68    INVESTIGATION OF BACTERIA PRODUCING HIGH FECAL
COLIFORM MPNs IN AN INDUSTRIAL WASTEWATER
TREATMENT FACILITY EFFLUENT
E.M. Davis, Professor, Environmental Science
E.J. Kleintop, Graduate Research Assistant
J.J. Mathewson, Assistant Professor
Center for Infectious Diseases
T.D. Downs, Professor, Biometry
The University of Texas
School of Public Health,
Houston, Texas 77225
INTRODUCTION
In mid-1990 the effluent of a 60 mgd regional industrial collection and treatment plant was found to
contain high concentrations of fecal coliforms. This plant was the first in the U.S. to mix industrial
waste streams from different industries in a single biological joint wastewater treatment process. A
modified activated sludge process is used with small amounts of pH control and nutrient addition.
Nine industrial waste streams and one small domestic stream are treated in the plant. A bacteriological
survey of the largest volume stream, a pulp and paper mill, and three locations within the plant was
conducted from May through October, 1990.' A second survey of nine separate incoming waste
streams and the plant outfall was conducted from August, 1991 through February, 1992.2 Fecal
coliform bacteria, fecal streptococci and enterococci were quantified and fecal coliforms characterized by biochemical testing to evaluate the source of those bacteria. Only three incoming waste
streams contained very low volumes of domestic wastewater, and all three had been thoroughly
disinfected prior to entry in the main plant.
MATERIALS AND METHODS
Fecal coliforms were analyzed by the membrane filter (mFC agar) and the MPN method using A-l
broth (Standard Methods3). Colonies were streaked on nutrient and MacConkey agar and tested for
oxidase reaction. Oxidase negative colonies were transferred to EC broth, incubated at 44.5° for 24
hours and positive cultures (gas production) from those were analyzed by the API-20E biochemical
tests (Analytab Products, Plainview, N.Y.) for identification to genus. Fecal streptococci and enterococci were also enumerated by the membrane filter methods using M Enterococcus agar for F. strep,
and mE agar and EIA media for enterococci. All samples were 24-hr refrigerated composites.
RESULTS AND DISCUSSION
The single domestic wastewater stream entering the plant was acid treated to a pH of less than 2
before lime neutralization. No bacteria were found in that stream.1 Stream 701, the paper mill waste
stream, contained process and some stormwater. Manville1 found predominantly Klebsiella in that
water while the second investigation showed some E. coli present.2 Those E. coli may have been
misidentified and may have been E. hermanii, et al.3,4 Stream 401 was a petroleum company process
waste with some stormwater. Klebsiella and Enterobacter were the most frequently identified fecal
coliforms. Stream 601 was a water treatment chemical sludge from the petroleum company producing
Stream 401 and contained generally extremely low numbers. Stream 901 was a treated refinery waste
effluent with a small amount of chlorinated sanitary waste. Klebsiella constituted 73-92% of the fecal
coliform count while Escherichia ranged from 8 to 27%. Stream 501 contained process wastewater
activated sludge from secondary clarifiers from a petrochemical plant. Quite often fecal streptococci
counts exceeded those for fecal coliforms. Stream 1001 came from a bulk chemical terminal washing
48th Purdue Industrial Waste Conference Proceedings, 1993 Lewis Publishers, Chelsea, Michigan 48118. Printed in
U.S.A.
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