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US EPA Research on Monochloramine Disinfection Kinetics of Nitrosomonas europaea
Citation:
WAHMAN, D., K. A. KLEIER, AND J. G. PRESSMAN. US EPA Research on Monochloramine Disinfection Kinetics of Nitrosomonas europaea. Presented at EPA Workshop on Small Drinking Water Systems: Challenges and Solutions, Cincinnati, OH, August 04 - 06, 2009.
Impact/Purpose:
To inform the public.
Description:
Based on utility surveys, 30 to 63% of utilities practicing chloramination for secondary disinfection experience nitrification episodes (American Water Works Association 2006). Nitrification in drinking water distribution systems is undesirable and may result in water quality degradation (e.g., disinfectant depletion, coliform occurrences, or nitrite/nitrate formation) and subsequent non-compliance with existing regulations (e.g., Surface Water Treatment Rule or Total Coliform Rule). As a first step toward gaining better information on ammonia-oxidizing bacteria (AOB) disinfection in chloraminated drinking water distribution systems, a culture-independent method with future applicability to mixed-culture AOB was implemented with Nitrosomonas europaea. The culture-independent method combines propidium monoazide (PMA), which selectively removes DNA from membrane-compromised cells and/or inhibits its amplification by PCR (Nocker et al. 2007), with a quantitative PCR (qPCR) method (Figure 1) developed for detection of AOB in chloraminated drinking water distribution systems (Regan et al. 2007). The results using PMA-qPCR were compared with those obtained using another culture-independent membrane integrity based technique, LIVE/DEAD® BacLight™ (LD) (Figure 2), that was previously used to etermine N. europaea monochloramine disinfection kinetics (Oldenburg et al. 2002).