Valorization of industrial wastes as alternative liner materials: toxicity assessment

Abstract The use of alternative materials for engineering barriers based on industrial waste has gained attention due to disposal concerns and excessive consumption of natural resource consumption. However, waste-based toxicity regarding leaching behavior must be assessed prior to reutilization. This study investigates the feasibility of using water treatment sludge (WTS), vegetal biomass ash (VBA), granitic mining waste (GMW), and blast furnace slag (BFS), mixed in different ratios with a natural soil as alternative materials for liners. The assessment was carried out following microstructure and chemical through energy dispersive spectrometry attached to scanning electron microscopy (SEM-EDS), mineralogy from X-ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and toxicity characteristic leaching procedure (TCPL). Results revealed pH values ranging from 5.55 for WTS to 11.1 for BFS, influenced their interactions in liners, specifically, GMW closely resembles local bedrock and poses minimal contamination risk; BFS, rich in iron and calcium oxides, shows potential cementitious properties but requires assessment for expansive behavior; VBA, transformed through incineration, exhibits pozzolanic potential due to high Si, Al, and Fe content; and WTS, mainly amorphous, reduces mixture density but requires further pozzolanic activity analysis. Regarding chemical stability and leaching potential, WTS’ alumina and silica potentially adsorb, bind and mobilize certain metals, GMW’s quartz and feldspar results in low metal mobility, and VBA and BFS alkalinity can encapsulate pollutants via hydration products. Across all materials, TCLP results were below regulatory limits. This research highlights the dual benefits of reducing industrial waste disposal and developing sustainable geomaterials for geotechnical applications.