bluuebunny/crossref_metadata_2025 huggingface dataset:
Disinfection By‐product Formation and Control by Ozonation and Biotreatment
Authors: Miltner Richard J. , Shukairy Hiba M. , Summers R. Scott
Published: February 2018

There is increasing interest in using ozone in water treatment because it is a strong disinfectant and is able to oxidize the precursors of some disinfection by‐products (DBPs). However, ozonation itself produces DBPs, like aldehydes and ketones, and increases the concentration of bacterial nutrients by converting nonbiodegradable organic matter to more biodegradable compounds. In this study it was found that biotreatment of ozonated waters provided additional removal of precursors of total trihalomethanes, total haloacetic acids, chloropicrin, and total organic halides. Aldehydes are easily biodegradable. Piloting is recommended to determine site‐specific ozone dosages and trade‐offs in the formation of bromate and ozone DBPs and in the oxidation of chlorine DBP precursors.
Contact Filtration: Particle Size and Ripening
Authors: Clark Sarah C. , Lawler Desmond F. , Cushing Robert S.
Published: February 2018

Contact filtration (deep‐bed filtration of lake water after particle destabilization but no other treatment) was studied in laboratory‐scale experiments. Particle size distributions and pressure were measured at four different depths for several hours, the time over which filter performance generally improves, i.e., ripening occurs. Particle size distribution measurements coincided with measurements of turbidity and suspended solids but provided more detailed information. Ripening occurred for all sizes initially and continued for small sizes for several hours, but it slowed or reversed for larger particles. Increased media size (from 0.8 to 1.85 mm) allowed use of the entire bed for removal and reduced head loss, although greater depth was required for equivalent removal. Filtration velocity also affected removal efficiency, bed depth use, and head loss—but to a lesser extent than media size.
Measurement of THM and Precursor Concentrations Revisited: The Effect of Bromide Ion
Authors: Symons James M. , Krasner Stuart W. , Simms Louis A. , Sclimenti Michael
Published: February 2018

In the absence of bromide ion (Br−), method 5710B from Standard Methods is adequate for measuring trihalomethane (THM) precursor concentrations, provided a free available chlorine (FAC) residual of 3 mg/L is maintained at the end of incubation, and method 5710E from Standard Methods is appropriate for predicting THM concentrations at the consumer's tap. In the presence of Br−, method 5710B is adequate for measuring THM precursor concentrations provided only total precursor is desired. Because the initial Br−/average FAC dosage molar ratio influences bromine substitution, THM species concentrations cannot be predicted using method 5710B. Instead, method 5710E must be used. This is particularly important when evaluating THM precursor removal unit processes when the use of method 5710B may indicate greater bromine substitution in the unit process effluent than in the influet.
Formation and Control of Bromate During Ozonation of Waters Containing Bromide
Authors: Krasner Stuart W. , Glaze William H. , Weinberg Howard S. , Daniel Phillippe A. , Najm Issam N.
Published: February 2018

The results of this study show that the ozonation of waters containing bromide may produce bromate, with ozone dosage playing a critical role. The appropriate staging of ozone through two or three chambers, however, has the potential to minimize ozone residual and bromate formation while still meeting C × T criteria. The addition of hydrogen peroxide (the PEROXONE process) may increase the formation of bromate. As the pH of ozonation was lowered, the ozone dosage necessary to meet C × T criteria dropped, and less bromate was produced. The authors conclude that a better understanding of the mechanisms of bromate formation is required before it can be fully controlled.
Nitrate and Cancer: Is There a Link?
Authors: Pontius Frederick W.
Published: February 2018

A portion of the nitrate consumed in drinking water is converted to nitrite in the body. Nitrite can react in the body with secondary amines, amides, and carbamates to form N‐nitroso compounds, several of which are potential human carcinogens. Does nitrate in drinking water lead to an increased risk of cancer? Several studies summarized here have attempted to answer this question.
Trends in Water Pricing: Results of Ernst & Young's National Rate Surveys
Authors: Duke Ellen M. , Montoya Angela C.
Published: February 2018

Ernst & Young's biennial national water and wastewater rate surveys collect information on bills, rate structures, billing cycles, and special charges for utilities serving the 100 largest metropolitan statistical areas in the United States. This article presents trends and patterns observed in these surveys, which have been conducted since 1986, and provides a discussion of national and regional pricing trends supported by the survey results. The most significant trend evidenced from the surveys is a shift toward conservation rate structures, which promote more efficient use of water resources through use of uniform and inverted‐block rates, seasonal and excess‐use surcharges, and in some cases, marginal cost pricing.
The Social Acceptability of Water Conservation in Springfield, Ill.
Authors: Lant Christopher L.
Published: February 2018

Water conservation initiatives are more likely to succeed if they are socially acceptable. A survey of 2,700 residential customers of Springfield (Ill.) City Water, Light and Power was conducted to assess the acceptability of 12 possible conservation measures and the relationship between demographic and attitudinal factors and overall acceptance of conservation. Lawn watering restrictions, education, home water‐saver kits, low‐flush toilet rebates, and a low‐flow fixtures ordinance for new construction were most acceptable. Overall acceptance of conservation is strongly related to attitude regarding importance of water conservation and is also related to age, income, and type of residence.
Investigating the Effects of Chloramines on Elastomer Degradation
Authors: Reiber Steve
Published: February 2018

Evaluating elastomer degradation involved an accelerated life cycle testing protocol whereby sets of tension‐mounted coupons were exposed to specific chlorine and ammonia concentrations at elevated temperature. The coupons were inspected regularly for evidence of oxidative degradation and cracking. After a set exposure period, the coupons were assessed for tensile performance, swelling, and surface characterization. With few exceptions, solutions of chloramines produced greater elastomer swelling, deeper and denser surface cracking, more rapid loss of elasticity, and greater loss of tensile strength than equivalent concentrations of free chlorine. Elastomers most susceptible to attack were those formulated with natural or synthetic isoprenes.
Modifying ion exchange for combined removal of uranium and radium
Authors: Clifford Dennis , Zhang Zhihe
Published: February 2018

Mixing only a small amount of strong base anion resin with the strong acid cation resin in a conventional water softener results in efficient uranium removal in addition to radium removal.

Adding a small amount of strong base anion (SBA) resin to the strong acid cation (SAC) resin in a conventional water softener provides good uranium and radium removal. In tests on a well water containing 25 pCi/L radium and 120 μg/L uranium, a mixed bed containing 10 percent SBA and 90 percent SAC resin provided a product water with less than 1 pCi/L radium and 20 μg/L uranium during cyclic operation with sodium chloride regeneration. Additional tests indicated that too much anion resin or stratified resin beds caused excessive radium and uranium leakage. Also, potassium chloride was a superior regenerant to sodium chloride for elution of radium from the spent resin.
Quality degradation: implications for DBP formation
Authors: Krasner Stuart W. , Sclimenti Michael J. , Means Edward G.
Published: February 2018

The results of these studies of the Sacramento–San Joaquin River Delta demonstrate that DBP control strategies should include watershed management as well as treatment processes in other regions of the United States.

During development of the draft Disinfectants‐Disinfection Byproducts (D‐DBP) Rule, the issue of watershed management for DBP precursor control was discussed but not included in the rule. This article focuses on a major California watershed, describing examples of the types of studies that utilities can use to determine precursor sources and develop solutions for control. In addition, a chlorination and ozonation study of a five‐by‐five matrix of total organic carbon and bromide levels—which spanned a wide range of concentrations that can be expected in many US waters—provided insights into the effects of organic and inorganic precursors and disinfectants in DBP formation.
Arsenic removal by coagulation
Authors: Scott Karen N. , Green James F. , Do Hoang D. , McLean Stephen J.
Published: February 2018

This utility's goal of 90 percent arsenic removal was attained through treatment with 6.5 mg/L ferric chloride.

This study evaluated the removal of naturally occurring arsenic in a full‐scale (106‐mgd) conventional treatment plant. When the source water was treated with 3–10 mg/L of ferric chloride or 6, 10, or 20 mg/L of alum, arsenic removal was 81–96 percent (ferric chloride) and 23–71 percent (alum). Metal concentrations in the sludge produced during this study were below the state's current hazardous waste levels at all coagulant dosages. No operational difficulties were encountered.
Removing Cryptosporidium by dissolved‐air flotation
Authors: Plummer Jeanine D. , Edzwald James K. , Kelley Michael B.
Published: February 2018

DAF achieved more than a 2‐log removal of Cryptosporidium oocysts under a variety of treatment conditions.

Bench‐scale studies were used to investigate the effectiveness of dissolved‐air flotation (DAF) for the removal of Cryptosporidium parvum oocysts from a drinking water supply. Oocysts were spiked into a natural water at a concentration of 3–4 times 105 oocysts/L. Results indicate that DAF achieved a >2‐log removal of oocysts under a variety of conditions. In addition, flotation was a superior clarification process to sedimentation for the conditions tested. Coagulation and DAF conditions that minimize residual turbidity and maximize the removals of organic matter are conditions that produce high log removals of Cryptosporidium.
DBPs in chlorinated North Carolina drinking waters
Authors: Singer Philip C. , Obolensky Alexa , Greiner Anthony
Published: February 2018

Compliance with the proposed D/DBP Rule may be dictated to a much more significant degree by haloacetic acids than by THMs.

The proposed Disinfectants/Disinfection By‐products (D/DBP) Rule establishes a maximum contaminant level (MCL) for haloacetic acids (HAAs) of 60 μg/L and revises the MCL for trihalomethanes (THMs) to 80 μg/L. In anticipation of the proposed rule, researchers obtained finished drinking water from six North Carolina utilities and analyzed for THMs, HAAs, and total organic halides. Samples from representative locations within the distribution system were collected three times over 12 months to discern seasonal patterns in DBP formation. Relationships among the different by‐products were explored, as was their relationship to raw water quality. The results suggest that HAA concentrations can be as much as 50 percent greater than THM concentrations and that the occurrence of HAAs in finished drinking water may be much higher than was anticipated when the D/DBP Rule was proposed.
Biofiltration performance: part 1, relationship to biomass
Authors: Wang Jack Z. , Summers R. Scott , Miltner Richard J.
Published: February 2018

Many factors could account for the good performance of coal‐based GAC biofilters, including the quantity of biomass attached to the media.

A phospholipid analytical technique was used to measure the amount of biomass attached to the surfaces of drinking water filter media. The method was reproducible and able to detect significant differences in biomass concentrations in different filters and at various depths within filters. The amount of attached biomass decreased as filter depth increased, suggesting that most removal of natural organic matter occurred at the top of the biofilters. The results show that granular activated carbon media were able to hold more biomass than were anthracite and sand media and that concentrations of biomass in anthracite‐sand filters were lower with chlorine in the backwash water.
Assessing DBP yield: uniform formation conditions
Authors: Summers R. Scott , Hooper Stuart M. , Shukairy Hiba M. , Solarik Gabriele , Owen Douglas
Published: February 2018

Results from UFC tests will enable direct comparison of DBP formation in different water sources.

A new chlorination approach has been developed for assessing disinfection by‐product (DBP) formation under constant, yet representative conditions. The rationale used in the development of the uniform formation conditions (UFC) test and the results of a parametric sensitivity analysis are presented. Within the acceptable range of conditions, the DBP formation varied by less than 4 percent for the three waters examined. UFC test results will allow a direct comparison of DBP formation among different waters and allow the evaluation of how treatment changes affect DBP formation in a specific water.
Water quality and mixing models for tanks and reservoirs
Authors: Grayman Walter M. , Deininger Rolf A. , Green Adam , Boulos Paul F. , Bowcock Robert W. , Godwin Chris C.
Published: February 2018

Using three types of models, researchers studied mixing and water quality in an aboveground cylindrical reservoir.

Long detention times and improper mixing in tanks and reservoirs may negatively affect water quality. Mathematical and physical models of mixing and water quality dynamics may be used to determine how alternative designs or operational policies affect the quality of water within and leaving the facility. Three models—a systems model that uses a simplified representation of the reservoir emphasizing the input and output from the facility, a computational fluid dynamics model based on mathematical equations, and physical scale models of the reservoir—were applied to the Ed Heck Reservoir, a 4‐mil‐gal (0.015 X 106 m3) cylindrical reservoir in Azusa, Calif. Results of the application of each model are presented graphically along with a discussion of each model's advantages, disadvantages, and costs.
Milwaukee's crypto outbreak: investigation and recommendations
Authors: Fox Kim R. , Lytle Darren A.
Published: February 2018

Members of the USEPA team that advised Milwaukee officials during the outbreak describe their findings.

In March and April 1993, the largest US waterborne disease outbreak occurred in Milwaukee, Wis., causing illness in more than 400,000 people. The etiological agent responsible for most cases was Cryptosporidium. Milwaukee was served by two water treatment plants that used raw water from Lake Michigan. Before the outbreak, severe spring storms caused the lake's turbidity and bacterial counts to rise dramatically. During the outbreak, effluent produced by one plant had a turbidity approaching 2.5 ntu, a high reading that indicated an increase in particulates passing through the plant. The increase may have also meant an increase in passage of Cryptosporidium oocysts. This article discusses the investigation by the Water Supply and Water Resources Division (formerly the Drinking Water Research Division) of the US Environmental Protection Agency into what may have happened to allow the oocysts to pass through the treatment plant.
The cost of infrastructure needs
Authors: Hertzler Patricia Carroll , Davies Clive
Published: February 2018

A USEPA survey of drinking water infrastructure needs yields data used to construct cost models for more than 50 types of water supply projects.

A survey conducted by the US Environmental Protection Agency provided a wealth of information on the cost of drinking water infrastructure needs. This information was used to develop cost models for more than 50 types of source, treatment, storage, and transmission and distribution projects. The cost models provide the tools to accurately estimate the total infrastructure investment needed by community water systems in the United States. They also give insight into real‐world costs for common types of drinking water infrastructure projects.
Kinetics of chlorine decay
Authors: Vasconcelos John J. , Rossman Lewis A. , Grayman Walter M. , Boulos Paul F. , Clark Robert M.
Published: February 2018

Models of chlorine kinetics in distribution systems characterize chlorine decay as a combination of first‐order decay in the bulk liquid and first‐order or zero‐order decay reactions at the pipe wall.

Proper understanding, characterization, and prediction of water quality behavior in drinking water distribution systems are critical to ensure meeting regulatory requirements and customer‐oriented expectations. This article investigates the factors leading to loss of chlorine residual in water distribution systems. Kinetic rate equations describing the decay of chlorine were developed, tested, and evaluated using data collected in field‐sampling studies conducted at several water utility sites. Results indicated that chlorine decay in distribution systems can be characterized as a combination of first‐order reactions in the bulk liquid and first‐order or zero‐order mass transfer–limited reactions at the pipe wall. Wall reaction kinetic constants were inversely proportional to pipe roughness coefficients. Wide variations in both bulk reaction constants and wall reaction constants were observed among the sites.
Evaluating Ferrous Iron for Chlorite Ion Removal
Authors: Hurst Gregory H. , Knocke William R.
Published: February 2018

Fe(II) dosing proves an efficient technique for removing ClO2– over a wide range of conditions.

Effective use of chlorine dioxide as an alternative disinfectant in water treatment may require removal of the by‐product chlorite ion (ClO2–). This study evaluated the effect of alkaline conditions (pH 7–10) and the presence–absence of dissolved oxygen on the ability of ferrous iron [Fe(II)] to reduce ClO2– ion to chloride ion (Cl–). Fe(II) dosing from 3.5–4.0 mg Fe(II) per mg ClO2– provided for efficient removal of ClO2– over the targeted pH range. Furthermore, no by‐product formation of chlorate ion was observed. Results from mass balance studies indicated that approximately 95 percent of the reacting ClO2– was chemically reduced to Cl–.
Modifying a backwash trough to reduce media loss
Authors: Kawamura Susumu , Najm Issam N. , Gramith Karl
Published: February 2018

In this pilot study, simple baffles on the sidewall of backwash troughs reduced GAC loss by 70 percent.

Since the 1960s, many rapid sand filters have been modified to become high‐rate filters, and dual media have replaced sand. A common problem caused by this change is excessive loss of anthracite coal medium (5–10 percent annually) under regular filter‐washing practices. This happens because the space between the top of the filter bed and the top of the wash troughs is insufficient for the lightweight coal grains, even though it was adequate for the rapid sand filter beds. Also, rather tight spacing of wash troughs for old filter designs aggravates the loss of coal grains. The authors evaluate the loss of granular actived carbon (GAC) after existing rapid sand beds are converted to GAC beds without raising the concrete wash troughs. Results of the pilot study indicate that a simple baffle configuration can reduce media loss by as much as 70 percent.
14C‐MIB adsorption on PAC in natural water
Authors: Gillogly Thomas E.T. , Snoeyink Vernon L. , Elarde Joseph R. , Wilson Claude M. , Royal Earl P.
Published: February 2018

A new way of measuring very low concentrations of MIB allows calculation of the PAC dose needed to mitigate odors caused by MIB.

Kinetic and equilibrium studies using five powdered activated carbons (PACs) and 14C‐labeled 2‐methylisoborneol (MIB) in Lake Michigan water produced guidelines for determining the dose of PAC needed to remove MIB. The equilibrium data, supported by predictions from the equivalent background compound competitive adsorption model, indicate that the percent MIB remaining at equilibrium is a function of the carbon dosage, independent of the initial MIB concentration. Kinetic experiments, analyzed in terms of the homogeneous surface diffusion model, demonstrated that the surface diffusion coefficient, Ds, is independent of both carbon dosage and initial MIB concentration. Together these equilibrium and kinetic studies show that for any given PAC dosage in natural water and for any fixed time of contact, the percent MIB remaining in an ideal reactor is independent of the initial MIB concentration. Thus the PAC dosage required to mitigate any MIB episode for any contact time of interest may be quickly determined from a Ct/C0 × 100 percent versus Cc plot. These studies have also exhibited a new application of 14C‐MIB allowing for the rapid collection of reproducible and accurate adsorption data.
Conservation rates in the real world
Authors: Chesnutt Thomas W. , Beecher Janice A.
Published: February 2018

Conservation‐oriented rates that reflect the true price of water can change consumers' water use and pay off in reduced operating and development costs.

Old and familiar ways of setting water rates can fail to recover the cost of providing water service, can send inaccurate signals as to the worth of this scarce resource, and are becoming more and more difficult to defend. At the same time, revenues from rates and charges are essential if water agencies are to accomplish their mission of providing dependable, potable water on demand. What can water utilities do to price water more sensibly, ensure financial viability, and achieve a publicly accepted and successful rate‐making process? The California Urban Water Conservation Council has developed a technical handbook on alternative pricing approaches and their associated effects. “Designing, Evaluating, and Implementing Conservation Rate Structures”1 demonstrates how quantitative tools can be used to measure rate effects, develop strategies for managing the results of rate changes, and provide insights about the process of successful rate‐making. By linking technical knowledge with practical implementation tools, rate‐making that incorporates conservation objectives can be accomplished.
Shutdown of BAC filters: effects on water quality
Authors: Niquette Patrick , Prévost Michèle , Servais Pierre , Beaudet Jean‐François , Coallier Josée , Lafrance Pierre
Published: February 2018

Adding a filter backwash after shutdown restored the quality of filtered water to its preshutdown standard.

Biological activated carbon (BAC) filtration is used in drinking water treatment to biodegrade dissolved organic carbon (DOC) and to nitrify ammonia. This study evaluated BAC filters before, during, and after shutdown. Concentrations of five substrates were measured: ammonia, nitrite, nitrate, DOC, and dissolved oxygen. Media samples were taken simultaneously at similar depths to evaluate the effect of a shutdown on the densities of fixed bacteria. Dissolved oxygen concentrations quickly dropped below 2 mg/L within the BAC filters during the first 2 h of filter shutdown. At the same time, nitrite and bromide concentrations increased rapidly. Fixed bacterial biomass densities, measured at several depths in the filter after a 24‐h shutdown, declined. Concentrations of DOC and ammonia, measured in the effluent after the filter was restarted, were higher than those measured before shutdown. Backwashing after shutdown, before the filter was returned to normal operation, eliminated these negative effects and restored the biodegradation performance of the BAC filters.
DBP formation potential of aquatic humic substances
Authors: Pomes Michael L. , Green W. Reed , Thurman E. Michael , Orem William H.
Published: February 2018

Terrestrial vegetation commonly shed into reservoirs contains chemical precursors of DBPs.

Aquatic humic substances (AHSs) in water generate potentially harmful disinfection by‐products (DBPs) such as haloacetic acids (HAAs) and trihalomethanes (THMs) during chlorination. AHSs from two Arkansas reservoirs were characterized to define source, identify meta‐dihydroxybenzene (m‐DHB) structures as probable DBP precursors, and evaluate predicted HAA and THM formation potentials. Elemental nitrogen content < 1 percent, phenol content > 0.5 μeq/mg, δ13C values of –27%o, and low yields of syringyl phenols found by cupric oxide (CuO) oxidation suggest a pine tree source for the AHSs found in the Maumelle and Winona reservoirs in Little Rock, Ark. CuO oxidation yielded fewer m‐DHB structures in Maumelle AHSs than in Winona AHSs. A higher 3,5‐dihydroxybenzoic acid (3,5‐DHBA) content correlated with increased HAA and THM formation potential. The 3,5‐DHBA concentration in Winona AHSs was similar to the range found in AHSs extracted from deciduous leaf litter, twigs, and grass leachates.
Desktop guidance for mitigating Pb and Cu corrosion by‐products
Authors: Edwards Marc , Jacobs Sara , Dodrill Donna
Published: February 2018

Desktop studies accurately predict trends in corrosion by‐product release.

Utility experiences were examined to assess the reliability of solubility models and decision trees in forecasting control of lead (Pb) and copper (Cu) corrosion by‐products. Such approaches cannot quantitatively predict effectiveness of corrosion control. For example, even the best‐fit solubility models explain only about 35 and 18 percent of the quantitative variation in 90th percentile Cu and Pb release, respectively. However, the decision trees and solubility models are qualitatively consistent with utility experience and are thus useful when promising water quality changes are identified to mitigate corrosion by‐product release. Utility experiences confirm that an optimal alkalinity range (20–40 mg/L as CaCO3) exists for Pb corrosion control above pH 8.5, a higher mass ratio of chloride to sulfate tends to worsen Pb by‐product release, and detectable color can signal a natural organic material content that may adversely affect compliance with the Cu action limit.
Model calibration data: the good, the bad, and the useless
Authors: Walski Thomas M.
Published: February 2018

Comparisons between field data and model results need to be made with “good” field data.

Water distribution models are used to simulate a variety of conditions, including extreme flow events such as maximum hour demands and fire flows. Some models are tested only under average demand conditions, in which head loss is commonly of the same order of magnitude as errors in head loss measurements. Data collected when head loss is small in comparison with errors may give the false impression that the model is properly calibrated. Substantial errors may exist in the model that will not become apparent until the model is used at a time when head loss and velocity are high. This article contains guidelines for collecting data so that the model calibration will be meaningful.
Applying DBP models to full‐scale plants
Authors: Westerhoff Paul , Debroux Jean , Amy Gary L. , Gatel Dominique , Mary Veronique , Cavard Jacques
Published: February 2018

A case study suggests that the use of site‐specific reactivity coefficients and chlorine consumption results in more accurate models of trihalomethane formation.

Because of increasing concern about balancing health risks for microbiological control and disinfection by‐product formation, utilities are closely examining and optimizing disinfection practices. The authors present a methodology for developing site‐specific, inplant (finished water) chlorine (Cl2) residual and trihalomethane (THM) formation models. In a case study, the methodology was applied at three operating water treatment plants in the Paris suburbs. A key obstacle was the limited historical record of bromide (Br–) occurrence. However, lab chlorination experiments indicated that approximately 10 percent of Br– was typically incorporated into THMs. In‐plant Cl2 residuals were accurately simulated with a simple first‐order Cl2 consumption model. The most accurate THM simulations were obtained using a recently developed US Environmental Protection Agency model that incorporates species‐specific reactivity parameters.
Assessing biodegradable organic matter
Authors: Volk Christian J. , LeChevallier Mark W.
Published: February 2018

High temperature, high BOM concentration, and low disinfectant residual promote regrowth of coliforms in distribution systems.

This article summarizes data collected during various surveys that assessed four aspects of biodegradable organic matter (BOM) in drinking water: (1) BOM concentrations entering distribution systems, (2) the relationship between concentrations of assimilable organic carbon (AOC) and biodegradable dissolved organic carbon (BDOC), (3) field tests of a simple method of measuring BDOC using bioreactors, and (4) the effect of BOM on coliform occurrences in distribution networks. Overall, average concentrations of AOC and BDOC in plant effluent were 100 μg/L and 0.32 mg/L, respectively. A statistically significant but weak relationship between AOC and BDOC concentrations suggests that both parameters need to be monitored during biostability studies because they provide different pieces of information. BDOC bioreactors are useful for measuring BDOC concentrations at water utilities. However, they require a long time to colonize and must adapt to water at the site where they are used. Coliform occurrences were associated with three factors: temperature, disinfectant type and concentration, and AOC concentration. When threshold values for these factors were exceeded (15oC, AOC > 100 μg/L, and dead‐end disinfectant residuals < 0.5 mg/L for free chlorine or 1.0 mg/L for chloramines), the probability of coliform occurrences greatly increased.
Monochloramine and Legionnaires' disease
Authors: Kool Jacob L. , Carpenter Joseph C. , Fields Barry S.
Published: February 2018

Use of monochloramine as a residual disinfectant could prevent Legionnaires' disease in communities throughout the United States.

Legionnaires' disease is caused by Legionella bacteria, which live in biofilm in natural and synthetic aquatic environments. The most frequent route of infection is inhalation of contaminated aerosol, which is often produced by faucets, showers, or cooling towers. Although the disease can be disseminated in potable water, the effects of the disinfection methods used by municipal water treatment facilities on the occurrence of Legionnaires' disease have not been studied. This article describes an epidemiological study in which methods for disinfecting potable water supplied to 32 hospitals where outbreaks of Legionnaires' disease have occurred are compared with methods for water supplied to 48 randomly selected control hospitals. Hospitals supplied with drinking water containing free chlorine were 10.2 times more likely to have reported an outbreak of Legionnaires' disease associated with potable water than hospitals that used water with monochloramine as a residual disinfectant (odds ratio—10.2; 95 percent confidence interval—1.4–460).
Cryptosporidium during a simulated outbreak
Authors: Gale Paul , Stanfield Geoff
Published: February 2018

Monitoring programs often underestimate the total oocyst loading and, thus, the risk of infection.

Counts of Cryptosporidium oocysts in 100‐L volume “spot” samples of treated water have been simulated for conditions representative of an outbreak. The counts agree well with those reported in outbreaks in the United Kingdom and the United States. Whereas 33 percent of 100‐L samples contained no oocysts, a small proportion contained hundreds and even thousands of oocysts. The risk of Cryptosporidium infection is directly related to the total number of oocysts entering the distribution system in the treated water as represented by the arithmetic mean oocyst density. Monitoring programs based on taking single spot 100‐L volume samples will tend to miss the “all important” high‐count samples and thus underestimate the arithmetic mean and the risk to public health. Spot samples recording 0 oocysts/100 L therefore provide very little reassurance. To detect temporal variation in the form of infrequent high‐count spikes, the Cryptosporidium regulations in the United Kingdom require continuous monitoring of treated water as it leaves the treatment facility.
Preozonation effects on coagulation
Authors: Schneider Orren D. , Tobiason John E.
Published: February 2018

Depending on the type of coagulant used, preozonation can help or hinder the removal of organic matter.

The effects of preozonation on interactions among coagulants, particles, and natural organic matter were examined at bench scale through a series of jar tests using different organic matter, pH values, and coagulants. When alum was used as a coagulant, preozonation hindered turbidity and dissolved organic matter (DOM) removal at the conditions tested. When cationic polymers were used as the coagulant, however, preozonation led to small but statistically significant increases in the removal of both turbidity and DOM. When polyaluminum chloride was used as the coagulant for several natural waters, preozonation aided turbidity and DOM removal in one instance and hindered removal of particles and organic materials in another instance. The authors hypothesize that preozonation reduces the surface charge of particulates, leading to better coagulation by charge neutralization.
Titration of Chlorine: Amperometric versus Potentiometric
Authors: Hernlem Bradley J. , Tsai Lee‐Shin
Published: February 2018

The ability to accurately measure chlorine or other disinfectants in water is important for control of microorganisms. Whereas amperometry is specified for chlorine in Standard Methods for the Examination of Water and Wastewater, manufacturers of automatic titrators are marketing their potentiometric devices for such titrations. In this article, the electrochemical basis for amperometric and potentiometric endpoint detection is examined, and two amperometric and two potentiometric methods are compared. Both amperometric methods are shown to be superior to potentiometric endpoint detection and amenable to automatic titration. Finally, fundamentals of amperometry are discussed, and the simple circuit that was used to perform amperometric titrations using a modified automated pH/potentiometric titrator is presented.
NDMA Formation in Water and Wastewater
Authors: Najm Issam , Trussell R. Rhodes
Published: February 2018

N‐nitrosodimethylamine (NDMA) is a carcinogen known to be present in various foods and industrial products. The US Environmental Protection Agency has established a 10–6 cancer risk level for NDMA of 0.7 ng/L. NDMA has been found in the effluents of various water and wastewater plants, but its formation mechanism is not yet understood. This study evaluated NDMA formation during various water and wastewater treatment processes including chlorination and chloramination, ozonation, and ion exchange. On the basis of the limited results obtained in this study, NDMA appears to be a by‐product of the chloramination of water and wastewater, with the level of NDMA formed directly related to the chloramine dose. In the waters tested, NDMA did not form on contact with free chlorine or ozone. Contact of one water with typical levels of amine‐based polymer did not form any measurable NDMA levels (<2 ng/L). Batch testing was conducted with four strong‐base anion exchange resins contacted with untreated groundwater and with buffered deionized water. Results showed that some resins might leach or form NDMA and the level of NDMA produced is a function of the chemical functional group on the surface of the resin.
Aging of copper pipes by drinking water
Authors: Lagos Gustavo E. , Cuadrado Claudia A. , Letelier M. Victoria
Published: February 2018

Thermodynamic models were used to correlate experimental and field data for the concentrations of copper (Cu), anions, and cations in drinking water with Cu‐containing scales on the inner walls of pipes. This study focused special attention on the aging processes of these scales. Precipitation and dissolution were predicted to be the main aging causes for Cu scales present on the inner walls of pipes. When data were grouped by the solid that controls solubility, the average 8‐h stagnant Cu concentration in drinking water was found to decrease linearly with average pipe age. For these average values, langite was the most soluble and youngest film, followed in both solubility and age by cupric hydroxide, azurite, brochantite, malachite, and tenorite. The more stable solids—malachite and tenorite—were 8 and 16 times less soluble, respectively, than the most soluble solid, langite. Scales usually contained more than one compound, a finding that was attributed to temperature changes, variability of water composition, long stagnation periods, and aging. During the aging process, parts of a young scale surface area may be covered and blocked for further reaction by a precipitate. During long stagnation periods, such factors as changes in pH, oxygen, and carbon dioxide concentrations and precipitation of calcium solids may induce a different Cu compound precipitate.
DOC and DBP precursors in western US watersheds and reservoirs
Authors: Nguyen My‐Linh , Baker Lawrence A. , Westerhoff Paul
Published: February 2018

The Horseshoe‐Bartlett water supply reservoir system on the Verde River in Arizona was studied to determine the impact of hydrologic variability on dissolved organic carbon (DOC) export from the watershed and DOC production within the reservoir system. High DOC concentrations occurred during spring snowmelt and late summer monsoon rains. The majority (∼90%) of DOC loading (kilograms per month) from the Verde River watershed occurred in the spring. Bacterial consumption and algal production of DOC changed the chemical characteristics of DOC in the reservoir. DOC loading was reduced by 21 to 38%, and haloacetic acid precursor loading was reduced by 30 to 45% as water passed through the Horseshoe‐Bartlett reservoir system in 1998–99. Depending on annual hydrologic patterns and reservoir operation, the Horseshoe‐Bartlett reservoir system can either produce or consume DOC.
Chlorite and Chlorate ion variability IN DISTRIBUTION SYSTEMS
Authors: Baribeau Hélène , Prévost Michèle , Desjardins Raymond , Lafrance Pierre , Gates Donald J.
Published: February 2018

This study tracked changes in chlorite ion (ClO2–) and chlorate ion (ClO3–) concentrations in the distribution system of the City of Laval, Québec, following use of chlorine dioxide (ClO2) or free chlorine. Water was collected in small‐ and large‐diameter pipes with respect to the residence time of each sampling point. In the network fed by a treatment plant using ClO2 in postdisinfection, ClO2– concentrations decreased with increasing water residence time. In the networks fed by treatment plants using free chlorine in postdisinfection, ClO2– levels remained below the method detection limit (MDL). ClO3– concentrations measured in the network following ClO2 postdisinfection were found to be either below the MDL or stable at a low level (0.09 mg/L) in cold water; ClO3– levels decreased slightly in warm water with increasing residence time. In the networks using free chlorine as a postdisinfectant, ClO3– levels showed significant variations in their overall concentrations during different samplings or with specific changes in their concentration related to residence time.
Effect of soluble Mn concentration on oxidation kinetics
Authors: Gregory Dean , Carlson Kenneth
Published: February 2018

This study examined the effect of initial manganous ion (Mn2+) concentration and oxidant dose on the oxidation of Mn2+ to Mn oxide during water treatment. The oxidants studied were chlorine dioxide (ClO2), potassium permanganate (KMnO4), and ozone. Initial Mn2+ concentrations were 60, 200, and 1,000 μg/L, and the goal of the treatment was a final Mn2+ <10 μg/L. Bench‐scale experiments were performed by applying different doses of each oxidant to a raw surface water and measuring Mn2+ residuals over time. For all experiments, the ambient raw water conditions were pH 7.0, 9°C, and total organic carbon = 3.4 mg/L. Oxidation kinetics for low initial Mn2+ concentrations (60 and 200 μg/L) were significantly slower than for high concentrations (1,000 μg/L). For the lower initial Mn2+ levels, ClO2 was the only oxidant that consistently produced final Mn2+ <10 μg/L, generally within 60–120 s. All oxidants produced final Mn2+ <10 μg/L when the initial Mn2+ concentration was 1,000 μg/L. Oxidation with ozone consistently resulted in soluble Mn2+ >20 μg/L after 5 min, with the formation of permanganate ion in many cases. For low Mn2+ concentrations, 90% oxidation by KMnO4 required 15–30 min.
Expanded Summary: Modeling intentional distribution system Contamination and Detection
Authors: Allmann Ytimothy P. , Carlson Kenneth H.
Published: February 2018

The objective of this study was to utilize commercial distribution system modeling software to understand how a drinking water system could be affected by the intentional introduction of chemical contaminants. The hydraulic model results are used to estimate the risk involved in several feed scenarios and chemical contaminants. The model results are then combined with concentration‐response sensitivity data from routine monitoring instruments to determine the ability of each chemical contaminant to be detected. Because the four chemicals studied ‐‐ parathion, VX, sodium monofluoroacetate (1080) and cyanide ‐‐ are modeled as highly persistent, their comparative effects are determined by the toxicity of the highest practical dosage. The results of the modeling scenarios show that large‐scale contamination of a drinking water system may be accomplished through backflow into major network water supply lines. Strategically located points of attack outside of the major supply lines can also produce large‐scale contamination at lesser concentrations. Points chosen at random for a covert contamination attack within the distribution system will optimally affect an area of a few neighboring streets of up to 1 square mile, depending on the pipe velocities and flow patterns within the distribution system as well as other factors.
Piloting proactive, advanced leakage management technologies
Authors: Kunkel George , Sturm Reinhard
Published: February 2018

Even those utilities that practice ongoing leak detection and repair are often thwarted by the return of leakage levels soon after repair work is complete. The “find‐and‐fix” nature of a traditional leak detection and repair program does not address the cause of most leakage. The Philadelphia (Pa.) Water Department undertook a pilot project to assess leakage occurrences holistically and implement new approaches, such as advanced pressure management, to shift to a “predict‐and‐ prevent” mode of operation. This article describes an effective approach to infrastructure management that has potential for water utilities to control unnecessary leakages, reduce water withdrawals from water resources, and better sustain existing infrastructure at a fraction of the typical cost for infrastructure replacement.
Postdisaster Water Supply: The Local—State—Federal Nexus and Recommendations for Speeding the Response
Authors: Daniel Phillippe A. , Morley Kevin M.
Published: February 2018

This article discusses a report recently released by the U.S. Environmental Protection Agency (USEPA) called, “Planning for an Emergency Drinking Water Supply” (USEPA, 2011). This resource not only addresses practical considerations for local planning but also discusses the roles and responsibilities among various levels of government regarding emergency water supplies. The report covers technical planning elements and presents key findings that can improve postdisaster responsiveness in relation to emergency water supplies. The principal findings outlined in the report are the basis for this article.
Off‐the‐shelf accuracies of residential water meters
Authors: Neilsen Martilyn A. , Barfuss Steven L. , Johnson Michael C.
Published: February 2018

The accurate measurement of potable water by metering is a viable approach to conserving water resources and encouraging responsible water use. When utilities meter water and water consumers become accountable for their water use, consumers typically become more efficient with their water use. For this reason, water metering has become an important tool in water conservation and in billing consumers fairly. However, many of the residential water meters being used in the United States do not meet AWWA accuracy standards. This study provides a common reference for accuracy by investigating all 5/8 times 3/4‐, 3/4‐, 1‐, 1 1/2‐, and 2‐in. meters available in the United States by comparing them with the corresponding AWWA standard for cold‐water meters. Although specific manufacturers are not named, this research shows the need for greater quality control by manufacturers and a great stewardship by utilities to ensure that the meters they are installing meet AWWA standards.
Balancing financial sufficiency and community sustainability
Authors: Raftelis George A.
Published: February 2018

In today's weak economy utilities are struggling to generate adequate revenues while attempting to respond to their communities' passion to be more “green,” conservation‐ focused, and responsive to other programs that enhance community sustainability. A major part of the solution to this dilemma is for utilities to recognize the challenge, develop an effective solution, and gain community/stakeholder acceptance of the solution. The challenge is for utilities to find innovative ways to generate revenues, lower operational costs, and embrace effective sustainability initiatives. Some leading‐edge utilities have gone outside their missions to meet these challenges, selling products and services to increase the revenue stream feeding their organizations. Toledo, Ohio's water utility produces and markets bottled water. Two utilities in South Carolina have found ways to expand their existing business: the Grand Strand Water and Sewer Authority in Myrtle Beach provides plumbing services to homes and businesses and the Spartanburg Water System produces and sells ice in its community. Some utilities with large land holdings pump up their bottom line by selling timber. Many utilities are implementing or supporting programs to protect and preserve the environment; others are learning the value of gaining stakeholder acceptance of both creative revenue‐generation approaches and community sustainability programs. They've come a long way from the engineering and operations‐ focused organizations of the past.
Optimal range of injection rates for a lymphatic drug delivery system
Authors: Fujii Honoka , Horie Sachiko , Takeda Kazu , Mori Shiro , Kodama Tetsuya
Published: February 2018

The lymphatic drug delivery system (LDDS) is a new technique that permits the injection of drugs into a sentinel lymph node (SLN) at an early stage of tumor metastasis, thereby treating metastasis in the SLN and its secondary lymph nodes (LNs). The quantity of drug required for a LDDS is much smaller than that needed for systemic chemotherapy. However, the relationship between the rate of drug injection into a SLN and the amount of drug reaching the secondary LNs has not been investigated. In this study, we used an MXH10/Mo‐lpr/lpr mouse model to show that the optimal rate for the injection of a fluorescent dye by a LDDS was 10 to 80 μL/min. An injection rate of 10 to 80 μL/min was able to fill the downstream LN. However, an injection rate of 100 μL/min drove the fluorescent dye into the efferent lymphatic vessels and thoracoepigastric vein, decreasing the amount of dye retained in the downstream LN. Bolus injection (defined as an injection rate of 2400 μL/min) was unable to deliver fluorescent dye into the downstream LN. These results agree with the impulse values calculated from the injection pressures in the upstream LN. We anticipate that our findings will facilitate the development of a LDDS for use in the clinic.