bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimizing enhanced coagulation with PAC: A case study
Authors: Najm Issam , Tate Carol , Selby Douglas 
Published: February 2018

Enhanced coagulation plus PAC achieves required NOM removals at minimum cost.Enhanced coagulation can remove only a finite fraction of the natural organic matter (NOM) in water. Supplementing enhanced coagulation with powdered activated carbon (PAC) increases the removal of NOM and disinfection by‐product (DBP) precursors. The removal of total organic carbon (TOC) and DBP precursors from Colorado River water was evaluated in an experimental matrix of jar tests using four ferric chloride dosages and four PAC dosages. On the basis of the chemical dosages used, the cost of each combination of coagulant and PAC addition was estimated. For a given TOC removal goal, a particular combination of ferric chloride and PAC dosages resulted in the lowest chemical costs. The analysis also indicated that this same dosage combination would produce the least sludge at the water treatment plant. This study shows that the combination of a chemical coagulant and PAC can be more cost‐effective than a chemical coagulant alone for meeting the requirements of Stage 1 of the Disinfectants/DBP (D/DBP) Rule. In addition, the combination of a chemical coagulant and PAC may be a cost‐effective alternative to granular activated carbon for meeting the requirements of Stage 2 of the D/DBP Rule.
Committee Report: Gasket materials
Authors:   AWWA Committee on Gasket Materials for Water Works Service
Published: February 2018

Elastomers' use‐specific sensitivity to chloramine makes it difficult to develop test methods, pass‐fail criteria, and a standard appropriate for all rubber components.Rubber components are used extensively in water distribution systems, and their long‐term performance is of concern to water utility engineers. Thus, AWWA member utilities asked the AWWA Research Foundation (AWWARF) to investigate how chlorine and chloramine affect these components. In 1992, AWWARF commissioned a study to evaluate the effects of chlorinated and chloraminated water on two types of elastomers: generic specimens of known formulations and sheet stock of unknown formulations. This report responds to the AWWARF research, which concluded that chloraminated waters are more detrimental to most elastomers than waters with equivalent concentrations of chlorine. It also enumerates proposed actions, including developing pass‐fail criteria, related to these findings and explains why it is not currently feasible to develop an AWWA standard for all gaskets used in chloraminated waters.
Safeguarding distribution system integrity
Authors: Trussell R. Rhodes 
Published: February 2018

Keeping a residual is important, but it is only one of many actions needed to safeguard the integrity of the distribution system.When water utilities began using chlorine for primary disinfection, a residual in the distribution system came with it. Regulations have made the distribution system residual an increasingly important requirement in many parts of the world. However, many groundwater systems commonly operate without a residual, and several European utilities now operate with no residual in treated surface water. This article examines the reasons often cited for maintaining a disinfectant residual and discusses the merits of alternative residual disinfectants.
US regulations on residual disinfection
Authors: Shaw Susan E. , Regli Stig 
Published: February 2018

Preserving distribution system water quality and protecting public health depend on regulations as well as a whole‐system approach.Most community water systems in the United States disinfect their water. However, only surface water systems are currently required to provide a disinfectant residual in the distribution system. This article reviews existing regulations, including the Surface Water Treatment Rule and the Total Coliform Rule, for maintaining a disinfectant residual and outlines their requirements. It also discusses forthcoming and long‐term regulations and how they may affect water treatment and distribution system water quality, operations, and maintenance.
ICR protocol: alternative treatment of parasite sample data
Authors: Atherholt Thomas B. , Korn Leo R. 
Published: February 2018

Alternative data analysis and reporting methods may help avoid flaws inherent in the current ICR protocol.As part of the Information Collection Rule (ICR), the US Environmental Protection Agency (USEPA) has specified an immunofluorescence assay protocol for handling and reporting Giardia cyst and Cryptosporidium oocyst data. The protocol is flawed in several respects, primarily the extrapolation of cyst and oocyst counts in a small “equivalent sample volume” analyzed to a 100‐L volume, the conversion of zero counts to less than one count, and the reporting of the data collected in this manner. Such data conversion and reporting can introduce data analysis problems. USEPA's draft method 1622 for analyzing water samples for Cryptosporidium does not specify how parasite count data should be treated or analyzed. If ICR method data handling and reporting specifications are followed, parasite concentration data obtained using method 1622 could also be inaccurate. The authors propose an alternative procedure for analyzing and reporting ICR parasite data.
Capacity development: the small system perspective
Authors: Soelter Alan D. , Miller Ellen G. 
Published: February 2018

A sampling of state agencies and midsized and small systems uncovered concerns about capacity development provisions and suggestions for resolving these concerns.A brief two‐part study was undertaken to find out what midsized and smaller systems know about capacity development and what they need in order to comply with SDWA requirements. Three paradoxes emerged. (1) Capacity development provisions bring both more risk and more opportunity. (2) The provisions take more time but also save time. (3) The provisions allow states flexibility while requiring them, as a condition of receiving 100 percent of their Drinking Water State Revolving Fund allotment, to help systems acquire and maintain capacity. Suggested steps to resolve these paradoxes are presented for consideration by state primacy agencies and other groups.
Benefit–cost analysis of the Stage 1 D/DBP Rule
Authors: Odom Rosemarie , Regli Stig , Messner Mike , Cromwell John , Javdan Maggie 
Published: February 2018

Protecting the public from exposure to DBPs and the subsequent risk of certain cancers must be balanced with controlling water treatment costs.In 1992–93, the US Environmental Protection Agency (USEPA) convened a negotiated rulemaking process under the Federal Advisory Committee Act (FACA) to develop a consensus approach to simultaneously addressing potential health risks posed by disinfection by‐products (DBPs) and waterborne pathogens. The fact that inadvertent risk–risk tradeoffs might be made between protection from DBPs and protection from microbial pathogens complicates the process. It is further complicated by uncertainties that affect the assessment of both risks. The regulatory‐negotiations committee devised a staged approach to regulation that a second FACA committee finalized in 1996–97. This article summarizes the DBPs side of the benefit–cost analysis that was developed during these processes and later refined by USEPA to more fully address uncertainties regarding the rule's benefits.
Uses of protozoan monitoring data
Authors: Clancy Jennifer L. , Hansen Judi 
Published: February 2018

Utilities around the world monitor for pathogens, but many find the data too unreliable to be used as a basis for making water quality or public health decisions.European and North American water utilities and regulatory agencies were surveyed to determine current drinking water monitoring practices for Giardia cysts and Cryptosporidium oocysts and to ascertain how the monitoring data are used. Responses from 27 agencies indicated that monitoring is still generally voluntary, except in the case of disease outbreaks, during which regulatory agencies can require testing. The data are used to study the occurrence of protozoa in source water, to assess treatment efficiency, and to support investment planning. Rarely are these data used to make public health decisions and then only in conjunction with other data such as weather–watershed changes, treatment information, other water quality parameters (i.e., turbidity), and presence of disease in the community. The primary reason protozoan monitoring data are not used in public health decision‐making is lack of reliability of the data quality.
Potable use of reclaimed water
Authors: Crook James , MacDonald Jacqueline A. , Trussell R. Rhodes 
Published: February 2018

Indirect potable reuse is a viable application of reclaimed water if indicated by site‐specific assessments that include contaminant monitoring, health and safety testing, and system reliability evaluation.The National Research Council released a report in 1998 that evaluated the feasibility of augmenting drinking water supplies with highly treated reclaimed water. The report concluded that indirect potable reuse of reclaimed water (i.e., using reclaimed water to augment a potable water source before treatment) is viable and that direct potable reuse (i.e., introducing reclaimed water directly into a water distribution system) is not viable. Although recent health‐related research has uncovered no adverse effects, such health data are sparse, and the methods for such research are limited. Consequently, the results cannot be extrapolated to potable reuse in general. Thus, each indirect potable reuse project should be implemented only after a thorough, project‐specific assessment of health concerns and measures to mitigate them. Finally, potable reuse should only be considered in communities in which other efforts—water conservation, development of new water sources, and nonpotable reuse—cannot cost‐effectively meet the communities' needs. This article describes the council's recommendations for ensuring the safety of water systems that augment raw water sources with reclaimed water.
Setting reclaimed water rates
Authors: Cuthbert Richard W. , Hajnosz Ann M. 
Published: February 2018

Reasonable rates play a large role in encouraging public support for a reclaimed water system.The use of reclaimed water to offset potable water demands is becoming more popular. Setting reclaimed water rates and charges is an important factor in establishing and operating a reclaimed water system. This process is complex because it often costs more to provide reclaimed water than it does to provide potable water even though reclaimed water is generally of lower quality. The long‐term benefits of reclaimed water, however, are significant enough that most utilities want to encourage its use. To illustrate how a utility should price reclaimed water in order to encourage its use, this article summarizes results of a survey of rates and pricing strategies used by 23 US utilities that operate reclaimed water systems. In addition, strategies for setting reclaimed water rates are discussed based on a case study developed for the city of Tucson, Ariz., Water Department. In some circumstances, sound economic justifications exist for pricing reclaimed water below its embedded cost‐of‐service level.
Reduction of bromate in a BAC filter
Authors: Kirisits Mary Jo , Snoeyink Vernon L. 
Published: February 2018

Water treatment plants already using ozone and GAC filters can readily implement this method of removing bromate.Bromate removal was observed during biologically active carbon (BAC) filtration. Microorganisms in the BAC reduced bromate to bromide, although the formation of other intermediate species is possible. The effects of dissolved oxygen (DO) concentration, nitrate concentration, and empty bed contact time (EBCT) on microbial bromate reduction were examined. Oxygen and nitrate, common microbial electron acceptors, hindered bromate reduction. For example, at an influent DO concentration of 2 mg/L in a BAC filter with a 25‐min EBCT, bromate was reduced by 86 percent at an influent nitrate concentration of 0.2 mg/L, whereas it was reduced by 76 percent at an influent nitrate concentration of 5.1 mg/L. In general, lengthening the EBCT increased bromate removal. Biological bromate removal in a conventional ozone–granular activated carbon plant was deemed possible if the DO concentration in the BAC filter is controlled.
Effect of filter media on cyst and oocyst removal
Authors: Swertfeger Jeff , Metz Deborah H. , DeMarco Jack , Braghetta Anne , Jacangelo Joseph G. 
Published: February 2018

Spiking studies underscore the important role filtration plays in removing protozoa from surface water.As part of a pilot‐scale examination of filtration media at the Cincinnati (Ohio) Water Works, heat‐inactivated Giardia cysts and Cryptosporidium oocysts were spiked into surface water that had already undergone coagulation and sedimentation. This spiked water was then introduced into pilot‐scale filters containing sand only, typical dual anthracite–sand, and deep dual anthracite–sand media configurations. All of the media types used in this study demonstrated similar removal capabilities, with average cyst removal ranging from 2.7 to > 4.5 logs and average oocyst removal of 2.7–3.9 logs. Endospore and polystyrene bead removals were similar to those of the protozoa, but turbidity and particle counts demonstrated substantially less removal capability.
Water utilities as integrated businesses
Authors: Heller Miriam , Von Sacken Eric W. , Gerstberger Richard L. 
Published: February 2018

Information technology is helping utilities achieve a competitive edge today and move closer to ecoefficiency.With privatization, managed competition, deregulation of the power industry, and increasing environmental legislation, water utilities must aspire to more than high levels of service and reliability. They must seek competitive levels of service and reliability. To reach this goal, water providers have to balance financial considerations and consumer requirements. They must make optimal use of production processes and support systems, ultimately achieving ecoefficiency, i.e., economically efficient use of resources with other businesses. Information technology (IT) plays a key role in achieving this climate of widespread efficiency by (1) enabling the integration of computer systems, information, human resources, and natural resources; (2) defining common performance measures; and (3) optimizing performance. Three existing paradigms—the utility communications architecture, utility business architecture, and industrial ecology—can serve as structured applications for efficient IT planning and deployment at the plant, utility, and regional levels.
Sizing residuals drying beds
Authors: Cornwell David A. , Vandermeyden Carel 
Published: February 2018

Pilot tests and this design model can correctly size nonmechanical dewatering processes.Design criteria were developed for nonmechanical dewatering of water treatment residuals. First, certain physical properties were determined for residuals high in alum, ferric chloride, or polyaluminum chloride. Laboratory tests that characterized these properties showed that capillary suction time and time to filter correlated very well; either could be used in the laboratory to test residuals' drainage characteristics. Pilot‐ and full‐scale evaluations at five utilities followed. Drainage characteristics predicted by pilot tests using 2‐in.‐ (50‐mm‐) diameter columns and measured in full‐scale sand drying beds correlated closely. This work showed that pilot tests can allow good prediction of full‐scale performance and, thus, the development of useful design parameters. Three models illustrate the proper sizing of sand drying beds, solar drying beds, and dewatering lagoons. These models allow a utility to determine the area required for each dewatering method on the basis of pilot data, local climatological data, and—most important—monthly residuals production. This article presents the test procedures and modeling required for utilities to size and design nonmechanical dewatering systems.
Rehabilitation of 1940s water mains
Authors: Hall Bruce B. 
Published: February 2018

In‐place relining of rusted water mains restored aesthetically high‐quality water.Water District No. 1 of Johnson County, Kan., rehabilitated sections of unlined cast‐iron pipe installed in the 1940s. Customers complained to the district about rusty water delivered to their homes. After two options were investigated, the cast‐iron pipes and fittings were cleaned and lined in place with cement mortar. The water district and the customers that it serves are both pleased with the result: elimination of rusty water at a reasonable cost.
Occurrence of MTBE in drinking water sources
Authors: Gullick Richard W. , LeChevallier Mark W. 
Published: February 2018

A recent survey investigates the prevalence of MTBE in drinking water supplies and evaluates the efficacy of treatment for MTBE removal.Methyl tertiary butyl ether (MTBE) is of concern to the drinking water supply profession because of its strong taste and odor effects, potential risk to human health, tendency to migrate rapidly in groundwater, and resistance to conventional water treatment processes. An occurrence survey was performed from 1997 to 1998 to assess the prevalence of MTBE in surface and subsurface drinking water supplies. The survey examined 342 wells in 17 states, and MTBE was detected at least once in 30 wells (~8.8 percent). All samples were below the US Environmental Protection Agency's taste and odor advisory level of 20 μg/L. In addition, 92 surface water sites in 12 states were evaluated, and MTBE was detected at least once at eight sites (~8.7 percent). The highest concentration (25.1 μg/L) was detected downstream from a known gasoline release. Aeration removed up to 76 percent of low concentrations of MTBE, but activated carbon adsorption was relatively ineffective.
Use of polyphosphate in corrosion control
Authors: Cantor Abigail F. , Denig‐Chakroff David , Vela Richard R. , Oleinik Mark G. , Lynch Daniel L. 
Published: February 2018

Case studies from three Wisconsin utilities found that polyphosphate blends used for corrosion control led to increased metal concentrations in the water.When polyphosphate blends are added to water systems under certain conditions, leaching of pipe metal into the water may be significantly increased rather than decreased. Case studies of three Wisconsin water utilities uncovered possible negative consequences of using polyphosphate for corrosion control. These experiences suggest that water providers must exercise caution when adding polyphosphate to drinking water systems. Utilities should conduct off‐line tests before using polyphosphate, and full‐scale systems should be frequently monitored after polyphosphate addition. More research is needed to define the proper use of polyphosphates and to investigate alternatives to polyphosphates.
Removing arsenic from groundwater
Authors: Chwirka Joseph D. , Thomson Bruce M. , Stomp John M. 
Published: February 2018

To meet the new arsenic MCL, Albuquerque, N.M., will construct its first arsenic treatment facility.Three treatment technologies for removing arsenic from groundwater in Albuquerque, N.M., were compared: ion exchange (IX), iron hydroxide coagulation followed by microfiltration (C/MF), and activated alumina (AA) adsorption. For an 8,700‐m3/d (2.3‐mgd) arsenic treatment facility, capital costs of the three processes were similar: $5.2 million, $4.1 million, and $4.6 million, respectively. Annual operations and maintenance costs were $447,000, $273,000 and $444,000, respectively. The principal differences were the result of large salt requirements for the IX process and the need to reduce the pH to 6 for AA adsorption, followed by base addition to stabilize the water. The C/MF system was selected for a demonstration facility in Albuquerque.
Freeze‐thaw residuals conditioning
Authors: Parker Philip J. , Collins Anthony G. , DeWolfe James R. 
Published: February 2018

Freeze–thaw conditioning can reduce residuals disposal costs.Freeze–thaw conditioning is an effective way to process water treatment residuals. For many years the process has used natural out‐of‐doors freezing, but development of mechanical processes has been hindered by a lack of fundamental information about the process. This article presents the results of experiments performed to study the effects of initial solids content, curing time, and freezing rate on dewaterability of residuals from five water treatment facilities in the northeastern United States. Dewaterability of all residuals sharply increased following freeze–thaw conditioning. In the experimental procedure used, dewaterability following freezing and thawing was independent of rate. However, initial solids content and curing time strongly affected dewaterability, which was best for residuals frozen at high solids content and cured for long times. Cake solids contents > 40 percent w/w were achieved. Generally, the process was most successful for residuals that exhibited the best dewaterability before freeze–thaw conditioning. Finally, cost‐optimum freezing conditions were determined.
Energy indicators and savings in water supply
Authors: Pelli T. , Hitz H.U. 
Published: February 2018

Indicators that are easy to apply can assess the efficiency of energy usage.This article describes two indicators that evaluate the energy consumption of a water supply system. The structure indicator describes how the spatial distribution of users and water sources influences energy consumption. It is defined as the minimal energy that is necessary to lift a cubic metre of water to users and to give it a pressure of 6 bar (88 psi), a typical water pressure at the tap. In turn, minimal energy can be calculated as the difference between the potential energy of the delivered water (for some unit of time) and the potential energy of the same quantity of water at the source. The quality indicator is defined as the ratio of the effective energy used (during the same unit of time) and minimal energy. It shows the efficiency of the entire water supply system, which is determined by factors such as the efficiency of pumps, locations of reservoirs, and water loss in the network. The results of calculations are used to establish a relationship between the value of the quality indicator and the energy‐reduction possibilities; this relationship permits a water supplier to evaluate how economically a water supply system uses its energy.
Insurance issues surrounding pipe‐related liabilities
Authors: Sylvester John M. , Reiter Thomas M. , Waldron John T. 
Published: February 2018

Court decisions and other weapons in the legal arsenal can help policyholders obtain coverage and avoid exclusions for pipe‐related liabilities.When a plumbing system fails and causes damage, pipe‐related liabilities can affect numerous policyholders, from pipe manufacturers, designers, and installers to public and private users of the product. The authors examine a number of coverage issues raised by insurers in response to claims related to pipe liability. These questions include when coverage is triggered and which insurers are liable for pipe problems that develop over many years. In addition, the authors detail arguments that policyholders can use to defeat the principal exclusions raised by insurers and describe the recourses available to compel insurers to cover pipe‐related liabilities. Although a final determination of coverage ultimately depends on the specific language of the policy and underlying facts of each case, many of the defenses and limitations raised by insurers can be overcome if policyholders vigorously pursue their rights to coverage.