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HUMAN ENTERIC VIRUS SURVIVAL IN SOIL FOLLOWING IRRIGATION WITH SEWAGE PLANT EFFLUENTS
Citation:
Sagik, B., B. Moore, AND C. Sorber. HUMAN ENTERIC VIRUS SURVIVAL IN SOIL FOLLOWING IRRIGATION WITH SEWAGE PLANT EFFLUENTS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/1-80/004.
Description:
The wastewater treatment processes at Kerrville and Uvalde, Texas, were evaluated in terms of their efficacy in reducing human enteric viruses. (Data on the reduction of TOC, BOD5, suspended solids, orthophosphate, nitrogenous compounds, total coliform, fecal coliform, and bacteriophage were also obtained). Enteric viruses were reduced by greater than 99% at Kerrville and at least 99% at Uvalde. These waters are used for irrigation without disinfection. Soil samples at the Kerrville and Uvalde application sites yielded both fecal coliforms and bacteriophages. In addition, two confirmed enterovirus isolations were made at the Kerrville site. Lysimeters placed 1.5 ft, 3.0 ft, and 4.5 ft depths at the Kerrville site yielded large numbers of bacteriophage isolates. In addition, ten lysimeter samples yielded a total of 29 confirmed viral isolates. This is a strikingly high number of isolations of indigenous enteric viruses, relative to the irrigation pond which was demonstrably low in viruses (when assayed on the same cell lines). Cell changes (CPE) but no confirmed isolations were made from five monitoring wells. These studies of wastewater treatment plants processing dilute to moderate strength sewage in efficient treatment schemes represent a 'best possible case' for the use of undisinfected, domestic wastewater effluents for irrigation. The isolation of enteroviruses in water from lysimeters but not from the monitoring wells suggests that depth to groundwater should be a critical factor in the selection of irrigation sites. From data developed in this study, it appears that a depth of 4.5 ft is not sufficient for effective viral attenuation in soils such as those described in this report.