SEDL / STP / STP976-EB / STP26717S

Recovery of Naturally Occurring Rotaviruses during Sewage Treatment

Chalapati Rao, V
Associate professor of environmental virology, professor of environmental virology, and distinguished service professor of virology and epidemiology, Department of Virology and Epidemiology, Baylor College of Medicine, Houston, TX

Metcalf, TG
Associate professor of environmental virology, professor of environmental virology, and distinguished service professor of virology and epidemiology, Department of Virology and Epidemiology, Baylor College of Medicine, Houston, TX

Melnick, JL
Associate professor of environmental virology, professor of environmental virology, and distinguished service professor of virology and epidemiology, Department of Virology and Epidemiology, Baylor College of Medicine, Houston, TX

Pages: 6    Published: Jan 1988

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Abstract

Human enteric viruses occur in large numbers in sludges and in aquatic sediments from polluted waters. Of these agents, rotaviruses are often involved in water- and food-borne outbreaks. They represent health hazards of undetermined magnitude. Virus levels in sludges may be reduced, but the viruses are not eliminated by aerobic and anaerobic treatment. A study of the removal of indigenous rotaviruses during the primary settling and activated sludge treatment of raw sewage was conducted for a period of 8 months in a Houston, TX, plant treating 5.55 million L per day. An average rotavirus reduction of 44 to 55% was obtained by primary settling and a reduction of 93 to 99% was achieved in the final chlorinated effluents. Composite sampling at 1-h intervals over a 24-h period indicated average removals of 85%—a measure much more accurate than the misleading average of 6% indicated by one series of grab samples of raw sewage and effluent collected simultaneously. Quantification of rotaviruses was based on counts of immunofluorescent foci 24 h after addition of sample concentrates to coverslip cultures of fetal rhesus monkey kidney cells. Rotavirus quantities ranged from 40 to 510 per liter of raw sewage and from 0 to 25 per liter in the final chlorinated effluent.