Continuous co-digestion of cattle slurry with fruit and vegetable wastes and chicken manure

• Published in: Biomass & bioenergy 2002, Vol.22 (1), p.71-77
• Main Authors: Callaghan, F.J., Wase, D.A.J., Thayanithy, K., Forster, C.F.
• Format: Article
• Language: English
• Subjects: Anaerobic digestion; Cattle slurry; Chicken manure; Co-digestion; Fruit and vegetable wastes; Inhibition; Solid wastes
• ISSN: 0961-9534; 1873-2909
• DOI: 10.1016/S0961-9534(01)00057-5

Anaerobic digestion is a well established process for treating many types of organic waste, both solid and liquid. As such, the digestion of cattle slurries and of a range of agricultural wastes has been evaluated and has been successful. Previous batch studies have shown that based on volatile solids (VS) reduction, total methane production and methane yield, co-digestions of cattle slurry (CS) with fruit and vegetable wastes (FVW) and with chicken manure (CM) were among the more promising combinations. A continuously stirred tank reactor ( 18 litres ) was used as a mesophilic (35°C) anaerobic reactor to examine the effect of adding the FVW and CM to a system which was digesting CS. The retention time was kept at 21 days and the loading rate maintained in the range 3.19– 5.01 kg VS m −3 d −1 . Increasing the proportion of FVW from 20% to 50% improved the methane yield from 0.23 to 0.45 m 3 CH 4 kg −1 VS added, and caused the VS reduction to decrease slightly. Increasing the proportion of chicken manure in the feed caused a steady deterioration in both the criteria for judging digester performance. This appeared to be caused by ammonia inhibition.