Anaerobic digestion of seaweed for biogas: A kinetic evaluation

Abstract

Abstract A kinetic study of biogas production in batch digesters by anaerobic digestion of seaweed, Sargassum tenerrimum, with a mixed bacterial culture consisting of methanogenic bacteria and an algin‐degrading bacterial strain was carried out at different concentrations of dry total solids. Specific rate constants of biogas production during the lag, exponential and monomolecular ( stationary ) phases of bacterial growth were determined. About half the total volume of biogas was generated during the exponential phase irrespective of the concentration of seaweed in the digesters. The specific rates of substrate destruction and biogas generation in the stationary phase decreased with increasing substrate concentration. The yield of biogas per gram dry total solids of seaweed was about the same at all concentrations, but with a marked decline at 12% ( w/v ) total solids. The maximum destruction of volatile solids effected was about 63% over a period of 72 days.