Simultaneous Removal of Nitrate and Tetracycline by an Up-Flow Immobilized Biofilter

The removal of nitrate (NO3--N) and antibiotics in aquaculture tail water is urgent and necessary. A lab-scale up-flow immobilized biofilter (I-BF) filled with polyurethane foam (PUF) carriers and a microbial consortium was developed for simultaneous removal of nitrate and tetracycline (TC). The denitrification and TC removal performance of the I-BF reactor was investigated under different TC concentrations (0, 10, 50, 100 mg center dot L-1), carbon/nitrogen (C/N) ratio (2, 4, 5, 6) and hydraulic retention times (HRT) (4, 8, 12 h). Simultaneous removal of nitrogen and TC was achieved by the I-BF reactor. Low TC concentration (<= 50 mg center dot L-1) had little effect on nitrogen removal. The denitrification performance of the I-BF reactor was inhibited at high TC load, which may be attributed to the damage of cell membranes and the inhibition of the intracellular denitrification enzymes' activities. The optimal C/N ratio and HRT were 5 h and 8 h with almost complete denitrification and high TC removal efficiency (73.46%) at influent NO3--N and TC concentrations of 100 mg center dot L-1 and 50 mg center dot L-1, respectively. The I-BF reactor proposed in this study has promising applications such as the treatment of piggery wastewater, aquaculture tail water and pharmaceutical wastewater co-contaminated with nitrate and antibiotics.

Automated summary

In this study, a lab-scale up-flow immobilized biofilter (I-BF) was developed for simultaneous removal of nitrate and tetracycline (TC) in aquaculture tail water. It was found that the denitrification performance of the I-BF reactor was inhibited at high TC load. The optimal conditions for denitrification and TC removal were a C/N ratio of 5 and a HRT of 8.