Pesticide production wastewater treatment by Electro-Fenton using Taguchi experimental design

Abstract

In this study, the electro-Fenton (EF) method was applied to remove total organic carbon (TOC) from the pesticide production wastewater containing tricyclazole (TC). Statistical Taguchi method was used to optimize the treatment performance. Analysis of variance (ANOVA) indicated that the polynomial regression model fitted experimental data with R2 of 0.969. The optimal conditions for eliminating 75.4% TOC and 93.7% TC were 0.2 mM of Fe2+, 990 mg/L of Na2SO4, 180 min of reaction time at pH 3 with 2.22 mA/cm2 of current density. The removal of TC present in the wastewater followed the first-order reaction kinetic model (R2 = 0.993); while that was the second-order kinetic model in the case of the TOC removal (R2 = 0.903). In addition, the experimental results and theory approaches (density functional theory and natural bond orbital calculations) also showed the C-N bond breaking and nitrate ions cleavage to ammonia. Acute toxicity of the pesticide wastewater after treatment (PWAT) on microcrustaceans showed that the treated wastewater still exhibited high toxicity against D. magna, with LC50 values of 3.84%, 2.68%, 2.05%, and 1.78% at 24 h, 48 h, 72 h, and 96 h, respectively. HIGHLIGHTS Electro-Fenton (EF) was employed to remove TOC and tricylazole from real pesticide wastewater.; Taguchi approach (L27) had been developed on five factors of EF on TOC removal.; ANOVA showed a well-fitted polynomial regression model with R2 of 0.969.; The nitrogen minerals reached 25.3 as explained by DFT/NBO calculations.; Cost analysis, kinetic reaction of EF process and bioassay toxicological test also evaluated.;

Keywords

• d. magna
• electro-fenton
• pesticide
• taguchi method
• tricylazole