Effects of electrode material and substrate concentration on the bioenergy output and wastewater treatment in air-cathode microbial fuel cell integrating with constructed wetland

•The CW-ACMFC systems operated with different substrate concentration was compared.•Average bioenergy produced in CW-ACMFC increased with substrate concentration.•Effect of plant photosynthesis on light-dark cycle of bioenergy output was analyzed.•NO3-N removal efficiency was promoted in CW-ACMFC with CFF and FN electrode material.

In the study, the effects of electrode material and substrate concentration on the bioelectricity generation and wastewater treatment performances in air-cathode microbial fuel cell coupled with constructed wetland (CW-ACMFC) systems were investigated. Four materials including carbon fiber felt (CFF), stainless steel mesh (SSM), graphite rod (GR), and foamed nickel (FN) were used as air-cathode and anode for each system. The obtained maximum power densities of Systems 1, 2, 3 and 4 were 4.80, 2.30, 3.35, and 5.11 mW m−2, respectively. In addition, a relative higher NO3-N removal efficiency was observed in four reactors, However, average COD removal percentages of Systems 1, 2, 3, and 4 were 42.30%, 37.42%, 48.78%, and 35.73%, respectively. The relative abundance of autotrophic denitrifying bacteria in the FN system was relatively higher. In summary, CFF and FN can be used as the electrode materials in the CW-ACMFCs system for wastewater treatment and bioelectricity generation simultaneously.