Removal of trivalent chromium from tannery wastewater using solid wastes

The leather tanning industry is one of the important industrial activities in Egypt. However, this industry produces large amounts of wastewater containing trivalent chromium Cr (III) residues that are considered, if not treated, a significant risk to the environment. Although Cr (III) is not as toxic as Cr (VI), there is a high possibility that Cr (III) residues can be oxidized to Cr (VI). Due to this risk, chromium removal from tannery wastewater becomes a vital process. The current study demonstrates the ability of the use of different solid waste materials in the removal of trivalent chromium from tannery wastewater. Four agricultural waste materials and two industrial solid waste materials were tested. The agricultural solid waste materials include rice husk, rice straw, sugarcane bagasse and sawdust; while the industrial waste materials include cement kiln bypass dust and marble powder. The results showed that the cement kiln dust and marble powder can provide the highest removal of chromium from aqueous solution. The results also showed that cement kiln dust can remove more than 99% of the trivalent chromium when the pH of the solution is raised above 8.75.