Applying multiple bio-cathodes in constructed wetland-microbial fuel cell for promoting energy production and bioelectrical derived nitrification-denitrification process

Abstract A multiple bio-cathodes constructed wetland-microbial fuel cell (CW-MFC) system, aiming for higher power production and therefore the improved N removal, was investigated in this study. As the bio-cathode number increased from 1 to 3, the energy losses on both anode and cathode showed a significant decrement (from 97.85 mV to 46.09 mV for anode and from 221.5 mV to 45.89 mV for cathode, respectively). Accordingly, the maximum power density of the system showed a notable increase from 12.56 to 26.16 mW/m 2 . In addition to the improved electrical performance, enhanced simultaneous nitrification & denitrification process was triggered due to the influence of the bioelectrical derived interaction between power production and systematic nitrification rate ( r Ni ) and denitrification rate ( r De ). Insight into the nitrification & denitrification process has been given that r Ni increased from 98.59 ± 4.53 mg/(m 2 ·d) of the control system to 179.11 ± 7.65 mg/(m 2 ·d) of three bio-cathodes system while r De increased from 89.64 ± 4.57 mg/(m 2 ·d) to 163.55 ± 11.88 mg/(m 2 ·d). Correction analysis showed that the amount of electrical related nitrogen removal is almost linearly correlated to the produced electricity. Overall, this study presented a promising strategy and provided insight for higher energy production and the enhanced nitrogen removal from the newly established CW-MFC system.