Palm Oil Mill Effluent (POME) utilization for bio-hydrogen production targeting for biofuel : optimization and scale up

¹ Center for Energy Resources Technology and Chemical Industry, Agency for the Assessment and Application of Technology
² Center for Information and Communication Technology, The Agency of Assessment and Application of Technology
³ Department of Chemistry, Faculty of Science and Technology, Jambi University

Abstract

Indonesia is the largest palm plantation that reaches 32 million tonnes palm oil production per year with 84 million tones Palm Oil Mill Effluent (POME) as liquid waste. POME contains many organic substances. The quality of POME for its utilization is generally measured in COD which has range 30000 -100.000 ppm. Microbial convertion for biogas especially for bio-H₂ enrichment, the active sludge was pretreated physically to suppress methanogenesis microbes. H₂ Biogas production was conducted at pH 5-6. Additional 10% phosphate buffer was done in the beginning only. The production of H₂ biogas was influenced by hydrostatic pressure in closed batch system. Inoculumsmedium ratio also influenced the H₂ biogas productivity, reached 0.7 ml/ml POME with more than 50% H₂. Scaling up anaerobic in 2.5 L working volume bioreactor, H₂ biogas productivity reached 0.86 ml/ml POME by 10% inoculums because of no hydrostatic pressure. In bio-reactor, H₂-CO₂ in H₂ biogas was affected by the amount of active sludge. In the beginning of H₂ biogas, H₂ reached 80%. However, at subsequence process, fed batch, with retention time 2.5 day and 3 days H₂ biogas production, the active sludge was accumulated and caused the decreasing H₂, finally only 46% at the 3^rd day. The consortium tended to produce more CO₂ as the result of primary metabolite rather than H₂. Raising inoculums to level 15% improved productivity only in the beginning but H₂ content was getting less, only 59%. Additional feeding would cause more accumulation sludge and more decreasing H₂ content to 31% on the 3^rd day. Thus, the ratio of active sludge and substrate availability must be controlled to gain optimum H₂. Limited substrate will cause the direction of bio-conversion more in CO₂ rather than H₂.