AWWA ACE91028

One method of water treatment that has proved effective in reducing lead contamination involves treating the water with sodium hydroxide to raise the initial pH and sodium bicarbonate (NaHCO3) to provide 25- 30 ppm alkalinity as CaCO3. This methodology replicates the natural hardening and pH adjustment process that occurs in limestone subsoils. The town of Bennington, Vermont, implemented this type of water treatment 14 years ago, with good immediate and long-term results. This paper describes Bennington's corrosive water supply and the corrosion control system. Raw filtered water (pH 4.5-6.0) flows into the clearwell, through a series of baffles, toward the distribution pump. A pH probe monitors the water leaving the clearwell. The probe signals a solution metering pump to adjust the flow of a dilute solution of NaOH into the clearwell in order to raise the pH of the water to a set point of 8.3. The description of the process continues, following the water through the system. The monitoring and sampling plan, which meets USEPA regulations, is outlined.

Product Details

Published:

01/01/1991

ISBN(s):

0898675898

Number of Pages:

13

File Size:

1 file , 340 KB