Biofiltration
What is biofiltration?
Biofiltration is a widely used technique in the removal of pollutants, sediments, heavy metals and other organic and non-organic elements from transient water. The water passes through a series of stages. The number of stages required will vary depending on the volume of water to be treated. Generally the water treated, in a biofiltration system, is either waste water or storm water. Each stage of the system consists of varying types of permeable growing medium and distinctively chosen plant species to remove these elements from the water – ultimately cleaning the water as it passes through the system.
Which plant species are commonly used?
Selecting plant species, such as Ficinia nodosa, Juncus kraussii and Bolboscheonus caldwellii, will assist in removing up to 70% of nutrients (which is taken up by the plant species) and around 80% of sediments and heavy metals (which is trapped by the medium and additional optional infrastructure). As the water percolates through the different layers of medium, the sediments are effectively stripped from the water. The clean water fills an underlying pipe system which captures the resulting clean water. This clean water can now be transported to a new pre-determined location.
What about additional infrastructure?
In larger systems, it is common for a Gross Pollutant Trap to be installed at the head of the biofiltration system. This allows for large deposits of sediments and particles to be trapped before entering into the biofiltration system, therefore increasing the longevity of the system. Biofiltration systems are designed to be excavated and replanted approximately every ten (10) years.
What is the City doing?
The City has recently completed the construction of a biofiltration system (also known as a treatment train) at Hyde Park as a part of the Hyde Park Lakes Restoration Project. This biofiltration system assists in treating the storm water from the Hyde Park Catchment before it is released into the lakes to assist in keeping the lakes full. This system is approximately 850m2 and is located on the North West side of the stage off Vincent Street.
For further information on the Hyde Park Lakes Restoration Project click here.
For further enquiries regarding biofiltration, please contact the City's Project Officer - Parks & Environment, Sarah Hill, on 9273 6000 or by email at sarah.hill@vincent.wa.gov.au.
