Decolorizing dye wastewater with low temperature catalytic oxidation

Abstract

Novel oxidation technology to decolorize dye wastewater was discussed and the feasibility of color removal with Fe/MgO catalyst fluidizing ina reactor under continuous flow was demonstrated at room temperature. In batch tests, the oxidation reaction of reactive and disperse dye with an oxidizing agent, hydrogen peroxide, in the presence of Fe/MgO catalyst was performed. Through the catalytic oxidation, dyes were oxidized to molecules with lower molecular weight and then mineralized based on TOC analysis. The influence of hydrogen peroxide and catalyst dosage on the catalytic oxidation rate was verified. The catalytic oxidation rate increased with increasing hydrogen peroxide and catalyst dosage. Fe/MgO catalyst fluidizing in the reactor operated at room temperature was tested to decolorize the wastewater from a dye manufacturing industry. In the fluidized bed reactor, the wastewater was completely decolorized and about 30% of COD removal was obtained during 30 days of operation. Organic matters were degraded and part of them mineralized by the catalytic oxidation. BOD/COD ratio of the effluent from the fluidized bed reactor was increased compared to that of the influent. After 30 days of operation, the effluent from the fluidized bed reactor started becoming yellowish. COD and residual hydrogen peroxide concentration in the effluent started to increase due to the catalyst losing its activity; (C) 1999 IAWQ Published by Elsevier Science Ltd. All rights reserved.