The objective of this study was to increase the understanding of dihalogenated haloacetic acid (DXAA) formation during
chloramination in the presence of bromide. This research proposes that the variability in
DXAA formation and speciation is associated with the relative concentrations of the
different haloamine species and their varying reactivities. Therefore, a better
understanding of haloamine speciation in the presence of bromide under the range of
conditions encountered in drinking water treatment, as well as the reactivity of the
various haloamine species in forming DXAA, will allow development of better
approaches for minimizing DXAA formation. The experiments conducted to characterize the reactivity of the bromamines in forming
HAAs are summarized in the paper. The natural waters were dosed with preformed
bromamine stock solutions. Simultaneously, the concentrations of the individual
bromamine species in the stock solutions were measured spectrophotometrically. The pH
of the water matched that of the dosing solution to ensure that the bromamine speciation
did not change upon dosing. The dose was selected to provide a target residual
concentration between 0.5 and 1 mg/L as Cl<sub>2</sub> at 24 hours. Samples were incubated in
brown glass bottles and capped headspace free with Teflon-lined septa. HAA9 samples
were taken at 5 minutes and again at 0.5, 1, 4, 24, 48, and 72 hours and extracted
immediately to avoid complications that may arise due to sample preservation. Total
combined oxidant concentrations were measured alongside the HAA samples to
determine total oxidant demand. To study the influence natural waters may have on
bromamine demand, control experiments were run with carbonate buffered Millipore
water under the same experimental conditions as the bromamine reactivity experiments
outlined in the paper. The carbonate concentrations were added to match the concentration
found in the natural waters. In addition, several controls were also run with chloramines
instead of bromamines to determine relative differences in reactivity. These experiments
were conducted at the same pH, buffer concentration, and initial haloamine dose as the
bromamine reactivity experiments, but were dosed with preformed chloramines instead
of bromamines. Includes 8 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 320 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 11 |
| Published : | 06/01/2006 |
