title: Stabilization of heavy metals in lightweight aggregate made from sewage sludge and river sediment.
abstract: The primary goal of this research is to investigate the stabilization of heavy metals in lightweight aggregate (LWA) made from sewage sludge and river sediment. The effects of the sintering temperature, the (Fe₂O₃+CaO+MgO)/(SiO₂+Al₂O₃) ratio (K ratio), SiO₂/Al₂O₃ and Fe₂O₃/CaO/MgO (at fixed K ratio), pH, and oxidative conditions on the stabilization of heavy metals were studied. Sintering at temperatures above 1100 °C effectively binds Cd, Cr, Cu and Pb in the LWA, because the stable forms of the heavy metals are strongly bound to the aluminosilicate or silicate frameworks. Minimum leachabilities of Cd, Cr, Cu and Pb were obtained at K ratios between 0.175 and 0.2. When the LWA was subjected to rigorous leaching conditions, the heavy metals remained in the solid even when the LWA bulk structure was broken. LWA made with sewage sludge and river sediment can therefore be used as an environmentally safe material for civil engineering and other construction applications.
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin, 150090, China. xgr@hit.edu.cn
authors.forename: Guoren
authors.initials: G
authors.lastname: Xu
authors.forename: Mingwei
authors.initials: M
authors.lastname: Liu
authors.forename: Guibai
authors.initials: G
authors.lastname: Li
mesh_terms: D003247:Conservation of Natural Resources; D003252:Construction Materials / Q000032:analysis*; D004785:Environmental Pollutants / Q000032:analysis; D019015:Geologic Sediments / Q000737:chemistry*; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste / Q000032:analysis; D008422:Materials Testing; D019216:Metals, Heavy / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D045483:Rivers; D012722:Sewage / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D013696:Temperature
chemical_list: D004785:Environmental Pollutants; D007220:Industrial Waste; D019216:Metals, Heavy; D012722:Sewage; D017640:Silicates; D006861:Hydrogen Peroxide; D010100:Oxygen
keywords: Heavy metals; Leachability; Lightweight aggregate; River sediment; Sewage sludge