The waterborne protozoan parasites Cryptosporidium parvum and C. hominis have emerged as the most frequently recognized cause of recreational water-associated outbreaks of gastroenteritis, particularly in venues utilizing chlorination (bleach). The number of confirmed cases increases every year, and the number of outbreaks more than doubled in 2006 compared to previous years (MMWR reports, CDC). Further, in February of 2008, the Centers for Disease Control and Prevention (CDC) revised its fecal accident CT inactivation value recommendations for 99.9% inactivation of Cryptosporidium from 9,600 mg-min/L to 15,300 mg-min/L. This change translates into longer swimming pool closures after an accidental fecal release. Of the five outbreaks reported to CDC in 2006, one occurred at a pool using UV, indicating that immediate disinfection in the pool is critical. Like UV, chlorine-based mixed oxidants were originally developed for use in the municipal water market over 10 years ago. These oxidants are produced on site from salt, water, and electricity, and stored so that proper dosing may be achieved based on bather load and resulting free available chlorine (FAC). Note that this technology is not a salt water chlorinator so the pool remains free of salt. Numerous studies show that mixed oxidants inactivate a wide range of microorganisms faster than traditional chlorination technologies at the same FAC doses. Included in this list of microorganisms is the Cryptosporidium parvum oocysts. The work of four independent laboratories has shown that when tests are performed correctly, mixed oxidants are consistently able to inactivate Cryptosporidium parvum oocysts more efficiently than chlorine (bleach) alone. The second half of the talk will present data collected from two MOS-treated pools which reveal striking features. Third, evidence from pool studies indicate that accumulated Total Organic Carbon (TOC) concentrations from the Body Fluid Analog (BFA) added continuously by bathers are significantly lower than those reported in the literature for bleach-treated model pools. The data will be presented in context with possible chemical mechanisms consistent with the observations. Susan B. Rivera, Ph.D., is the Manager of Research and Development at MIOX Corporation. MIOX Corporation designs and manufactures onsite generators of hypochlorite (bleach) and mixed oxidants for a variety of customers and applications including recreation water venues, cooling towers, shipboard use, individual water purification systems for the military, and municipal water treatment plants. Rivera interfaces with water sector representatives and water science experts and plays a key role in understanding mixed-oxidant chemistry relative to other disinfection technologies. Rivera earned her doctorate in biochemistry from the University of Utah. She commenced postdoctoral work in bionanomechanical system characterization and assembly with a diverse team of engineers and material scientists at Sandia National Laboratories before redirecting her efforts towards International Biological Threat Reduction and Homeland Security. During Rivera’s two year policy position, she participated in security assessments at U.S. government bioscience facilities, and contributed to the development of international biosecurity guidelines. In her current position, Rivera assists stakeholders in the area of water security. Rivera is also a NSPF Certified Pool/Spa Operator®.
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