Research in the Disposal of
Distillery Wastes
E. C. Pattee
Consulting Chemical Engineer
Cincinnati, Ohio
Recent research on distillery slop has been concerned mostly with
the utilization and upgrading of recovered materials, but sufficient work
has been done in connection with the elimination of stream pollution
to justify a summation and re-examination at this time of all disposal
processes. Wastes from both whiskey and brandy distilleries will be discussed because these two slops create similar problems even though their
raw materials differ. Both slops are the residues from distillation of
alcohol from fermented solutions.
Processes Involved
Both types of slops are dilute solutions (1 to 10 percent solids) containing insoluble and soluble solids in the approximate ratio of 60 to 40.
The differences in compositions of the insoluble and soluble solids have
led to different uses and values for the recovered materials. In view
of some of the newer uses for these materials, especially whiskey-slop
solids, it may be desirable to review briefly some of the methods employed
for separating solids from the liquid slops.
All the methods for recovering slops are based upon converting
them into dry products which can be safely stored and shipped. This
has been accomplished by separating the solids from the liquid in order
to obtain the most economic evaporation of the water. The method of
separating the solids is usually determined by an over-all cost balance
on the processing. Some of the separating or clarifying methods for
grain-distillery slop and their separation efficiencies are given in Table 1
in order to indicate the range of clarification permissible on a commercial
scale. This general degree of clarification has been obtained on various
types of distillery slops.
The information in Table 1 does not tell all the story because
evaporation is the biggest cost-item in slop recovery. A decrease in
percentage of suspended solids helps to reduce the cost of evaporation.
Sometimes the decrease in evaporation costs may be offset by higher
costs of clarification; therefore over-all engineering and economic bal-
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