title: A safer disposal of hazardous phosphate coating sludge by formation of an amorphous calcium phosphate matrix.
abstract: Phosphate coating hazardous wastes originated from the automotive industry were efficiently encapsulated by an acid-base reaction between phosphates present in the sludge and calcium aluminate cement, yielding very inert and stable monolithic blocks of amorphous calcium phosphate (ACP). Two different compositions of industrial sludge were characterized and loaded in ratios ranging from 10 to 50 wt.%. Setting times and compressive strengths were recorded to establish the feasibility of this method to achieve a good handling and a safe landfilling of these samples. Short solidification periods were found and leaching tests showed an excellent retention for toxic metals (Zn, Ni, Cu, Cr and Mn) and for organic matter. Retentions over 99.9% for Zn and Mn were observed even for loadings as high as 50 wt.% of the wastes. The formation of ACP phase of low porosity and high stability accounted for the effective immobilization of the hazardous components of the wastes.
authors.affiliation: MIMED Research Group, Department of Chemistry and Soil Sciences, School of Sciences, University of Navarra, Irunlarrea, 1, 31008 Pamplona, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Navarro-Blasco
authors.affiliation: MIMED Research Group, Department of Chemistry and Soil Sciences, School of Sciences, University of Navarra, Irunlarrea, 1, 31008 Pamplona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Duran
authors.affiliation: MIMED Research Group, Department of Chemistry and Soil Sciences, School of Sciences, University of Navarra, Irunlarrea, 1, 31008 Pamplona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Pérez-Nicolás
authors.affiliation: MIMED Research Group, Department of Chemistry and Soil Sciences, School of Sciences, University of Navarra, Irunlarrea, 1, 31008 Pamplona, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Fernández
authors.affiliation: MIMED Research Group, Department of Chemistry and Soil Sciences, School of Sciences, University of Navarra, Irunlarrea, 1, 31008 Pamplona, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Sirera
authors.affiliation: MIMED Research Group, Department of Chemistry and Soil Sciences, School of Sciences, University of Navarra, Irunlarrea, 1, 31008 Pamplona, Spain. Electronic address: jalvarez@unav.es.
authors.forename: J I
authors.initials: JI
authors.lastname: Alvarez
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry; D017610:Calcium Compounds / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry*; D006256:Hazardous Waste; D007220:Industrial Waste; D008670:Metals / Q000032:analysis*; D010710:Phosphates / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry*; D064091:Waste Disposal Facilities; D018505:Waste Management / Q000379:methods*
chemical_list: D017607:Aluminum Compounds; D017610:Calcium Compounds; D002130:Calcium Phosphates; D006256:Hazardous Waste; D007220:Industrial Waste; D008670:Metals; D010710:Phosphates; D012722:Sewage; C519480:amorphous calcium phosphate; C035219:calcium aluminate
keywords: Calcium aluminate cement; Heavy metals; Leaching; Solidification/stabilization; Waste management; Zinc