title: Laboratory and pilot scale soil washing of PAH and arsenic from a wood preservation site: changes in concentration and toxicity.
abstract: Soil washing of a soil with a mixture of both polycyclic aromatic hydrocarbons (PAH) and As was evaluated in laboratory and pilot scale, utilizing both single and mixtures of different additives. The highest level of decontamination was achieved with a combination of 0.213 M of the chelating agent MGDA and 3.2 x CMC* of a non-ionic, alkyl glucoside surfactant at pH 12 (Ca(OH)(2)). This combination managed to reach Swedish threshold values within 1 0 min of treatment when performed at elevated temperature (50 degrees C), with initial contaminant concentrations of As=105+/-4 mg/kg and US-EPA PAH(16)=46.0+/-2.3mg/kg. The main mechanisms behind the removal were the pH effect for As and a combination of SOM ionization as a result of high pH and micellar solubilization for PAHs. Implementation of the laboratory results utilizing a pilot scale equipment did not improve the performance, which may be due to the shorter contact time between the washing solution and the particles, or changes in physical characteristics of the leaching solution due to the elevated pressure utilized. The ecotoxicological evaluation, Microtox, demonstrated that all soil washing treatments increased the toxicity of soil leachates, possibly due to increased availability of contaminants and toxicity of soil washing solutions to the test organism.
authors.affiliation: Man-Technology-Environment Research Center, School of Science and Technology, Orebro University, SE-701 82 Orebro, Sweden. kristin.elgh-dalgren@oru.se
authors.forename: Kristin
authors.initials: K
authors.lastname: Elgh-Dalgren
authors.forename: Zandra
authors.initials: Z
authors.lastname: Arwidsson
authors.forename: Aida
authors.initials: A
authors.lastname: Camdzija
authors.forename: Ragnar
authors.initials: R
authors.lastname: Sjöberg
authors.forename: Veronica
authors.initials: V
authors.lastname: Ribé
authors.forename: Sylvia
authors.initials: S
authors.lastname: Waara
authors.forename: Bert
authors.initials: B
authors.lastname: Allard
authors.forename: Thomas
authors.initials: T
authors.lastname: von Kronhelm
authors.forename: Patrick A W
authors.initials: PA
authors.lastname: van Hees
mesh_terms: D002614:Chelating Agents; D003666:Decontamination; D008823:Micelles; D010865:Pilot Projects; D011084:Polycyclic Aromatic Hydrocarbons / Q000302:isolation & purification* / Q000633:toxicity; D012987:Soil; D012989:Soil Pollutants / Q000302:isolation & purification*; D012995:Solubility; D013501:Surface-Active Agents; D018675:Toxicity Tests; D014934:Wood / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D008823:Micelles; D011084:Polycyclic Aromatic Hydrocarbons; D012987:Soil; D012989:Soil Pollutants; D013501:Surface-Active Agents