Feasibility of ultrafiltration-based processes for simultaneous removal of trace-level ofloxacin and sulfamethazine from the effluent of WWTPs

The emergence of emerging contaminants, especially antibiotics, poses a great challenge to the traditional treatment processes in wastewater treatment plants (WWTPs) due to their non-biodegradable and toxic properties. In this study, the potential of UF-based processes for concurrently removing trace-amount (ng/L-μg/L) ofloxacin (OFC) and sulfamethazine (SMT) from the real effluent of WWTPs was assessed. The operational conditions of single UF were firstly optimized including molecular weight cut-off (50 kDa) and filtration pressure (25 kPa) with the maximum OFC and SMT retention of 60.65 ± 1.61 % and 50.21 ± 2.11 %, respectively. The impacts of dissolved organic matter (DOM) and NO₃⁻ on UF for the concurrent abatement of antibiotics were explored. It was noteworthy that DOM (below 25 mg/L) could enhance OFC abatement by UF, whereas NO₃⁻ was adverse for the concurrent abatement of OFC and SMT. The optimal combining sequence of UF and O₃ processes for concurrently removing OFC and SMT from the effluent of WWTPs was also investigated. Compared with O₃-UF, UF-O₃ demonstrated a higher efficiency for concurrent elimination of OFC and SMT. The tech-economic feasibility analysis indicated that UF-O₃ could provide one promising option for simultaneously removing OFC and SMT from the WWTPs effluent due to its relatively low potential ecological risks based on UV₂₅₄ removal, acute toxicity and three-dimensional fluorescence spectroscopy (3D-EEM) and excellent cost-effectiveness (the operating cost is about 0.35 CNY/m³).