Filtration Technologies for Stormwater Harvesting

(2004 – 2007)
Belinda Hatt

Storm runoff from urban areas degrades urban waterways and receiving waters. Population, industrial growth and climate change further affect freshwater supplies. Stormwater harvesting can augment potable water supplies, improve urban aquatic ecosystems and enhance sustainability. Lack of reliable, affordable treatment technologies has impeded widespread adoption of stormwater harvesting. This thesis examined hydraulic and pollutant removal capabilities of three types of stormwater filtration filters (gravel, non-vegetated fine media and vegetated) through laboratory and field studies with a view to improving design.

Assessment, under various hydrologic regimes, showed that these filters reduce concentrations of suspended solids and particulate-bound pollutants. Nutrient removal was variable, declining in aging filters, particularly with nitrogen. Gravel filters are vulnerable to clogging at the bottom of the profile, complicating maintenance, yet suitable for irrigation. Six different non-vegetated fine filter media types were tested at laboratory scale and found to improve pollutant removal; clogging occurred at the filter surface, simplifying management, while compaction of filter media assisted infiltration. Variable wetting and drying regimes influenced hydraulic and treatment performance; extended dry periods had a detrimental impact on nitrogen retention; inappropriate soil caused leaching of nutrients. A study of three field-scale vegetated stormwater filtration systems (biofilters) showed that they promoted physical, chemical and biological processes for pollutant removal, boosting protection against compaction and clogging, also reducing runoff volumes and peak flows. Biofiltration-treated stormwater suits irrigation, non-contact recreation, and nearly indoor use, though as with non-vegetated fine media filters, wetting and drying reduces performance. The main design recommendation is that stormwater harvesting filters need a fine medium and vegetation. Aesthetic benefits are a further advantage.

Click here to read the abstract of this PhD – PDF (0.2MB)

Project Partners:
This research was supported by industry partners of FAWB & Queensland EPA

Supervisors:
Prof Tim Fletcher and Prof Ana Deletic

Publication:
Hatt B.E. (2007) Filtration Technologies for Stormwater Harvesting. PhD Thesis, Department of Civil Engineering, Monash University.

Other publications (link)

Links:
Vegetated Filtration Systems/BiofiltersWSUD Technologies
Non-Vegetated Filtration Systems/BiofiltersWSUD Technologies