Control of Microbial Water Quality in the Little Rock, Arkansas Distribution System

by Bruno Kirsch, Jr., Little Rock Municipal Water Works, Little Rock, United States,
Craig Noble, Little Rock Municipal Water Works, Little Rock, United States,
Christopher H. Yu, Little Rock Municipal Water Works, Little Rock, United States,
Blaise J. Brazos, Little Rock Municipal Water Works, Little Rock, United States,
John T. O'Connor, Little Rock Municipal Water Works, Little Rock, United States,



Document Type: Proceeding Paper

Part of: Critical Issues in Water and Wastewater Treatment

Abstract:

Beginning in the summer of 1993, seasonal studies were undertaken to evaluate the effectiveness of water treatment processes at Little Rock Municipal Water Works (LRMWW). Two treatment facilities were evaluated for the removal of total bacteria and the growth of bacteria during distribution. In addition to conventional data on coliform and heterotrophic plate count (HPC), total bacterial cell counts were used to evaluate seasonal changes in influent (lake water), treatment plant performance for bacterial removal and microbial populations and growth during distribution. The persistence of disinfectant residuals in finished water and in distributed water was also observed to complement data on microbial populations. Chlorine demand studies were conducted in chlorine-demand-free glass containers to observe the persistence of chlorine versus chloramine. These studies were replicated under cold (4?C) and warm (24?C) temperature conditions. Each of the two treatment plant finished waters plus water from a location in the distribution system were evaluated in this series. Non-purgeable organic carbon (NPOC) concentrations were monitored seasonally in the source waters and in both treatment plant effluents. Changes in NPOC during distribution were assessed with respect to the maintenance of disinfectant residuals and the control of bacterial growth during distribution. Overall, the data collected formed the basis for recommendations on the control of microbial quality in the Little Rock water distribution system. The results also form the basis for a new, comprehensive, year-long pilot plant study to be initiated early in 1994.

Subject Headings: Water treatment plants | Water quality | Water treatment | Bacteria | Water supply systems | Municipal water | Chlorine | Arkansas

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