A thesis submitted in partial fulfilment of the requirements for the degree of Master of Engineering, School of Environment, Resources and Development

Thesis (M.Eng.) - Asian Institute of Technology, 1987

Acidogenesis, acetogenesis, methanogenesis and sulfate reduction are the important reactions in anaerobic condition. Thus, to investigate the knowledge of mechanism of anaerobic condition, the characteristics of these reactions and their relationships were examined from the experiment in this study. In semi-continuous condition, the sludge was acclimated with three types of substrate to enhance three groups of bacteria and the incubation of various substrate with the bacteria in these sludge was done in batch experiments . During incubation period, various parameters such as COD, TOA, sulfate, methane production, etc. were analyzed. The results of acetate as substrate showed its degradation was the contrast between semi-continuous condition and batch experiments. For sulfate reduction, it took place together with acidogenesis, acetogenesis and acetate oxidation, however sulfate reduction with acidogenesis and acetogenesis were ·preferable. The results also indicated that acetogenic bacteria for degrading butyrate and for degrading propionate were different groups. Sulfate-reducing bacteria, as same as acetogenic bacteria, in butyrate degrading species were different from propionate degrading species that can not degrade butyrate.