Selective use of microorganisms in anaerobic treatment processes by application of immobilization

The cell immobilization technique using polyvinyl alcohol and boric acid was applied to the anaerobic process. Immobilized cells of Clostridium butyricum were used to enhance butyrate production in a continuous reactor under a mixed culture condition. There was a tendency that more butyrate was produced in the immobilized cell system than in the non-immobilized cell system at (1) a dilution rate lower than 0.14 h −1 at pH 6 and (2) a pH higher than 5.5 with a dilution rate of 0.036 h −1. The enrichment culture of the propionate-utilizing consortium was immobilized and used in a mixed culture condition with suspended biomass which could convert glucose to methane. Batch experiments using this mixture of biomass and those using non-immobilized cells alone were carried out. Methane production from acetate, propionate or glucose proceeded much more rapidly, and accumulation of propionate during glucose degradation was much shorter when the immobilized cells were used.