In order to meet the Stage 1 and future Stage 2 Disinfectant and Disinfection Byproducts
Rules, the Cobb County-Marietta Water Authority has completed an intensive pilot-scale
evaluation of advanced treatment technologies for disinfection byproduct (DBP)
precursor removal at the 72-million-gallons-per-day (mgd) Wyckoff water treatment
plant (WTP). The authority had observed elevated DBP levels in the distribution system,
and due to the fact that several consecutive systems purchase water from multiple sources
and areas with extended hydraulic residence time, simple solutions such as decreasing
chlorine dose or switching to chloramines were not options.
The study was conducted over a 12-month period by the authority and its consultant,
CDM, utilizing a two-train pilot-scale treatment plant. One train was used to simulate
existing rapid mixing, flocculation, sedimentation, and filtration treatment processes to
provide a baseline comparison, while the second train was used to evaluate the effect of
adding various DBP precursor reduction technologies to the existing Wyckoff WTP
treatment process train. Technologies evaluated in the study included pre-chlorine
dioxide in lieu of prechlorination, pre- and intermediate-ozone/biofiltration, magnetically
enhanced ion exchange (MIEX), and post-filter nanofiltration.
Results of the study indicated the ability of the Wyckoff plant to significantly lower DBP
levels to meet Stage 1 requirements by switching to chlorine dioxide as a pre-oxidant in
lieu of prechlorination. Ozone/biofiltration did not have an incremental difference in the
results for DBP precursor removal compared to pre-chlorine dioxide. Both pretreatment
with MIEX and post-filter nanofiltration provided significant reduction in DBP
precursors, allowing these technologies to be considered for future implementation to
meet Stage 2 DBP requirements. Includes reference, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 360 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 13 |
| Published : | 11/02/2003 |
