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Publications (10 of 65) Show all publications
Rullander, G., Lorenz, C., Herbert, R., Strömvall, A.-M., Vollertsen, J. & Dalahmeh, S. S. (2023). How effective is the retention of microplastics in horizontal flow sand filters treating stormwater?. Journal of Environmental Management, 344, Article ID 118690.
Open this publication in new window or tab >>How effective is the retention of microplastics in horizontal flow sand filters treating stormwater?
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2023 (English)In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 344, article id 118690Article in journal (Refereed) Published
Abstract [en]

Microplastics accumulate in stormwater and can ultimately enter freshwater recipients, and pose a serious risk to aquatic life. This study investigated the effectiveness of lab-scale horizontal flow sand filters of differing lengths (25, 50 and 100 cm) in retaining four types of thermoplastic microplastics commonly occurring in stormwater runoff (polyamide, polyethylene, polypropylene, and polyethylene terephthalate). Despite the differences in particle shape, size and density, the study revealed that more than 98% of the spiked microplastics were retained in all filters, with a slightly increased removal with increased filter length. At a flow rate of 1 mL/min and after one week of operation, 62–84% of the added microplastics agglomerated in the first 2 cm of the filters. The agglomerated microplastics included 96% of high-density fibers. Larger-sized particles were retained in the sand media, while microplastics smaller than 50 μm were more often detected in the effluent. Microplastics were quantified and identified using imaging based micro Fourier Transform Infrared Spectroscopy. The efficient retention of microplastics in low-flow horizontal sand filters, demonstrated by the results, highlights their potential importance for stormwater management. This retention is facilitated by various factors, including microplastic agglomeration, particle sedimentation of heavy fibers and favorable particle-to-media size ratios.

Place, publisher, year, edition, pages
Elsevier, 2023
National Category
Environmental Engineering
Identifiers
urn:nbn:se:uu:diva-516585 (URN)10.1016/j.jenvman.2023.118690 (DOI)001144203900001 ()
Funder
Swedish Research Council Formas
Available from: 2023-11-24 Created: 2023-11-24 Last updated: 2024-02-15Bibliographically approved
Wang, J., Carrera, J., Valhondo, C., Saaltink, M. W., Guerrero, J. P., Zhang, F. & Herbert, R. B. (2023). Multirate mass transfer simulation of denitrification in a woodchip bioreactor. Journal of Hydrology, 624, Article ID 129863.
Open this publication in new window or tab >>Multirate mass transfer simulation of denitrification in a woodchip bioreactor
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2023 (English)In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 624, article id 129863Article in journal (Refereed) Published
Abstract [en]

Denitrifying woodchip bioreactors (DWBs) have proven to be an efficient nature-based solution for nitrate removal. Modeling DWBs is required for improving their design and operation, but is hindered by the complexity of the modeled system where numerous chemical species and model parameters are needed. Reactions inside the woodchips are different from those at the edges, causing chemical localization (i.e., apparent simultaneous occurrence of incompatible reactions). We used the Multi Rate Mass Transfer (MRMT) approach to overcome these problems when simulating reactive transport processes in a DWB located at Kiruna, Sweden. Besides denitrification, other nitrogen-cycling processes (e.g., nitrification, dissimilatory nitrate reduction to ammonium, anammox) and alternative electron donors (e.g. oxygen, sulfate) were also considered. Biomass concentration is incorporated into the biochemical reaction rates, including growth and decay, to characterize microbial catalysis. We found that the MRMT model: 1) can account for the heterogeneity of the porous woodchips; 2) was capable of reproducing the nitrogen species evolution in the DWB with kinetic parameters from the literature; and 3) allows reproducing localized biochemical reactions (e.g., aerobic reactions on the woodchip edges, near the DWB entrance and anaerobic reactions inside); and 4) reproduces the full denitrification reactions sequence, but with the different reactions occurring in different portions of the woodchip (e.g., nitrate to nitrite near the edges and nitrite to nitrous oxide further inside). The latter observation suggests that increasing woodchip size may reduce the outflow of these undesired species.

Place, publisher, year, edition, pages
Elsevier, 2023
National Category
Environmental Sciences Water Engineering
Identifiers
urn:nbn:se:uu:diva-509034 (URN)10.1016/j.jhydrol.2023.129863 (DOI)001031861000001 ()
Projects
NITREM
Available from: 2023-08-14 Created: 2023-08-14 Last updated: 2023-08-15Bibliographically approved
Parvage, M. M. & Herbert, R. (2023). Sequential removal of nitrate and sulfate in woodchip and hematite: coated biochar bioreactor. Environmental Science: Water Research & Technology, 9(2), 489-499
Open this publication in new window or tab >>Sequential removal of nitrate and sulfate in woodchip and hematite: coated biochar bioreactor
2023 (English)In: Environmental Science: Water Research & Technology, ISSN 2053-1400, E-ISSN 2053-1419, Vol. 9, no 2, p. 489-499Article in journal (Refereed) Published
Abstract [en]

Laboratory column experiments have been used to study the sequential removal of nitrate (NO3) and sulfate (SO42−) from mine water, where NO3 was removed through denitrification and SO42− was removed through SO42− reduction and the subsequent precipitation of hydrogen sulfide (H2S) in a hematite-coated biochar (HCB) bioreactor. Denitrification and SO42− reduction were investigated in columns filled with pine woodchips and pine woodchips + biochar, both with and without the addition of lactate. Experimental results indicated that a >90% NO3 removal from 50 mg L−1 NO3-N was achieved at a hydraulic residence time of 5 days without lactate addition, but that SO42− reduction was minimal after an initial startup period. Lactate was added to stimulate SO42− reduction, producing H2S with >90% SO42− removal from an initial concentration of 361 mg L−1 SO42−-S. Sulfate concentrations were reduced to a greater extent in the woodchip + biochar column, and NH4+ production was enhanced in both columns after lactate addition. After treatment in the HCB columns, H2S and NH4+ were removed to >95%. X-ray photoelectron spectroscopy (XPS) indicated that S2−, S22−, S0 and NH4+ were accumulating in the HCB columns and surface-bound iron was converted from Fe(III) to Fe(II). The XPS results suggested that the reductive dissolution of hematite preceded the precipitation of H2S as FeS, pyrite and elemental sulfur on the HCB surfaces.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2023
National Category
Water Engineering Water Treatment
Identifiers
urn:nbn:se:uu:diva-491103 (URN)10.1039/d2ew00499b (DOI)000899139300001 ()
Available from: 2022-12-17 Created: 2022-12-17 Last updated: 2023-05-16Bibliographically approved
Herbert, R. B. & Nordström, A. (2021). Denitrifierande bioreaktorer: Rening av kväve i lakvatten. Vatten, 77, 173-183
Open this publication in new window or tab >>Denitrifierande bioreaktorer: Rening av kväve i lakvatten
2021 (Swedish)In: Vatten, ISSN 0042-2886, Vol. 77, p. 173-183Article in journal (Other academic) Published
Abstract [sv]

Sprängmedel baserade på ammoniumnitrat är idag de vanligaste sprängmedel som används inom industriella verksamheter såsom gruvdrift, bergtäkter och tunneldrivning för vägbygge. Studier från gruvindustrin har dock visat att en del av det sprängmedel som används (upp till 28 %) inte detonerar och med tiden läcker ut till närliggande recipienter, huvudsakligen som nitrat (NO3-). En denitrifierande bioreaktor är en passiv och kostnadseffektiv metod för att minska nitrathalter i lakvatten från sprängstensmassor och bergkrosshögar, och har sedan 2015 byggts och utvärderats på flera platser i Sverige. I sin enklaste form är bioreaktorn en grop som fylls med ett reaktivt material rikt på organiskt kol, vanligtvis träflis. Vatten med höga halter av NO3- tillåts flöda horisontellt genom det reaktiva materialet, där inkommande NO3- omvandlas till N2 genom den mikrobiella processen denitrifikation. Denna artikel sammanfattar bioreaktorstekniken och diskuterar dess användning för att minska nitrathalter i lakvatten från sprängstensmassor och bergkrosshögar, med fokus på design och drift för optimal processeffektivitet. En fallstudie från en bergtäkt i Kalmar län redovisas, där en bioreaktor har varit i drift i fyra år med en genomsnittlig nitratrening på 90 %. 

Abstract [en]

Ammonium nitrate-based explosives are the most commonly used explosives in various industries today,  including mining, rock quarrying, and tunnel excavation for roads. Studies from the mining industry have, however, shown that up to 28% of the explosives remain undetonated. These undetonated explosives dissolve in water and eventually discharge to nearby surface water and groundwater recipients, primarily in the form of nitrate (NO3-). A denitrifying bioreactor is a passive and cost-effective technique for reducing NO3-concentrations in leachate from piles of excavated rock, and have been built and evaluated  at several sites in Sweden since 2015. A bioreactor is a simple construction and consists of an excavation  that is filled with a reactive organic material, such as woodchips. Water with high concentrations of NO3- flows horizontally through the reactive material and the inflowing NO3- is transformed to N2 by the process of microbial denitrification. This paper provides a summary of the denitrifying bioreactor technique  as a potential method for reducing nitrate concentrations in leachate from rock piles, with focus on design  and operation criteria for optimal performance. A case study from a rock quarry in Kalmar County is presented, where the bioreactor has been in operation for four years with an average nitrate removal of 90 %.

Keywords
Denitrification, remediation, nitrate, ammonium, quarrying, mining
National Category
Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-456842 (URN)
Available from: 2021-10-22 Created: 2021-10-22 Last updated: 2021-10-26Bibliographically approved
Nordström, A., Hellman, M., Hallin, S. & Herbert, R. B. (2021). Microbial controls on net production of nitrous oxide in a denitrifying woodchip bioreactor. Journal of Environmental Quality, 50(1), 228-240
Open this publication in new window or tab >>Microbial controls on net production of nitrous oxide in a denitrifying woodchip bioreactor
2021 (English)In: Journal of Environmental Quality, ISSN 0047-2425, E-ISSN 1537-2537, Vol. 50, no 1, p. 228-240Article in journal (Refereed) Published
Abstract [en]

Denitrifying woodchip bioreactors (DWBs) are potential low‐cost technologies for the removal of nitrate (NO3) in water through denitrification. However, if environmental conditions do not support microbial communities performing complete denitrification, other N transformation processes will occur resulting in the export of nitrite (NO2), nitrous oxide (N2O), or ammonium (NH4+). In order to identify the factors controlling the relative accumulation of NO2, N2O, and/or NH4+ in DWBs, porewater samples were collected over two operational years from a DWB designed for removing NO3 from mine water. Woodchip samples were collected at the end of the operational period. Changes in the abundances of functional genes involved in denitrification, N2O reduction, and dissimilatory nitrate reduction to ammonium were correlated with pore water chemistry and temperature. Temporal changes in the abundance of the denitrification gene nirS were significantly correlated with increases in porewater N2O concentrations, and indicated the preferential selection of incomplete denitrifying pathways ending with N2O. Temperature and the TOC/NO3 ratio were strongly correlated with NH4+ concentrations and inversely correlated with the ratio between denitrification genes and the genes indicative of ammonification (∑nir/nrfA), suggesting an environmental control on NO3 transformations. Overall, our results for a DWB operated at hydraulic residence times of 1.0 ‐ 2.6 days demonstrate the temporal development in the microbial community and indicate an increased potential for N2O emissions with time from the DWB.

National Category
Water Engineering
Research subject
Hydrology
Identifiers
urn:nbn:se:uu:diva-429749 (URN)10.1002/jeq2.20181 (DOI)000617480400019 ()33270921 (PubMedID)
Funder
Vinnova, 2014-011334
Available from: 2021-02-05 Created: 2021-02-05 Last updated: 2021-03-23Bibliographically approved
Nordström, A. & Herbert, R. (2019). Identification of the temporal control on nitrate removal rate variability in a denitrifying woodchip bioreactor. Ecological Engineering: The Journal of Ecotechnology, 127, 88-95
Open this publication in new window or tab >>Identification of the temporal control on nitrate removal rate variability in a denitrifying woodchip bioreactor
2019 (English)In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 127, p. 88-95Article in journal (Refereed) Published
Abstract [en]

Nitrate (NO3) removal rates in a denitrifying woodchip bioreactor (DWB) removing NO3 from mine water in a subarctic climate was modeled with the purpose of determining the processes controlling variability in NO3 removal rates over time. The Eyring equation was used to define the temperature dependency, while a rate law was used to describe the NO3 concentration dependency of the NO3 removal rates. The results show that the temperature and NO3 concentration dependency of the NO3 removal rates changes over time in the DWB due to the preferential selection of conceptualized NO3 - reducing bacteria favoring low temperatures, with the mean temperature optimum of the NO3 reducing consortium decreasing from 24.2 °C to 16.0 °C following the first year of DWB operations. It is suggested that the selection of the low temperature NO3 reducers in the DWB represented an increased dependence on cross-feeding between a fermentative community, producing the reactive organic carbon substrate, and a denitrifying community, consuming the organic carbon substrate, with the temporal variability in NO3 removal rates being controlled by the stabilization of the microbial community structure. It is also suggested that the life expectancy of DWBs is more related to the stability of the cross-feeding between the fermenting microbial community and the denitrifying microbial community, than to the total carbon content.

Keywords
Woodchip bioreactor, Modeling, Macromolecular rate theory, Selection, Temperature, Longevity
National Category
Water Treatment
Identifiers
urn:nbn:se:uu:diva-366588 (URN)10.1016/j.ecoleng.2018.11.015 (DOI)000455632500009 ()
Funder
VINNOVA, 2014-01134
Available from: 2018-11-21 Created: 2018-11-21 Last updated: 2019-03-27Bibliographically approved
Nordström, A. & Herbert, R. (2018). Determination of major biogeochemical processes in a denitrifying woodchip bioreactor for treating mine drainage. Ecological Engineering: The Journal of Ecotechnology, 110, 54-66
Open this publication in new window or tab >>Determination of major biogeochemical processes in a denitrifying woodchip bioreactor for treating mine drainage
2018 (English)In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 110, p. 54-66Article in journal (Refereed) Published
Abstract [en]

At the Kiruna iron ore mine in northern Sweden, mine drainage and process water contain elevated concentrationsof nitrate (NO3−) from the use of ammonium nitrate fuel oil explosives. In order to investigate thetreatment capacity of a denitrifying woodchip bioreactor technique for the removal of NO3− through denitrification,a bioreactor was installed at the mine site in 2015 and operated for two consecutive years. Neutral-pHmine drainage and process water containing 22 mg NO3−-N and 1132 mg SO42− (average) was passed throughthe bioreactor which was filled with a reactive mixture of pine woodchips and sewage sludge, at treatmenttemperatures ranging between 0.8 and 17 °C. At bioreactor temperatures above ∼5 °C, NO3− removal proceededto below detection limits (0.06 mg N L−1) without substantial production of nitrite (NO2−), ammonium(NH4+), nitrous oxide (N2O), or methane (CH4). The relative production of NH4+ and N2O to the NO3− reducedincreased as bioreactor temperatures decreased below ∼5 °C. Based on the resultant changes in alkalinity andpH from the production of bicarbonate (HCO3−) and carbonic acid (H2CO3), a stoichiometric mass balancemodel indicated that denitrification, nitrate reduction to ammonium (DNRA), sulfate reduction, and fermentationwere the major biogeochemical processes controlling pH, alkalinity and nitrogen, sulfur and carbonconcentrations in the system. It is suggested that fermentation changed from being mainly butyrate producing toacetate producing with time, triggering a decline in biogeochemical process diversity and leaving denitrificationas the sole major electron accepting process.

Keywords
Denitrification, sulfate reduction, DNRA, woodchip bioreactor, temperature, biogeochemical processes, mine drainage, nitrogen, denitrifikation, sulfatreduktion, DNRA, bioreaktor med träflis, temperatur, biogeokemiska processes, gruvvatten, kväve
National Category
Geochemistry
Research subject
Hydrology
Identifiers
urn:nbn:se:uu:diva-331698 (URN)10.1016/j.ecoleng.2017.09.018 (DOI)000417048500007 ()
Projects
miNing
Funder
VINNOVA, 2014-01134
Available from: 2017-10-17 Created: 2017-10-17 Last updated: 2019-03-27Bibliographically approved
Nordström, A. & Herbert, R. (2017). Denitrification in a low-temperature bioreactorsystem at two different hydraulic residence times: laboratory column studies. Environmental technology, 38(11), 1362-1375
Open this publication in new window or tab >>Denitrification in a low-temperature bioreactorsystem at two different hydraulic residence times: laboratory column studies
2017 (English)In: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 38, no 11, p. 1362-1375Article in journal (Refereed) Published
Abstract [en]

Nitrate removal rates in a mixture of pine woodchips and sewage sludge were determined in laboratory column studies at 5°C, 12°C, and 22°C, and at two different hydraulic residence times (HRTs; 58.2–64.0 hours and 18.7–20.6 hours). Baffles installed in the flow path were tested as a measure to reduce preferential flow behavior, and to increase the nitrate removal in the columns. The nitrate removal in the columns was simulated at 5°C and 12°C using a combined Arrhenius-Monod equation controlling the removal rate, and a first-order exchange model for incorporation of stagnant zones. Denitrification in the mixture of pine woodchips and sewage sludge reduced nitrate concentrations of 30 mg N L−1 at 5°C to below detection limits at a HRT of 58.2–64.0 hours. At a HRT of 18.7–20.6 hours, nitrate removal was incomplete. The Arrhenius frequency factor and activation energy retrieved from the low HRT data supported abiochemically controlled reaction rate; the same parameters, however, could not be used to simulate the nitrate removal at high HRT. The results show an inversely proportional relationship between the advection velocity and the nitrate removal rate, suggesting that bioreactor performance could be enhanced by promoting low advection velocities.

National Category
Oceanography, Hydrology and Water Resources
Research subject
Hydrology
Identifiers
urn:nbn:se:uu:diva-303686 (URN)10.1080/09593330.2016.1228699 (DOI)000400464400004 ()27603564 (PubMedID)
Projects
MiNing
Funder
VINNOVA, P31054-1
Available from: 2016-09-22 Created: 2016-09-22 Last updated: 2019-03-27Bibliographically approved
Das, P., Sarma, K., Kumar Jha, P., Ranjan, R., Herbert, R. & Kumar, M. (2016). Understanding the Cyclicity of Chemical Weatheringand Associated CO2Consumption in the BrahmaputraRiver Basin (India): The Role of Major Rivers in ClimateChange Mitigation Perspective. Aquatic geochemistry, 22(3), 225-251
Open this publication in new window or tab >>Understanding the Cyclicity of Chemical Weatheringand Associated CO2Consumption in the BrahmaputraRiver Basin (India): The Role of Major Rivers in ClimateChange Mitigation Perspective
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2016 (English)In: Aquatic geochemistry, ISSN 1380-6165, E-ISSN 1573-1421, Vol. 22, no 3, p. 225-251Article in journal (Refereed) Published
Abstract [en]

Weathering of rocks that regulate the water chemistry of the river has been used to evaluate the CO2 consumption rate which exerts a strong influence on the global climate. The foremost objective of the present research is to estimate the chemical weathering rate (CWR) of the continental water in the entire stretch of Brahmaputra River from upstream to downstream and their associated CO2 consumption rate. To establish the link between the rapid chemical weathering and thereby enhance CO2 drawdown from the atmosphere, the major ion composition of the Brahmaputra River that drains the Himalaya has been obtained. Major ion chemistry of the Brahmaputra River was resolved on samples collected from nine locations in pre-monsoon, monsoon and post-monsoon seasons for two cycles: cycle I (2011-2012) and cycle II (2013-2014). The physico-chemical parameters of water samples were analysed by employing standard methods. The Brahmaputra River was characterized by alkalinity, high concentration of Ca2+ and HCO3 (-) along with significant temporal variation in major ion composition. In general, it was found that water chemistry of the river was mainly controlled by rock weathering with minor contributions from atmospheric and anthropogenic sources. The effective CO2 pressure (log) for pre-monsoon, monsoon and post-monsoon has been estimated. The question of rates of chemical weathering (carbonate and silicate) was addressed by using TDS and run-off (mm year(-1)). It has been found that the extent of CWR is directly dependent on the CO2 consumption rate which may be further evaluated from the perspective of climate change mitigation The average annual CO2 consumption rate of the Brahmaputra River due to silicate and carbonate weathering was found to be 0.52 (x10(6) mol Km(-2) year(-1)) and 0.55 (x10(6) mol Km(-2) year(-1)) for cycle I and 0.49 (x10(6) mol Km(-2) year(-1)) and 0.52 (x10(6) mol Km(-2) year(-1)) for cycle II, respectively, which were significantly higher than that of other Himalayan rivers. Estimation of CWR of the Brahmaputra River indicates that carbonate weathering largely dominates the water chemistry of the Brahmaputra River.

National Category
Geochemistry
Identifiers
urn:nbn:se:uu:diva-289174 (URN)10.1007/s10498-016-9290-6 (DOI)000376579000004 ()
External cooperation:
Available from: 2016-04-29 Created: 2016-04-29 Last updated: 2017-11-30Bibliographically approved
Kumar, M., Herbert, R., Kumar Jha, P., Prakash Deka, J., Rao, M., Ramanathan, A. & Kumar, B. (2016). Understanding the Seasonal Dynamics of the Groundwater Hydrogeochemistry in National Capital Territory (NCT) of India Through Geochemical Modelling. Aquatic geochemistry, 22(3), 211-224
Open this publication in new window or tab >>Understanding the Seasonal Dynamics of the Groundwater Hydrogeochemistry in National Capital Territory (NCT) of India Through Geochemical Modelling
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2016 (English)In: Aquatic geochemistry, ISSN 1380-6165, E-ISSN 1573-1421, Vol. 22, no 3, p. 211-224Article in journal (Refereed) Published
Abstract [en]

A geochemical assessment of seasonal dynamics in the groundwater chemistry of the National Capital Territory (NCT), Delhi, was attempted through geochemical modelling, mineral precipitation sequences with rainfall and water evaporation cycle. Saturation indices calculated using PHREEQC indicated that the degree of water-rock equilibrium changes significantly from pre-monsoon to post-monsoon. The schematic model of SI change with water table fluctuation showed that during monsoon, as rainwater percolates through the soil, partial pressure of CO2 becomes higher than that of the atmospheric value and led to the formation of more carbonic acid that react with the carbonate minerals to produce , Mg2+ and Ca2+. The thermodynamic stability relationships of water chemistry in the Na, K, Ca and Mg silicate systems showed that for the samples with higher EC equilibrium between clay and primary minerals is not likely to be the main processes controlling variation in the groundwater chemistry. Chloro-alkaline indices (CAI) are positive when the groundwater level is high and become negative with the lowering of water level, i.e. when water level is high, reverse ion exchange is dominant. In case of pre-monsoon season, lower and negative value of CAI-1 and CAI-2 indicates dominance of ion exchange process and increases dissolved solid concentration in groundwater. The conceptual geochemical model depicted that water table fluctuation resulting from heavy pumping/withdrawal and recharge in association with the variation in DO, and Fe regulates the water-mineral equilibrium. The conceptual geochemical model explained the hydrogeochemical processes and their variations with water table fluctuation and, thus, highlighted the descriptive capabilities of PHREEQC. The study suggested that in the subsurface environment, complex interactions are simultaneously functioning, and hence, significant seasonal variations are likely to be very influential due to monsoonal recharge and subsequent changes in the saturation states of the water.

National Category
Geochemistry
Identifiers
urn:nbn:se:uu:diva-289180 (URN)10.1007/s10498-016-9289-z (DOI)000376579000003 ()
External cooperation:
Available from: 2016-04-29 Created: 2016-04-29 Last updated: 2017-11-30Bibliographically approved
Projects
Sulfate removal from mine leachate - development of full-scale bioreactor system (SULFREM) [2021-04669_VINNOVA]; Uppsala University
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-7561-757x

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