DECOLORIZATION OF INDUSTRIAL DYEING WASTEWATER BY COAGULATION WITH ALUM, POLY ALUMINUM CHLORIDE (PAC), POLYELECTROLYTE AND OXIDATION USING CHLORINE
Coagulation and flocculation is a widely practiced method for removing color from textile and tannery wastewaters. The aim of this research was to test the feasibility of using various coagulants and oxidants for treating textile wastewater. The effect of various operating variables like coagulant dose, pH, and reaction time were measured. Poly aluminum chloride (PAC), Alum and Chlorine were used for color removal. The collected wastewater had an average color of 12355 Pt-Co. PAC showed better color removal compared to Alum at similar doses. Also PAC was efficient over a wider pH range (3-11) compared to Alum. PAC also creates stronger flocs which settle faster than Alum. Up to 99% color removal could be achieved using a 2000 mg/l dose of PAC. Poly electrolyte enhances the color removal efficiency but also increases the Electrical Conductivity (EC) a lot. Oxidization by chlorine removes color, and combination of PAC with chlorine reveals great opportunities. Chlorine removes color but enhances the EC less compared to other chemicals. Mixing sequence of chlorine and PAC affects the color removal efficiency, and better color removal is possible with increased contact time with chlorine by successive mixing of chlorine and PAC with an interval of 15 minutes. Optimum dose was selected by selecting dose within the range of high efficiency. 99% color removal was achieved using a 200 mg/l dose of PAC and a 150 mg/l dose of chlorine.
MUHAMMAD MOHSIN MEHEDI