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Managing biosolids

Beneficial use strategy

Melbourne Water’s strategy for the beneficial use of biosolids was revised during the year due to targets not being met in recent years. The strategy was developed in 2002 and focused on using Eastern Treatment Plant biosolids in soil blends, using Western Treatment Plant biosolids as a fuel and remediating the remaining stockpiles at the Western Treatment Plant over the long term.

However, the non-typical properties of the biosolids, a lower than forecast demand for biosolids by soil blenders and higher than anticipated costs for reuse have constrained opportunities for further use. For biosolids produced in future at the treatment plants, the revised strategy recommends further research and investigation of the potential for land application, using the clay-rich biosolids stored at the Eastern Treatment Plant for construction fill in civil engineering projects such as freeways, and continuing to develop the concept for using the stored biosolids at the Western Treatment Plant, which are contaminated with heavy metals, for energy recovery. Research into options for remediation of Western Treatment Plant biosolids is continuing.

During the year, Melbourne Water began working with EPA Victoria to develop guidelines for the environmental management of biosolids used as a construction fill, and a feasibility study began on the potential for energy recovery from the biosolids stored at the Western Treatment Plant.

Assisting other water authorities

Melbourne Water continued working with Barwon Water on the management of its biosolids, which are being stored and dried at the Western Treatment Plant (for subsequent beneficial use) until a permanent biosolids processing facility is completed at Barwon Water’s Black Rock Treatment Plant in 2009.

The Eastern Treatment Plant accepted a second and final transfer of biosolids from South East Water’s nearby wastewater treatment plant at Cranbourne. This helped South East Water decommission the site, where land was rezoned residential.