Optimization of an A²/O process for tetracycline removal via response surface methodology coupled with a Box–Behnken design

Abstract

Response surface methodology (RSM) was used to optimize the operating conditions of an anaerobic-anoxic-oxic (A²/O) process by maximizing the removal efficiency of tetracycline (TC). Solid retention time (SRT), hydraulic retention time (HRT) and initial TC concentration (C_{TC, in}) were selected as independent variables for incorporation in the Box–Behnken design. The results showed SRT and C_{TC, in} were more significant parameters than HRT for the removal efficiency of TC. TC could be completely removed under the optimal conditions of an SRT of 15.5 days, an HRT of 9.9 h and a C_{TC, in} of 283.3 μg L⁻¹. TC removal efficiencies of 99% and 96% were attained for synthetic and real wastewater, respectively, under the optimal conditions. This indicated the constructed model was validated and reliable for optimizing the A²/O process for TC removal.

Keywords:

• Anaerobic-anoxic-oxic (A²/O)
• Box–Behnken design
• operating conditions
• response surface methodology (RSM)
• tetracycline

Funding

The authors would like to thank the National Natural Science Foundation of China (No. 21477018, 21007010); Hu Nan province Ministry of Transportation Scientific Research Project (No. 200908, 201105) and Ministry of Transport Science and Technology Program (No. 2010353343290).