Treatment of synthetic dye containing textile raw wastewater effluent using UV/Chlorine/Br photolysis process followed by activated carbon adsorption

Abstract

This study investigated the efficiency and feasibility of ultraviolet (UV)-assisted photolysis of synthetic dye containing textile raw wastewater effluent. For a said purpose, in-house developed UV/Chlorine/Br process was followed in the presence of activated carbon (AC) which additionally facilitate the dye adsorption. In UV/Chlorine process Cl-center dot, Cl-2(center dot-), and HO center dot are generated in the solution and destroyed compounds that cannot be oxidized by the conventional oxidant. In this process, free bromine is formed and photolyzed by UV radiation and generate Br-center dot and Br-2(center dot-) that can enhance the rate of pollutant degradation. In the present study, the dye removal efficiency was contributed by dark bromide (7.18), UV irradiation (26.8), dark chlorination (78.67), and UV/Chlorine/Br (87.01), respectively. With increasing pH from 3.0 to 8.30, the dye removal efficiency was enhanced but decreased by further increasing pH values. In addition, magnetized activated carbon from pomegranate husk using dual-stage chemical activation was used for post-adsorption of the residual dye and its degradation byproducts. The adsorption of the dye residues by AC followed the second-order kinetics with the rate constant of 1.7 x 10(-3). The phytotoxicity of the treated textile wastewater by UV irradiation, dark chlorination, and UV/Chlorine/ Br was assessed by seed germination of Lepidium sativum seeds. The highest inhibition effect on seed germination was related to treated wastewater by UV irradiation (more than 90 inhibition) that alleviated to less than 10 when this effluent diluted to 5 v/v. The highest germination was observed when the seeds were irrigated by the effluent of the UV/Chlorine/Br process. The significant reduction in the toxicity of the treated wastewater revealed that the UV/Chlorine/Br process has a considerable potential to effectively detoxify textile wastewater.