Effect of Tetracycline on Nitrate Removal by Simultaneous Heterotrophic Aerobic Denitrification

In the recirculating aquaculture systems, the aerobic biotreatment strategy for influent is frequently adopted to avoid poisonous byproducts produced under anaerobic conditions. However, residue antibiotics and nitrogenous compounds accumulate in mariculture wastewater and little is known about the effect of antibiotics on heterotrophic aerobic denitrification. Therefore, we designed a laboratory-scale aerobic bioreactor and investigated the effect of tetracycline (TET) on simultaneous nitrate (NO3−-N), ammonium (NH4+-N), nitrite (NO2−-N), chemical oxygen demand (COD), and TET removal, an aerobic denitrification system feeding with 148 mg/L COD, 14 mg/L NO3—N, and 100–200 μg/L TET was setup. Results obtained from the study showed that the maximum removal efficiency for COD, NH4+-N, NO2−-N, and TET was 100%, 95.45%, 84.66%, and 70.68% respectively. Denitrifiers were inhibited by an increase in TET. In addition, TET degradation was highest in bioreactor B where it reached 70.68% possibly due to the existence of genera like Woesearchaeales, Thauera, Denitratisoma, Sulfuritalea, and Methylotenera, which were enriched by an initial TET dosage of 150 μg/L. The findings of this research indicated that heterotrophic aerobic denitrification is an efficient technology for simultaneously removing NO3−-N, NH4+-N, NO2−-N, COD, and TET from mariculture wastewater.