Physicochemical mechanisms responsible for the filtration and mobilizationof a filamentous bacteriophage in quartz sand

This study examines the influence of pore water chemistry on the filtration and physicochemical properties of a male-specific filamentous bacteriophag e isolated from chlorinated effluent of the San Jose Creek Water Reclamatio n Plant in Los Angeles County, California. The isolate belongs to a class o f bacteriophage that are naturally present in sources of sewage, and hence may be an indicator of fecal contamination in groundwater. Furthermore, the re is some evidence that this class of bacteriophage are mobilized in the s ubsurface following rainfall events, although the mechanism responsible for this process is not yet clear. Using a model filtration system consisting of packed columns of quartz sand, we found that the filtration of this isol ate was strongly dependent on the concentration and valence of the dominant cation in the pore fluid. In one set of experiments involving columns 19 c m in length, virus retention in the column increased from 0% to 99.999% whe n the electrolyte composition of the pore fluid was changed from 10 mM NaCl to 10 mM CaCl2. With one exception, filtration efficiencies calculated fro m the column experiments were inversely proportional to the electrophoretic mobility of the virus, implying that electrostatic interactions between th e virus and the quartz surface dominate the filtration dynamics of this par ticular bacteriophage. From a practical perspective, these results indicate that small changes in the hardness and total dissolved solids of pore flui ds - as might occur following a rainfall event - can dramatically affect bo th the filtration and mobilization of filamentous bacteriophage in subsurfa ce systems. (C) 1998 Elsevier Science Ltd. All rights reserved.