A comparative study of electrocoagulation, electrochemical Fenton, electro-Fenton and peroxi-coagulation for decolorization of real textile wastewater: Electrical energy consumption and biodegradability improvement

• Iron as a dominant agent was utilized in four separate electrochemical processes.
• BOD5/COD ratio increased from 0.137 to 0.362 in electro-Fenton process.
• Color and COD removals were higher than 94% and 82% in electrochemical Fenton.
• Combination effect of coagulation/oxidation mechanisms raised k value (×10) in ECF.

The main problem of textile wastewater is strong color which must be removed before discharge to the environment. Electrochemical processes have been separately studied for decolorization of synthetic dyes and colored wastewater. In this study, iron-based electrochemical processes including electrocoagulation (EC), electrochemical Fenton (ECF), electro-Fenton (EF) and peroxi-coagulation (PC) were applied for real textile wastewater decolorization in similar conditions. The effects of initial pH, electrical current and electrolysis time on decolorization were evaluated. COD removal, electrical energy consumption, iron consumption and BOD5/COD ratio of each process were compared. All the processes sufficiently removed color from the wastewater in as much as between 77% and 94% decolorization efficiency was gained. The results indicated that decolorization efficiency in EC and EF processes was strongly dependent on initial pH. At optimum conditions, the highest energy consumption and iron consumption were found in EF and PC respectively. Electrochemical processes based on Fenton reagent (ECF, EF and PC) enhanced BOD5/COD ratio from 0.137 to over 0.3 while EC process could not increase BOD5/COD ratio significantly. All the processes followed the second order kinetic for COD parameter in optimum conditions. As a comparison from the obtained results, the ECF process was more effective than the other processes with regard to color and COD removals.