Mitigation of nitrous oxide ( N 2 O ) emission from swine wastewater treatment in an aerobic bioreactor packed with carbon fibers

Mitigation of nitrous oxide ( N 2 O ) emission from swine wastewater treatment was demonstrated in an aerobic bioreactor packed with carbon fibers ( CF reactor). The CF reactor had a demonstrated advantage in mitigating N 2 O emission and avoiding NOx ( NO 3  +  NO 2 ) accumulation. The N 2 O emission factor was 0.0003 g N 2 O ‐ N / gTN ‐load in the CF bioreactor compared to 0.03 g N 2 O ‐ N / gTN ‐load in an activated sludge reactor ( AS reactor). N 2 O and CH 4 emissions from the CF reactor were 42 g‐ CO 2 eq/m 3 /day, while those from the AS reactor were 725 g‐ CO 2 eq/m 3 /day. The dissolved inorganic nitrogen ( DIN ) in the CF reactor removed an average of 156 mg/L of the NH 4 ‐ N , and accumulated an average of 14 mg/L of the NO 3 ‐ N . In contrast, the DIN in the AS reactor removed an average 144 mg/L of the NH 4 ‐ N and accumulated an average 183 mg/L of the NO 3 ‐ N . NO 2 ‐ N was almost undetectable in both reactors.