Full Description

As part of the proposed Stage 2 Disinfectants/DisinfectionByproducts Rule (Stage 2 D/DBPR), utilities will have to reassess thelocation of samples collected for DBP compliance monitoring. This iscomplicated by the various trends observed for the different classesof DBPs in distribution systems, as well as within each class, and bythe fact that different subclasses of haloacetic acids (HAAs) areexpected to peak at different locations because of their differentchemical properties. The results described here give utilities additionalknowledge and tools to help them select their sampling locationsfor DBP monitoring as part of the proposed Stage 2 D/DBPR.To carry out the work, simulated distribution systems (annularreactors) were placed in two parallel trains at the effluent of a fullscaletreatment plant: one train received chlorinated water and theother chloraminated water. Each train was composed of two annularreactors in series. The upstream annular reactor received waterwith a disinfectant residual, and the downstream annular reactorreceived dechlorinated or dechloraminated water. The effect of DBPcontact with biofilm formed in the absence of corrosion byproducts,with and without a chlorine or chloramine residual, was addressedin both cold and warm waters.Trihalomethanes (THMs) and HAAs continued to form in thedistribution system in the presence of a free chlorine residual butremained relatively unchanged in the presence of a chloramineresidual. In the absence of a chlorine residual, some of the HAAspecies remained unchanged in cold water but were degraded inwarm water. Other HAA species showed different trends in theabsence of a disinfectant residual, but in general, concentrationsremained unchanged. In the absence of a disinfectant residual(either free chlorine or chloramines), THM concentrationsremained relatively unchanged. Includes 23 references, table, figures.

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Edition: Vol. 97 - No. 2 Published: 02/01/2005 Number of Pages: 13 File Size: 1 file , 410 KB