Effect of Predigestion Process Modifications on VFA Enhancement and Overall Biogas Conversion from Kitchen Solid Waste

Abstract

The bioprocessing methodology of predigester has been modified to optimize the kitchen solid waste processing for enhanced biogas production. The batch and semi-batch study of bioprocess modification in the predigester by adding <i>Candida sp</i>. to acetogenic predigester culture with controlled aeration (micro-aerobic) has shown the enhancement in volatile fatty acid (VFA) in predigestion. The study of pilot plant which was operated with 24 - 30 days of hydraulic retention time (HRT) with average rate of feeding was 67-82 kg-wet/day. The experiment resulted with average volatile fatty acid (VFA) concentration of 25.41 g/l enhanced from 18.04 g/l in predigestion and ultimately average biogas production increased to 16.23 m³/day from 6.76 m³/day. The efficiency of biogas production per unit feed processed was enhanced from 0.099 m³/kg-wet to 0.2 m³/kg-wet. The present study of waste to energy technology offers a promising decentralized alternative for organic solids/ food waste utilization for enhanced biogas production.