Dyestuff wastewater treatment by combined SDS-CuO/TiO2 photocatalysis and sequencing batch reactor

Combined technology of SDS-CuO/TiO2 photocatalysis and sequencing batch reactor ( SBR) were applied to treating dyestuff wastewater. Photocatalysis was carried out in a spiral up-flow type reactor as pre-treatment. SDS-CuO/TiO2 photocatalyst was prepared by modification of nano-TiO2 using CuO and sodium dodecyl sulfate ( SDS). Results show that the SDS-CuO/TiO2 photocatalyst contains two kinds of crystals, including TiO2 and CuO. The band gap of this photocatalyst is 1.56 eV, indicating that it can be excited by visible light (lambda<794.87 nm). And characterization also shows that there are alkyl groups on its surface. It takes 40 min to improve the biodegradability of dyestuff wastewater. Five-day biochemical oxygen demand ( BOD5) and dehydrogenase activity (DHA) of wastewater reach the maximum value when dissolved oxygen is higher than 2.97 mg/L. SBR reactor was used to treat this biodegradability improved wastewater. Chemical oxygen demand ( COD) and colority decline to 72 mg/L and 20 times, respectively, when the sludge loading is 0.179 kg(COD)/[kg( MLSS).d], dissolved oxygen is 4.09 mg/L and aeration time is 10 h.