Palm oil mill effluent treatment using hybrid microbial fuel cell-activated carbon system

Palm oil mill effluent (POME) is a thick brownish liquid which causes serious environmental pollution due to its high chemical oxygen demand (COD) and biochemical oxygen demand (BOD) and POME can contaminate watercourses if discharged without proper treatment. Hybrid microbial fuel cell-activated carbon system is an innovative and progressive technology that brings many advantages in treating wastewater effectively, economically and environmental friendly. This study aims to investigate the feasibility of treating POME using hybrid microbial fuel cell-activated carbon (MFC-AC) system with methylene blue as mediator. The viability of the hybrid MFC-AC system in generating voltage, power density and current was also investigated. The air-cathode single chamber MFC-AC hybrid system with and without mediator was fabricated and the characterization of raw POME and treated POME were conducted by using COD, BOD, total suspended solids (TSS), ammoniacal-nitrogen (AN) and turbidity tests to evaluate the efficiency of the hybrid MFC-AC system to treat POME. From this study, 286.5 mV and 137.6 mV of voltage were generated in MFC-AC system with and without mediator respectively when using 50 Ω external resistances. The current generation of 5.73 mA and 2.75 mA and power generation of 2506.5 mW/m3 and 577.9 mW/m3 were produced respectively by the MFC-AC system with and without mediator. Other than that, these systems were able to reduce BOD up to 85.42% (39.38 mg/L) and 78.6% (58 mg/L), and COD up to 92.72% (48 mg/L) and 87.41% (83 mg/L) in the hybrid MFC-AC system with and without mediator, respectively. The TSS removal was 96.64% (9 mg/L) and 92.31% (36 mg/L) while turbidity removal was 96.75% (9 NTU) and 90.6% (26 NTU) in the hybrid MFC-AC system with and without mediator, respectively. The maximum AN removal of 46.48% (114 mg/L) was obtained in the hybrid MFC-AC system with mediator while for the system without mediator, the AN removal was 39.91% (128 mg/L). Overall, the MFC-AC system fabricated in this study was feasible to be applied for POME treatment as the effluent concentration was able to comply with imposed by Department of Environment, Malaysia