Modeling and optimization of acid dye manufacturing wastewater treatment with Fentons reagent: comparison with electrocoagulation treatment results and effects on activated sludge inhibition

摘要

In the present study, Fenton’s oxidation of a chromium complex disazo dye (Acid Blue 193)nsynthesis wastewater was evaluated, modeled and optimized by employing Central CompositenDesign. Within this context, the individual and interactive effects of critical process parametersnsuch as Fe2+, H2O2 concentrations, initial chemical oxygen demand (COD) and reaction time wasnassessed. The process response (output) variables were chosen as percent color, COD and totalnorganic carbon (TOC) removal efficiencies. Optimum working conditions in terms of color andnorganic carbon removals were established to be Fe2+ ?3mM; H2O2 ?25mM; reactionntime ?10 min at pH 3 and an initial COD content of 245 mg/L. Under these conditions, 96% color,n82% COD and 51% TOC removals were obtained. The established polynomial regression modelsndescribing color, COD and TOC removals satisfactorily fitted the experimental data and could benused to predict Fenton’s treatment results at statistically significant rates. Optimized treatmentnresults were compared with those obtained via electrocoagulation treatment under optimizednconditions (applied current ?50 A/m2; reaction time ?15 min; initial pH ?7 for an initial CODncontent of 245 mg/L). The relative inhibition of heterotrophic oxygen uptake rate was measurednto examine the inhibitory effect of azo dye synthesis effluent before and after Fenton’s oxidationnand electrocoagulation with respect to synthetic domestic wastewater. Untreated azo dyenproduction wastewater exhibited a slightly inhibitory effect that was appreciably reduced but notnentirely removed after Fenton’s oxidation, whereas no inhibition of mixed bioculture wasnobserved for azo dye synthesis effluent subjected to electrocoagulation treatment.