bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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.
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.
Conservation in the Delaware River Basin
Authors: Featherstone Jeffrey 
Published: February 2018

In the Delaware River Basin, an ambitious water conservation program is resulting in cost savings, improved drought preparedness, and environmental protection.The Delaware River Basin Commission (DRBC) has embarked on an ambitious water conservation program to reduce the demand for water. Conservation has become an integral component of the commission's strategy to manage water supplies in the four‐state Delaware River Basin. The program includes both regulatory and educational initiatives. DRBC has adopted five conservation regulations, which pertain to source metering, service metering, leak detection and repair, water conservation performance standards for plumbing fixtures and fittings, and requirements for water conservation plans and rate structures. DRBC also sponsors information and education events, such as symposiums on selected topics and water conservation technology transfer sessions with major industrial and commercial groups.
Conservation and the industrial customer
Authors: Ploeser Jane H. 
Published: February 2018

Marketing conservation to industrial customers requires a different approach.Obvious differences between nonresidential and residential water customer markets call for a different marketing program for industrial, commercial, and institutional sectors. Although basic marketing tenets must be adhered to, the strategies are more complex, the communications are more vertical, and the message focuses more on costs and return on investment than on ethical or environmental sensibilities.
Flow trace analysis to access water use
Authors: DeOreo William Butler , Heaney James Patrick , Mayer Peter W. 
Published: February 2018

Analyzing flow traces from residential water meters enabled researchers to collect precise data about water use by individual fixtures.Precise information about water use patterns can be gathered by analyzing flow traces obtained from residential customer water meters that are fitted with portable data loggers. Flow traces are precise enough that signatures associated with all major water use categories can be identified. For this study, more than 10,000 water use events were recorded, classified, and entered into a database. The technique is both accurate and reliable and can be used to collect time‐specific and disaggregated water use data. Measuring directly instead of inferring measurements from aggregated data is a quick and cost‐effective way to analyze water use patterns and directly assess how conservation measures influence water demand
Cool‐season turfgrass: estimating water use
Authors: Kerr Greg , Pochop Larry , Teegarden Travis 
Published: February 2018

With these coefficents, engineers can estimate evapotranspiration and water needs for turfgrass.Consumptive‐use coefficients for cool‐season turfgrass have been developed using the Penman‐Monteith and United Nations Food and Agriculture Organization Blaney‐Criddle equations. Transferability of these evapotranspiration (ET) equations to regions of varying climatic conditions is greater than that of the original temperature‐based Blaney‐Criddle equation, for which turfgrass coefficients were previously developed. The coefficients provide practicing engineers with information that permits the conversion of ETr to ETcrop for cool‐season turfgrass using data for the complete range of climatic parameters available from sources such as the Automated Surface Observing System of the National Weather Service. The ETcrop values represent the water required of city water systems.
Water supply implications of herbicide sampling
Authors: Stamer John K. 
Published: February 2018

Hydrologic conditions may affect concertrations of organonitrogen herbicides and may be important considerations in complying with drinking water regulations.The temporal distribution of the herbicides alachlor, atrazine, cyanazine, and metolachlor was documented from September 1991 through August 1992 in the Platte River at Louisville, Neb., the drainage of the Central Nebraska Basins. Lincoln, Omaha, and other municipalities withdraw groundwater for public supplies from the adjacent alluvium, which is hydraulically connected to the Platte River. Data were collected, in part, to provide information to managers, planners, and public utilities on the likelihood of water supplies being adversely affected by these herbicides. Three computational procedures—monthly means, monthly subsampling, and quarterly subsampling—were used to calculate annual mean herbicide concentrations. When the sampling was conducted quarterly rather than monthly, alachlor and atrazine concentrations were more likely to exceed their respective maximum contaminant levels (MCLs) of 2.0 μg/L and 3.0 μg/L, and cyanazine concentrations were more likely to exceed the health advisory level of 1.0 μg/L. The US Environmental Protection Agency has established a tentative MCL of 1.0 μg/L for cyanazine; data indicate that cyanazine is likely to exceed this level under most hydrologic conditions.
Siting a large GAC regeneration facility
Authors: Liang Sun , Welch Daniel K. , Owen Douglas M. , Beuhler Mark D. 
Published: February 2018

Researchers at a large Southern California utility considered hazardous waste and air quality regulations as well as public concerns, space allocations, and estimated costs.In anticipation of future disinfectant/disinfection by‐product regulations, the Metropolitan Water District of Southern California has evaluated the issues associated with siting a large granular activated carbon (GAC) regeneration facility in Southern California. This study identified significant issues related to GAC regeneration, including process criteria, air quality effects, management of spent GAC, space constraints and costs, and public acceptance.
Competitive ways to run water utilities
Authors: Westerhoff Garret P. , Lane Thomas J. 
Published: February 2018

As utilities consider more competitive ways to improve service and reduce costs, the overall objective of public health protection must be kept in the forefront.In recent years drinking water utilities have faced increasingly difficult challenges in their role of protecting public health and providing affordable drinking water of adequate quality and quantity. This requires a continuing search for new and more efficient ways to provide service. Some utilities are considering contracting out certain elements of their operations to private firms. Another efficiency may be to increase the competitive position of the public utility itself. The healthiest situation may be for both public and private approaches to exist within the industry and provide ongoing competition.
Adsorption kinetics of MIB and geosmin
Authors: Huang Chih , Van Benschoten John E. , Jensen James N. 
Published: February 2018

Well‐established and alternative modeling approaches involving the homogeneous surface diffusion model were used to investigate several parameters.The kinetics of 2‐methylisoborneol (MIB) and geosmin are examined using laboratory and field data and through model simulations using the homogeneous surface diffusion model (HSDM). Both the laboratory and field data indicate that adsorption kinetics for MIB are slow and that equilibrium may not be reached when powdered activated carbon is used, even with relatively long contact times (4–6 h). Isotherm predictions of field‐scale data were lower than measured data, indicating possible kinetic limitations. Model parameters for the HSDM were based on equilibrium isotherm data, laboratory kinetic experimental data, or both. The simplest approach involved fitting all model parameters to kinetic data. Fitted isotherm parameters compared well with independent isotherm study data. Simulated field‐scale effluent MIB concentrations showed good agreement with measured data. The modeling approaches used are easy to implement compared with previous approaches based on ideal adsorbed solution theory and the HSDM.
Effect of ozone on EOM and coagulation
Authors: Paralkar Ashish , Edzwald James K. 
Published: February 2018

Extracellular organic matter from algae affects particle coagulation, depending on the type of algae and the concentration of the extracellular matter.Ozonation of drinking water containing algae sometimes produces beneficial effects on coagulation. These benefits are often attributed to the extracellular organic matter (EOM) from the algae. This study focused on the properties of extracted EOM from three species of algae. Ozonation of EOM reduced its apparent molecular size and hydrophobicity. Ozonation also increased the functional group charge of EOM compounds but decreased the charge as measured by the colloid charge titration. Coagulation experiments with extracted EOM indicated that only small amounts were necessary to neutralize positively charged latex particles. Ozone produced no significant effect on EOM and thus did not affect coagulation of these particles. Alginic acid, a model EOM compound, was compared with the extracted EOM and behaved similarly to the high‐molecular‐size extracted EOM.
Regulations governing membrane concentrate disposal
Authors: Pontius Frederick W. , Kawczynski Elizabeth , Koorse Steven J. 
Published: February 2018

All relevant regulations must be considered during planning.Membrane concentrate disposal is regulated under several federal laws, and state and local governments may impose additional requirements. Regulatory requirements are complex and, in many cases, the federal–state–local regulatory maze can be perplexing. The method or methods used for membrane disposal determine which regulatory requirements must be met. A comprehensive regulatory compliance strategy ensures that the appropriate permitting and other regulatory requirements are met. With careful planning, membrane concentrate disposal can be done in an environmentally acceptable way that satisfies all regulatory requirements.
Organics in NF permeate
Authors: Agbekodo Koffi Marcus , Legube Bernard , Coté Pierre 
Published: February 2018

Nanofiltration yields high‐quality drinking water at a treatment plant in the Paris suburbs.The removal of dissolved organic carbon (DOC) and biodegradable dissolved organic carbon (BDOC) is one of the most important means of reducing total organohalide formation potential and bacterial regrowth in distribution networks. A nanofiltration operation in a Paris suburb, in use at industrial scale for more than a year, has proved an excellent technology to meet new guidelines for chlorine disinfection by‐products and to produce high‐quality drinking water. In the laboratory, amino acids and sugars were identified as the main organic constituents of the permeate, which is low in DOC, BDOC, and total organic halide precursors.
Reducing cancer risks by improving organic carbon removal
Authors: Black Bryan D. , Harrington Gregory W. , Singer Philip C. 
Published: February 2018

A computer simulation methodology evaluated the risk‐reduction benefits of improving organic carbon removal prior to chlorination.A computer simulation methodology is described that examines on a case‐specific basis the effect of water quality on the formation of trihalomethanes (THMs) and their associated theoretical cancer risks. The strategy of controlling organic carbon concentrations at the point of chlorination was evaluated for its ability to reduce predicted cancer incidence. In waters containing bromide, the absolute concentrations of the more brominated THMs can increase as organic carbon concentration is reduced at the point of chlorination; total theoretical cancer risks induced by THMs, however, decreased for all water qualities considered. Reduction of THM‐induced cancer risks by enhanced coagulation, granular activated carbon adsorption, and membrane filtration increased as the source water bromide concentration increased. When risks induced by haloacetic acids are considered, these technologies may achieve significantly greater levels of risk reduction than are estimated by considering THM risks only.
Bromate formation in advanced oxidation processes
Authors: von Gunten Urs , Bruchet Auguste , Costentin Eliane 
Published: February 2018

When conventional ozonation processes are replaced by a combination of ozone and hydrogen peroxide, bromate formation increases when the ozone residual is kept constant but decreases when the ozone dose is kept constant.Bromate formation in conventional ozonation and advanced oxidation processes combining ozone and hydrogen peroxide was investigated at five water treatment plants. Before ozonation, bromide concentrations ranged from 35 to 130 pg/L. Bromate formed during the ozonation step varied from <2 to 42 μg/L. In general, advanced oxidation leads to higher bromate concentrations when compared with a conventional ozonation process, if the same ozone residual is maintained for both processes. Lower concentrations result if the ozone dosage is kept constant and the hydrogen peroxide dosage is increased.