Innovative aeration device for removing carbon dioxide from bore water
Annual Conference
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Mosgiel's bores-sourced water supply has high levels of free carbon dioxide which is corrosive to metallic plumbing. Formerly treated by limited aeration and caustic soda dosing, alternatives to the caustic soda dosing were considered following three unrelated overdosing incidents. Options considered included aeration (at individual plants and at a single location) and full chemical dosing. Upgrade of the existing plants was severely limited by their location in residential areas and their very constrained site areas.
A vortex accelerator device manufactured in USA had great potential for Mosgiel. Although having a lower gas removal efficiency than aspirating type aerators the device required significantly less energy to operate and final carbon dioxide removal could be achieved by using the existing facilities to dose soda ash. Two of the devices within the existing aeration chamber would remove the bulk of the carbon dioxide. This met the noise and site area constraints and was the lowest cost option by a significant margin. Plant modifications have been completed and the system meets the project objectives.
Only two sizes of vortex accelerators are presently manufactured. The operating ranges and guidance on installation from experience gained during this project are covered in the paper.