The Anaerobic Filter for the Treatment of
Brewery Press Liquor Waste
CHARLES R. LOVAN, Graduate Student
EDWARD G. FOREE, Assistant Professor
Civil Engineering Department
University of Kentucky
Lexington, Kentucky
INTRODUCTION
The anaerobic filter consists of a bed of media suitably sealed from the
atmosphere to maintain an oxygen-free environment. The filter media are similar to
those used in aerobic trickling filters. The waste to be treated is distributed across the
bottom of the filter and flows upward so that the filter is completely submerged.
Anaerobic microorganisms become attached to the filter media and trapped in the
void spaces. The waste comes in contact with a large biological mass as it passes
through the filter and is stabilized by the metabolic activity of these microorganisms.
Methane and carbon dioxide gases and a relatively small quantity of biological cell
material are the primary end products.
Anaerobic processes have generally been limited to high-strength organic wastes
because the slow-growing methane forming microorganisms require long detention
times and thus large digester volumes for satisfactory stabilization of lower strength
wastes. In anaerobic contact processes, which require solids settling and recycle to
maintain a high concentration of active biological solids, soluble wastes present a
problem since biological solids usually remain dispersed or lightly flocculated and
may pass out with the effluent. With the anaerobic filter the filter media trap and
retain the biological solids, the long solids retention times are obtainable, and the
need for solids separation and recycle is eliminated. Thus the anaerobic filter is
ideally suited for the treatment of a soluble waste (1).
Brewery press liquor waste is characterized by a very high concentration of
dissolved organics, a moderately low concentration of suspended organics which can
very readily be removed by sedimentation, and high temperature, usually 125—130
F. The results of previous studies using synthetic wastes (1) and a food processing
waste (7) indicate that the above characteristics should make this waste highly
susceptible to successful treatment by the anaerobic filter.
ORIGIN OF BREWERY PRESS LIQUOR WASTE
The origin of "Brewery Press Liquor Waste" can be seen from the flow diagram
of a typical brewery operation (Figure 1). The making of beer is basically the
conversion of starch to sugar so that the yeast can ferment the sugars to form alcohol
and carbon dioxide. The process proceeds down through the lauter tub, through
fermentation, and on to the bottling of the beer. From the lauter tub and hop
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