Treatment of Wine
Distillery Wastes by Anaerobic Digestion
G. J. STANDER, Director
National Institute for Water Research
South African Council for Scientific and Industrial Research
Pretoria, South Africa
INTRODUCTION
Wine distillery waste or spent wine, is the residue left after ethyl alcohol or
brandy has been distilled from wine. It contain residual organic acids, soluble
proteins and carbohydrates as well as various inorganic compounds which are normal
constituents of grape juice.
Spent wine has in the past been dealt with by means of lagooning or irrigation
but in most cases serious nuisance has arisen and pollution of streams and water
courses has been common. Due to the noxious nature of this effluent, it has not
been possible to incorporate it with normal sewage treatment, such as is commonly
practiced with industrial effluents. The average "strength" (organic load) of
distillery wastes is some 60 times as high as that of domestic sewage and consequently the effluent from a distillery may easily constitute as high aload as that
from a town with a population of 75, 000. This concentrated waste would require
excessive dilution in order to render it amenable to aerobic breakdown.
Laboratory and pilot scale studies undertaken by the NIWR(1, 2) from 1948 to
date, indicated that anaerobic digestion might provide a practical method for
dealing with such wastes. These studies, however, also emphasized the many unknown factors which still existed both with regard to the biological processes and
metabolic pathways involved, as well as the technological and physical aspects of
practical operation of an anaerobic digestion system. Extensive investigations
into the fundamental aspects of anaerobic digestion have thus been undertaken by
a team of workers at the main Laboratories of the NIWR, since 1960. In parallel
thereto, a program of operational research with a full-scale treatment plant has
been undertaken by the Cape Regional Laboratory of the NIWR, which is situated
in the main wine producing area of the country. This paper describes the results
of the latter investigations.
SELECTION OF FULL-SCALE PLANT
The organisms responsible for anaerobic stabilization of organic matter require the presence of active cell material at optimum concentration and therefore particular care must be exercised to retain the suspended cell material at the
required levels. Whereas in conventional sewage sludge digestion, the organic
solids and aqueous phase of the feed contain the necessary nutrients and organisms
for maintaining cell synthesis and activity industrial effluents are usually poorly
balanced in these respects. For successful digestion of these effluents it is essential
to ensure intimate contact of the feed with an active biota. Moreover, if the
rate of sludge synthesis is less than that lost in the effluent, a treatment plant must
provide for efficient separation and return of active cell material from the mixed
liquor which is displaced by raw feed.    A recent review of anaerobic digestion
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