Data presented demonstrate the relatively high multiplicity of solids-associated virus in field samples, i.e., wastewater, sludge, and soils. Influent, effluent, and chlorinated effluent samples showed 16.1 to 100% of the total virus demonstrated in samples to be solids associated. Three techniques for freeing solidsassociated virus are described and compared. Using sonication of solids and polyethylene glycol concentration, virus was demonstrated in fully digested sludge (60 days at 34 C), sand at the site of a sewer leak, and dried sludge cake and mud 900 m downstream from a sewage disposal site. These data emphasize the inadequacy of virus concentration techniques that do not include the processing of solids. In situ elution failed to free solids-associated virus.

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The survival of virus present in secondary effluents discharged into a cypress dome was studied. Isolations were made from concentrates of water drawn from 10-foot (304.80 cm) deep wells. Data presented show vertical and lateral virus movement as well as survival within the dome for 28 days during a period of heavy rains when no effluent was being applied. Due to the inefficiency of virus concentration procedures, it is proposed that much of the virus present was probably not demonstrated. A rapid, relatively inexpensive concentration technique for sewage influents and effluents is discussed.