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EFFECTS OF MIXING AND AGING ON WATER QUALITY IN DISTRIBUTION SYSTEM STORAGE FACILITIES
Citation:
GRAYMAN, W. M., L. A. ROSSMAN, R. A. DEININGER, C. D. SMITH, C. N. ARNOLD, AND J. F. SMITH. EFFECTS OF MIXING AND AGING ON WATER QUALITY IN DISTRIBUTION SYSTEM STORAGE FACILITIES. JOURNAL OF AMERICAN WATER WORKS ASSOCIATION. American Water Works Association, Denver, CO, 96(9):70-80, (2004).
Description:
Aging of water in distribution system storage facilities can lead to deterioration of the water quality due to loss of disinfectant residual and bacterial regrowth. Facilities should be operated to insure that the age of the water is not excessive taking into account the quality of the water, its reactivity, the type of disinfectant that is used, and the travel time before and after the water's entry into the storage facility.
Mixing processes in such facilities can magnify aging problems by creating zones of older water. To minimize mixing problems, distribution system storage facilities should be designed and operated to encourage good mixing. This differs significantly from clearwells and contact chambers at treatment plants where plug flow is desired in order to produce adequate disinfectant contact time.
Tanks and reservoirs can experience aging and/or mixing problems. These can be interrelated or may be independent problems. The nature of the specific problem should be identified and appropriate design or operational strategies followed to address the problems. For example, if a tank is experiencing excess water age then modifications that address only mixing will have little impact on the underlying problem.