Some Effects of Copper on the
Activated Sludge Process
LEON S. DIRECTO, Sanitary Engineer
Rackoff Associates
Columbus,   Ohio
and
EDWARD Q. MOULTON, Assistant Dean
Graduate School
The Ohio State University
Columbus, Ohio
Perhaps one of the least understood and at the same time extremely important areas of the waste treatment is that of toxicity. As an example of the
lack of a fundamental understanding in this general subject one only has to
observe the tremendous variations of "allowable levels" of various toxic substances in the local sewer codes throughout the country. However, to anyone
familiar with the data on this subject available in the literature, this lack of
uniformity is not surprising.
While there had been a number of investigations accomplished dealing
with some facets of the problem, the results reported are not only meager but
also conflicting in nature. There are also large areas where no information is
available. For instance, a survey of available literature reveals no specific
information relating to intereffects of metallic ions or even the influence of
operational variables, viz., organic loading and aeration tank suspended solids concentration on the toxic action of these ions. Investigations that had
been undertaken so far and reported in the literature covered only the singular
effects of selected metallic ions. Hence, much more apparently remains to
be done in attempting to arrive at a better understanding of the probable
mechanisms or interactions that may occur. In the previous work of the authors (1) an attempt was made to evaluate statistically the singular and intereffects of four metallic ions, copper, chromium, nickel, and cyanide commonly found in metal plating wastes on the activated sludge process.
The research reported in this paper, however, was directed toward the
evaluation of the response of a biological treatment process, the activated
sludge process, to shock loadings of copper, under varying organic loadings
(influent sewage concentration) and to suspended solids concentrations.
A careful review of past researches on the subject of toxicity indicated in
many cases the lack of adequate controls. In conducting a research program
with any "biological system" there are inherently present a whole host of
variables that have a direct influence on the process. The real challenge to
the researchers is to design an experiment in such a way as to select and emphasize those variables that are of primary importance and to minimize the
effects of the other variables that are not of direct importance.
TEST UNITS
The experimental units consisted of six identically-designed activated
sludge pilot plants as shown in Figure 1. Each of these units is composed of
four components; synthetic sewage container, aeration tank, secondary settling   tank,   composite  sampler  and   other   appurtenant  apparatus  such  as
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