From Australia’s water-logged east it is interesting to see that Perth, after one of its driest years on record in their ongoing drought, is running a $50 million recycling water trial, which could mean Perth will be drinking recycled water by 2015.
WA’s Water Corporation will investigate passing waste water normally flushed out to sea through a three-stage treatment process before pumping it 120m to 220m underground to be further filtered. After this the water will be stored and monitored to determine whether it is drinkable.
This process could eventually supply 35 megalitres of water, or more than 10 per cent of Perth’s needs.
Orange County, in the US, has safely used recycled water stored underground for more than 30 years.
It is acknowledged that overcoming community opposition to drinking treated sewage could be a very big challenge. Some years ago the Queensland state government met fierce opposition after announcing treated waste water would be pumped straight into southeastern dams if they fell below 40 per cent.
What Nick Turner from the WA Water Corporation says about this reaction:
“It’s a good example of what not to do…they hurried. They had to hurry. They were in a position where they didn’t have a choice about going slowly and bringing the community on board…
A key point about this that we emphasise is that this is putting water in the bank every day.
Last year, we had the best (rain) year in 10 years; this year, we had the worst year ever. What this allows you to do is store the water in the aquifer.”
The treatment process involves subjecting the water to ‘ultrafiltration’, reverse osmosis, which is used in desalination, and then ultra-violet light, as a final disinfectant.
Nick says this would remove chemicals, bacteria, viruses and other micro-organisms to World Health Organisation standards. The water would also need state Department of Health approval for drinking.
ANU Professor of infectious diseases, Peter Collignon, warns that sewage contains very high levels of viruses and drugs and should be used for drinking only as a last resort.
He says bugs had infected the water in Queensland at least twice and it was clear the treatment process was not foolproof.
“Things do go wrong at times..
The testing that seems to be in place for this would not detect, necessarily, a failure in the system. It’s not as if viruses never got through the whole system, because the reports show occasionally they do, even though they were never supposed to.”
Nick Turner is confident the system will work saying:
“The water is checked all the way through that system and the treatment system itself is checked online 24/7.”
The trial will run until the end of 2012, when recommendations will be made to government. A full-scale treatment plant for up to 140,000 homes could be operational as early as 2015.
QUEENSLAND’S WESTERN CORRIDOR RECYCLED WATER PROJECT
This $2.5 billion Western Corridor Recycled Water Project is the largest recycled water scheme in Australia and can provide up to 232 megalitres per day of purified recycled water. It is the third largest advanced water treatment project in the world. Almost all of Brisbane and Ipswich’s treated wastewater is used for this project.
The project has reduced the demand on Wivenhoe Dam water supplies and extended the long-term water supply capacity of the South East Queensland region. Similar processes have been used to provide drinking water in Singapore and in Orange County, California.
DEFINITIONS FROM THE WATER SECURE WEBSITE
What is recycled water?
Stormwater, greywater, rainwater and treated wastewater are all alternative water supplies that, when treated as required, are suitable for a range of purposes. This can include irrigating grazing land and crops, horticulture, industrial processing, residential dual pipe schemes, and to keep our public parks and gardens green.
What is purified water?
After wastewater is processed at secondary treatment plants it can be purified to the highest standard. New advanced water purification plants can remove minerals, nutrients, organic matter and bacteria. The highest grade of water – even purer than drinking water – can be produced using technologies of microfiltration, reverse osmosis and ultraviolet light. It can be used for kidney dialysis and industrial processes such as pharmaceutical or boiler feed water. Purified water is so clean and safe that, if needed, it can be blended with reservoir water to increase our drinking water supply.
What is desalinated water?
Desalination is a technology that separates dissolved salts and other minerals from seawater or other salty water to provide clean drinking water. Modern desalination plants use a process called reverse osmosis, which involves the removal of salts and other minerals out of the water as it moves through a membrane process (moving through many thin sheets of material) under high pressure. Desalinated water is often used to supplement drinking water supplies in many countries, including some Australian cities and towns.
RECYCLED, PURIFIED AND DESALINATED WATER CURRENTLY IN USE
Recycled water is already being used in the irrigation of agriculture, parklands and golf courses.
Purified water is being used in South East Queensland by Tarong and Swanbank power stations, and there are a large number of potential agricultural and industrial users. Current state government policy is for purified water to be added to Wivenhoe Dam should the region’s combined dam water level fall below 40 per cent.
Many areas of the Gold Coast and Brisbane receive a blend of dam and desalinated water, however daily supply (production) and demand will result in blend variations throughout different areas of the water supply network.
IS PURIFIED RECYCLED AND DESALINATED WATER SAFE TO DRINK?
Yes. Purified recycled water and desalinated water is clear and odourless. Both purified recycled water and desalinated water undergo high standards of treatment to ensure they are safe and meet the requirements of the Australian Drinking Water Guidelines and will continue to do so as desalinated water is added to the water grid.
NATIONAL GUIDELINES FROM PEAK HEALTH BODIES
Queensland Health has developed health-based water quality criteria for purified water, based on national guidelines and recommendations from peak health bodies such as the World Health Organisation and the National Health and Medical Research Council.
Can we beat the ‘yuk’ factor I wonder?