Inertisation of galvanic sludge with calcium oxide, activated carbon, and phosphoric acid

Abstract

In this study we compared three methods for the treatment of electroplating sludge highly loaded with zinc and iron: (1) calcium oxide-based solidifi cation/stabilisation; (2) conversion into inert material by adsorption of organic and inorganic pollutants onto activated carbon; and (3) conversion of mobile waste components into insoluble phosphates. All three methods proved highly effi cient in the conversion of hazardous waste into inert material. Under optimum treatment conditions zinc concentration in the leachate of solidifi ed waste was reduced by 99.7 % compared to untreated sludge. Zinc retention effi ciency in the waste treated with activated carbon and phosphoric acid was 99.9 % and 98.7 %, respectively. The advantages of electroplating sludge treatment with activated carbon over the other two methods are high sorption capacity, insignifi cant pH and volume changes of the sludge, and simple use.