ACETATE DEGRADATION AT 70-DEGREES-C IN UPFLOW ANAEROBIC SLUDGE BLANKET REACTORS AND TEMPERATURE RESPONSE OF GRANULES GROWN AT 70-DEGREES-C

Anaerobic acetate degradation at 70-degrees-C and at 55-degrees-C (as a reference) was studied by running laboratory upflow anaerobic sludge blanket (UASB) reactors inoculated with mesophilic granular sludge. I n UASB reactors fed with acetate-containing media (3 g of chemical oxy gen demand [COD] per liter, corresponding to 47 mM acetate) approximat ely 50 days was needed at 70-degrees-C and less than 15 days was neede d at 55-degrees-C to achieve an effluent COD of 500 to 700 mg/liter. I n the UASB reactors at both 70 and 55-degrees-C up to 90% of the COD w as removed. Batch assays showed that sludges from two 70-degrees-C UAS B reactors, one run at a low effluent acetate concentration and the ot her run at a high effluent acetate concentration, exhibited slightly d ifferent responses to temperatures in the range from 37 to 70-degrees- C. Both 70-degrees-C sludges, as well as the 55-degrees-C sludge, prod uced methane at temperatures of 37 to 73-degrees-C. The 55-degrees-C s ludge exhibited shorter lag phases than the 70-degrees-C sludges and h igher specific methane production rates between 37 and 65-degrees-C.