Virus adsorption to mineral surfaces is reduced by microbial overgrowth and organic coatings.

In experiments with strains of poliovirus, reovirus, echovirus, and Coxsackievirus, overgrowth with exopolymer-forming bacteria reduced virus adsorption to mineral surfaces. Adsorption was improved when organic materials adsorbed to minerals were removed by low-temperature ashing. In a soil series, virus adsorption increased with soil depth. This paralleled a decrease in organic content, but differences in charge development of the soil particles may also be involved. Prolonged (40-year) irrigation with treated sewage effluents, leading to a buildup of organic coatings, also decreased adsorption. However, saturation of the virus-binding capacity of the soil as a result of continuous exposure to virus-containing effluents was not apparent.