Enhanced wastewater treatment and electricity generation using stacked constructed wetland–microbial fuel cells

Water pollution and energy production are major issues in the context of climate change, urbanization and industrialization. There is need for cost-effective and sustainable processes for wastewater treatment. Here we designed a novel system made of a stack of 12 vertically-arranged constructed wetlands coupled with microbial fuel cells. Performance was evaluated in terms of chemical oxygen demand (COD) removal, NH4+–N, NO3−–N, and PO4−3 removal efficiency, and electricity generation. The results reveal that the efficiency of COD removal  increased gradually with decreasing external resistance, reaching 98.5% at 0.08 kΩ. The maximum removal efficiency was 90.4% for NH4+–N at 15 kΩ and 86.9% for NO3–N at 0.08 kΩ. The maximum power density reached 30.85 mW/m3 at 15 kΩ.