Effect and ameliorative mechanisms of polyoxometalates on the denitrification under sulfonamide antibiotics stress

The environmental risks of the sulfonamide antibiotics have attracted much attention recently. In this study, the inhibition effects of sulfadiazine (SDZ) on denitrification electron transfer system (ETS) and ameliorative mechanisms of phosphomolybdic acid (PMo12) were first explored. When denitrification was under 2 mg/L SDZ stress, experiments indicated that PMo12 enhanced NO3–-N reduction efficiency and rate from 68.30% to 100.00% and 124.22 to 184.59 N/g VSS/h, respectively. Electron transfer rate and consumption efficiency in denitrification ETS were enhanced to ameliorate SDZ inhibition, which was due to the more secreted riboflavin and cytochrome c and the increased denitrifying enzymes activity with PMo12 mediation. In addition, the microbial growth inhibition and cell membrane damage were ameliorated due to the more EPS surrounding microbe with PMo12 mediation. Higher diversity of denitrifying microbe with PMo12 mediation also promoted denitrification under SDZ stress. This work provided promising strategy to ameliorate antibiotics inhibition in the wastewater bio-treatment.