| 1. |
- Knutsson, Pavleta, 1980, et al.
(författare)
-
Phycoremediation of heavy metals
- 2016
-
Ingår i: Energy and Clean Technologies Conference Proceedings, Sgem 2016, Vol I. - 9786197105636 ; , s. 533-540
-
Konferensbidrag (refereegranskat)abstract
- Increasing amounts of heavy metals is a growing societal problem. By using ion exchangers, heavy metals can be captured and thereby their environmental impact can be decreased. Microalgae have been shown to adsorb metals; the algal cell wall contains functional groups, such as amino-, carboxyl-, hydroxyl- and sulphate groups, to which the various metal ions could bind [1]. This makes them suitable as a sustainable alternative for environmental remediation. Removal of pollutants with algae is called phycoremediation and is well studied for e.g. waste water [2]. Within this project, we study the potential of microalgae for remediating heavy metals in low concentration originating from leaching of combustion ashes, by measuring the metal binding capacity by three phytoplankton species: Chlorella sauna, Dunaliella sauna and Scendesmus obliquus. The heavy metals assessed are divalent ions of copper (Cu), cadmium (Cd), zinc (Zn), mercury (Hg) and lead (Pb). The effect of pH has been determined, as well as binding over time.
|
|
| 2. |
- Arpadjan, S., et al.
(författare)
-
Field sampling, speciation and determination of dissolved iron (II) and iron (III) in waters
- 2012
-
Ingår i: Bulgarian Chemical Communications. - 0861-9808. ; 44:4, s. 299-306
-
Tidskriftsartikel (refereegranskat)abstract
- A simple and rapid field sampling procedure was developed for the speciation of dissolved Fe(II) and Fe(III) in waters. The determination of iron species was possible by selective batch solid phase extraction of Fe(III) using chelating resin Chelex-100 in H+ form, sample acidity range of pH 1.5-2.5, elution with 0.03 mol L-1 NH4-EDTA, and detection of Fe(III) by flame or electrothermal atomic absorption spectrometry (ETAAS). The concentration of Fe(II) was determined in the solution above the resin by direct ETAAS or after adsorption on Chelex-100 in NH4+ form without the need for preoxidation of Fe(II) to Fe(III). Water samples were collected in situ and filtered by passing them through a syringe filter (0.45 mu m). The batch procedure was performed at the field and then, the tubes containing the resins with the loaded analytes were returned to the laboratory where the iron species were eluted and determined. Field sampling prevents changes in the oxidation state of iron. The effect of humic acid was also investigated. The results obtained indicated that the method was not affected by the presence of up to 0.01% humic acid. The limit of detection (3s) was 0.8 mu g L-1 Fe (ETAAS detection). The relative standard deviation (n=10) ranged from 2% at the 1 mg L-1 Fe up to 20% at the 1 mu g L-1 Fe(III) level. Recoveries of spiked Fe(II) and Fe(III) in river, lake, tap and groundwater samples ranged from 93 to 105%.
|
|
| 3. |
- Arpadjan, S., et al.
(författare)
-
Speciation analysis of thallium in water samples after separation/ preconcentration with the EmporeTM chelating disk
- 2011
-
Ingår i: International Journal of Environmental Analytical Chemistry. - : Informa UK Limited. - 0306-7319 .- 1029-0397. ; 91:11, s. 1088-1099
-
Tidskriftsartikel (refereegranskat)abstract
- A simple, reliable and novel solid phase extraction procedure using the Empore chelating disk has been developed for determination of Tl(I) and Tl(III) in environmental water samples by electrothermal atomic absorption spectrometry (ETAAS). The influence of humic acids on separation/preconcentration of thallium species with the Empore chelating disk is investigated. The preconcentration factor and detection limit are 500 and 5 ng L-1, respectively. The recoveries are in the range 93-103% for mineral, pond, sea, snowmelt, waste waters at 28-500 ng L-1 Tl and in the range 82-112% for river waters at 18-28 ng L-1 Tl.
|
|
| 4. |
- Knutsson, Jesper, 1973, et al.
(författare)
-
Evaluation of a passive sampler for the speciation of metals in urban runoff water
- 2013
-
Ingår i: Environmental Sciences: Processes and Impacts. - : Royal Society of Chemistry (RSC). - 2050-7895 .- 2050-7887. ; 15:12, s. 2233-2239
-
Tidskriftsartikel (refereegranskat)abstract
- Metals in urban runoff water need to be monitored in order to estimate fluxes and assess their impact on the aquatic environment. Passive sampling is a useful and reliable emerging tool for measuring time averaged concentrations of metals in water bodies. This paper describes the deployment of a passive sampler to measure Cu, Ni and Zn in an urban runoff water treatment facility. The concentrations derived from the passive samplers are compared to concentrations obtained from an automated water sampler which provides pooled spot water samples and to model predictions from the visualMINTEQ computer speciation code. Results show that visualMINTEQ predictions partly describe the metal speciation in non-equilibrium systems. In addition we conclude that passive samplers are useful for monitoring and characterization of metal speciation under chemodynamic conditions. © 2013 The Royal Society of Chemistry.
|
|
| 5. |
- Knutsson, Jesper, 1973, et al.
(författare)
-
Water and energy savings from greywater reuse: a modelling scheme using disaggregated consumption data
- 2021
-
Ingår i: International Journal of Water Resources Development. - : Springer Science and Business Media LLC. - 1360-0648 .- 0790-0627 .- 2538-3604 .- 2522-0101. ; 5:1, s. 13-24
-
Tidskriftsartikel (refereegranskat)abstract
- Municipal drinking water supplies are under great stress globally, and one way to mitigate the problems is the reutilization of wastewater in various settings. In this paper, a greywater reuse scheme and the impact of system design and configuration on water and energy savings are investigated. The objective of the paper was to investigate the impact of hydraulic design and performance of a greywater treatment and reuse system on water and energy savings. A simulation model was created based on real, disaggregated water consumption data that predicts the reuse potential. Three scenarios were investigated; (1) greywater collection from the bathroom and reuse for toilet flushing, (2) greywater collection from bathroom sinks and showers, and reuse as hot water for sinks and showers, and (3) a combination of (1) and (2) where greywater collection from bathroom sinks and showers is used for toilet flushing, sinks and shower. The results indicate hot water reductions between 55.6 and 58.2%, while cold water reductions ranged from 5.8 to 30.6%. Reductions in energy for producing hot water between 43.5 and 46.8% were observed. Recommendations per connected user for hydraulic design ranged from 0.033 to 0.1 dm3 min−1, 3 dm3, and 0.7–10 dm3 for treatment capacity, collection and holding tank volume.
|
|
| 6. |
- Knutsson, Pavleta, 1980, et al.
(författare)
-
Characterization of ash component desorption on novel bed material for fluidized bed boilers
- 2018
-
Ingår i: International Multidisciplinary Scientific GeoConference Surveying Geology and Mining Ecology Management, SGEM. - 1314-2704. ; 18:4.1, s. 195-202
-
Konferensbidrag (refereegranskat)abstract
- The use of biomass as a renewable fuel for production of heat and electricity is regarded as a key to reduce fossil fuel dependency, and thereby to reduce net CO2 emissions. Fluidized bed (FB) technology is widely accepted as the most energy efficient process for thermal conversion of biomass. One of the often-mentioned drawbacks is the building up of agglomerates within the process because of bed material-ash interaction. To avoid unplanned operational stops due to agglomeration, bed material is continuously replenished and spent bed material is removed in the form of bottom ash. The spent bed material cannot readily be reused and is usually deposited or used as construction filler material. Sand is the primary choice for bed material but novel bed materials are being tested to improve biomass conversion. Even though agglomeration is reduced and the energy efficiency of the conversion process is improved, bottom and fly ash are still being generated and need to be managed. To conceive new management strategies there is need to improve the understanding of the composition and stability of the compounds formed from the interaction between biomass ash and the novel bed materials. In the present work four bed materials (Olivine, Ilmenite, Feldspar and Manganese ore), all minerals, have been used in a biomass fueled 10MW CFB boiler. The materials have been sampled upon similar gas composition and time exposures in order to assure similarity in bed material “activity”. Bed material characterization followed by stepwise leaching have been used to identify opportunities in terms of pretreatment prior to deposition or/and the possibilities for alternative reuse.
|
|
| 7. |
- Knutsson, Pavleta, 1980, et al.
(författare)
-
Potassium speciation and distribution for the K2CO3 additive-induced activation/deactivation of olivine during gasification of woody biomass
- 2019
-
Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 248, s. 538-544
-
Tidskriftsartikel (refereegranskat)abstract
- The GoBiGas plant, which comprises a 32-MW th dual fluidized bed gasifier, was constructed as a demonstration unit for converting biomass to biomethane via gasification. On several occasions during the commissioning of the plant, low activity of the olivine bed generated a high content of tar in the produced gas, which was deleterious to the downstream equipment. The problem was attributed to a deficiency of ash constituents, and the solution was to control activation of the bed material through the addition of K 2 CO 3 to the process. This enabled extended operational periods without tar-related issues. The achieved activity could be lost during interrupted operation at which time the activation procedure had to be repeated. In the present paper analysis of the bed material samples extracted upon activation and after loss of activity using Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM-EDS)showed similar morphologies for the ash layers formed around the olivine particles. The observed differences mainly related to the distributions of potassium (K)across the layers. Furthermore, surface analysis showed differences in K speciation within the outer regions. K solubility tests and X-ray photoelectron spectroscopy analyses indicated that K was present as an oxide/hydroxide rather than as a silicate on the surface of the active olivine. The presented results are of major relevance for the operation of dual fluidized bed gasifiers with fuels that are potassium-lean when ash components need to be supplied as additives.
|
|
| 8. |
- Knutsson, Pavleta, 1980, et al.
(författare)
-
Use of natural ores in thermal conversion of biomass
- 2018
-
Ingår i: International Multidisciplinary Scientific GeoConference Surveying Geology and Mining Ecology Management, SGEM. - 1314-2704. ; 18:4.1, s. 791-798
-
Konferensbidrag (refereegranskat)abstract
- To decrease the CO2 levels in the atmosphere without compromising with the electricity production and energy security two different issues have to be addressed – replacement of the current use of fossil fuels with CO2-neutral fuels and increase in the efficiency of the existing processes for thermal conversion. Fluidized bed (FB) thermal conversion is usually considered as the most energy efficient choice when biomass and municipal solid waste are used as fuels. The bed material that is used commonly within FB boilers is sand. With the demand to increase the efficiency of the electricity generation process, alternative bed materials have been tested. These materials are usually naturally occurring minerals containing transient oxides, most often Fe or Mn. The present paper presents three naturally occurring minerals that may be utilized as bed materials – olivine, ilmenite and manganese ore, while comparing with industrial silica sand for reference. The feasibility of their utilization as bed materials in thermal conversion of biomass on their further use is discussed.
|
|
| 9. |
- Allan, I. J., et al.
(författare)
-
Chemcatcher and DGT passive sampling devices for regulatory monitoring of trace metals in surface water
- 2008
-
Ingår i: Journal of Environmental Monitoring. ; 10:7, s. 821-829
-
Tidskriftsartikel (refereegranskat)abstract
- This work aimed to evaluate whether the performance of passive sampling devices in measuring time-weighted average (TWA) concentrations supports their application in regulatory monitoring of trace metals in surface waters, such as for the European Union's Water Framework Directive (WFD). The ability of the Chemcatcher?? and the diffusive gradient in thin film (DGT) device sampler to provide comparable TWA concentrations of Cd, Cu, Ni, Pb and Zn was tested through consecutive and overlapping deployments (7-28 days) in the River Meuse (The Netherlands). In order to evaluate the consistency of these TWA labile metal concentrations, these were assessed against total and filtered concentrations measured at relatively high frequencies by two teams using standard monitoring procedures, and metal species predicted by equilibrium speciation modeling using Visual MINTEQ. For Cd and Zn, the concentrations obtained with filtered water samples and the passive sampling devices were generally similar. The samplers consistently underestimated filtered concentrations of Cu and Ni, in agreement with their respective predicted speciation. For Pb, a small labile fraction was mainly responsible for low sampler accumulation and hence high measurement uncertainty. While only the high frequency of spot sampling procedures enabled the observation of higher Cd concentrations during the first 14 days, consecutive DGT deployments were able to detect it and provide a reasonable estimate of ambient concentrations. The range of concentrations measured by spot and passive sampling, for exposures up to 28 days, demonstrated that both modes of monitoring were equally reliable. Passive sampling provides information that cannot be obtained by a realistic spot sampling frequency and this may impact on the ability to detect trends and assess monitoring data against environmental quality standards when concentrations fluctuate. ?? The Royal Society of Chemistry.
|
|
| 10. |
- Allan, Ian J., et al.
(författare)
-
Evaluation of the Chemcatcher and DGT passive samplers for monitoring metals with highly fluctuating water concentrations
- 2007
-
Ingår i: Journal of Environmental Monitoring. ; 9:7, s. 672-681
-
Tidskriftsartikel (refereegranskat)abstract
- Passive sampling devices accumulate chems. continuously from water and can provide time weighted av. (TWA) concns. of pollutants over the exposure period. Hence, they offer a no. of advantages over other conventional monitoring techniques such as spot or grab sampling. The diffusive gradient in thin film (DGT) and the Chemcatcher passive samplers can be used to provide TWA concns. of labile metals, but the approaches to their calibration differ. DGT uses diffusion coeffs. of metals in the hydrogel layer, whereas Chemcatcher uses metal specific uptake rates, with both sets of values obtained under controlled lab. conditions with const. aq. metal concns. However, little is known of how such samplers respond to fluctuating concns. We evaluated the responsiveness of these two passive sampling devices to rapidly changing concns. of Cd, Cu, Ni, Pb and Zn in natural freshwater, over a relatively short deployment time. Maximum metal concns. in water were varied between 70 and 140 mg L-1. Expts. were carried out in a tank with a rotating carousel system and filled with Meuse River water, allowing a degree of control over exptl. conditions while using natural river water. Fluctuating concns. were obtained by stepwise addn. of std. solns. of the metals. The reliability and accuracy of the TWA concns. measured by the samplers were assessed by comparison with concns. of the metals in spot samples of water taken regularly over the deployment period. The spot samples of water were either unfiltered (total), filtered (0.45 mm) or ultrafiltered (5 kDa). Predictive speciation modeling using the visual MINTEQ program was also undertaken. There was reasonable agreement between the TWA concns. of Cd and Ni obtained with Chemcatcher and DGT and the total Cd and Ni concns. measured in repeated unfiltered spot samples. For elements (i.e. Cu, Pb, Zn) that assoc. to a significant degree with suspended solids, colloids or dissolved org. carbon, or form complexes with large org. ligands, optimum agreement was with the filtered or ultrafiltered fractions and with the predicted inorg. and inorg.-fulvic acid assocd. fractions. While Chemcatcher-based TWA concn. ranges for Cu and Zn were in best agreement with the total filtered fraction, there was lack of agreement for Pb. The combined use of DGT devices with open pore (OP) and restricted pore (RP) gels allowed the labile fraction of metal assocd. with large org. ligands or DOC to be differentiated and quantified, since this is available to DGT OP but unable to diffuse into the DGT RP. This evaluation of the two sampling devices clearly demonstrated their ability to react reliably to transient peaks in concn. of metal pollutants in water and indicated where future efforts are needed to improve calibration data. Such samplers may prove valuable in responding to the monitoring requirements of the European Union's Water Framework Directive. [on SciFinder (R)]
|
|
