Decentralized application of anaerobic digesters in small poultry farms: Performance analysis of high rate self mixed anaerobic digester and conventional fixed dome anaerobic digester

Biomethanation of poultry litter was studied in conventional fixed dome anaerobic digester (CFDAD) and high rate self mixed anaerobic digester (SMAD) for possible decentralized application in poultry farms generating litter in the range of 500 kg/day. The performance of CFDAD and SMAD was compared. The study revealed that optimized hydraulic residence time (HRT), volatile solids (VS) loading rate, VS reduction, methane yield was 24 days, 4.0 kg VS/m3/day, 64%, 0.15 m3/(kg VS fed) and 40 days, 2.15 kg/m3/day, 42%, 0.083 m3/(kg VS fed) for SMAD and CFDAD, respectively. Better results with SMAD could be attributed to specific design features and intermittent mixing of the digester contents due to self-mixing mechanism. Preliminary cost estimates revealed that installation of SMAD would be remunerative for the farmer in terms of biogas and bio-manure.