The Water Institute at UNC, Department of Environmental Sciences and Engineering, University of North Carolina at Chapel Hill, Campus Box 7431, Chapel Hill, NC 27599, USA.
Water Res. 2011 Aug;45(14):4092-102. doi: 10.1016/j.watres.2011.05.008. Epub 2011 May 17.
The biosand filter (BSF) is a household slow sand filter that is operated intermittently such that an idle time of typically 18-22 h occurs in between daily charges of water. Virus attenuation during the idle time was investigated over repeated daily filtration cycles to capture the effect of media aging that encompasses processes occurring throughout the filter depth rather than restricted to the schmutzdecke at the media surface. A threshold aging period of about one to two weeks was required before virus attenuation began. The observed rates of MS2 and PRD-1 reduction were first-order and reached maxima of 0.061- and 0.053-log per hr, respectively, over seven-to-ten weeks. Suppression of microbial activity by sodium azide eliminated virus reduction during the idle time thus indicating that the operative media aging process was microbially mediated. The mechanism of virus reduction was not modification of media surfaces by physical/chemical or microbial processes. Instead, it appears that the activity of the microbial community within the filter is responsible. The most likely biological pathways are production of microbial exoproducts such as proteolytic enzymes or grazing of bacteria and higher microorganisms on virus particles. Implications of these findings for BSF design and operation and their relevance to other biological filtration technologies are discussed.
生物砂滤器（BSF）是一种家用慢砂滤器，间歇性运行，每天给水泵水时会有一个典型的 18-22 小时的空闲时间。在重复的每日过滤循环中研究了空闲时间的病毒衰减情况，以捕捉涵盖整个过滤深度的过程的介质老化效果，而不仅仅是限于介质表面的污垢层。在病毒衰减开始之前，需要大约一到两周的阈值老化期。观察到 MS2 和 PRD-1 的减少速率均为一级，在七到十周内分别达到 0.061-和 0.053-log/hr 的最大值。亚硫酸钠抑制微生物活性，从而消除了空闲时间的病毒减少，表明有效的介质老化过程是微生物介导的。病毒减少的机制不是物理/化学或微生物过程对介质表面的修饰。相反，似乎是过滤内微生物群落的活性负责。最有可能的生物途径是微生物外产物的产生，例如蛋白酶或细菌和更高的微生物对病毒颗粒的吞噬。这些发现对 BSF 设计和操作的影响及其与其他生物过滤技术的相关性进行了讨论。
