A census of viruses through the drinking water cycle
Final Report Abstract
To be able to measure even very low concentrations of viruses in Water, for instance to control the safety criteria for drinking water, a method had to be validated for concentrating large volumes of water by filtration holding back a large spectrum of viruses for detection by cultural or molecular biological methods. After successful development and validation in the lab, the method had to be evaluated for its use in different waters for quantitative and qualitative virus analysis. The filtration module we used has a 7-hole multibore capillary membrane with a maximal pore size of 0.02 µm. The total filtration area of the module was 4.5 m². With a flow rate of up to 2 m³ / h we were able to filtrate more than 30 m³ of drinking water. We found mean recovery rates for somatic coliphages depending on the elution buffer between 34 and 67.3 % with cultural methods. PCR-recovery rates of murine Noroviruses in the same test setting were found to be 27.5%. The validated module was tested concerning the recovery rate by filtrating drinking water, surface water and treated sewage. Drinking water filtration was possible with unchanged flow rate to at least 30 m3.Treated sewage and surface water were filtrated of up to 2 m3 taking into account the high amount of other microorganisms disturbing the (cultural) virus detection. In surface water and treated sewage recovery rates of 45% resp. 69% compared to direct plating analysis could be found. As expected, the filtration capacity of the module was significantly reduced when filtrating untreated sewage. By cultural detection methods it could be shown, that the filtration module can be flushed and disinfected to make possible a save reuse without cross contamination.
