Stormwater treatment system combines filter media

Consulting company GHD has successfully implemented an innovative multibarrier stormwater treatment system, named the StormDMT, for a major mining company at the Port of Townsville in Queensland. The patented technology economically filters stormwater and is effective for a broad range of contaminants, including oil, grease, soluble nutrients and heavy metals.

The idea for the technology came from Kostas Athanasiadis, business development leader - Industrial Water & Coal Seam Gas in GHD’s Brisbane office. Athanasiadis said there is a “strong demand for solutions that are cost-effective and efficient at removing stormwater contaminants such as nitrogen, phosphorous and heavy metals”.

“However,” he continued, “there are few stormwater treatment technologies currently available to effectively and economically remove these contaminants, both in particulate and soluble forms, to desirable levels both here in Australia and in other key stormwater markets such as the USA.”

Athanasiadis studied the properties of different filter media as part of his PhD. He created an innovative configuration of inexpensive filter media in a cartridge that removes heavy metals and other dissolved contaminants in a cost-effective way.

GHD Commercialisation Manager - Innovations Matthew Bowler said, “Our client sought a new way to deal with stormwater runoff. With Kostas’s solution, GHD put forward an option that nobody else had considered.”

Athanasiadis said the product “incorporates a filtering system (cartridge or other types of filtering configurations) that contains a combination of the following filter media:

• Polypropylene flakes to remove oil and grease and particulate-bound contaminants;
• A zeolite named clinoptilolite to remove positive charged dissolved contaminants such as heavy metals and ammonium nitrogen. clinoptilolite has been chemically conditioned to maximise its operational ion exchange capacity;
• Laterire to remove negative charged contaminants such as phosphate, nitrate and arsenic, as well as heavy metals that have broken through the clinoptilolite layer.”

The product is easy to maintain - the filter media cartridges are designed to be replaced on-site and then recycled for re-use off-site. The system is capable of achieving low discharge levels for dissolved nutrients and heavy metals, and also has the flexibility to target contaminants specific to site requirements, meeting a range of permit licences.

Installed underground, the concept has a low-impact footprint for both retrofitting and new development applications. For a typical cartridge configuration, the system has the ability to treat flow rates ranging from 6 up to 100 L/s.

It is capable of achieving low discharge levels for dissolved nutrients and heavy metals, and also has the flexibility to target contaminants specific to site requirements, meeting a range of permit licences.

GHD carried out a trial at the client’s site, where the filter exceeded anticipated performance. The client has now adopted a site-wide solution based on the technology.