REMOVAL OF ORGANIC MATTER FROM DISTILLERY EFFLUENT USING ADSORPTION

Abstract

The distillery industries are among the major polluters of the aquatic environment. The waste generated from these industries is highly organic in nature and discharge of these effluents without proper treatment into water bodies can lead to loss of aquatic life due to depletion of dissolved oxygen. Although there have been significant developments in the treatment of distillery spent wash, however, many.of the distilleries are not still able to meet the prescribed limit with the existing treatment facilities. Adsorption is a proven and reliable pollution control technology. Although activated carbon has found wide acceptance by virtue of its high removal capacity and adaptability for a wide range of pollutants, however, because of high cost of activated carbon possibilities of use of various low cost adsorbents like fly ash, wood, peat, sawdust, bagasse pith etc. have been also explored to provide substitute for activated carbon. Present work has been carried out to asses the suitability of bagasse fly ash for removal of COD and colour from distillery and mixed distillery-sugar mill effluent. Few runs have been also conducted with activated carbon for comparison of the adsoption capacity. Effect of various parameters like adsorbent dose, pH, contact time and initial concentration have been investigated in batch system. Kinetics of removal and adsorption isotherms have been also presented. Removal of COD to the extent of 43.48% and 68.43% was achieved by bagasse fly ash and activated carbon from a distillery effluent at initial COD concentration of 1044 mg/l. Higher adsorbent dose was required in case of bagasse fly ash. In case of mixed distillery-sugar mill effluent, 49.29% COD removal was achieved at initial concentration of 840 mg/1 by bagasse fly ash. The equilibrium time was about 6 h. The results indicate that the % COD and TOC removal increases with decrease in initial COD concentration. However, the COD removal per unit weight of adsorbent increased with increasing COD concentration. In case of mixed distillery-sugar mill effluent, COD removal per unit weight of adsorbent was about 19.5 mg/g for baggase fly ash and 20.7 mg/g for activated carbon. Higher removal was achieved in lower pH range.The equilibrium data for removal of COD from distillery and mixed distillery-sugar mill effluent by bagasse fly ash and activated carbon fitted well both Freundlich and Langmuir isotherms. Kinetics of removal follows the first order kinetics in the later part of contact time. The process of removal involves intraparticle diffusion also. Baggase fly ash and activated carbon were also found suitable in removing the colour from distillery effluent and mixed distillery-sugar mill effluent. The results show that bagasse fly ash can be used in the tertiary stage for the removal of organic matter and colour from distillery effluent and mixed distillery-sugar mill effluent.