Optimization of solar-driven photo-electro-Fenton process for the treatment of textile industrial wastewater

Abstract

This work deals with the evaluation of a solar-driven Photo Electro-Fenton (SPEF) process as an alternative for the effective degradation of an industrial textile wastewater sample. Experiments were carried out in a laboratory scale batch cell reactor, using boron-doped diamond (anode) and titanium (cathode) electrodes in monopolar configuration. The effect of the main operational parameters (pH, current density (j), conductivity (ơ), Fe2+ concentration and anode area to effluent volume ((A/V) ratio) on the COD removal and energy consumption were studied using a Box-Behnken experimental design. The SPEF process was optimized using the Response Surface Methodology. At optimum operational conditions (pH = 4, j = 40 mA/cm2, ơ = 5768 μS/cm and Fe2+ = 0.3 mM), the solar-driven process achieved total discoloration, COD reduction of 83% and TOC mineralization of 70%, after 15 min of electrolysis. The process yielded a highly oxidized (AOS = 2.24) and biocompatible (BOD5/COD > 0.4) effluent. Additionally, the most suitable effective surface area of the electrodes (A/V ratio) was determined (3.75 m−1). The analysis of operational costs was also performed. The SPEF process demonstrated to be an efficient alternative for the treatment of industrial wastewater effluent, allowing to achieve Colombian permissible discharge limits.