The Effect of Whey Upon the Operation of
An Activated-Sludge Plant
D. P. Backmeyer
Superintendent of Sewage Treatment Plant
Marion, Indiana
It is the purpose of this paper to bring to the attention of those
primarily interested in both the disposal and utilization of dairy byproducts the specific problem of treating sewage containing cheese
whey.
The discussion will necessarily be limited to the experiences encountered at the Marion, Indiana, sewage-treatment plant. This plant is
modern in design, and employs the activated-sludge treatment process
for secondary purification of the sewage and industrial wastes from the
city of Marion. Under normal operating conditions, the plant has not
been excessively loaded, and as a result a consistently satisfactory effluent
has been produced since the plant was put in operation about seven
years ago.
The problems involved in the treatment of sewage containing
cheese whey can be divided into two classes: namely (1) overload conditions resulting from "batch" doses of whey dumped to the sewer at
infrequent intervals, and (2) the continuous daily dumping of whey
into the sewer system. The problems will be discussed in the order
mentioned.
A typical example of a flare-up resulting from "batch" waste dumping of whey occurred in February, 1946. As routine daily tests were
made for dissolved oxygen at the effluent weirs of the aeration tanks on
the morning of the 19th, it was noted that the D.O. concentration was
dangerously low. A check of flow conditions and air volume being supplied to the aeration tanks showed these factors to be apparently normal.
After some further observations were made, several conditions were
noted that indicated a highly concentrated industrial waste had reached
the secondary-treatment tanks. The suspicion that the waste might be
cheese whey was verified after making several telephone calls to local
plants processing dairy products. One of the industries had dumped
about 25,000 pounds of whey into the city sewer. At first consideration,
this amount of whey may seem like an insignificant dribble of industrial
waste which any treatment plant might take in its normal stride. However, this is not the case. Just consider what happened to the activated-
sludge plant, and why it happened.
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