Enhancing the reuse of treated effluent by photocatalytic process

Studies on applying the UV/TiO₂ photocatalytic process to reduce color and trace organics remained in the treated effluent have been carried out using pellet form photocatalyst in a static photocatalytic decolorization system. The effluent was characterized by general parameters such as color, A₂₅₄ (the organics absorption at the wavelength of 254 nm), total organic carbon (TOC), chemical oxygen demand (COD) and by the analysis of organic compounds using high performance size exclusion chromatography (HPSEC). The effects of catalyst amount, initial volume of effluent, UV intensity, light source, as well as catalyst regeneration (reuse) on the process efficiency were investigated. The data obtained in this study demonstrate that the UV/TiO ₂ photocatalytic process is effective in reducing the organic matters including color causing compounds in the treated effluent. Color removal is great than 80% after 2 h of reaction with the dosage of 20 g TiO₂. The HPSEC profiles reveal that only very small amount of organic matters remained in the treated samples, suggesting an extensive mineralization which was corroborated by 77% A₂₅₄, 54 % COD and 52% TOC removals. The catalyst amount and initial volume of effluent treated have a great impact on the process efficiency. The effects of UV light source and intensity, however, are relatively small in this study. The activity of used photocatalysts could be regenerated to a full extent by UV irradiation.