Simultaneous removal of organic matter and inorganic nitrogen in Baijiu wastewater by methanothrophic denitrification

Methanotroph could facilitate nitrogen removal during methane oxidation, and promote conversion of various organic compounds by producing methane monooxygenase. Co-metabolic effect and mechanism of aerobic methane oxidation on the removal of nitrogen and organic matter from Baijiu wastewater were investigated using an improved denitrifying biological filter. It was found that the average removal efficiency of COD, NH4+-N, TN and color increased by 16.77%, 8.73%, 22.12% and 10.36%, respectively, in reactor B with methane gas compared to reactor A with air only. Three-dimensional fluorescence spectroscopy and Fourier transform infrared spectroscopy analysis revealed that methanotroph co-metabolism was accompanied by eliminating nitrogen and organic matter as well as forming alcohol compounds. Metagenomic analyses revealed that Methylocaldum, the dominant genera in Reactor B, exerted a pivotal role in removing nitrogen and organic matter removal by supplying energy and catalysis. Functional genes pmoABC-amoABC could facilitate nitrogen and organic matter removal.