AWWA ACE91023

This study performed fluoride tracer studies to determine actual clearwell disinfection contact times (CT) to verify compliance with the Surface Water Treatment Rule disinfection requirements. Clearwells at six water treatment plants were studied; all six treatment plants use chlorine gas as the disinfectant. This article describes the study background and methods, and the configuration of each treatment plant. Discussion and conclusions relate to both the contact times and at the treatment plants and the study methods. Regarding contact times, for example, the authors conclude that unbaffled clearwell storage can be used effectively to provide the required disinfection CT. Regarding the test methods, the authors conclude that the step-dose method is the preferred test method, even if fluoride feed equipment doesn't exist at the treatment plant. The authors recommend that for plants with two clearwells operating in parallel, consideration should be given to increasing the chlorine dosage to meet the CT requirements if one clearwell is out of service for repairs. Or, maintenance should be performed in the summer when water temperatures are higher and the required CT is lower and easily met with only one clearwell in service.

Product Details

Published:

01/01/1991

ISBN(s):

0898675898

Number of Pages:

25

File Size:

1 file , 760 KB