Veolia Water is the Scheme Operator of Queensland's Western Corridor Recycled Water Project. This is the southern hemisphere's largest advanced recycled water project with the capability to provide 232 million litres of purified recycled water each day. The project treats wastewater to create purified recycled water for reuse in industry and for return to the Wivenhoe Dam, the main drinking reservoir for south-east Queensland, if required in the future.
Q. How is the water treated at Western Corridor?
A. There are seven stages of treatment to create safe drinking water . Three of these stages are contained within the Western Corridor's advanced treatment plants, operated by Veolia Water. The advanced water treatment plants process the wastewater through microfiltration, reverse osmosis and advanced oxidation to remove viruses, bacteria and chemicals. At this point, the water is ready for reuse by industry.
Q. How many chemicals are found in this wastewater being treated?
A. Many of these are not found at all and those that are, are at a very low level. The treatment processes ensure they are removed.
Q. Is further treatment needed to make this water safe for drinking?
A. Yes. Two further treatment stages are required to create drinking water. This includes blending the purified recycled water with the natural water in Wivenhoe Dam and exposing it to sunlight followed by the usual treatment of water at a water treatment plant before it enters the drinking water distribution network.
Q. How 'clean' is recycled water?
A. Recycled water from the Western Corridor Project is treated to drinking water standards that are even more stringent than the Australian Drinking Water Guidelines. The Western Corridor's recycled water must meet Queensland's Public Health Regulation which includes both the parameters set out by the Australian Drinking Water Guidelines and a range of additional parameters.
As this is a regulation, and not just a guideline, we must meet these requirements every time.
Q. Who sets this level of compliance?
A. It has been set by toxicology, water quality and health experts.
Q. How else do you ensure high water quality?
A. Water samples from the Western Corridor Project are also tested by an external laboratory for the presence of over 400 chemicals, viruses and bacteria. All water samples tested to date during construction and operations have met the Australian Drinking Water Guidelines and Queensland's Public Health Regulation.
Q. What do water quality tests actually test for and who reviews the results?
A. Water quality tests check for specific viruses, bacteria and a vast number of different chemicals including pharmaceuticals. Results are reported to the Office of Water Supply Regulator and reviewed by the Queensland Department of Health.
Each water treatment plant must demonstrate three months of intensive water quality testing (180 parameters twice a week) prior to being allowed to deliver water to the Wivenhoe Dam, which will be required if the combined dam levels drop below 40 per cent.
Q. What if there are problems in the treatment processes caused by human error?
A. The advanced water treatment plants are fully automated with extensive monitoring and control equipment. If there is an early indication of a problem at any of the treatment barriers, the automated systems stop the process so operators can correct problems before water quality is affected. Purified recycled water also sits in the dam for more than six months, mixing with reservoir water and being exposed to sunlight. The dam water also has to go through the water treatment process before it is drinkable.
Q. Is purified recycled water safe to drink?
A. Yes. The purified recycled is the highest class of recycled water and must meet even more stringent standards than desalinated water or rainwater, before it can enter drinking water supplies.