bluuebunny/crossref_metadata_2025_split huggingface dataset:
DE filtration to remove Cryptosporidium
Authors: Ongerth Jerry E. , Hutton and P.E. 
Published: February 2018

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

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

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

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

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

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

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

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

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

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