Shortage of energy and pollution of water are two concern global issues. The treatment of polluted water usually requires a lot of energy. The demand for wastewater treatment and energy shortage has attracted the interest of research on converting pollutants to energy. Constructed wetland (CW) is environmentally friendly technology developed for the purification of polluted water and microbial fuel cell (MFC) is biotechnology that could turn organic pollutants into electricity. Hence, this paper aimed to identify the advantage of integrating MFC into CW through the study of the closed and open circuit on the wastewater treatment performance as well as the effect of spacing between cathode and anode on the generation of electricity in up-flow constructed wetland coupled microbial fuel cell (UFCW-MFC) system. The wastewater treatment performance was evaluated through the analysis of COD. The total COD removal efficiency was 99%. The closed circuit improved 10.9% compared to the open circuit at the anaerobic compartment (S1) in terms of COD removal. The effect of electrode spacing was investigated by comparing the maximum power density produced by three different electrode spacing between cathode and anode (15, 30, 45 cm). The highest maximum power density was achieved at the smallest spacing of electrode (15 cm), which recorded 73.48 ± 0.31 mW/m3. In conclusion, the MFC feature (closed circuit) improved the organic matter degradation and smaller electrode spacing benefits the energy production in UFCW-MFC.
