The effect of sewage sludge treatment processes on oocysts of <i>Cryptosporidium parvum</i>

Whitmore, T. N.; Robertson, Lucy J.

doi:10.1111/j.1365-2672.1995.tb01670.x

Cited by 36 publications

(26 citation statements)

References 9 publications

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“…However, the previously described effects of heat on the infectivity of ova and oocysts (26,37) on May 11, 2018 by guest http://aem.asm.org/ log 10 unit should guarantee reductions in the numbers of infectious oocysts of parasites to levels below the levels required by some guidelines (34,35). The results presented here suggest that after calibration studies it should be possible to determine the ranges for inactivation of naturally occurring bacteriophages that guarantee a range of reduction in the number of Salmonella cells.…”

Section: Discussionmentioning

confidence: 99%

Survival of Bacterial Indicator Species and Bacteriophages after Thermal Treatment of Sludge and Sewage

Mocé-Llivina

Muniesa

Pimenta-Vale

et al. 2003

Appl Environ Microbiol

139

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The inactivation of naturally occurring bacterial indicators and bacteriophages by thermal treatment of a dewatered sludge and raw sewage was studied. The sludge was heated at 80°C, and the sewage was heated at 60°C. In both cases phages were significantly more resistant to thermal inactivation than bacterial indicators, with the exception of spores of sulfite-reducing clostridia. Somatic coliphages and phages infecting Bacteroides fragilis were significantly more resistant than F-specific RNA phages. Similar trends were observed in sludge and sewage. The effects of thermal treatment on various phages belonging to the three groups mentioned above and on various enteroviruses added to sewage were also studied. The results revealed that the variability in the resistance of phages agreed with the data obtained with the naturally occurring populations and that the phages that were studied were more resistant to heat treatment than the enteroviruses that were studied. The phages survived significantly better than Salmonella choleraesuis, and the extents of inactivation indicated that naturally occurring bacteriophages can be used to monitor the inactivation of Escherichia coli and Salmonella.

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Section: Discussionmentioning

confidence: 99%

Survival of Bacterial Indicator Species and Bacteriophages after Thermal Treatment of Sludge and Sewage

Mocé-Llivina

Muniesa

Pimenta-Vale

et al. 2003

Appl Environ Microbiol

139

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“…This data contrasts with that of Stadterm an et al (1995) who found that anaerobic digestion at 37ÊC inactivated 90% of the oocysts within 4 h and 99.9% of the oocysts within 24 h. The contrastin g data may not only represent difference s in the anaerobic digester and isolate or age of oocysts used, but may also represent difference s in the techniques for assessing viability. Whereas Whitmore and Robertson (1995) utilised a vital dye technique for assessing viability with verificatio n by in vitro excystatio n, Stadterma n et al (1995) relied upon an in vitro exeystation technique with enumeration of sporozoites.…”

Section: Sludgementioning

confidence: 99%

“…Research on inactivatio n of Cryptosporidium oocysts during treatment of sludge has indicated that both therm ophilic aerobic digestion and sludge pasteuris ation at 55ÊC were effective treatments (Whitmore and Robertson, 1995) with complete inactivatio n at first sampling (24 h and 2 h respectiv ely). However, in a mesophilic anaerobic digester, although within the first three days die off was relatively rapid with approximately 80% reduction in viability, after 18 days a small proportion of the oocysts remained viable.…”

Section: Sludgementioning

confidence: 99%

Removal and destruction of intestinal parasitic protozoans by sewage treatment processes

Robertson¹,

Smith²,

Grimason³

et al. 1999

International Journal of Environmental Health Research

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This paper reviews the literature which addresses the occurrence of intestinal protozoan parasites in sewage as well as the removal and destruction of these pathogens in sewage treatment processes. The concentration of intestinal protozoa within sewage depends upon the catchment; the prevalence and intensity of human infection within the catchment; the contribution of animal waste to the sewage and the prevalence and intensity of animal infection within the catchment. Some research indicates that some sewage treatment processes may result in relatively high removal efficiencies of some intestinal protozoa, whereas other data indicate that the concentration of cysts and oocysts discharged in sewage effluent may be in the order of several thousand per litre. For some protozoan parasites, such as Cyclospora, Microsporidia and Isospora, knowledge is scarce on the potential importance of sewage in their transmission and their likely removal and destruction by sewage treatment processes.

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“…• C) aerobic digestion was effective at inactivating the oocysts of Cryptosporidium (108). Mesophilic anaerobic digestion (35 • C) inactivated 90% of oocysts after 18 days.…”

Section: Transport and Viability Through Water Treatment Processesmentioning

confidence: 99%

ENVIRONMENTAL ECOLOGY OF CRYPTOSPORIDIUM AND PUBLIC HEALTH IMPLICATIONS

Rose

1997

Annu. Rev. Public Health

197

129

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Cryptosporidium has become the most important contaminant found in drinking water and is associated with a high risk of waterborne disease particularly for the immunocompromised.There have been 12 documented waterborne outbreaks in North America since 1985; in two of these (Milwaukee and Las Vegas) mortality rates in the immunocompromised ranged from 52% to 68%.The immunofluorescence antibody assay (IFA) using epifluorescence microscopy has been used to examine the occurrence of Cryptosporidium in sewage (1 to 120 oocysts/liter), filtered secondary treated wastewater (0.01 to 0.13 oocysts/liter), surface waters (0.001 to 107 oocysts/liter), groundwater (0.004 to 0.922 oocysts/ liter) and treated drinking water (0.001 to 0.72 oocysts/liter).New rules are being developed (Information Collection Rule and Enhanced Surface Water Treatment Rule) to obtain more occurrence data for drinking water systems for use with new risk assessment models. Public health officials should consider a communication program to physicians treating the immunocompromised, nursing homes, develop a plan to evaluate cases of cryptosporidiosis in the community, and contribute to the development of public policies that limit contamination of source waters, improve water treatment, and protect public health.

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The effect of sewage sludge treatment processes on oocysts of Cryptosporidium parvum

Cited by 36 publications

References 9 publications

Survival of Bacterial Indicator Species and Bacteriophages after Thermal Treatment of Sludge and Sewage

Survival of Bacterial Indicator Species and Bacteriophages after Thermal Treatment of Sludge and Sewage

Removal and destruction of intestinal parasitic protozoans by sewage treatment processes

ENVIRONMENTAL ECOLOGY OF CRYPTOSPORIDIUM AND PUBLIC HEALTH IMPLICATIONS

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