Optimization of Enzymatic Pretreatment Process for enhanced Biogas Production from Palm Oil Mill Effluent
Anaerobic digestion (AD) of palm oil mill effluent (POME) for biogas production by four sequential processes such as hydrolysis, acidogenesis, acetogenesis and methanogenesis in which hydrolysis is considered as a rate-limiting step. To achieve high yield of biogas in the AD, enzymatic hydrolysis as the pretreatment method was applied to over the current limitation of the existing plants. Therefore, an optimization study was carried out to evaluate AD performance for biogas production. Among the parameters, three factors i.e. cellulase enzyme dose, pH and total suspended solids (TSS) were studied by the face-centered central composite design (FCCCD) under the response surface methodology (RSM) based on lipase pre-treated POME. The results showed that the maximum of 835 ml biogas was obtained with 85% COD removal rom 50 ml of POME substrate after 10 days of operation while 290 ml biogas produced from control (without pretreatment). The optimum process conditions were at pH 5 and TSS of 1.5% and enzyme loading 200 CMC/ml. High coefficient of (R2) value of 0.994 indicated a satisfactory fit of the model.