title: Arsenic, chromium and mercury removal using mussel shell ash or a sludge/ashes waste mixture.
abstract: Different batches of valued mussel shell and waste mussel shell ash are characterised. Shell ash has pH > 12 and high electrical conductivities (between 16.01 and 27.27 dS m(-1)), while calcined shell shows pH values up to 10.7 and electrical conductivities between 1.19 and 3.55 dS m(-1). X-ray fluorescence, nitric acid digestion and water extractions show higher concentrations in shell ash for most parameters. Calcite is the dominant crystalline compound in this ash (95.6%), followed by aragonite. Adsorption/desorption trials were performed for mussel shell ash and for a waste mixture including shell ash, sewage sludge and wood ash, showing the following percentage adsorptions: Hg(II) >94%, As(V) >96% and Cr(VI) between 11 and 30% for shell ash; Hg(II) >98%, As(V) >88% and Cr(VI) between 30 and 88% for the waste mixture. Hg and As desorption was <5% for both shell ash and the waste mixture, while Cr desorption was between 92 and 45% for shell ash, and between 19 and 0% for the mixture. In view of that, mussel shell ash and the mixture including shell ash, sewage sludge and wood ash could be useful for Hg(II) and As(V) removal.
authors.affiliation: Departamento de Edafoloxía e Química Agrícola, Escola Politécnica Superior, University of Santiago de Compostela, Campus univ. s/n, 27002 Lugo, Spain.
authors.forename: Natalia
authors.initials: N
authors.lastname: Seco-Reigosa
authors.forename: Susana
authors.initials: S
authors.lastname: Peña-Rodríguez
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Nóvoa-Muñoz
authors.forename: Manuel
authors.initials: M
authors.lastname: Arias-Estévez
authors.forename: María J
authors.initials: MJ
authors.lastname: Fernández-Sanjurjo
authors.forename: Esperanza
authors.initials: E
authors.lastname: Alvarez-Rodríguez
authors.forename: Avelino
authors.initials: A
authors.lastname: Núñez-Delgado
mesh_terms: D000327:Adsorption; D060105:Animal Shells / Q000737:chemistry*; D000818:Animals; D001151:Arsenic / Q000737:chemistry; D002857:Chromium / Q000737:chemistry; D004785:Environmental Pollutants / Q000737:chemistry*; D007220:Industrial Waste / Q000032:analysis*; D008628:Mercury / Q000737:chemistry; D049878:Mytilus; D012722:Sewage / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D018505:Waste Management / Q000379:methods*; D014934:Wood / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D004785:Environmental Pollutants; D007220:Industrial Waste; D012722:Sewage; D002857:Chromium; D008628:Mercury; D001151:Arsenic