RECYCLING OF SPENT SOLUTIONS OF TANNERY LIQUID WASTE

Abstract

Over the years, treatment of tannery waste-Water put a considerable burden on the total cost of production, be it pickled, in wet-blue, crust or finished leather. After 1980 a very stringent regulation has been imposed on the quality and purity of the waste waters that go to the drain. The high amount of money charged for effluent tannery waste-water, lead most of the tanneries to close down with increasingly stringent environmental requirements, it has become necessary to reduce the pollution load in waste-water to a minimum. This has been done by treating tannery waste-water biologically with expensive undertaking as no income or revenue is obtained at the end. For these reasons, recycling of spent solutions from soaking through retannage has been applied in this work with a considerable saving of 40% and 75%, chemicals and water, as well as protection of the environment from these polluting chemicals as compared with the standard process without recycling. The treatment of tannery waste-water is done through addition of the required materials to each process and recycling of the spent solution. After the process is completed the pelts are unloaded, the once-used solution is topped up with the required make-up and reused. The process of recycling is repeated seven times from one batch to another. By this method of recycling there will be saving in water, chemicals and protection of the environment. The leather processed using recycled solution adjusted with a make-up showed comparatively good physical and chemical properties. The tensile strength obtained is acceptable, and the elongation at grain crack is very good, the load at grain burst is also 200kg/cm2. The elongation at grain crack is equal to the tensile strength. In conclusion it is recommended to apply recycling of tannery used solutions from soaking through retanning processes. The total cost will be reduced, then there will be saving in chemicals and clean environment.