Possible Applications of Hardening Slurries with Fly Ash from Thermal Treatment of Municipal Sewage Sludge in Environmental Protection Structures

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. This type of hardening slurry with various types of additives, e.g. coal combustion products, is used in the construction of cut-off walls in hydraulic structures.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 analysed 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 mandated requirements for slurries employed in the construction of cut-off walls in flood embankments are listed as a usefulness criteria.The article presents the potential uses of fly ash from SSTT in hardening slurry technology. It also suggests directions for further research to fully identify other potential uses of this by-product in this field.

Immobilization of selected heavy metals from fly ash from thermal treatment of municipal sewage sludge in hardening slurries

“…The ash generated as a result of sewage sludge incineration is characterised by, among others, a high water demand, low hydraulic and pozzolanic activities [2,3], and a significant phosphorus content [4]. In addition, as a consequence of the municipal sewage sludge incineration and the related concentration of components, the ashes show an increased content of some heavy metals [5].…”

“…One of the ways of managing the growing amounts of fly ashes from thermal treatment of municipal sewage sludge is their use in hardening slurries [2], in which other combustion byproducts are successfully used [6]. The nature and use of hardening slurries (e.g.…”

The Release of Heavy Metals from Hardening Slurries with Addition of Selected Combustion By-products

“…The data presented in the literature [1,3] clearly indicate a decrease in the amount of sludge stored in landfills (from about 16% in 2008, to about 5% in 2014) and an increase in the amount of sludge processed thermally (from about 1% in 2008, to about 15% in 2014). The above trends also match the goals set by the municipal sewage sludge management directives [4].…”

Hardening Slurries with Fluidized-Bed Combustion By-Products and Their Potential Significance in Terms of Circular Economy

“…The technological properties based on [3,4,7,8] and their significance are as follows (the values in parentheses are typical for slurries used in Poland, based on [9]):…”