Keeping urban waterways clean

View story in H20 Thinking

New studies are sharpening our choice of plants and soils for use in biofiltering urban stormwater.

‘Biofiltration’, as it is called, uses natural materials — plants and soil — to remove particulates, nutrients and heavy metals from, and slow down, stormwater that otherwise would surge off urban surfaces and into creeks and other waters, lowering their quality.

It is accepted wisdom that water filtered through sand beds can be clean enough for human consumption. But now data are being gathered on the detail of how this type of system works.

Researchers at the Facility for Advanced Water Biofiltration (FAWB) at Monash University in Melbourne have been finding answers to questions such as these: What percentage of suspended solids is removed in biofilters? How far must water travel through a biofilter to guarantee capture of nutrients dissolved in it? What plant species contribute best to a biofiltration bed? How can clogging and compaction be avoided in biofilters?

Research manager at FAWB, Professor Ana Deletic, says: “Our research has shown that biofiltration is flexible in terms of size, location, configuration and appearance. Biofilters can take the form of vegetated roadside strips or rain-gardens within parks or public space. They are fairly robust, though our work has challenged the concept that biofilters simply need to be vegetated to be effective.”

eWater’s urban software music version 4 includes bioretention and infiltration modules developed in collaboration with FAWB, and music will continue to incorporate the latest in biofiltration science.

Professor Deletic says: “Based on the results of our research, biofiltration can be trusted as an effective and reliable urban stormwater treatment technology”.