Techno-Economic Evaluation of Chromium Recovery Pilot Plant Installed at Kasur Tanneries Complex, Pakistan

Chromium metal is widely used as a tanning agent worldwide. The process called chrome-tanning is accomplished in three steps: Pickling, Tanning and Basification1 (Pakistan Tanners Association). Chromium sulfate is the most widely used chemical in this process. Approximately, 60–70 percent of chromium sulfate applied is taken up by the hides and skins, while its 30 to 40 percent remains un-used and is discharged as a component of wastewater into natural water bodies such as rivers, streams, etc., which has adverse environmental impacts on living organisms particularly to humans and animals [Weitz and Luxenberg (n.d.)], and water animals such as fish [Eisler (1986)]. The diseases especially encountered in humans, are of nervous disorders. The pollution from tanneries effluent particularly their chromium component has formed the basis that many developed countries have banned tanning on their soils. Chrome tanned leather, being the need of people all over the world, has the edge that its manufacture cannot be stopped. This has given some economic advantage to some developing countries including Pakistan to manufacture leather and export it to the developed countries. To sustain, different methods have been developed to recover chromium from the tannery effluents before their drainage in the natural water bodies. A few examples of these methods are High Chrome Exhaustion, Direct Recycling of the Spent Tanning Float and Chrome Recovery and Reuse [Arrafay Labs (2003)].