Title

Effect of distribution system materials and water quality on heterotrophic plate counts and biofilm proliferation

Authors

Authors

Y. C. Chang;K. Jung

Comments

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Abbreviated Journal Title

J. Microbiol. Biotechnol.

Keywords

pipe material; biofilm biomass quantification; drinking water; PEPA; FIXED BACTERIAL BIOMASS; EXOPROTEOLYTIC ACTIVITY; CHLORINE PENETRATION; ANTIMICROBIAL AGENTS; DISINFECTION; CORROSION; Biotechnology & Applied Microbiology; Microbiology

Abstract

The biofilms on pipe walls in water distribution systems are of interest since they can lead to chlorine demand, coliform growth, pipe corrosion, and water taste and odor problems. As such, the study described in this paper is part of an AWWARF and Tampa Bay Water tailored collaboration project to determine the effect of blending different source waters on the water quality in various distribution systems. The project was based on 18 independent pilot distribution systems (PDS), each being fed by a different water blend (7 finished waters blended in different proportions). The source waters compared were groundwater, surface water, and brackish water, which were treated in a variety of pilot distribution systems, including reverse osmosis (RO) (desalination), both membrane and chemical softening, and ozonation-biological activated carbon (BAC), resulting in a total of 7 different finished waters. The observations from this study consistently demonstrated that unlined ductile iron was more heavily colonized by a biomass than galvanized steel, lined ductile iron, and PVC (in that order) and that the fixed biomass accumulation was more influenced by the nature of the supporting material than by the water quality (including the secondary residual levels). However, although the bulk liquid water cultivable bacterial counts (i.e. heterotrophic plate counts or HPCs) did not increase with a greater biofilm accumulation, the results also suggested that high HPCs corresponded to a low disinfectant residual more than a high biofilm inventory. Furthermore, temperature was found to affect the biofilms, plus the AOC was important when the residual was between 0.6 and 2.0 mg Cl-2/l. An additional aspect of the current study was that the potential of the exoproteolytic activity (PEPA) technique was used along with a traditional so-called destructive technique in which the biofilm was scrapped off the coupon surface, resuspended, and cultivated on an R2A agar. Both techniques indicated similar trends and relative comparisons among the PDSs, yet the culturable biofilm values for the traditional method were several orders of magnitude lower than the PEPA values.

Journal Title

Journal of Microbiology and Biotechnology

Volume

14

Issue/Number

6

Publication Date

1-1-2004

Document Type

Article

Language

English

First Page

1114

Last Page

1119

WOS Identifier

WOS:000226005200002

ISSN

1017-7825

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