Boosted chloramphenicol mineralization and detoxification of UV/S(IV) processes with straightforward aeration: The critical contribution of post-reoxygenation

Abstract

Although advanced reduction processes (ARPs) based on UV/S(IV) (UV/sulfite) processes could achieve higher dechlorination and degradation efficiencies for organic pollutants, the mineralization and detoxification efficiencies still need to be further improved. In this study, post-reoxygenation was employed to improve the mineralization and detoxification of chloramphenicol (CAP) in UV/S(IV)-ARPs. The effects of initial pH and aeration rate on the dechlorination and mineralization efficiency of CAP were investigated. At the optimized conditions (pH 3.0, aeration rate of 0.3 L min−1), 92.75 % of dechlorination efficiency and 29.3 % of COD removal were obtained after 2 h of reoxygenation. Meanwhile, the effects of inorganic anions (Cl-, SO42-, HCO3–, NO3–, and HPO42-) on the removal of COD and dechlorination efficiency were also evaluated. Furthermore, the electron paramagnetic resonance analysis disclosed that SO4•- and HO• mainly contributed to the mineralization of CAP. Further degradation and mineralization of CAP were confirmed in the post-reoxygenation UV/S(IV)-ARPs (PRO-UV/S(IV)-ARPs) and the intermediates were identified. The ecotoxicity prediction and residual toxicity assessment revealed that the ecotoxicity of CAP solution was significantly reduced after the treatment of post-reoxygenation. Overall, the PRO-UV/S(IV)-ARPs provides a promising choice with straightforward operation for the purification and detoxification of CAP wastewater.