Co-digestion of rice straw and cow dung to supply cooking fuel and fertilizers in rural India: Impact on human health, resource flows and climate change

摘要

Anaerobic digestion of cow dung with new feedstock such as crop residues to increase the biogas potential is an option to help overcoming several issues faced by India. Anaerobic digestion provides biogas that can replace bio-mass cooking fuels and reduce indoor air pollution. It also provides digestate, a fertilizer that can contribute to compensate nutrient shortage on agricultural land. Moreover, it avoids the burning of rice straw in the fields which contributes to air pollution in India and climate change globally. Not only the technical and economical feasibility but also the environmental sustainability of such systems needs to be assessed. The potential effects of implementing community digesters co-digesting cow dung and rice straw on carbon and nutrients flows, human health, resource efficiency and climate change are analyzed by conducting a Substance Flow Analysis and a Life Cycle Assessment The implementation of the technology is considered at the level of the state of Chhat-tisgarh. Implementing this scenario reduces the dependency of the rural community to nitrogen and phosphorus from synthetic fertilizers only by 0.1 and 1.6%, respectively, but the dependency of farmers to potassium from synthetic fertilizers by 31%. The prospective scenario returns more organic carbon to agricultural land and thus has a potential positive effect on soil quality. The implementation of the prospective scenario can reduce the health impact of the local population by 48%, increase the resource efficiency of the system by 60% and lower the impart on climate change by 13%. This study highlights the large potential of anaerobic digestion to overcome the aforementioned issues faced by India. It demonstrates the need to couple local and global assessments and to conduct analyses at the substance level to assess the sustainability of such systems.