Anaerobic Treatment of Distillery
Wastes (Pilot-Plant Studies)
Alex B. Davidson
Engineer, Schenley Distillers, Inc.
Cincinnati, Ohio
James F. Banks
Chemist, Geo. T. Stagg Company
Frankfort, Kentucky
In the fall of 1947 a graduate student in sanitary engineering at
Purdue University, Mr. James C. Hargleroad, was reported to be obtaining excellent results on the anaerobic digestion of strawboard wastes.
As the strawboard wastes appeared similar to distillery wastes, it was
decided to investigate the possibility of applying the same process of
treatment to distillery wastes. A trip was made to Purdue to discuss
with Professor Bloodgood and Mr. Hargleroad the procedures used
in their experiments.
General Description of the Distillery Process and Wastes
The term "distillery wastes" as used in this paper does not mean the
spent mash (also known as slop or stillage), but refers to the remaining
wastes from the distillery and dry house after the spent-mash has been
recovered. Most modern distilleries with more than 1,000 bushels per
day are equipped with dry houses which effectively evaporate and dry
the spent-mash from the stills to produce a by-product—cattle feed.
Since a dry house is a very costly installation, it is generally not practicable for the very small distilleries to have such equipment, and their
common method of spent-mash disposal is by feeding it in the wet form
to cattle or selling it to farmers.
The dry house, in brief, is a series of operations which progressively
reduce the water content of the spent-mash. The spent-mash from the
beer still is passed over several sets of screens which reduce the water
content to about 83% (the original spent-mash from the beer still
contains about 96% of water). The thick spent-mash is then put
through a press to reduce the water content to about 67%. The pressed
material then passes through rotary dryers to emerge as a dried grain
containing about 8% moisture.
The thin spent-mash, which passes through the screens, and includes
that from the presses, is evaporated in multiple-effect evaporators which
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