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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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| 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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