title: Heavy metal removal mechanisms of sorptive filter materials for road runoff treatment and remobilization under de-icing salt applications.
abstract: The objective of this research study was to elucidate the removal and remobilization behaviors of five heavy metals (i.e., Cd, Cu, Ni, Pb, and Zn) that had been fixed onto sorptive filter materials used in decentralized stormwater treatment systems receiving traffic area runoff. Six filter materials (i.e., granular activated carbon, a mixture of granular activated alumina and porous concrete, granular activated lignite, half-burnt dolomite, and two granular ferric hydroxides) were evaluated in column experiments. First, a simultaneous preloading with the heavy metals was performed for each filter material. Subsequently, the remobilization effect was tested by three de-icing salt experiments in duplicate using pure NaCl, a mixture of NaCl and CaCl2, and a mixture of NaCl and MgCl2. Three layers of each column were separated to specify the attenuation of heavy metals as a function of depth. Cu and Pb were retained best by most of the selected filter materials, and Cu was often released the least of all metals by the three de-icing salts. The mixture of NaCl and CaCl2 resulted in a stronger effect upon remobilization than the other two de-icing salts. For the material with the highest retention, the effect of the preloading level upon remobilization was measured. The removal mechanisms of all filter materials were determined by advanced laboratory methods. For example, the different intrusions of heavy metals into the particles were determined. Findings of this study can result in improved filter materials used in decentralized stormwater treatment systems.
authors.affiliation: Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Huber
authors.affiliation: cbm-Centre for Building Materials, Technical University of Munich, Baumbachstraße 7, 81245 Munich, Germany.
authors.forename: Harald
authors.initials: H
authors.lastname: Hilbig
authors.affiliation: Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany.
authors.forename: Sophia C
authors.initials: SC
authors.lastname: Badenberg
authors.affiliation: Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany.
authors.forename: Julius
authors.initials: J
authors.lastname: Fassnacht
authors.affiliation: Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany.
authors.forename: Jörg E
authors.initials: JE
authors.lastname: Drewes
authors.affiliation: Chair of Urban Water Systems Engineering, Technical University of Munich, Am Coulombwall 3, 85748 Garching, Germany. Electronic address: b.helmreich@tum.de.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Helmreich
mesh_terms: D019216:Metals, Heavy; D012965:Sodium Chloride; D017673:Sodium Chloride, Dietary; D014874:Water Pollutants, Chemical; D018508:Water Purification
chemical_list: D019216:Metals, Heavy; D017673:Sodium Chloride, Dietary; D014874:Water Pollutants, Chemical; D012965:Sodium Chloride
keywords: De-icing salts; Decentralized system; Filter material; Road maintenance; Stormwater treatment; Winter service