July 1, 2010
(Project 1019) Project Leader—David Waite, UNSW
The primary objective of this investigation was to determine the extent of scale formation in remote water supplies reliant on groundwater in the NT and WA, and to review and recommend the most appropriate treatment and/or management option(s). This is an issue of some importance as areas with particularly severe
scale formation contend with excessive energy consumption, as scale affects heating elements, and also must frequently replace domestic fixtures such as clogged taps and shower heads. This project assessed the calcium, magnesium and silica-based scale formation potential in bores managed by Northern Territory Power and Water Corporation (PWC) and the Western Australian Water Corporation (Water Corp).
From the data sets obtained it was shown that the problem of scale formation within the NT and WA is theoretically widespread. The University of New South
Wales devised a calculator to determine the theoretical potential of different groundwaters to form scale, based on specific water quality parameters. The scale
calculator provides the saturation index of a range of minerals, including calcium carbonate, able to form a scale, or likely to be of concern for the treatment of hard
groundwaters. The effect of temperature on the formation of scale, in particular the increased potential for carbonatebased scale to form at higher temperatures, is built into the functionality of the scale calculator.
Following a thorough review of possible treatment options, measures for preventing scale formation are summarised. Options reviewed include highly
sophisticated desalination technologies; such as reverse osmosis, nanofiltration, capacitive deionisation and electrodialysis reversal; in addition to lower technology desalination options, such as solar thermal desalination and deionisation resins. The following low cost treatment alternatives, which prevent scale
formation by means other than desalination, were also investigated: pH adjustment, ion exchange, chemical antiscalant addition and dilution of the source water with rainwater. Depending on the size of the community and its water requirements, the different options assessed vary in their effectiveness, in particular set-up
costs and ongoing operations and maintenance. These are discussed in detail in the project final report.
The final report will be available on the WQRA Members Only area of the website shortly. The project team includes Adele Jones and Professor David Waite, with industry input from CAT, PWC and Water Corp. 2010 Summer Student Glen McMellon, who won this yearâ€Ÿs proze for best presentation, also contributed to this project.
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