Effects of different concentrations of sulfamethoxazole on nitrogen metabolism in vertical flow constructed wetland

The effects and mechanism of low concentrations (1 mg center dot L-1) and high concentration (10 mg center dot L-1) of sulfamethoxazole (SMX) on nitrogen metabolism in vertical flow constructed wetland (VFCW) were analyzed. The removal efficiencies of 1 and 10 mg center dot L-1 SMX in VFCW were found to be 98.92 +/- 2.74% and 58.63 +/- 12.86%, respectively. SMX suppressed the removal of NH4+-N (93.90%-> 93.44%-> 92.54%), but significantly increased NO3--N removal (66.62%-> 94.63%-> 89.39%, p < 0.05). Metagenomic analysis certified that 10 mg center dot L-1 SMX had a remarkable repression effect on the abundance of amoABC (p < 0.05) and the dissimilatory nitrate reduction was strengthened. Conversely, 1 mg center dot L-1 SMX remarkable inhibition expression of hao and the dominant role of nitrogen functional gene of amoC, narGHI and napAB were significantly enhanced. Moreover, SMX enhanced clustering of microbial communities, and the structural stability was proportional to the concentration of SMX in VFCW.