Biohydrogen production from palm oil mill effluent using immobilized Clostridium butyricum EB6 in polyethylene glycol

► PEG was used to entrap Clostridium butyricum EB6 for H2 production from POME. ► Acclimation of immobilized cells improved the H2 production. ► Repeated tests showed the strength of immobilized cells for stable and high H2 production. ► Optimal PEG beads dosage and size were tested.