KINETICS OF ACETOGENESIS AND METHANOGENESIS IN ANAEROBIC REACTIONS UNDER TOXIC CONDITIONS

A method for assessing the impact of toxic organic compounds on the ki netics of acetogenic reactions is presented. The test program involved dosing ethanol-enriched anaerobic cultures with an isomeric series of chlorophenols and chloroanilines. The effect on the acetogenic conver sion of ethanol was monitored by measuring the residual ethanol and ac etate in batch serum bottle tests. followed by mathematical analysis t o determine coefficients of kinetic and inhibition models. A feature o f the presently-described research program was the use of the specific biomass responsible for acetogenesis and methanogenesis in kinetic mo dels rather than using the total biomass. The distribution of biomass in the ethanol-enriched test culture was 25.4% hydrogenotrophic methan ogens. 41.1% acetoclastic methanogens, and 33.5% ethanol degrading ace togens. The effects of the chloroanilines and chlorophenols on both ac etogenesis and methanogenesis appear to be best described as mixed inh ibition, and the effects were not clearly related to the position of f unctional groups. In all cases, the test chemicals were more toxic to the acetoclastic methanogenesis reactions than to the ethanol-degradin g acetogenic reactions.