Ali M A, Al-Herrawy A Z, El-Hawaary S E
Environmental Virology Laboratory, Department of Water Pollution Researches, National Research Centre, Dokki, Cairo 12311, Egypt.
Water Res. 2004 Nov;38(18):3931-9. doi: 10.1016/j.watres.2004.06.014.
In this study, two types of drinking water treatment facilities (two conventional drinking water treatment plants (DWTPs) and two compact units (Cus)) were compared referring to their production capacity. Water samples were collected from three main points: (a) different water treatment steps (b) washings of sand filters and (c) distribution system at different distances from the water treatment plants. Both viruses and protozoa were concentrated from each water sample by adsorption and accumulation on the same nitrocellulose membrane filters (0.45 microm pore size). Enteroviruses were detected by plaque infectivity assay in BGM cells and HAV, HEV and Norovirus were detected by RT-PCR. Giardia and Cryptosporidium were detected by conventional staining methods and PCR. The results revealed that enterovirus load at the intake ranged between 10-15 PFU/L for the two compact units and between 4.5 and 75 PFU/L for the two conventional DWTPs. The virus load in distribution system of the first type DWTPs at 1 km from the plant was the same as that of the intake. Viruses in the other type of treatment plants CUs at 1, 5 and 7 km, were much reduced. Investigation of raw water sediments of the two DWTPs showed enterovirus counts between 12 and 17.5 PFU/L. Virus count was reduced in sand of filters after washing. Giardia cysts were equally detected by microscopy and PCR in only intake samples of EL-Hawamdia CU (33.3%) and Meet Fares DWTP (50%). Cryptosporidium oocysts were equally detected by microscopy and PCR in intake samples of Abo EL-Nomros CU (100%), EL-Hawamdia CU (66.7%) and Fowa DWTP (50%). At Meet Fares DWTP three positive intake samples for Cryptosporidium were detected by PCR, compared with only two positive samples by microscopy. Giardia cysts and Cryptosporidium oocysts were detected in raw water sediment and sand of filters before washing. Only one sample from Meet Fares DWTP sand of filters after washing was positive for both Giardia and Cryptosporidium. It can be concluded that the poor microbial quality of the water may be due to improper operational skills and management of the various water treatment plants (especially at the two high capacity treatment plants).
在本研究中，参照两种类型的饮用水处理设施（两座传统饮用水处理厂（DWTPs）和两个紧凑型装置（CUs））的生产能力进行了比较。从三个主要点采集了水样：(a) 不同的水处理步骤；(b) 砂滤器的冲洗水；(c) 距水处理厂不同距离的配水系统。通过吸附并累积在相同的硝酸纤维素膜过滤器（孔径0.45微米）上，从每个水样中浓缩病毒和原生动物。通过在BGM细胞中进行噬斑感染性测定检测肠道病毒，通过RT-PCR检测甲型肝炎病毒、戊型肝炎病毒和诺如病毒。通过传统染色方法和PCR检测贾第虫和隐孢子虫。结果显示，两个紧凑型装置进水口的肠道病毒载量在10 - 15 PFU/L之间，两座传统DWTPs的肠道病毒载量在4.5至75 PFU/L之间。第一类DWTPs在距水厂1公里处的配水系统中的病毒载量与进水口相同。另一类处理厂CUs在1公里、5公里和7公里处的病毒载量大幅降低。对两座DWTPs原水沉积物的调查显示，肠道病毒数量在12至17.5 PFU/L之间。冲洗后砂滤器砂层中的病毒数量减少。仅在EL - Hawamdia CU（33.3%）和Meet Fares DWTP（50%）的进水口样本中，通过显微镜检查和PCR均检测到贾第虫包囊。在Abo EL - Nomros CU（100%）、EL - Hawamdia CU（66.7%）和Fowa DWTP（50%）的进水口样本中，通过显微镜检查和PCR均检测到隐孢子虫卵囊。在Meet Fares DWTP，通过PCR检测到三个隐孢子虫阳性进水样本，而通过显微镜检查仅检测到两个阳性样本。在原水沉积物和冲洗前的滤器砂层中检测到贾第虫包囊和隐孢子虫卵囊。Meet Fares DWTP冲洗后的滤器砂层中只有一个样本同时对贾第虫和隐孢子虫呈阳性。可以得出结论，水的微生物质量较差可能是由于各水处理厂（尤其是两座高产能处理厂）操作技能和管理不当所致。
