Results from UFC tests will enable direct comparison of DBP formation in different water sources. A new chlorination approach has been developed for assessing disinfection by‐product (DBP) formation under constant, yet representative conditions. The rationale used in the development of the uniform formation conditions (UFC) test and the results of a parametric sensitivity analysis are presented. Within the acceptable range of conditions, the DBP formation varied by less than 4 percent for the three waters examined. UFC test results will allow a direct comparison of DBP formation among different waters and allow the evaluation of how treatment changes affect DBP formation in a specific water.

Although these authors confirm that the RSSCT is able to predict the breakthrough behavior of full‐scale activated carbon columns, they emphasize the importance of obtaining a representative batch water sample for the RSSCT. The Information Collection Rule (ICR) will require that some utilities perform disinfection by‐product (DBP) precursor removal studies. The rapid small‐scale column test (RSSCT), a bench‐scale granular activated carbon (GAC) test designed to reduce time and costs associated with field‐scale studies, has been proposed as an alternative to evaluate GAC performance for the ICR. RSSCT scaling equations maintain similitude with full‐scale GAC systems, and therefore the RSSCT directly assesses the concentration breakthrough in a full‐scale GAC column. A review of past studies shows that the RSSCT has successfully predicted field‐scale performance for the control of natural organic matter and DBP precursors. The results of a current study emphasize the importance of obtaining a representative batch water sample for the RSSCT. A cost analysis based on using GAC to satisfy stage 1 and stage 2 requirements of the Disinfectants/Disinfection Byproducts Rule suggests that minimizing empty bed contact time will reduce capital costs associated with GAC contactors.

Optimized coagulation results in benefits ranging from DBP reduction to improved GAC run times. The effect of optimized coagulation on granular activated carbon (GAC) performance for removal of natural organic matter and control of disinfection by‐products was investigated. Coagulation optimized for total organic carbon (TOC) removal increased GAC run times by a factor of 2–3 over run times observed for GAC receiving conventionally treated water. The improved performance was mainly a result of reductions in influent TOC and pH after optimized coagulation, as compared with conventional pretreatment. Conventional coagulation prior to GAC was more cost‐effective than optimized coagulation, because of increased costs associated with the high alum dosages used in this study.

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