DECOLORISATION OF PULP & PAPER MILL EFFLUENT

Abstract

Paper plays a vital role in cultural development of human being. The increase in literacy, growing trends of higher ratio of professional and technical jobs in work force and growing economic activity are bound to increase the consumption of paper. Consumption of paper in the countries like India is increasing rapidly. The paper industry consumes large amount of water and discharges almost same amount of wastewater and is often accused of discharging colored effluent creating aesthetic and chemical pollution. The color in the wastewater is mainly due to dyes. A wide variety of colored paper is made using various types of dyes. There is some difficulty in removing dyes from the effluents since the dyes are stable to light and heat and are biologically non-degradable. Among the several treatment processes, adsorption still continues to be most widely used process. Adsorption by activated carbon, is the most widely used process in wastewater treatment. In view of high cost and tedious procedure for the preparation and regeneration of activated carbon there is continuing search for the low cost adsorbents. In present investigations, the waste slurry (carbonaceous material) generated in fertilizer plants and bagasse fly ash generated in sugar mills, activated carbon laboratory grade were used as adsorbents for the removal of different dyes. Congo Red, Orange-G, Auramine, Brilliant Green, Methyl Violet, Rhodamine—B dyes that are commonly used in paper mills, were selected as adsorbates. In batch studies, the adsorption isotherms have been used to know the effectiveness of adsorbents. TheLangmuir and Freundlich isotherms have fitted best for the process and effect of contact time is also observed. Column studies of different dyes were conducted and break-through curves are presented. By comparing adsorption capacities of carbon slurry, activated carbon and bagasse fly ash it is observed that the adsorption capacity of carbon slurry is approximately equal to activated carbon and more than bagasse fly ash.