Mixing in Distribution System Storage Tanks: Its Effect on Water Quality

Clark, Robert M.; Abdesaken, Farzaneh; Boulos, Paul F.; Mau, Russell E.

doi:10.1061/(asce)0733-9372(1996)122:9(814)

Cited by 45 publications

(24 citation statements)

References 9 publications

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“…Amblard et al (1996) documented seasonal differences in the microbial community structure of a drinking water reservoir. Clark et al (1996) emphasized the importance of distribution system storage tanks as a possible source of bacteria to the drinking water distribution system. They noted that the long residence time of water in storage tanks can have a negative impact on water quality including the loss of chlorine and regrowth of microbes.…”

Section: Introductionmentioning

confidence: 99%

An Analytical Method for Trifluoroacetic Acid in Water and Air Samples Using Headspace Gas Chromatographic Determination of the Methyl Ester

Zehavi

Seiber

1996

Anal. Chem.

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An analytical method has been developed for the determination of trace levels of trifluoroacetic acid (TFA), an atmospheric breakdown product of several of the hydrofluorocarbon (HFC) and hydrochlorofluorocarbon (HCFC) replacements for the chlorofluorocarbon (CFC) refrigerants, in water and air. TFA is derivatized to the volatile methyl trifluoroacetate (MTFA) and determined by automated headspace gas chromatography (HSGC) with electron-capture detection or manual HSGC using GC/MS in the selected ion monitoring (SIM) mode. The method is based on the reaction of an aqueous sample containing TFA with dimethyl sulfate (DMS) in concentrated sulfuric acid in a sealed headspace vial under conditions favoring distribution of MTFA to the vapor phase. Water samples are prepared by evaporative concentration, during which TFA is retained as the anion, followed by extraction with diethyl ether of the acidified sample and then back-extraction of TFA (as the anion) in aqueous bicarbonate solution. The extraction step is required for samples with a relatively high background of other salts and organic materials. Air samples are collected in sodium bicarbonate-glycerin-coated glass denuder tubes and prepared by rinsing the denuder contents with water to form an aqueous sample for derivatization and analysis. Recoveries of TFA from spiked water, with and without evaporative concentration, and from spiked air were quantitative, with estimated detection limits of 10 ng/mL (unconcentrated) and 25 pg/mL (concentrated 250 mL:1 mL) for water and 1 ng/m(3) (72 h at 5 L/min) for air. Several environmental air, fogwater, rainwater, and surface water samples were successfully analyzed; many showed the presence of TFA.

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Section: Introductionmentioning

confidence: 99%

An Analytical Method for Trifluoroacetic Acid in Water and Air Samples Using Headspace Gas Chromatographic Determination of the Methyl Ester

Zehavi

Seiber

1996

Anal. Chem.

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“…Similarly, increasing overhead storage for surge protection (e.g., closed tank, open standpipe, feed tank, bladder tank) can result in long residence times, which in turn may contribute to water quality deterioration. These effects include chlorine residual loss and possible increases in the level of microorganisms (Clark et al, 1996). Proper operation and maintenance of these storage facilities are required to avoid poor quality water from entering the distribution system.…”

Section: Consequences Of Transientsmentioning

confidence: 99%

Hydraulic Transient Guidelines for Protecting Water Distribution Systems

Boulos¹,

Karney²,

Wood³

et al. 2005

Journal AWWA

Self Cite

140

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Transients can introduce large pressure forces and rapid fluid accelerations into a water distribution system. These disturbances may result in pump and device failures, system fatigue or pipe ruptures, and even the backflow/intrusion of dirty water. Many transient events can lead to water column separation, which can result in catastrophic pipeline failures. Thus, transient events cause health risks and can lead to increased leakage or decreased reliability. Transient flow simulation has become an essential requirement for ensuring safety and the safe operation of drinking water distribution systems. This article provides a basic understanding of the physical phenomena and context of transient conditions, presents practical guidelines for their suppression and control, and compares the formulation and computational performance of widely used hydraulic transient simulation schemes. Such capabilities greatly enhance the ability of water utilities to conceive and evaluate cost-effective and reliable water supply protection and management strategies and safeguard public health.A 112 MAY 2005 | JOURNAL AWWA • 97:5 | PEER-REVIEWED | BOULOS ET AL sient pressures are most important when the rate of flowis changed rapidly, such as resulting from rapid valve closures or pump stoppages. Such disturbances, whether caused by design or accident, may create traveling pressure and velocity waves of large magnitude. These transient pressures are superimposed on the steady-state conditions present in the line at the time the transient pressure occurs. The severity of transient pressures must be determined so that the water mains can be properly designed to withstand these additional loads. In fact, pipes are often characterized by their "pressure ratings" that define their mechanical strength and have a significant influence on their cost.

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“…It is well‐recognized that pressure transients may adversely affect the quality of treated water. Pressure transients in water distribution systems result from an abrupt change in the flow velocity and can be caused by main breaks, sudden changes in demand, uncontrolled pump starting rine residual loss and possible increases in the concentration of microorganisms (Clark et al, 1996). Pathogens can also enter the distribution system during construction, repair, cross‐connections, and conditions and activities in which the system is open to the atmosphere or the environment (Karim et al, 2003).…”

Section: Pressure Transientsmentioning

confidence: 99%

Numerical methods for modeling transient flow in distribution systems

Wood¹,

Lingireddy²,

Boulos³

et al. 2005

Journal AWWA

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The authors compared the formulation and computational performance of two numerical methods for modeling hydraulic transients in water distribution systems. One method is Eulerian-based, and the other is Lagrangian-based. The Eulerian approach explicitly solves the hyperbolic partial differential equations of continuity and momentum and updates the hydraulic state of the system in fixed grid points as time is advanced in uniform increments.The Lagrangian approach tracks the movement and transformation of pressure waves and updates the hydraulic state of the system at fixed or variable time intervals at times when a change actually occurs. Each method was encoded into an existing hydraulic simulation model that gave initial pressure and flow distribution and was tested on networks of varying size and complexity under equal accuracy tolerance. Results indicated that the accuracy of the methods was comparable, but that the Lagrangian method was more computationally efficient for analysis of large water distribution systems.

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Mixing in Distribution System Storage Tanks: Its Effect on Water Quality

Cited by 45 publications

References 9 publications

An Analytical Method for Trifluoroacetic Acid in Water and Air Samples Using Headspace Gas Chromatographic Determination of the Methyl Ester

An Analytical Method for Trifluoroacetic Acid in Water and Air Samples Using Headspace Gas Chromatographic Determination of the Methyl Ester

Hydraulic Transient Guidelines for Protecting Water Distribution Systems

Numerical methods for modeling transient flow in distribution systems

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