A solar-powered desalination plant for Brisbane’s Mt Coot-tha Botanical Gardens is believed to be the first in Australia and a model for similar irrigation systems in Queensland parks and nurseries.
The system uses two self-positioning solar panels and is estimated to cost around $400,000. Commissioned on Monday, it produces 32,000 litres a day for irrigation, which is around 25 per cent of the Gardens’ needs.
The Brisbane desalination plant uses solar power during the day and mains grid power at night.
The scheme draws brackish water from the Great Artesian Basin, 80 metres beneath the Botanical Gardens in Brisbane.
Water straight from the bore is too salty to immediately use on the gardens. However, when the bore water is mixed with water in the six lakes of the Botanical Gardens site, it can then be used to irrigate the 60-hectare site.
The salt water “by-product” from the solar powered desalination process will be pumped through marine beds of salt-loving plants that are yet to be planted at the gardens, to complete the recycling process.
Associated with this project, a 20 million-litre dam will be built near the Gardens when the Northern Link tunnel is built. This water will also be fed into the Gardens’ irrigation water supplies.
Lord Mayor of Brisbane, Campbell Newman, said the results from the first week of operations were promising.
“Back during the difficult times over the past two or three years we did a lot of drilling around the city for our aquifer project and we discovered water on the site not far from where we are standing now,” he explained.
Tests discovered the salt content of the water too high, so a trial solar powered desalination plant project was set up between University of Queensland and Victoria University, with money contributed from the State Government ($150,000) as well as Brisbane City Council ($100,000).
“I think this is a very good, elegant solution and case study as well that can be used buy other councils and botanical gardens around Australia,” he said.
“We think it is a first in terms of using the water in this particular way.”
Mt Coot-tha Botanical Gardens has been off the water grid for the past two years, using water it has collected on site, although it has 300,000 litres of water delivered each week.
The Botanical Gardens uses about one million litres of water a week, or 50 million litres each year. The Brisbane desalination plant would be the first of its kind.