Statistical optimization of industrial textile wastewater treatment by electrochemical methods

In this work, the Box–Behnken experimental design and the surface response methodology were applied for the optimization of the operational conditions of the electro-catalytic degradation of wastewaters, resulting from a local textile industry. The experiments were carried out in a laboratory scale batch cell reactor, with monopolar configuration, and electrodes made of boron-doped diamond (anode) and titanium (cathode). The multifactorial experimental design included the following variables: current density (i: 5–10 ?mA/cm2), pH (3–7), and submerged cathode area (CA: 8–24 ?cm2). To determine the process efficiency, the degradation percentage of: the chemical oxygen demand (%DCOD), the total organic carbon (%DTOC) and the color (%DC) were defined as response variables. The following optimal conditions for the electro-oxidation (EO) process were obtained: i ?= ?10 ?mA/cm2, pH = 3 and CA ?= ?16 ?cm2, reaching ca. 92 ?% of DC, 37 ?% of DCOD and 31 ?% of DTOC. The electro-Fenton (EF) and photo-electro-Fenton (PEF) processes were also evaluated at EO optimal conditions. For the EF process, with addition of iron (0.3 ?mM), the %DC, %DCOD and %DTOC was enhanced to 95, 52 and 45 ?%, respectively. For the PEF process (UV ?= ?365 ?nm), it was possible to reach 98 ?%DC, 56 ?%DCOD and 48 ?%DTOC. © 2014, Springer Science+Business Media Dordrecht.