Assessment of clogging phenomena in granular filter media used for stormwater treatment
- Kandra, Harpreet, McCarthy, David, Fletcher, Tim, Deletic, Ana
- Authors: Kandra, Harpreet , McCarthy, David , Fletcher, Tim , Deletic, Ana
- Date: 2014
- Type: Text , Journal article
- Relation: Journal of Hydrology Vol. 512, no. (2014), p. 518-527
- Full Text:
- Reviewed:
- Description: Hydraulic performance of granular filter media and its evolution over time is a key design parameter for stormwater filtration and infiltration systems that are now widely used in management of polluted urban runoff. In fact, clogging of filter media is recognised as the main limiting factor of these stormwater treatment systems. This paper focuses on the effect of physical characteristics of filter media and flow-through rates on the clogging of stormwater filters. Five replicate experimental columns were constructed using zeolite, scoria, riversand and polymeric glass beads, and different flow-through rates were achieved using restricted outlets. The systems were dosed with semi-synthetic stormwater and the evolution of hydraulic performance and sediment removal rate was observed (for four filter media and across four flow rates) to investigate impacts of media type and flow rate. It was found that shape and smoothness of filter media grains had limited effect on clogging and sediment removal rate. All media except scoria clogged after similar volumes of stormwater but scoria-based filters were found to be highly variable in performance, most likely due to breakdown of its particles. Conversely, flow-through rate significantly affected clogging and sediment removal rate. For instance, in the case of zeolite filters, the systems with the lowest flow rate clogged after application of over 30. m of stormwater, while the unrestricted zeolite columns (with 200 times the flow rate) clogged after only 10. m of applied stormwater. At the same time, the zeolite filters with the lowest flow rate had an overall treatment efficiency of 88% compared with the unrestricted design's efficiency of 59%. Further work is needed to analyse the influence of filter bed design, stormwater inflow characteristics and drying and wetting regimes on clogging and to understand the location of the clogged material in these filters. © 2014 Elsevier B.V.
- Authors: Kandra, Harpreet , McCarthy, David , Fletcher, Tim , Deletic, Ana
- Date: 2014
- Type: Text , Journal article
- Relation: Journal of Hydrology Vol. 512, no. (2014), p. 518-527
- Full Text:
- Reviewed:
- Description: Hydraulic performance of granular filter media and its evolution over time is a key design parameter for stormwater filtration and infiltration systems that are now widely used in management of polluted urban runoff. In fact, clogging of filter media is recognised as the main limiting factor of these stormwater treatment systems. This paper focuses on the effect of physical characteristics of filter media and flow-through rates on the clogging of stormwater filters. Five replicate experimental columns were constructed using zeolite, scoria, riversand and polymeric glass beads, and different flow-through rates were achieved using restricted outlets. The systems were dosed with semi-synthetic stormwater and the evolution of hydraulic performance and sediment removal rate was observed (for four filter media and across four flow rates) to investigate impacts of media type and flow rate. It was found that shape and smoothness of filter media grains had limited effect on clogging and sediment removal rate. All media except scoria clogged after similar volumes of stormwater but scoria-based filters were found to be highly variable in performance, most likely due to breakdown of its particles. Conversely, flow-through rate significantly affected clogging and sediment removal rate. For instance, in the case of zeolite filters, the systems with the lowest flow rate clogged after application of over 30. m of stormwater, while the unrestricted zeolite columns (with 200 times the flow rate) clogged after only 10. m of applied stormwater. At the same time, the zeolite filters with the lowest flow rate had an overall treatment efficiency of 88% compared with the unrestricted design's efficiency of 59%. Further work is needed to analyse the influence of filter bed design, stormwater inflow characteristics and drying and wetting regimes on clogging and to understand the location of the clogged material in these filters. © 2014 Elsevier B.V.
Phenological studies in Australia: Potential application in historical and future climate analysis
- Keatley, Marie, Fletcher, Tim, Hudson, Irene, Ades, Peter
- Authors: Keatley, Marie , Fletcher, Tim , Hudson, Irene , Ades, Peter
- Date: 2002
- Type: Text , Journal article
- Relation: International Journal of Climatology Vol. 22, no. 14 (Nov 2002), p. 1769-1780
- Full Text:
- Reviewed:
- Description: Phenological observations of eucalypts (Myrtaceae) were undertaken in four Australian states (New South Wales, Queensland, Victoria, and Western Australia) from the late 1920s until the early 1980s, by the respective State Forest Commissions. Unfortunately, few records have survived. For Victoria, surviving records encompass 42 forest districts, covering from less than 2 years to 42 years, and approximately 50 species. This paper concentrates on the flowering of four competing species (Eucalyptus leucoxylon, E. microcarpa, E. polyanthemos, and E. tricarpa) over 23 years (1940-62) from Maryborough, Victoria, recorded on a monthly basis by one observer over the period. This study represents one of the first attempts to utilize Australian phenological data to detect responses to climate change. There were no significant trends (P = 0.05) over time in the mean flowering commencement date. Forward stepwise regression found a significant relationship between temperature and flowering commencement in two species (E. leucoxylon: R-2 = 0.42, P < 0.01; E. polyanthemos: R-2 = 0.47, P = 0.02). Rainfall also had a significant influence on flowering commencement in E. tricarpa (R-2 = 0.60, P < 0.01), E. leucoxylon (R-2 = 0.43, P = 0.02) and E. polyanthemos (R-2 = 0.24, P < 0.01). The combination of temperature and rainfall (with temperature exerting the greatest influence), however, was significant for all species and had the most explanatory power (ranging from R-2 = 0.74 to 0.85, P < 0.01). Overall, in response to predicted increases in temperature and summer rainfall, E. leucoxylon and E. tricarpa would commence flowering later. In E. polyanthemos and E. microcarpa, increased temperature and rainfall will result in an earlier onset of flowering. Copyright (C) 2002 Royal Meteorological Society.
- Description: 2003000171
- Authors: Keatley, Marie , Fletcher, Tim , Hudson, Irene , Ades, Peter
- Date: 2002
- Type: Text , Journal article
- Relation: International Journal of Climatology Vol. 22, no. 14 (Nov 2002), p. 1769-1780
- Full Text:
- Reviewed:
- Description: Phenological observations of eucalypts (Myrtaceae) were undertaken in four Australian states (New South Wales, Queensland, Victoria, and Western Australia) from the late 1920s until the early 1980s, by the respective State Forest Commissions. Unfortunately, few records have survived. For Victoria, surviving records encompass 42 forest districts, covering from less than 2 years to 42 years, and approximately 50 species. This paper concentrates on the flowering of four competing species (Eucalyptus leucoxylon, E. microcarpa, E. polyanthemos, and E. tricarpa) over 23 years (1940-62) from Maryborough, Victoria, recorded on a monthly basis by one observer over the period. This study represents one of the first attempts to utilize Australian phenological data to detect responses to climate change. There were no significant trends (P = 0.05) over time in the mean flowering commencement date. Forward stepwise regression found a significant relationship between temperature and flowering commencement in two species (E. leucoxylon: R-2 = 0.42, P < 0.01; E. polyanthemos: R-2 = 0.47, P = 0.02). Rainfall also had a significant influence on flowering commencement in E. tricarpa (R-2 = 0.60, P < 0.01), E. leucoxylon (R-2 = 0.43, P = 0.02) and E. polyanthemos (R-2 = 0.24, P < 0.01). The combination of temperature and rainfall (with temperature exerting the greatest influence), however, was significant for all species and had the most explanatory power (ranging from R-2 = 0.74 to 0.85, P < 0.01). Overall, in response to predicted increases in temperature and summer rainfall, E. leucoxylon and E. tricarpa would commence flowering later. In E. polyanthemos and E. microcarpa, increased temperature and rainfall will result in an earlier onset of flowering. Copyright (C) 2002 Royal Meteorological Society.
- Description: 2003000171
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