Effect of control of pH in anaerobic digestion of organic fraction of municipal solid waste

Anaerobic digestion often encounters the problem of higher population of the acid-forming bacteria relative to the slower growing methanogenic bacteria which inhibits the methanogenic process leading to problems such as low gas yield and process instability. In this study, anaerobic digestion of organic fraction of municipal solid waste has been carried out in two identical model laboratory-scale single stage anaerobic digesters simultaneously; one without the control of pH and other with the control of pH, with same substrate keeping all other conditions identical. Results indicated that the hydraulic retention time of AD reaction could be reduced by at least seven days and the overall efficiency of gas production of the digester could be increased by more than 21.95% (at 50 days time) by the control of pH in the digester.