AWWA WQTC60724

Recently a new test has been developed for assessing Cryptosporidiuminfectivity and viability based on cell culture propagation of life cycle stagesfollowed by identification and enumeration using real-time PCR (CC-PCR). Due to the test's simplicity and capability this has for the first timeallowed convenient assessment of disinfection effectiveness and permittedcomplex studies on the survival of the Cryptosporidium parasite in the naturalenvironment and through the water treatment process. This paper considers the early results from two Australian Cooperative Research Centre for WaterQuality and Treatment projects that tackle these issues. The first project focuses on the issue of whether certainwater treatment processes may in fact reduce the viability of oocysts orperhaps pre-stress oocysts making them more susceptible to subsequentdisinfection. The use of alum and ferric chloride coagulants atdifferent doses has been examined and no significant effect on viability hasbeen revealed using CC-PCR. The study also examined the influence ofchlorine and chloramine on coagulated oocysts and there appears to be nodiscernible effect either. In the second project the issue of environmental survival of oocysts incatchments prior to treatment was considered, with factors such assunlight and temperature being evaluated. So far, only water temperaturehas been fully evaluated but the results are striking in terms of theirimplications on catchment and reservoir management. While at 4°C oocystsremain viable for many months, as the temperature is raised to 37°C nearly4log₁₀ inactivation is evident after just 5 days. At a water temperature of25°C there is a 3Log₁₀ reduction in viability after 4 weeks. These periods aremuch less than calculated using the more conservative viability assayspreviously available. Includes 2 references.

Product Details

Edition:

Vol. - No.

Published:

11/15/2004

Number of Pages:

3

File Size:

1 file , 220 KB