Reactive dye effluent treatment using a mixture of sugarcane bagasse and water hyacinth

Abstract

Water pollution remains a major problem in developing countries. Textile industries contribute to this problem by producing large amounts of wastewater during dyeing and finishing processes. The dye that remains in the wastewater is a disturbance to the ecological system besides being a health hazard. Therefore, the main objective of this project was to develop an adsorbent material from a blend of sugarcane bagasse and water hyacinth for removal of reactive red 198 dye, commonly used on cellulosic fibers, from textile effluent. The specific objectives of the study were to develop adsorbent materials from sugarcane bagasse and water hyacinth through chemical modification, to blend modified sugarcane bagasse and water hyacinth at different ratios and analyze their dye adsorption at varied conditions (dye concentrations, particle sizes) and to optimize dye adsorption of the blend by varying adsorbent dosage, blend ratio and initial dye concentration. Sugarcane bagasse treated with 0.1M hydrochloric acid and water hyacinth treated with 0.1M sodium hydroxide were blended together and used to treat wastewater containing reactive red 198 dyes. Batch experiments were carried out varying the initial dye concentration from 5 mg/l to 50 mg/l, adsorbent particle sizes from 280 um to 2000 um and blend ratios of 0:100, 25:75, 50:50 and 100:0. The absorbance of the samples was measured using UV Vis spectrophotometer and percentage dye removal determined. Minitab statistical tool was used in experimental optimization based on the rotatable central composite design. A full quadratic regression equation that related the variables and the response was developed. A two-way interaction of the regression model was investigated. From the regression model, initial dye concentration and blend ratio had significant effect on adsorption since P-value was less than 0.005. Adsorption of reactive red 198 dye was optimal at initial dye concentration of 50.23 mg/l, particle size of 745.87 um and at a blend ratio of 100:0. At these optimum conditions, the dye removal percentage was found to be 89%, with the chemical oxygen demand (COD) reduction of 95%. From the current result, it was concluded that chemically modified sugarcane bagasse could serve as adsorbent materials for removing reactive red 198 dyes from textile wastewater. Treatment of the adsorbents enhances their dye adsorption compared to non-modified adsorbents. Adsorption process may therefore be employed as a clean technology in wastewater treatment. However, the two adsorbents should be used separately to obtain better results unless an optimal blend is established.