What happens to the Collected Salt?

The two basic methods of disposal of saline waters from these schemes are through concentration and seepage back into the groundwater or by crystallising of salt on the ground surface.

Groundwater Disposal The saline water is concentrated through solar evaporation and the resultant solution is permitted to seep back into the groundwater. Although this disposal method is only employed in areas where there would be minimal impacts, it does however eventually flow back to the river, but at a very slow pace.

Crystallisation

In some selected disposal basins, the water is evaporated, leaving the crystallised salt on the surface. In a number of areas, commercial operators havrvest this salt for resale. Different salts are extracted at different stages for different uses:

• calcium salts - used for gypsum
• sodium chloride - used for tavle salt, agriculture, swimming pools, the tanning industry and as a de-icing agent
• bitterns - a mixture of magnesium, chloride, calcium and sodium left over from the above two extractions, used for dust suppression (for example, on dirt roads)
• magnesium sulphate extracted from the bitterns - used as a fertiliser, although much more expensive to extract than other salts, it has a high value as well.

Salt harvesting is carried out by a number of small commercial 'boutique' operators. It is never expected to be a large industry along the River Murray.

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All photographs © 2003 Phil Pfeiffer