Solar powered desalination

Leader

 

Challenge

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.

Investigation

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.

Outcomes

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.

Future Direction

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.

Partners

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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

Related Project: Developing highly conductive graphene electrodes for capacitive desalination (Phase 1 and Phase 2)

Further Information

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