bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating costs for integrated membrane systems
Authors: Chellam Shankararaman , Serra Christophe A. , Wiesner Mark R.
Published: February 2018

Despite greater NF fouling rates, life cycle costs for membrane facilities appear to be reduced when membranes are operated at higher permeate fluxes and feedwater recoveries.

Nanofiltration (NF) costs attributable to variations in chemical cleaning intervals (resulting from changes in permeate flux and feedwater recovery) were estimated based on membrane fouling rates, associated cleaning intervals, backwashing frequencies, permeate fluxes, and feedwater recoveries observed at pilot scale. Costs of integrated membrane systems using microfiltration (MF), ultrafiltration (UF), and conventional treatment to treat surface water prior to NF were compared. Costs of large systems (>3.8 ˇ 104 m3/d [10 mgd]) were also estimated and compared with extrapolations from cost surveys of existing membrane installations. Results suggest that the higher NF fouling rates observed following conventional treatment compared with MF and UF pretreatment may not translate into higher costs. Despite significant increases in fouling rates, membrane treatment costs decreased with increasing permeate flux and increasing feedwater recovery.
Detachment of particles during biofilter backwashing
Authors: Ahmad R. , Amirtharajah A.
Published: February 2018

A model explains why bacteria and organic polymers are more difficult to remove than nonbiological particles during biofilter backwashing.

Granular activated carbon (GAC) biological filters accumulate both biological and nonbiological particles on the filter bed. The difference in the way these groups of particles detach during backwashing is an important consideration in biofilter operation. This study compared the detachment of biological and nonbiological particles during filter backwashing and analyzed experimental results in terms of a microscopic force model. Filtration and backwashing experiments were completed in a glass column packed with GAC–sand media and an indigenous bacterial population. Compared with hydrophilic colloids, hydrophobic colloids produced a deeper primary minimum in interactions between particles. Consequently, hydrophobic bacteria were more strongly attached to the GAC surface than were hydrophilic clay particles. During backwashing of the biological filter, maximum turbidity occurred close to zero time, whereas maximum bacterial detachment occurred later.
The case for maintaining a disinfectant residual
Authors: LeChevallier Mark W.
Published: February 2018

North American water suppliers should continue to maintain a disinfectant residual until limitation of bacterial regrowth and control of distribution system contamination are better understood.

Maintenance of a disinfectant residual in drinking water systems has been the cornerstone of sanitary engineering for nearly a century. The author argues that eliminating the disinfectant residual in North American systems is ill advised until issues related to controlling bacterial regrowth and distribution system contamination are better understood. In the meantime, the water supply industry should direct its efforts toward making disinfection practices compatible with other water quality and aesthetic goals.
Booster chlorination for managing disinfectant residuals
Authors: Tryby Michael E. , Boccelli Dominic L. , Koechling Margarete T. , Uber James G. , Summers R. Scott , Rossman Lewis A.
Published: February 2018

Booster chlorination allows disinfection in the treatment plant and maintenance of a residual in the distribution system to be viewed as separate treatment objectives.

Booster chlorination is an approach to residual maintenance in which chlorine is applied at strategic locations within the distribution system. Situations in which booster chlorination may be most effective for maintaining a residual are explained informally in the context of a conceptual distribution system. To form the basis of a quantitative analysis of booster chlorination, experiments simulated chlorine decay under booster conditions. These experiments suggested a conceptual model for bulk chlorine decay, which is used to analyze an example representing a header pipe serving two distinct zones in a distribution system. The chlorine mass savings associated with booster chlorination in this example are derived and used to show the influence of flow rates, residence times, and decay kinetics on the effectiveness of booster chlorination. The role of booster chlorination is also discussed as part of coordinated treatment efforts meant to manage the risks associated with biological regrowth and disinfection by‐products.
Complying with future water regulations
Authors: Pontius Frederick W.
Published: February 2018

With regulatory activity picking up momentum into 2000, utilities must anticipate and strategically plan for compliance.

To comply with future regulations, water utilities will need to anticipate and strategically plan for upcoming regulatory requirements. Existing regulations set by the US Environmental Protection Agency under the Safe Drinking Water Act have been previously reviewed. This article reviews current regulatory trends that water utilities should consider in strategic planning so that they can comply with new rules within the required time frames.
Isotopic uranium activity ratios in California groundwater
Authors: Wong Carolyn T. , Okamoto Howard S. , Milea Alexis M. , Perera S. Kusum , Baumann Frank J.
Published: February 2018

Whether the uranium MCL is met in California depends on what conversion factor is used.

Uranium, a kidney toxicant and a radioactive material, is present at elevated concentrations in groundwater in some states. In 1991 the US Environmental Protection Agency proposed a maximum contaminant level (MCL) for uranium in drinking water of 20 μg/L or 30 pCi/L (1.1 Bq/L). In 1992 California adopted an MCL of 20 pCi/L (0.74 Bq/L). Because California regulations permit analysis of uranium by either mass or radiochemical techniques, a reliable factor that converts values from mass to activity is required to determine compliance with the California MCL and any future federal MCL. The conversion factor for groundwater may differ markedly from that of the natural crustal abundance of uranium. This study compared values determined by three mass measurement techniques and two radiochemical techniques. It is suggested that a conversion factor of 0.79 pCi/μg be used to determine compliance with the California MCL.
Bacterial levels of new mains
Authors: Haas Charles N. , Gupta Mukul , Burlingame Gary A. , Chitluru Raveendra B. , Pipes Wesley O.
Published: February 2018

Research into disinfection requirements of new water mains indicates that the level of microbial loading is closely related to pipe surface area.

Protecting the quality of water delivered to consumers requires protecting the distribution system. An important facet of this protection is disinfection of new mains. This work sought to assess the level of microbial loading (measured by heterotrophic plate count) on new mains. The results, combined with information on sensitivity of the indigenous organisms to disinfectants, may assist in the development of appropriate guidelines for disinfecting new mains.
Inspecting systems for leaks, pits, and corrosion
Authors: Makar Jon , Chagnon Nathalie
Published: February 2018

Old and new leak detection techniques were evaluated regarding their effectiveness in preventing water loss from metallic and prestressed concrete pipe.

The National Research Council Canada (NRC) recently completed a project to assist the city of Montreal, Que., in determining the condition of its water and sewer system. NRC staff members reviewed available and future diagnostic techniques for both systems; conducted experiments on corrosion monitoring, closed circuit television inspection, and mechanical inspection methods; and provided general scientific advice during the course of the project. This article describes the results of the review of diagnostic techniques for metallic and prestressed concrete pipes. Both older techniques such as water audits and leak detection and new approaches such as acoustic emission monitoring and remote‐field‐effect inspection are discussed. Advantages and disadvantages of each technique are tabulated, and approaches are suggested for combining the techniques to diagnose a water system completely.
Unidirectional flushing: a powerful tool
Authors: Antoun Edward N. , Dyksen John E. , Hiltebrand David J.
Published: February 2018

Unidirectional flushing can help ensure that water is delivered to the consumer's tap with minimum degradation in quality.

Distribution system deficiencies continue to be responsible for more than 25 percent of waterborne disease outbreaks in the United States each year, a statistic that underscores the need for water suppliers to effectively control water quality within the distribution system. Flushing is one of the most powerful tools available to a water utility for maintaining this control. Unidirectional flushing (UDF) is a refinement designed to bring water through the system in a controlled fashion at velocities sufficient to provide a scouring action within the distribution piping. First developed in the early 1990s, UDF is being utilized by a growing number of utilities as a cost‐effective way of improving and preserving water quality in the distribution system. In this overview of UDF, the authors summarize the technique's key components and potential benefits and explore how UDF fits into overall efforts to control distribution system water quality.
Wet‐pipe fire sprinklers and water quality
Authors: Duranceau Steven J. , Poole Jack , Foster Jacquline V.
Published: February 2018

Cross‐connection control in new wet‐pipe fire sprinkler systems should be vigorously pursued, but retrofitting is not recommended.

This article describes the results of an 18‐month collaborative investigation with 30 water purveyors that studied the effects of Class 1 and Class 2 wet‐pipe fire sprinkler systems on drinking water in distribution mains. In water samples taken from a variety of commercial wet‐pipe fire sprinkler systems, water quality exceeded the primary standard for lead and cadmium and the secondary standards for iron, manganese, sulfate, color, odor, and total dissolved solids. In field‐scale backflow simulations of an average 3‐min hydrant‐flow test, about 100 gal (0.4 m3) of water backflowed from a wet‐pipe fire sprinkler system when the check valve was caused to fail in the open position. The estimated relative risk of being seriously injured in nonresidential fires is 33 times as great as the increased risk of contracting a waterborne illness after backflow has occurred. Retrofitting existing Class 1 and Class 2 wet‐pipe fire sprinkler systems that do not currently have backflow prevention assemblies would cost about $4.4–6.0 billion nationwide and was deemed not cost‐effective.
USEPA method 1622
Authors: Clancy Jennifer L. , Bukhari Zia , McCuin Randi M. , Matheson Zoë , Fricker Colin R.
Published: February 2018

This method for analyzing Cryptosporidium in water has proved to be a significant improvement over the Information Collection Rule method.

Problems with the Information Collection Rule (ICR) method for determining concentrations of Cryptosporidium oocysts and Giardia cysts in water are well documented. They include low and highly variable recoveries, high false‐positive and ‐negative rates, and poor precision and accuracy. The method is also technically difficult. To develop regulations, the US Environmental Protection Agency (USEPA) needs accurate information on the occurrence of protozoa in US source water. The inability to gather this information during the ICR led to development of an alternative method for analysis of Cryptosporidium. Method 1622 was developed and validated for use in the supplemental surveys, which USEPA hopes will provide reliable data on Cryptosporidium occurrence in US source water. Method 1622 is a significant improvement over the ICR method. In this two‐laboratory validation, the overall recovery of method 1622 is about 35 percent with a 100‐oocyst spike dosage. No nondetects were reported in the 32 natural samples analyzed, and the entire 10‐L sample was analyzed on a single well slide. Elimination of subsample analysis in method 1622 reduces the possibility of uneven oocyst recovery that can lead to over‐ or underestimation of total numbers in a sample. USEPA's 13‐laboratory round‐robin collaborative trial of method 1622 showed that it is robust, with an overall recovery of 43 percent.
Using chlorite ion to control nitrification
Authors: McGuire Michael J. , Lieu Nancy I. , Pearthree Marie S.
Published: February 2018

Laboratory and field studies of five Texas distribution systems suggest that chlorite ion has significant potential for controlling nitrification in chloraminated water.

Controlling nitrification is essential if chloramines are to be a viable alternative disinfectant scheme for distribution systems in all types of environments. This article reviews problems associated with nitrification and presents laboratory and field evidence for using the chlorite ion (ClO2–) to control nitrification in distribution systems. Laboratory experiments in this study showed that even low dosages of ClO2– (0.05 mg/L) can inactivate 3–4 logs of ammonia‐oxidizing bacteria (AOB) over several hours. Higher concentrations of ClO2– inactivate all of the AOB in as little as 30 minutes. Field investigations at five Texas water utilities showed that the presence of ClO2– in the distribution systems resulted in less loss of chloramines and ammonia–nitrogen and thus less nitrification than in those systems in which ClO2– was not present. The ease of use of ClO2– is compared with other, more traditional nitrification control measures.
Factors affecting filtered water turbidity
Authors: Lusardi Peter J. , Consonery Phil J.
Published: February 2018

A study of 75 filtration plants found that operator awareness and commitment to excellence may be more important to performance than key water quality, design, and operational variables.

Approximately 8 million of Pennsylvania's 12 million residents receive water from 329 surface water treatment plants. This study evaluated the performance of a subset of these plants to determine whether they are prepared to meet the turbidity treatment technique requirements of the Enhanced Surface Water Treatment Rule. Using 75 filtration plants, the authors reviewed key water quality, design, and operational variables to determine their effect on filtered water turbidity. Except for plants that did not use a coagulant, served populations of < 3,300 people, or used streams for source water, there was no strong statistical correlation between any of the variables and filtered water turbidity. Many plants were able to consistently achieve low turbidity levels despite limitations such as small system size, plant age, or high source water turbidity. The results of this study show that intangible variables such as commitment to achieving low turbidity, operator skill level, and operator attention appear to be more important than tangible variables such as source water quality, ownership type, plant age, coagulant type, and other operational or design factors.
Design and operation of high‐rate filters
Authors: Kawamura Susumu
Published: February 2018

Practical observations improve the design and operation of filtration systems.

Filtration is the fundamental system in a water treatment process train that removes suspended solids, including microorganisms such as Cryptosporidium oocysts, Giardia cysts, and parasite eggs. To constrain costs, the design of any filter should be simple, reliable, proven, easy to build, and easy to operate; and it should require the minimum capital, operation, and maintenance costs while providing maximum operational flexibility. A robust filter design should be based on knowledge, experience, and user feedback. This article provides practical guidance on the design of high‐rate filtration systems.
Alternative tests for evaluating NF fouling
Authors: DiGiano Francis A. , Arweiler Sabine , Riddick J. Arthur
Published: February 2018

Two alternative batch tests use a smaller sample and simpler experimental setup.

The batch recycle membrane test (BaReMT) and batch internal recycle membrane test (BaIReMT) were developed as simpler alternatives to the rapid bench‐scale membrane test (RBSMT) currently recommended by the Information Collection Rule for evaluating membrane treatment. All three methods were tested on a small (155‐cm2 [26‐sq‐in.]) flat sheet of membrane. Both the BaReMT and BaIReMT require a far smaller batch volume of water sample than does the RBSMT. The patterns of flux decline and recovery were similar in the BaReMT and RBSMT that used water treatment plant samples from Durham and Fayetteville, N.C. The fouling tendencies of water treatment plant samples from Durham, Fayetteville, and Raleigh, N.C. were similar. Although the mass of natural organic matter on the membrane was small, its estimated concentration in the foulant layer was large. Scanning electron and atomic force micrographs showed that not all foulants were removed from the membrane surface despite extensive cleaning. Only repeated cycles of cleaning can demonstrate the long‐term effect of the remaining foulants on flux recovery.
Sydney's 1998 water quality crisis
Authors: Clancy Jennifer L.
Published: February 2018

Events in Sydney, Australia, illustrate the pitfalls of overreliance on pathogen monitoring data in making decisions about water treatment and public health.

A drinking water quality crisis occurred in Sydney, Australia, from July through September 1998. High concentrations of Cryptosporidium oocysts and Giardia cysts were repeatedly observed in water samples collected in the distribution system, although no increase in waterborne disease was detected. The reported concentrations of both cysts and oocysts ranged from nondetects to thousands of parasites per 100 L of finished water. Based on these monitoring data, three boil‐water advisories were issued over a nine‐week period. A formal government inquiry was ordered to investigate the cause of the contamination. The author visited the facilities involved and found that the laboratory providing the monitoring data had significant quality assurance and quality control problems, rendering the protozoan data suspect. Furthermore, data from other laboratories indicated the original reports were in error. In the author's opinion, reliance on poor‐quality monitoring data created a water quality crisis when, in fact, no water quality problems or threats to public health existed.
Secondary effects of enhanced coagulation and softening
Authors: Carlson Ken , Via Steve , Bellamy Bill , Carlson Mark
Published: February 2018

Enhanced coagulation and softening—while reducing the formation of DBPs—have secondary effects on water treatment processes that must be considered.

The implementation of enhanced coagulation or enhanced softening, while reducing the formation of disinfection by‐products, will affect other treatment processes as a result of the associated changes in water chemistry and solids loading. Utilities that implement enhanced coagulation or softening will likely see secondary effects, which need to be anticipated and mitigated. The AWWA Water Industry Technical Action Fund sponsored an expert workshop with representatives from the utility, consulting, academic, and regulatory fields to identify and characterize the secondary effects of enhanced coagulation and softening and to recommend mitigation strategies. Workshop participants identified four process areas that could potentially be affected by the implementation of an enhanced coagulation or a softening process. Mitigation flowcharts are provided for each secondary effect to help utilities determine what if any course of action to pursue if enhanced coagulation or softening is implemented.
Detecting breaks in prestressing pipe wire
Authors: Atherton David L. , Morton Keith , Mergelas Brian J.
Published: February 2018

A new electromagnetic technique for inspecting prestressed concrete pressure pipe enables nonintrusive inspection for even single broken prestressing wires.

Prestressed concrete pressure pipe (CPP) is in widespread use throughout Canada and the United States, with a total of some 19,000 mi (30,000 km) of pipe in use in North America's major water utilities. Many of these lines are more than 50 years old, and half are expected to need repair or replacement over the next 20 years. To selectively maintain these lines and avoid costs from catastrophic pipe failures, utilities needed an inspection technique that was highly sensitive, reliable, effective, and economical. An innovative electromagnetic technique, based on the remote field eddy current (RFEC) inspection technique, has been developed that allows nonintrusive inspection of prestressed CPP. Full‐scale testing conducted on embedded cylinder pipes and bar‐wrapped pipelines demonstrated the new RFEC technique's sensitivity to both single and multiple breaks in prestressing wire.
Locating leaks with acoustic technology
Authors: Tafuri Anthony N.
Published: February 2018

Researchers were able to pinpoint leaks as small as 0.1 gph using acoustic emission techniques.

Many water distribution systems in this country are almost 100 years old. About 26 percent of piping in these systems is made of unlined cast iron or steel and is in poor condition. Many methods that locate leaks in these pipes are time‐consuming, costly, disruptive to operations, and unreliable at finding small leaks. This article presents the results of research conducted at the US Environmental Protection Agency's Urban Watershed Research Facility in Edison, N.J. The project sought ways to use acoustic technology to pinpoint leaks as small as 0.1 gph (0.1 mL/s) in petroleum pipelines, a regulatory requirement for those lines. Because all experiments were conducted using water and on pipelines of size and material similar to those found in many water distribution systems, results also apply to these pipelines. Although leaks of 0.1 gph (0.1 mL/s) are unusually small to search for in water distribution systems, researchers were able to locate small leaks within 1 ft (0.3 m), which is comparable to the best practice of commercially available leak‐pinpointing technology for water distribution systems.
The blue water phenomenon
Authors: Edwards Marc , Jacobs Sara , Taylor Russell J.
Published: February 2018

Little is known for certain about the factors that initiate or propagate blue water, a perplexing copper corrosion problem.

Extensive effort has been expended by utilities, consultants, and scientists to better understand factors causing outbreaks of blue water, a rare problem that occurs in relatively high pH drinking water. This work synthesizes information about initiation factors, remedial measures, and theories. Although chlorine is an effective remedial measure, little is known for certain about factors that initiate or propagate blue water.
Consumer response to public notification
Authors: Harding Anna K. , Anadu Edith C.
Published: February 2018

A recent study offers utilities information that may help increase the effectiveness of their public notification programs.

Residents of four Oregon communities were surveyed about their responses to public notification. In the two towns that had issued public notification in response to a water problem, most residents were aware of the notices and responded by boiling their water, drinking bottled water, or both. Residents in the town with a short‐term water problem were more likely than residents in the town with a long‐term problem to boil water. Most respondents in both towns favored drinking bottled water over boiling water, despite a boil‐water notice. The survey found that residents of these towns as well as those in two control communities considered the newspaper the primary source of information about their drinking water. The sources of information regarded as most reliable, however, were mail from the city water utility, followed by the county health department and newspapers. Most respondents reported they were willing to pay for drinking water improvements, particularly to correct chemical and microbiological contamination.
The plain, hard truth about pathogen monitoring
Authors: Allen Martin J. , Clancy Jennifer L. , Rice Eugene W.
Published: February 2018

As a pretense for public health protection, pathogen monitoring is of little value and should be replaced by alternative strategies such as treatment optimization.

Pathogen monitoring has concerned microbiologists for nearly a century. Over several years, numerous factors have inflated the value of pathogen monitoring for public health protection and led to such developments as the promulgation of the Information Collection Rule (ICR). Eighteen months of ICR data have only served to underscore the monitoring method's limitations. Methods 1622 and 1623 represent significant improvements but still fall short of providing information useful for compliance monitoring or public health decision‐making. To illustrate the shortcomings of pathogen monitoring, the authors cite recent cases in which poor‐quality analyses contributed to the creation of drinking water crises where none, in fact, existed. The authors propose that pathogen monitoring for protecting public health be replaced by alternative strategies such as optimizing treatment and maintaining water quality throughout storage and distribution.
Giardia and Cryptosporidium occurrence in groundwater
Authors: Moulton‐Hancock Carrie , Rose Joan B. , Vasconcelos G.J. , Harris Stephanie I. , Klonicki Patricia T. , Sturbaum Gregory D.
Published: February 2018

Analysis of groundwater for the presence of microbiota offers researchers a way to estimate the potential for Giardia and Cryptosporidium contamination.

A total of 383 groundwater samples from 166 different sites were analyzed for Cryptosporidium, Giardia, and other microbiota (1–500 μm) using immunofluorescence assay and light microscopy procedures. Analysis of the data showed 11 percent of the sites (19 of 166) were sometimes positive for Cryptosporidium, Giardia, or both. Statistical analyses determined that microbiota in eight major groups were indicative of Cryptosporidium and Giardia contamination. These groups include algae, arthropods, rotifers, fungi, nematodes, colorless flagellates, amoebae, and gastrotrichs. Cryptosporidium and Giardia occurrence also correlated positively with the three risk categories developed by the US Environmental Protection Agency to rank direct surface water influence on groundwaters (p = 0.001). However, the specific numerical scores used to determine risk categories provided no better prediction of the pathogens than the three general categories. To determine vulnerability to contamination, researchers first should investigate those groundwater sources with a diversity of microbiota.
Conventional and optimized coagulation for NOM removal
Authors: Bell‐Ajy Kimberly , Abbaszadegan Morteza , Ibrahim Eva , Verges Debbie , LeChevallier Mark
Published: February 2018

Bench‐ and full‐scale experiments were conducted to evaluate the optimal coagulation conditions for removal of total organic carbon and disinfection by‐products.

The evaluation of 16 sites with optimized coagulation (optimizing the pH of coagulation and then the coagulant dosage) provides an assessment of this coagulation technique and illustrates its capabilities to meet the requirements of the Disinfectants/Disinfection By‐products (D/DBP) Rule. Jar tests were used to determine the effectiveness of optimized coagulation for the removal of organic carbon, DBP precursors, particles, and turbidity when supernatant results were compared with conventional (baseline) treatment. Jar‐test results indicate that optimized coagulation can enhance the removal of organic carbon and DBP precursors.
Using Coagulants to remove organic matter
Authors: Exall Kirsten N. , Vanloon Gary W.
Published: February 2018

This study examined removal of organic matter (OM) by coagulation in drinking water treatment. First, the ability of three coagulants to simultaneously reduce turbidity and remove OM from water was determined. The coagulants tested were the commercial products alum and polyaluminum chloride (PACl) and a polyaluminum hydroxysulfate (PAHS) synthesized in the authors' laboratory. Tannic, humic, lignosulfonic, and salicylic acids (SAL) were used as model organic compounds in cold and warm water. The effect of the concentration of tannic acid was also examined, and semiquantitative relationships between OM concentration and coagulant dosage required were determined. In cold water, PACl and PAHS were efficient coagulants for all organic compounds except SAL (which was not itself removed, although it did not inhibit turbidity reduction). However, alum was a poor coagulant in the presence or absence of OM. In warm water, alum and PACl were the more efficient coagulants. OM had approximately the same effect on alum at both temperatures, but its effect on PACl was somewhat increased in warm water. Although PAHS effectively reduced turbidity in the absence of OM or in the presence of SAL, the presence of the other organic substances greatly increased the coagulant demand in warm water.
Riverbank Filtration: An Overview
Authors: Kuehn Wolfgang , Mueller Uwe
Published: February 2018

Although not widely used by utilities in the United States, bank filtration has been successfully practiced by German water providers for many years. This paper describes their experience, which indicates that bank filtration is a suitable technology for river water under certain conditions. Because it replaces or supports other treatment, bank filtration can help reduce costs for utilities using river water. Because it is a natural process, bank filtration wins support from consumers who want safe, but not highly treated, drinking water supplies.
ozone/biofiltration for removing MIB AND GEOSMIN
Authors: Nerenberg Robert , Rittmann Bruce E. , Soucie William J.
Published: February 2018

A serious and increasingly frequent problem that water utilities face is the occurrence of tastes and odors in drinking water. One of the most common and problematic types of tastes and odors is the musty/earthy type caused by 2‐methylisoborneol (MIB) and trans‐1,10‐dimethyl‐trans‐9‐decalol (geosmin). Common taste and odor treatment methods such as powdered activated carbon, chlorine oxidation, and potassium permanganate oxidation are largely ineffective for reducing these compounds. Fortunately, ozonation followed by biofiltration can provide a well‐suited and effective treatment combination. Ozonation provides at least partial removal of MIB and geosmin, but it also creates undesirable biological instability. Subsequent biofiltration can remove residual MIB and geosmin while at the same time removing the biological instability. A preliminary investigation at a full‐scale treatment plant indicates that the ozonation/biofiltration tandem can effectively reduce MIB to below threshold concentrations and that biofiltration plays an important role in this reduction.
Using indigo absorbance to calculate the indigo sensitivity coefficient
Authors: Gordon Gilbert , Gauw Renee D. , Miyahara Yuko , Walters Bryan , Bubnis Bernard
Published: February 2018

The standard method for measuring residual ozone (O3) is based on the decolorization of indigotrisulfonate at 600 nm using a sensitivity coefficient of 0.42 L mg–1cm–1 (ε ~ 20,000 M–1cm–1). The sensitivity coefficient for a source of indigo is calculated following a time‐consuming and labor‐intensive O3 calibration. In contrast, the data presented in this article show that a simple initial absorbance measurement can be used to calculate the indigo sensitivity coefficient, thereby eliminating the need for O3 calibration when routine measurements are made. The molar absorptivity for seven sources of indigo ranged from 15,800 to 20,355 M–1cm–1. These results indicate that indigo purity (and stability) is potentially a significant source of measurement error when unvalidated indigo stock solutions are used to measure O3. The authors describe indigo solution decomposition and offer a simple initial absorbance method for validating the O3 sensitivity coefficient.
Waterborne Diseases in Europe—1986–96
Authors: Kramer Michael H. , Quade Gustav , Hartemann Philippe , Exner Martin
Published: February 2018

This study evaluated the current status of surveillance for waterborne diseases in European countries and characterized the epidemiology of these diseases and outbreaks. Data gathered through surveillance systems for waterborne disease outbreaks helped researchers identify the agents responsible for these outbreaks and determine why the outbreaks occurred. The authors believe that if such information was collected in a standardized way, it could be used to compare the incidence of waterborne disease outbreaks in different countries and the possible influence of various approaches in water treatment technologies.
Occurrence of perchlorate IN DRINKING WATER SOURCES
Authors: Gullick Richard W. , Lechevallier Mark W. , Barhorst Twila S.
Published: February 2018

Perchlorate is of concern to drinking water suppliers because of its potential risk to human health, tendency to disperse rapidly in groundwater, and resistance to conventional water treatment processes. An occurrence survey was performed in 1997 and 1998 to assess the prevalence of perchlorate in surface and subsurface drinking water supplies of the American Water System. The survey examined 40 surface water sites in 11 states and 367 groundwater wells in 17 states. No perchlorate was detected in any of the surface waters. The presence of perchlorate was confirmed in nine (~2.5%) wells, all located in California or New Mexico. Positive perchlorate concentrations ranged from < 4 to ~7 μg/L, well below the health advisory guideline value of 18 μg/L suggested by the California Department of Health Services. These results help confirm previous reports that perchlorate contamination is a localized problem affecting sites near military‐related facilities or other major sources of perchlorate.
Implications of an MTBE odor study for setting drinking water standards
Authors: Stocking Andrew J. , Suffet Irwin H. , McGuire Michael J. , Kavanaugh Michael C.
Published: February 2018

In early 2001, the US Environmental Protection Agency is expected to adopt a secondary maximum contaminant level (SMCL) for methyl tertiary butyl ether (MTBE) in drinking water. This article presents the first and only consumer study to determine the odor threshold of MTBE in drinking water. A protocol, based on the American Society for Testing and Materials method E679–91, was augmented to address concerns raised by interested stakeholders. The study, which was conducted according to the final odor threshold protocol, used a panel of 57 consumers and yielded an odor threshold for MTBE in drinking water of 15 μg/L. The 15 μg/L threshold is the geometric mean of the individual thresholds for each of the 57 consumers. This consumer panel threshold is consistent with the trained panel thresholds reported from five other taste and/or odor studies, which ranged from 13.5 to 45.5 μg/L. Consequently, the authors recommend using the methodology presented in this article as the scientific basis for establishing the federal SMCL for MTBE and other organic chemicals in drinking water.
Disinfection of Cryptosporidium parvum WITH polychromatic UV light
Authors: Mofidi Alexander A. , Baribeau Hélène , Rochelle Paul A. , De Leon Ricardo , Coffey Bradley M. , Green James F.
Published: February 2018

Bench‐scale experiments determined the germicidal effects of varying dosages of polychromatic ultraviolet (UV) radiation on oocysts of Cryptosporidium parvum. C. parvum oocysts suspended in treated surface water were irradiated with polychromatic light emitted by either a medium‐pressure, continuous‐wave UV lamp or a pulsed‐UV lamp then assayed with human cell culture techniques. Experiments conducted using pulsed‐UV doses of ≥ 16 mJ/cm2 provided > 2‐log inactivation of suspended oocysts of C. parvum. Experiments at lower UV dosages established a dose‐response relationship with both the medium‐pressure and pulsed‐UV lamps. When disinfection results from both light sources were compared on an equivalent dosage basis, no statistical difference in disinfection power was found between the medium‐pressure and pulsed‐UV lamps. Results from both lamps showed that UV doses as low as 7.5 and 11 mJ/cm2 provided inactivation of infectious oocysts of C. parvum at rates of 1 log (90%) and 2 log (99%), respectively. The authors also examined UV disinfection of heterotrophic bacteria and Escherichia coli. They found the response of heterotrophic bacteria to be statistically different from that of C. parvum, whereas E. coli's response to UV light did not statistically differ from that of C. parvum. This suggests that E. coli may be a surrogate organism for C. parvum disinfection provided by UV technologies.
Assessing the vulnerability of groundwater sources to fecal contamination
Authors: Fujioka Roger S. , Yoneyama Bunnie S.
Published: February 2018

The Honolulu Board of Water Supply (HBWS) selectively chlorinates half of its groundwater supply to provide drinking water that meets the Total Coliform Rule. The objective of this study was to determine whether the groundwater sources used by HBWS are vulnerable to contamination with fecal matter and would require routine disinfection. Larger volumes (1,000 mL) of samples from groundwater and from the distribution system were more sensitive than standard volumes (100 mL) in the detection for total coliform, fecal coliform, Escherichia coli, and fecal streptococcus. Confirmed fecal indicator bacteria were detected in 2 of 79 groundwater samples and from none of the 152 distribution system water samples, indicating that the groundwater has a low incidence of contamination and the selective chlorination program effectively reduces this level of contamination. Analysis of 1,000‐mL samples of groundwater is recommended but is not included in the recent guidelines of the proposed Ground Water Rule.
Comparing Cryptosporidium AND MS2 Bioassays—implications for UV Reactor validation
Authors: MaCkey Erin D. , Hargy Thomas M. , Wright Harold B. , Malley James P. , Cushing Robert S.
Published: February 2018

The use and selection of microbial surrogates to validate ultraviolet (UV) reactor performance remain a challenge. Proper interpretation of bioassay results requires an appreciation of the relative UV dose–response of the surrogate and target organisms and the limitations surrogates impose. The aim of this study was to improve the understanding of MS2 coliphage's use as a bioassay surrogate for the waterborne pathogen Cryptosporidium parvum. Side‐by‐side MS2 and Cryptosporidium bioassays were performed to directly link MS2 and Cryptosporidium inactivation. At a flow rate of 757 L/min (200 gpm), the low‐pressure, high‐output UV reactor provided > 4.7‐log Cryptosporidium inactivation at an MS2 equivalent dose of 45 mJ/cm2. Although these data support the use of MS2 as a test organism to validate UV reactor performance, MS2 is a very conservative surrogate for Cryptosporidium. Use of a test organism with a more comparable UV dose–response would allow validation of much higher levels of log inactivation.
Optimizing ferric sulfate coagulation of algae with streaming current measurements
Authors: Briley David S. , Knappe Detlef R.U.
Published: February 2018

This study sought to determine ferric sulfate coagulation conditions that lead to effective removal of algae by conventional gravity sedimentation. Using laboratory‐cultured Anabaena flos‐aquae spiked into natural water, charge titrations and jar tests were conducted to evaluate the effects of streaming current value, coagulation pH, and initial algae concentration on the removal of algae, turbidity, and natural organic matter. At pH 6, ferric sulfate doses corresponding to the point of zero charge (PZC), as determined by streaming current measurements, consistently produced low settled water algae concentrations when an anionic flocculant aid was added. In contrast, ferric sulfate coagulation at pH 7.0 and 7.5 was not effective for algae removal because the algae's surface charge could not be sufficiently neutralized. At pH 6 and the PZC, settled water algae concentrations, turbidity, and ultraviolet absorbance at 254 nm were similar for tests conducted at initial algae concentrations of 10,000 and 50,000 cells/mL, but a larger coagulant dose was required to reach the PZC at the higher initial algae concentration. Thus, adjusting coagulant doses based on streaming current value should be effective for maintaining settled water quality in plants that treat waters with rapidly varying influent algae concentrations and/or background water quality. Experiments conducted with a natural algae bloom sample confirmed that ferric sulfate coagulation at pH 6 and the PZC was effective for algae removal.
ATR–FTIR detection of ≤ 25 μg/L Aqueous Cyanide, Perchlorate, and PFOS
Authors: Strauss Steven H. , Odom Matthew A. , Hebert Gretchen N. , Clapsaddle Brady J.
Published: February 2018

Attenuated total reflectance–Fourier transform infrared (ATR–FTIR) sensors have been developed that can detect polyatomic anions in aqueous solution in the micrograms‐per‐litre range. The ability to detect and potentially quantify aqueous anions is important for several applications including groundwater, surface water, and wastewater testing. The surface of a commercially available ATR crystal was modified with highly selective films of organometallic extractants, resulting in sensitivity enhancements of three to five orders of magnitude relative to the unmodified crystal. No pretreatment of the aqueous solution was required for the detection and identification of three analytes. Detection limits for cyanide, perchlorate, and perfluorooctylsulfonate using the modified crystal were 5, 3, and 25 μg/L, respectively, for 60‐min analyses. The significance of this work is the prospect that a common and easily portable spectroscopic technique can be used to detect and identify aqueous anions at microgram‐per‐litre concentrations—in favorable cases even in the presence of competing anions.
Regulatory Compliance Planning TO ENSURE WATER SUPPLY SAFETY
Authors: Pontius Frederick W.
Published: February 2018

The terrorist attacks on Sept. 11, 2001, caused a sea change in the sense of safety and protection that most Americans felt regarding the threat of externally imposed harm. This article, which is JOURNAL AWWA's annual review of the US Environmental Protection Agency's (USEPA's) drinking water regulatory agenda under the Safe Drinking Water Act, has been expanded to include emergency planning that incorporates responses to both natural disasters and the deliberate introduction of contaminants into a water supply.
Using BAC for HAA removal PART 1: BATCH STUDY
Authors: Zhou Haojiang (“Joe”) , Xie Yuefeng F.
Published: February 2018

The stability and biodegradation of haloacetic acids (HAAs) in the presence of bioactivity were evaluated using batch experiments; a separate experiment assessed the carbon adsorption capacities of HAAs. HAAs were significantly degraded in dechlorinated drinking water in the presence of suspended bacteria. Increasing the number of halogen atoms on an HAA decreased its biodegradation rate but increased its carbon adsorption capacity; increasing the number of bromine atoms on an HAA also increased its carbon adsorption capacity. Biologically active carbon effectively removed milligram‐per‐litre–level HAAs spiked in dechlorinated drinking water. This removal may be a result of the combination of carbon adsorption and biodegradation and can be described by a pseudo first‐order reaction model. The findings from this study are significant for sample preservation for HAA monitoring and could lead to the development of an innovative technology for HAA control in drinking water.
Building the future
Authors: Stovall Lynn
Published: February 2018

Incoming AWWA President Lynn Stovall talks with Journal AWWA Editor Marcia Lacey about the utility of the future, AWWA's achievements and challenges, and plans for his term in office.
Phosphate inhibitor use at US utilities
Authors: McNeill Laurie S. , Edwards Marc
Published: February 2018

Surveys of US drinking water utilities were conducted in 1994 and 2001 to investigate trends in phosphate inhibitor use. More than half of those water providers surveyed reported adding phosphate inhibitors to their water. Zinc orthophosphate and polyphosphate were commonly used inhibitors, and a shift from poly/orthophosphate blends to orthophosphate was observed from 1994 to 2001. Inhibitor doses ranged from < 0.2 to > 3 mg/L as PO4 (although many utilities could only report dosages “as product” because of the proprietary nature of the inhibitor chemicals). Surprisingly, most utilities based their inhibitor selection on limited information, with smaller utilities relying more on nontechnical information (e.g., vendor information, success of the chemical at another utility) than on direct confirmation of the inhibitor's effectiveness. Many utilities are aware of potential drawbacks of inhibitors, especially increased biological activity and more treatment costs and residuals.
Effectiveness of High pH in Controlling Nitrification
Authors: Skadsen Janice
Published: February 2018

Nitrification affects many utilities that use chloramine as the finished water disinfectant, degrading water quality in the distribution system. Control of nitrification is a challenge for these utilities, and traditional nitrification‐control strategies are not always effective. In many cases, the utility must free‐chlorinate the distribution system to handle nitrification water quality problems, defeating the purpose of chloramination—to avoid regulatory problems with disinfection by‐products (DBPs). Utilities need additional nitrification control strategies. This study evaluated historical water quality data and nitrification occurrence at the Ann Arbor (Mich.) Water Plant (AAWP) and identified a correlation between high drinking water pH and the absence of nitrification. AAWP then performed experiments to evaluate the effects on nitrification of maintaining the finished water at pH 8.5 versus 9.4. The higher pH appeared to inhibit nitrification. AAWP then undertook an eight‐year assessment using high pH as an operational parameter. Significant nitrification was not observed in seven of the eight years, whereas in the four years preceding the assessment, when the finished water was pH 8.7–8.9, nitrification occurred every summer. Elevating the pH of the finished water reduced the frequency of nitrification in Ann Arbor—reducing the need to free‐chlorinate the distribution system (and the production of DBPs) and maintaining the chloramine residual in the distribution system.
a taste and odor episode CAUSED BY 2,4,6‐TRIBROMOANISOLE
Authors: Malleret Laure , Bruchet Auguste
Published: February 2018

This case study details the deterioration of drinking water organoleptic quality in a distribution system by the apparition of a musty taste soon after a storage tank was recoated. Because this case could not be elucidated by the closed‐loop stripping analysis followed by gas chromatography–mass spectrometry analyses, the newer and more sensitive large‐volume gas chromatography–mass spectrometry technique was used. Chemical, sensory, and microbiological analyses were carried out to identify the compounds involved, their mechanism of formation, and their origin in the distribution system. The musty taste in drinking water was attributed to the presence of 2,4,6‐tribromoanisole (2,4,6‐TBA). This compound originated from 2,4,6‐tribromophenol (2,4,6‐TBP), which might have been metabolized to 2,4,6‐TBA by fungi living in the mass of the coating. Although the authors were unable to conclusively trace the origin of 2,4,6‐TBP, the study clearly showed that the odor in the drinking water was caused by leaching from the coating.