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 Giarrdia cysts and Cryptosporidium oocysts from water. Equal volumes of distilled water were contaminated with a defined numb ers of cysts and oocysts (1 x 10(2), 1 x 10(3), 5 x 10(3) and 1 x 10(4 ) parasites l(-1)) and filtered through a special membrane filter appa ratus. After filtration, the recovered cysts and oocysts were identifi ed using phase contrast microscopy and the number of cysts and oocysts were counted using a Neubauer haemocytometer. The average recovery ra te obtained for Giardia cysts was 78.7% (range 61.1-105.9%), and for C ryptosporidium oocysts 42.1% (range 30.8-52.2%). The method had a supe rior efficiency for Giardia cysts comparable to Cryptosporidium oocyst s, but there are no significant differences in recovery for Giardia cy sts and Cryptosporidium oocysts using different initial concentrations of parasites. (C) 1998 Elsevier Science Ltd. All rights reserved.