Showing papers in "Journal American Water Works Association in 1991"
425 citations
TL;DR: The Rapid Small Scale Column Test (RSSCT) as mentioned in this paper is a scaled-down version of a pilot or full-scale granular activated carbon (GAC) column.
Abstract: The rapid small-scale column test (RSSCT) is a scaled-down version of a pilot- or full-scale granular activated carbon (GAC) column. Simple equations for selecting the design and operating parameters of RSSCTs from the full-scale process design variables are presented, and their limitations are discussed. Case studies representing high and low levels of synthetic organic chemicals, in the presence and absence of background dissolved organic carbon (DOC), and weakly and strongly adsorbing organics are reviewed
239 citations
TL;DR: Natural polyelectrolytes such as chitosan (cationic) and sodium alginate (anionic) are not only as effective as or even more effective than their counterparts at similar dosages, but they also do not cause any adverse effects to human health as mentioned in this paper.
Abstract: Synthetic polyelectrolytes are widely used in the United States because of their effectiveness as a coagulant or coagulant aid Synthetic polyelectrolytes produce a lower volume of sludge compared with alum flocculation, and their effectiveness is not much affected by the pH level of water Synthetic polyelectrolytes provide better dewatering characteristics in sludge produced and facilitate better filter performance However, one drawback of these products is that their long-term effects on human health are not well understood Natural polyelectrolytes such as chitosan (cationic) and sodium alginate (anionic) are not only as effective as or even more effective than their counterparts at similar dosages, but they also do not cause any adverse effects to human health This article presents results of benchand pilot-scale tests that compared natural and synthetic polyelectrolytes It suggests that natural products would be workable substitutes for synthetic products
157 citations
TL;DR: In this article, the authors developed a means of quantifying the effect of initial activated carbon concentration in different types of waters on its adsorption isotherm, and the method used approximates the complex mixture of BOM with a single equivalent background compound (EBC).
Abstract: One of the main factors affecting the equilibrium capacity of activated carbon for synthetic organic chemicals (SOCs) in natural water is the presence of background organic matter (BOM). However, the initial SOC concentration also plays an important role in determining the capacity of the carbon. The objective of this study was to develop a means of quantifying the effect of initial SOC concentration in different types of waters on its adsorption isotherm. The method used approximates the complex mixture of BOM with a single equivalent background compound (EBC). The initial concentration and single-solute isotherm constants of the EBC were calculated based on the BOM's competitive effect on the adsorption of the SOC on activated carbon. The EBC method was then successfully used to predict the equilibrium capacity of powdered activated carbon for 2,4,6-trichlorophenol in several natural and finished waters when present at different initial concentrations.
138 citations
TL;DR: In this paper, the second-stage granular activated carbon (GAC) filtration is used for this purpose at the Choisy-le-Roi, Paris, France, treatment plant.
Abstract: To maintain the biological stability of drinking water during distribution in large, complex networks, high standards have to be met--namely, low bacterial densities and low levels of biodegradable organic carbon. Second-stage granular activated carbon (GAC) filtration (without regeneration of carbon) is used for this purpose at the Choisy-le-Roi, Paris, France, treatment plant. Effective removal of dissolved organic carbon has been observed with such filtration mainly because of a reduction in the biodegradable organic carbon. To study the microbial processes involved in this removal, new methods based on the use of radio-labeled tracers have been developed in order to measure the bacterial biomass and activity associated with GAC.
132 citations
TL;DR: In this article, the performance of powdered activated carbon (PAC) for uses other than taste and odor control is poorly documented, and the purpose of this article is to critically review uses that have been reported and to analyze means of employing PAC more efficiently.
Abstract: Because the performance of powdered activated carbon (PAC) for uses other than taste and odor control is poorly documented, the purpose of this article is to critically review uses that have been reported and to analyze means of employing PAC more efficiently. The reported removals of trihalomethanes and trihalomethane precursors by PAC range from poor to very good. One of the main advantages of PAC is its low capital cost
130 citations
TL;DR: In this paper, the agronomic and environmental issues are essential before a land-based disposal program is implemented Water treatment sludges may favorably modify the pH and water-holding capacity of soils but generally have little fertilizer value Supplemental phosphorus (P) fertilizer will usually be needed to offset the strong P-binding capacity of these sludgeges.
Abstract: Economic, regulatory, and legal constraints on alternative disposal methods are raising interest in land application of water treatment sludges Understanding the agronomic and environmental issues is essential before a land-based disposal program is implemented Water treatment sludges may favorably modify the pH and water-holding capacity of soils but generally have little fertilizer value Supplemental phosphorus (P) fertilizer will usually be needed to offset the strong P-binding capacity of these sludges Heavy metal concentrations can be limited in sludges primarily by controlling the purity of the coagulant chemicals
126 citations
TL;DR: A powdered activated carbon-ultrafiltration system was examined as an alternative to conventional treatment for removal of bacteria, turbidity, and organic compounds in this article, and the results showed that the system was more effective than conventional treatment.
Abstract: A powdered activated carbon-ultrafiltration system was examined as an alternative to conventional treatment for removal of bacteria, turbidity, and organic compounds
118 citations
TL;DR: In this paper, the authors quantify the kinetics of Mn(II and Fe(II) oxidation by potassium permanganate and chlorine dioxide and illustrate the effects of reduced metal ion concentration, pH, temperature, and the presence of dissolved organic carbon (DOC) on these kinetics.
Abstract: This article describes research to quantify the kinetics of Mn(II) and Fe(II) oxidation by potassium permanganate and chlorine dioxide; illustrates the effects of reduced metal ion concentration, pH, temperature, and the presence of dissolved organic carbon (DOC) on these kinetics; an investigates aspects of oxidation through modeling analyses
96 citations
TL;DR: A case of viral contamination of the water supply at the Arapiles 62 camp, where bacterial indicators were unable to predict the virological quality of the drinking water.
Abstract: This article describes a case of viral contamination of the water supply at the Arapiles 62 camp, where bacterial indicators were unable to predict the virological quality of the drinking water
92 citations
TL;DR: In this paper, the authors quantified the kinetics of Mn(II) sorption by MnOx(s)-coated filter media were quantified as a function of solution pH, Mn Ox(s) surface concentration, and free chlorine concentration of the filter applied water.
Abstract: Research was conducted to provide a better understanding of the mechanisms of Mn(II) removal in oxide-coated filters. The kinetics of Mn(II) sorption by MnOx(s)-coated filter media were quantified as a function of solution pH, MnOx(s) surface concentration, and free chlorine concentration of the filter-applied water. Rate of Mn(II) sorption was positively correlated to the number of available surface adsorption sites within a filter. Free chlorine had a very significant role in defining both the rate and ultimate extent of Mn(II) removal. Addition of chlorine to the filter-applied water oxidized the adsorbed Mn(II), thereby continually regenerating the media surface. In the absence of free chlorine, Mn(II) removal was by adsorption only; no evidence of auto-oxidation of Mn(II) was noted. Practical applications of the work to the operation of water treatment facilities concern the selection of oxidant dosing locations, the impact on filtration hydraulics, and the determination of media generation requirements.
TL;DR: In this paper, the effluents of granular activated carbon contactors were found to have very low assimilable organic carbon concentrations in the effluent of the contactors, while the carbon dioxide concentration was high.
Abstract: Assimilable organic carbon concentrations in the effluents of granular activated carbon contactors were very low.
TL;DR: In this article, a project on the use of ultrafiltration (UF) for particle removal, studies were performed on four different untreated source waters, two from northern California and two from Boise, Idaho.
Abstract: As part of a project on the use of ultrafiltration (UF) for particle removal, studies were performed to evaluate the use of low-pressure hollow-fiber UF as an alternative for complying with Surface Water Treatment Rule (SWTR) requirements for microbial removal and/or inactivation. Pilot studies were conducted on four different untreated source waters, two from northern California and two from Boise, Idaho. Process efficacy was assessed by conducting MS2 virus, total coliform bacteria, and Giardia muris seeding studies, as well as monitoring for naturally occurring bacteria. The study showed that UF was capable of meeting SWTR requirements for alternative filtration technologies without the use of chemical disinfection. Four or more logs of Giardia and more than 6.5 logs of virus were removed from each of the untreated source waters. Differences in water quality or changes in operating parameters did not appear to affect removal capabilities of the process. Maintenance of membrane integrity was critical to assuring process efficacy. When module integrity was compromised, as in fiber breakage, both MS2 virus and G. muris were detected in the permeate. Changes in membrane integrity were not necessarily reflected by changes in permeate turbidity; however, particle counting was an effective method for detecting a compromised membrane module.
TL;DR: A simulated distribution system (SDS) method has been developed to predict the amounts of disinfection by-products (DBPs) that would form in a distribution system as mentioned in this paper.
Abstract: A simulated distribution system (SDS) method has been developed to predict the amounts of disinfection by-products (DBPs) that would form in a distribution system. The parameters (chlorine dosage, incubation temperature, and incubation holding time) of the method are chosen to simulate the conditions of the treatment plant and the distribution system. A study was conducted on the Metropolitan Water District of Southern California's distribution system at a time when free chlorine was being used in the distribution system. A second study was conducted on water from a utility in the eastern United States. Both studies showed good correlation between the SDS samples and the samples collected from the distribution systems.
TL;DR: Waters from seven utilities that use ozone as a preoxidant were analyzed to determine the impact of ozone on the removal of total organic carbon (TOC) and trihalomethane (THM) precursors and on the collision efficiency factor and electrophoretic mobility of suspended particles in the water.
Abstract: Waters from seven utilities that use ozone as a preoxidant were analyzed to determine the impact of ozone on the removal of total organic carbon (TOC) and trihalomethane (THM) precursors and on the collision efficiency factor and electrophoretic mobility of suspended particles in the water
TL;DR: In an effort to determine the viability of various disinfection alternatives, the Evansville, Ind., Water and Sewer Utility is engaged in a pilot-plant investigation to compare chlorine dioxide and ozone pretreatment.
Abstract: In an effort to determine the viability of various disinfection alternatives, the Evansville, Ind., Water and Sewer Utility is engaged in a pilot-plant investigation to compare chlorine dioxide and ozone pretreatment. As a result of increased speculation that the total residual concentration of chlorine dioxide and its inorganic species will soon be regulated, supplemental studies were performed to determine the effectiveness of various reducing agents for reducing or eliminating chlorine dioxide and chlorite ion residuals in finished water
TL;DR: The inactivation kinetics of cell-associated and dispersed hepatitis A virus (HAV) by free chlorine and monochloramine were compared and Cell-associated HAV was always inactivated more slowly than dispersed HAV.
Abstract: The inactivation kinetics of cell-associated and dispersed hepatitis A virus (HAV) by free chlorine and monochloramine were compared Cell-associated HAV was always inactivated more slowly than dispersed HAV Values of C xTor other disinfection criteria for inactivation of HAV and other enteric viruses should be based on viruses associated with cells or other solids because they are better models for the likely state of viruses found in water
TL;DR: To better understand the mode of action of monochloramine, its effect on the structural and physiological integrity of Escherichia coli B was studied and the disinfectant did not severely damage the cell envelope of the bacterium or affect nucleic acid function.
Abstract: To better understand the mode of action of monochloramine, its effect on the structural and physiological integrity of Escherichia coli B was studied. The disinfectant did not severely damage the cell envelope of the bacterium or affect nucleic acid function. Inhibition of typical protein-associated biological activities, e.g., bacterial transport, respiration, and substrate dehydrogenation, were observed at concentrations normally used for disinfection
TL;DR: In this article, the effect of ozonation on particle behavior was investigated under a variety of conditions, including spontaneous particle coagulation, lowered coagulant requirements, and formation of new particles.
Abstract: The effect of ozonation on particle behavior was investigated under a variety of conditions. Spontaneous particle coagulation (particle agglomeration without coagulant addition), lowered coagulant requirements, and formation of new particles were observed in some cases
TL;DR: In this paper, the results of applying ozonation and membrane treatment to a groundwater source containing significant levels of color and disinfection byproduct (DBP) precursors were reported.
Abstract: This article reports the results of applying ozonation and membrane treatment to a groundwater source containing significant levels of color and disinfection by-product (DBP) precursors. The effective DBP precursor removal provided by membrane separation of this groundwater source indicates that membrane processes are a promising treatment technology for complying with the more stringent DBP regulations that are expected in the near future
TL;DR: In this paper, the authors conclude that, at best, the application of polyphosphates for the specific purpose of lead corrosion control entails considerable uncertainty and risk, and they conclude that polyphophosphates are not suitable for this purpose.
Abstract: Lead concentrations in drinking water can be minimized by adjusting the pH and alkalinity. Such lead solubility controls, however, may be offset by other water treatment measures that inadvertently increase lead solubility, e.g., the adding of polyphosphate-containing products. Through the use of solubility computations, the authors of this article conclude that, at best, the application of polyphosphates for the specific purpose of lead corrosion control entails considerable uncertainty and risk.
TL;DR: The authors conclude that regeneration of the resin of the ion exchange column at sulfate breakthrough, in combination with a GAC column, will produce a water very low in THM formation potential.
Abstract: This study investigated the control of trihalomethanes (THMs) with ion exchange by comparing the THM formation potentials of the organic fractions in the influent to three column systems. The results showed that the smallest organic fraction, <0.5K apparent molecular weight (AMW), was most reactive with free available chlorine. With the ion exchange system, the 1-5K-, 0.5-1 K-, and <0.5-AMW organic fractions produced the majority of THMs, whereas with the granular activated carbon (GAC) and the combined ion exchange-CAC systems, the <0.5-AMW fraction produced most of the THMs. The authors conclude that regeneration of the resin of the ion exchange column at sulfate breakthrough, in combination with a GAC column, will produce a water very low in THM formation potential.
TL;DR: In this article, mixed-couple theory is applied to the electrochemistry of the Pb-Sn solder-copper joint and a technique for evaluating corrosion acceleration that is induced by galvanic stimulation is described.
Abstract: This article applies mixed-couple theory to the electrochemistry of the Pb-Sn soldercopper joint and describes a technique for evaluating corrosion acceleration that is induced by galvanic stimulation. The theoretical underpinnings of the analysis are developed, along with an innovative analytical procedure that makes verification of predicted galvanic currents possible. The normal exposure of the soldered joint to water flow rapidly passivates the solder surface and limits galvanic action. After a few days, the ratio of the copper surface to that of the solder is of minimal consequence to corrosion of the solder surface. The pH is an important parameter in determining the rate and extent of passivation of the solder surface, as is the presence of orthophosphate inhibitors. Chlorine residuals are of little importance to the galvanic corrosion process. This research relates to proposed treatment procedures to minimize lead release.
TL;DR: Deininger et al. as mentioned in this paper applied the concept of coverage and inferred the effect of mixing of water from different sources, and provided systematic and quantitative guidelines are provided here for locating monitoring stations.
Abstract: Water undergoes substantial changes in quality between the time it leaves the treatment ities, and distribution system; age, type, plant and the time it reaches the customer’s tap, making it important to select monitoring design, and maintenance of the distribustations that will adequately monitor these changes. But because there is no uniform tion network; and quality of treated water.’ schedule or framework for monitoring under the Safe Drinking Water Act, the degree of Another factor, infrequently considered, variability among monitoring requirements poses both management and technical barriers that may influence water quality in a distrito states and water systems ultimately responsible for implementation of the regulations. bution system is the effect of mixing of Systematic and quantitative guidelines are provided here for locating monitoring stations. water from different sources. Water distriBy using the concept of pathways, the authors applied the concept of coverage and inferred bution systems frequently draw water the quality at an upstream node from the quality at a downstream node. from multiple sources, such as a combinaFinished water may undergo substantial the distribution system itself can have a changes in quality between the time it negative effect on water quality. Some inleaves a treatment plant and the time it fluential factors are chemical and biologireaches the consumer. Most of the inter- cal quality of source water; effectiveness est in water quality has focused on finished and efficiencv of treatment nrocesses: inA demo@ration diskette is available from RolfA. Deininger, School of Public Health, University of Michigan, Ann Arbor, MI 48109. Pleasesendaformatted 1.2-m diskette along with a selfaddressed label and water as it leaves-the treatment plant, but tegrity of the-treatment plan{ storage facil- postage.
TL;DR: Bacteria has also been shown to interfere with the detection of coliform bacteria, and members of the total coliform group of bacteria themselves have been implicated in regrowth problems, thus giving rise to major compliance violations.
Abstract: bacteria has also been shown to interfere with the detection of coliform bacteria. Further, and perhaps most important, members of the total coliform group of bacteria themselves have been implicated in regrowth problems, thus $ving rise to major compliance violations. Bacterial regrowth is affected by a variety of factors. The temperature of the water has been shown to play a major role in bacterial regrowth. An increase in heterotrophic plate count (HPC) organisms has been associated with increasing temperatures following a late spring-summer-autumn sequence in utilities experiencing coliform problems.3 The type of water treatment that is employed by a utility may have a direct impact on microbial growth. It has been demonstrated that the use of ozone in the treatment of water with high humic content, without the subsequent removal of the oxidation products, increases microbial growth in the distribution system.4 This finding is of particular interest because of the proposed increased use of ozonation by water utilities. The incorporation of biological unit processes in water treatment can also affect the nutrient status of the product water. Biological treatment of drinking water, although rarely used in the United States, is common in Europe where the biooxidation of organic matter and ammonia has been demonstrated to be beneficial and cost-efficient. The velocity of water flowing through the mains is an important factor influencing microbial colonization and growth in the distribution system. Pipe sectionswith high water velocities tend to limit microbial protection and reduce sediment accumulation, thus minimizing nutrient entrap ment and protection from exposure to the disinfectant. Conversely, areas of slow flow and dead-end locations have been statistically correlated with water quality deterioration? The presence of iron tubercles has also been associated with microbial growth, especially with colonization by coliform bacteria.6 The maintenance of an adequate disinfectant residual is universally recom
TL;DR: In this paper, an extensive field study by the US Environmental Protection Agency and the North Penn Water Authority resulted in the development of a series of models to investigate contaminant propagation in a water distribution system.
Abstract: This article briefly reviews an extensive field study by the US Environmental Protection Agency and the North Penn Water Authority, which resulted in the development of a series of models to investigate contaminant propagation in a water distribution system. The application of one such model to the exploration of contaminant movement in the distribution network of Cabool, Mo., is explained. An extension of this work to a large water utility - the South Central Connecticut Regional Water Authority - is also discussed.
TL;DR: Dissolved-air flotation (DAF) was compared with conventional gravity settling (CGS) in laboratory experiments using synthetic water and in field studies using alum and polyaluminum chloride.
Abstract: Dissolved-air flotation (DAF) was compared with conventional gravity settling (CGS) in laboratory experiments using synthetic water and in field studies using alum and polyaluminum chloride DAF produced significantly lower residual turbidities than did CGS, particularly at colder temperatures The difference in performance between DAF and CGS is explained using the particle size, particle density, temperature, and settlingrate relations described by Stokes' law In addition, the large bubble volume concentrations released during DAF provided adequate opportunities for collisions between particles and bubbles, thus reducing the need for long flocculation periods DAF achieved good performance with flocculation periods of 5 min, whereas CGS required at least 20 min of flocculation In both processes, dissolved organic species and organic halide precursors were removed to the same degree, and similar levels of residual dissolved aluminum were found
TL;DR: In this article, a comprehensive literature review was undertaken to document other cases of plastic pipe permeation and demonstrated that the majority of such incidents were associated with gross soil contamination in the area surrounding the pipe.
Abstract: Sites of seven incidents of plastic pipe permeation were visited between July 1986 and December 1987, and samples of soil, pipe material, and pipe water were collected. In addition, a comprehensive literature review was undertaken to document other cases of permeation. This work demonstrated that the majority of permeation incidents were associated with gross soil contamination in the area surrounding the pipe. Soil contamination occurred mainly after pipe installation, suggesting that soil analysis prior to pipe installation will not significantly decrease the number of incidents. The occurrence of about half the incidents in low risk areas indicates that limiting plastic pipe use to these areas will not be effective in preventing permeation.
TL;DR: In this paper, historical records were used to characterize the quality of water in an open distribution reservoir with respect to trihalomethanes and total organic halides and explore the effect of algae, chlorine use, and reservoir bypass operation on THM formation.
Abstract: Historical records were used to characterize the quality of water in an open distribution reservoir with respect to trihalomethanes (THMs) and total organic halides and to explore the effect of algae, chlorine use, and reservoir bypass operation on THM formation