DYE WASTEWATER TREATMENT: REMOVAL OF REACTIVE DYES USING INORGANIC AND ORGANIC COAGULANTS
Wastewater treatment in textile and dye industry mainly involves treatment of highly colored wastewater containing variety of dyes in different concentrations. The wastewater needs to be treated prior to discharge by effectively removing dye color in order to protect environment and as per the statutory guidelines. Coagulation is the most commonly used method in the treatment of textile wastewater. In the present work, we report experimental work on treatment of synthetic waste containing pure reactive dyes, removal of reactive blue dye, using various commercial coagulants such as alum, polyaluminium chloride (PAC), polydiallyldimethylammonium chloride (poly-DADMAC) and polyamines. The optimum coagulant dose and pH values were determined for these inorganic and organic coagulants by comparing color removal efficiency. It was found that for inorganic coagulant PAC, the color removal was near total at concentration of 200 ppm and above, whereas for alum much higher dosage was needed (> 500 ppm). In both the cases, the color removal efficiency was strongly dependent on pH and best colour removal efficiency was observed only at pH of 5. For polyamine and poly-DADMAC, the optimum coagulant dose was much less as compared to inorganic coagulants. Further, it was found that the color removal efficiency is practically insensitive to pH and the results were good in the pH range of 3 to 10. The results clearly indicate that organic coagulants are more effective in treating wastewaters containing reactive dyes. The study also confirms the strong dependence of color removal efficiency on coagulant type, coagulant dosage and pH apart from its dependence on nature of dye. In an attempt to combine effects of both inorganic and organic coagulants, studies have also been carried out on development of formulations by various combinations of inorganic coagulants such as alum, PAC and organic coagulant-PolyDADMAC. The results of such formulations have been compared with those obtained using individual inorganic and organic coagulants. The results clearly indicate that development of formulations can offer superior solution to coagulation problem as compared to individual coagulants.
V.S. ASHTEKAR , V.M. BHANDARI , S.R. SHIRSATH , P.L.V.N. SAI CHANDRA P.D.JOLHE AND S.A.GHODKE