Removal of
Total Organic Carbon
A Technical Review
© 2004 Dr. John T. O’Connor

GAC-Capped Filter,Bloomington, Illinois

H2O’C Engineering
(877) 22-WATER www.h2oc.com Alternatives to TOC Removal Requirements: Direct Measures of DBP Formation

Since public health concerns center around the formation of DBPs, it seems reasonable to employ the most direct known parameters of DBP production during treatment and distribution and use these established measures to establish a more uniform and rational limit for drinking waters to meet independent of source, system size, alkalinity or other externalities.
It is clear that USEPA recognizes that TTHM and HAA5 provide some measure of overall DBP formation. The near-absence of the compounds that constitute these groups should be some indication that unknown DBPs, although varied in composition, have not been formed in large measure.
Disinfectant Persistence
Another indicator useful for operation and system monitoring should be the depletion of the disinfectant residual. If a residual remains persistent over a prolonged period (e.g., days and weeks), it may be assumed that DBP formation reactions are not proceeding rapidly. This can be a particularly important water system monitoring procedure because the measurement of disinfectant residual is routinely practiced at utilities that practice disinfection.
Following our recommendation, a number of Midwestern systems are currently following a simple monitoring program to determine the persistence of their finished water residual under ideal (clean pipe) and field (dirty pipe) conditions. To assess disinfectant loss in the clean pipe, finished water is stored in darkness in a clean glass bottle. Aliquots are removed over a period of hours to days to weeks to observe disinfectant residual persistence.
An example of a disinfectant residual persistence study for an ammonia-bearing