Processing of spent tanning and chrome plating solutions for chromium recovery

Use of chromium in metal plating and leather tanning industries generates a lot of effluent containing Cr(III) and Cr(VI). Besides severe water pollution, substantial amount of chromium is lost due to the prevalent practice of removal-disposal technique followed world over. Processes based on recovery and reuse methodology are currently projected as ex¬cellent means of meeting the environmental regulations while producing chromium salts/solutions for recycling. This paper details the composi¬tion, conditions and quantity of spent liquors/effluents generated in elec¬troplating and leather tanning industries and their treatment by removal¬disposal as well as recovery-reuse methods. The approach based on pre¬cipitation, ion exchange and liquid-liquid extraction particularly for chro¬mium recovery is highlighted. The results of solvent extraction with D2EHPA and CYANEX 272 for chromium recovery from spent tanning baths are also summarised.