Bench scale experiments for the evaluation of a membrane filtration method for the recovery efficiency of Giardia and Cryptosporidium from water

The method of membrane filtration was evaluated regarding the recovery efficiency of Giardia cysts and Cryptosporidium oocysts from water. Equal volumes of distilled water were contaminated with a defined numbers of cysts and oocysts (1 × 10², 1 × 10³, 5 × 10³ and 1 × 10⁴ parasites l^-1) and filtered through a special membrane filter apparatus. After filtration, the recovered cysts and oocysts were identified using phase contrast microscopy and the number of cysts and oocysts were counted using a Neubauer haemocytometer. The average recovery rate obtained for Giardia cysts was 78.7% (range 61.1-105.9%), and for Cryptosporidium oocysts 42.1% (range 30.8-52.2%). The method had a superior efficiency for Giardia cysts comparable to Cryptosporidium oocysts, but there are no significant differences in recovery for Giardia cysts and Cryptosporidium oocysts using different initial concentrations of parasites.