Exploring the potential of incinerated MSW ash for landfill liner applications

Rapid urbanisation and population growth have resulted in the generation of 2.01 billion tonnes of municipal solid waste (MSW) globally each day. Incineration is a widely used method to reduce the mass and volume of this waste, however it produces substantial amount of residual ash that requires further treatment before it can be safely used in geotechnical engineering applications. The large volume of municipal solid waste incineration (MSWI) ash generated poses significant challenges, occupies valuable landfill space, and complicates waste management efforts. This study investigates the reuse potential of MSWI ash (both bottom ash and fly ash) as a sustainable landfill liner material. A comprehensive analysis of the chemical, physical, and geotechnical properties of MSWI ash was conducted, revealing typical ranges such as maximum dry density (MDD) of 10.8–17.6 kN/m3, optimum moisture content (OMC) of 10.8%–45.7%, permeability ranging from 10−9 to 10−3m/s, friction angle from 20.8° to 54.5°, and cohesion values of 0–52.4 kN/m2. The presence of minerals like calcite and quartz contributes significantly to strength characteristics. To meet the low permeability requirements for landfill liners, MSWI ash has been blended with bentonite, which enhances its barrier performance. Leaching studies highlight the influence of pH on the release of heavy metals, emphasising the need for stabilisation techniques. Various stabilisation methods have been demonstrated to effectively immobilise hazardous constituents including heavy metals and dioxins. The findings suggest that MSWI ash can play a key role in promoting sustainable waste management by immobilising contaminants and mitigating the environmental and health risks associated with its disposal. By integrating MSWI ash into engineering applications, this sustainable approach not only reduces the environmental footprint of waste management, but also offers innovative solutions for the reuse of industrial by-products.