Tech. Vol. 23, Kyoto, pp. 2091-2098, 1991. Printed in Great Britain. All rights reserved. ... South Florida, 13301 Bruce B. Downs Blvd., Tampa, FL 33612, USA.
Wat. Sci. Tech.
Vol.
23,
Kyoto, pp.
2091-2098, 1991.
0273-1223/91 $0·00 + ·50 1990 IAWPRC
Printed in Great Britain. All rights reserved.
Copyright ©
ASSESSING POTENTIAL HEALTH RISKS FROM VIRUSES AND PARASITES IN RECLAIMED WATER IN ARIZONA AND FLORIDA, USA Joan B. Rose * and Charles P. Gerba * * • Department
of Environmental and Occupational Health, University of
South Florida, 13301 Bruce B. Downs Blvd., Tampa, FL 33612, USA • * Department
of Microbiology and Immunology and Nutrition and Food
Science, Bldg. 90,
University of Arizona, Tucson, AZ 85721, USA
ABSTRACT Wastewater reuse has been mandated in both the states of Arizona and Florida, U.S.A. In Arizona, standards have been set for enteric virus and Giardia levels to maintain a specified effluent quality depending on the reuse, while in Florida, specified treatment control has been implemented. Data on virus levels in treated wastewaters have been generated in both states. Average virus levels ranged from 13-130 pfu/100L after secondary treatment while with the addition of filtration, levels were reduced to averages between 0. 13 to 1. 25 pfu/100L. Giardia cyst levels also dropped by 100 fold after filtration averaging 0.32/40L. Using a probability of infec;:tion model, ri� of infectio � from 100 ml accidental ingestion _ . ranged from approxlmately 2 x 10 to 2 x 10 for the levels of Vlruses and pro ozoa found n chlorinated secondary effluent and the risk was reduced to 2 x 10- to 2 x 10- with filtration and disinfection following activated sludge.
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INTRODUCT ION The growing demand on existing water supplies has been a major incentive for communities in arid climates such as Arizona to locate new resources. However, states such as Florida even with the greater rainfall are also facing a water crisis due to uneven rain distribution, population growth and years of drought. One alternative source for both states is reuse domestic wastewater. In the united States, greater than one mill � m per day of wastewater are used for agriculture and landscape irrigation. In Arizona and Florida such reuse has been mandated for ground water protection rules and long-term water preservation plans. A major concern with the reuse of wastewater, however, is the possible In order to presence of pathogenic microorganisms and potential health risks. address these risks, standards governing the occurrence of viruses and pararites in treated wastewater destined for reuse have been implemented in Arizona and specified treatment control has been required in Florida.
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2 Over 120 possible enteric viruses may be found in sewage. These viruses have the capacity for producing an immense range of diseases in humans, such as diagrhea, aseptic meningitis, paralysis, conjunctivitis, myocarditis and hepatitis. The major viruses include enteroviruses (polioviruses, echoviruses, coxsackie viruses) , rotaviruses, Norwalk viruses, hepatitii A virus, which may be found at 2 levels as high as 492, 000 viral units per liter. The protozoa Giardia and Cryptosporidium have been identified as important causes of waterborne disease, producing a gastrointestinal illness. Both parasites are able to survive and penetrate routine wastewater treatment. The cysts and oocysts (the environmental infectious stages) are routinely found in ser;fgf Ch has ' 4, undergone secondary treatment at levels as high as 100 to 1000/L.
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The State of treatment in
Arizona established standards to demonstrate the reliability of maintaining a specific water quality for renovated wastewater.
2091
2094
J.
B. ROSE and C. P. GERBA
Testing for viruses and protozoa was used for determining the occurrence of theBe pathogens, demonstrating appropriate and reliable treatment, and evaluating the potential health risks depending on the type of reuse. The standard for viruses is currently divided into two categories: For those areas with restricted access irrigation the A. standard has been set to 125 enteric viruses/40 L. For unrestricted access irrigation the standard has been set to 1 B. enteric virus/40 L. For the parasites, the standard set for Giardia is less than 1 cyst/40 L and the state is considering a similar standard for Cryptosporidium. Treatment requirements in Florida depend on first the type of reuse and potential for public exposure. For the purposes of this paper we will discuss the type of reuse using reclaimed water for public access irrigation, edible crops, fire protection, toilet flushing, construction, dust control, and aesthetic purposes. Mandatory treatment for this type of reuse is secondary treatment, filtration with coagulant aids and high level disinfection. Monitoring is required for fecal coliforms which must be
