A committee set up by the Victoria state government in Australia has recommended that enforceable water recyling and reuse targets at Melbourne’s sewage treatment plants should be raised to 50% by 2012 and 70% by 2015.
It also recommends a moratorium on new groundwater extraction, including groundwater for desalination.
The committee, set up in September 2007, has investigated the relative merits of supplementing Melbourne’s water supply through water efficiency and conservation, stormwater harvesting, wastewater reuse, groundwater supplies, small locally based desalination plants and other potential sources.
Approximately 62 million m³ or 23% of sewage inflows were reclaimed from Melbourne’s two treatment plants in 2007-08. The water was used directly at the plants for process systems or by external customers for irrigating agricultural areas or sporting grounds.
An upgrade of the Eastern Treatment Plant is expected to yield an additional 110-130 million m³ of Class A (tertiary treated) water from 2012.
The committee also investigated the merits of supplementing Melbourne’s water supply with water from small (110-180,000 m³/year) locally based desalination plants. It concluded that there was a limited role for such plants in Melbourne. The Commonwealth Scientific & Industrial Research Organisation advised the committee that the disposal of the brine effluent in Port Phillip Bay was the main constraint.
The committee also recommended that the contract for the 150 million m³/year Wonthaggi desalination plant should be designed to allow the volume of water the plant supplies to be varied, so as not to provide disincentives for water conservation and the development of other water supplies – including stormwater harvesting and recycling – for Melbourne.
The Victorian Government was also recommended to initiate further targeted investigations of suitable sites for aquifer storage and recovery, and if possible, establish further demonstration and trial projects.
The report can be viewed on the Victoria government website.