Formation of an acetate-type climax community and its change subjected to COD/SO4 ratio in an acidogenic sulfate-reducing reactor

In order to investigate the formation of an acetate-type climax community and its change subjected to COD/SO4 ratio in sulfate-reduction unit of a two-phase anaerobic bio-treatment process, a lab-scale study was performed in an acidogenic sulfate-reducing reactor with molasses wastewater as sole organic carbon source and sodium sulfate as electron acceptor. The changes of terminal liquid products and microbial populations from low to high COD/SO4 ratios were discussed, and the internal balance and feedback adjustment mechanism of the climax communities were analyzed as well. The experimental results showed that acetate accumulation resulted in the formation of acetic acid type metabolism. Acetate-type climax community developed from the ecological succession aroused by COD/SO4 ratio. Acetic acid type metabolism and acetate-type climax community were of typical characteristics of the acidogenic sulfate-reducing ecosystem. In addition, the change of COD/SO4 ratio caused the ecological succession from the stable climax community at moderate and high COD/SO4 ratios to sub-stable climax community at low COD/SO4 ratio, respectively.