Decolorizing of lignin wastewater using the photochemical UV/TiO 2 process

Abstract

Studies on applying the photochemical UV/TiO 2 oxidation process to treat the lignin-containing wastewater for dissolved organic carbon (DOC), color and reducing A 254 (the absorption at the wavelength of 254 nm) have been carried out. The data obtained in this study demonstrate that the UV/TiO 2 process is effective in oxidizing the lignin thus reducing the color and DOC of the wastewater treated. The combined UV/TiO 2 treatment can achieve better removal of DOC and color than the UV treatment alone. Color removal, based on American Dye Manufacture Index (ADMI) measurement, is greater than 99% if the pH is maintained at 3.0 with the addition of 1 g l −1 TiO 2. When 10 g l −1 TiO 2 is applied, the oxidation reduction potential (ORP) value is reached to result in an 88% removal of both DOC and color. A model was developed based on the variation of ORP during the photochemical reaction to simulate the decoloring process. The proposed model can be used to predict the color removal efficiency of the UV/TiO 2 process.