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.

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, and 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 wastewater treatment plant. 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 for scaling up by a better knowledge in real aqueous matrices.

Optimization of the synthesis process of an iron oxide nanocatalyst supported on activated carbon for the inactivation of Ascaris eggs in water using the heterogeneous Fenton-like reaction.

An experimental design methodology was used to optimize the synthesis of an iron-supported nanocatalyst as well as the inactivation process of Ascaris eggs (Ae) using this material. A factor screening design was used for identifying the significant experimental factors for nanocatalyst support (supported %Fe, (w/w), temperature and time of calcination) and for the inactivation process called the heterogeneous Fenton-like reaction (H2O2 dose, mass ratio Fe/H2O2, pH and reaction time). The optimization of the significant factors was carried out using a face-centered central composite design. The optimal operating conditions for both processes were estimated with a statistical model and implemented experimentally with five replicates. The predicted value of the Ae inactivation rate was close to the laboratory results. At the optimal operating conditions of the nanocatalyst production and Ae inactivation process, the Ascaris ova showed genomic damage to the point that no cell reparation was possible showing that this advanced oxidation process was highly efficient for inactivating this pathogen.