ANAEROBIC-DIGESTION OF SILK INDUSTRY WASTES

In order to determine biogas potential of defatted silk worm pupae was te, anaerobic batch digestion was carried out in a 1-1 bioreactor and, based on the results, further experiments were conducted in a 20-l KV IC (Khadi and Village Industries Commission) type digester under semi- continuous feeding. The effect of seven loading rates was studied. The maximum yield of biogas (0.53 m3 kg-1 volatile solids (VS) added) and methane (0.38 m3 kg-1 VS added) was accomplished at a loading rate of 1 kg total solids (TS) m-3 day-1. The methane content was as high as 70%. The hydraulic retention time (HRT) of 30-day digestion exhibited maximum yield of biogas and methane. Ammonia-nitrogen related inhibiti on of anaerobic digestion was observed. By appropriately adjusting the carbon and nitrogen ratio with carbonaceous substrate it may be possi ble to exploit the commercial potential of defatted silk worm pupae wa ste.