Elucidating the relation between residual oxidants formation behavior and quinolone antibiotic removal efficiency on catalytic ozonation in seawater-based aquaculture wastewater

Abstract

Owing to the recent developments in aquaculture, the discharge of antibiotic-laden wastewater has become a growing concern. Quinolone antibiotics, which cause central nervous system and cardiac conduction disorders, are commonly detected in aquaculture wastewater. To remove antibiotics in wastewater, the ozone process is a commonly utilized method. In the process of seawater ozone treatment, bromide ions (Br−) produce total residual oxidant, such as hypobromous acid (HOBr). However, the oxidation potential of the total residual oxidant (TRO) is lower than that of ozone, and the presence of inhibitors, such as ammonium, and dimethyl sulfide can reduce the residual oxidant concentration. Therefore, the seawater ozone process requires a higher ozone injection than freshwater. In this study, various factors affecting TRO production were evaluated to determine the optimal ozone-catalytic process using gamma-alumina and elucidate the relationship between TRO production and antibiotic removal efficiency for efficient seawater-based wastewater treatment. The removal rates of representative quinolone antibiotics, such as enrofloxacin, ciprofloxacin, and oxolinic acid, were evaluated using liquid chromatography-fluorescence detection. The addition of a catalyst enabled the reaction to maintain a higher TRO concentration and improves antibiotic removal efficiency, even in the presence of ammonium in the aquaculture wastewater with the same ozone dosage applied. The results reveal that the ozone-catalyst process contributes to increased TRO production to suppress bacterial growth and effectively remove non-degradable organic matter, such as antibiotics, in seawater-based wastewater treatment.