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Remediation of materials with mixed contaminants: treatability, technology and final disposal
Örebro University, School of Science and Technology. (MTM Research Center)
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Contaminated soils are a large issue worldwide and much effort has been made to find efficient remediation methods. At many contaminated sites, mixtures of dif­ferent contaminants with different properties are present, which may lead to addi­tional problems, and thus additional costs, during the remediation process. This thesis presents the results from soil remedia­tion of two mixed contaminated soils, containing explosives and heavy metals and polycyclic aromatic hydrocarbons (PAH) and arsenic, respectively. The re­sults demonstrate that bioremediation may be an efficient method for moderate explosives concentration, but that too high contaminant concentrations may prevent the biodegradation, measured by both chemical and ecotoxicological analyses. If the contaminant concentration is very high, soil washing with alkaline pH (~12, NaOH) may be a good alterna­tive, which was observed to remove both explosives and heavy metals.

For a PAH and arsenic contaminated soil, little degradation of organics was ob­served during the bioremediation. However, the arsenic present was re-distributed in the soil, which could poten­tially lead to increased availability and thus in­creased risk for contaminant spreading. Soil washing at alkaline pH (~12-13; Ca(OH)2) with a combination of a biodegradable non-ionic sur­factant and a biodegradable chelating agent, executed at high temperature (50°C), reached treatment goals for both arsenic and PAH after 10 min treatment. Measurement of ecotoxicity using Microtox® demonstrated that remaining surfactant in the soil may lead to increased toxicity despite lower con­taminant concentrations.

Soil is a basically non-renewable resource and thus re-cycling of remediated soil ought to be commonly occurring. Yet, the re-cycling of remediated masses has so far been limited in Sweden, mainly because of the risk of spreading of pollu­tant remains. However, a recent proposition from the Swedish EPA opens for re-cycl­ing, even though the thresholds are very con­servative. Risk assessment of the re­mediated soil includes the utilization of leach­ing tests to estimate the risk of spreading of remaining pollutants. A comparison of the leaching from four reme­diated soils using three different leaching solutions reveals that leaching of both heavy metals and PAH occurs. In addition, differ­ences between different legisla­tions were observed, which could imply that the same soil could be re-cycled in one country (the Netherlands) but not another (Sweden).

Place, publisher, year, edition, pages
Örebro: Örebro universitet , 2009. , 54 p.
Series
Örebro Studies in Environmental Science, ISSN 1650-6278 ; 13
Keyword [en]
Bioremediation, Microtox®, mixed contaminants, re-cycling, soil remediation, soil washing.
National Category
Environmental Sciences
Research subject
Enviromental Science
Identifiers
URN: urn:nbn:se:oru:diva-7993ISBN: 978-91-7668-683-6 (print)OAI: oai:DiVA.org:oru-7993DiVA: diva2:236476
Public defence
2009-10-23, HSP2, Fakultetsgatan 1, Örebro, 10:15 (Swedish)
Opponent
Supervisors
Available from: 2009-09-29 Created: 2009-09-23 Last updated: 2011-04-29Bibliographically approved
List of papers
1. Anaerobic bioremediation of a soil with mixed contaminants: Explosives degradation and influence on heavy metal distribution, monitored as changes in concentration and toxicity
Open this publication in new window or tab >>Anaerobic bioremediation of a soil with mixed contaminants: Explosives degradation and influence on heavy metal distribution, monitored as changes in concentration and toxicity
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2009 (English)In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 202, no 1-4, 301-313 p.Article in journal (Refereed) Published
Abstract [en]

Two soils with explosives and metals were evaluated for the degradation efficiency of explosives by native microorganisms under anaerobic conditions. The commercially available method Daramend®, amended with zero-valent iron (ZVI), was compared with a horse-manure amended compost and a treatment with ZVI alone. In a moderately contaminated soil, Daramend® and ZVI treatment gave significantly higher removal rates compared  to compost and control treatments (Tukey’s test, P<0.05). The largest overall decrease in ecotoxicity, measured with bioluminescent bacteria (Vibrio fischeri), was achieved with ZVI-treatment. In a more contaminated soil no degradation of contaminants and no decline in soil toxicity could be distinguished after the same time period. Problems with establishment of anaerobic conditions during parts of the remediation process and low microbial activity due to acute toxicity of contaminants are plausible explanations. Redistribution that could potentially lead to mobilization of the co-contaminant Pb was not observed in either of the soils during the biological treatments.

Place, publisher, year, edition, pages
Springer Netherlands, 2009
Keyword
Bioremediation, explosives, Pb, Microtox®, mixed contaminants
National Category
Natural Sciences Environmental Sciences Inorganic Chemistry
Research subject
Environmental Chemistry
Identifiers
urn:nbn:se:oru:diva-5969 (URN)10.1007/s11270-009-9977-z (DOI)000269007400026 ()2-s2.0-69049092648 (Scopus ID)
Available from: 2009-03-09 Created: 2009-03-09 Last updated: 2017-02-20Bibliographically approved
2. Simultaneous re­mediation of explosives and lead from contaminated soil by pH-adjust­ment
Open this publication in new window or tab >>Simultaneous re­mediation of explosives and lead from contaminated soil by pH-adjust­ment
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Soil washing with pH-adjusted water was evaluated in two soils containing dif­ferent concentrations of heavy metals and explosives. Overall, the most efficient treatment was with water adjusted to pH 12 by NaOH. For explosives, pH 12 removed significantly higher amounts (P<0.05) of RDX and TNT compared to pH 4 (adjusted with HNO3) and distilled water in a moderately contaminated soil (230 mg HMX/kg, 1340 mg RDX/kg, 450 mg TNT/kg). In a more highly contaminated soil (6080 mg HMX/kg, 28740 mg RDX/kg, 3120 mg TNT/kg), the pH 12-treatment was the most efficient for removal of TNT and 2,4-DNT. Explosives removal increased with treatment time, probably due to the kineti­cally slow processes underlying the explosives degradation. Mobilization of heavy metals was strongly dependent on pH, with pH 12 mobilizing more than pH 3. In addition, the change in distribution coefficient (Kd) was more pro­nounced for local contaminants Pb and Cd in comparison with Cu and Zn, which were present in background concentrations.

National Category
Environmental Sciences
Research subject
Enviromental Science
Identifiers
urn:nbn:se:oru:diva-7990 (URN)
Available from: 2009-09-23 Created: 2009-09-23 Last updated: 2016-12-14Bibliographically approved
3. Bioremediation of a soil industrially contaminated by wood preservatives: degradation of polycyclic aromatic hydro­carbons and monitoring of coupled arsenic distribution
Open this publication in new window or tab >>Bioremediation of a soil industrially contaminated by wood preservatives: degradation of polycyclic aromatic hydro­carbons and monitoring of coupled arsenic distribution
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2011 (English)In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 214, no 1-4, 275-285 p.Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Springer Netherlands, 2011
Keyword
Arsenic, Bioremediation, Microtox®, PAH, Surfactant
National Category
Environmental Sciences
Research subject
Enviromental Science
Identifiers
urn:nbn:se:oru:diva-7991 (URN)10.1007/s11270-010-0422-0 (DOI)000285468800023 ()2-s2.0-78650592420 (Scopus ID)
Available from: 2009-09-23 Created: 2009-09-23 Last updated: 2017-02-15Bibliographically approved
4. 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
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2009 (English)In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 172, no 2-3, 1033-1040 p.Article 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
Keyword
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: 2017-02-17Bibliographically approved
5. Re-cycling of Remediated Soil in Sweden: An Environmental Advantage?
Open this publication in new window or tab >>Re-cycling of Remediated Soil in Sweden: An Environmental Advantage?
2008 (English)In: Resources, Conservation and Recycling, ISSN 0921-3449, Vol. 52, no 12, 1349-1361 p.Article in journal (Refereed) Published
Abstract [en]

The disposal of soil material after ex-situ treatment of contaminated soil is an issue of growing concern. The handling and use of this material are surrounded by numerous regulatory, economic, technical and societal aspects that complicate or hinder recycling. As a consequence, the lack of means of recovery can in the long term bias the whole remedial process. In addition, it can affect the competition between various treatment options such as ex-situ, and in-situ techniques and landfilling. At the same time the materials must not have any negative environmental impacts, and their usage must be compatible with existing risk assessment and management frameworks regarding contaminated land. Other concerns such as a possible distinction against “lightly” contaminated materials, waste status and public acceptance add to the complexity. This paper focuses on Swedish conditions, but does also provide an outlook concerning EU regulation. A summary of leaching and batch tests employed for re-use of soil and waste is presented as well as an overview of the eco-toxicological aspects of treated materials. The main conclusion is that re-cycling of treated soil is desirable from numerous aspects, but has to go along an adequate risk assessment.

Place, publisher, year, edition, pages
Amsterdam: Elsevier, 2008
Keyword
Environmental impact; Re-cycling; Remediation; Soil; Waste
National Category
Natural Sciences Environmental Sciences
Research subject
Environmental Chemistry
Identifiers
urn:nbn:se:oru:diva-7989 (URN)10.1016/j.resconrec.2008.07.016 (DOI)
Available from: 2009-09-23 Created: 2009-09-23 Last updated: 2016-12-02Bibliographically approved
6. Re-cycling of remediated soil: evaluation of leaching tests as tools for characterization
Open this publication in new window or tab >>Re-cycling of remediated soil: evaluation of leaching tests as tools for characterization
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2011 (English)In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 31, no 2, 215-224 p.Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Pergamon Press, 2011
Keyword
Heavy metals, Leaching test, PAH, Re-cycling
National Category
Environmental Sciences
Research subject
Enviromental Science
Identifiers
urn:nbn:se:oru:diva-7992 (URN)10.1016/j.wasman.2009.12.021 (DOI)000286411400003 ()20117924 (PubMedID)2-s2.0-78649838340 (Scopus ID)
Available from: 2009-09-23 Created: 2009-09-23 Last updated: 2017-02-14Bibliographically approved

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