Colour Removal of Textile Dyeing Effluent Using Low Cost Adsorbents

Abstract

Many industries like dye industries, textile, paper and plastics use dyes in order to colour their products and also consume substantial volumes of water. As a result they generate a considerable amount of coloured wastewater. The presence of small amount of dyes (less than 1 ppm) is highly visible and undesirable.  For the present study the sample effluent is collected from yarn dyeing industry, Coimbatore. The physico-chemical characteristics of the dyeing effluent are carried out according to the standard methods. The characteristics of adsorbents were studied and the selection of natural adsorbents for the colour removal in dyeing effluent is carried out. Experiments were performed to investigate the adsorption capacities of locally available low cost bio-adsorbents like cotton seeds, coconut coir pith, groundnut shell, cotton shell powders to remove colour in a textile industry wastewater. Experimental investigation was carried out to identify the effect of adsorbent dosage, contact time, agitator speed, pH, temperature by using Bach adsorption method. From the experimental investigations, the maximum colour from the textile industry wastewater was obtained at an optimum adsorbent dosage of 300 mg, an optimum contact time of 75 min., an optimum temperature of 330 K and an optimum agitator speed of 600 rpm and optimum pH of 7. Further, from the validation experiments, it was found that the maximum colour removal percentage in textile industry wastewater is about 75.25, 79.9, 86.75 and 81.7 % respectively for Cotton seeds, Coconut coir pith, Groundnut shell, Cotton shell. This result was higher than the results obtained by different process parameters for various bio adsorbents. Finally, from the results of adsorption study, it was concluded that bioadsorbents used as a coagulant for removing the colour from textile industry wastewater especially peanut hulls powder because of its higher adsorptive capacity than other bio-adsorbents used in this study. The experimental data for the adsorption process were well fitted by the Langmuir adsorption isotherm model relative to the fit of the Freundlich adsorption model.