An Investigation on Quality Characterization and Magnitude of Pollution Implications with Textile Dyeing Industries' Effluents using Bleaching Powder

Abstract

This paper describes the outcomes of an investigation on the harmful effects of waste water effluents coming from textile dying industries. A comprehensive study was accomplished through treatment of sample wastes from nine dyeing industries around Gazipur city. Because of high molecular weight and complex chemical structures showing low level of biodegradability, direct deposition of these effluents into sewage networks produce disturbances in treatment processes and exert pollution loads on water bodies. Emphasis was given on the oxidation process for removal of color and other pollution loads. The color removal efficiency was studied by adding different amount of oxidizing agent. Specifically, bleaching powder was used as an oxidizing agent and the parameters considered in this study was pH value, turbidity, total suspended solids (TSS), chemical oxygen demand(COD), and biochemical oxygen demand(BOD). At an optimum level of pH 8.8, the doses of oxidizing agent were determined by batch study. Using the dose of oxidizing agent 500 mg/l, the color removal efficiency of waste water was found to be 90%. It was also seen that the pollution loads (BOD5, COD, and TSS etc.) were reduced to a tolerable limit by using bleaching powder in oxidation process. The color decreased after treatment with bleaching powder consequently increases the total solid in the final effluents. The effects of using various concentrations of bleaching powder on TSS, BOD and COD were studied which have been presented in this paper. The study was focused on the pollution implications of effluents from textile industries around the city, because of the risk of human exposure and environmental degradation by these massive discharge effluents.