ISI harnesses waste heat for desalination

A three-month trial conducted by scientists from Victoria University's Institute for Sustainability and Innovation (ISI) has demonstrated that waste heat can be harnessed to power wastewater desalination.

The trial, conducted at Ecogen Energy’s gas-fired Newport Power Station, proved that the ISI system used 50% less energy than traditional techniques to desalinate water. After further refining the system, the scientists achieved a 95% reduction in electricity use.

ISI’s membrane distillation technology uses waste heat to evaporate wastewater through a fine membrane. The evaporated water is condensed on the membrane, emerging on the other side at above tap water standard. It is then re-used around the plant.

“As energy and water become increasingly scarce, this technology is a major development,” said project leader Associate Professor Mike Duke. “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.”

According to Professor Duke, many factories already produce enough heat to use this technology, but few harness it. Compared with conventional evaporative desalination systems, which require heat of 70°C or higher, ISI’s system can use waste heat as low as 30°C.

“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,” Professor Duke 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.

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

The project was supported by the Smart Water Fund and led by Water Quality Research Australia and Victoria University’s Institute for Sustainability and Innovation.