| 1. |
- Amofah, Lea Rastas, et al.
(författare)
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Extraction of arsenic from soils contaminated with wood preservation chemicals
- 2010
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Ingår i: Soil & sediment contamination. - : Informa UK Limited. - 1532-0383 .- 1549-7887. ; 19:2, s. 142-159
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Tidskriftsartikel (refereegranskat)abstract
- Three soil samples contaminated by chromated zinc arsenate (CZA) or chromated copper arsenate (CCA) were investigated in a laboratory scale to study As mobilization and to identify a chemical agent that could be used in soil washing to extract arsenic. Besides high As extraction, the cost, occupational health issues and technical aspects were considered when selecting the chemical. Arsenic is strongly bound to CZA/CCA soils; only ∼50% of the tot-As was removed from water-washed soils. High Fe or Al mobilization is not necessarily indicative of high As removal from CZA/CCA soils. A high Cu/As-ratio and a large amount of soluble Ca in the soil hampered As extraction. The high ratio can be an indication of stable Cu-arsenates in soil. Calcium can react with the extraction agent or with As during extraction. Sodium hydroxide, dithionite with citrate (and oxalate) (dithionite solutions), and oxalate with citrate were the most efficient chemicals for removing As from the soils. The disadvantages of using these strong chemicals are: a high cost (oxalate with citrate); damage to equipment (dithionite solutions); an adverse impact on occupational health (dithionite solutions); or a deterioration in soil quality after extraction (NaOH and dithionite solutons). Phosphate, solutions based on NH2OH·HCl, or citrate were not efficient in mobilizing As from the soils.
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| 2. |
- Amofah, Lea Rastas, et al.
(författare)
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The influence of temperature, pH/molarity and extractant on the removal of arsenic, chromium and zinc from contaminated soil
- 2011
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Ingår i: Journal of Soils and Sediments. - : Springer Science and Business Media LLC. - 1439-0108 .- 1614-7480. ; 11:8, s. 1334-1344
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Normal soil washing leave high residual pollutant content in soil. The remediation could be improved by targeting the extraction to coarser fractions. Further, a low/high extraction pH and higher temperature enhance the pollutant removal, but these measures are costly. In this study, the utility of NaOH, oxalate-citrate (OC) and dithionite-citrate-oxalate (DCO) solutions for extracting of arsenic, chromium and zinc from contaminated soil were assessed and compared. In addition the effects of NaOH concentration and temperature on NaOH extractions, and those of temperature and pH on OC and DCO extractions, were evaluated. Materials and methods: A two-level, full-factorial design with a centre point was implemented. Two factors, concentration and temperature,were evaluated in NaOH extractions, and pH and temperature for OC and DCO solutions. In all cases, the extraction temperature was 20°C, 30°C and 40°C. The studied NaOH concentrations were 0.05, 0.075 and 0.1 M. The pH in OC solutions was 3, 5 and 7, and in DCO solutions, 4.7, 6.3 and 6.7. Water-washed and medium coarse soil fraction of arsenic, chromium and zinc contaminated soil was agitated for 15 min with the extraction solution. Results and discussion: In NaOH extractions, the temperature and (less strongly) NaOH concentration significantly affected As and Cr mobilisation, but only the latter affected Zn mobilisation. Both pH and temperature significantly (and similarly) influenced As and Cr mobilisation in OC extractions, while only the pH influenced Zn mobilisation. In contrast, the extraction temperature (but not pH) influenced As, Cr and Zn mobilisation in DCO extractions. Conclusions: For all extractants, mobilisation was most efficient at elevated temperature (40°C). None of the extractants reduced the soil's As content to below the Swedish EPA's guideline value. Use of DCO is not recommended because dithionite has a short lifetime and residual arsenic contents in DCO-extracted soil are relatively high. Instead, sequential extraction with NaOH followed by OC solutions (affording significant reductions in As, Cr and Zn levels in the soil with short extraction times) at 40°C is recommended.
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| 3. |
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| 4. |
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| 5. |
- Herrmann, Inga, et al.
(författare)
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Hydraulic conductivity of fly ash : sewage sludge mixes for use in landfill cover liners
- 2009
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 43:14, s. 3541-3547
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Tidskriftsartikel (refereegranskat)abstract
- Secondary materials could help meeting the increasing demand of landfill cover liner materials. In this study, the effect of compaction energy, water content, ash ratio, freezing, drying and biological activity on the hydraulic conductivity of two fly ash - sewage sludge mixes was investigated using a 27-1 fractional factorial design. The aim was to identify the factors that influence hydraulic conductivity, to quantify their effects and to assess how a sufficiently low hydraulic conductivity can be achieved. The factors compaction energy and drying, as well as the factor interactions material×ash ratio and ash ratio×compaction energy affected hydraulic conductivity significantly (α = 0.05). Freezing on 5 freeze-thaw cycles did not affect hydraulic conductivity. Water content affected hydraulic conductivity only initially. The hydraulic conductivity data were modelled using multiple linear regression. The derived models were reliable as indicated by R2adjusted values between 0.75 and 0.86. Independent on the ash ratio and the material, hydraulic conductivity was predicted to be between 1.7 × 10-11 m s-1 and 8.9 × 10-10 m s-1 if the compaction energy was 2.4 J cm-3, the ash ratio between 20 and 75 % and drying did not occur. Thus, the investigated materials met the limit value for non-hazardous waste landfills of 10-9 m s-1.
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| 6. |
- Jia, Yu, et al.
(författare)
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Using shrimp shells and concrete to mitigate leaching for metals from waste rock
- 2023
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 30, s. 40825-40845
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Tidskriftsartikel (refereegranskat)abstract
- The capability of shrimp shells or construction demolition concrete as amendments to immobilize elements, primarily Pb and Zn, generated from mine waste weathering, was investigated via standard batch leaching test (L/S 10 cm3/g, 24 h). The effect of the amendment was tested at waste rock-to-residue ratios 9:1, 9.5:0.5, and 9.8:0.2 (weight:weight, w/w), with seawater as leachant. The effect of freshwater vs. seawater on the leaching pattern was investigated. The elemental contents of rock varied largely. Elemental levels in shells and concrete had much lower values than waste rock. Leaching results showed that amendment in both cases had high capacity to immobilize Pb and Zn. A decrease of concrete-to-rock ratio from 1:9 to 0.2:9.8 (w/w) led to more leaching of Pb but less of Zn. Similarly, decreasing shrimp-to-rock ratio increased and decreased leaching of Pb and Zn, respectively. Increasing experimental time to 5 and 10 d in a shrimp-amended batch caused less leaching of Pb and more of Zn. Both Pb and Zn immobilization in the concrete amendment was considered due to the increase of pH by concrete amending. The Pb leaching in the present study was considered controlled primarily by a sorption process, whilst the leaching for Zn might have been influenced by other factors such as pH and DO. Pb leaching from rock was much higher in seawater than in freshwater, with same range for Zn leaching, irrespective of leachant. It showed consistence between the laboratory data and the field conditions. Calculation procedures were established for amendment to mitigate mine drainage.
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| 7. |
- Kumpiene, Jurate, et al.
(författare)
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Assessment of zerovalent iron for stabilization of chromium, copper, and arsenic in soil
- 2006
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 144:1, s. 62-69
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Tidskriftsartikel (refereegranskat)abstract
- Stabilization of soil contaminated with trace elements is a remediation practice that does not reduce the total content of contaminants, but lowers the amounts of mobile and bioavailable fractions. This study evaluated the efficiency of Fe(0) to reduce the mobility and bioavailability of Cr, Cu, As and Zn in a chromated copper arsenate (CCA)-contaminated soil using chemical, biochemical and biotoxicity tests. Contaminated soil was stabilized with 1% iron grit. This treatment decreased As and Cr concentrations in leachates (by 98% and 45%, respectively), in soil pore water (by 99% and 94%, respectively) and in plant shoots (by 84% and 95%, respectively). The stabilization technique also restored most of analyzed soil enzyme activities and reduced microbial toxicity, as evaluated by the BioTox test. After stabilization, exchangeable and bioaccessible fractions of Cu remained high, causing some residual toxicity in the treated soil.
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| 8. |
- Kumpiene, Jurate, et al.
(författare)
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Editorial
- 2007
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Ingår i: Ambio. - 0044-7447 .- 1654-7209. ; 36:6, s. 429-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- During the last decades, contaminated soil has become of both public and scientific concern. National inventories have shown very large numbers of potentially contaminated sites originating from various industrial activities. Industrial technologies in the old days were often based on open systems designed without the insight of their being potential environmental threats. Legal actions taken against organizations responsible for water and air pollution have led to the development of new water and flue gas cleaning technologies. Today, contaminated land plays a major role in sustainable future land use, not only with regard to pollution resulting from old industrial activities but also with regard to the management of present industrial technologies and waste products.Issues related to contaminated soil are by definition interdisciplinary. In the Northern Sweden Soil Remediation Center (MCN), scientists from three universities (Umeå University, Luleå University of Technology, and Swedish University of Agricultural Sciences) and the Swedish Defense Research Agency (FOI) have focused on developing a detailed understanding of the mechanisms and processes in the soil system. Fundamental and applied research in collaboration with enterprises has been performed concerning critical knowledge gaps.The MCN was initiated in 2001 and consists of scientists, representatives from authorities, consultants, and entrepreneurs. The major goals of the MCN have been to increase the scientific basis for the risk assessment of contaminated soil and, by improved knowledge of the interactions between different contaminants and the soil system, to guide the development of remediation methods. New scientific results have been implemented by collaboration enterprises and authorities that have added strategic value for the whole sector in general.This issue of AMBIO summarizes the MCN's research activities, which have focused on inorganic and organic pollutant behavior, analytical methods, and risk assessments of brownfields. In addition, invited contributions from research groups outside the MCN have added other valuable aspects to the multidisciplinary research field.
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| 9. |
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| 10. |
- Kumpiene, Jurate, et al.
(författare)
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Evaluation of the critical factors controlling stability of chromium, copper, arsenic and zinc in iron-treated soil
- 2007
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Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 67:2, s. 410-417
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Tidskriftsartikel (refereegranskat)abstract
- Various environmental factors are expected to affect the mobility of elements in chemically stabilized soils. The aim of this study was to evaluate the effects of pH, oxidizing–reducing potential (Eh), liquid-to-solid ratio (L/S), presence of organic matter (OM) and microbial activity (MA) on the mobility of chromium, copper, arsenic and zinc in zerovalent iron (Fe0)-stabilized soil. A 25 full factorial design was applied to assess the leaching of the elements from the treated soil. The factor having the most impact on the mobility of Cr, Cu and Zn was pH; low pH (3) led to the release of these elements. Arsenic remobilization was controlled by L/S and MA, whilst Eh, though also significant, had less influence. In the identified worst-case scenarios, more than half of the total Zn and Cu and 14% of As can be expected to remobilize from the treated soil. The leaching procedure concerning sample agitation and type of filtration showed to substantially affect the results of As leaching, especially in OM rich soil.
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