Full Description

Corrosion in a distribution system can lead to coloredwater caused by source water iron and manganese.In addition, corrosion problems may cause the system tofail to meet the Lead and Copper Rule (LCR) actionlevels. This study was undertaken to demonstrate thatsodium silicate addition can achieve corrosion controlfor the LCR and simultaneous sequestration of iron andmanganese at an LCR-classified medium water systemthat has multiple wells and entry points.At special study monitoring sites, an initial silicatedosage of 25-30 mg/L elevated the pH from 6.3 to 7.1and resulted in a 55% reduction in lead levels and an87% reduction in copper levels. A further increase to45-55 mg/L silicate dosage increased the pH to 7.5and produced even greater reductions in lead and copper.The treatment change reduced 90th percentile leadand copper levels by at least 95%, enabling compliancewith the LCR. Study results showed that theaesthetic quality of the drinking water after treatmentwas equal or superior to the water's quality before thetreatment. The higher pH and silicate combinationwas also found to be more compatible with protectingasbestos-cement and cement-lined pipes thanpolyphosphate treatment at a lower pH. Includes 34 references, table, figures.

Product Details

Edition: Vol. 97 - No. 11 Published: 11/01/2005 Number of Pages: 10File Size: 1 file , 400 KB