In this study, a method of estimating the ultimate concentration and the rate constant in a kinetic
model for disinfection byproduct (DBP) formation was developed by using a nonlinear regression technique to fit the
model to calculated water age (from water distribution system hydraulic models) and DBP field
sampling data from actual water distribution systems. To better understand the chemistry in
reactions of HAAs with elemental iron, and perhaps incorporate associated rate constant data in
distribution system water quality models, batch experiments were also conducted with varying
chlorine residual concentration and constant pH.
Results indicated that the regression method is fairly accurate in predicting HAA concentrations;
however, limitations were observed in the method's ability to predict peak concentrations. A big
advantage of this fitting technique is that it can potentially account for HAA biodegradation and
other distribution system reactions that are typically not characterized or quantified
experimentally in the traditional bottle tests. The lab results in this study indicated that DCAA
(dichloroacetic acid) was converted to CAA (chloroacetic acid), and that CAA did not degrade
further. BAA (bromoacetic acid) was converted to acetic acid. Rates did not seem to be
dependent upon the level of chlorine residual. There is still a lack of understanding of HAA
degradation rates under various conditions of pH, chlorine residual, and iron loading. Rate
constants extracted from more rigorous bottle tests, such as from these experiments, could
potentially be used in distribution system models to make better predictions of the amount and
distribution of HAAs. Includes 8 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 1.2 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 11 |
| Published : | 11/01/2009 |
