Abstract:
Metals to be coated requires pre- treatment to remove rust or scale, impurities and inorganic contaminants. The pickling process generates a considerable quantity of spent pickle liquor (SPL) containing the dissolved metal salts of Iron, Chromium, Copper, Nickel and Zinc as well as residual free acid. The waste generated by metal pickling and electroplating industries identified as hazardous solid waste as per Indian Standards and USEPA Standards. In this paper we have discuss about the conventional treatment method of SPL, Safe disposal of sludge, utilization of sludge, various types of acid regeneration methods and metals recovery from it .