评估了硅藻土过滤对地表水中贾第虫、隐孢子虫、浊度和大肠菌群的去除效果。还研究了阳离子聚合物和明矾对这种去除的影响。基本上所有的贾第虫囊肿和>99。9%的隐孢子虫卵囊从含有约2000个囊/升的水中去除。使用明矾进一步改善了隐孢子虫的去除。当添加化学混凝剂时，大肠菌群和浊度，尤其是小颗粒（3μm或更小）的去除率也更高。 由于水头损失更大，使用这些化学品可以缩短过滤器运行的长度，即使是对于低浊度的水也是如此。包括14个参考文献、表格和图表。

Diatomaceous earth filtration was evaluated for removal of Giardia muris, Cryptosporidium, turbidity, and coliform bacteria from a surface water. The effect of cationic polymers and alum on this removal was also investigated. Essentially all of the Giardia cysts and >99.9 percent of Cryptosporidium oocysts were removed from waters containing approximately 2,000 cysts/L. The removal of Cryptosporidium was further improved by using alum. Greater removals of coliforms and turbidity, especially small particles (3 um or less), were also achieved when chemical coagulants were added. Use of these chemicals reduced the length of filter runs, even for low-turbidity waters, because of higher head losses. Includes 14 references, tables, figures.