The growing concern of public opinion over possible adverse health effects derived from
exposure to halogenated disinfection byproducts (DBPs) in drinking water and the more
stringent demands of present and upcoming DBP regulations (Stage 1 DBPR and Stage 2
DBPR) have stimulated the interest of many utilities in exploring the effectiveness of
alternative strategies that may be implemented without requiring major capital
investments.
This paper presents and compares the results and the implications of bench-scale testing
commissioned by four different utilities in the Eastern U.S. These utilities use
conventional surface water treatment processes with a variety of coagulation and
disinfection schemes. Disinfection practices include the use of chlorine and chlorine
dioxide for pre-oxidation and primary disinfection, and chlorine and chloramination for
secondary disinfection.
The tests were conducted to investigate modifications of the treatment process targeted to
lowering DBP levels in the plants as well as changes in finished water chemistry that
focused on maintaining acceptable DBP levels even in remote areas of the system
without compromising disinfection goals. Treatment plant modifications included:
enhancement of precursor removal, optimization of disinfectant application point, and
curtailing excessive disinfectant application. Simulated distribution system tests focused
on studying the effects of lowering the pH of finished water, lowering chlorine residuals,
and replacing free chlorine with combined chlorine for secondary disinfection.
The results of these studies illustrate trends in trihalomethane (THM) and haloacetic acid
(HAA) levels resulting from each individual alternative or combination of the alternatives
tested. More importantly, the analysis of test results clearly defined the benefits of each
option and the ranking of the options available to each utility for control of DBP levels in
its system. Full-scale modifications are currently being implemented at the four utilities
discussed in this paper.
Includes 3 references, tables.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 270 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 12 |
| Published : | 11/01/2002 |
