Thiabendazole degradation by photo-NaOCl/Fe and photo-Fenton like processes, using copper slag as an iron catalyst, in spiked synthetic and real secondary wastewater treatment plant effluents

Abstract

Thiabendazole degradation (TBZD) in diferent types of water matrices was assessed by applying two Advanced Oxidation Processes, both using simulated solar light (SSL), copper slag (CS) as an iron based catalyst, and separately H2O2 or NaOCl as oxidants. First, optimum conditions for TBZD were evaluated in distilled water, TBZD = 90% at 60 min for CS-H2O2-SSL, while 92% of TBZD in a twelfth of the time by the system CS-NaOCl-SSL; minimum TBZ-depletion variations, were observed between the first and the fifth reuse test: 88 ± 2% for CS-H2O2-SSL (60 min) and 90 ± 1% for CS-NaOCl-SSL (5 min). Those conditions were tested using a synthetic (SE) and a real secondary effluent (RE) from a WWTP. The CS-H2O2-SSL system achieved TBZD of 88 and 77%, after 90 min for SE and RE, with kinetic constants of 0.024 and 0.016 min−1, respectively. Whereas, photo-NaOCl/Fe showed values of 0.365 and 0.385 min−1 for SE and RE, achieving a 94% TBZD removal in both types of water at 10 min. That might be related to the formation of Cl· and HO• during the photo-NaOCl/Fe process, highlighting that the CS-NaOCl-SSL is an attractive option that has great possibilities to be scaling up by a better knowledge in real aqueous matrices.