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- Berglund, Björn, et al.
(author)
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Efficient removal of antibiotics in surface-flow constructed wetlands, with no observed impact on antibiotic resistance genes
- 2014
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In: Science of the Total Environment. - Amsterdam : Elsevier. - 0048-9697 .- 1879-1026. ; 476-477, s. 29-37
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Journal article (peer-reviewed)abstract
- Recently, there have been growing concerns about pharmaceuticals including antibiotics as environmental contaminants. Antibiotics of concentrations commonly encountered in wastewater have been suggested to affect bacterial population dynamics and to promote dissemination of antibiotic resistance. Conventional wastewater treatment processes do not always adequately remove pharmaceuticals causing environmental dissemination of low levels of these compounds. Using constructed wetlands as an additional treatment step after sewage treatment plants have been proposed as a cheap alternative to increase reduction of wastewater contaminants, however this means that the natural microbial community of the wetlands becomes exposed to elevated levels of antibiotics. In this study, experimental surface-flow wetlands in Sweden were continuously exposed to antibiotics of concentrations commonly encountered in wastewater. The aim was to assess the antibiotic removal efficiency of constructed wetlands and to evaluate the impact of low levels of antibiotics on bacterial diversity, resistance development and expression in the wetland bacterial community. Antibiotic concentrations were measured using liquid chromatography-mass spectrometry and the effect on the bacterial diversity was assessed with 16S rRNA-based denaturing gradient gel electrophoresis. Real-time PCR was used to detect and quantify antibiotic resistance genes and integrons in the wetlands, during and after the exposure period. The results indicated that the antibiotic removal efficiency of constructed wetlands was comparable to conventional wastewater treatment schemes. Furthermore, short-term treatment of the constructed wetlands with environmentally relevant concentrations (i.e. 100-2000 ng x 1(-1)) of antibiotics did not significantly affect resistance gene concentrations, suggesting that surface-flow constructed wetlands are well-suited for wastewater treatment purposes. (c) 2014 Elsevier B.V. All rights reserved.
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| 4. |
- Bodin, Hristina, et al.
(author)
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Attenuation of pharmaceutical substances : phytoremediation using constructed wetlands
- 2018
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In: 13th Society of Wetland Scientists (SWS) Europe Chapter Meeting. ; , s. 19-22
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Conference paper (other academic/artistic)abstract
- Introduction: Currently, wastewater treatment plants (WWTPs) do not efficiently remove pharmaceutical substances (PS). Thus, such substances are now frequently found in aquatic ecosystems worldwide. Also, concentrations of some PS in treated effluents exceed Environmental Quality Standards proposed by EU legislation. One resource-efficient option for increasing PS removal in WWTP effluents is to use constructed wetlands (CWs) as an attenuation step (Breitholtz et al. 2012; Li et al. 2014). However, very little research has been done on how to maximize the PS attenuation capacity of CWs. Therefore, a project with the aim to investigate reduction of different pharmaceutical substances in CWs with different vegetation compositions and water depths, was performed at the Experimental Wetland Area (EVA) located 20 km north of Halmstad, Sweden.
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| 5. |
- Bodin, Hristina, et al.
(author)
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Tracer behaviour and analysis of hydraulics in experimental free watersurface wetlands
- 2012
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In: Ecological Engineering. - Amsterdam : Elsevier BV. - 0925-8574 .- 1872-6992. ; 49, s. 201-211
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Journal article (peer-reviewed)abstract
- Effects of inlet design and vegetation type on tracer dynamics and hydraulic performance were investigated using lithium chloride in 18 experimental free water surface wetlands. The wetlands received similar water flow but had different vegetation types: 6 emergent vegetation wetlands (EVWs), 6 submerged vegetation wetlands (SVWs) and 6 free development wetlands (FDWs). Two types of inlet designs were applied: half of each wetland vegetation type had a barrier near the inlet to help distribute incoming tracer solution, while the rest had no barrier. Residence time distribution (RTD) functions were calculated from tracer data using two techniques: method of moments and a novel Gauss modelling approach. RTD functions were used to quantify hydraulic parameters: active wetland volume (e-value), water dispersion (N-value) and hydraulic efficiency (λ-value).For wetlands without barrier, significantly lower tracer mass recoveries were found from EVWs compared to FDWs and SVWs, signifying a risk of tracer methodological problems in small densely vegetated wetlands. These problems were minimized in wetlands with an inflow construction promoting distribution of incoming tracer solution.Compared to the method of moments, Gauss modelling seemed to produce more reliable λ-values but less reliable N-values. Data for precise hydraulic quantification were lost by Gauss modelling, as indicated by overall lower variance in these data sets and lower mass recoveries. However, Gauss modelling may minimize uncertainties associated with lithium immobilization/mobilization. Parameters were significantly affected by the RTD data analysis method, showing that the choice of method could affect evaluation of wetland hydraulics.The experimental wetlands in this study exhibited relatively high e-values and low N-values. This was probably caused by the small size of the wetlands and low water flow velocities, emphasizing that hydraulic parameter values obtained in small experimental wetlands may not be applicable to hydraulics in larger wetlands.The method of moments revealed lower e-values from EVWs compared to SVWs and FDWs. It was indicated that lower e-values were mainly caused by vegetation volumes. This highlighted a need for regular maintenance to secure efficient treatment volume in wetlands with dense vegetation.
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| 6. |
- Choudhury, Maidul I., et al.
(author)
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Enhancing nitrogen removal through macrophyte harvest and installation of woodchips-based floating beds in surface-flow constructed wetlands
- 2024
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In: Chemosphere. - Oxford : Elsevier. - 0045-6535 .- 1879-1298. ; 359
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Journal article (peer-reviewed)abstract
- Wetland management maintains nitrogen (N) removal capacity in mature and overgrown constructed wetlands (CWs). We evaluated whether CW management by macrophyte harvesting, and subsequent installation of woodchips-based floating beds (WFBs) planted with Glyceria maxima and Filipendula ulmaria improved N removal. In sixteen heavily overgrown experimental CWs, we applied four treatments: i) only macrophyte harvesting, ii) 5% of the harvested-CW surface covered with WFBs, iii) 20% WFBs cover, and iv) a control treatment (heavily overgrown). N removal was determined in all wetlands at nine occasions. Plant biomass accrual, N assimilation, and denitrification genes nirS, nirK, nosZI and nosZII on plant roots and woodchips from WFBs were estimated. Macrophyte harvesting improved N removal of heavily overgrown CWs, whereas subsequent WFB installation only sometimes improved N removal. Mean N removal efficiencies (± standard deviation) overall were 41 ± 15 %, 45 ± 20 %, 46 ± 16 % and 27 ± 8.3 % for treatments i to iv, respectively. Relative biomass production, root length and root surface area for G. maxima (mean ± standard deviation: 234 ± 114 %, 40 ± 6.5 cm, 6308 ± 1059 cm2g-1, respectively) were higher than those for F. ulmaria (63 ± 86 %, 28 ± 12 cm, 3131 ± 535 cm2g-1, respectively) whereas biomass N assimilation was higher for F. ulmaria (1.8 ± 0.9 gNm−2 of WFB) than for G. maxima (1.3 ± 0.5 gNm−2 of WFB). Denitrification gene abundance was higher on plant roots than on woodchips while G. maxima hosted higher root denitrification gene abundance than F. ulmaria. We conclude that macrophyte harvesting improves N removal in heavily overgrown CWs. WFBs installation has the potential to support plant growth and denitrification in surface-flow constructed wetlands. Further studies need to evaluate the long-term effects of macrophyte harvesting and WFB installation on N removal in CWs. © 2024 The Authors
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| 7. |
- Choudhury, Maidul I., et al.
(author)
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Enhancing wetland nitrogen removal through macrophyte harvest and installation of woodchips-based floating beds
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Other publication (other academic/artistic)abstract
- Constructed wetlands (CWs) remove nitrogen (N) more efficiently as wetlands age and vegetation establishes. However, when CWs become heavily overgrown and filled with plant litter and root mats, channels form and N removal declines. Here, management may maintain high N removal. We tested two CW management options 1) restoration through macrophyte harvesting including root mat removal, and 2) subsequent installation of woodchips-based floating beds (WFBs) to compensate macrophyte loss. In a field experiment, using 16 heavily overgrown experimental CWs, we applied four treatments: i) macrophyte harvesting, ii) macrophyte harvesting and 5% of the wetland surface covered with WFBs, iii) macrophyte harvesting and 20% WFB cover, and iv) a control treatment (heavily overgrown). WFBs were planted with Glyceria maxima and Filipendula ulmaria before installation. N removal efficiency, removal rate and removal rate coefficient ka were estimated on nine occasions. After the experiment, WFBs were removed and plant biomass accrual, N assimilation, and denitrification gene (nirS, nirK, nosZI and nosZII) abundance on plant roots and woodchips were studied.Macrophyte harvesting significantly improved N removal of heavily overgrown CWs, whereas WFBs installation only improved N removal in harvested treatments on some occasions. Both G. maxima and F. ulmaria grew well on WFBs. Relative biomass production, root length and root surface area were higher for G. maxima than for F. ulmaria whereas biomass N assimilation was higher for F. ulmaria. Denitrification gene abundance was higher on plant roots than on woodchips while G. maxima hosted higher root denitrification gene abundance than F. ulmaria. We conclude that macrophyte harvesting improves N removal in heavily overgrown CWs. Further long-term field studies are needed to precisely evaluate the contribution of WFBs to N removal in CWs.
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| 10. |
- Eller, Franziska, et al.
(author)
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Biomethane yield from different European Phragmites australis genotypes, compared with other herbaceous wetland species grown at different fertilization regimes
- 2020
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In: Resources. - Basel : MDPI. - 2079-9276. ; 9:5
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Journal article (peer-reviewed)abstract
- Phragmites australis, Typha latifolia, T. angustifolia and Arundo donax are tall wetland graminoids with the potential to replace fossil fuels under sustainable cultivation conditions. We investigated the biomethane (CH4) production of these four species, including four different genotypes of P. australis, which represent the high intraspecific diversity of European reed. All plants were grown under three different macronutrient supplies (no nutrients added, an equivalent of 75 kg N ha−1 year−1 added and an equivalent of 500 kg N ha−1 year−1 added). Biomethane production was measured in four independent batch digestion tests. Across all experiments, fertilization regime had little effect on CH4 yield, which was on average 222 ± 31 L kg−1 volatile solids (VS). The lowest yield was produced by T. angustifolia (140 L kgVS−1) receiving no nutrients, while the highest yield was produced by A. donax (305 L kgVS−1) in the highest nutrient treatment. The intraspecific diversity of P. australis did not affect biomethane production. All P. australis genotypes produced on average 226 ± 19 L CH4 kgVS−1, which, although high, was still lower than conventional biogas species. The biomass production of P. australis was less increased by fertilization than that of Typha sp. and A. donax, but all species had similar biomass without fertilization.
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