Sequential inactivation of Cryptosporidium parvum oocysts with ozone and free chlorine

Driedger, A.; Rennecker, Jason L.; Mariñas, Benito J.

doi:10.1016/s0043-1354(00)00097-x

Cited by 95 publications

(70 citation statements)

References 11 publications

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“…Data for the analysis are listed in Tables 1 and 2 (Tables 1 and 2). Tables 1 and 2 While previous work suggests that Cryptosporidium oocyst inactivation follows a second-order kinetic model (Korich et al 1990;Rennecker et al 1999;Driedger et al 2000), the The results from this study indicate that a free chlorine Ct value of 15,300 (at pH 7.5) is needed to achieve a 3-log inactivation of C. parvum oocysts originating from a Maine outbreak and 10,400 for oocysts originating from calves in Iowa. While previous studies of C. parvum disinfection rates focused on inactivation using free chlorine, most were focused on drinking water conditions and have used excystation and/or mouse infectivity to determine oocyst Values are rounded to three significant digits.…”

Section: Calculations and Statistical Analysismentioning

confidence: 53%

“…Excystation has been used in most C. parvum disinfection studies, with mouse infectivity occasionally employed to verify the calculated disinfection rates (Korich et al 1990;Driedger et al 2000;Corona-Vasquez et al 2002). Excystation assays tend to underestimate the rate of inactivation because such measurements do not account for oocysts that are able to excyst and release sporozoites, which while capable of infiltrating cells are unable to produce an actual infection (Black et al 1996;Bukhari et al 2000;Joachim et al 2003).…”

Section: Cryptosporidiummentioning

confidence: 99%

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Inactivation of Cryptosporidium parvum under chlorinated recreational water conditions

Shields

Hill

Arrowood

et al. 2008

Journal of Water and Health

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Cryptosporidium is a chlorine-resistant protozoan parasite and the etiological agent in many disinfected recreational water outbreaks. While previous studies have reported disinfection Ct values for Cryptosporidium parvum using sodium hypochlorite, these studies have employed conditions and procedures which are not ideal for establishing public health remediation recommendations for chlorinated recreational water venues. In the present study, free chlorine Ct values were measured at pH 7.5 using young oocysts (,1 month old) and tissue culture to determine oocyst viability. Two different oocyst isolates were used: one originating from Iowa and one from Maine (USA). This study determined that the Ct values for a 3-log reduction in oocyst viability were 10,400 (Iowa) and 15,300 (Maine) at pH 7.5. These Ct values are higher than the Centers for Disease Control and Prevention (USA) currently recommends (Ct ¼ 9,600) for achieving a 3.0-log inactivation of Cryptosporidium oocysts during remediation of recreational water venues following fecal diarrhea accidents.

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Section: Calculations and Statistical Analysismentioning

confidence: 53%

Section: Cryptosporidiummentioning

confidence: 99%

Inactivation of Cryptosporidium parvum under chlorinated recreational water conditions

Shields

Hill

Arrowood

et al. 2008

Journal of Water and Health

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“…ozone) followed by a weaker oxidant (i.e. free or combined chlorine) could produce important synergistic effects on the deactivating kinetics of strong pathogens such as Cryptosporidium parvum oocysts Driedger et al, 2000;2001). The high efficiency demonstrated by sequential disinfection using the ozone-chlorine pair could be related to the generation of different reactive oxygen species (i.e.…”

Section: Sequential Disinfection Using Solar-driven Fenton-like Procementioning

confidence: 99%

Safe Drinking Water Generation by Solar-Driven Fenton-Like Processes

Corona-Vasquez¹,

Aurioles²,

Bandala³

2012

Solar Radiation

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“…Due to its relatively high resistance to free chlorine, its control is a particular problem for water treatment works. Several studies have reviewed the superior efficacy of ozone for control of C. parvum (Staehlin and Hoigné, 1985;Korich et al, 1990;Gyürék et al, 1999;Driedger et al, 2000;Rennecker et al, 2000). Because of the large CT value for C. parvum (up to 5 mg O 3 ·min·l -1 ) its reaction with ozone is chosen to indicate the disinfection performance of the contactor.…”

Section: Ct Concept and The Disinfection Purpose Of Ozonementioning

confidence: 99%

Application of computational fluid dynamics modelling to an ozone contactor

Huang¹,

Brouckaert²,

Pryor³

et al. 2004

WSA

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Computational fluid dynamics (CFD) modelling has been applied to examine the operation of the pre-ozonation system at Wiggins Waterworks, operated by Umgeni Water in Durban, South Africa. A hydraulic model has been satisfactorily verified by experimental tracer tests. The turbulence effect induced by the gas injection was modelled by increasing the level of turbulence intensity at the ozone contactor inlet. The simulated tracer response corresponded closely to the experimental results. The framework of ozone reaction modelling was subsequently investigated using values of rate constants from the literature. The predicted profile of residual ozone concentration suggests the current operating strategy can be improved to optimise the ozone utilisation. The wide range of values found in the literature suggests that the ozone reactions are strongly dependent on site-specific characteristics of the water. Further experimental work is required to determine rate constants which are applicable to water from the Inanda Dam.

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Sequential inactivation of Cryptosporidium parvum oocysts with ozone and free chlorine

Cited by 95 publications

References 11 publications

Inactivation of Cryptosporidium parvum under chlorinated recreational water conditions

Inactivation of Cryptosporidium parvum under chlorinated recreational water conditions

Safe Drinking Water Generation by Solar-Driven Fenton-Like Processes

Application of computational fluid dynamics modelling to an ozone contactor

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