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| 2. |
- German, Jonas, 1972, et al.
(författare)
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Modelling of different measures for improving removal in a stormwater pond
- 2004
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Ingår i: Proceedings of the 6th international conference on Urban Drainage Modelling. ; , s. 477-484
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Konferensbidrag (refereegranskat)abstract
- The effect on removal efficiency and hydraulic performance of retrofitting an existing pond was modelled using the commercial software Mike21 and compartmental modelling. The Mike21 model had previously been calibrated on the studied pond. Installation of baffles, the addition of culverts under a causeway and removal of an existing island were all studied as possible improvement measures in the pond. The subsequent effect on hydraulic performance and removal of suspended solids was then evaluated. Copper, cadmium, BOD, nitrogen and phosphorous removal were also investigated for the improvement measure showing the best results. Outcomes of this study reveal that all measures increase the removal efficiency of suspended solids. The hydraulic efficiency is improved for all cases, except for the case where the island is removed. Compartmental modelling was also used to evaluate hydraulic performance and facilitated a better understanding of the way each of the different measures affected the flow pattern and performance. It was concluded that the installation of baffles is the best of the studied measures resulting in a reduction in the annual load on the receiving lake by approximately 8,000 kg of suspended solids, 2 kg of copper and 600 kg of BOD.
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| 3. |
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| 4. |
- German, Jonas, 1972
(författare)
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Reducing Stormwater Pollution - Performance of Retention Ponds and Street Sweeping
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stormwater, in this study defined as surface runoff in urban areas, is known to transport large quantities of toxic substances to receiving waters. Therefore different practices to treat stormwater have been proposed. In Sweden retention ponds have become a common treatment method during the past decade. The main objective of the study is to investigate the performance of stormwater ponds and street sweeping. Performance of retention ponds was investigated by field measurements of water and sediments, and through simulation of hydrodynamics and removal processes. This showed that ponds are an efficient way of reducing pollutant loads from stormwater and that both water and sediment were highly polluted. A clear correlation between pollutant concentrations in the water and in sediments was found, which indicates that pond sediments can be used for characterising pollutant loads from urban catchments. In order to distinguish between different parameters affecting removal efficiency in ponds, simulations using a numerical model were done. This demonstrated that surface load is the most important parameter governing removal efficiency, however hydraulic efficiency, i.e. how efficient the volume of the pond is utilised, has for engineering purposes a crucial significance, since the space available for construction normally is limited. Further it was shown that the most important factor explaining changes in removal efficiencies between winter and summer seasons is the change of hydrology during the winter. Wind was found to be an important parameter governing oxygenation of ponds. In order to investigate the efficiency of street sweeping a street was swept and the amount of removed sediment and heavy metals were measured. This showed that street sweeping could be an efficient control measure of pollutants. The amount of sediments on the street decreased during the sweeping period and approached a steady state condition. The largest amounts of metals were found in the sandy fractions of the sediment, however the highest concentrations were found in the finest grain sizes and the concentrations were proportional to the inverse of the particle diameter. Copper was found to be the critical pollutant for stormwater and sediments from ponds and streets.
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| 5. |
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| 6. |
- German, Jonas, 1972, et al.
(författare)
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Street sweeping as a pollutant control measure
- 2001
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Ingår i: Proceedings of the 4th international conference on innovative technologies in urban drainage, Lyon, France, June 25-27. ; 1, s. 383-390
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Konferensbidrag (refereegranskat)abstract
- Street weeping is an interesting non-structural method to decrease the pollutant load to stormwater. In this paper a study of street sweeping performance is presented. A test section of a street was swept once a week during three weeks and once every workday during another three week period. The amount of removed sediment was measured and the sediments were measured for heavy metals. During the test period 84.5 kg of sediment was removed from the street, which corresponds to 4 g of copper and zinc, 0.9 g of chromium, 0.6 g of lead and 0.4 g of nickel. During the everyday sweeping period the amount of sediment in the street decreased exponentially and approached a steady state condition. The weather during the period was dry, which meant that the effect of the street sweeping on the stormwater quality could not be measured.
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| 7. |
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| 8. |
- German, Jonas, 1972, et al.
(författare)
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The relation between stormwater and sediment quality in stormwater ponds
- 2002
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Ingår i: Strecker, E. W. and Huber, W. C., Proceedings of the 9th International Conference on Urban Drainage, Portland, Oregon, USA, September 8-13. - 0784406448
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Konferensbidrag (refereegranskat)
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| 9. |
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| 10. |
- Jansons, Ketah, et al.
(författare)
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Evaluating the Impact of Imperfect Mixing on the Performance of Stormwater Treatment Ponds
- 2004
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Ingår i: International Conference on Water Sensitive Urban Design: Cities As Catchments. - 1876346523 ; , s. 471-479
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Konferensbidrag (refereegranskat)abstract
- The impact of imperfect mixing on the performance of two full-scale stormwater treatment ponds was evaluated using compartmental modelling. The hydrodynamic component of the model consists of a series of appropriately interconnected well mixed tanks and is proposed as the simplest model capable of accurately describing the behaviour of a system with hydrodynamic characteristics such as short-circuiting, recycling and stagnation. A kinetic model incorporating first order removal of total suspended solids (TSS) was linked to the simple hydrodynamic model to evaluate performance. Model validation was carried out using experimental tracer response data and two dimensional simulated flow patterns. Results obtained reveal a significant reduction in TSS removal as a result of imperfect mixing. This study highlights the usefulness of relatively simple compartmental models as a tool for evaluating the impact of imperfect mixing on the performance of stormwater treatment ponds.
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| 11. |
- Jansons, K., et al.
(författare)
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Modelling of different measures for improving removal in a storm pond
- 2005
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Ingår i: Water Science and Technology. - 0273-1223. ; 52:5, s. 105-112
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Tidskriftsartikel (refereegranskat)abstract
- The effect of retrofitting an existing pond on removal efficiency and hydraulic performance was modelled using the commercial software Mike21 and compartmental modelling. The Mike21 model had previously been calibrated on the studied pond. Installation of baffles, the addition of culverts under a causeway and removal of an existing island were all studied as possible improvement measures in the pond. The subsequent effect on hydraulic performance and removal of. suspended solids was then evaluated. Copper, cadmium, BOD, nitrogen and phosphorus removal were,also investigated for that specific improvement measure showing the best results. Outcomes of this study reveal that all measures increase the removal efficiency of suspended solids. The hydraulic efficiency is improved for all cases, except for the case where the island is removed. Compartmental modelling was also used to evaluate hydraulic performance and facilitated a better understanding of the way each of the different measures affected the flow pattern and performance. It was concluded that the installation of baffles is the best of the studied measures resulting in a reduction in the annual load on the receiving lake by approximately 8,000 kg of suspended solids (25% reduction of the annual load), 2 kg of copper (10% reduction of the annual load) and 600 kg of BOD (10% reduction of the annual load).
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| 12. |
- Pettersson, Thomas, 1966, et al.
(författare)
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Modelling of flow pattern and particle removal in an open stormwater detention pond
- 1998
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Ingår i: In: Proc. HydraStorm’98, Adelaide, Australia, 27-30 September 1998. ; , s. 63-68
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Konferensbidrag (refereegranskat)abstract
- In Sweden open stormwater detention ponds are more often used to reduce stormwater pollution through sedimentation. The pollution reduction occurs both during storm events and in between events. Design methods are often simplified and based on detention time only. However, not only the pond volume but also the geometry and thus the flow pattern are of concern when designing open detention ponds. In the city of Göteborg a 6200 m2 open stormwater detention pond was investigated with respect to massflows of pollutants and flow pattern. The observed data has been used to verify a FEM model established for the pond. Both 3-D and 2-D flow simulations have been performed at inflows starting at 20 l/s up to a maximum of 800 l/s. The simulations show that both 2-D and 3-D calculations give reasonable agreement with observed data. The 3-D calculations are however more accurate taking the bottom shape into account. Conclusions drawn from this study is that simulations of pond flow pattern are essential in designing pond geometry, and inlet and outlet locations.
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| 13. |
- Pettersson, Thomas, 1966, et al.
(författare)
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Pollutant removal efficiency in two stormwater ponds in Sweden
- 1999
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Ingår i: In: Proc. 8th International Conference on Urban Storm Drainage, Sydney, Australia, 30 August-3 September 1999. ; 2, s. 866-873
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Konferensbidrag (refereegranskat)abstract
- Open stormwater ponds have been frequently addressed as a method for treatment of stormwater since measurements show a considerable pollutant removal effect. Pollutant removal efficiency in two stormwater ponds in Sweden is studied where field measurements of inflow and outflow pollutant loads for several successive storm events are described. Cumulative effects of inflow and outflow pollutant discharges are studied and for the outflow a strong correlation to constant outflow pollutant discharges appears that indicate an independence of inflow pollutant load for the two ponds. Hereby, it becomes possible to extrapolate the annual loads from the ponds to the receiving waters of studied pollutants. The specific pond area (m2/ha) is 20 times larger in one of the ponds, which affect the pollutant removal efficiencies. A comparison between specific pond area and pollutant removal efficiency gave that the removal efficiency increases up to a certain level of surface/impervious area, 250 m2/ha, and above this level the increase is not as significant as below. Another factor that has an impact on the removal efficiency is the pond geometry.
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| 14. |
- Vikström, Maria, et al.
(författare)
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Dagvattendammars avskiljningsförmåga – påverkande faktorer och metodik för bedömning
- 2004
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Rapporten beskriver hur numeriska modeller, främst MIKE 21, använts för att ta fram en generell beräkningsmetodik för bedömning av dagvattendammars avskiljningsförmåga. En modellbaserad fallstudie har genomförts för att studera de påverkansfaktorer som styr avskiljningen i en dagvattendamm.
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