| 1. |
- Antelo, Juan, et al.
(författare)
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Stability of naturally occurring AMD–schwertmannite in the presence of arsenic and reducing agents
- 2021
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Ingår i: Journal of Geochemical Exploration. - : Elsevier. - 0375-6742 .- 1879-1689. ; 220
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Tidskriftsartikel (refereegranskat)abstract
- Secondary iron oxides formed in acid mine drainage, such as schwertmannite, are scavengers for metal(loid)s in mining environments. Increasing the understanding of the geochemical transformations of these minerals, as well as knowing how metal(loid)s affect these transformations, is crucial to ultimately predict the fate of these trace elements in acidic mine drainage and to minimize the potential environmental risk. In this study, transformation experiments have been conducted with a schwertmannite-rich sediment collected from a mining area and with synthesized schwertmannite as a reference material. The transformation of schwertmannite into goethite was studied as a function of the presence of arsenic, pH value, and redox conditions. Arsenic delayed the mineral transformation from pseudo-stable amorphous phases to more stable crystalline forms, especially at higher arsenic loadings and more acidic pH. Experiments in the presence of Fe(II) and ascorbic acid have proven that both components promote the mineral transformation or reductive dissolution of schwertmannite under anoxic conditions. The presence of arsenic reduced the catalytic effect of Fe(II), stabilizing the schwertmannite particles. On the other hand, arsenic had no effect on the reductive dissolution at these conditions when ascorbic acid was used as a reducing agent. © 2020 Elsevier B.V.
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| 2. |
- Gusiatin, Zygmunt Mariusz, et al.
(författare)
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Remediation of smelter contaminated soil by sequential washing using biosurfactants
- 2021
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI. - 1661-7827 .- 1660-4601. ; 18:24
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents experimental results from the use of biosurfactants in the remediation of a soil from a smelter in Poland. In the soil, concentrations of Cu (1659.1 mg/kg) and Pb (290.8 mg/kg) exceeded the limit values. Triple batch washing was tested as a soil treatment. Three main variants were used, each starting with a different plant-derived (saponin, S; tannic acid, T) or microbial (rhamnolipids, R) biosurfactant solution in the first washing, followed by 9 different sequences using combinations of the tested biosurfactants (27 in total). The efficiency of the washing was determined based on the concentration of metal removed after each washing (CR), the cumulative removal efficiency (Ecumulative) and metal stability (calculated as the reduced partition index, Ir, based on the metal fractions from BCR sequential extraction). The type of biosurfactant sequence influenced the CR values. The variants that began with S and R had the highest average Ecumulative for Cu and Pb, respectively. The Ecumulative value correlated very strongly (r > 0.8) with the stability of the residual metals in the soil. The average Ecumulative and stability of Cu were the highest, 87.4% and 0.40, respectively, with the S-S-S, S-S-T, S-S-R and S-R-T sequences. Lead removal and stability were the highest, 64–73% and 0.36–0.41, respectively, with the R-R-R, R-R-S, R-S-R and R-S-S sequences. Although the loss of biosurfactants was below 10% after each washing, sequential washing with biosurfactants enriched the soil with external organic carbon by an average of 27-fold (S-first variant), 24-fold (R first) or 19-fold (T first). With regard to environmental limit values, metal stability and organic carbon resources, sequential washing with different biosurfactants is a beneficial strategy for the remediation of smelter-contaminated soil with given properties.
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| 3. |
- Johansson, Kim, et al.
(författare)
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Immobilisation of arsenic in contaminated soil by electrokinetics in an outdoor experiment
- 2024
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Ingår i: Science of the Total Environment. - : Elsevier B.V.. - 0048-9697 .- 1879-1026. ; 918
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Tidskriftsartikel (refereegranskat)abstract
- Although landfilling is environmentally and economically unsustainable, it is the dominant soil remediation method in EU member states. This paper describes part of a study on mixed contaminants that investigated the stabilisation of arsenic (As) in contaminated soil in an outdoor box experiment with electrokinetic treatment (EK). The experiment was conducted in two 1 m3 boxes, each containing a 20 cm bottom layer of sand, overlaid with 20 cm of peat. In EK, a pulsating, low-voltage current was applied with the intention of corroding the zerovalent iron (Fe) electrodes, migrating ionic Fe species, and forming secondary iron minerals, thereby immobilizing As. Porewater samples were collected over two seasons to determine whether the treatment decreased the concentration of dissolved As. Sequential extraction was performed on the soil samples to determine whether the fraction of Fe-bound As increased. Reed canary grass was planted in one of the boxes during the second season and analysed for As uptake. The results showed that the treatment decreased the porewater As concentration in sand by 50–54 %, while the concentration of Fe increased. The sequential extraction of sand showed that the fraction of As bound to poorly crystalline Fe oxides increased during this time. This treatment effect was less visible in the peat. Moreover, the exchangeable As fraction increased in both peat and sand, most likely because of the decrease in redox potential at the end of the experiment. The plants grown in treated soil accumulated less As than those grown in untreated soil, indicating that the phytoavailable As fraction decreased. This study showed that EK remediation can be a suitable in situ remediation technique, mostly in sand. Future research should focus on redox control to further optimise EK remediation and ensure long-term As stability in treated soils.
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| 4. |
- Kasiuliene, Alfreda, et al.
(författare)
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Leaching of metal(loid)s from ashes of spent sorbent and stabilisation effect of calcium-rich additives
- 2020
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Ingår i: Environmental Science and Pollution Research. - : Springer. - 0944-1344 .- 1614-7499. ; 27:23, s. 29248-29256
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Tidskriftsartikel (refereegranskat)abstract
- Contaminated water with multiple contaminants, including As, Cr, Cu and Zn, was treated with a sorbent prepared by coating peat with Fe oxides. Because As has a relatively little explored market, the regeneration of the spent sorbent was not feasible. Meanwhile, the disposal of As wastes in landfills can cause landfill leachate treatment problems. Under the reducing conditions prevailing at landfills, As(V) is reduced to As(III), which is a toxic and more mobile form. In this study, incineration was explored as a management option to treat the spent sorbent that was loaded with As, Cr, Cu and Zn. The first objective of this study was to evaluate the leaching of these metal(loid)s from the ashes and compare it with the leaching from the spent sorbents before incineration. The second objective was to evaluate the leaching behaviour when the spent sorbent was co-incinerated with a Ca-rich additive (lime). To achieve these objectives, the obtained ashes were subjected to leaching tests, sequential extraction, and X-ray diffraction analyses. After the incineration, the ash content ranged from 9 to 19% of the initial mass of the spent sorbents. The leaching of As, Cu and Zn decreased compared with that from the spent sorbents before the thermal treatment because of the high incineration temperatures and/or co-incineration with lime. However, the leaching of Cr increased, which would hinder the disposal of the obtained ashes in a landfill because the limit value for disposal at a landfill for hazardous wastes was exceeded by 50 times. However, co-incineration with 10 wt% lime significantly decreased the leaching of Cr as a result of the formation of water-insoluble Ca-Cr compounds.
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| 5. |
- Kumpiene, Jurate, et al.
(författare)
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Arsenic immobilisation in soil using electricity-induced spreading of iron in situ
- 2023
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Ingår i: Journal of Environmental Management. - : Elsevier. - 0301-4797 .- 1095-8630. ; 325:Part A
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Tidskriftsartikel (refereegranskat)abstract
- An in situ method for spreading iron amendments to arsenic (As)-contaminated soil has been investigated in the laboratory and field. This study tested the distribution of Fe from corroding electrodes through soil using a low-voltage direct current in a laboratory setting and validated the method in the field for As immobilisation in contaminated soil. Laboratory tests revealed that the corrosion of Fe electrodes in soil occurred in a way similar to that during the Fe electrocoagulation in water, which decreased the As concentrations in flow-through water from 150 μg L−1 to undetectable levels. Method validation over one year in the field using electric current pulses with reversing polarity revealed a decrease in As concentration in groundwater by 72–97% in five of the six groundwater wells within the experimental area. This method of introducing Fe amendments to soil can reduce the need for soil excavation upon chemical immobilisation of contaminants in soil.
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| 6. |
- Kumpiene, Jurate, et al.
(författare)
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LONG-TERM stability of arsenic in iron amended contaminated soil
- 2021
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Ingår i: Environmental Pollution. - : Elsevier. - 0269-7491 .- 1873-6424. ; 269
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed at elucidating the long-term efficiency of soil remediation where chemical stabilization of arsenic (As) contaminated soil using zerovalent iron (Fe) amendments was applied. A combination of chemical extraction and extended X-Ray absorption fine structure (EXAFS) spectroscopy technique was applied on soils collected from five laboratory and field experiments in Sweden and France. All soils were treated with 1 wt% of zerovalent Fe grit 2–15 years prior to the sampling. The results indicate that all studied soils, despite the elapsed time since their amendment with Fe grit, had substantial amounts of ferrihydrite and/or lepidocrocite. These metastable and the most reactive Fe (oxyhydr)oxides (mainly ferrihydrite) were still present in substantial amounts even in the soil that was treated 15 years prior to the sampling and contributed most to the As immobilisation in the amended soils. This increases confidence in the long-term efficiency of As immobilisation using zerovalent Fe amendments. Both applied methods, sequential extraction and EXAFS, were in line for most of the samples in terms of their ability to highlight As immobilisation by poorly crystalline Fe phases.
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| 7. |
- Kumpiene, Jurate, et al.
(författare)
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Roads with underlying tar asphalt - spreading, bioavailability and toxicity of their polycyclic aromatic hydrocarbons
- 2021
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Ingår i: Environmental Pollution. - : Elsevier. - 0269-7491 .- 1873-6424. ; 289
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Tidskriftsartikel (refereegranskat)abstract
- Some of the older Swedish roads contain road tar underneath a surface layer of bituminous asphalt. This road tar, also known as tar asphalt, contains large amounts of polycyclic aromatic hydrocarbons (PAHs). There is concern about PAHs spreading from the bottom layers of these older roads to the surrounding environment, and that because of this spreading road tar asphalt should not be recycled but rather placed in landfills. However, a risk assessment of PAH spreading below roads has not yet been conducted. The first aim of this study was to assess this potential spreading of PAHs from underlying tar asphalt to the sand beneath, the soil next to the roads, as well as nearby groundwater. The second aim was to measure the bioavailability and estimate the toxicity of PAHs in all relevant media using polyoxymethylene (POM) passive samplers. Four road sections and nearby groundwater in northern Sweden were investigated, including a control road without tar asphalt. PAHs were detected in all analysed solid media at varying concentrations: in asphalt from 2.3 to 4800 mg kg−1, in underlying sand from <1.5 to 460 mg kg−1 and in slope soil from <1.5 to 36 mg kg−1. However, the spread of PAHs from the asphalt to roadside soil and groundwater was very limited. Groundwater at most of the road sections contained very low or non-detectable levels of PAHs (<0.08–0.53 μg L−1, excluding one site where fuel contamination is hypothesized). The PAHs generally showed low bioavailability. Only asphalt with PAH content >1200 mg kg−1 exhibited bioavailable concentrations that exceeded threshold concentrations for serious risk. The most PAH contaminated sand and soil samples exhibited low toxicity when considering bioavailability, only in some cases exceeding chronic toxicity threshold concentrations. These results were compared with the Swedish EPA's guideline values for PAH in contaminated soil, which is shown to overpredict toxicity for these sites. Further research on the leaching and transportation processes of PAHs from subsurface tar asphalt is recommended for developing risk analysis approaches.
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| 8. |
- Larsson, Martin Oscar, et al.
(författare)
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Evaluation and modelling of polycyclic aromatic hydrocarbon (PAH) bioavailability in soils affected by coal tar asphalt
- 2024
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Ingår i: Environmental Pollution. - : Elsevier. - 0269-7491 .- 1873-6424. ; 359
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Tidskriftsartikel (refereegranskat)abstract
- There are large masses of coal tar asphalt present in old roads, containing high concentrations of polycyclic aromatic hydrocarbons (PAHs). Uncertainty surrounding the risk they pose causes problems during road reconstruction and for the reuse of the asphalt present. To help elucidate potential risks, a parsimonious linear equilibrium partitioning model for the bioavailability of PAHs in soils contaminated by tar asphalt particles was developed. Furthermore, a set of partitioning coefficients for PAHs between sampled coal tar binders and water were determined experimentally, as well as measurements of freely dissolved concentrations using polyoxymethylene samplers in batch tests and column recirculation experiments with various mixtures of different soils (peat and sandy loam) and tar asphalts. The model predictions of freely dissolved concentrations were conservative and within an order of magnitude of measurements in both batch and column tests. The model presented here only relies on soil organic carbon content and the fraction coal tar binder in the soil to model PAH partitioning. This model could be used for more realistic. Low tier risk assessments towards rational prioritization of sensitive areas for risk reduction efforts.
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| 9. |
- Lázaro, Carlos, et al.
(författare)
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Thermal Transformation of Natural Schwertmannite in the Presence of Chromium
- 2022
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Ingår i: Minerals. - : MDPI. - 2075-163X. ; 12:6
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Tidskriftsartikel (refereegranskat)abstract
- Schwertmannite is a metastable mineral playing a crucial role in the immobilization of metal(oid)s in acid mine drainage (AMD) systems. High temperatures associated with wildfires could lead to a sudden schwertmannite transformation, changing the mobility of metal(oid)s. The objective of the present study was to examine the thermal transformation from schwertmannite to hematite, and the subsequent effect on the chromium partitioning. The immobilization of arsenate after thermal transformation and its implications on chromium mobility was also evaluated. Natural schwertmannite, with increasing contents of chromium, was thermally treated between 200 to 800 °C. Transformation products were characterized by solid-phase techniques and selective chemical extractions. Results indicated a transformation to hematite at temperatures above 400 °C. The presence of chromium barely affected the temperature at which the transformation occurred, although partitioning of chromium in the mineral changed with temperature. As the temperature increased from 25 °C to 400 °C, chromium was less mobile and less outcompeted by arsenic adsorption, suggesting a larger contribution of inner-sphere complexes with increasing temperature. At temperatures above 600 °C, non-mobile forms strongly associated with neo-formed hematite were found. Finally, neo-formation of hematite led to a decrease in arsenic adsorption, implying a potentially enhanced arsenic mobility in AMD systems upon wildfires.
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| 10. |
- Ren, Zhongfei, et al.
(författare)
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Combination of adsorption/desorption and photocatalytic reduction processes for PFOA removal from water by using an aminated biosorbent and a UV/sulfite system
- 2023
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Ingår i: Environmental Research. - : Elsevier. - 0013-9351 .- 1096-0953. ; 228
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Tidskriftsartikel (refereegranskat)abstract
- Per- and polyfluoroalkyl substances (PFAS) are stable organic chemicals, which have been used globally since the 1940s and have caused PFAS contamination around the world. This study explores perfluorooctanoic acid (PFOA) enrichment and destruction by a combined method of sorption/desorption and photocatalytic reduction. A novel biosorbent (PG-PB) was developed from raw pine bark by grafting amine groups and quaternary ammonium groups onto the surface of bark particles. The results of PFOA adsorption at low concentration suggest that PG-PB has excellent removal efficiency (94.8%–99.1%, PG-PB dosage: 0.4 g/L) to PFOA in the concentration range of 10 μg/L to 2 mg/L. The PG-PB exhibited high adsorption efficiency regarding PFOA, being 456.0 mg/g at pH 3.3 and 258.0 mg/g at pH 7 with an initial concentration of 200 mg/L. The groundwater treatment reduced the total concentration of 28 PFAS from 18 000 ng/L to 9900 ng/L with 0.8 g/L of PG-PB. Desorption experiments examined 18 types of desorption solutions, and the results showed that 0.05% NaOH and a mixture of 0.05% NaOH + 20% methanol were efficient for PFOA desorption from the spent PG-PB. More than 70% (>70 mg/L in 50 mL) and 85% (>85 mg/L in 50 mL) of PFOA were recovered from the first and second desorption processes, respectively. Since high pH promotes PFOA degradation, the desorption eluents with NaOH were directly treated with a UV/sulfite system without further adjustment. The final PFOA degradation and defluorination efficiency in the desorption eluents with 0.05% NaOH + 20% methanol reached 100% and 83.1% after 24 h reaction. This study proved that the combination of adsorption/desorption and a UV/sulfite system for PFAS removal is a feasible solution for environmental remediation.
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| 11. |
- Uwayezu, Jean Noel, et al.
(författare)
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Combination of separation and degradation methods after PFAS soil washing
- 2023
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Ingår i: Science of the Total Environment. - : Elsevier. - 0048-9697 .- 1879-1026. ; 907
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Tidskriftsartikel (refereegranskat)abstract
- The current study evaluated a three-stage treatment to remediate PFAS-contaminated soil. The treatment consisted of soil washing, foam fractionation (FF), and electrochemical oxidation (EO). The possibility of replacing the third stage, i.e., EO, with an adsorption process was also assessed. The contamination in the studied soils was dominated by perfluorooctane sulfonate (PFOS), with a concentration of 760 and 19 μg kg−1 in soil I and in soil II, accounting for 97 % and 70 % of all detected per-and polyfluoroalkyl substances (PFAS). Before applying a pilot treatment of soil, soil washing was performed on a laboratory scale, to evaluate the effect of soil particle size, initial pH and a liquid-to-soil ratio (L/S) on the leachability of PFAS. A pilot washing system generated soil leachate that was subsequently treated using FF and EO (or adsorption) and then reused for soil washing. The results indicated that the leaching of PFAS occurred easier in 0.063–1 mm particles than in the soil particles having a size below 0.063 mm. Both alkaline conditions and a continual replacement of the leaching solution increased the leachability of PFAS. The analysis using one-way ANOVA showed no statistical difference in means of PFOS washed out in laboratory and pilot scales. This allowed estimating twenty washing cycles using 120 L water to reach 95 % PFOS removal in 60 kg soil. The aeration process removed 95–99 % PFOS in every washing cycle. The EO and adsorption processes achieved similar results removing up to 97 % PFOS in concentrated soil leachate. The current study demonstrated a multi-stage treatment as an effective and cost-efficient method to permanently clean up PFAS-contaminated soil.
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| 12. |
- Uwayezu, Jean Noel, et al.
(författare)
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Combining electrochemistry and ultraviolet radiation for the degradation of per- and poly-fluoroalkyl substances in contaminated groundwater and wastewater
- 2023
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Ingår i: Journal of Water Process Engineering. - : Elsevier. - 2214-7144. ; 54
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical and ultraviolet-based methods are advanced oxidation processes emerging as viable water and wastewater treatment options. In this study, a combination of these two methods (EO-UV) using boron-doped diamond (BDD) electrodes and ultraviolet radiation at both 185 and 254 nm was assessed for the degradation of poly-fluoroalkyl substances (PFAS). Sodium persulfate (Na2S2O8) and sodium sulfate (Na2SO4) were used as electrolytes. The method was investigated on model solutions containing perfluorooctanoic acid (PFOA) and perfluorosulfonic acid (PFOS). The method's effectiveness was assessed by comparing PFAS removal efficiencies and energy demands associated with the use of separate and combined treatments. The results showed that the highest removal of PFOA and PFOS was 96 % and 85 % respectively, which was achieved using EO-UV and persulfate electrolytes. Average removal efficiencies were 1.5–2 times higher in EO-UV than in EO and 4–6 times higher than in UV treatment. The degradation of PFAS under EO-UV and persulfate applied to PFAS-contaminated groundwater and wastewater reached 94 % PFOA and 88 % PFOS in groundwater and 51 % and 63 % in wastewater. The removal of the sum of eleven PFAS was 86 % and 66 % in groundwater and wastewater, respectively. The combination of EO, UV and persulfate was the most effective option for PFAS treatment at lower energy consumption.
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| 13. |
- Uwayezu, Jean Noel, et al.
(författare)
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Electrochemical degradation of per- and poly-fluoroalkyl substances using boron-doped diamond electrodes
- 2021
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Ingår i: Journal of Environmental Management. - : Elsevier. - 0301-4797 .- 1095-8630. ; 290
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Tidskriftsartikel (refereegranskat)abstract
- Electrochemical degradation using boron-doped diamond (BDD) electrodes has been proven to be a promising technique for the treatment of water contaminated with per- and poly-fluoroalkyl substances (PFAS). Various studies have demonstrated that the extent of PFAS degradation is influenced by the composition of samples and electrochemical conditions. This study evaluated the significance of several factors, such as the current density, initial concentration of PFAS, concentration of electrolyte, treatment time, and their interactions on the degradation of PFAS. A 24 factorial design was applied to determine the effects of the investigated factors on the degradation of perfluorooctanoic acid (PFOA) and generation of fluoride in spiked water. The best-performing conditions were then applied to the degradation of PFAS in wastewater samples. The results revealed that current density and time were the most important factors for PFOA degradation. In contrast, a high initial concentration of electrolyte had no significant impact on the degradation of PFOA, whereas it decreased the generation of F−. The experimental design model indicated that the treatment of spiked water under a current density higher than 14 mA cm−2 for 3–4 h could degrade PFOA with an efficiency of up to 100% and generate an F− fraction of approximately 40–50%. The observed high PFOA degradation and a low concentration of PFAS degradation products indicated that the mineralization of PFOA was effective. Under the obtained best conditions, the degradation of PFOA in wastewater samples was 44–70%. The degradation efficiency for other PFAS in these samples was 65–80% for perfluorooctane sulfonic acid (PFOS) and 42–52% for 6–2 fluorotelomer sulfonate (6-2 FTSA). The presence of high total organic carbon (TOC) and chloride contents was found to be an important factor affecting the efficiency of PFAS electrochemical degradation in wastewater samples. The current study indicates that the tested method can effectively degrade PFAS in both water and wastewater and suggests that increasing the treatment time is needed to account for the presence of other oxidizable matrices.
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| 14. |
- Uwayezu, Jean Noel
(författare)
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Remediation of PFAS-contaminated soil and wastewater : Feasibility of chain treatment applying destructive techniques
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Per- and polyfluoroalkyl substances (PFAS) are man-made chemicals ubiquitously distributed in soil and aquatic media, resulting from their wide range of industrial applications. Today, PFAS is a global concern due to their persistence in the environment and their adverse effects on humans and the ecosystem. Despite the considerable efforts to develop PFAS treatment methods, a viable solution has not yet been established.This Ph.D. thesis investigated the potential of applying electrochemical oxidation (EO) and UV radiation assisted with persulfate (PS/UV), both individually and in combination(EO-UV), for PFAS degradation in solutions. Furthermore, integrating destructive technique showing the most promising results, i.e., EO, within a treatment chain comprising soil washing (SW) and foam fractionation (FF) was assessed to eliminate PFAS from contaminated soil. Perfluorooctanesulfonic acid (PFOS) accounted for 97% of the PFAS contamination in the soil. The EO and PS/UV showed the potential to break down PFAS in spiked solutions. Removal of 99 % perfluorooctanoic acid (PFOA) was found at a current density of 23.4 mA cm-2 and 4 h whereas 80% PFOA, 60% PFOS, and 57% perfluorobutanoic acid (PFBA) were removed in 4 h and in the presence of 5 g L-1 Na2S2O8. By transferring the best experimental conditions for the treatment of PFAS-contaminated wastewater, the removal of 56% ∑11PFAS was reached using EO whereas PS/UV led to an increase in the concentration of PFAS. It was highlighted that optimizing EO would lead to higher removal and reduce energy consumption. Nevertheless, PFAS removal from groundwater using PS/UV treatment was almost as effective as in synthetic solutions, highlighting its potential for treating PFAS in matrix-free water. Combining EO and UV led to substantial removal improvements due to degradation processes in both systems, probably due to synergistic effects. Adding FF to soil SW led to an average removal of 82% and 92% ∑11PFAS in soil and leachate respectively, at the L/S of 5 (five washing cycles) and pH 11.5. As per estimations, employing 20 treatment cycles could result in 94% and 91% of PFAS removal in soil and leachate. The EO at 60 mA cm-2 and 2 h removed 88.3% of ∑11PFAS, which was contained in wastewater resulting from the FF process. Overall, the SW-FF-EO three-stage treatment led to the removal of 67% ∑11PFAS, estimated to be 88% if the SW-FF consecutive treatments are repeated 20 times. Incorporating FF in the treatment chain enabled leachate recycling and reduced water volume needs in the soil treatment process, but also concentrated PFAS in a smaller water volume, thereby allowing the EO step to be more cost-effective.
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| 15. |
- Uwayezu, Jean Noel, et al.
(författare)
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Validation of UV/persulfate as a PFAS treatment of industrial wastewater and environmental samples
- 2023
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Ingår i: Journal of Water Process Engineering. - : Elsevier. - 2214-7144. ; 53
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Tidskriftsartikel (refereegranskat)abstract
- The contamination of natural water and industrial wastewater with per- and polyfluoroalkyl substances (PFAS) occurs globally. Thus, proper technologies are required to reduce PFAS in the environment and mitigate the adverse effects of these pollutants on human health and the environment. This study used a 23 full factorial design to evaluate the importance of operating factors including the level of persulfate (PS), the initial concentration of PFAS, and the time to the photochemical degradation of PFAS via ultraviolet irradiation at 185/254 nm assisted with persulfate (PS/UV method) in spiked solution. The method was then applied to break down PFAS in industrial wastewater, landfill leachate and groundwater samples using the highest factor levels applied in the 23 full factorial design. The results showed that the three investigated factors played an important role in the degradation of PFAS. The highest PFAS degradation was 57 % perfluorobutanoic acid (PFBA), 80 % perfluorooctanoic acid (PFOA) and 60 % perfluorooctane sulfonate (PFOS) using 10 mg L−1 PFAS, 5 g L−1 PS for 4 h. The defluorination also increased in the presence of PS but decreased in the presence of potassium hydrogen phthalate, nitrates, and chlorides. The PS/UV method decreased the concentration of PFAS in wastewater samples by 20–25 % PFOS and 13–15 % perfluorohexane sulfonate (PFHxS). PFAS degradation in wastewater improved with increasing treatment time. Under the PS/UV treatment, the degradation of major PFAS in groundwater was 94 % 6–2 FTS, 75 % PFOA, 62 % PFOS and 61 % PFHxS. The removal of major compounds in landfill leachate reached up to 12 % PFHxA, 32 % PFPeA, 56 % PFOA and 43 % PFOS. Our study indicated matrix effects leading to decreased PFAS degradation in different contaminated waters. The level of PS should also be controlled to an optimal value because higher levels led to a decrease in treatment efficiency.
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