Stabilization/solidification of zinc containing sludge using Portland cement

Abstract

Stabilization/Solidification process using Portland cement was applied for the treatment of sludge from hot-dip galvanization process. It is a process aimed at protecting and improving the quality of steel parts against the corrosion and oxidation caused by the humidity. Ordinary Portland cement was chosen as a binder for its affordability as a one of the cheapest type of binder and well known for its usability for hazardous waste treatment. Effectiveness of the process was evaluated using leaching tests according to both the EN 12457-4 standard and the Toxicity Characteristic Leaching Procedure. The effect of the mixture composition on the process was analysed in terms of the extract toxicity and ability to retain pollutants in the concrete matrix. Furthermore, the obtained data were evaluated using statistical analysis, namely, multi-level factorial design of experiment. This paper deals with the waste from the pretreatment of steel pieces by degreasing and chemical cleaning the surface before the hot-dip galvanization process. This waste does not meet the regulatory levels of the pollutant leaching and thus its treatment is required before land disposal. The aim of this study was to stabilize and solidify this toxic waste and thus fulfil the limit values required for land disposal.