Notice of Retraction: Catalytic Ozonation of Paper Mill Effluent by Activated Carbon (AC), TiO2/AC, Al2O3 and TiO2/Al2O3

Although traditional biological treatments effectively reduce the pollution level of paper mill effluent, biologically treated effluent usually can not meet the effluent emission standard. The objective of this study is to investigate the treatment efficiency of the biologically treated effluent by single ozonation and ozonation in the presence of activated carbon (AC), TiO2/AC, Al2O3 and TiO2/Al2O3 catalysts. Results showed that treatment efficiency was enhanced by the simultaneous use of ozone and the catalysts, evaluated as chemical oxygen demand (COD) and color removal rates. The COD and color removal rates reached 51% and 91% for ozonation with TiO2/AC, 55% and 92% for ozonation with TiO2/Al2O3 catalyst, compared with 37% and 83% for single ozonation. It was also found that BOD5/COD effectively increased after ozonation and catalytic ozonation, indicating obvious enhancement of the biodegradability of the effluent.