Anaerobic digestion of palm oil mill effluent and its utilization as fertilizer for environmental protection

Biodegradation of palm oil mill effluent (POME) under anaerobic conditions to environmentally acceptable products was carried out. This method of digestion was chosen in preference to the aerobic mode, among other factors, efficiency of COD and BOD removal and relevance of the operation to the needs of local communities. Studies were carried out in three experimental set-ups:- (i) a single stage anaerobic ponding system (ii) a single stage anaerobic tank digester with a certain degree of mixing (iii) recycled spent POME sludge in a single stage anaerobic tank. Operational variables such as optimum pH, the COD/BOD removal efficiencies and the overall usefulness of the digester modes to local communities and farmers are discussed. Results obtained show that the efficiencies obtained from the 3 set-ups are 96.91%, 96.50% and 94.5% respectively after 10 days of retention time. The mean production values obtained after digestion for the mode of digestion recommended for our local populace gave 2.4cm 3 of biogas per m 3 of digester vol/day and 1900mg/1 of discharged solids.