Abstract: Textile dyeing industries are one of the major polluting industries that generate highly coloured wastewater containing exhausted dyestuffs. These unfixed dyes are in general refractory in nature and difficult to treat effectively by the existing conventional methods. In the present work, decolourisation and degradation of six real textile dyeing wastewater were experimented using fixed catalyst mode Photocatalytic-Ozonation (UV/TiO2/O3) processes. The experiments were carried out in a reactor of 15 L capacity. All the wastewaters were highly coloured with Chemical Oxygen Demand (COD) ranging from 760 to 2080 mg/L and Total Organic Carbon (TOC) from 210 to 458 mg/L. The low biodegradability ratio indicated that the wastewater samples were less biodegradable. The coupled photocatalytic-ozonation yielded complete colour removal with 64 % COD removal after 30 minutes of treatment. It was also observed that the maximum oxidation and biodegradability improvement occurred in coupled photocatalytic-ozonation process. The reaction kinetics followed pseudo-first order. The immobilized catalyst system developed was found to be stable for 10 consecutive runs.

Keywords: Photocatalytic-Ozonation, AOP, fixed-catalyst, biodegradability.