Advanced oxidation of textile wastewaters

Model dyeing and laundering wastewaters produced during two basic technological operations of the textile industry were subjected to treatment by advanced oxidation processes (AOPs). The following agents were used: ozone (O-3), hydrogen peroxide (H2O2) and UV radiation. They were applied separately and in all possible combinations: O-3 + UV, O-3 + H2O2, UV + H2O2, as well as all three at the same time: O-3 + UV + H2O2. Effluents before and after the treatment were analyzed according to requirements of the Polish Standards that included pH, color threshold, COD and concentration of anionic and non-ionic surfactants. Ozonation was carried out in a lab-scale bubble column reactor with a centrally located UV burner. The most effective version of AOPs proved to be the simultaneous use of all three agents. In the case of such treatment of dyeing wastewaters nearly complete discoloration and full decomposition of surface-active substances were obtained at 80% reduction of COD. A similar tendency was observed in the case of laundering wastewater, though in that case the results were slightly worse, which may be explained by much higher initial concentrations of the pollutants. Good treatment effects have also been obtained in combined treatment by simultaneous use of hydrogen peroxide and ozone.