Insight in degradation of tetracycline in mariculture wastewater by ultraviolet/persulfate advanced oxidation process

The direct discharge of trace amounts of antibiotics in mariculture wastewater results in adverse effect on the ecological environment of receiving waters. Hence, the degradation of tetracycline (TC) in mariculture wastewater by the ultraviolet/peroxydisulfate (UV/PS) process was investigated in this study. The results revealed that 95.73% removal of TC with 5 mg/L dosage was achieved after 30 min UV/PS treatment. Chloride ion (Cl−) in mariculture wastewater slightly inhibited TC degradation by scavenging free radicals. Comparably, bromine ion (Br−) significantly enhanced the removal of TC and even doubled the degradation rate. Reactive bromine species (RBS) made a major contribution to the TC removal, followed by free chlorine and other reactive chlorine species (RCS). The TC degradation pathway revealed that functional group shedding and ring-opening reactions occurred successively. In addition, TC mineralization rate was low within 30 min, causing the inefficient reduction of acute toxicity of TC and its intermediates, which could be improved by optimizing the process parameters. These results indicated that UV/PS is a new alternative process for the harmless treatment of mariculture wastewater containing the antibiotics.