犹他州环境质量部对通过直接过滤和常规治疗去除贾第虫和隐孢子虫囊肿进行了为期两年的评估，该评估由美国环保局赞助。在全尺寸水处理厂将包囊接种在穗中，并在中试厂以逐步剂量连续接种；两者均在常规处理和直接过滤条件下运行。使用2.0μm膜过滤进行处理前后的取样。使用15毫升试管中的Percoll浮选法和2.0微米孔隙率聚碳酸酯膜过滤器上的IFA染色法检测囊肿，并使用荧光显微镜进行计数。在900 gpm处理厂进行的8个包囊接种试验和在0.5 gpm中试厂进行的20个试验的结果表明，原水质量（浊度和藻类含量）以及去除浊度的处理效果，控制着种子贾第虫和隐孢子虫包囊的去除。 在播种试验之间观察到的原水水质变化对去除率的影响大于处理方式。与隐孢子虫卵囊（2.6-log）相比，贾第虫囊肿（3.1-log）的去除率一直较高。囊肿清除率和相应大小颗粒的清除率之间存在高度相关性；囊肿和浊度去除之间的相关性较差，而囊肿的去除和异养细菌之间没有相关性。

A two-year evaluation of Giardia and Cryptosporidium cyst removal through direct filtration and conventional treatment, sponsored by the USEPA, was conducted by the Utah Department of Environmental Quality. Cysts were seeded in a spike at a full scale water treatment plant, and continuously in a step dose at a pilot plant; both operated under conventional treatment and direct filtration regime. Sampling before and after treatment was conducted using 2.0 um membrane filtration. Cysts were detected using Percoll flotation in 15 mL tubes and IFA staining on 2.0 um porosity polycarbonate membrane filters, and enumerated using epifluorescent microscopy. The results of 8 cyst seeding trials, conducted at a 900 gpm treatment plant, and 20 trials, conducted in a 0.5 gpm pilot plant, indicated that raw water quality (turbidity and algal content), as well as treatment effectiveness in removing turbidity, controlled the removal of seeded Giardia and Cryptosporidium cysts. Changes in raw water quality, observed between the seeding trials, influenced removal rates more than the mode of treatment. Higher removal rates were consistently observed for Giardia cysts (3.1-log) than for Cryptosporidium oocysts (2.6-log). A high correlation was found between cyst removal rates and removal of the respective size particles; poorer between the cysts and turbidity removal, while no correlation was established between the removals of cysts and heterotrophic bacteria.