| 1. |
- Blecken, Godecke-Tobias, et al.
(författare)
-
Biofilter treatment of stormwater : temperature influence on the removal of nutrients
- 2007
-
Ingår i: Techniques et stratégies durables pour la gestion des eaux urbaines par temps de pluie. - Villeurbanne : Graie. - 9782950933775
-
Konferensbidrag (refereegranskat)abstract
- Nutrients can cause eutrophication of natural water bodies. Thus, urban stormwater which is an important nutrient source has to be treated in order to reduce its nutrient loads. Biofilters which use media, biofilms and plants, are a good treatment option regarding nutrients. This paper presents the results of a biofilter column study in cold temperatures (+2°C, +8°C, control at +20°C) which may cause special problems regarding the biofilter performance. It was shown that particle bound pollutants as TSS and a high fraction of phosphorus were reduced well without being negatively influenced by cold temperatures. Nitrogen, however, was not reduced; especially NOx was produced in the columns which can be explained with both insufficient denitrification and high leaching from the columns.
|
|
| 2. |
- Blecken, Godecke-Tobias, et al.
(författare)
-
The influence of temperature on nutrient treatment efficiency in stormwater biofilter systems
- 2007
-
Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 56:10, s. 83-91
-
Tidskriftsartikel (refereegranskat)abstract
- Nutrients can cause eutrophication of natural water bodies. Thus, urban stormwater which is an important nutrient source in urbanised areas has to be treated in order to reduce its nutrient loads. Biofilters which use soil filter media, biofilms and plants, are a good treatment option for nutrients. This paper presents the results of a biofilter column study in cold temperatures (+2 °C, +8 °C, control at +20 °C) which may cause special problems regarding biofilter performance. It was shown that particle-bound pollutants as TSS and a high fraction of phosphorus were reduced well without being negatively influenced by cold temperatures. Nitrogen, however, was not reduced; especially NOx was produced in the columns. This behaviour can be explained with both insufficient denitrification and high leaching from the columns
|
|
| 3. |
- Broekhuizen, Ico, et al.
(författare)
-
Urban drainage models for green areas : Structural differences and their effects on simulated runoff
- 2019
-
Ingår i: Journal of Hydrology X. - : Elsevier. - 2589-9155. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- Mathematical stormwater models are often used as tools for planning and analysing urban drainage systems. However, the inherent uncertainties of the models must be properly understood in order to make optimal use of them. One source of uncertainty that has received relatively little attention, particularly for increasingly popular green areas as part of urban drainage systems, is the mathematical model structure. This paper analyses the differences between three different widely-used models (SWMM, MOUSE and Mike SHE) when simulating rainfall runoff from green areas over a 26-year period. Eleven different soil types and six different soil depths were used to investigate the sensitivity of the models to changes in both. Important hydrological factors such as seasonal runoff and evapotranspiration, the number of events that generated runoff, and the initial conditions for rainfall events, varied significantly between the three models. MOUSE generated the highest runoff volumes, while it was rather insensitive to changes in soil type and depth. Mike SHE was mainly sensitive to changes in soil type. SWMM, which generated the least runoff, was sensitive to changes in both soil type and depth. Explanations for the observed differences were found in the descriptions of the mathematical models. The differences in model outputs could significantly impact the conclusions from studies on the design or analysis of urban drainage systems. The amount and frequency of runoff from green areas in all three models indicates that green areas cannot be simply ignored in urban drainage modelling studies.
|
|
| 4. |
- Muthanna, Tone M., et al.
(författare)
-
An evaluation of applying existing bioretention sizing methods to cold climates with snow storage conditions
- 2007
-
Ingår i: Techniques et stratégies durables pour la gestion des eaux urbaines par temps de pluie. - Villeurbanne : Graie. - 2950933793 ; 56:10, s. 73-81
-
Konferensbidrag (refereegranskat)abstract
- Eight of the current sizing and design methods proposed for bioretention facilities were evaluated for rainfall runoff and snow storage volumes for a costal cold climate in Trondheim, Norway. The RECARGA bioretention infiltration model was used to compare the performance of the methods using 10 months of observed data from a pilot scale bioretention box. The surface areas, total ponding time, number and duration of overflow events, and snow storage volumes were compared. It was found that even in a costal cold climate with several intermittent melt cycles the snow storage requirements were an important design parameter, and if more than 25% of the total snow volume should stored this became the deciding design parameter.
|
|
| 5. |
- Muthanna, Tone M., et al.
(författare)
-
Heavy metal removal in cold climate bioretention
- 2007
-
Ingår i: Water, Air and Soil Pollution. - : Springer Science and Business Media LLC. - 0049-6979 .- 1573-2932. ; 183:1-4, s. 391-402
-
Tidskriftsartikel (refereegranskat)abstract
- A bioretention media is a stormwater treatment option designed to reduce peak runoff volumes and improve water quality through soil infiltration and plant mitigation. To investigate the heavy metal removal in a bioretention media in a cold climate setting, a small pilot sized bioretention box was built in Trondheim, Norway. The system was sized using the Prince Georges County bioretention design method from 1993. Three runoff events, created using historical data, were undertaken in April 2005 and then again in August 2005. Both the peak flow reduction and the total volume reduction were significantly lower in April compared to August. Peak flow reduction was 13% in April versus 26% in August and the total volume reduction was 13% in April versus 25% in August. Metal retention was good for both seasons with 90% mass reduction of zinc, 82% mass reduction of lead and 72% mass reduction of copper. Plant uptake of metals was documented between 2 to 7%; however adsorption and mechanical filtration through the mulch and soil column were the most dominant metal retention processes. The metal retention was independent of the selected hydraulic loading rates (equivalent to 1.4–7.5 mm h−1 precipitation) showing that variable inflow rates during this set of events did not affect the treatment efficiency of the system.
|
|
| 6. |
- Muthanna, Tone M., et al.
(författare)
-
Seasonal climatic effects on the hydrology of a rain garden
- 2008
-
Ingår i: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 22:11, s. 1640-1649
-
Tidskriftsartikel (refereegranskat)abstract
- paper evaluates the performance and winter hydrology of two small-scale rain gardens in a cold climate coastal area in Trondheim, Norway. One rain garden received runoff from a small residential watershed over a 20 month study period while the second rain garden with a shorter study period of 7 months was used as a control. The objective of the study was to investigate the extent to which cold climatic conditions would influence the hydrology and performance of the rain gardens. The hydraulic detention, storm lag time and peak flow reduction were measured and compared seasonally. No significant difference between seasonal lag time could be found, but there was a clear decreasing trend in lag time between rain, rain-on-snow and snowmelt. The average peak flow reduction for 44 storms in the study period was 42% compared to 27% for the winter seasons, indicating that the performance of the rain garden is reduced in the cold season (below 0 °C). The average hydraulic detention time for the rain garden was 0·84 ( ± 0·73) with runoff inflow and 1·91 ( ± 3·1) with only precipitation. A strong positive correlation was found between the time since the last wetting event and lag time, and between air temperature and hydraulic detention. This indicates that the time between events and seasonal air temperatures are key parameters in the hydraulic performance of cold climate rain gardens. The rain gardens were not used for snow storage areas, and a volume requirement for this was not evaluated in the study.
|
|
