| 1. |
- Bojcevska, Hristina, 1977-, et al.
(författare)
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Impact of loads, season, and plant species on the performance of a tropical constructed wetland polishing effluent from sugar factory stabilization ponds
- 2007
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Ingår i: Ecological Engineering. - 0925-8574 .- 1872-6992. ; 29:1, s. 66-76
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Tidskriftsartikel (refereegranskat)abstract
- The effects of wastewater loading rates and two macrophyte species on treatment of sugar factory stabilization pond effluent were investigated in a pilot-scale free water surface constructed wetland (FWS CW) system in western Kenya. For 12 months, four CWs were operated at a hydraulic loading rate of 75 mm day−1 and four at 225 mm day−1. Half the CWs were planted with Cyperus papyrus and half with Echinochloa pyramidalis. Water samples were taken at the inlets and outlets and analyzed for TP, TDP, NH4-N, and TSS. Mass removal rates of the selected water quality parameters were compared during three periods designated the short rain (period 1), dry (period 2), and long rain (period 3) seasons. There was a significant linear relationship between the mass removal rate of TP, NH4-N, and TSS and the mass load, and season had a significant effect on the mass removal rate of TSS, NH4-N, and TDP. Mass loading rates for TDP were about 78% of those for TP, whereas TDP comprised 78–99% of TP mass outflow rates, indicating a release of dissolved P within the CWs. The only significant difference between the two macrophyte species was associated with mass removal of NH4-N, with more efficient removal in CWs planted with C. papyrus than those with E. pyramidalis. TP mass removal rates were 50–80% higher when a mean water loss for CWs 6–8 during periods 1 and 2 was assumed to represent evapotranspiration for all CWs in period 3 instead of pan evaporation data. This illustrated the importance of accurate estimations of evapotranspiration for pollutant mass removal rates in CWs in tropical climates.
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| 2. |
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| 3. |
- Andersson, J., et al.
(författare)
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Free water surface wetlands for wastewater treatment in Sweden : Nitrogen and phosphorus removal
- 2005
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Ingår i: Water Science and Technology. - 0273-1223 .- 1996-9732. ; 51:9, s. 39-46
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Tidskriftsartikel (refereegranskat)abstract
- In South Sweden, free water surface wetlands have been built to treat wastewater from municipal wastewater treatment plants. Commonly, nitrogen removal has been the prime aim, though a significant removal of tot-P and BOD7 has been observed. In this study, performance data for 3-8 years from four large (20-28 ha) FWS wetlands have been evaluated. Two of them receive effluent from WWTP with only mechanical and chemical treatment. At the other two, the wastewater has also been treated biologically resulting in lower concentrations of BOD7 and NH4+-N. The wetlands performed satisfactorily and removed 0.7-1.5 ton N ha-1 yr-1 as an average for the time period investigated, with loads between 1.7 and 6.3 ton N ha-1 yr-1. Treatment capacity depended on the pre-treatment of the water, as reflected in the k20-values for N removal (first order area based mode). In the wetlands with no biological pre-treatment, the k20-values were 0.61 and 1.1 m month-1, whereas for the other two they were 1.7 and 2.5 m month-1. P removal varied between 10 and 41 kg ha-1 yr-1, and was related to differences in loads, P speciation and to the internal cycling of P in the wetlands. © IWA Publishing 2005.
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| 4. |
- Bojcevska, Hristina, 1977-, et al.
(författare)
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Impact of loads, season, and plant species on the performance of a tropical constructed wetland polishing effluent from sugar factory stabilization ponds
- 2007
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Ingår i: Ecological Engineering. - : Elsevier BV. - 0925-8574 .- 1872-6992. ; 29:1, s. 66-76
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Tidskriftsartikel (refereegranskat)abstract
- The effects of wastewater loading rates and two macrophyte species on treatment of sugar factory stabilization pond effluent were investigated in a pilot-scale free water surface constructed wetland (FWS CW) system in western Kenya. For 12 months, four CWs were operated at a hydraulic loading rate of 75 mm day−1 and four at 225 mm day−1. Half the CWs were planted with Cyperus papyrus and half with Echinochloa pyramidalis. Water samples were taken at the inlets and outlets and analyzed for TP, TDP, NH4-N, and TSS. Mass removal rates of the selected water quality parameters were compared during three periods designated the short rain (period 1), dry (period 2), and long rain (period 3) seasons. There was a significant linear relationship between the mass removal rate of TP, NH4-N, and TSS and the mass load, and season had a significant effect on the mass removal rate of TSS, NH4-N, and TDP. Mass loading rates for TDP were about 78% of those for TP, whereas TDP comprised 78–99% of TP mass outflow rates, indicating a release of dissolved P within the CWs. The only significant difference between the two macrophyte species was associated with mass removal of NH4-N, with more efficient removal in CWs planted with C. papyrus than those with E. pyramidalis. TP mass removal rates were 50–80% higher when a mean water loss for CWs 6–8 during periods 1 and 2 was assumed to represent evapotranspiration for all CWs in period 3 instead of pan evaporation data. This illustrated the importance of accurate estimations of evapotranspiration for pollutant mass removal rates in CWs in tropical climates.
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| 5. |
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| 6. |
- Geranmayeh, Pia, et al.
(författare)
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Phosphorus Retention in a Newly Constructed Wetland Receiving Agricultural Tile Drainage Water
- 2013
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Ingår i: Journal of Environmental Quality. - : Wiley. - 0047-2425 .- 1537-2537. ; 42, s. 596-605
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Tidskriftsartikel (refereegranskat)abstract
- One measure used in Sweden to mitigate eutrophication of waters is the construction of small wetlands (free water surface wetland for phosphorus retention [P wetlands]) to trap particulate phosphorus (PP) transported in ditches and streams. This study evaluated P retention dynamics in a newly constructed P wetland serving a 26-ha agricultural catchment with clay soil. Flow-proportional composite water samples were collected at the wetland inlet and outlet over 2 yr (2010-2011) and analyzed for total P (TP), dissolved P (DP), particulate P (PP), and total suspended solids (TSS). Both winters had unusually long periods of snow accumulation, and additional time-proportional water samples were frequently collected during snowmelt. Inflow TP and DP concentrations varied greatly (0.02-1.09 mg L-1) during the sampling period. During snowmelt in 2010, there was a daily oscillation in P concentration and water flow in line with air temperature variations. Outflow P concentrations were generally lower than inflow concentrations, with net P losses observed only in August and December 2010. On an annual basis, the wetland acted as a net P sink, with mean specific retention of 69 kg TP, 17 kg DP, and 30 t TSS ha(-1) yr(-1), corresponding to a reduction in losses of 0.22 kg TP ha(-1) yr(-1) from the agricultural catchment. Relative retention was high (36% TP, 9% DP, and 36% TSS), indicating that small constructed wetlands (0.3% of catchment area) can substantially reduce P loads from agricultural clay soils with moderately undulating topography.
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| 7. |
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| 8. |
- Lind, Linus, et al.
(författare)
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Nitrate removal capacity and nitrous oxide production in soil profiles of nitrogen loaded riparian wetlands inferred by laboratory microcosms
- 2013
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Ingår i: Soil Biology and Biochemistry. - : Elsevier. - 0038-0717 .- 1879-3428. ; 60, s. 156-164
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Tidskriftsartikel (refereegranskat)abstract
- Riparian wetlands located in agricultural catchments may often receive a high nitrate (NO3−) load because of the leaching of nutrients derived from upland farming activities. Nitrate can be removed in wetland soils by denitrification which is the reduction of NO3− to the gaseous forms nitrous oxide (N2O) and dinitrogen (N2). However, the release of N2O is detrimental to the environment because N2O is a potent greenhouse gas. Therefore, this study aimed at investigating the factors controlling the production of N2O and at evaluating the risk for N2O emissions from riparian wetland soils. In a laboratory setup, we simulated an upward flow of NO3− enriched groundwater through intact soil cores collected from four wetlands with contrasting soil characteristics. The results showed a rapid reduction of the NO3− fluxes, supporting the effectiveness of wetlands for removal of N. However, during the reduction of NO3− transient accumulation of N2O was observed, but the N2O concentration decreased with declining NO3− availability. In this study, the NO3− load was revealed as the only significant factor controlling both NO3− reduction and N2O production. Our results confirm the capacity of wetlands to remove large amounts of N, but it also showed that substantial emission of N2O might occur if the reduction of NO3− is not complete, a matter to be considered when diverting N rich waters toward wetlands.
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| 9. |
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| 10. |
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| 11. |
- Sundblad-Tonderski, Karin, 1958-
(författare)
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Recycling of wastewater nutrients in a wetland filter
- 1988
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis demonstrates the possibility of using wastewater nutrients for plant biomass production and concomitantly achieving year-round wastewater treatment. As part of a joint research project, the emphasis in this thesis is on nutrient recycling capacity relative to treatment efficiency.An artificial wetland system was studied in experimental field lysimeters. Wastewater was infiltrated into soil planted with reed sweetgrass (Glyceria maxima). In natural stands of this grass, harvesting two or three times per year had a negative impact on biomass yields. This was attributed to a reduced amount of carbohydrates stored in the rhizomes, resulting in the formation of thinner shoots in harvested stands. In contrast to this, high biomass yields were obtained with two harvests per year in the wetland filter.Crop removal of nitrogen and phosphorus amounted to a maximum of 55% and 28% of the amount applied during a growing season. Year-round wastewater application would decrease the relative removal because no plant uptake occurrs during the winter months. However, applied nutrients are also transferred to the soil, thus contributing to the nutrient recycling capacity of the system. This may determine the longevity of a wet! and filter as a method of wastewater treatment, since the soil is gradually saturated with phosphorus. Another factor of importance for the long-term limitations is the observed decrease in soil permeability.Treatment efficiency of phosphorus and BOD7 met the required limits for wastewater emissions in Sweden. An average 60% removal of nitrogen was achieved, which is significantly more than in a conventional tertiary treatment plant. The costs for reaching this treatment level were estimated to be lower for a wet land filter than for the existing treatment systems for urban areas up to 1000 inhabitants. The feasibility for this conceptual change of better resource management with regard to present Swedish wastewater treatment strategy is discussed.
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| 12. |
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| 13. |
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| 14. |
- Van Cleemput, O, et al.
(författare)
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Denitrification in Wetlands
- 2007. - 1
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Ingår i: Biology of the nitrogen cycle. - Amsterdam : Elsevier. - 9780444531087 ; , s. 359-367
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- All organisms require nitrogen to live and grow. The movement of nitrogen between the atmosphere, biosphere, and geosphere in different forms is described by the nitrogen cycle. This book is an activity of the COST 856 Action on Denitrification. It covers all aspects of the N-cycle: chemistry, biology (enzymology, molecular biology), physics, applied aspects (greenhouse effect, N-pollution problems, practices in farming, in waste-water treatment, and more). In this book, leading editors offer the latest research available on dentrification (reduction of nitrates or nitrites commonly by bacteria- as in soil). * Provides details on denitrification and its general role in the environment* Offers latest research in N-Cycle and its reactions* Discusses impacts on various environments: agriculture, wetlands, plants, waste-water treatment and more* The only book available in the field since the last 20 years* Contains 27 chapters written by internationally highly recognized experts in the field* Covers all modern aspects, emphasizes molecular biology and ecology* Written in an easily understandable way
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| 15. |
- Vymazal, J, et al.
(författare)
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Constructed wetlands for wastewater treatment
- 2006
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Ingår i: Wetlands and Natural Resource Management. Ecological Studies. - Berlin : Springer Verlag. - 3540331867 ; , s. 69-96
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Together with its companion, Volume 191 Wetlands: Functioning, Biodiversity Conservation and Restoration, this book provides a broad and well-integrated overview of recent major scientific results in wetland science and their applications in natural resource management issues.After an introduction to the field, a group of internationally known experts summarizes the state of the art on an array of topics, divided into four sections:-The Role of Wetlands for Integrated Water Resources Management: Putting Theory into Practice-Wetland Science for Environmental Management-Wetland Biogeochemistry-Wetlands and Climate Change Worldwide The volume will be useful to wetland scientists and natural resource managers, as well as environmental policy makers at all levels.
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