Comparative studies on adsorptive removal of chromium from contaminated water using different adsorbents

Chromium, especially the hexavalent form, is toxic to humans. Industries like chrome plating, textile, electroplating discharge Cr(VI) in their effiuents. Wastes containing chromium are environmentally persistent and toxic, and cannot be degraded or detoxified biologically. Various techniques developed for the removal of heavy metals include chemical precipitation, ion exchange and adsorption. Activated carbon adsorption systems though widely used are very expensive and the regeneration cost is also very high. Therefore, their use in wastewater treatment may not be economically feasible. There is, therefore, a need to identify and study adsorptive characteristics of low cost alternatives. The present investigation was, therefore, undertaken to select suitable locally and commercially available adsorbents such as activated alumina, ion exchange resin, with special attention to low cost adsorbents like saw dust, treated saw dust and sand, and to carry out a comparative study of their applicability to heavy metal removal. The results of these studies are presented in this paper.