Textile dyeing wastewater treatment by coupling Fenton's reagent and aerobic sequential batch reactor processes

Abstract

The oxidation of organic compounds and color removal of a synthetic dyeing effluent when treated with a combination of Fentons Reagent and biological oxidation in a sequencing batch reactor was evaluated in this work. A central composite design approach was used to find the best conditions of temperature, hydrogen peroxide and ferrous ion concentrations that maximize color and dissolved organic carbon removal and increase the biodegradability of the effluent submitted Fentons oxidation. Additional studies on the biological oxidation of the raw and previously treated by Fenton oxidation effluent had been performed up to steady-state. Higher efficiencies were obtained when coupling a pre-oxidation stage with Fentons Reagent to the biological process, but conditions employed in the first process must be carefully selected. In particular, the chemical oxidation was focused in conditions that maximize the increase in the biodegradability, allowing achieving overall removals of 90.2, 97.3 and 96.1 % for DOC, BOD5 and color, respectively.