Evaluation of different filtration techniques for the concentration of cryptosporidium oocysts from water

The relative performances of different filter matrices were assessed for the concentration of Cryptosporidium oocysts in water. Cartridge filtration methods were examined and compared with membrane filtration and a flocculation method using seeded tap and river water to determine the most efficient and consistent method of sample concentration. From 10L samples, calcium carbonate flocculation gave the most consistently high recovery rate of Cryptosporidium oocysts (tap water mean 72.9%; river water mean 41.9%), followed by membrane filtration using 1.2μm cellulose acetate membranes (tap water mean 37.8%; river water mean 26.6%). For filtration of larger volumes (>100L) of water the Cuno Microwynd II cartridge filter provided the highest recovery rate of oocysts (tap water mean 13.3%; river water mean 10.8%) when compared with the Vokes cartridge and Balston filters. All recoveries fell dramatically when sucrose flotation techniques were applied.