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  • 1.
    Arwidsson, Zandra
    Örebro University, School of Science and Technology.
    Organic complexing agents for remediation of heavy metal contaminated soil2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Soil washing of heavy metal contaminated soil may be enhanced by the addition of synthetic chelators. Since many of these chelators may imply stress to soil organisms and are poorly biodegraded, identification and evaluation of effective biodegradable or recyclable chelators (synthetic and/or naturally produced) is of great interest. The efficiency of biodegradable synthetic chelators was evaluated both in bench- (0.3 kg) and meso- (10 kg) scale. Results demonstrated that the solubilization of copper, lead, and zinc was similar in bench- and meso-scale systems, which indicated that these systems could be used in a technical scale. However, the arsenic extraction in meso-scale system, were non-conclusive. Due to the high cost involved in the purchase of synthetic chelating agents, recycling of the solutions is of great interest, and this was achieved in five consecutive washing cycles. Considering the economy of a full-scale process, recycling of complexing solutions with sulfide addition at each cycle, both at the 100 mM-level, appears feasible. Naturally derived chelators were produced by saprotrophic fungi and through alkaline degradation of humic substances and cellulose. The results demonstrated that these types of complexing agents are not as effective as the synthetic chelators. In the fungal systems, desorption of metals was related to production of organic complexing acids, but mainly to the pH-decrease. Nonetheless, in some systems, formation of soluble complexes was indicated (copper). Enhancement of copper, lead, and zinc release with the use of alkaline leachates from wood and peat appeared possible. Since these agents have a natural origin and are derived from rather cheap raw material, recycling is not an issue.

     

    List of papers
    1. Remediation of Metal Contaminated Soil by Organic Metabolites from Fungi I—Production of Organic Acids
    Open this publication in new window or tab >>Remediation of Metal Contaminated Soil by Organic Metabolites from Fungi I—Production of Organic Acids
    Show others...
    2008 (English)In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 205, no 1-4, p. 215-226Article in journal (Refereed) Published
    Abstract [en]

    Investigations were made on living strains offungi in a bioremediation process of three metal (lead)contaminated soils. Three saprotrophic fungi (Aspergillusniger, Penicillium bilaiae, and a Penicillium sp.) wereexposed to poor and rich nutrient conditions (no carbonavailability or 0.11 M D-glucose, respectively) andmetal stress (25 μM lead or contaminated soils) for5 days. Exudation of low molecular weight organicacids was investigated as a response to the metal andnutrient conditions. Main organic acids identified wereoxalic acid (A. niger) and citric acid (P. bilaiae).Exudation rates of oxalate decreased in response tolead exposure, while exudation rates of citrate were lessaffected. Total production under poor nutrient conditionswas low, except for A. niger, for which nosignificant difference was found between the poor andrich control. Maximum exudation rates were 20 μmoloxalic acid g^−1 biomass h^−1 (A. niger) and 20 μmolcitric acid g^−1 biomass h^−1 (P. bilaiae), in the presenceof the contaminated soil, but only 5 μmol organic acidsg^−1 biomass h^−1, in total, for the Penicillium sp. Therewas a significant mobilization of metals from the soilsin the carbon rich treatments and maximum release ofPb was 12% from the soils after 5 days. This was notsufficient to bring down the remaining concentration tothe target level 300 mg kg^−1 from initial levels of 3,800,1,600, and 370 mg kg^−1in the three soils. Target levelsfor Ni, Zn, and Cu, were 120, 500, and 200 mg kg^−1,respectively, and were prior to the bioremediationalready below these concentrations (except for Cu Soil1). However, maximum release of Ni, Zn, and Cu was28%, 35%, and 90%, respectively. The release of metalswas related to the production of chelating acids, but alsoto the pH-decrease. This illustrates the potential to usefungi exudates in bioremediation of contaminated soil.Nonetheless, the extent of the generation of organicacids is depending on several processes and mechanismsthat need to be further investigated.

    Place, publisher, year, edition, pages
    Berlin, Germany: Springer, 2008
    Keywords
    Bioremediation, Citric acid, Fungi, Lead, Organic acids, Oxalic acid
    National Category
    Natural Sciences Environmental Sciences
    Research subject
    Environmental Chemistry
    Identifiers
    urn:nbn:se:oru:diva-11843 (URN)10.1007/s11270-009-0067-z (DOI)000272851000016 ()2-s2.0-75049083063 (Scopus ID)
    Available from: 2010-09-15 Created: 2010-09-15 Last updated: 2017-12-12Bibliographically approved
    2. Remediation of Metal-Contaminated Soil by Organic Metabolites from Fungi II-Metal Redistribution
    Open this publication in new window or tab >>Remediation of Metal-Contaminated Soil by Organic Metabolites from Fungi II-Metal Redistribution
    2010 (English)In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 207, no 1-4, p. 5-18Article in journal (Refereed) Published
    Abstract [en]

    Exudation of low molecular weight organic acids by fungi was studied in a project focusing on bioremediation of metal-contaminated soils. The production of acids (mainly oxalic and citric acid) as a response to nutrient variations and presence of metals has recently been reported (Arwidsson et al. 2009). A significant release of metals was observed and was related not only to the production of organic acids but also to the resulting pH decrease in the systems. The processes governing the release and redistribution of metals in the soil-water fungus system were the focus of the present continuation of the project, based on observations of Aspergillus niger, Penicillium bilaiae, and a Penicillium sp. The release of lead was 12% from the soil with the second highest initial load (1,600 mg kg(-1)), while the release of copper was 90% from the same soil (140 mg kg(-1)). The dominating mechanism behind the release and subsequent redistribution was the change in pH, going from near neutral to values in the range 2.1-5.9, reflecting the production of organic acids. For some of the systems, the formation of soluble complexes is indicated (copper, at intermediate pH) which favors the metal release. Iron is assumed to play a key role since the amount of secondary iron in the soils is higher than the total load of secondary heavy metals. It can be assumed that most of the heavy metals are initially associated with iron-rich phases through adsorption or coprecipitation. These phases can be dissolved, or associated metals can be desorbed, by a decrease in pH. It would be feasible to further develop a process in technical scale for remediation of metal-contaminated soil, based on microbial metabolite production leading to formation of soluble metal complexes, notably with copper.

    Keywords
    Bioremediation, Fungi, Metals, Oxalic acid, Citric acid
    National Category
    Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-13015 (URN)10.1007/s11270-009-0222-6 (DOI)000274550700002 ()
    Available from: 2011-01-03 Created: 2011-01-03 Last updated: 2018-04-19Bibliographically approved
    3. Leaching of metals from contamined soil with polyhydroxycarboxylic acids of natural origin
    Open this publication in new window or tab >>Leaching of metals from contamined soil with polyhydroxycarboxylic acids of natural origin
    (English)Manuscript (preprint) (Other academic)
    National Category
    Environmental Sciences
    Research subject
    Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-15427 (URN)
    Available from: 2011-04-29 Created: 2011-04-29 Last updated: 2017-10-17Bibliographically approved
    4. Remediation of heavy metal contaminated soil washing residues with amino polycarboxylic acids
    Open this publication in new window or tab >>Remediation of heavy metal contaminated soil washing residues with amino polycarboxylic acids
    Show others...
    2010 (English)In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 173, no 1-3, p. 697-704Article in journal (Refereed) Published
    Abstract [en]

    Removal of Cu, Pb, and Zn by the action of the two biodegradable chelating agents [S,S]-ethylenediaminedisuccinic acid (EDDS) and methylglycinediacetic acid (MGDA), as well as citric acid, was tested. Three soil samples, which had previously been treated by conventional soil washing (water), were utilized in the leaching tests. Experiments were performed in batches (0.3 kg-scale) and with a WTC-mixer system (Water Treatment Construction, 10 kg-scale). EDDS and MGDA were most often equally efficient in removing Cu, Pb, and Zn after 10-60 min. Nonetheless, after 10 d, there were occasionally significant differences in extraction efficiencies. Extraction with citric acid was generally less efficient, however equal for Zn (mainly) after 10 d. Metal removal was similar in batch and WTC-mixer systems, which indicates that a dynamic mixer system could be used in full-scale. Use of biodegradable amino polycarboxylic acids for metal removal, as a second step after soil washing, would release most remaining metals (Cu, Pb and Zn) from the present soils, however only after long leaching time. Thus, a full-scale procedure, based on enhanced metal leaching by amino polycarboxylic acids from soil of the present kind, Would require a pre-leaching step lasting several days in order to be efficient. (C) 2009 Elsevier B.V. All rights reserved.

    Keywords
    Heavy metals, Amino polycarboxylic acids, Soil, Remediation, EDDS, MGDA
    National Category
    Chemical Sciences
    Research subject
    Chemistry
    Identifiers
    urn:nbn:se:oru:diva-13043 (URN)10.1016/j.jhazmat.2009.08.141 (DOI)000273135600098 ()
    Available from: 2011-01-03 Created: 2011-01-03 Last updated: 2018-04-19Bibliographically approved
    5. Recycling of amino polycarboxylic acids in soil washing of heavy metal contaminated soil
    Open this publication in new window or tab >>Recycling of amino polycarboxylic acids in soil washing of heavy metal contaminated soil
    (English)Manuscript (preprint) (Other academic)
    National Category
    Environmental Sciences
    Research subject
    Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-15428 (URN)
    Available from: 2011-04-29 Created: 2011-04-29 Last updated: 2017-10-17Bibliographically approved
    6. Laboratory and pilot scale soil washing of PAH and arsenic from a wood preservation site: Changes in concentration and toxicity
    Open this publication in new window or tab >>Laboratory and pilot scale soil washing of PAH and arsenic from a wood preservation site: Changes in concentration and toxicity
    Show others...
    2009 (English)In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 172, no 2-3, p. 1033-1040Article in journal (Refereed) Published
    Abstract [en]

    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 3.2xCMC* of a nonionic, alkyl glucoside surfactant at pH 12 (Ca(OH)2). This combination managed to reach Swedish threshold values within 10 min of treat­ment when performed at elevated temperature (50°C), with initial conta­minant concentrations of As = 105±4 mg/kg and US-EPA PAH16 = 46.0±2.3 mg/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.

    Place, publisher, year, edition, pages
    Amsterdam: Elsevier, 2009
    Keywords
    Arsenic, Microtox®, PAH, Soil washing, Surfactant
    National Category
    Environmental Sciences
    Research subject
    Enviromental Science
    Identifiers
    urn:nbn:se:oru:diva-7988 (URN)10.1016/j.jhazmat.2009.07.092 (DOI)000271980800068 ()19699582 (PubMedID)2-s2.0-71049155866 (Scopus ID)
    Available from: 2009-09-23 Created: 2009-09-23 Last updated: 2017-12-13Bibliographically approved
  • 2.
    Arwidsson, Zandra
    et al.
    Örebro University, School of Science and Technology. SAKAB AB, Kumla, Sweden.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Remediation of Metal-Contaminated Soil by Organic Metabolites from Fungi II-Metal Redistribution2010In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 207, no 1-4, p. 5-18Article in journal (Refereed)
    Abstract [en]

    Exudation of low molecular weight organic acids by fungi was studied in a project focusing on bioremediation of metal-contaminated soils. The production of acids (mainly oxalic and citric acid) as a response to nutrient variations and presence of metals has recently been reported (Arwidsson et al. 2009). A significant release of metals was observed and was related not only to the production of organic acids but also to the resulting pH decrease in the systems. The processes governing the release and redistribution of metals in the soil-water fungus system were the focus of the present continuation of the project, based on observations of Aspergillus niger, Penicillium bilaiae, and a Penicillium sp. The release of lead was 12% from the soil with the second highest initial load (1,600 mg kg(-1)), while the release of copper was 90% from the same soil (140 mg kg(-1)). The dominating mechanism behind the release and subsequent redistribution was the change in pH, going from near neutral to values in the range 2.1-5.9, reflecting the production of organic acids. For some of the systems, the formation of soluble complexes is indicated (copper, at intermediate pH) which favors the metal release. Iron is assumed to play a key role since the amount of secondary iron in the soils is higher than the total load of secondary heavy metals. It can be assumed that most of the heavy metals are initially associated with iron-rich phases through adsorption or coprecipitation. These phases can be dissolved, or associated metals can be desorbed, by a decrease in pH. It would be feasible to further develop a process in technical scale for remediation of metal-contaminated soil, based on microbial metabolite production leading to formation of soluble metal complexes, notably with copper.

  • 3.
    Arwidsson, Zandra
    et al.
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Elgh-Dalgren, Kristin
    Örebro University, School of Science and Technology.
    van Hees, Patrick
    Örebro University, School of Science and Technology.
    Recycling of amino polycarboxylic acids in soil washing of heavy metal contaminated soilManuscript (preprint) (Other academic)
  • 4.
    Arwidsson, Zandra
    et al.
    Örebro University, School of Science and Technology. SAKAB AB, Kumla, Sweden.
    Elgh-Dalgren, Kristin
    Örebro University, School of Science and Technology.
    von Kronhelm, Thomas
    SAKAB AB, Kumla, Sweden.
    Sjoberg, Ragnar
    Solvent AB, Motala, Sweden.
    Allard, Bert
    Örebro University, School of Science and Technology.
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Remediation of heavy metal contaminated soil washing residues with amino polycarboxylic acids2010In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 173, no 1-3, p. 697-704Article in journal (Refereed)
    Abstract [en]

    Removal of Cu, Pb, and Zn by the action of the two biodegradable chelating agents [S,S]-ethylenediaminedisuccinic acid (EDDS) and methylglycinediacetic acid (MGDA), as well as citric acid, was tested. Three soil samples, which had previously been treated by conventional soil washing (water), were utilized in the leaching tests. Experiments were performed in batches (0.3 kg-scale) and with a WTC-mixer system (Water Treatment Construction, 10 kg-scale). EDDS and MGDA were most often equally efficient in removing Cu, Pb, and Zn after 10-60 min. Nonetheless, after 10 d, there were occasionally significant differences in extraction efficiencies. Extraction with citric acid was generally less efficient, however equal for Zn (mainly) after 10 d. Metal removal was similar in batch and WTC-mixer systems, which indicates that a dynamic mixer system could be used in full-scale. Use of biodegradable amino polycarboxylic acids for metal removal, as a second step after soil washing, would release most remaining metals (Cu, Pb and Zn) from the present soils, however only after long leaching time. Thus, a full-scale procedure, based on enhanced metal leaching by amino polycarboxylic acids from soil of the present kind, Would require a pre-leaching step lasting several days in order to be efficient. (C) 2009 Elsevier B.V. All rights reserved.

  • 5.
    Arwidsson, Zandra
    et al.
    Örebro University, School of Science & Technology, Örebro, Sweden; SAKAB AB, Kumla, Sweden.
    Johansson, Emma M.
    Örebro University, School of Science and Technology.
    von Kronhelm, Thomas
    SAKAB AB, Kumla Sweden.
    Allard, Bert
    Örebro University, School of Science and Technology.
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology. Eurofins Environment Sweden AB, Lidköping, Sweden.
    Remediation of Metal Contaminated Soil by Organic Metabolites from Fungi I—Production of Organic Acids2008In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 205, no 1-4, p. 215-226Article in journal (Refereed)
    Abstract [en]

    Investigations were made on living strains offungi in a bioremediation process of three metal (lead)contaminated soils. Three saprotrophic fungi (Aspergillusniger, Penicillium bilaiae, and a Penicillium sp.) wereexposed to poor and rich nutrient conditions (no carbonavailability or 0.11 M D-glucose, respectively) andmetal stress (25 μM lead or contaminated soils) for5 days. Exudation of low molecular weight organicacids was investigated as a response to the metal andnutrient conditions. Main organic acids identified wereoxalic acid (A. niger) and citric acid (P. bilaiae).Exudation rates of oxalate decreased in response tolead exposure, while exudation rates of citrate were lessaffected. Total production under poor nutrient conditionswas low, except for A. niger, for which nosignificant difference was found between the poor andrich control. Maximum exudation rates were 20 μmoloxalic acid g^−1 biomass h^−1 (A. niger) and 20 μmolcitric acid g^−1 biomass h^−1 (P. bilaiae), in the presenceof the contaminated soil, but only 5 μmol organic acidsg^−1 biomass h^−1, in total, for the Penicillium sp. Therewas a significant mobilization of metals from the soilsin the carbon rich treatments and maximum release ofPb was 12% from the soils after 5 days. This was notsufficient to bring down the remaining concentration tothe target level 300 mg kg^−1 from initial levels of 3,800,1,600, and 370 mg kg^−1in the three soils. Target levelsfor Ni, Zn, and Cu, were 120, 500, and 200 mg kg^−1,respectively, and were prior to the bioremediationalready below these concentrations (except for Cu Soil1). However, maximum release of Ni, Zn, and Cu was28%, 35%, and 90%, respectively. The release of metalswas related to the production of chelating acids, but alsoto the pH-decrease. This illustrates the potential to usefungi exudates in bioremediation of contaminated soil.Nonetheless, the extent of the generation of organicacids is depending on several processes and mechanismsthat need to be further investigated.

  • 6.
    Arwidsson, Zandra
    et al.
    Örebro University, School of Science and Technology.
    Ålund, Marie
    Örebro University, School of Science and Technology.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Leaching of metals from contamined soil with polyhydroxycarboxylic acids of natural originManuscript (preprint) (Other academic)
  • 7.
    Arwidsson, Zandra
    et al.
    SAKAB AB, Norrtorp, Sweden.
    Ålund, Marie
    SAKAB AB, Norrtorp, Sweden.
    Allard, Bert
    Örebro University, School of Science and Technology.
    Karlsson, Stefan
    Örebro University, School of Science and Technology.
    Metal mobilisation from soils and sediments by hydroxycarboxylic acids of natural origin2011In: Programme and Abstracts: 25th International Applied Geochemistry Symposium, 22-26 August, 2011, Rovaniemi, Finland / [ed] Pertti Sarala, V. Juhani Ojala, Marja-Leena Porsanger, Vuorimiesyhdistys - Finnish Association of Mining and Metallurgical Engineers , 2011, p. 77-77Conference paper (Refereed)
  • 8.
    Elgh-Dalgren, Kristin
    et al.
    Örebro University, School of Science and Technology.
    Arwidsson, Zandra
    Sakab AB.
    Camdzija, Aida
    Sjöberg, Ragnar
    Ribé, Veronica
    Mälardalen University.
    Waara, Sylvia
    Mälardalen University.
    Allard, Bert
    Örebro University, School of Science and Technology.
    von Kronhelm, Thomas
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Laboratory and pilot scale soil washing of PAH and arsenic from a wood preservation site: Changes in concentration and toxicity2009In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 172, no 2-3, p. 1033-1040Article in journal (Refereed)
    Abstract [en]

    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 3.2xCMC* of a nonionic, alkyl glucoside surfactant at pH 12 (Ca(OH)2). This combination managed to reach Swedish threshold values within 10 min of treat­ment when performed at elevated temperature (50°C), with initial conta­minant concentrations of As = 105±4 mg/kg and US-EPA PAH16 = 46.0±2.3 mg/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.

  • 9.
    Elgh-Dalgren, Kristin
    et al.
    Örebro University, School of Science and Technology.
    Arwidsson, Zandra
    Ribé, Veronica
    Mälardalen University, Västerås, Sweden.
    Waara, Sylvia
    Mälardalen University, Västerås, Sweden.
    von Kronhelm, Thomas
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Bioremediation of a soil industrially contaminated by wood preservatives: degradation of polycyclic aromatic hydro­carbons and monitoring of coupled arsenic distribution2011In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 214, no 1-4, p. 275-285Article in journal (Refereed)
    Abstract [en]

    Two commercially available aerobic bioremediation methods (Daramend® and BioSan) were utilized to study the aerobic biodegradation of polycyclic aro­matic hydrocarbons (PAH) and the effect of the simultaneously present arsenic. The soil was collected at an old wood preservation site and the initial PAH16-concentration was 46 mg/kg, with mainly high molecular weight congeners. The As-concentration was105 mg/kg with low availability as assessed with se­quential extraction. To enahce the availability of PAH, the effect of a non-ionic surfactant was evaluated. Degradation of both low and high molecular weight PAH was observed, however after 30 weeks, the degradation was generally low and no treatment was significantly better than the others. The treatments had, on the other hand, an effect on As-distribution, with increased As-concentra­tion in the available fraction after treatment. This may be due to both the mi­crobial activity and the presence of anoxic micro sites in the soil. The overall efficiency of the biological treatment was further evaluated using the standar­dized ecotoxicity test utilizing Vibrio fischeri (Microtox®). The toxicity test demonstrated that the bioremediation led to an increase in toxicity, especially in treatments receiving surfactant. The surfactant implied an increase in conta­minant availability but also a decrease in surface tension, which might have contributed to the overall toxicity increase.

  • 10.
    Elgh-Dalgren, Kristin
    et al.
    Örebro University, School of Science and Technology.
    Arwidsson, Zandra
    Örebro University, School of Science and Technology.
    Sjöberg, Ragnar
    Allard, Bert
    Örebro University, School of Science and Technology.
    von Kronhelm, Tomas
    van Hees, Patrick
    Örebro University, School of Science and Technology.
    Effect of chemical amendments on the distribution of arsenic and polycyclic aromatic hydrocarbons in a contaminated soil2009Conference paper (Refereed)
  • 11.
    Elgh-Dalgren, Kristin
    et al.
    Örebro University, School of Science and Technology.
    Düker, Anders
    Örebro University, School of Science and Technology.
    Arwidsson, Zandra
    Örebro University, School of Science and Technology.
    von Kronhelm, Thomas
    van Hees, Patrick A. W.
    Örebro University, School of Science and Technology.
    Re-cycling of remediated soil: evaluation of leaching tests as tools for characterization2011In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 31, no 2, p. 215-224Article in journal (Refereed)
    Abstract [en]

    In Sweden, leaching tests with deionized water (D.W.) are frequently utilized in risk assessment, but implementation of these results to evaluate the risk of spreading in the environment is difficult. One problem is that most leaching procedures only consider heavy metals release, whereas organic pollutants are left out. The aim of the present study was to assess the possible pollutant miti­gation in four remediated soils, three with heavy metals and one with polycyclic aromatic hydrocarbons (PAH), utilizing three different leaching solutions: D.W., a weak ionic solution (0.001 M CaCl2) and an artificially made soil wa­ter (ASW). In general, batch leaching implied larger contaminant removal than column leaching, possibly due to the more rough treatment of the soil particles, and guidelines would at times be exceeded by batch leaching but not column leaching. Utilization of CaCl2 was found to release much less heavy metal than D.W., whereas the metals mobilized by ASW were removed from solution by the filtration of soil leachates. Low molecular weight PAH was most efficiently mobilized by CaCl2, while D.W. worked better for high molecular weight PAH. Despite very low initial PAH-concentrations, tap- and groundwater criteria were exceeded by all leaching solutions.

  • 12.
    Ålund, Marie
    et al.
    Man-Technology-Environment Research Centre, Örebro University, Örebro, Sweden.
    Arwidsson, Zandra
    Örebro University, School of Science and Technology. SAKAB AB, Kumla, Sweden .
    Allard, Bert
    Örebro University, School of Science and Technology.
    Leaching of metals from contaminated soil with polyhydroxicarboxylic acids of natural origin2009Conference paper (Refereed)
    Abstract [en]

    The effect of addition of complexing agents, generated from natural products, on the release and redistribution of metals from contaminated soil has been studied. Water soluble humic substances (fulvic acids, FA) generated by leaching of high-molecular weight humic matter (peat) at high pH, and isosaccharinic acid (ISA), generated by degradation of wood (saw-dust) at high pH was used and compared with some synthetic complexing agents representing naturally occurring products: Citric acid (CA), ethylenediamine disuccinic acid (EDDS) and methylglycine diacetic acid (MGDA).

    Four contaminated soils with elevated levels of particularly As, Cr, Cu, Ni and Pb at maximum levels of 1.5, 1.2, 1.7, 0.14 and 3.8 g/kg, respectively (two from shooting-ranges, one from a steel-works site and one from a wood impregnation site) were leached with alkaline solutions (pH 12) containing peat degradation products (1.2 g/l TOC; some 90 % FAs) and wood degradation products (0.7 g/l TOC, some 50-60 % ISA), as well as solutions of CA, EDDS and MGDA (0.25 mM, pH 6-8). Metal releases were analysed after various leaching times: 24 h, 1 week, 5 weeks. Results are related to the total content of metals in the soil (XRF-analysis), total leachable fractions (sequential leaching according to Tessier) and leaching with nitric acid (pH 3).

    A release of some 10 % of the lead inventory and up to 50 % of the copper in one of the soils could be achieved in the FA and ISA leaching systems, while the synthesised agents EDDS and MGDA led to releases of some 60-90 %. The effects of FA and ISA were generally significantly lower than those of the other complexing agents for As, Cr, and Ni, but significantly higher for V (present at the level 40 mg/kg). Thus, a significant enhancement of the release of particularly copper and lead from the contaminated soils by leaching with alkaline (pH 12) leachates of wood and/or peat appears to be feasible.

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