Significance of Decentralized Biomethanation Systems in the Framework of Municipal Solid Waste Treatment in India

Operational strategy of high rate anaerobic digester with mixed organic wastes: effect of co-digestion on biogas yield at full scale

The present research work is aimed at providing an economically feasible solution for the farmers to exploit the mixed organic wastes (MOW) as resources for the generation of biogas based electrical power and utilize the same for irrigation purpose to reduce the dependence on electricity board. A full scale biomethanation plant has been installed based on anaerobic gas lift reactor (AGR) technology to analyse, understand the operational parameters of anaerobic digestion and assess the performance of a high rate biomethanation plant by co-digesting the MOW such as poultry litter (PL), cattle manure (CM) and napier grass (NG) at ambient temperature. The biomethanation plant was incorporated with inline pre and post-processing unit assembly. The plant was fed with 1000 kg of MOW per day having 250 kg of total solids, about 178-200 kg of volatile solids and operated continuously for 52 weeks under ambient temperature. Electrical power generated (84.5-104 kWh/day) from biogas (65-80 m³/day) containing methane (40-48 m³/day) was used for operating the water pumps for agricultural purpose and the digestate (115-130 kg/day) was exploited as organic manure for growing crops in the same field. Napier grass was grown in the same land and other feedstocks were procured from the nearby area at the cost of $10-$15 per ton. Around 6 acres of land was being cultivated using the biogas based power generated from the MOW that was being used for growing vegetables and maize.

Evaluation of single and two stage anaerobic digestion of landfill leachate: Effect of pH and initial organic loading rate on volatile fatty acid (VFA) and biogas production

This work aims to evaluate the impact of pH and initial organic load (IOL) in terms of Chemical Oxygen Demand (COD) of landfill leachate for the production of value added products during single and two stage anaerobic digestion (AD). It was observed that at an optimal IOL of 48 g/L, acetic acid was dominant at pH 5.5 whereas it was butyric acid at pH of 5.5-6.0 and 10-11. The yield of Volatile Fatty Acids (VFA) was dependent on IOL and it was in the range of 0.26 to 0.36 g VFA/(g COD removed). Methane was also harvested during single and two stage AD and found that it was varying in the range of 0.21-0.34 L CH₄/(g COD removed) and 0.2-0.32 L CH₄/(g COD removed) respectively. An overall increase of 21% COD removal was noticed in two stage AD in comparison to single stage.