Inhibiting lead corrosion in drinking water systems - by adding soluble carbonate and maintaining pH at specified level

摘要

The process comprises adding to the water a source of water soluble carbonate in an amt. necessary to assure the passivation of the pipes comprising lead contg. elements. The pH of the water is maintained at 7.5-9. Pref. the carbonate content, expressed as CaCO2 is maintained at a minimal amt. of about 20mg/l. The water pH is maintained at 0.5-9 in a manner to form a layer of lead carbonate to assure the passivation of the lead. The process is partic. applied to drinking water, usually of lower pH and low carbonate content, which is corrosive to lead resulting in too high a lead content in the water (normal environmental limit 0.5mg/l). The method is very effective whereas previous processes such as pH adjustment or adding orthophosphate are limitedly effective and ineffective respectively.