Effects of acetate, propionate, and butyrate on the thermophilic anaerobic degradation of propionate by methanogenic sludge and defined cultures.

Accumulation of long chain fatty acids onto anaerobic sludge under steady state and shock loading conditions: effect on acetogenic and methanogenic activity.

Accumulation of substrate onto the biomass was quantified under steady-state and shock conditions in a fixed bed reactor fed with an oleic acid-based synthetic effluent. The accumulation of substrate onto the sludge was more dependent on oleic acid concentration than on oleic acid loading rate and decreased the acetogenic, acetoclastic and hydrogenophilic activity. However, even when the methan...

Relative importance of trophic group concentrations during anaerobic degradation of volatile fatty acids.

Although obligate syntrophic reactions cannot proceed without hydrogenotrophs, it has been unclear from the literature whether potential improvements are achievable with higher concentrations of hydrogenotrophs. In this study, the relative importance of formate-/H(2)-utilizing and acetate-utilizing trophic groups in the anaerobic degradation of butyrate and propionate was assessed by adding var...

Formation of Fatty Acid-degrading, anaerobic granules by defined species.

An endospore-forming, butyrate-degrading bacterium (strain BH) was grown on butyrate in monoxenic coculture with a methanogen. The culture formed dense aggregates when Methanobacterium formicicum was the methanogenic partner, but the culture was turbid when Methanospirillum hungatei was the partner. In contrast, a propionate-degrading, lemon-shaped bacterium (strain PT) did not form aggregates ...

Inhibition of Thermophilic Anaerobic Digestion of Waste Food by Long Chain Fatty Acids and Propionate

Mineralization of LCFA associated with anaerobic sludge: Kinetics, enhancement of methanogenic activity, and effect of VFA.

Long-chain fatty acids (LCFA) associated with anaerobic sludge by mechanisms of precipitation, adsorption, or entrapment can be biodegraded to methane. The mineralization kinetics of biomass-associated LCFA were established according to an inhibition model based on Haldane's enzymatic inhibition kinetics. A value around 1,000 mg COD-LCFA..g VSS(-1) was obtained for the optimal specific LCFA con...