Teacher background information
There are different types of desalination. The main processes are evaporative (thermal) desalination, which is used in this experiment and reverse osmosis (pressure) desalination, which is used in the Perth Seawater Desalination Plant and Southern Seawater Desalination Plant.
Perth Seawater Desalination Plant
In response to our drying climate, Water Corporation built a seawater desalination plant on the coast near Kwinana in 2006. This has now become an important part of the Integrated Water Supply Scheme. The plant treats water from the ocean to produce freshwater to supplement our existing water supply. The by-product of the treatment process (a salty concentrate) is returned to the ocean. Safeguards have been put in place to make sure that the environment is not adversely affected by the plant’s discharge into Cockburn Sound.
Energy for the plant is purchased from the Emu Downs Wind Farm. Reverse osmosis technology was chosen for Perth’s desalination plant because it is the most economical and environmentally friendly process.
The reverse osmosis process uses high pressure and a very fine membrane to extract fresh water from salty water. The membrane acts like a strainer, allowing water molecules to pass through and retaining salt and other impurities. Small desalination plants on fishing boats, yachts and large cruise ships and in some households use reverse osmosis and the process has been used for many years to provide fresh drinking water to the remote towns of Denham and Ravensthorpe.
Southern Seawater Desalination Plant
Located in Binningup in the South West, this plant is capable of producing 100 billion litres of drinking water a year – that’s 1/3 of Perth’s water supply!
The plant’s energy requirements are offset by the entire output from 2 renewable energy farms near Geraldton. Water Corporation purchase 100% of the output from these renewable energy sources.
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Did you know?
The Perth Seawater Desalination Plant, located in Kwinana, was Australia’s first large-scale seawater desalination plant.