Neto R Cantusio, Santos L U, Franco R M B
Laboratory of Protozoology, Dept of Parasitology, University of Campinas (UNICAMP), Campinas, SP, Brazil.
Water Sci Technol. 2006;54(3):89-94. doi: 10.2166/wst.2006.453.
Among many waterborne diseases the giardiasis and cryptosporidiosis are of particular public health interest, because Giardia cysts and Cryptosporidium oocysts can persist for long periods in the environment, and both pathogenic protozoa have been implicated as the cause of many outbreaks of gastroenteritis in the last 25 years. In order to evaluate the efficiency of cysts and oocysts' removal by the activated sludge process, and by UV reactor in inactivating cysts and oocysts in one wastewater treatment plant (WWTP) of Campinas, three sampling points were selected for study: (1) influent, (2) treated effluent without UV disinfection and (3) treated effluent with UV disinfection. Giardia spp. cysts prevailed with higher density in the three different sample types. Cryptosporidium spp. oocysts were observed in only two samples of influent and just one sample of treated sewage with UV disinfection. In the animal infectivity assay for Giardia spp, one mouse of the UV treated group revealed trophozoites in intestinal scrapings. The results of the present study indicate that treatment by activated sludge process delivered a reduction of 98.9% of cysts and 99.7% of oocysts and UV disinfection was not completely efficient regarding the inactivation of Giardia cysts in the case of the WWTP studied.
在众多水传播疾病中，贾第虫病和隐孢子虫病尤其受到公共卫生关注，因为贾第虫包囊和隐孢子虫卵囊能在环境中长时间存活，并且在过去25年里，这两种致病原生动物都被认为是许多肠胃炎暴发的病因。为了评估活性污泥法去除包囊和卵囊的效率，以及紫外线反应器对坎皮纳斯一家污水处理厂中包囊和卵囊的灭活效果，选择了三个采样点进行研究：（1）进水，（2）未经紫外线消毒的处理后出水，（3）经过紫外线消毒的处理后出水。在这三种不同类型的样本中，贾第虫属包囊的密度更高。仅在两份进水样本和一份经过紫外线消毒的处理后污水样本中观察到隐孢子虫属卵囊。在针对贾第虫属的动物感染性试验中，紫外线处理组的一只小鼠肠道刮片中发现了滋养体。本研究结果表明，活性污泥法处理使包囊减少了98.9%，卵囊减少了99.7%，在所研究的污水处理厂中，紫外线消毒对于灭活贾第虫包囊而言并非完全有效。
