Western Treatment Plant Explorer : Teacher Resources : Resource 1

Resource 1

Melbourne Water and the Western Treatment Plant

The role Melbourne Water plays in providing high-quality drinking water and managing our waste is fundamental to the progress of Melbourne.

As the city grows, so do our needs as a community for high-quality fresh water. In turn, we have a growing need to increase and improve our capacity for treating sewage.

Melbourne Water is wholly owned by the Victorian Government and, in partnership with private industry, is committed to upgrading and rebuilding the infrastructure required to meet growing domestic and industrial demand (see Appendix for charter).

The Western Treatment Plant works naturally

The Western Treatment Plant is situated on the shores of Port Phillip Bay at Werribee, southwest of Melbourne. It receives and treats most of the sewage produced in Melbourne's western and northern suburbs, including most industrial wastes.

An aerial photograph of the Western Treatment Plant at Werribee.

The purpose of sewage treatment is to remove suspended solids, organic matter, nutrients and disease-causing organisms until all that remains is a liquid effluent, suitable for discharge on land, inland waterways or the ocean.

At the Western Treatment Plant this is achieved by three different natural methods of treatment - lagoon, land filtration and grass filtration. Each method produces a high quality secondary effluent that consistently meets the EPA licence requirements for discharge into Port Phillip Bay.

However, to upgrade the quality of effluent, lagoon treatment is the preferred method and, unlike land and grass filtration, can be used throughout the year. Already, over 50 percent of flow received at the plant is treated this way. It works naturally.

First, the flow is directed into a deep lagoon where solids settle. Then sewage passes slowly through a series of lagoons. At each stage, it is progressively purified as the finer suspended solids settle and micro-organisms digest the organic material. Sunlight naturally disinfects the water, while mechanical aerators speed up the natural process and help control odour.

Because enhanced lagoon treatment will significantly improve the quality of effluent, land and grass filtration methods are to be phased out and only the lagoon treatment system will be used for normal operation in the future.

Planning for the needs of a new millennium

For the Western Treatment Plant to continue to be effective well into the next century, three major factors have been addressed.

Melbourne's growing population means treatment processes must be enhanced to cope with future demands on the plant.
Odour from the system must be controlled to meet EPA standards and be kept within limits acceptable to the residents of Werribee and other local communities.
At present, the plant discharges millions of litres of treated effluent into Port Phillip Bay. However, this effluent is a precious commodity that ideally should be recycled in the interests of conservation and environment protection.

For many years now, Melbourne Water and its consultants have been investigating the options to determine which will provide the best solutions in the future.

These investigations have now resulted in a complete development strategy for the plant, one which is cost-effective and better for the environment.

The key objectives for development

To reduce the amount of nitrogen entering Port Phillip Bay.
To increase the capacity of the Western Treatment Plant.
To reduce greenhouse gas emissions and improve air quality.
To increase water recycling.

The upgrade also includes a conservation management plan to maintain and protect the wetlands and flora and fauna of the Western Treatment Plant.

Melbourne Water will continue to consult with the community to ensure all issues and concerns are addressed.

To find out more about the Western Treatment Plant visit: www.melbournewater.com.au

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