Magnetic Water Treatment to Inhibit Calcium Carbonate Scale Deposition in the Drainage System of an Old Tunnel in Seoul, South Korea

Abstract

Drainage inlets at the Namsan #3 traffic tunnel in Seoul, South Korea were found to be clogged with calcium carbonate scale deposits. Officials were concerned the clogged drains would further stress the already deteriorating traffic tunnel and wanted to see if there were any practical and economical solutions in removing or preventing scale deposits. A tunnel drainage simulator was constructed to determine the feasibility of using magnets to inhibit scale precipitation and deposition. Test results from the simulation show 6.0 and 4.4 g of deposited calcium carbonate in pipes inclined at 2° and 5° respectively, while magnetically treated water resulted in 10.8 and 4.3 g of deposited calcium carbonate in pipes inclined at 2° and 5° respectively. Calcium carbonate scale samples from the tunnel drainage test underwent x-ray diffraction analysis and showed the magnetically treated water to precipitate more aragonite. The solubility product and crystalline structures of calcite and aragonite are able to help explain tunnel drainage test results and suggest water flow velocity to be a potentially important factor in calcium scale inhibition if magnets are used.