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

AbstractThis 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 (1.13–1.14 m3 kg−1 COD d−1) and methane yield (4606–5018 mL CH4 L−1 POME d−1) were achieved with co-cultivation of N. oculata (2 mL/mL POME) and OPEFB (0.12 g/mL POME), 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 1.13–1.16 m3 kg−1 COD d−1. Aerobic and anaerobic treatment of POME after 7 d 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%).