Aerobic Treatment of Wastes High
in B.O.D. Concentration
HARRY W.   GEHM
Technical Advisor
National Council for Stream Improvement
(of the Pulp, Paper and Paperboard Industries, Inc.)
New York, New York
Treatment of small volumes of industrial wastes with a high B.O.D.
concentration has long been a plaguing problem. Evaporation and combustion are in some instances applicable, but not universally so for many
reasons. Anaerobic digestion has been successfully applied for some
wastes but concentrations which can be handled are limited and operation is critical. Dilution with wastes of low concentration or cooling
water followed by common types of aerobic treatment is not uncommon.
In many situations, however, this expedient is impractical since the
structures required to treat the diluted waste become extremely large.
Fermentation of such wastes to produce solvents or yeasts has been
successfully employed but this procedure is decidedly limited in application despite the economic advantage it provides, particularly where small
quantities of waste are involved.
During the last few years attention has been given to the possibility
of treating such wastes by adaption of the activated sludge process,
employing long periods of aeration and higher seed concentrations as
well as supplementation of waste with nutrient salts. In some instances
dispersed rather than flocculent growths occur in the liquor under treatment and are returned to the raw waste as seed. Oxygen has also been
applied rather than air (1). Foam phase oxidation has also been tried
(2). It is the purpose of this paper to review briefly progress in the
development of these processes and to evaluate as far as possible their
possible application.
Although in effect, yeast production from various substrates has
been accomplished by substantially the same technique, it was comparatively recently that long-period aeration techniques were applied to
industrial waste purification. Heukelekian experimented with dispersed
growth treatment of various carbohydrate wastes including antibiotic
spent broths, (3), (4) and rice water (5). Table I is a brief summary
of results he observed when employing a 24 hour aeration period and
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