Reduction of N2O emission in wastewater treatment by modified basalt fiber bio-nest technology

Aerobic/anoxic/anaerobic genera were distributed in all layers of the bio-nest, and denitrification genera had higher relative abundance in the MBF bioreactor than in the SBR, which facilitated denitrification and mitigated the accumulation of intermediate products, reducing N2O emissions. The MBF bio-nest reactor had the highest TN removal rate of 86.64%±1.14% and the lowest N2O emission of (0.4±1.0) mg N2O/g TN when the DO concentration was 2.5mg/L (M2).

The bio-nest microbial genus categories were basically the same in each DO gradient, but differed in their relative abundance. In M2, HN-AD bacteria were the main nitrifying functional bacteria in the reactor (the relative abundance of the layers from inside to outside was 44.24%, 61.34%, and 36.16%), which was conducive to N2O reduction; HDN were the main functional bacteria in the M2reactor, with moderate relative abundance of 20.17%, 12.00%, and 21.20% from inside to outside layers; the concentrations of NO2--N and NO3--N in the effluent were (0.011±0.002) and (1.65±0.46) mg/L; denitrification was carried out completely, which was conducive to the reduction of N2O emissions.