| 1. |
- Bojcevska, Hristina, 1977-, et al.
(author)
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Free water surface constructed wetlands for polishing sugar factory effluent in western Kenya : macrophyte phosphorus recovery and treatment results
- 2006
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In: Proceedings of the 10th International Conference on Wetland Systems for Water Pollution Control, 23-29 September 2006. - Lisbon : Ministério de Ambiente, do Ordenamento do Territóri e do Desenvolvimento Regional (MAOTDR) and IWA. ; , s. 709-718
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Conference paper (peer-reviewed)abstract
- Wastewater treatment and nitrogen and phosphorus (P) recovery in harvested biomass of two macrophyte species receiving two wastewater loading rates was studied in a free water surface constructed wetland (FWS CW) in Kenya. Half the CWs were planted with Cyperus papyrus and half with Echinochloa pyramidalis. Inlets and outlets water samples were analysed for selected water quality parameters. Macrophytes were harvested at around 7 month intervals on three occasions for determination of biomass, P and N content. Area specific removals of TP, TSS and Nh4+-N were higher in the high-load CWs and in the low-load ones, but the relative removal was lower. For Nh4+-N, there was a significantly higher removal in C. papyrus CWs- Each macrophyte species had similar tissue P content independent of mass load suggesting excess available phosphorus in all CWs, as supported by the low N:P ratios. During a 7 month period, the amount of P stored daily in the green biomass of the macrophytes represented 18-29% and 25-100% of the daily removal of TP and TDP, respectively.
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| 2. |
- Bodin, Hristina, et al.
(author)
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Free water surface constructed wetlands for polishing sugar factory effluent in western Kenya : macrophyte phosphorus recovery and treatment results
- 2006
-
In: Proceedings of the 10th International Conference on Wetland Systems for Water Pollution Control, 23-29 September 2006. ; , s. 709-718
-
Conference paper (peer-reviewed)abstract
- Wastewater treatment and nitrogen and phosphorus (P) recovery in harvested biomass of two macrophyte species receiving two wastewater loading rates was studied in a free water surface constructed wetland (FWS CW) in Kenya. Half the CWs were planted with Cyperus papyrus and half with Echinochloa pyramidalis. Inlets and outlets water samples were analysed for selected water quality parameters. Macrophytes were harvested at around 7 month intervals on three occasions for determination of biomass, P and N content. Area specific removals of TP, TSS and Nh4+-N were higher in the high-load CWs and in the low-load ones, but the relative removal was lower. For Nh4+-N, there was a significantly higher removal in C. papyrus CWs- Each macrophyte species had similar tissue P content independent of mass load suggesting excess available phosphorus in all CWs, as supported by the low N:P ratios. During a 7 month period, the amount of P stored daily in the green biomass of the macrophytes represented 18-29% and 25-100% of the daily removal of TP and TDP, respectively.
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| 3. |
- Sundberg, Carina, 1963-, et al.
(author)
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Overland flow systems for treatment of landfill leachates : Potential nitrification and structure of the ammonia-oxidising bacterial community during a growing season
- 2007
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In: Soil Biology and Biochemistry. - : Elesevire. - 0038-0717 .- 1879-3428. ; 39:1, s. 127-138
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Journal article (peer-reviewed)abstract
- Overland flow systems are useful for treating landfill leachates, because they provide favourable conditions for nitrification and they are easy to maintain. However, little is known about the microbial communities in such systems or the nitrification capacity of those microorganisms. In this study, seasonal variations in potential nitrification and in community composition of nitrifying bacteria were investigated in two overland flow areas receiving leachate from landfills at Korslöt and Hagby, Sweden. Samples were collected in the settling ponds sediment and at two depths in the overland flow areas (the macrophyte litter layer and the rhizosphere) in May, August and November 2003. A short-term incubation method was used to measure potential oxidation of ammonia and nitrite (designated PAO and PNO). The ammonia-oxidising bacterial (AOB) community was investigated using a 16S rRNA gene approach that included PCR amplification and analysis of PCR products by denaturing gradient gel electrophoresis (DGGE), followed by nucleotide sequencing and phylogenetic analysis. PAO was determined in the range 5–2700 (NO2−+NO3−)-N g−1 dw d−1 and PNO in the range 60–2000 μg NO2−-N g−1 dw d−1. At Korslöt, PAO and PNO showed similar temporal variation in the different ecosystems, whereas no such relationship was noticed at Hagby. Considering both sites, there was no obvious change in the composition of the AOB community over the growing season. However, the composition did differ between the ecosystems: Nitrosomonas-like sequences were more common in the ponds, and in the litter layers they were found as often as Nitrosospira-like sequences, whereas Nitrosospira-like sequences were more common in the rhizospheres. Altogether, we found nine different AOB sequences, five Nitrosomonas-like and four Nitrosospira-like, which belonged to clusters 0, 2, 3b, 6a, 6b and 7. There was no apparent relationship between the number of AOB populations and the PAO in different soil layers and sediments.
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| 4. |
- Tonderski, Karin S, et al.
(author)
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Modeling the impact of potential wetlands on phosphorus retention in a Swedish catchment
- 2005
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In: Ambio. - : Royal Swedish Academy of Sciences. - 0044-7447 .- 1654-7209. ; 34:7, s. 544-551
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Journal article (peer-reviewed)abstract
- In southern Sweden, wetlands are constructed to remove nitrogen (N) in agricultural catchments. The possible effects of such wetlands on riverine phosphorus (P) were also estimated using input-output data from three well-monitored wetlands. This was done to formulate a simple model for removal of P that is dependent on inflow characteristics. Next, the N- and P-reducing effects of wetlands were modeled on a catchment scale (1900 km 2) using the HBV-NP model and various assumptions about the wetland area and location. All three wetlands functioned as sinks for total P (tot-P) and for total suspended solids (TSS) with a removal of 10% to 31% and 28% to 50%, respectively. Mean P-removal rates of 17-49 kg ha(-1) yr(-1) were well simulated with the model. Catchment scale simulations indicated that wetlands were more efficient (in percentage of load) as traps for P than for N and that this may motivate the construction of wetlands for P removal far upstream from the catchment outlet.
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| 5. |
- Tonderski, Karin S.
(author)
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Molecular and microbial advances in wetland science
- 2009
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In: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 35:6, s. 959-960
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Journal article (other academic/artistic)abstract
- The 2nd International Symposium on Wetland Pollutant Dynamics and Control (WETPOL 2007) - held 16-20 September 2007 in Tartu, Estonia - provided a forum for exchange of recent results, ideas and methods among researchers studying the cycling of nitrogen, phosphorus, carbon, heavy metals, and organic pollutants in wetlands. The current special issue contains selected papers from the meeting focused on molecular and microbial techniques and processes of importance for substance cycling and pollutant removal in wetlands. It also includes a review of microbial processes in treatment wetlands that gives a good status description of our current knowledge of how different designs and operational conditions affect environmental factors that influence microbial densities, community composition and activities. The editorial paper highlights results from those papers, where the authors have linked process studies with biochemical and gene-based investigations to achieve a mechanistic understanding of observed processes, and/or the biology of the communities responsible for those processes.
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| 6. |
- Weisner, Stefan E.B, et al.
(author)
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Influence of alternative states on nitrogen removal in experimental wetlands
- 2007
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In: 2nd International Symposium on Wetland Pollutant Dynamics and Control - WETPOL 2007. - Tartu : Institute of Geography, University of Tartu. - 9789949116881 ; , s. 357-359
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Conference paper (other academic/artistic)abstract
- Denitrification is the main process that remove nitrate from the water in wetlands. Plants can supply denitrifying bacteria with organic carbon and suitable attachment surfaces (Weisner et al. 1994). They also promote the development of anaerobic conditions through litter accumulation and decomposition, which would favour denitrification. The presence of plants has been shown to enhance nitrate removal in field studies (Bachand and Horne 2000). Toet et al. (2005) found a higher nitrogen removal in wetland compartments with emergent plants than with submersed plants. Results from microcosm studies have shown that the potential for denitrification is specific for different plant species (Bastviken et al. 2005).Wetlands may typically exist in alternative states, dominated by different kinds of vegetation. The purpose of this study was to investigate the effect of alternative state on nitrogen removal under controlled conditions in experimental wetlands.
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