In this study, the effect of mixing was examined by conducting breakpoint chlorination experiments
under different levels of mixing, represented by the average velocity gradient, G in s<sup>-1</sup>. A rather
unique way of plotting breakpoint chlorination curve was utilized to analyze the data, which
allowed a clear delineation if the monochloramine formation was according to the stoichiometry.
A quantitative comparison between experimental data and stoichiometry can clearly indicate the
impact of non-uniform mixing. The experimental data showed that as the G value increased from
35 to 500 s<sup>-1</sup>, the monochloramine formation increased from 75 to 87 percent of the
stoichiometric value. The location of the breakpoint, correspondingly, increased from a molar
ratio of 1.25 to 1.75.
Comparison of 50- and 200-rpm experimental data was conducted and a breakpoint curve was
plotted imposing one over the other. It has been observed from previous literature that in ideal
conditions, breakpoint occurs at chlorine to ammonia nitrogen molar ratio of 1.5:1, and the peak
of monochloramine is expected at a molar ratio of 1:1. Hence, breakpoint curve was plotted at
mixing speed of 50 and 200 rpm, indicating free chlorine, monochloramine, dichloramine,
trichloramine, and total chlorine concentration at contact time of 45 minutes.
In conclusion, when chlorine and ammonia are combined to produce monochloramine, the
degree of mixing indeed has significant impact on the performance of the chloramination
process, and therefore must be a critical consideration in its design and operation. Includes 12 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 2.4 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 47 |
| Published : | 11/01/2009 |
