Comparison between biological and chemical–physical treatment for colour removal
The main aim of this research is to compare the efficiency of biological and chemical–physical treatments for the removal of organic azo dyes in the textile wastewater. Regarding the biological reduction of the wastewater colour the anaerobic/aerobic (ANA/AER) sequential step-treatment provides the best reductions in colour and COD. A lab-scale Sequencing Batch Reactor (SBR) fed with synthetic wastewater and mono-azo dye (at the initial concentration of 25 mg/l) was used achieving 84% colour reduction and 82% COD removal. Chemical–physical treatments were performed using the oxidative method with Fenton's reagent and adsorption on the activated carbon achieving respectively colour reduction over 90% (from the initial concentration of 250 mg/l) and 155 mg col/g GAC total adsorption capacity (from the initial concentration of 1 g/l).