Ahmad, AdriantoBahrudinZul Amraini, SaidAndrio, David2013-05-082013-05-082013-05-081907-0500wahyu sari yenihttp://repository.unri.ac.id:80/handle/123456789/3296The performance of anaerobic processes in the bioconversion of palm oil mill effluent into gaseous fuel is very dependent on the concentration of biomass. Effort to increase the concentration of anaerobic biomass can be done by using anaerobic hybrid bioreactor. The bioreactor used had 3 chambers, each divided for an up and down flow pattern and having a working volume of 2,5 m3. Several series of experiments were conducted with variable hydraulic retention time (HRT) of 1; 1,5; 2; 2,5; 3; 3,5; 4 and 5 day under room temperature conditions and continuous operation. This study uses two anaerobic hybrid bioreactors equipped with cell immobilization media. Media used in cell immobilization is a medium density form of solid palm oil mills waste, namely: empty fruit bunch and palm midrib. The results showed that the anaerobic hybrid bioreactor system was capable of converting single-phase oil palm mill effluent with a good performance, and high organic loading rate of COD removal efficiency of 84% for the bioreactor with palm midrib media and 88% for the bioreactor with empty fruit bunch media within bioconversion of one day and the stability of the bioreactor is relatively high so as to convert liquid waste into fuel gas.enHRTsingle-phasethe anaerobic hybrid bioreactorwastewaterUR-Proceedings