Desalination Plant RO Pretreatment, Australia
Country
Australia
Application
Desalination - Pre-Filtration
Water source
Seawater
Filtration solution
12 modules x 12 x 6" Galaxy
Background
Traditionally South Australia has always relied on the River Murray for about 40% of its water supply in regular years while in drought years up to 90% of the supply may come from this one finite resource. In recent years securing water supply from the River Murray is under serious threat; population growth expected over the next few decades will place even further strain on South Australia’s water supply. In recognition of these issues, on 30 June 2009, the south Australian government launched the Water for Good plan and set a goal for South Australia to become an internationally recognized “Water–sensitive State” by the year 2015. Adelaide’s desalination plant is being constructed to secure long-term and climate independent sustainable water supply for South Australia, and to reduce the State’s reliance on the River Murray and other rain-dependent sources.
Challenge
The desalination plant at Adelaide Australia is designed to supply 13,000 m³/h of desalinated water, which is about half of the hourly water demand of the city. This plant required the design and installation of a pre-treatment system with a capacity of 26,000 m³/h. The supply of water to the plant is done by a pipe that its intake point is distanced 1.5 km and in depth of 28m out in the sea. The preliminary filtration stage is done by a 3 mm coarse screen after which a Galaxy disc system with a filtration degree of 100 micron is installed. Cartridge filters and UF membranes finalize the rest of the pre-treatment stages upstream of the R.O. membranes. The emphasis on this project is as the construction contractor has defined it. Process design and technology: (From occiona Agua comprising), A membrane pre-treatment process that will provide high levels of reliability, reduced energy usage and reduced need for chemicals, Ar everse osmosis design that offers more efficient use of seawater extracted, significant energy saving and a smaller plant footprint, An innovative diffuser for the saline concentrate that will ensure adequate mixing back into the marine environment
Solution
Arkal deployed its highly effective disc filtration technology in the design and the construction processes of the preliminary filtration stage for protecting the UF membranes. The system constructed of twelve filtration modules, each comprising twelve 6” Galaxy filters with a filtration degree of 100 micron; the twelve identical modules comprise a total of 144 units of 6” Galaxy filters. The system also includes polymeric constructed manifolds so all the system components are seawater-resistant. .
Results
One of the key points of this design is energy saving; therefore all of the filters are rinsed by an external water source at a pressure of 3.5 bar. Electrically controlled pneumatic on/off valves are used as an integral part of each filtration module. Another challenge which Amiad successfully faced was the supply of a control system for preventing water hammers that may occur at opening and closing of the valves during the rinsing process. The solution incorporated was to rinse two modules in parallel causing the back-flushing pump to continuously run.
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