RESEARCH & EVENTS
Desalinating groundwater : Is it feasible during dry conditions ?
A NEW project is underway that will examine the opportunities and risks associated with identifying , sourcing and treating brackish groundwater . Brackish water is broadly defined as having a salinity between freshwater and saltwater . The One Basin Cooperative Research Centre project is investigating whether it is viable to desalinate this water to help the agriculture sector in the Murray Darling Basin be more resilient , especially when allocations from the river system may be limited because of drought and a changing climate . “ Previous studies by the CSIRO have estimated the volume of sustainable brackish groundwater in the Murray Darling Basin is more than 2000 gigalitres per year and this could be a potential resource for growers ,” said Michael Leonard from the University of Adelaide and project team member . Globally less than two per cent of desalinated water is used in agriculture . A demonstration site has been established at Century Orchards , east of Loxton , where 700 hectares of almonds and 100 hectares of pistachios are planted . Century Orchards ’ Technical Manager Gemma Nunn said while groundwater won ’ t be the solution for expansive hectares of permanent plantings during dry times , it might be a good supplementary water source . Ms Nunn said as part of the project a control area will be irrigated from the Murray River , another three rows will get a 50-50 mix of river and desalinated water and the final three rows in the trial will be 100 per cent desalinated water . There are three aquifers in the Loxton / Berri area . The groundwater is being extracted from the confined aquifer ( the Murray Group Limestone ), via a bore that ’ s 130m deep . This bore was sunk by Century Orchards back in 2022 . The Osmoflo reverse osmosis system being used in the demonstration can produce 2.9 kilolitres of fresh water an hour , which equates to almost 70
The One Basin Cooperative Research Centre is investgating whether it ' s viable to desalinate brackish groundwater to assist supply for agriculture , especially at times of low water allocations .
kilolitres per day , if run for a full 24 hours . For every 2.9 kilolitres of fresh water that is produced , seven kilolitres of brine is generated . One Basin CRC Loxton Hub Manager Kym Walton said larger reverse osmosis systems are available . “ This project is designed to prove that brackish groundwater could be a valuable supplementary water source for agricultural use ,” he said . The brine created during the reverse osmosis process will be pumped back into the top aquifer ( the Loxton / Pliocene Sands ). A well construction permit and a licence to drain or discharge water into a well were obtained from the Department for Environment and Water before the two discharge points were drilled . The two aquifers are separated by a layer of clay , avoiding adverse environmental effects like salt mobilisation or a reduction in water quality . When the water is extracted from the confined aquafer it is 12,500 EC . The brine being put back underground is 17,600 EC , but it ’ s being placed in the upper aquafer which is already 20,000 EC .
Most Australian desalination projects are large and use seawater to boost dwindling drinking water supplies in coastal cities . The brine produced from these plants is discharged into the ocean . In the Murray Darling Basin , salt interception schemes use evaporation basins to intercept saline groundwater to prevent it entering the river . “ Managing desalination brine via aquifer discharge has the potential to lower some of the costs associated with brackish groundwater desalination , increasing its cost competitiveness with other water sources ,” Mr Leonard said . As part of this project , an online resource and cost calculator will be produced to support cost benefit analyses of desalination for agricultural purposes . The plant commenced operation in August . The first site visit is taking place on Thursday 26 September . To register for this event , click here . To find out more about the project , visit the website and subscribe to the newsletter .
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