Enhanced removal of emerging contaminants using persulfate activated by UV and pre-magnetized Fe0

Abstract

Emerging contaminants (ECs) have been frequently detected in the aquatic environment and have adverse effect on the environment. In our present study, four ECs (800 μgL−1 oxytetracycline (OTC) and tetracycline (TC); 400 μgL−1 sulfadiazine (SD) and sulfamethazine (SMT)) spiked into the secondary wastewater effluent (SWE) were treated by novel UV/pre-magnetized Fe0/PS process (UV/pre-Fe0/PS). TC, OTC and SMT could be completely removed within 30 min and 98.4% SD could be removed within 60 min, while less than 10%, 20% and 60% ECs could be removed by Fe0/PS, pre-Fe0/PS and UV process within 60 min. Synergetic factor values (6.1–12.3) in UV/pre-Fe0/PS were much larger than in UV/Fe0/PS (2.3–5.4) to remove various ECs, achieving 0.7–2.2 times enhancement in degradation rate constants and 45%–86% reduction in treatment costs. EPR spectra and scavenging tests by tert-butyl alcohol and methanol confirmed that not only faster and more SO4− and OH radicals were produced but also their contributions to SMT removal were enhanced. Optimization of dosage of Fe0 (0–0.4 mM) and dosage of PS (0–0.4 mM) indicated that 0.2 mM Fe0 and 0.2 mM PS was the optimal dosage. Meanwhile, this process not only could enhance 0.7–15.8 times degradation rate constant but also could reduce about 14.3–97.9% costs to remove various ECs compared with US/Fe0/PS, ozonation, VUV/UV/Fe3+ and UV/H2O2 process. Moreover, it could enhance 1.4 times of degradation rate constant and reduce about 62% cost to remove SMT in another SWE, indicating the applicability in different wastewaters. Therefore, UV/pre-Fe0/PS process is promising and cost-effective to remove ECs in SWEs.