| This study evaluated the potential of riverbank filtration (RBF) to improve water quality. RBF is the process whereby a well is dug a specific distance from a river, enabling a hydraulic flow from the river into the well. During ground passage, water-borne microorganisms are removed or inactivated. RBF can be used where costly water treatment is unavailable and as a primary water treatment to enhance existing water treatment process.;To evaluate the impact of RBF on water quality, this study examined the transport of MS2 and PRD1 bacteriophage, poliovirus type 1 (PV1), E. coli and C. perfringens spores, and C. parvum oocysts through 30 cm- and 15 cm-long and 2.8 cm-wide columns packed with Potomac River sediment. The effects of pH, ionic strength, and temperature on the ability of these microorganisms to pass through soil material were tested. Additionally, virus survivability and infectivity after RBF were evaluated by differentiating infective viruses, detected using infectivity tests, from infective and inactivated viruses, detected by quantitative reverse transcription polymerase chain reaction (qRT-PCR).;The results showed that no E. coli, C. perfringens spore or C. parvum oocyst broke through any sediment columns, and only 23% of PV1, 34% of MS2, and 37% of PRD1, (average) broke through 30 cm long column. These indicate that microorganism size and surface characteristics play an important role in virus transport through soil. Of the three parameters tested, higher ionic strength and low pH increase virus attachment to sediment during column passage. Temperature, however, had no effect on virus transport. Lower temperature increased virus survival and lower pH decreased virus survival over time. Column passage decreased MS2 die off but increased PV1 die off.;qRT-PCR was shown to be a sensitive detection method. However, it can over-estimate health risks since it detects both infective and inactivated viruses. qRT-PCR can therefore only be used for a rapid assessment of water quality. To accurately assess health risks requires further analysis using viral infectivity assays.;In conclusion, Potomac River sediment can effectively remove and inactivate microorganisms during sediment passage, thereby improving water quality. Real-life RBF with longer passage times through finer sediments should be even more effective in improving water quality. |
