Membrane penetration of nitrogen and its effects on nitrogen removal in dual-chambered microbial fuel cells

Owing to membrane penetration, a novel route of nitrogen removal was proposed in a dual-chamber microbial fuel cell with a proton exchange membrane (PEM). The results showed that NH₄⁺-N rapidly migrated across PEM with a mass transfer coefficient (K_A) of 1.79 ± 0.51 × 10^-4 cm s^-1, 50% of which was oxidized to NO₃^--N in the cathode chamber, then the remainder being eliminated by short-cut nitrification/denitrification. Meanwhile, NO₃^--N went across the PEM again with a low K_A of 5.50 ± 0.24 × 10^-6 cm s^-1, and was subsequently reduced via anodic denitrification. In the anode, the functional microorganisms were divided into exoelectrogenic bacteria (46.2%) and denitrifying bacteria (37.3%), while the dominated bacteria were mainly affiliated with nitrifying bacteria (19.6%) and aerobic denitrifying bacteria (52.9%) in the cathode. These findings provide a new insight into nitrogen removal during bioelectrochemical treatment of actual wastewater.