Impact of Leachate Circulation on Co-Digestion of Rice Straw and Market Waste for Biogas Production

Abstract

Laboratory-scale digesters were operated to study the effect of leachate circulation on biogas production. Two reactors (20L) were performed using market waste and rice straw (< imm particle size) in 1:3 ratio. One reactor was operated with leachate circulation in once a day and other one was performed in twice a day (12 hrs interval). After filling the reactors with required total solid level (20%), the digested material of a biogas digester (operated by market waste alone) were added to reactors in equal quantity as inoculums and reactors were sealed. Biogas production, methane content, temperature and pressure were measured in daily and pH, chemical oxygen demand (COD) in leachate samples were regularly monitored in once a week. After 100 days of anaerobic digestion, it was observed that the gas production, pH, COD in reactor 1 (leachate circulation in twice a day) was better than the reactor 2 (leachate circulation in once a day). The initial measurable gas production was observed during 4-5 days after filling the reactors. After ~ 40 days, the maximum gas amount was produced and it was gradually decreased. The comparatively higher gas production was noted in reactor 1. Total gas production in two reactors were 40714 and 36325 cm3/kg of dry matter, respectively. When the leachate circulate frequently, COD were reduced due to consuming the volatile fatty acid by methanogenesis. Based on this study it can be concluded the leachate circulation influence the rate of biogas production while consuming the COD in leachate.