Field investigations on the dispersion of aerosolized enteric bacteria and viruses generated by wastewater sprinkler irrigation were carried out at agricultural communities in Israel. One hundred and fifty-four air samples were taken in the vicinity of wastewater irrigated fields by two different methods: 1. Anderson multistage impactor air samplers and 2. High Volume Cyclone Scrubbers (HVCS). All night samples at 730 m. were positive for bacterial indicator organisms. 10% of the air samples by HVCS were presumptively positive for enteric viruses including 3 out of 24 samples taken at 730 m. downwind from the wastewater sprinkler fields. In 31% of the virus positive samples, none of the three bacterial indicators were detected. These findings suggest that aerosolized enteric viruses are more resistant to hostile environmental factors than the airborne bacterial indicator organisms. * This study was supported by a grant from the USEPA (CR 80-6416, Project officers: Mr. Walter Jakubowsky and Dr. Elmer Akin). It has not been subject to the Agency's peer and policy review and thus does not necessarily reflect the views of the Agency and no official endorsement should be inferred.

Humic and fulvic acids were tested for their ability to interfere with virus recovery by microporous filters. Two electropositively charged types of filter (Seitz S and Zeta Plus 60S) were used to concentrate poliovirus in the presence of humic materials. Humic acid inhibited virus adsorption, but even at the highest humic acid concentrations tested (200 mg/liter), 30 to 40% of the virus was recovered by the filters. Fulvic acid, tested with Zeta Plus filters, did not affect virus recovery. For comparison, two electronegatively charged filter types were tested (Cox and Balston). These two types of filter were more sensitive to interference at lower concentrations of humic acid than the more positively charged filters. With Balston filters, at humic acid concentrations above 10 mg/liter, most of the virus was recovered in the filtrate. Fulvic acid, tested with Balston filters, did not interfere with virus recovery. With the electropositively charged filters, the humic materials adsorbed efficiently, even at high input concentrations. Interference with virus adsorption occurred at humic acid concentrations which were below the level of saturation of the filters. In addition, in high-volume experiments, humic acid led to premature blockage of the filters. The efficiency of virus recovery by a second concentration step, organic flocculation of the filter eluate, was tested. For all the filter types tested, this procedure was not affected by the presence of humic or fulvic acid in the input water.

Simian rotavirus SA-11 was concentrated from tap water by adsorption to and elution from microporous filters, followed by organic flocculation. Two types of filters were compared for their ability to concentrate the virus. Both Zeta Plus 60S and Cox AA type M-780 filters were efficient for virus adsorption, but the efficiency of virus elution was higher with Zeta Plus than with Cox filters. Optimum conditions for virus recovery from Zeta Plus filters included an input water pH of 6.5 to 7.5 and the use of 3% beef extract (pH 9.0) for elution. Under these conditions, an average of 62 to 100% of the virus was recovered in the concentrate. Organic flocculation was used as a second-step concentration method, with average recoveries of 47 to 69%. When the two methods were used to concentrate small numbers (7 to 75 PFU/liter) of input rotavirus, an average of 75 ± 40% recovery was achieved. With large volumes of input water, however, recovery was reduced to 16 ± 7%.

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