Water purification systems LIVE TECH DEMO - Greg Leslie - HotHouse WATER
The University of NSW carries out world-leading research and development into water recycling and desalination technologies. The bulk of this work is done by the UNESCO Centre for Membrane Science and Technology, which specialises in the development of synthetic membranes and associated technologies and processes. Membranes are key to mechanical purification of water. Essentially a membrane is a thin and incredibly strong piece of material covered with very tiny holes. These holes are large enough to allow water molecules through them but small enough to filter out almost anything larger. This includes all the stuff that would make water look ‘dirty’, plus the really tiny nasties like bacteria, amoeba and even viruses. Modern membranes will even filter out complex molecular pollutants typically found in wastewater, like ethanol estradiol (from birth control pills) and paracetamol.
To get water to pass through such fine membranes requires it to be highly pressurised, which calls for a lot of energy, especially for salt water. The desalination plant currently installed at Kurnell in Sydney, like most built in the past decade, uses a membrane-based technology called reverse osmosis. It has been said that desalination plants are essentially a way of converting water demand into energy demand, which carries its own issues in a world where reduction of power consumption and decarbonisation of our energy system are the highest priorities for society. The same reverse osmosis membrane technology is used to treat waste water (such as the Flow Systems installation at Central Park) and due to the lack of salinity the energy requirement is a fraction of that needed for desalination - between 3 and 30 times less, depending on the quality of the input. Then there is a conversation about giant centralised facilities versus thousands of smaller decentralised systems. As our cities become more water constrained, controversial technologies like desalination are being weighed up against more systemic approaches to water recycling and reuse. With new desalination technologies in the pipeline, including the promise of graphene based membranes that could reduce energy (and dollar) requirements by 99%, what is the future for desalination and water recycling in Australian cities, and at what scale?
We were joined at HotHouse by Greg Leslie and colleagues from the UNESCO Centre for Membrane Science and Technology, who treated us to a live demonstration of their mobile reverse osmosis machine.