Corrosion in a distribution system can lead to colored
water caused by source water iron and manganese.
In addition, corrosion problems may cause the system to
fail to meet the Lead and Copper Rule (LCR) action
levels. This study was undertaken to demonstrate that
sodium silicate addition can achieve corrosion control
for the LCR and simultaneous sequestration of iron and
manganese at an LCR-classified medium water system
that has multiple wells and entry points.
At special study monitoring sites, an initial silicate
dosage of 25-30 mg/L elevated the pH from 6.3 to 7.1
and resulted in a 55% reduction in lead levels and an
87% reduction in copper levels. A further increase to
45-55 mg/L silicate dosage increased the pH to 7.5
and produced even greater reductions in lead and copper.
The treatment change reduced 90th percentile lead
and copper levels by at least 95%, enabling compliance
with the LCR. Study results showed that the
aesthetic quality of the drinking water after treatment
was equal or superior to the water's quality before the
treatment. The higher pH and silicate combination
was also found to be more compatible with protecting
asbestos-cement and cement-lined pipes than
polyphosphate treatment at a lower pH. Includes 34 references, table, figures.
| Edition : | Vol. 97 - No. 11 |
| File Size : | 1
file
, 400 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 10 |
| Published : | 11/01/2005 |
