Effects of different pretreatment methods on anaerobic mixed microflora for hydrogen production and COD reduction from palm oil mill effluent

Effects of different pretreatment methods on sludge inocula were evaluated with respect to hydrogen (H2) production enhancement using palm oil mill effluent (POME) in a batch system. The experimental results showed that the pretreatment methods (chemical, acid, heat-shock, freezing and thawing, and base) at 35 °C and initial pH 5.5 had a positive influence on H2 production yield and chemical oxygen demand (COD) removal efficiency during the fermentative H2 production as compared to the control experiments (without pretreatment). Heat-shock pretreatment method was shown to be a simple and useful method for enhancing both H2 producing and COD removal processes from POME with highest H2 yield and COD removal efficiency at 0.41 mmol H2/g COD and 86%, respectively.