Challenge

Australia's Eraring Power Station, owned by Eraring Energy, needed to treat secondary sewage from the nearby Dora Creek municipal wastewater plant for recycle as high-quality boiler feedwater.  The power plant was sharing potable water with 25,000 homes, resulting in an intermittent supply.  Secondary sewage needed to be piped 10 miles (17 kilometers) to a sea outfall.

Solution

Siemens Water Technologies provided Eraring with a microfiltration and reverse osmosis (RO) system to treat secondary sewage and recycle the treated water to an existing deionizer. Eraring Energy saw microfiltration/RO technology as a benchmark for treating and recycling secondary sewage, and a way to substantially reduce annual potable water and demineralized water production costs.  Siemens also provides service on the equipment under a service contract

• Started up in February 1995, the microfiltration/RO system is producing high-quality boiler feedwater and has turned the power station into a zero discharge operation. 
• Total cost savings to the company at the end of 2002/03 were almost $3.7 million (US), with the largest cost savings in water charges and downstream ion exchange regeneration chemical costs. 
• Overall, the total chemical costs for both microfiltration and RO units are just over $.01 (US) per 1,000 gallons of reclaimed water produced.  Annual savings in the station's demineralizing plant are estimated at $52,000.00 (US).
• The microfiltration and RO systems at Eraring still contain some of the original installed membranes, making this the longest operation of membranes in an effluent reuse application in the world.
• Despite the varied age of the membranes, the reclaimed water produced contains far fewer impurities than the previously used potable water.