Dechlorination and decolorization of chloro-organics in pulp bleach plant E-1 effluents by advanced oxidation processes

Studies were conducted on the composition of chloro-organics in kraft-pulp bleach plant E-1 effluents and their response toward advanced oxidation processes, such as UV-, O2/UV-, O3/UV- and O3–H2O2/UV-photolysis processes with irradiation of 254 nm photons. The studies were extended to ozonation and O3–H2O2 oxidation systems in alkaline aqueous solution. The effects of process variables included initial pH, addition of oxidant to the UV-photolysis system on the decolorization and dechlorination of the chloro-organics the E-1 bleaching effluents were also studied. The decolorization and dechlorination rate constants are increased in the presence of molecular oxygen in the UV-photolysis systems, but are decreased on addition of hydrogen peroxide. The dechlorination rate constants are increased appreciably on oxidation with ozone alone and a combination of ozone and hydrogen peroxide as compared to those of the corresponding UV-photolysis systems under aerial atmosphere