UV-activated persulfate oxidation of 17β-estradiol: Implications for discharge water remediation

Abstract

The female sexual hormone, 17β-estradiol (E2), was chosen as a model emerging contaminant to study its degradation kinetics using UV-activated persulfate (UV/PS). Our objective was to quantify the effectiveness of UV/PS coupled with slow-release technology to degrade E2 in real wastewater using a systematic design flow-through system. This was accomplished by quantifying the effects on E2 degradation rates of the initial PS or E2 concentration, initial pH, constituent ions, turbidity, humic acids, and real wastewater. The results showed that the E2 degradation rates increased with increasing PS concentration. The presence of other constituent ions (NO3−, Cl−, HCO3−) resulted in varying degradation rates due to the formation of active and less reactive radicals. Humic acid had higher significant impact on the rates than did turbidity. In addition, the observed degradation rates (0.140 min−1) in Deionized water were much higher than those observed in real wastewater matrix (0.001 min−1). Biodegradable soywax was the best binding agent that provided sustained delivery of PS thus resulting in better E2 removal than with other waxes. But treating E2 with PS soywax in a wastewater matrix, our flow-through system was able to maintain the E2 concentration below 50% in the contact tank (˜150 min) and able to continually remove E2 up to 65% (˜240 min) in the effluent reservoir. The overall results supported the use of UV-activated slow-release PS to treat discharge water in animal farming.