Production of methane from green pea shells in floating dome digesters

The suitability of green pea shells for biogas production was evaluated in floating dome digesters. The stepwise replacement of cow dung with green pea shells in the digesters enhanced the stability of the anaerobic digestion system. Green pea shells formed a thick scum on the top and thereby blocked the ports of the digesters, but ensilaging shells for 6 months helped to overcome this problem. Ensilaging of green pea shells for 15 days only caused the separation of fibrous constituents from the soluble and suspended solids. The resultant liquid yielded 0.62 m(3)/kg VS biogas and reduced the hydraulic retention time from 30 to 10 days at a loading rate of 8% (TS). (C) 1997 Elsevier Science Ltd.