The use of extraction methods to assess the immobilization of metals in hardening slurries

Abstract

In Poland, in recent years, there has been a rapid accumulation of sewage sludge – a by-product in the treatment of urban wastewater. This has come about as a result of infrastructure renewal, specifically, the construction of modern sewage treatment plants. The more stringent regulations and strategic goals adopted for modern sewage management have necessitated the application of modern engineering methodology for the disposal of sewage sludge. One approach is incineration. As a consequence, the amount of fly ash resulting from the thermal treatment of municipal sewage sludge has grown significantly. Hence, intensive work is in progress for environmentally safe management of this type of waste. The aim of the experiment was to evaluate the possibility of using the fly ash that results from municipal sewage sludge thermal treatment (SSTT) as an additive to hardening slurries. The article presents the technological and functional parameters of hardening slurries with an addition of fly ash obtained by SSTT. Moreover, the usefulness of these slurries is analyzed on the basis of their basic properties, i.e., density, contractual viscosity, water separation, structural strength, volumetric density, hydraulic conductivity, compressive and tensile strength. The research on technological and functional properties was carried out, the aim of which was to determine the practical usefulness of the hardening slurries used in the experiment. Subsequently, leaching tests were performed for heavy metals in the components, the structure of the hardening slurries. An experiment showed leaching of hazardous compounds at a level allowing their practical application. The article presents the potential uses of fly ash from SSTT in hardening slurry technology.

Keywords

• hardening slurry
• cut-off walls
• sewage sludge thermal treatment
• immobilization of metals