The Fate of Coliform Organisms in
Waste Stabilization Ponds
J. F. MALINA, JR., Assistant Professor
and
Y. A. YOUSEF, Research Assistant
Environmental Health Engineering
Department of Civil Engineering
The University of Texas
Austin, Texas
The biological oxidation of domestic and industrial waste waters in stabilization ponds has been and is extensively employed to treat organic wastes.
The algal-bacterial system present in stabilization ponds is effective in producing an effluent which has a relatively low concentration of unstable organic matter and which is essentially free of pathogenic organisms (disease-
producing organisms).
The major objective of the research endeavor reported herein is to
evaluate the effect of the algal systems on the fate of coliform organisms,
specifically the effect of the environment produced by a high rate of algal
metabolism and the antagonistic effect of this environment on coliform organisms. Laboratory-scale stabilization ponds, in which the environments
(temperature, light nutrients, and detention time) were controlled, were used
in these studies.
LITERATURE REVIEW
The coliform organisms have been extensively employed as indicators
of possible fecal contamination of water. The bactericidal effect of various
waste-water treatment processes on the coliform organisms has been reported
in the literature. The environment established in an oxidation pond is such
that a marked reduction in the coliform population has been reported (1,2,
3.4,5).
The results of extensive field studies (1) indicate that the mean, medial
and modal reduction in the number of coliform bacteria in an oxidation pond
were 83, 95, and 96 per cent, respectively, and that a reduction in the
waste-water load to the pond did not increase the destruction of coliform
organisms. During periods of prolific algal growth there was marked reduction in coliform bacteria; however, under anaerobic conditions, a greater
survival of coliform bacteria was observed (1).
A reduction in the coliform density based on MPN was observed more
than 50 per cent of the time in ponds studied in the Dakotas, but the reduction in bacterial numbers was not appreciably different despite the variation
in the algal concentration (5).
Experimental studies of the treatment of waste water in a pond show that
99.99 per cent of the coliform organisms present in the influent of each cell
of the pond were destroyed in the individual compartments (2). The complete destruction of Salmonella enteric bacteria in a stabilization pond was
reported along with results indicating a reduction in coliform organisms of
99 per cent (4).
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