| 1. |
- Bojcevska, Hristina, 1977-, et al.
(författare)
-
Free water surface constructed wetlands for polishing sugar factory effluent in western Kenya : macrophyte phosphorus recovery and treatment results
- 2006
-
Ingår i: 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
-
Konferensbidrag (refereegranskat)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.
|
|
| 2. |
- Johannesson, Karin M., 1982-, et al.
(författare)
-
Clay-bound phosphorus retention in wetlands : a catchment comparison
- 2010
-
Ingår i: 6th International Phosphorus Workshop (IPW6). ; , s. 127-127
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Ten constructed wetlands, situated in agricultural areas in the south of Sweden, are investigated for phosphorus (P) retention and factors affecting the efficiency. These wetlands are situated in areas dominated by clay or heavy clay soils. National monitoring and estimations have shown that agricultural areas dominated by such clay soils have among the highest phosphorus losses. It has also been shown that a large proportion of P is transported in particulate form; hence, it is expected that sedimentation is the predominant P retention process in the selected wetlands. Sedimentation of clay may, however, be difficult to achieve in wetlands, and the aim of the study is to quantify the function of wetlands as sinks for the P lost from the catchments. Sedimentation and accumulation of particles are measured once a year using sedimentation plates (40×40 cm) placed on the bottom of the wetlands. Additional sedimentation traps (estimating gross sedimentation) have been placed in three of the wetlands, and those are emptied two times per year. This paper presents results for P and soil retention after the first year (in kg P ha-1 year-1), estimated by extrapolating the amount of sediment accumulated on the plates, and the content of total phosphorus (TP), to the whole wetland area. Furthermore, one wetland was selected for a detailed investigation of the effect of a vegetation filter, which in a previous study has been shown to have a positive effect on particle retention. Here, estimates of net and gross sedimentation are measured before, within and after the vegetation filter. To identify some factors of significant importance for wetland P load and retention efficiency, the statistical relationship with different wetland and catchment characteristics is analyzed. The factors included are the ratio wetland area to catchment area, average hydraulic load, and various catchment characteristics, e.g. soil type, topography, fertilization history, and soil P fractions. Since there is some uncertainty regarding sedimentation of fine clay particles (< 0.2 m), the size fractions of the accumulated sediment is determined to see whether or not the finest clay particles from the catchments settle in the wetlands. Previous studies have shown a correlation between particle size and bioavailability, where finer clay particles contain larger proportion of easily available P. Trapping the finest clay particles is therefore of particular ecological importance and needs to be further investigated.
|
|
| 3. |
- Johannesson, Karin, 1982-, et al.
(författare)
-
Temporal phosphorus dynamics affecting retention estimates in agricultural constructed wetlands
- 2017
-
Ingår i: Ecological Engineering. - Amsterdam : Elsevier. - 0925-8574 .- 1872-6992. ; 103, s. 436-445
-
Tidskriftsartikel (refereegranskat)abstract
- Data from seven constructed wetlands (CWs) in the south of Sweden were analyzed to investigate the effects of water flow and season on inflow phosphorus (P) concentrations and temporal P retention variations in CWs receiving runoff from arable land. The form of P (dissolved or particulate) during different water flows (high and low) and seasons (warm and cold) was investigated using the results of total P (TP) and phosphate analyzed in grab samples that had been collected regularly or occasionally during two to nine years, along with continuous water flow measurements.The form of inflow and outflow P (particulate or dissolved P) differed between CWs, and also varied with season and flow. For instance, in three of the CWs, particulate P (PP) dominated the inflow during the cold period with high flow, while during the other periods the proportion of PP was approximately 50%. In one CW situated in a catchment with high clay content, PP dominated both inflow and outflow at all times. The average clay content in catchment top soils was positively correlated to the flow-weighted inflow TP concentrations.In three CWs receiving runoff through drainage pipes, the relationship between TP concentrations (TPin) and water flow was positive, both during high and low flow, and during warm and cold period. However, in four CWs that received surface water runoff, the relationship between TPin and water flow was positive during high flow periods (i.e. the 25% sampling occasions with the highest flow), and during low flow and warm period, the relationship was negative in these four wetlands, indicating either anoxic stagnant water upstream or influence from rural wastewater.The temporal dynamics of P concentrations mean that in some of the CWs, the main part of the annual P retention may occur during a few days with high water flows. The correlation between concentration and water flow suggests that the water sampling strategy may have a considerable impact on retention estimates, as exemplified by some calculation examples.
|
|
| 4. |
- Akram, Usman, et al.
(författare)
-
Optimizing Nutrient Recycling From Excreta in Sweden and Pakistan : Higher Spatial Resolution Makes Transportation More Attractive
- 2019
-
Ingår i: Frontiers in Sustainable Food Systems. - : Frontiers Media SA. - 2571-581X. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- Recycling essential plant nutrients like nitrogen (N), phosphorus (P), and potassium (K) from organic waste such as human and animal excreta will be an essential part of sustainable food systems and a circular economy. However, transportation is often cited as a major barrier to increased recycling as organic waste is heavy and bulky, and distances between areas of abundant waste may be far from areas with a need for fertilizers. We investigated the effect of increased input data spatial resolution to an optimization model on the weight, distance, and spatial patterns of transport. The model was run in Sweden and in Pakistan to examine cost-effectiveness of transporting excess excreta to areas of crop need after local recycling. Increasing the resolution of input data from political boundaries (municipalities and districts) to 0.083 decimal grids increased the amount of N requiring transport by 12% in Pakistan and increased P requiring transport by 14% in Sweden. The average distance decreased by 67% (to 44 km) in Pakistan but increased by 1 km in Sweden. Further increasing the resolution to 5 km grids in Sweden decreased the average transportation distance by 9 km (down to 123 km). In both countries, increasing resolution also decreased the number of long-distance heavy transports, and as such costs did not increase as much as total distance and weight transported. Ultimately, transportation in Pakistan seemed financially beneficial: the cost of transport only represented 13% of the NPK fertilizer value transported, and total recycling could even cover 78% of additional fertilizer purchases required. In Sweden, the cost of transporting excreta did not seem cost effective without valuing other potential benefits of increased recycling: costs were three times higher than the fertilizer value transported in excreta at the 5 km resolution. In summary, increasing input data resolution created a more realistic picture of recycling needs. This also highlighted more favorable cost to fertilizer value ratios which could make it easier to move forward with industry and government partners to facilitate productive recycling. Our analysis shows that in both countries increased recycling can result in better spatial nutrient balances.
|
|
| 5. |
- Bodin, Hristina, et al.
(författare)
-
Free water surface constructed wetlands for polishing sugar factory effluent in western Kenya : macrophyte phosphorus recovery and treatment results
- 2006
-
Ingår i: Proceedings of the 10th International Conference on Wetland Systems for Water Pollution Control, 23-29 September 2006. ; , s. 709-718
-
Konferensbidrag (refereegranskat)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.
|
|
| 6. |
- Bojcevska, Hristina, et al.
(författare)
-
Free water surface constructed wetlands for polishing sugar factory effluent in western Kenya - macrophyte phosporus recovery and treatment results
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Phosphorus removal and uptake by two macrophyte species receiving two wastewater loading rates was studied in a free water surface constructed wetland system (FWS CW) in Kenya. Half the CWs were planted with Cyperus papyrus and half with Echinochloa pyramidalis. Inlet and outlet water samples were analyzed for selected water quality parameters. The first macrophyte harvest for determination of biomass, P and N content was done after 21 months of operation, followed by two harvests with 7 months intervals. Mass reductions of TP and TDP were higher in the low-load CWs than in the high-load ones. Each macrophyte species had similar tissue P content independent of mass load suggesting excess available phosphorus in all CWs (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. Still, the CW system was not functioning at optimal conditions for simultaneous wastewater treatment and P recovery. Frequent harvesting along with an enlargement of the CW area would yield higher relative nutrient removal rates, and increase the biomass that could be used by local communities for animal fodder and building material.
|
|
| 7. |
- Metson, Genevieve S., 1988-, et al.
(författare)
-
Optimizing transport to maximize nutrient recycling and green energy recovery
- 2020
-
Ingår i: Resources, Conservation & Recycling: X. - : Elsevier. - 2590-289X. ; 9-10
-
Tidskriftsartikel (refereegranskat)abstract
- A circular biobased economy must be able to sustainably manage multiple resources simultaneously. Nutrient (nitrogen, phosphorus, and potassium) recycling and renewable energy production (biogas) can be compatible practices but require substantial transport of heavy organic waste. We combine a spatial optimization model and Life Cycle Assessment (LCA) to explore how Sweden could maximize its use of excreta resources. We use 10×10 km2 resolution data on the location of animal and human excreta and crop demand and model both optimal biogas plant locations and transport of nutrients to and from these plants. Each type of biogas plant (given 4 realistic mixes of excreta) is then evaluated for global warming potential, primary energy use and financial resource costs. Moving excreta through biogas plants, as opposed to simply reapplying on fields, to meet crop nutrient demands comes at a similar cost but the climate and primary energy savings are substantial. As much as 91% of phosphorus and 44% of nitrogen crop demand could be met via optimally transported excreta and the country would avoid about 1 450 kt of CO2-eq, save 3.6 TWh (13 000 tera-joules) of primary energy, and save 90 million euros per year. Substituting mineral fertilizers with recycled nutrients results in savings across all indicators, but the added energy and avoided greenhouse gas emissions associated with biogas production make a large difference in the attractiveness of nutrient recycling. Although the numeric values are theoretical, our results indicate that carefully coordinated and supported biogas production could help maximize multi-resource benefits.
|
|
| 8. |
|
|
| 9. |
- Reusch, T. B. H., et al.
(författare)
-
The Baltic Sea as a time machine for the future coastal ocean
- 2018
-
Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 4:5
-
Tidskriftsartikel (refereegranskat)abstract
- Coastal global oceans are expected to undergo drastic changes driven by climate change and increasing anthropogenic pressures in coming decades. Predicting specific future conditions and assessing the best management strategies to maintain ecosystem integrity and sustainable resource use are difficult, because of multiple interacting pressures, uncertain projections, and a lack of test cases for management. We argue that the Baltic Sea can serve as a time machine to study consequences and mitigation of future coastal perturbations, due to its unique combination of an early history of multistressor disturbance and ecosystem deterioration and early implementation of cross-border environmental management to address these problems. The Baltic Sea also stands out in providing a strong scientific foundation and accessibility to long-term data series that provide a unique opportunity to assess the efficacy of management actions to address the breakdown of ecosystem functions. Trend reversals such as the return of top predators, recovering fish stocks, and reduced input of nutrient and harmful substances could be achieved only by implementing an international, cooperative governance structure transcending its complex multistate policy setting, with integrated management of watershed and sea. The Baltic Sea also demonstrates how rapidly progressing global pressures, particularly warming of Baltic waters and the surrounding catchment area, can offset the efficacy of current management approaches. This situation calls for management that is (i) conservative to provide a buffer against regionally unmanageable global perturbations, (ii) adaptive to react to new management challenges, and, ultimately, (iii) multisectorial and integrative to address conflicts associated with economic trade-offs.
|
|
| 10. |
- Sundberg, Carina, 1963-, et al.
(författare)
-
Overland flow systems for treatment of landfill leachates : Potential nitrification and structure of the ammonia-oxidising bacterial community during a growing season
- 2007
-
Ingår i: Soil Biology and Biochemistry. - : Elesevire. - 0038-0717 .- 1879-3428. ; 39:1, s. 127-138
-
Tidskriftsartikel (refereegranskat)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.
|
|
