Pretreatment of printing and dyeing wastewater by Fe/C micro-electrolysis combined with H2O2 process

A novel iron-carbon (Fe/C) micro-electrolysis combined with H2O2 (ICMH) process was proposed to pretreat the printing and dyeing wastewater (PDW), using a micro-electrolysis filling. The effects of H2O2 concentration, reaction time, initial pH, and Fe/C dosage on chemical oxygen demand (COD) removal rate of PDW were optimized by response surface methodology (RSM). The maximum COD removal rate was approximately 77.65% after 186 min treatment, when the concentration of H2O2, initial pH and the dosage of Fe/C were 8.88 g/L, 1.5 and 837 g/L, respectively. Analysis of variance (ANOVA) showed a high coefficient of determination value (R-2 = 0.9780). And H2O2 concentration and initial pH were the key factors to improve the treatment effect. UV-Vis spectra indicated that a significant blue shift at 220 nm, attributing that fused aromatic hydrocarbons were degraded effectively. 3D-EEM spectra analysis showed that the water samples of PDW mainly contained three kinds of organic matter: refractory fulvic acid, soluble microbial metabolites and aromatic proteins, and the degradation rate of these was 81.76%, 53.78% and 70.83%, respectively.