bluuebunny/crossref_metadata_2025 huggingface dataset:
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.
Three approaches for characterizing NOM
Authors: Krasner Stuart W. , Croué Jean‐Philippe , Buffle Jacques , Perdue E. Michael
Published: February 2018

These techniques yield valuable insights into complex natural organic matter.

Three research approaches to characterize natural organic matter (NOM) are available: (1) a nonperturbing approach, (2) an approach based on isolation–fractionation, and (3) an approach based on calculations. A nonperturbing approach has been used to assess the aromaticity and morphology of NOM. Characterization of isolated fractions has shown that the two main fractions—fulvic and hydrophilic acids—are in some points structurally different. Furthermore, reasonable estimates of several structural features of NOM have been obtained by analytical‐constraints calculations. Each approach yields valuable insights into NOM—its source and nature in watersheds, how seasonal variations affect it, and its potential to form disinfection by‐products. Each approach also yields insight into the relationship between NOM's structural and compositional properties.
Go to Letter: Lead and Copper Rule Revisions Proposed
Authors: Pontius Frederick W.
Published: February 2018

Regulations for lead and copper were promulgated by the US Environmental Protection Agency (USEPA) June 7, 1991. On April 12, 1996, the agency proposed minor revisions to these regulations in order to streamline implementation and reduce reporting burdens. The proposed changes do not affect basic regulatory requirements but are intended to make implementation easier and to reduce costs. The notice also requested comment on several measures that the agency is considering to further ease the implementation burden. The proposed revisions are reviewed in this paper.
Hydraulic mixing and free chlorine residual in reservoirs
Authors: Boulos Paul F. , Grayman Walter M. , Bowcock Robert W. , Clapp Jonathan W. , Rossman Lewis A. , Clark Robert M. , Deininger Rolf A. , Dhingra Ashok K.
Published: February 2018

Interior sampling of a reservoir illuminates its mixing characteristics and supports the assumption of stratification or partitioning.

An extensive sampling study of reservoir water quality was conducted in Azusa, Calif. Primary emphasis was placed on providing a better understanding of the dynamics of hydraulic mixing and free chlorine residual concentration distribution in the reservoir. The reservoir approached completely mixed behavior with two exceptions: a degree of short‐circuiting between the inlet and outlet (which significantly affected the T10 time) and the presence of a stagnant zone in the center core of the reservoir where there was less mixing and thus older water. These results support the assumption of stratification or partitioning in reservoirs. Regular field sampling is recommended to facilitate the effective management of distribution system water quality. In particular, interior sampling of reservoirs can provide useful information that could not be inferred otherwise.
Occurrence of nitrification in chloraminated distribution systems
Authors: Wilczak Andrzej , Jacangelo Joseph G. , Marcinko Joseph P. , Odell Lee H. , Kirmeyer Gregory J.
Published: February 2018

Data from US distribution systems that chloraminate are evaluated as predictors of nitrification.

Utilities in the United States that chloraminate were surveyed to evaluate the incidence of nitrification in distribution systems and determine whether nitrification can be predicted from basic system and water quality data. An estimated two thirds of medium and large US systems that chloraminate experience nitrification to some degree. About every fourth surveyed utility reported moderate to severe nitrification problems. In addition, every fourth utility did not know the extent of nitrification in its system. The incidence of nitrification was more frequent during summer or when the temperature was greater than 15°C (59°F); nevertheless, several sites sampled under cold water conditions—i.e., below 10°C (50°F)—also evidenced nitrification. No one water quality parameter by itself may be a good indicator of nitrification, but several important factors should be evaluated collectively—nitrite, nitrate, chloramine dosage and residual, ammonia, pH, heterotrophic bacterial counts, and dissolved oxygen.
Controlling nitrification in chloraminated systems
Authors: Odell Lee H. , Kirmeyer Gregory J. , Wilczak Andrzej , Jacangelo Joseph G. , Marcinko Joseph P. , Wolfe Roy L.
Published: February 2018

Data on nitrification occurrence and control in chloraminated distribution systems point to several strategies to preserve water quality during distribution and storage.

Of US water systems that chloraminate, an estimated two thirds experience some degree of nitrification in the distribution system. Measures utilities use to control nitrification were investigated through field sampling, evaluation of utility data, laboratory tests, and case studies of systems that have evaluated or attempted to control nitrification episodes. Effective control methods included instituting periodic breakpoint chlorination, reducing the available ammonia concentration, increasing chloramine residuals, cleaning the distribution system, and decreasing system detention time. Some control methods were superior for controlling a specific nitrification episode, whereas others showed more promise for reducing the long‐term potential for nitrification occurrence. According to the authors, the most important steps utilities can take to control nitrification are to thoroughly understand their systems' chloramine chemistry and to establish an effective monitoring strategy.
Toxicity of chlorine dioxide to adult zebra mussels
Authors: Matisoff Gerald , Brooks Gary , Bourland Brent I.
Published: February 2018

Effective kills depend on the right combination of concentration and exposure time.

Chlorine dioxide (ClO2) was evaluated as a control agent for adult zebra mussels using single, intermittent, and continuous exposures. A single 30‐min exposure to 20 mg/L ClO2 or higher concentration induced at least 50 percent mortality. NaOCl, KMnO4, and H2O2 were ineffective under the same conditions. Intermittent chemical exposure for 30 min each day indicated that ClO2 at concentrations of 10–20 mg/L can induce significant mortality over three to seven consecutive days (LC50 = 13.0 mg/L), but 1–5 mg/L ClO2 applied over 28 consecutive daily exposures are ineffective (<30 percent mortality). Identical intermittent exposure to NaOCl was ineffective at all tested concentrations up to 30 mg/L. Continuous exposure to ClO2 for four days was effective at concentrations >0.5 mg/L (LC50 = 0.35 mg/L), and 100 percent mortality at ClO2 concentrations >1 mg/L was achieved. NaOCl and KMnO4 were less effective. Pooled data yield median lethal dosages at which 50 percent mortality occurred of 14.5 and 82.5 mg h/L for ClO2 and NaOCl, respectively.
Improving GAC performance by optimized coagulation
Authors: Hooper Stuart M. , Summers R. Scott , Solarik Gabriele , Owen Douglas M.
Published: February 2018

Optimized coagulation results in benefits ranging from DBP reduction to improved GAC run times.

The effect of optimized coagulation on granular activated carbon (GAC) performance for removal of natural organic matter and control of disinfection by‐products was investigated. Coagulation optimized for total organic carbon (TOC) removal increased GAC run times by a factor of 2–3 over run times observed for GAC receiving conventionally treated water. The improved performance was mainly a result of reductions in influent TOC and pH after optimized coagulation, as compared with conventional pretreatment. Conventional coagulation prior to GAC was more cost‐effective than optimized coagulation, because of increased costs associated with the high alum dosages used in this study.
Evaluating plant performance with endospores
Authors: Rice Eugene W. , Fox Kim R. , Miltner Richard J. , Lytle Darren A. , Johnson Clifford H.
Published: February 2018

Monitoring for indigenous spores of aerobic spore‐forming bacteria proves a viable method of assessing treatment plant performance.

Spores of aerobic spore‐forming bacteria were used as microbial surrogates for evaluating drinking water treatment plant performance. A method for assaying for the microbial surrogate was developed. Various water sources were surveyed, and data were collected from coagulation and chlorine inactivation studies. Evaluations for spore removals and turbidity and particle removals were compared for pilot‐scale and full‐scale water treatment plants.
Assessing the risk posed by oocysts in drinking water
Authors: Haas Charles N. , Crockett Christopher S. , Rose Joan B. , Gerba Charles P. , Fazil Aamir M.
Published: February 2018

Dose–response data on human exposure to oocysts of Cryptosporidium were analyzed to determine the dose corresponding to a stated risk level.

A recent study of infection and illness in human volunteers subjected to controlled exposure to oocysts of Cryptosporidium parvum provided a suitable data base for dose–response analysis. The authors analyzed the study data, and using exponential and beta‐poisson dose–response models, arrived at an estimate of the waterborne concentrations associated with various risk levels.
Fire flow computation with network models
Authors: Boulos Paul F. , Rossman Lewis A. , Orr Chun‐Hou , Heath J. Erick , Meyer Michael S.
Published: February 2018

The authors describe a sequential search procedure that produces improved fire flow estimates at each iteration.

Water mains are usually designed to meet demands for fire‐fighting. Fire flow is the maximum flow rate available at a specified pressure, typically 20 psi (138 kPa). Water network models provide the capability to compute these flows at all points in a distribution system. This article presents a simple and rigorous sequential search procedure for computing fire flows using network models. The method can be applied manually between runs of the model, or it can easily be incorporated into existing computer codes. Examples illustrate the procedure's excellent convergence properties. Enhancement of water distribution system design, planning, and management is a principal benefit of the proposed methodology.
New York City: To filter or not to filter?
Authors: Okun Daniel A. , Craun Gunther F. , Edzwald James K. , Gilbert Jerome B. , Rose Joan B.
Published: February 2018

USEPA's expert panel concluded that both filtration and watershed protection are necessary for New York City's water supply.

Under the Surface Water Treatment Rule (SWTR), New York City is required to filter its Catskill–Delaware water supply unless it can meet the criteria to avoid filtration. A panel was appointed by the US Environmental Protection Agency (USEPA) in the summer of 1992 to advise the agency about whether to grant New York City permission to avoid filtration. The panel concluded that although the water quality criteria were met marginally, the requirements for watershed control were not met. The panel also concluded that the city would probably not be able to meet the water quality requirements of an enhanced SWTR, which would likely include, among other additional requirements, measures to control Cryptosporidium. Despite the panel's recommendation for filtration, USEPA granted New York City an avoidance of filtration first through 1993, then through 1996, 1999, and 2002. Although the city has negotiated a very useful watershed agreement with the upstate communities in the Catskill–Delaware watershed, the issues remain the same. This article assesses the issues involved.
Coliform bacteria and waterborne disease outbreaks
Authors: Craun Gunther F. , Berger Paul S. , Calderon Rebecca L.
Published: February 2018

The authors evaluate the utility of coliforms as an indicator of the vulnerability of drinking water systems to outbreaks of waterborne disease.

Coliform‐free tap water has previously been thought to be unlikely to cause waterborne disease. However, disease outbreaks (especially those caused by Giardia or Cryptosporidium) and endemic waterborne disease risks have been reported in water systems that have not violated either the 1975 or 1989 maximum contaminant level (MCL) for total coliforms. Focusing on the 1975 rule and using coliform data and investigative reports about outbreaks, the authors compared MCL violations for water systems that did and did not experience an outbreak. Coliforms were usually found in a public system during an outbreak investigation, but in the months before an outbreak, they were detected in only half of the systems and caused an MCL violation in only one fourth of them. The violation rate was not significantly different between community systems that experienced an outbreak and those that did not; usually both met the MCL. To safeguard the public against waterborne disease, microbiological monitoring must be supplemented with periodic sanitary surveys and activities that ensure adequate water quality.
Surveying arsenic occurrence
Authors: Frey Michelle M. , Edwards Marc A.
Published: February 2018

Data from US arsenic occurrence surveys are used to estimate compliance violations given a range of possible arsenic standards.

Three surveys of arsenic occurrence in US drinking water supplies were synthesized to estimate how possible arsenic standards would affect compliance. Detectable levels of arsenic (0.5 μg/L) were found in 73 percent of surface water sources and 58 percent of groundwater sources. For finished water, detectable arsenic occurred in 45 percent of surface water systems and 53 percent of groundwater systems. The authors' compliance projections for arsenic standards ranging from 2 to 20 μg/L agreed fairly well with initial estimates by the US Environmental Protection Agency. It was estimated that approximately 25 percent of all community water suppliers (11,550–11,890 systems) would violate an arsenic standard of 2 μg/L. Between 6 and 17 percent of systems (2,775–7,870) were projected to violate an arsenic standard of 5 μg/L, and 1–3 percent of systems (510–1,360) were estimated to violate an arsenic standard of 20 μg/L.
Reliability of surrogates for determining Cryptosporidium removal
Authors: Li Sylvana Y. , Goodrich James A. , Owens James H. , Willeke Gene E. , Schaefer Frank W. , Clark Robert M.
Published: February 2018

Tests show 4–6‐μm polystyrene microspheres are an accurate and precise surrogate for determining Cryptosporidium log removal in bag filters.

Testing of field‐scale bag filtration systems yielded results indicating that 4–6‐μm polystyrene microspheres can be used as a reliable surrogate for determining Cryptosporidium oocyst removal in bag filtration processes. A nearly perfect linear correlation was observed between log removals of 4–6‐μm polystyrene microspheres and Cryptosporidium parvum oocysts. The correlations between Cryptosporidium removal and other potential surrogates (including 4–6‐μm particle counts, 1–25‐μm particle counts, and turbidity) produced slopes that were substantially >1 and may vary geographically because of variations in raw water quality. The similarities and dissimilarities in log removal between Cryptosporidium oocysts and the potential surrogates for the bag filtration system resulted from their differences in size distribution.
Iron oxide–coated media for NOM sorption and particulate filtration
Authors: Chang Yujung , Li Chi‐Wang , Benjamin Mark M.
Published: February 2018

Newly developed iron oxide–coated media offers several advantages over conventional sand media for NOM removal and particulate filtration.

This study applied newly developed iron oxide–coated media (IOCM) to the removal of natural organic matter (NOM) and particulate filtration in drinking water treatment. The sorption capacity of IOCM for NOM directly depends on the amount of iron retained on the media surfaces and generally increases with the decrease of solution pH, the increase of empty bed contact time, and the concentration of Ca2+. Using olivine as the supporting medium significantly improved the performance of IOCM at neutral pH. Although the sorption capacity of IOCM is limited by the amount of oxides that can be coated on the media surfaces (about 5 percent by weight), results from the pilot studies indicated that frequent regeneration of the media (twice a week) can effectively maintain system performance at the desired level. The NOM‐laden IOCM was nearly completely regenerated using 3 bed volumes of 0.5 N sodium hydroxide solution, and NOM concentration in the regenerant was as high as 4,300 mg/L DOC. The sorption capacity of IOCM deteriorated mildly in a long‐term test, possibly because of loss of iron during the backwash cycles. Results from both bench tests and pilot studies also showed that IOCM outperformed regular sand in particulate filtration in terms of head loss buildup and turbidity breakthrough.
DBP occurrence survey
Authors: Arora Harish , LeChevallier Mark W. , Dixon Kevin L.
Published: February 2018

Evidence gathered by the American Water System suggests USEPA should revisit the proposed Stage I DBP regulations, especially TOC removal requirements and related conditions for prechlorination.

Results of a disinfection by‐product (DBP) survey and two years of distribution system DBP monitoring are presented for more than 100 treatment plants of the American Water System (AWS), the largest investor‐owned water utility in the United States. Monitoring of total organic carbon (TOC) indicated that 83 percent of the AWS surface water treatment plants that exceed a raw water TOC concentration of 2 mg/L will not receive predisinfection credit for the use of chlorine. With existing treatment practices, approximately 20 and 66 percent of the AWS water treatment plants studied will exceed the proposed Stage I and Stage II trihalomethane (THM) maximum contaminant levels (MCLs) of 80 and 40 μg/L, respectively. Similarly, approximately 16 and 52 percent of the AWS systems studied will exceed the proposed Stage I and II haloacetic acids (HAA5) MCLs of 60 and 30 μg/L, respectively. Based on these estimates, it is believed that Stage II requirements may significantly affect future water treatment practices and costs.
Predicting the formation of aldehydes and BOM
Authors: Paode Rajendra D. , Amy Gary L. , Krasner Stuart W. , Summers R. Scott , Rice Eugene W.
Published: February 2018

A study finds that aldehyde formation in ozonated water is a function of alkalinity, ozone dosage, chlorophyll a, nonhumic fraction of DOC, and DOC.

This research attempted to (1) identify water quality and water treatment parameters that can potentially influence the creation of biodegradable organic matter (BOM) and aldehydes and (2) derive correlations of BOM (estimated by measuring assimilable organic carbon [AOC] and biodegradable dissolved organic carbon [BDOC]) and aldehydes, with ozone dosage and water quality variables, through multiple regression analysis. Aldehyde formation was influenced by ozone dosage, alkalinity, nonhumic fraction of DOC, chlorophyll a, and DOC. Ozonated water BDOC level was a function of raw water BDOC concentration and ozone dosage, whereas AOC concentration in ozonated water was related to raw water AOC level, alkalinity, and ozone dosage. Multiple regression analysis showed good correlations of AOC, BDOC, and aldehydes with the variables listed.
Chloramination: its effect on distribution system water quality
Authors: Norton Cheryl D. , LeChevallier Mark W.
Published: February 2018

Coliform concentrations were reduced or eliminated in two systems after chloramination replaced use of free chlorine.

Postdisinfection using chloramines can limit coliform regrowth in pipeline biofilms and formation of disinfection by‐products (DBPs) in distribution systems. Two utilities that have had occurrences of total coliform converted from free chlorine to chloramines. Water in both distribution systems was monitored for biological and chemical quality for a year after the conversion. Coliform occurrences were eliminated in one system and reduced fourfold in the other. However, excessive concentrations of assimilable organic carbon (up to 375 μg/L) were characteristic of the latter system, as was pitting corrosion. Both factors may play a critical role in limiting coliform occurrence. Postdisinfection using chloramines rather than free chlorine has advantages including decreased coliform concentrations, decreased heterotrophic plate count and DBPs, and improved maintenance of a disinfectant residual. However, chloramination alone may not be sufficient to control coliform concentrations in all distribution systems.
Nonbiological surrogate indicators for assessing ozone disinfection
Authors: Chiou Chung‐Fan , Torres‐Lugo Madeline , Marinas Benito J. , Adams Jeffrey Q.
Published: February 2018

The authors investigate the use of fluorescent‐dyed microspheres for assessing disinfection efficiency in ozone contactors.

Fluorescent‐dyed polystyrene microspheres were used as nonbiological surrogate indicators for assessing ozone disinfection efficiency. Microspheres were exposed to various constant dissolved ozone concentrations ranging from 0.1 to 1.5 mg/L in a semibatch reactor. Experimental results showed that fluorescence decay rates were first‐order with respect to dissolved ozone concentration and independent from solution pH in the range of 6.2 to 8.5. Fluorescence intensities from individual microspheres were measured by flow cytometry. Resulting microsphere fluorescence intensity distributions at various ozonation contact times were analyzed by defining a fluorescence intensity threshold. Microspheres with fluorescence intensities above and below the threshold were considered equivalent to viable and nonviable cysts, respectively. Corresponding microsphere survivals correlated well with ozone disinfection data reported for Giardia cysts. The authors propose an experimental protocol for assessing full‐scale ozone contactor disinfection efficiency with fluorescent‐dyed microspheres.
Protozoa in river water: sources, occurrence, and treatment
Authors: States Stanley , Stadterman Kathleen , Ammon Louis , Vogel Paul , Baldizar Julie , Wright Denise , Conley Louis , Sykora Jan
Published: February 2018

A dairy farm, sewage plant, and backwash water were among sources of protozoa in the raw water treated by the Pittsburgh, Pa., water utility.

Giardia and Cryptosporidium were monitored monthly for two years to determine their occurrence in the Allegheny and Youghiogheny rivers, their source, and the efficiency of their removal by the Pittsburgh Drinking Water Treatment Plant. Sources investigated included a dairy farm stream, treated effluent from a sewage plant, and several samples from combined sewer overflows, all of which regularly contribute parasites to rivers. Raw, settled, filtered, and filter backwash waters were also sampled. Clarification and filtration generally control passage of protozoa into the drinking water, but small numbers of Cryptosporidium occasionally pass through even in the absence of treatment difficulties. Cysts and oocysts are also reintroduced into the drinking water plant via recycling of backwash water.
Assessing long‐term hydrologic effects of land use change
Authors: Bhaduri Budhendra , Grove Matt , Lowry Carmen , Harbor Jon
Published: February 2018

The curve number technique for calculating runoff is modified to estimate lost groundwater recharge.

Many communities are seeking to understand how future development may affect a watershed, and they are using this information to develop long‐term watershed management plans that protect their water supply. As part of work on the Cuppy‐McClure watershed in Indiana, a land use–runoff estimation technique was developed based on the local long‐term climate record. The technique, which uses the core of the US Department of Agriculture's curve number method, produces results that can be easily understood and used by managers, planners, and developers. The technique can estimate the effect of development on watershed hydrology, and it can quickly provide sensitivity analyses of alternative proposed land uses. Analysis of Cuppy‐McClure identified six subbasins that dominate the cumulative effects of proposed land uses and that should be the focus of watershed management.
DE filtration to remove Cryptosporidium
Authors: Ongerth Jerry E. , Hutton and P.E.
Published: February 2018

DE filtration is far more effective than conventional or direct granular media filtration in reducing concentrations of Cryptosporidium oocysts.

Laboratory‐scale testing investigated the degree of Cryptosporidium oocyst reduction provided by diatomaceous earth (DE) filtration. Three grades of DE from two manufacturers were used in the tests. Reduction was measured using seeded river water applied to Walton test filters. Tests were run for filtration rates of 1 and 2 gpm/sq ft (2.4 and 4.9 m/h). Each run was replicated three times, and quality control was rigorous. Approximately 6 logs of reduction in the concentration of Cryptosporidium oocysts can be expected under routine operating conditions using DE grades having permeability of <1.2 Darcy. Log reductions varied predictably according to the permeability of the DE grade and the filtration rate; they were significantly higher at the higher filtration rate. Agreement was excellent between runs, enabling researchers to distinguish with consistent statistical significance the differences in performance.
NOM's role in bromine and bromate formation during ozonation
Authors: Westerhoff Paul , Song Rengao , Amy Gary , Minear Roger
Published: February 2018

NOM's reactivity depends on NOM source and varies for different fractions of the same NOM.

Natural organic matter (NOM) can influence the rate and extent of bromide oxidation during ozonation and affect disinfection by‐product (DBP) formation. In batch ozonation experiments of model water samples under similar conditions, variable concentrations of bromate and organobromine formed in the presence of different NOM isolates. Differences in the source and composition of NOM, as measured by the ratio of specific ultraviolet absorbance at 254 nm to dissolved organic carbon, can account for variations in the rate of ozone and hydroxyl (HO) radical consumption by NOM. The presence of NOM significantly reduced the bromate formation relative to NOM‐free water. The mechanism for the decrease in bromate formation has two components: (1) NOM reacts directly with ozone and HO radicals to reduce the amount of oxidant available for bromide and bromine oxidation, respectively, and (2) NOM reacts with bromine, the main intermediate in the formation of DBPs.
Using aeration for corrosion control
Authors: Lytle Darren A. , Schock Michael R. , Clement Jonathan A. , Spencer Catherine M.
Published: February 2018

Under the right initial water quality conditions, aeration proves a suitable alternative for reducing lead and copper corrosion.

Aeration is a useful drinking water treatment process. Aeration has been used to remove hydrogen sulfide, methane, radon, iron, manganese, and volatile organic contaminants from drinking water. Aeration also removes carbon dioxide, which directly affects pH and dissolved inorganic carbon (DIC), the parameters that most influence lead and copper solubility. As a result, aeration can be an effective corrosion control strategy, presuming the initial pH and DIC are appropriate. Mineral precipitation brought about by water quality changes resulting from aeration may present operational constraints under some conditions. Aeration produces very consistent water quality and may be advantageous (especially to smaller utilities) because of relatively low costs and simple operational and maintenance needs.
Evaporative cooler water use in Phoenix
Authors: Karpiscak Martin M. , Babcock Thomas M. , France Glenn W. , Zauderer Jeffrey , Hopf Susan B. , Foster Kennith E.
Published: February 2018

This study takes a step toward showing how much water various evaporative cooling systems use.

The authors undertook this study to learn what fraction of total per capita water consumption in growing southwestern Sunbelt cities is made up of water used by residential evaporative coolers. In a field study, water use was metered in sample homes during two cooling seasons. Meters were placed on incoming lines that provided makeup water to the evaporative cooler reservoir. Monitoring devices were configured to capture and meter the bleedoff water so water consumption for evaporation could be separated from total water delivered to the cooler. Average annual household use of water for all homes was 108,382 gal (410,271 L). Water used by each household for cooler operation, regardless of the kind of cooler system, averaged 66 gpd (250 L/d)—15 percent of total household water use—during the 214‐day cooling season. Homes with a bleedoff system on the cooler used an average of nearly 50 percent more total water for cooler operation than did homes with no bleedoff system.
Achieving competitiveness through cultural change
Authors: Ash Leah , Rettie Melanie J.
Published: February 2018

Reengineering of a water treatment organization proves a long and difficult process but pays off in improved operations and lower cost.

Colorado Springs Utilities (CSU) has shown how a strong vision of competitiveness can help a utility overcome outdated processes and operations. In just one division, reengineered organization and work practices are saving the utility more than $2 million per year, without a loss in quality. Critical to CSU's success was upper management's steadfast vision of a new organizational culture. Changing from a traditional hierarchical management to a team environment created wins for the utility, its management, staff, and customers.
Sulfide‐induced copper corrosion
Authors: Jacobs Sara , Reiber Steve , Edwards Marc
Published: February 2018

Sulfides can accelerate the corrosion of copper pipe and elevate concentrations of copper in drinking water.

The presence of sulfides in potable water increases copper pitting and the release of copper corrosion by‐products. After 3 h of stagnation in a copper pipe, the average by‐product release of a synthetic drinking water that contained sulfides was 8.0 mg/L at pH 6.5 and 4.4 mg/L at pH 9.2. These concentrations represented a 5‐ and 50‐fold increase compared with water without sulfides. Sulfide‐induced corrosion problems might be ameliorated by removal of sulfides from the water, mechanical removal of the sulfide scale, chlorination, or deaeration. However, in the laboratory only mechanical removal of the sulfide scale and removal of sulfides from water were effective within a month. Utility case studies strongly support a relation between sulfides and increased copper corrosion problems.
Using hydraulic modeling to optimize contact time
Authors: Hannoun Imad A. , Boulos Paul F. , List E. John
Published: February 2018

Hydraulic modeling will eventually displace most field testing and bench modeling for the evaluation of clearwells.

The Safe Drinking Water Act and its amendments impose stringent guidelines on all plants that treat surface water. Virtually all such plants use clearwells to increase the duration of disinfection. A challenge in the design of these facilities is maximizing disinfection while limiting the formation of disinfection by‐products. These competing objectives can best be attained by optimizing the hydraulic performance and efficiency of clearwells.
Effect of rainfall on Giardia and crypto
Authors: Atherholt Thomas B. , LeChevallier Mark W. , Norton William D. , Rosen Jeffrey S.
Published: February 2018

Rainfall increases concentrations of Giardia and Cryptosporidium through its influence on turbidity, flow volume, and possibly other unidentified factors.

An investigation of the variability of concentrations ofGiardiacysts andCryptosporidiumoocysts in the Delaware River was conducted in 1996 at Trenton, N.J. A goal of the study was to examine the relationship between concentrations ofGiardiaandCryptosporidiumand a variety of more easily measured microbial, water quality, and meteorological parameters. A positive correlation (Spearman rank;p< 0.05) was demonstrated between concentrations ofGiardiacysts orCryptosporidiumoocysts and 15 other parameters. Increased concentrations ofGiardiaandCryptosporidiumas well as a variety of other microorganisms were associated with rainfall. The effect of rainfall on parasite concentrations is due in part to increased particulate matter in the water column following surface runoff and resuspension of river bottom and storm drain sediment.
Legionella in water distribution systems
Authors: Lin Yu‐sen E. , Vidic Radisav D. , Stout Janet E. , Yu Victor L.
Published: February 2018

Regular culturing of distribution system samples is the key to successful disinfection.

Legionnaires' disease arises from the presence of Legionella in water systems. Legionella can be found within biofilms throughout the entire water distribution system. Control measures such as copper‐silver ionization, superheat‐and‐flush procedures, ultraviolet light, instantaneous heating systems, and hyperchlorination have been applied with variable success. Specific approaches, advantages, disadvantages, and costs of each method are reviewed. Many approaches commonly recommended by public health authorities have not been scientifically validated. Results from routine environmental surveillance cultures for Legionella are the critical component for rational decision‐making.
Dynamic analysis of coagulation with alum and PACl
Authors: Matsui Yoshihiko , Yuasa Akira , Furuya Yuji , Kamei Tasuku
Published: February 2018

PACl more effectively coagulates fine particles than alum.

The coagulation kinetics of polyaluminum chloride (PACl) and alum applied to kaolin clay suspensions were compared in batch experiments. Increasing aluminum (Al) dosages reduced the time required for particles destabilization and increased the rate at which the number of primary particles decreased. PACl worked faster than alum. Photometric dispersion analysis showed that increasing Al dosages decreased the time required for floc to form. Again, this rate was faster with PACl than with alum. Increasing the Al dosage accelerated the flocculation rate because it increased collision–attachment efficiency and increased particulate volume. The rates of particle destabilization, reduction of destabilized primary particles, and agglomeration varied with mixing intensity and water temperature. Although lower temperatures slowed the particle destabilization rate, similar effects on the flocculation rate could be avoided by maintaining a constant G value. PACl was less sensitive to changes in pH, implying that PACl performed better than alum in cold water.