Development criteria for ultraviolet disinfection of unfiltered drinking water

紫外光已被证明对隐孢子虫和贾第鞭毛虫等水媒寄生虫有效，并迅速被用于水处理中的过滤饮用水消毒。然而，由于人们对水中颗粒和其他杂质对紫外线消毒效果的影响知之甚少，紫外线在劣质水源(如未经过滤的地表水)中的使用一直受到限制。建议的研究的广泛目标是提高对水质变量如微生物浓度、颗粒物、溶解和胶体有机物如何影响未经过滤的天然水的紫外线消毒的认识。研究隐孢子虫卵囊的聚集和相互作用枯草杆菌芽胞和其他含有颗粒存在于未经过滤的天然水和合成水基质中的替代微生物将在实验室实验中进行研究。此外，还将开发一种方法，用于对含有低浓度种子微生物的水样进行紫外线照射。由于对隐孢子虫的研究非常昂贵和困难，替代微生物将用于紫外线灭活研究。替代微生物在各种未过滤的天然水和合成水基质中的聚集和颗粒相互作用将被测量，并与台式紫外线暴露实验中测量的灭活水平相关联。这项研究的预期最终产品是水质指数或方便的标准测试，水处理工程师可以使用它来预测当使用UV对特定的未过滤供水进行消毒时所提供的公共健康保护水平。

Ultraviolet (UV) light has been shown to be effective against waterborne parasites such as Cryptosporidium and Giardia and is rapidly being adopted in water treatment for disinfection of filtered drinking water.   The use of UV for poor quality water sources, such as unfiltered surface water, has been limited because the effect of particles and other impurities in the water on the effectiveness of UV disinfection is poorly understood.   The broad objective of the proposed research is to improve the knowledge of how water quality variables such as microorganism concentration, particulate matter, and dissolved and colloidal organic matter, affect UV disinfection of microorganisms unfiltered natural water.  Aggregation and interaction of Cryptosporidium oocyst, Bacillus subtilis spores and other surrogate microorganisms with particles present in unfiltered natural water and synthetic water matrices will be investigated in laboratory experiments.  A method for conducting UV exposures with water samples containing low concentrations of seeded microorganisms will also be developed.   Because research with Cryptosporidium is very expensive and difficult, surrogate microorganisms will be used for UV inactivation studies.   Aggregation and particle-interaction of surrogate microorganisms in a variety of unfiltered natural water and synthetic water matrices will be measured and correlated with the level of inactivation measured in bench-top UV exposure experiments.  The anticipated end product of this research is a water quality index or a convenient standard test that could be used by water treatment engineers to predict the level of public health protection provided when UV is used to disinfect specific unfiltered water supplies.