Effect of Operational Parameters on Biogas Production using Tomato Waste as Substrate and Cow Dung as Inoculating Medium

A balanced and self-inoculated system that could maintain the optimal acidogenic-methanogenic microbial ratio for the consistent production of biogas was developed using cow dung as mixed microbial culture. This was attained by maintaining the system in mesophilic phase (28-34 0C) and neutral pH in a 50 L scale digester for 10 days during which the reactor was treated as the batch digester and analyzed for biogas production. A cumulative gas production of 27.5 L was observed and the gas attained flammability form the 4th day of experiment. The digester was next fed with tomato wastes in a semi continuous manner and observed for gas production. Parameters influencing the gas production such as OLR (organic loading rate), pH, and hydraulic retention time (HRT) were optimized during the process. The average gas production was optimum for HRT of 24 days and moderate for 20 days but the digester turned acidic at HRT of 16 days with volatile solid (VS) concentration 8 % W/V and OLR of 5 Kg VS/m3 day.