Identification and cultivation of hydrogenotrophic methanogens from palm oil mill effluent for high methane production. Palm oil mill effluent for high methane production

By means of biorefinery, biogas production through anaerobic digestion is one of the most common treatment of wastewater in palm oil industry. After biogas production, treated palm oil mill effluent (POME) is generally discharged into the environment. However, certain level of hazardous compounds still exists in the treated wastewater which can lead to pollution of waterbodies. In this study, we have investigated the dynamics of volatile organic acids dwelling in consecutive POME treatment lagoons as well as identified and categorized microbial species responsible for the treatment process. Bacteria and, both hydrogenotrophic and acetoclastic, methanogens related to methane production were identified using mcrA and 16S rRNA genes specific primers. Two hydrogenotrophic methanogens; Methanoculleus marisnigri and Methanoculleus chikugoensis, were found abundant in accordance with high formate concentration throughout the process of anerobic digestion. This study has also isolated eight consortia of microbes that yielded different methane productions by utilizing formate as the substrate in the synthetic medium. The consortia of a group containing M. marisnigri, M. chikugoensis, uncultured bacteria, Aminobacterium sp., and Ruminobacillus xylanolyticum, produced the highest methane yield of 259 mL/g COD after 25 days of incubation in the laboratory. The findings from this study are contributing to optimize and increase biogas production in POME which will allow higher efficiency in palm oil mill wastewater treatment.