Control of new copper corrosion in high-alkalinity drinkina water

摘要

Research and field experience have shown that highalkalinity waters can be associated with elevated copper levels in drinking water. The objective of this study was to document the application of orthophosphate (PO_4) to the distribution system of a building with a copper problem associated with high-alkalinity source water. The alkalinity and pH of the water were 273 mg/L calcium carbonate and 7.4, respectively, and copper levels at taps ranged from 1.4 to 2.4 mg/L. Experimental bench-scale jar tests proved to be useful for establishing an appropriate orthophosphate dose. A simple chemical feed system delivered orthophosphate to the building at a dose of approximately 3 mg/L PO_4. Within several weeks, copper levels throughout the building dropped below the Lead and Copper Rule copper action level of 1.3 mg/L. Orthophosphate levels remained consistent across the building and did not change during stagnation. The addition of orthophosphate also increased the chlorine residuals of flushed water samples.