2^nd World Bioenergy Congress and Expo

This paper evaluates the effect of additional substrate on the methanogenic activity of two different organic solid wastes such as tannery limed fleshing (TFL) and, fruits and vegetables (FVW) wastes, co-digested with common effluent treatment plant sludge for biomethane production. Each of the minced solid wastes were mixed with nutrient-seeded inoculum in ratio of 3:1, with various sodium acetate (NaOAc) concentrations and loaded into borosilicate glass serum bottles of 150 ml capacity. The experiment was carried out under a mesophilic (35± 2°C) temperature for a period of 30 days in hermetically sealed batch anaerobic reactors. The methanogenic activity increased as the cumulative gas produced increased along with varying NaOAc concentrations that ranged from 8.91-17.88 Nm.mL CH4/gVSS.d-1 for TFL waste and 29.84-121.09 Nm. mL CH4/gVSS.d-1 for FVW respectively. The experiment without additional substrate-NaOAc (control) showed that the TFL control had the highest production (161.05 Nm.mL.d-1) compared to the NaOAc-added-substrates. However, at 0.3g NaOAc conc., the FVW had the highest gas production (432.10 Nm. mL. d-1) with an activity of 121.09 Nm. mL CH4/gVSS.d-1 than the remaining reactors. While, higher concentration of 0.4g NaOAc in FVW resulted in a decreased methanogenic activity yield. Therefore, the study showed that the methanogens activity involved in the degradation of TFL waste for gas production was found to be lower than FVW. Thus, the study concluded the need for two stage hdyrolyzer followed by methanizer, to feed VFA (acetate) alone in the methanizer and to produce enhanced biogas yield than single stage digester.