Leachate management has long been a significant challenge at the Shoal Bay Waste Management Facility, particularly due to legacy landfill sites and Darwin’s high-rainfall climate. Leachate is a toxic liquid produced in landfills that can contain heavy metals, excess nutrients, and persistent chemicals such as PFAS (per- and polyfluoroalkyl substances), which are especially difficult to remove.

While current technology can effectively treat nutrients and heavy metals, PFAS removal remains complex, often requiring a combination of advanced methods.

To address this, City of Darwin partnered with Water Carbon Group (WCG) to trial a chemical-free PFAS removal solution. After a successful pilot, WCG was awarded a contract to design, build, and operate an innovative leachate treatment plant, the first of its kind in Australia.

This landmark project sets a new benchmark in sustainable waste management and environmental protection.

Solution

The Leachate Treatment Plant uses a world first innovation called Low-Energy Evaporative Fractionation (LEEF) system to remove PFAS from leachate. The air bubbles injected in the raw leachate column allows PFAS to attach to the air bubbles and be skimmed from the water as a foam without the need for chemicals and with minimal energy.

Treated effluent from the LEEF System® is then further processed via a biological treatment plant which utilises microbes for nutrient removal. Finally, the treated leachate is used to irrigate a vetiver grass crop where the Vetiver plants draw up the leachate and residual contaminants, resulting in a zero-discharge treatment plant.

Outcomes

• This sustainable, cutting-edge leachate treatment solution has supported City of Darwin to further protect the environment from toxic leachate.
• The leachate treatment system at Shoal Bay is the first in the world treating PFAS in leachate coupled with biological and ecological treatment.
• The plant uses zero chemicals, processing up to 140,000 litres of leachate a day. 
• The development of the LEEF System® through an intellectual property agreement is an outstanding example of how Local Government and the private sector can partner to solve emerging environmental challenges.