Anaerobic Digestion of Silk Industry Wastes.

In order to determine biogas potential of defatted silk
worm pupae waste, anaerobic batch digestion was carried
out in a 1-I bioreactor and, based on the results,
further experiments were conducted in a 20-I KVIC
(Khadi and Village Industries Commission) type digester
under semi-continuous feeding. The effect of seven load
ing rates was studied. The maximum yield of biogas
(0"53 m ~ kg-i volatile solids (VS) added) and methane
(0"38 m 3 kg- i VS added) was accomplished at a loading
rate of I kg total solids (TS) m -3 day -1. The methane
content was as high as 70%. The hydraulic retention time
(HR T) of 30-day digestion exhibited maximum yield of
biogas and methane. Ammonia-nitrogen related inhibition
of anaerobic digestion was observed. By appropriately
adjusting the carbon and nitrogen ratio with
carbonaceous substrate it may be possible to exploit the
commercial potential of defatted silk worm pupae waste.