17 october 2017

Sydney, Australia

Guaranteeing drought-proof water supply

Sydney Australia

The city of Sydney is solely reliant on surrounding dams and rain for its drinking water. With Sydney’s growing population and uncertain rainfall predictions due to climate change, the New South Wales Government recognized the need for a new, non-rainfall dependent source of water to secure the city’s water supplies for the future.
The Government announced the decision to proceed with the desalination plant in February 2007 when dam levels were at 34.1% and dropping approximately 0.4% week. If dam levels had continued to decline at this rate, drinking water storage would have been 10% by July 2009, creating a risk of Sydney running out of water.
Guaranteeing water security for Sydney
Veolia Water Technologies worked with John Holland in a joint venture (Blue Water) to design and build Sydney’s Desalination Plant on behalf of Sydney Water. Veolia is now operating and maintaining the plant and intake/outlet structures under a 20 year contract.
Seawater is treated using reverse osmosis which pushes seawater through membranes where salt and any other impurities are removed, producing freshwater.
The plant has a capacity of 250,000 m3/day and provides a drought-proof water supply for 1.5 million Sydney residents. It is currently in water security mode. Care and maintenance operations will continue until dam levels fall below 70%, when the restart process will begin. The plant will then continue to produce drinking water until dam levels rise above 80%.
Meeting the highest environmental requirements
Sydney Reverse Osmosis
The energy consumption of the plant was optimized by installing a high performance energy recovery system (DWEER) on the reverse osmosis line.
The plant was built to high environmental and public health standards. Multiple safeguards protect drinking water quality and minimize the environmental impact of salty water outflows to ocean. Veolia technologies are critical to the plant’s performance—for example, by providing efficient chemical pretreatment and filtration of seawater, reverse osmosis, and water post-treatment and disinfection.
The concentrated seawater is discharged via two outlet risers each with four nozzles located approximately 300 meters out to sea in water 25 meters deep. The concentrated seawater is dispersed at about one part per thousand of background salinity within 50 to 75 meters. This minimizes the impact of brine on local ecosystems.