Bacteriophages are potentially useful models for studying the fate and transport of pathogenic enteric viruses and other biocoUoids through soil and ground water. To be useful for this purpose they must be capable of surviving for significant periods in ground water and demonstrate low adsorption to soil surfaces. The purpose of this study was to evaluate the survival of two bacteriophages which have been shown to adsorb poorly to soils, i.e. the Escherichiacoli phages MS-2 and PRD-1 which infect Salmonellatyphimurium. Samples of ground water from various regions of North America were inoculated with the test phages and incubated at temperatures near the ambient ground water temperature of the collection site. At 7°C no significant inactivation of the phages occurred over a period of 80 days. At higher temperature (10 to 23°C) PRD-1 was far more resistant to inactivation than MS-2, persisting for periods of 7 to 10 times longer in most water samples.

Water utilities, especially smaller ones, are having increasing difficulties proving increased treatment requirements required in the United States for the removal of chemical and microbial contaminates in drinking water. This project sought to evaluate the virus removal potential of combined slow sand filtration and nanofiltration by a pilot plant for application to a small utility which uses a surface water supply. Nanofiltration is a relatively new water treatment technology which has become available since 1986. It is similar to reverse osmosis but has a higher molecular weight cut-off and is less costly to operate. The bacteriophages MS-2 (28 nm) and PRD-1 (65 nm) were seeded into surface water entering a pilot plant and samples collected after sand filtration, nanofiltration, and of the nanofilter reject water. These phages were selected for study because of their small size and poor adsorption to surfaces. The slow sand filter removed 99% of the MS-2 and 99.9% of the PRD-1. There was between a 4 to 6 log reduction of the phages by the nanofilters. PRD-1 was removed to a greater extent than MS-2 by both the sand filter and the nanofilters.

Development of the need for personal water treatment devices has evolved from consumer interest in improving and ensuring the quality of drinking water. The need also extends to the quality of untreated or partially treated waters such as that used by hikers, campers, recreational home and boat owners, and families or communities having individual home and small system water sources. It is essential that such devices be capable of removing all types of pathogenic microorganisms likely to be found in contaminated water. For this reason the U.S. Environmental Protection Agency has suggested such units be capable of removing Klebsiella terriaena. Giardia cysts and enteric viruses. Three identical water purifiers were evaluated for the inactivation of rotavirus SA-11, hepatitis A virus, poliovirus type 1, the bacterial virus MS-2, Klebsiella terriaena and Giardia muris cysts. The units depend upon a thermal cycler combined with activated carbon for removal of the test organisms. The units were challenged with the organisms suspended in tapwater after 4, 76 and 240 cycles of operation. The units were also tested with a “worst case” water quality of 1500 mg/l dissolved solids, 10 mg/l organic matter and with a water turbidity of 30 NTU. In all cases, complete inactivation of the viruses, bacteria and cysts occurred after operation of the 35-minute cycle. This resulted in a greater than 3-log (99.9%) inactivation of cysts, a greater than 6 log (99.9999%) inactivation of K. terriaena and 4-log (99.99%) inactivation of viruses. In conclusion, these units would comply with CTiteria guidelines suggested by the U.S. Environmental Protection Agency for the operation of microbial water purifiers.