kenneth G. , Chen Chien‐Jen
Published: February 2018

Definitive answers regarding arsenic health risks at low exposures will be elusive without additional research.

The adequacy of the current maximum contaminant level (MCL) for arsenic is being evaluated by the US Environmental Protection Agency. If recent theoretical estimates of chronic effects and cancer risks prove accurate, the current MCL may not effectively protect health. Knowledge of arsenic pharmacokinetics and mechanisms in humans, however, is not complete enough to provide a definitive answer, and current epidemiologic evidence is too inconsistent and too fraught with uncertainty regarding arsenic exposure to be helpful in assessing low‐level risks.
Alternative strategies for removing bromate
Authors: Siddiqui Mohamed , Amy Gary , Ozekin Kenan , Zhai Wenyi , Westerhoff Paul
Published: February 2018

For all the potential bromate removal processes evaluated, analysis of the treated water showed the formation of bromide ion, indicating that chemical reduction of the bromate is the primary removal mechanism.

Stage 1 of the Disinfectants–Disinfection By‐Products Rule specifies a maximum contaminant level of 10 μg/L for bromate ion, a by‐product of the ozonation of natural water containing bromide ion. Several options for removing bromate after its formation are evaluated: reduction with ferrous iron (Fe2+), reduction on the surface of activated carbon, ultraviolet irradiation, and high‐energy electron beam irradiation. For all the processes, bromide was found in the treated water, which indicates that the dominating mechanism of bromate removal is chemical reduction. If Fe2+ is introduced after preozonation, it may function both as a reducing agent for bromate and as a coagulant for dissolved organic carbon removal.
Disposal of Radioactive Residuals Requires Careful Planning
Authors: Pontius Frederick W.
Published: February 2018

Radionuclides removed from source waters during water treatment become concentrated in residual liquids and sludges. Disposal options suggested in the US Environmental Protection Agency draft guiance for liquid wastes that contain radioactivity are summarized. Options include direct discharge to surface waters or sanitary sewers and deep well injection. Federal, State, and local rules may apply to utilities seeking to dispose of residuals that contain radionuclides. Characterizing the wastes to be disposed of will define the disposal requirements that must be met.
Selecting membranes for removing NOM and DBP precursors
Authors: Fu Paul , Ruiz Hector , Thompson Ken , Spangenberg Carl
Published: February 2018

A high‐permeability, charged nanofiltration membrane was successfully operated for organics removal under conditions of higher‐than‐normal recovery and flux rate.

A membrane filtration pilot plant was operated for one year to evaluate the removal of natural organic matter and disinfection by‐product precursors from a highly colored groundwater in Orange County, Calif. Two nanofiltration (NF) membranes—a traditional softening membrane and a high‐permeability, charged membrane—were selected for pilot‐scale testing based on bench‐scale tests of eight NF and ultrafiltration membranes. The high‐permeability NF membrane demonstrated superior organics removal at very high recovery and flux. It also allowed most inorganic constituents to pass through. The concentrate of low total dissolved solids reduced inorganic fouling and made concentrate reuse possible. The article also presents preliminary design criteria and a cost opinion for full‐scale treatment facilities.
Soil and Hydrology: their effect on NOM
Authors: Aiken George , Cotsaris Evangelo
Published: February 2018

Soil chemistry, hydrology, and source material affect not only the amount of natural organic matter in an aquatic system but its reactivity as well. They also help water treatment plant operators anticipate problems.

Organic mater derived from different source materials has distinctive chemical characteristics associated with those materials. Interactions among organic matter and the minerals and inorganic constituents in soil can result in the removal and fractionation of organic matter, altering the composition and reactivity of the dissolved orgainc carbon (DOC). Hydrologic conditions define the flow path and control the rate of transport of DOC within the system. The nature, distribution, and reactivity of organic matter in a given system is determinde, to a large extent, by the strength and nature of interactions among the various components of the environment.
Effects of bromide and NOM on by‐product formation
Authors: Najm Issam N. , Krasner Stuart W.
Published: February 2018

Ozone added for disinfection during drinking water treatment reacts with bromide and DOC to form organic and inorganic by‐products, some of which are proven animal carcinogens.

Bromide and natural organic matter in water are known to play a role in the formation of ozonation by‐products. Their exact effect on the production of various ozonation by‐products was examined in this bench‐scale study, which used ranges of bromide and dissolved organic carbon (DOC) concentrations typical of US waters. Results show that bromate and cyanogen bromide formations are a function of bromide and Doc concrentrations, with the effect of bromide being more significant. On the other hand, the formation of aldehydes and ketoacids was proportional to the amount of DOC in the water, but they were largely unaffected by bromide concentration. In addition, the ozone dosage needed to achieve the target ozone residual increased with DOC concentration
An update of the federal drinking water regs
Authors: Pontius Frederick W.
Published: February 2018

The 104th Congress may bring significant reforms to the SDWA as well as to USEPA's drinking water program.

Previous articles (published in the Journal in February 1990, March 1992, February 1993, and February 1994) reviewed the history, content, status, and schedule of regulations mandated by the Safe Drinking Water Act. Current developments related to these rules are presented in this article.
Field evaluation of the GWDR's natural disinfection criteria
Authors: Yates Marylynn V.
Published: February 2018

A virus transport model USEPA is considering generally underpredicted virus concentration at the wells in this study.

The draft proposed Ground Water Disinfection Rule (GWDR) will exempt some public water supply systems from disinfecting if they can demonstrate that adequate “natural disinfection” occurs between potential sources of fecal contamination and wells. One way to determine that is to use a virus transport model such as VIRALT, which was developed for the Office of Ground Water and Drinking Water of the US Environmental Protection Agency. For this study, several sites were examined where virus contamination of groundwater has been documented. The necessary hydrogeologic and microbiological data from these sites were obtained and used as input values for VIRALT. The model's predictions were then compared with the measured virus concentrations in wells at the sites. It was found that the model generally underpredicted the virus concentration at the wells. A sensitivity analysis revealed that the model is extremely sensitive to the value of the virus adsorption coefficient and the virus inactivation rate.
Uncertainties Drive Arsenic Rule Delay
Authors: Pontius Frederick W.
Published: February 2018

The US Environmental Protection Agency (USEPA) is under court order to sign a proposed rule for arsenic by November 30, 1995. The agency recently announced that it will not meet this deadline, citing the need to gather additional information. Development of a National Interim Primary Drinking Water Regulation for arsenic has been delayed several times over the past 10 years because of uncertainties regarding health issues and costs associated with compliance. The early history of development of the arsenic rule has been reviewed. Only recent developments are reviewed here.
Soluble arsenic removal at water treatment plants
Authors: McNeill Laurie S. , Edwards Marc
Published: February 2018

Conventional treatment steps can be extremely effective at removing arsenic.

Arsenic “profiles” were obtained from full‐scale conventional treatment (coagulation, Fe–Mn oxidation, or softening) plants, facilitating testing of theories regarding arsenic removal. Soluble As(V) removal efficiency was controlled primarily by pH during coagulation, by Fe+2 oxidation and Fe(OH)3 precipitation during Fe–Mn oxidation, and by Mg(OH)2 formation during softening. Insignificant soluble As(V) removal occurred during calcite precipitation at softening plants or during Mn+2 oxidation–precipitation at Fe–Mn oxidation plants. The extent of soluble As(V) removal during coagulation and softening treatments was lower than expected. Somewhat surprisingly, during coagulation As(V) removal efficiencies were limited by particulate aluminum formation and removal, because much of the added coagulant was not removed by 0.45‐μm‐pore‐size filters. At one utility, reducing the coagulation pH from 7.4 to 6.8 (at constant alum dose) improved removal of particulate aluminum, thereby enhancing soluble As(V) removal during treatment.
Incorporating externalities in conservation programs
Authors: Jordan Jeffrey L.
Published: February 2018

Internalizing externalities can influence the selection of new water resoures, the extension of existing supply sources, and utility costs and prices.

As water utilities incorporate integrated resource planning in their management processes, it is necessary to incorporate the concept of externalities. This is particularly important as methods evolve of evaluating the costs and benefits of water conservation programs. The purpose of this article is to provide an introduction to the issues surrounding externalities, including their definition, methods of internalizing externalities, and a survey of ways to estimate costs and benefits of externalities. Although most discussions of externalities emphasize negative effects on the environment, this article will illustrate both positive and negative externalities associated with practicing water conservation.
Minimizing chlorate ion formation
Authors: Gordon Gilbert , Adam Luke , Bubnis Bernard
Published: February 2018

Storage tanks that contain liquod bleach should be periodically flushed and cleaned to minimize buildup of a residual chlorate ion concentration.

The treatment of drinking water with either NaOCl or Ca(OCl)2 is a source of chlorate ion (ClO3−) in finished water. In basic solution, liquid bleach (NaOCl) decomposition is a second‐order process. The decomposition of OCl− involves chlorite ion (ClO2−) as a low‐concentration intermediate. The reaction of ClO2− to form ClO3− is a fast process, and the ClO2− in liquid bleach is at a concentration at least 200 times less than the OCl− concentration. The formation of oxygen from decomposing OCl− is a slower side reaction (<10 percent).
Water quality modeling in distribution networks
Authors: Elton Alan , Brammer Lloyd F. , Tansley Neil S.
Published: February 2018

Severn Trent is finding several practical applications for network models related to water quality.

This article reviews the work of Severn Trent Water, a large private‐sector water utility in the United Kingdom, in building and applying computer‐based water quality network models of its distribution systems. This work has involved building several chlorine decay models of systems of differing size, level of detail, and quality of source water. The firm is applying these models in the design of optimized chlorination strategies to improve customer satisfaction while ensuring the maintenance of effective disinfectant residuals. The article also provides several examples of how other water quality–related network models—including models of water age, substance tracking, and source blending—are growing in application within the company as decision support tools for distribution management.
Cryptosporidium: Answers to Common Questions
Authors: Pontius Frederick W.
Published: February 2018

Since 1976, when it was learned that Cryptosporidium could cause disease in humans, people have been aware of the threat of cryptosporidiosis. New attention is being focused on determining and reducing the risk for cryptosporidiosis from drinking water. Answers to frequently asked questions are provided in this article.
Mechanism of Cryptosporidium, Giardia, and MS2 virus removal by MF and UF
Authors: Jacangelo Joseph G. , Adham Samer S. , Laîné Jean‐Michel
Published: February 2018

Protozoan removal was a function of size, whereas virus removal was influenced by physical straining or adsorption, cake layer formation, or the fouling state of the membrane.

Water quality regulations dealing with microbial removal have increased interest in using microfiltration (MF) and ultrafiltration (UF) as barriers against protozoan cysts and viruses. Consequently, a study was conducted to evaluate the removal of these organisms by a variety of MF and UF membranes and to elucidate removal mechanisms. All of the hollow‐fiber membranes evaluated removed Giardia muris cysts and Cryptosporidium parvum oocysts to below detection limits. No cysts or oocysts were detected in the permeate as long as the membrane remained intact. Physical straining of these organisms from the feedwater appeared to be a primary mechanism of action. The extent of virus removal was membrane‐specific, with removals ranging from <0.5 log to >6 logs. Three phenomena appeared to contribute to virus removal: physical sieving or adsorption, cake layer formation, and fouling state of the membrane. The relative contribution of each of these was a function of water quality, time of operation or filtration, and membrane characteristics.
Bromate ion formation: a critical review
Authors: Siddiqui Mohamed S. , Amy Gary L. , Rice Rip G.
Published: February 2018

Bromate, which forms upon ozonation of water containing bromide ion, can be minimized before production by chemical or physical–hydrodynamic factors or after its formation by removal techniques.

As utilities consider changing their primary disinfection practices from free chlorine to ozone in order to minimize the formation of chlorinated disinfection by‐products (DBPs), the potential for producing ozonation DBPs such as bromate ion must be addressed. Important research findings of bromate ion formation studies over the past five years, which have resulted in substantial understanding of ozone‐bromide ion interactions, are summarized. Areas of incomplete information are identified, and a complete list of references is provided.
Bromide's effect on DBP formation, speciation, and control: part 2, biotreatment
Authors: Shukairy Hiba M. , Miltner Richard J. , Summers R. Scott
Published: February 2018

Both bromo‐ and chloro‐substituted disinfection by‐products decreased significantly when a combination of ozonation and biotreatment was used.

The effect of bromide concentration, ozone dosage, and biotreatment on the control of disinfection by‐products (DBPs) was evaluated. Although total trihalomethane precursors were better controlled by ozonation and the precursors of six haloacetic acids were better controlled by biological treament, the combined processes were effective for the control of all halogenated DBP precursors. Ozone's conversion of bromide to bromate and the chemical or biological oxidation of organic matter changed the ratio of bromide to dissolved organic carbon. Increases in this ratio increased the formation of some brominated DBPs, but these DBP increases were offset by the precursor oxidation provided by the combination of the two processes.
Jar‐test evaluations of enhanced coagulation
Authors: Krasner Stuart W. , Amy Gary
Published: February 2018

Utilities should begin evaluating the amenability of their water supplies to enhanced coagulation.

The proposed Disinfectants/Disinfection By‐Products (D/DBP) Rule includes a requirement that surface water systems using conventional treatment must remove DBP precursors—as measured by total organic carbon (TOC)—in addition to meeting standards for the D/DBPs themselves. TOC removal criteria are based on influent TOC and alkalinity (referred to as step 1); however, systems can demonstrate the need for alternative TOC removal performance criteria based on jar‐testing (referred to as step 2). Tests based on various source waters throughout the United States show that some waters will be able to meet step 1 TOC removal criteria and that although step 2 analysis is not required, jar testing can be used to determine means of complying with the DBP precursor removal criteria. In other waters, however, jar tests will be needed to determine a point of diminishing returns (i.e., <0.3 mg/L TOC removal for an incremental dose of 10 mg/L alum) that can be employed in requesting alternative TOC removal performance criteria.
Setting Standards: Legislative Proposals
Authors: Pontius Frederick W.
Published: February 2018

This article, second of a two‐part series examining the standard‐setting process (part 1 was published in the July 1995 issue), reviews legislative proposals that would change the way drinking water standards are set.
Capital needs of small systems
Authors: Fraser Dan , Davies Clive , Jones Ralph T.
Published: February 2018

Many small systems face significant capital investment needs.

Over the past two years, the US Environmental Protection Agency (USEPA) has conducted the first national survey of the infrastructure needs of community public water supplies. As a part of this survey, USEPA personnel and contractors visited more than 600 small systems to assess capital needs. Small systems were visited in every state, Puerto Rico, the US Virgin Islands, and Pacific Islands. Native American systems and Alaska Native villages were visited as well. A preliminary analysis of the site visits indicates that (1) many small systems face significant capital improvement needs, (2) small system capital needs often arise as a result of substandard design and construction, and (3) most needs of small systems are associated with potential acute health
Traveling Water Screens handling heavy debris
Authors: Sarrouh Sami F. , Ramadan Nagah
Published: February 2018

In Cleveland, upgraded screens are tolerating the increased weight from zebra mussels.

Traveling water screens were originally designed to be barriers against minimal debris and to have low differential heads. However, because of changing ecological conditions, the screens are collecting much heavier loads of debris, including zebra mussels. In many installations, the screens must be structurally and mechanically enhanced to meet the new requirements. In this article, the authors recommend several measures that greatly improve the reliability and performance of traveling water screens. In addition, they propose major design changes manufacturers could make, and they propose that an AWWA standard for traveling water screens is needed.