Young Scientist
Mr. Tinku Casper D'Silva
Research Scholar
Centre for Rural Development and Technology, Indian Institute of Technology Delhi
INDIA
Anaerobic digestion has been globally recognized by the scientific communities in mitigating climate change by converting organic wastes into bioenergy. However, in the current scenario in rural India, the conventional feedstock used for biogas production is cattle dung. It is already established that 15 to 25 kg of cattle dung possesses a biogas productivity of 1 m3 of biogas (~50% of methane). In this study, various non-excreta type waste biomass was shortlisted based on physico-chemical characteristics suitable for anaerobic digestion and its availability in India. Through the multi-criteria decision-making approach of the weighted sum method, the best feedstock that can be adopted all over India is the dry fallen leaves. The preliminary batch scale study at controlled conditions of 3 %TS feeding rate and 37 ℃ temperature revealed that the 6 kg of dry fallen leaves could produce 1 m3 of biogas (~ 56 % methane content) within 35 days of operation. Later, to validate the laboratory scale results, the dry fallen leaves were treated in a semi-continuous reactor for 45 days during prewinter conditions (decreasing from 27 to 16 ℃). At the same feeding rate conditions, about 10 kg of dry fallen leaves produced 1 m3 of biogas (~52% methane content). The variation in the results was mainly due to the strong connection between the operating temperature and methane-producing bacterial activity. For every 1 ℃ of operating temperature, the volatile fatty acids production profile was hiked up while the alkalinity profile and biogas yield were decreased. However, the overall reactor operation was successfully stabilized during the operational period. Even though the proposed strategy shows significant output regarding localized bioenergy production, the study recommends more long-term studies of the dry fallen leaves-based biogas plant to be adaptable for rural households.