Industrial waste can power desalination

Victoria University scientists have shown the viability of a new desalination technology that uses almost no electricity and has the potential to save huge amounts of water.

Project leader Associate Professor Mike Duke said a three-month power station trial in Newport proved desalination of wastewater - which usually relies on electricity - could instead be powered by an industry’s own waste heat.

The membrane distillation technology uses waste heat to evaporate wastewater through a fine membrane, Associate Professor Duke explained. The evaporated water condenses on the other side of the membrane as treated water - at above tap water standard - for re-use around the plant.

The trial conducted at Ecogen Energy’s intermittent operating gas-fired Newport Power Station showed the system used 50% less electricity to desalinate water than traditional techniques. An updated design was then shown to use 95% less electricity.

“It has now been proven to work and as energy and water become increasingly scarce this technology is a major development,” he said. “If it were scaled up to a continuously operating industry of similar size to Newport Power Station, it could desalinate around 7 million litres of water per day, which is the equivalent of supplying fresh water to about 25,000 people in Melbourne.”

Associate Professor Duke said many factories and industrial settings produced enough waste heat for this system to operate, but that currently that heat was not being harnessed.

“One of the most exciting outcomes of our tests is that our system can use waste heat as low as 30°C,” he said.

Conventional evaporative desalination systems use 70°C or higher.

“We have seen several industrial cases where there is far more waste heat available than what is needed to treat the entire site’s wastewater currently going to the sewer,” he said. “There are a lot of industries that are keenly watching this technology and we are already in consultation with the mining, manufacturing and dairy industries as well as water utilities to move to larger pilot trials.”

The technology is relevant to many industries as saline effluent resulting from industrial processes is a common trade waste issue businesses must manage, both internally and in negotiation with water authorities.

“Membrane distillation technology is just emerging globally, so our demonstration on an industry site puts us at the forefront of its international progress,” Associate Professor Duke said.

The project was supported by the Smart Water Fund and led by Water Quality Research Australia Ltd and Victoria University’s Institute for Sustainability and Innovation, with support from City West Water, GWM Water and Integrated Elements. It was funded for $97,500 by the Smart Water Fund, Water Quality Research Australia and City West Water.