HYDROMETALLURGICAL METHOD OF SELECTED METALS RECOVERY FROM SEWAGE SLUDGE ASHES

Abstract

With the increasing number of new residents attached to the sewerage system, the amount of generated sewage sludge is systematically growing. In line with the restriction placed on landfill waste with a calorific value above 6 MJ/kg introduced on 1 January 2016, the most popular sewage sludge utilization methods are thermal processes and agricultural use. In recent years, there has been increased interest in using thermal sewage sludge utilization methods. The major problem associated with sludge combustion is the enormous amount of by-products, particularly ashes. Due to the specific characteristics, it is necessary to develop new sewage sludge ashes utilization methods in line with economic, law and environmental requirements. Sewage sludge ashes are rich in valuable metals, particularly in zinc, copper and iron. As utilization methods of sewage sludge ashes do not guarantee the metals recovery until now, metals are lost irretrievably. This article presents hydrometallurgical methods of metals recovery from sewage sludge ashes with the use of acid leaching. The aforementioned propositions are beneficial from the economical and environmental point of view because they prevent valuable metals from waste. Additionally, the whole undertaking could contribute to the popularization of sustainable development.