Newer membrane concentration processes and their application to the detection of viral pollution of waters

HYPERFILTRATION using a new type of membranes has emerged in the past few years as one of the fastest growing and potentially useful methods for concentration and/or separation of macromolecular materials. The process, as it is used for concentration and detection of viral particles, treats the virus as the macromolecuiar species. In membrane hyperfiltration two methods of dehydration are applicable. First, the virus-containing solution is placed under pressure (Pressure Ultrafiltration) and is forced to flow past the surface of a supported membrane. The lower molecular weight species such as water or dissolved salts pass through the membrane and that retained is collected as a concentrate. Second, the transport of water out of a virus containing solution is achieved through an osmotically induced flow (Osmotic Ultrafiltration). In this case, the membrane is impermeable to both virus and osmotic solution and water flows from the virus side to the osmotic side by direct osmosis. In the osmotic ultrafiltration system, asymmetric cellulose acetate heat treated membranes (reverse osmosis type) have aUowed for high water reduction with minimal effective membrane area. Similarly, pressure filtration using Amicon membranes (polyelectrolyte coacervate) can be used for water reduction and a comparative study of the two systems is indicated in TABLE 1.