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OZONATION AND BIOLOGICAL STABILITY OF WATER IN AN OPERATING WATER TREATMENT PLANT
Citation:
Reasoner, D., E.W. Rice, AND L. Fung. OZONATION AND BIOLOGICAL STABILITY OF WATER IN AN OPERATING WATER TREATMENT PLANT. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/D-90/228 (NTIS PB91162488), 1990.
Description:
Ozonation of drinking water may adversely affect the biological stability of the inished water. his study was designed assess the effect of ozone as a preoxidant on the nutrient status of water treated in a full-scale water treatment plant. he study was conducted over a ten week period with analyses performed on a weekly basis. he Haworth Water Treatment Plant is a direct filtration plant utilizing ozonation, alum and cationic polymer flocculation, flotation-skimming, and dual media (anthracite-sand) filtration. hlorine is added just prior to the filtration process to maintain a residual in the filter effluent. hlorine and ammonia are added after filtration to produce a chloramine residual in the finished water. amples collected were the raw source water, water from the ozone contactor, and the finished product water collected at the entry point of the distribution system. Standard water quality parameters analyzed included total coliform bacteria, heterotrophic place count bacteria, total organic carbon (TOC), pH, turbidity, hardness, alkalinity, specific conductance, sulfate, nitrate and chloride. iological stability of the water was determined by the assimilable organic carbon (AOC) bioassay using Pseudomonas fluorescens strain P-l7 and Spirillum strain NOX, and by the coliform growth response (CGR) bioassay with Enterobacter cloacae and Escherichia coli as the bioassay organisms. OC values increased only minimally through the treatment chain. he AOC levels in the finished water averaged greater than 200 ug C-eq/L. OC levels were unreliable for predicting microbiological growth. he CGR for E. coli was consistently negative, but the E. cloacae CGR increased after ozonation and was only minimally reduced after filtration. OC measured by the dual organism bioassay (P-17 + NOX) increased in the water post-filtration, suggesting that chlorination to maintain a residual in the filter effluent caused the release of AOC from the dual media filters.
