A Stage 3 DBP Rule in Texas - If Chloramine Can’t Get Us There, Will GAC?
- Ben Stanford PhD, Buddy Boysen PE, John Erickson Ph.D. - Hazen and Sawyer
With more stringent disinfectant/disinfection byproduct (D/DBP) rules, and the US EPA indicating a potential Stage 3 DBP Rule on the horizon with the 6-year review of the D/DBP rules in 2016, utilities are evaluating advanced techniques to optimize their current treatment processes as well as look towards future treatment improvements. New DBPs that could be wrapped into a Stage 3 rule include nitrosamines such as NDMA, and potentially expanding from the 5 currently regulated haloacetic acids (HAAs) to a suite of 9 HAAs. Chloramine use has been a popular approach to managing the current Stage 2 DBPs of HAA5 and trihalomethanes (THMs), but it has the potential to create more NDMA. For other utilities, GAC has been an ideal solution for removing THM and HAA5 precursors, but recent research has indicated that GAC may allow more of the brominated DBPs that are more genotoxic to form. GAC is also much more expensive than some of the other DBP control options while chloramine use requires careful management of chemical feed ratios and the distribution system to avoid nitrification events. Additionally, some activist groups have made a strong push in communities around the US to force utilities to abandon chloramine as a DBP control strategy.
Lead author, Ben Stanford, recently presented a national webcast on the state of science regarding many of the concerns surrounding chloramine use and provided answers to many of the questions regarding disinfectant choice and DBP control options. Dr. Stanford is also leading a current Water Research Foundation project (WaterRF 4560) that is investigating the formation of regulated and unregulated DBPs with GAC use at bench, pilot, and full-scale sites. As such, this presentation will provide the audience with information on three major topics: (1) What is the basis behind a potential Stage 3 DBP rule and how does it impact Texas? (2) With Texas having the highest percentage of systems reporting NDMA during national monitoring programs, how does disinfectant choice impact potential compliance with a Stage 3 rule? And (3) What is the latest science behind GAC use, chloramine use, and formation of NDMA, THMs, HAA9, and other DBPs of concern? Data for this presentation will come directly from WaterRF Project 4560 in addition to several on-going or recently-published Foundation reports and peer-reviewed literature. The presentation will have some technical content but will be designed to provide meaningful information to a broad range of audience member backgrounds.
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