Two process changes were proposed at the Dalecarlia and McMillan water treatment
plants operated by Washington Aqueduct, a United States Army Corps of Engineers
organization. It was proposed at both plants to switch from alum to polyaluminum
chloride (PACl) and from chlorine gas to sodium hypochlorite for coagulation and
disinfection, respectively. However, throughout the proposed process changes, both
plants must maintain a finished water pH of 7.7±0.1 to meet their optimal corrosion
control treatment (OCCT) targets.
This paper addresses the analysis conducted to determine the changes that will be
needed at both plants' corrosion control processes to maintain the OCCT target pH of
7.7±0.1. The analysis includes computer modeling work, which was evaluated with
bench-scale testing.
Projections show that, following the switch to hypochlorite, it was necessary to add
acid feed capabilities at McMillan to stay within the target range. While acid was not
needed at Dalecarlia, significantly lower doses of lime was needed. Lime, caustic
soda, and acid dose projections were made for each plant. Includes tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 95 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 9 |
| Published : | 11/01/2007 |
