| 1. |
- Rämö, Robert, et al.
(författare)
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Sediment Remediation Using Activated Carbon: Effects of Sorbent Particle Size and Resuspension on Sequestration of Metals and Organic Contaminants.
- 2022
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Ingår i: Environmental toxicology and chemistry. - : Wiley. - 1552-8618 .- 0730-7268. ; 41:4, s. 1096-1110
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Tidskriftsartikel (refereegranskat)abstract
- Thin-layer capping using activated carbon (AC) has been described as a cost-effective in situ sediment remediation method for organic contaminants. In this study, we compare the capping efficiency of powdered AC (PAC) against granular AC (GAC) using contaminated sediment from Oskarshamn harbor, Sweden. The effects of resuspension on contaminant retention and cap integrity were also studied. Intact sediment cores were collected from the outer harbor and brought to the laboratory. Three thin-layer caps, consisting of PAC or GAC mixed with clay, or clay only, were added to the sediment surface. Resuspension was created using a motor-driven paddle to simulate propeller wash from ship traffic. Passive samplers were placed in the sediment and in the water column to measure the sediment-to-water release of PAHs, PCBs, and metals. Our results show that a thin-layer cap with PAC reduced sediment-to-water fluxes of PCBs by 57 % under static conditions and 91 % under resuspension. Thin-layer capping with GAC was less effective than PAC, but reduced fluxes of high-molecular weight PAHs. Thin-layer capping with AC was less effective in retaining metals, except for Cd, which release was significantly reduced by PAC. Resuspension generally decreased water concentrations of dissolved cationic metals, perhaps due to sorption to suspended sediment particles. Sediment resuspension in treatments without capping increased fluxes of PCBs with log Kow > 7 and PAHs with log Kow 5 6, but resuspension reduced PCB and PAH fluxes through the PAC thin-layer cap. Overall, PAC performed better than GAC, but adverse effects on the benthic community and transport of PAC to non-target areas are drawbacks that favor the use of GAC. This article is protected by copyright. All rights reserved.© 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
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| 2. |
- Eivazihollagh, Alireza, et al.
(författare)
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On chelating surfactants : Molecular perspectives and application prospects
- 2019
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Ingår i: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322 .- 1873-3166. ; 278, s. 688-705
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Tidskriftsartikel (refereegranskat)abstract
- Chelating agents, molecules that very strongly coordinates certain metal ions, are used industrially as well as in consumer products to minimize disturbances and increase performance of reactions and applications. The widely used sequestering agents, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) belong to this branch of readily water-soluble compounds. When these chemical structures also have hydrophobic parts, they are prone to adsorb at air-water interfaces and to self-assemble. Such bifunctional molecules can be called chelating surfactants and will have more extended utilization prospects than common chelating agents or ordinary ionic surfactants. The present review attempts to highlight the fundamental behavior of chelating surfactants in solution and at interfaces, and their very specific interactions with metal ions. Methods to recover chelating surfactants from metal chelates are also described. Moreover, utilization of chelating surfactants in applications for metal removal in environmental engineering and mineral processing, as well as for metal control in the fields of biology, chemistry and physics, is exemplified and discussed.
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| 3. |
- Åkesson, Sofia, et al.
(författare)
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Characterizing natural degradation of tetrachloroethene (PCE) using a multidisciplinary approach
- 2020
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Ingår i: Ambio: a Journal of the Human Environment. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 50, s. 1074-1088
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Tidskriftsartikel (refereegranskat)abstract
- A site in mid-western Sweden contaminated with chlorinated solvents originating from a previous dry cleaning facility, was investigated using conventional groundwater analysis combined with compound-specific isotope data of carbon, microbial DNA analysis, and geoelectrical tomography techniques. We show the value of this multidisciplinary approach, as the different results supported each interpretation, and show where natural degradation occurs at the site. The zone where natural degradation occurred was identified in the transition between two geological units, where the change in hydraulic conductivity may have facilitated biofilm formation and microbial activity. This observation was confirmed by all methods and the examination of the impact of geological conditions on the biotransformation process was facilitated by the unique combination of the applied methods. There is thus significant benefit from deploying an extended array of methods for these investigations, with the potential to reduce costs involved in remediation of contaminated sediment and groundwater.
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| 4. |
- Sandhi, Arifin, 1986-, et al.
(författare)
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Phytofiltration of arsenic by aquatic moss (Warnstorfia fluitans)
- 2017
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424.
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Tidskriftsartikel (refereegranskat)abstract
- This work investigates whether aquatic moss (Warnstorfia fluitans) originating from an arsenic (As)-contaminated wetland close to a mine tailings impoundment may be used for phytofiltration of As. The aim was to elucidate the capacity of W. fluitans to remove As from arsenite and arsenate contaminated water, how nutrients affect the As uptake and the proportion of As adsorption and absorption by the moss plant, which consists of dead and living parts.Arsenic removal from 0, 1, or 10% Hoagland nutrient solution containing 0–100 μM arsenate was followed over 192 h, and the total As in aquatic moss after treatment was analysed. The uptake and speciation of As in moss cultivated in water containing 10 μM arsenate or arsenite were examined as As uptake in living (absorption + adsorption) and dead (adsorption) plant parts.Results indicated that W. fluitans removed up to 82% of As from the water within one hour when 1 μM arsenate was added in the absence of nutrients. The removal time increased with greater nutrient and As concentrations. Up to 100 μM As had no toxic effect on the plant biomass. Both arsenite and arsenate were removed from the solution to similar extents and, independent of the As species added, more arsenate than arsenite was found in the plant. Of the As taken up, over 90% was firmly bound to the tissue, a possible mechanism for resisting high As concentrations. Arsenic was both absorbed and adsorbed by the moss, and twice as much As was found in living parts as in dead moss tissue. This study revealed that W. fluitans has potential to serve as a phytofilter for removing As from As-contaminated water without displaying any toxic effects of the metalloid.
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| 5. |
- Önneby, Karin
(författare)
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Bioaugmentation for reduction of diffuse pesticide contamination : a bioprophylactic concept
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Pesticides and their residues frequently contaminate surface waters and groundwater so consequently there is a great need to identify methods and practices that reduce such contamination. This thesis examined the potential of a 'bioprophylactic' concept based on the hypothesis that diffuse contamination after application in the field can be significantly reduced if pesticides are degraded as rapidly as possible after the intended effect has been achieved. This involves adding pesticide degraders together with the pesticide at the time of application. Such enhanced degradation is particularly important for pesticides used on non-agricultural soils with low degradation and high leaching potential (e.g. roadsides, railway embankments, paths, farmyards, urban land). The herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA) was used as a model herbicide in this thesis, together with its degrader Sphingobium sp. T51. Soil inoculation with Sphingobium sp. T51 in microcosms significantly enhanced the degradation of MCPA compared with an uninoculated soil, without losing the herbicidal effect. In sand, 105 cells g-1 dry weight of soil reduced the MCPA concentration by 79-86% within one day, while only 0-31% reduction was observed in the uninoculated control after three days. However, Sphingobium sp. T51 needs to be formulated to retain its viability and degradation activity during prolonged storage and also for protection from the harsh environmental stresses associated with its application and functioning in the field. Both freeze drying and fluidised bed drying of Sphingobium sp. T51 resulted in high initial cell survival rates, of 67-85%. The storage stability of formulated Sphingobium sp. T51 was dependent on the formulation excipient/carrier used, storage temperature and atmospheric conditions. Sphingobium sp. T51 demonstrated approximately 50% survival in a freeze-dried sucrose formulation after six months of storage under partial vacuum at 25 °C. A fluidised bed-dried formulation with cottonseed flour as carrier resulted in the highest MCPA degradation in microcosms, but the storage stability was insufficient. Formulated and long-term stored Sphingobium sp. T51 reduced pesticide leaching by 85-94% of the total amount added in sand columns. Future research needs regarding practical implementation of the concept are discussed.
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| 6. |
- Santos, Graziely Cristina, 1983-, et al.
(författare)
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Comparative Analysis of Azo Dye Biodegradation by Aspergillus oryzae and Phanerochaete chrysosporium
- 2014
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Ingår i: Water, Air and Soil Pollution. - : Springer Science and Business Media LLC. - 0049-6979 .- 1573-2932. ; 225:7
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Tidskriftsartikel (refereegranskat)abstract
- The textile industry often releases effluents into the environment without proper treatment or complete dye removal. Azo dyes, which are characterized by azo groups (―N═N―), are frequently used in the textile industry. Among the different wastewater treatment methods available, biological treatment has been extensively studied. The aim of the present study was to compare the biodegradation of the azo dye Direct Blue 71 by the fungi Phanerochaete chrysosporium and Aspergillus oryzae in paramorphogenic form using a 100 μg/ml dye solution. Biodegradation tests were performed within 240 h. The absorbance values obtained with UV-VIS spectrophotometry were used to determine the absorbance ratio and the percentage of dye discoloration following the biodegradation test. FTIR analysis allowed the identification of molecular compounds in the solution before and after biodegradation. Both A. oryzae and P. chrysosporium demonstrated considerable potential regarding the biodegradation of dyes in wastewater. These results may contribute toward improving effluent treatment systems in the textile industry.
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| 7. |
- Anbalagan, Anbarasan, 1988-
(författare)
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A passage to wastewater nutrient recovery units : Microalgal-Bacterial bioreactors
- 2018
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Konstnärligt arbete (övrigt vetenskapligt/konstnärligt)abstract
- In recent years, the microalgal–bacterial process has been considered to be a very attractive engineering solution for wastewater treatment. However, it has not been widely studied in the context of conventional wastewater treatment design under Swedish conditions. The technology holds several advantages: as a CO2 sink, ability to withstand cold conditions, ability to grow under low light, fast settling without chemical precipitation, and reducing the loss of valuable nutrients (CO2, N2, N2O, PO4). The process also provides the option to be operated either as mainstream (treatment of municipal wastewater) or side stream (treatment of centrate from anaerobic digesters) to reduce the nutrient load of the wastewater. Furthermore, the application is not only limited to wastewater treatment; the biomass can be used to synthesise platform chemicals or biofuels and can be followed by recovery of ammonium and phosphate for use in agriculture.In the present study, the feasibility of applying the process in Swedish temperature and light conditions was investigated by implementing microalgae within the activated sludge process. In this context, the supporting operational and performance indicators (hydraulic retention time (HRT), sludge retention time (SRT) and nutrients removal) were evaluated to support naturally occurring consortia in photo-sequencing and continuous bioreactor configuration. Furthermore, CO2 uptake and light spectrum-mediated nutrient removal were investigated to reduce the impact on climate and the technical challenges associated with this type of system.The results identified effective retention times of 6 and 4 days (HRT = SRT) under limited lighting to reduce the electrical consumption. From the perspective of nitrogen removal, the process demands effective CO2 input either in the mainstream or side stream treatment. The incorporation of a vertical absorption column demonstrated effective CO2 mass transfer to support efficient nitrogen and phosphorus removal as a side stream treatment. However, the investigation of a continuous single-stage process as the mainstream showed a requirement for a lower SRT in comparison to semi-continuous operation due to faster settlability, regardless of inorganic carbon. Furthermore, the process showed an effective reduction of influent phosphorus and organic compounds (i.e. COD/TOC) load in the wastewater as a result of photosynthetic aeration. Most importantly, the operation was stable at the temperature equivalent of wastewater (12 and 13 ˚C), under different lighting (white, and red-blue wavelengths) and retention times (6 and 1.5 d HRT) with complete nitrification. Additionally, the biomass production was stable with faster settling properties without any physiochemical separation.The outcomes of this thesis on microalgal–bacterial nutrient removal demonstrates that (1) photosynthesis-based aeration at existing wastewater conditions under photo-sequential and continuous photobioreactor setup, (2) flocs with rapid settling characteristics at all studied retention times, (3) the possibility of increasing carbon supplementation to achieve higher carbon to nitrogen balance in the photobioreactor, and (4) most importantly, nitrification-based microalgal biomass uptake occurred at all spectral distributions, lower photosynthetic active radiation and existing wastewater conditions.
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| 8. |
- Bonaglia, Stefano, et al.
(författare)
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Capping with activated carbon reduces nutrient fluxes, denitrification and meiofauna in contaminated sediments
- 2019
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 148, s. 515-525
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Tidskriftsartikel (refereegranskat)abstract
- Sediment capping with activated carbon (AC) is an effective technique used in remediation of contaminated sediments, but the ecological effects on benthic microbial activity and meiofauna communities have been largely neglected. This study presents results from a 4-week experiment investigating the influence of two powdered AC materials (bituminous coal-based and coconut shell-derived) and one control material (clay) on biogeochemical processes and meiofauna in contaminated sediments. Capping with AC induced a 62‒63% decrease in denitrification and a 66‒87 % decrease in dissimilatory nitrate reduction to ammonium (DNRA). Sediment porewater pH increased from 7.1 to 9.0 and 9.7 after addition of bituminous AC and biomass-derived AC, respectively. High pH (>8) persisted for at least two weeks in the bituminous AC and for at least 24 days in the coconut based AC, while capping with clay had no effect on pH. We observed a strong impact (nitrate fluxes being halved in presence of AC) on nitrification activity as nitrifiers are sensitive to high pH. This partly explains the significant decrease in nitrate reduction rates since denitrification was almost entirely coupled to nitrification. Total benthic metabolism estimated by sediment oxygen uptake was reduced by 30 and 43 % in presence of bituminous coal-based AC and coconut shell-derived AC, respectively. Meiofauna abundances decreased by 60‒62 % in the AC treatments. Taken together, these observations suggest that AC amendments deplete natural organic carbon, intended as food, to heterotrophic benthic communities. Phosphate efflux was 91 % lower in presence of bituminous AC compared to untreated sediment probably due to its content of aluminum (Al) oxides, which have high affinity for phosphate. This study demonstrates that capping with powdered AC produces significant effects on benthic biogeochemical fluxes, microbial processes and meiofauna abundances, which are likely due to an increase in porewater pH and to the sequestration of natural, sedimentary organic matter by AC particles.
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| 9. |
- Gentili, Francesco, et al.
(författare)
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Algal cultivation in urban wastewater : an efficient way to reduce pharmaceutical pollutants
- 2017
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Ingår i: Journal of Applied Phycology. - : Springer Science and Business Media LLC. - 0921-8971 .- 1573-5176. ; 29:1, s. 255-262
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to investigate whether pharmaceutical pollutants in urban wastewater can be reduced during algal cultivation. A mixed population of wild freshwater green algal species was grown on urban wastewater influent in a 650 L photobioreactor under natural light and with the addition of flue gases. Removal efficiencies were very high (> 90 %), moderate (50-90 %), low (10-50 %), and very low or non-quantifiable (< 10 %) for 9, 14, 11, and 18 pharmaceuticals, respectively, over a 7-day period. High reduction was found in the following pharmaceuticals: the beta-blockers atenolol, bispropol, and metoprolol; the antibiotic clarithromycine; the antidepressant bupropion; the muscle relaxant atracurium; hypertension drugs diltiazem and terbutaline used to relive the symptoms of asthma. Regression analysis did not detect any relationship between the reduction in pharmaceutical contents and light intensity reaching the water surface of the algal culture. However, the reduction was positively correlated with light intensity inside the culture and stronger when data collected during the night were excluded. Algae cultivation can remove partially or totally pharmaceutical pollutants from urban wastewater, and this opens up new possibilities for treating urban wastewater.
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| 10. |
- Pondja, Estevao
(författare)
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Environmental aspects of coal mine drainage: a regional study of Moatize in Mozambique
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mozambique is one of the largest coal producers in Africa. Extraction of the coal is carried out in the Moatize district of the Tete province in the center of the country. A surface mining technique is used to extract the coal below ground level. During mining activities, sulfide minerals, which are commonly associated with coal, are exposed to oxygen and water, leading to the generation of acid mine drainage (AMD). AMD is high in acidity and has a high content of metals, metalloids and sulfate that can cause severe damage to the environment. Moatize is inside the lower Zambezi River basin, the pollution that occurs there due to mining activities constituting a risk both for public health and for the water resources. The standard guidelines in Mozambique for wastewater from coal mining are very weak, allowing the coal mining companies to pollute considerably. The prevention, containment and remediation of polluted mine water are measures that should be carried out to avoid the spread of pollution. Prevention is the least expensive strategy, but it cannot always prevent the generation of polluted mine water. Thus containment and treatment need to be put into practice. Both active and passive treatment are used to treat polluted mine water. Since Moatize is a largely unstudied area, both static and leaching tests were carried out to investigate the possibility of AMD being generated. The geochemical processes that could impact on the quality of mine drainage stemming from the waste rock there were assessed. Use of cost-effective methods for the treatment of mine water by use of bioremediation coupled with adsorption, using cassava peels that are readily available in the country as a carbon source and as an adsorbent is proposed. Since climate changes and climate variability can exacerbate the negative impact of surface mining, the possibility of this was assessed. It was found that the production of AMD was likely in at least one of the coal mines in Moatize. The mine water from coal mines in Moatize was found to have a high content of sulfate, calcium, magnesium and manganese. A set of guidelines for coal mine effluents that was developed, based on different guidelines obtained from around the world, was proposed for Mozambique. Sulfate reducing bacteria coupled with adsorption appeared to be appropriate for removing these pollutants. Cassava peels used as adsorbents appeared to be effective in removing calcium, magnesium and manganese. Based on climate data, the period from November on through February was found to be the period in which the pollution load in Moatize was greatest. Since the flow rate in the Revúbué River, which is close to the coal mines, is highly dependent upon the precipitation that occurs during the rainy season, the discharge of polluted mine water should be avoided. To achieve sustainable mining in Moatize, the coal mining companies, the regulators and the stakeholders from water sector there need to work together. A framework for integrating efforts to satisfy the needs of the different stakeholders involved in the water sector in Moatize was proposed.
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