Iron and copper release in drinking-water distribution systems.* Unlined metal pipes are widely used in drinking-water distribution systems. * In the United States United States, officially United States of America, republic (2005 est. pop. 295,734,000), 3,539,227 sq mi (9,166,598 sq km), North America. The United States is the world's third largest country in population and the fourth largest country in area. , more than 60 percent of distribution pipes are composed of cast iron, ductile iron, and steel. * Copper pipe is a primary material for home plumbing systems. * Corrosion of unlined metal pipes is ubiquitous. * This corrosion can release contaminants that adversely affect health and water aesthetics. * Corrosion results from chemical reactions between finished water and pipe metals or plumbing fixtures. * It results in the formation of a solid corrosion product called scale. * Disruption of solid scale is undesirable. * Disruption typically releases more contaminants. * If the composition of water frequently varies, the equilibrium between the corrosion scale and the water is disrupted, and contaminant contaminant /con·tam·i·nant/ (kon-tam´in-int) something that causes contamination. contaminant something that causes contamination. release occurs. * A pilot study at the University of Central Florida “UCF” redirects here. For other uses, see UCF (disambiguation). UCF is a member institution of the State University System of Florida. UCF was founded in 1963 as Florida Technological University with the goal of providing highly trained personnel to support the Kennedy examined the effect on water quality of blending finished waters. * Waters from ground, surface, and saline sources were used. * The water treatment processes included -- lime softening, -- ferric sulfate coagulation coagulation (kōăg'y  lā`shən), the collecting into a mass of minute particles of a solid dispersed throughout a liquid (a sol), usually followed by the precipitation or ,
-- reverse osmosis reverse osmosis n. The movement of a solvent in the opposite direction from osmosis in such a manner that the solvent moves from a solution of greater concentration through a membrane to a solution of lesser concentration. , -- nanofiltration, and -- integrated membrane systems. * The waters were supplied to 18 pipe distribution systems (PDSs). * The PDSs were constructed from PVC PVC: see polyvinyl chloride. PVC in full polyvinyl chloride Synthetic resin, an organic polymer made by treating vinyl chloride monomers with a peroxide. , lined cast iron, unlined cast iron, and galvanized gal·va·nize tr.v. gal·va·nized, gal·va·niz·ing, gal·va·niz·es 1. To stimulate or shock with an electric current. 2. pipes. * Surface water had low alkalinity al·ka·lin·i·ty n. The alkali concentration or alkaline quality of a substance that contains alkali. alkalinity 1. the quality of being alkaline. 2. and high levels of sulfates after ferric sulfate coagulation. * Consequently this water caused the highest iron release. * Finished groundwater treated by the conventional method produced the lowest iron release. * But it produced the highest copper release. * The iron release from desalinated water was relatively high because of high chloride levels and low alkalinity. * Both iron and copper release behaviors were influenced by temperature. * When water sources are switched or new treatment processes are introduced, it is necessary to evaluate the corrosivity of the new water for the existing distribution system. * The indexes traditionally used to assess the chemical stability of finished waters are not effective at predicting iron and copper release. * Conductivity and alkalinity ratios may be used as a supplementary index. * Special attention should be paid to changes in alkalinity, conductivity, and pH. * If copper pipes are included in the distribution systems, finished water with extremely high alkalinity should be avoided. |
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