This project focused on investigating the impact of various parameters on the formation of
NDMA upon chloramination of organic polymers used in drinking water treatment. Specifically,
the project was designed to answer the following questions:
do anionic or nonionic polymers used in drinking water treatment also form NDMA;
what is the impact of polymer dose on NDMA formation;
what is the impact of chloramine contact time on NDMA formation;
what is the impact of free chlorine contact time, upstream of ammonia addition, on
downstream NDMA formation;
what is the impact of water pH on NDMA formation from polymers; and,
do the polymer storage conditions affect its potential to form NDMA? While the testing was conducted in organic-free deionized laboratory water, its
results should provide specific insights to water agencies on how to manage the chloramine-polymer
interaction and minimize NDMA formation at their plants.
All bench-scale activities were conducted by Water Quality & Treatment Solutions (WQTS) at the Environmental Engineering
Laboratory of the University of California, Los Angeles (UCLA). NDMA samples were analyzed
by the Water Quality Laboratory of the Metropolitan Water District of Southern California
(MWDSC). All DMA samples were analyzed by Dr. David Sedlak's research group at the
University of California Berkeley (UCB). At the beginning of the project, WQTS conducted a
survey of the polymers used by the sponsoring agencies. Based on the results of the survey,
WQTS and the agency representatives advising WQTS on the project selected twelve
polymers to be evaluated. Eight of these polymers were cationic polymers, two were
anionic polymers, and two were nonionic polymers.
The bench-scale tests focused on contacting polymer solutions with chloramine under various
water quality and experimental conditions, and analyzing the product water for NDMA and DMA.
Seven tests were initially planned and
conducted, but two additional tests were added later on in the project. In all tests, various
solutions of polymers were prepared in Nanopure® water. With the exception of Test 3, the
chemical addition sequence was chlorine, followed by ammonia, and then followed by polymer.
The chloraminated water was first prepared in bicarbonate-buffered Nanopure® water. The
alkalinity of the buffered water was maintained between 95 and 100 mg/L as CaCO<sub>3</sub>. The
chloraminated water was then split into amber glass bottles to which the target polymer doses
were added. All chemical solutions were prepared in Nanopure® water. Includes 11 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 460 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 19 |
| Published : | 06/17/2004 |
