Converting brewery waste to ethanol.
Sidor, L.L. and Knight, P.D.
In 1976 the Olympia brewery's Turnwater plant was committed to participation in a municipal scheme for effluent treatment. The sewer loading potential of effluent discharged was estimated at 3.74 bbl flow/barrel, 2.44 lb BOD/barrel packaged and 0.94 lb SS/barrel packaged which would have represented an increase of 1000% in the annual cost of waste treatment. As a preliminary step the brewery carried out process changes to limit plant flow to 2 m gallons/day and reduced the effluent load of last wort from the lauter tuns, wort from the hop back and waste from the cooling delivery systems, (savings tabulated). A pretreatment scheme was devised in which streams containing waste beer and fermentable material would be collected, filtered, concentrated, combined with waste yeast and fermented. The resultant 'beer' would then be distilled and the recovered alcohol sold to defray operating costs. After preliminary pilot plant trials to establish feasibility and optimum conditions a Waste Products Recovery (WPR) plant was constructed in 1981 costing $7 m. Details of construction and operation are given and performance data covering the last few years is reviewed. Participation in the municipal treatment scheme is now at the rate of 3.29 bbl flow, 0.92 lb BOD and 0.16 lb SS/ barrel packaged representing reductions of 12.0% flow, 62.3% BOD and 82.3% SS. A profit of 3.8 cents/lb BOD processed has been achieved in contrast to a muncipal charge of 14.7 cents/lb. The WPR requires 2.1 cents/lb SS removed against a municipal charge of 10.5 cents/lb.
Keywords : brewery effluent ethanol fermentation plant recovery system waste wort