For inland communities in Australia the only reliable water resource is groundwater and limited surface water but much of this contains salt in concentrations higher than what is acceptable in drinking water guidelines. There is huge demand for small decentralised desalination plants in these regions for communities, mining, agricultural and health services. Membrane-based reverse osmosis systems require technical maintenance and suffer from severe scaling and fouling, depending on the quality of the source water. For example, the high levels of reactive silica and ferric ions in the groundwater in Northern Territory make the operation of high pressure membrane systems difficult if not impossible.
Capacitive deionisation (CDI) desalination is an attractive, environmentally‐friendly technology which has relatively low energy demand and doesn’t produce any secondary chemical wastes. This process also doesn’t require pressure driven membranes or high pressure pumps which aid in avoiding scaling issues. The operation of CDI requires DC power and can be coupled with renewable energy sources, such as solar photovoltaic and battery banks.
A portable CDI unit was field tested in Wilora, a remote community in Northern Territory, and in Mawson Lakes, an urban area in South Australia. The Wilora water has high silica content and the Mawson Lakes water has a high level of dissolved organics. Determine performance under these conditions and develop effective cleaning protocols.
Despite local ground water containing high level of dissolved silica, the CDI unit adsorbed limited amounts with no scaling detected. Calcium and magnesium scaling occurred but had little effect on long-term performance. There was a noticeable reduction in performance removal when organic fouling occurred but performance could be fully restored by cleaning with a mild solution (0.01 M citric acid for calcium and magnesium scaling and 0.01 M sodium hydroxide for the organics fouling).
The CDI unit demonstrated effective brackish water treatment and was operated by a 4kW photovoltaic panel. Compared with the required maintenance of a reverse osmosis treatment plant, the portable CDI unit offers an easy and viable alternative solution to brackish water treatment especially in remote area communities.
It is feasible to apply CDI technology to the treatment of brackish groundwater in remote areas and should be considered as a viable option for communities requiring drinking water supplies.
Total Value: $560,274 (cash and in-kind contributions)
Principal Investigator: Professor Linda Zou
Title: Application of capacitive deionisation in inland brackish water desalination
Length: 28 months
Personnel: 4 collaborators contributing 2.2 FTE
- 2014. NCEDA Fresh Ideas Exchange. Perth, Australia.
- 2013. Mossad, M. Evaluation of capacitive deionisation for inland brackish groundwater desalination. PhD thesis, University of South Australia.
- 2013. International Desalination Association World Congress. Tianjin, China.
- 2013. OzWater Australia’s National Water Conference and Exhibition. Perth, Australia.
- 2013. Zhang, W., et al. A study of the long-term operation of capacitive deionisation in inland brackish water desalination. Desalination 320(0): 80-85.
- 2013. Mossad, M., et al. Using capacitive deionisation for inland brackish groundwater. Desalination 308(0): 154-160.
- 2013. Mossad, M.,et al. Evaluation of the salt removal efficiency of capacitive deionisation: Kinetics, isotherms and thermodynamics. Chemical Engineering Journal 223 (0):704-713.
- 2013. Mossad, M., and L. Zou. Study of fouling and scaling in capacitive deionisation by using dissolved organic and inorganic salts. Journal of Hazardous Materials 244–245 (0):387-393.
- 2012. Australian Water Association Meeting. Adelaide, Australia.