AWWA QTC97139

In 1996, the City of Englewood, Colorado, initiated the upgrade of the Charles Allen Water Treatment Plant to improve plant reliability and to meet the more stringent requirements of the proposed microbial and disinfection byproduct (DBP) regulations. Pilot-scale evaluation of free chlorine application to the raw, settled and filtered waters produced interesting results regarding the formation of DBPs in relation to the removal of natural organic matter (NOM) as measured by total organic carbon (TOC). DBPs, particularly the brominated and mixed chloro-bromo trihalomethanes and haloacetic acids, were observed at higher concentrations as TOC removal was improved through filtration or higher coagulant doses as compared to TOC levels in the settled waters. These increases in DBP concentration, combined with the shift in speciation, resulted in an estimated 15 to 20% greater carcinogenic risk based on available health effects data. The marginal improvement for TOC removal beyond that observed for turbidity removal also resulted in increased solids production and projected treatment costs. This paper discusses the procedures, results and implications of the coagulation and DBP testing conducted for the City of Englewood.

Product Details

Published:

01/01/1997

ISBN(s):

0898679583

Number of Pages:

31

File Size:

1 file , 270 KB