Aerobic and anaerobic co-cultivation of Nannochloropsis oculata with oil palm empty fruit bunch for enhanced biomethane production and palm oil mill effluent treatment

This study explored co-cultivation of Nannochloropsis oculata microalgae with oil palm empty fruit bunch (OPEFB) for anaerobic biomethane production and palm oil mill effluent (POME) treatment. The highest specific biogas production rate (1.13-1.14m(3)kg(-1)COD d(-1)) and methane yield (4606-5018mL CH4 L-1 POMEd(-1)) were achievedwith co-cultivation of N. oculata(2mL/mLPOME) and OPEFB (0.12g/mLPOME), as similarly predicted by response surface methodology for optimum conditions. Without microalgae and OPEFB co-cultivation, the biomethane yield was 1.3-fold lower, although the specific biogas production rate remained constant at 1.13-1.16m(3)kg(-1)COD d(-1). Aerobic and anaerobic treatment of POME after 7d with microalgae achieved higher removal efficiency of COD (90-97%), BOD (84-98%) and TOC (65-80%) as compared to without microalgae with COD (58-68%), BOD (77-86%) and TOC (58-68%).