Anaerobic composting of crab-picking wastes for byproduct recovery

The objective of this project was to determine the feasibility of using two-stage anaerobic composting to stabilize crab-picking wastes, produce a residue amenable to byproduct recovery, and to compare flooded versus percolating operation of the leachbed. Crabpicking waste (CPW) was treated using duplicate, two-phase reactor systems consisting of 14-l leachbed reactors and 5-l hybrid sludge-bed filter reactors. Biochemical methane potential of the CPW, solids reduction, methane production and leachate pH, alkalinity, conductivity, volatile organic acids (run 4 only), and chemical oxygen demand were monitored. Methane yields approached or attained the BMP value (0.31 m3 kg−1 VS−1), except for run 2, which was stopped at 20 days due to mechanical problems. Mean solids reduction was 80% (SD = 2). Residues were not odoriferous, had a low bulk density (85 g l−1) and were stored at ambient temperature with no vector attraction potential. There was no difference in methane yield or VS conversion between percolating and flooded operation of the leachbeds.