@squarepantsAgreed, this is (basically) salt encapsulation,...

@squarepants

Agreed, this is (basically) salt encapsulation, although there is certainly more to it in terms of the crystalization of the brines, siting and design of the landfill and the ongoing monitoring.

QLD CSG operations are highly regulated. One aspect of this regulatory framework is overseen by the Queensland Department of Environment and Science (QLD DES) which covers water management and waste disposal.

https://environment.des.qld.gov.au/management/activities/non-mining/water/csg-water#approving_the_disposal_of_csg

Very simply, QLD DES has banned the use of evaporation ponds for CSG wastewater. Currently saline waste (brine), the waste after treatment of csg water by filtration, reverse osmosis and ion exchange, is being stored temporarily in regulated structures (dams). However this is a relatively short term measure until a long term management approach is adopted.

The CSG Water Management Policy 2012 requires the saline waste to be management in accordance with these two priorities:



The industry's preferred method of disposal (and one supported by the UQ report, based in info back in 2020) was salt encapsulation. However the UQ report also recommended the industry continue to invest in research that will "c. investigate any emerging technologies that are identified through their own efforts or in future reviews"

Since this report, PWN developed the integrated iBC-aMES technology solution and completed the recent feasibility study for a major CSG operator with positive results ( per recent announcements).

University of Queensland(Centre for Natural Gas) February 2020 - Independentreview: Brine and salt management (Section 6, Queensland Gas: end-to-end wateruse, supply and management) (UQ Report)


At the moment no such encapsulation facility has been built nor approved by the DES, as far as I am aware.

"While encapsulation of salt has been identified as the most viable long-term solution, salt encapsulation facilities are not currently used by the industry," the DES spokesperson said.

"A spokesperson for the Queensland Department of Environment and Science (DES) said it continued to work with the industry, landholders, and environmental groups on a plan for the long-term storage of waste CSG salt."
https://www.abc.net.au/news/rural/2022-04-26/queensland-coal-seam-gas-industry-big-salt-problem/100990978

I think, there are certainly some issues with salt encapsulation not least the long term management and monitoring of the disposal site and the associated costs, and the long-term risks of failure of primary/secondary containment of the waste and at the end of the day there is no real end solution. As identified in the abc report above.