Thermophilic Degradation of Butyrate, Propionate and Acetate in Granular Sludge

Abstract

Anaerobic degradation of butyrate and propionate is dependent on interspecies hydrogen transfer. From thermodynamic calculations it is obvious that propionate requires the lower hydrogen concentration and the degradation of propionate is, therefore, usually the rate limiting step, especially in high rate anaerobic treatment systems (2). Studies on product inhibition of butyrate by acetate and hydrogen have shown that thermophil butyrate degradation depend on both hydrogen and acetate removal (1). The concentration of propionate might also effect the degradation of butyrate. The purpose of this study was to determine specific methane production rates from butyrate, propionate, and acetate and examine the effect of propionate on the butyrate consumption rate in granular sludge from a UASB-reactor with a relatively high concentration of propionate not degraded and, therefore, found in the effluent from the reactor.