INACTIVATION OF CRYPTOSPORIDIUM PARVUM USING INTERNATIONAL WATER TECHNOLOGIES' pHBLANCER

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Abstract:

The pHBalancer is a novel continuous flow disinfection device. It combines traditional electrochemical technology with an innovative reactor design and flow pattern to achieve near-instantaneous inactivation of numerous microorganisms including Cryptosporidium parvum oocysts. CRYPTOSPORIDIUM PARVUM oocysts, less than 4 weeks of age, were seeded into 10 liters of tap water at a concentration of approximately 104/mL. Influent samples were collected in sterile 250 mL tubes while effluent samples were collected using sterile 250 mL tubes containing 10% sodium thiosulfate to neutralize the residual disinfectant. Oocysts present in influent and effluent samples were concentrated by centrifugation and their infectivity determined using the FDM-MPN (cell culture) assay.

Cell culture technology has developed into a tool that can be used to study CRYPTOSPORIDIUM PARVUM in an environment most similar to in-vivo studies without using animal models. In the cell culture system, the reproductive cycle of C. parvum begins after 12 hours incubation and by 48 hours an average of 17.9 foci (sites of infection) to infectious oocysts ratio can be observed for non-disinfected oocysts. Presumably, non-synchronous excystation and infection occurs during the organisms complex life cycle forming clusters of reproductive stages in the host cell monolayer. These life stages can be detected and enumerated microscopically using a Most Probable Number (MPN) methodology. Two experimental conditions were evaluated: 1) 5 minute contact 2) 20 minute contact time within the time within the pHBalancer. The International Water Technologies' pHBalancer was able to achieve a >3.5 log10 inactivation of CRYPTOSPORIDIUM PARVUM oocysts after a five minute contact time within their unit. Because of the low number of oocysts in the influent it was not possible to determine the whether there was a measurable increase in the inactivation of C. parvum by the pHBalancer after a 20 minute contact time within the unit.

The water industry is always seeking innovative disinfection technologies that are capable of inactivating highly resistant organisms such CRYPTOSPORIDIUM PARVUM. The pHBalancer does not require the addition of a brine or salt solution to produce a disinfection solution nor are its objectives to produce an end product that has to be mechanically injected and mixed into a waste stream to achieve disinfection. The pHBalancer can be used to disinfect almost any water or wastewater as long as there is a small amount of chloride present. While it has been documented that the electrolysis of chloride containing waters can produce a mixture of various oxidants such as hypochlorous acid, chlorites, chlorine dioxide, ozone, peroxides and other oxidizing free radicals, the pHBalancer has demonstrated a synergy and treatment approach unreported previously.

Document Type: Research Article

DOI: http://dx.doi.org/10.2175/193864700784547197

Publication date: January 1, 2000

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  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

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