Protecting groundwater from viral contamination by soil modification

During land application of domestic wastewater, pathogenic enteric viruses may gain entrance into groundwater. Soil modification to enhance virus removal as a method of groundwater protection is described. Inorganic substances were added to a column of sandy loam to assess their ability to enhance the removal of coliphage MS-2 and poliovirus from tapwater and secondarily treated sewage. Aluminum metal, magnesium oxide and magnesium peroxide when added to the soil were found to significantly enhance virus removal above that observed in control columns. Powdered metallic aluminum caused an average decrease of greater than five logs in virus concentration, while control columns containing no aluminum showed only a two log decrease. Significant reduction in the number of viruses continued in test columns during five weeks of intermittent flooding. The efficiency of virus removal due to the soil additive declined toward the end of the flooding period. Aluminum metal did not significantly change the pH of the column percolate and was not leached in significant amounts from the soil used in this study when pH 2–3 water was passed through the column for 38 days. Both magnesium oxide and magnesium peroxide, while also effective in virus removal, significantly increased the pH of the column percolate.