The effects of pH on the characteristics of conversion of starch to methane in anaerobic digestion were investigated by using a laboratory-scale anaerobic fluidized bed reactor over the pH range of 5.8-7.0. Furthermore, a new operation method was proposed to treat wastewater containing starch effectively.
At pH 6.2, starch was decomposed well and methane was also formed well. The phenomenon showed methanogenesis in an attached growth system developed more tolerance for lower pH than in suspended growth type systems. After all, pH 6.2 was the optimum pH value for conversion of starch tomethane in our experiment.
From these results, it is proposed that the more effective anaerobic digestion is made possible by the operation at low pH (for example 6.2) which accelerates acidogenesis and doesn't inhibit methanogenesis in attached growth systems.