Effect of pre-treatment on mesophilic anaerobic co-digestion of fruit, food and vegetable waste

Pre-treatment of fruit, food and vegetable waste materials could enhance the biogas generation and waste stabilization in a shorter time. Effect of alkaline, hydrothermal, thermal and ultrasonication pre-treatment of fruit, food and vegetable waste (FFVW) on the anaerobic co-digestion (ACD) was assessed in terms of total solid (TS), volatile solid (VS) reduction and biogas/methane production. The mesophilic anaerobic co-digestion of pre-treated FFVW with cow dung was performed in a laboratory scale 1L batch digester for 30 days at 40 +/- 2 degrees C temperature. Performance of ultrasonication process is found more economical and efficient pre-treatment over other pre-treatment processes such as thermal, alkaline and hydrothermal processes. Obtained results show that ultrasonication pre-treatment process enhances the biogas and biomethane production by 29.4% and 18.4%, respectively. During ultrasonication pre-treatment, 16.89% TS and 19.44% VS removal are noted. While 106.81 ml biogas/gVS and 29.92 ml CH4/gVS are generated during ACD of ultrasonicated FFVW. In addition, considerable enhancement in biogas production was noted with alkaline pre-treatment but it is least economical. Economic analysis shows that the cost for the production of biogas through anaerobic co-digestion from untreated, ultrasonication, alkaline, hydrothermal and thermal pre-treated FFVW are 2.45, 3.12, 19.33, 5.52 and 22.72 USDs/ton FFVW, respectively. Energy study also indicates the lesser energy consumption and higher biogas production in case of ultrasonication pre-treatment. [GRAPHICS] .