MD desalination pilot successfully used with waste heat

Results from an Australian trial to demonstrate the potential for a membrane distillation (MD) process to use waste heat from heavy industry to desalinate saline effluent have shown the system can produce high-quality water at temperatures as low as 30°C without an increase in greenhouse-gas emissions.

A team from Victoria University’s Institute for Sustainability & Innovation operated a 240 L/d pilot plant over three months at the end of 2011 using waste heat from Ecogen Energy’s 500 MW Newport Power Station. The trial was carried out in partnership with City West Water (Melbourne), GWMWater and Water Quality Research Australia.

The pilot plant treated effluent from an ion-exchange demineralisation plant of approximately 3,000 mg/L TDS. The trial showed that permeate flux was relatively consistent up to reject concentrations of 62,300 mg/L, after which flux decline was observed.

The maximum water recovery achieved in the final phase of the trial was 92.8% with a reject concentration of 71,400 mg/L and salt rejection of 99.97%. The experiment successfully tested the MD process’ longevity and robustness, demonstrating a system driven by waste heat at input temperatures as low as 30°C, which achieved permeate flux of 3-4 L/hr/m², of highly desalinated water.

A paper on the findings is being prepared for presentation at the Australian Water Association’s OzWater ’12 conference in May 2012.