EVALUATION OF DIFFERENT FILTRATION TECHNIQUES FOR THE CONCENTRATION OF CRYPTOSPORIDIUM OOCYSTS FROM WATER

The relative performances of different filter matrices were assessed f or the concentration of Cryptosporidium oocysts in water. Cartridge fi ltration methods were examined and compared with membrane filtration a nd a flocculation method using seeded tap and river water to determine the most efficient and consistent method of sample concentration. Fro m 10L samples, calcium carbonate flocculation gave the most consistent ly high recovery rate of Cryptosporidium oocysts (tap water mean 72.9% ; river water mean 41.9%), followed by membrane filtration using 1.2 m u m cellulose acetate membranes (tap water mean 37.8%; river water mea n 26.6%). For filtration of larger volumes (>100L) of water the Cuno M icrowynd II cartridge alter provided the highest recovery rate of oocy sts (tap water mean 13.3%; river water mean 10.8%) when compared with the Vokes cartridge and Balston filters. All recoveries fell dramatica lly when sucrose flotation techniques were applied.