RESUMO
Approximately 3,200 L of water were inoculated with Cryptosporidium oocysts and Giardia cysts. The contaminated water was filtered through a Berkefeld Filter, type TWA 3, as used by the Norwegian army. Nine 10-L samples of filtered water and four 10-L control samples of unfiltered water were analyzed for Cryptosporidium oocysts and Giardia cysts. On average, 1,920 Giardia cysts and 2,735 Cryptosporidium oocysts per 10 L were detected in the unfiltered water. Between 0 and 2 Giardia cysts and between 2 and 47 Cryptosporidium oocysts were detected in the filtered 10-L samples. Percentage removal of parasites was between 99.8 and > 99.95% for Giardia (2.98 to > 3.28 log removal) and between 98.3 and 99.9% (1.76-3.14 log removal) for Cryptosporidium. The Berkefeld filter TWA 3 complies with published recommendations for municipal water supply for removal of Giardia but does not always comply with such regulations for Cryptosporidium.
