ASSESSING POTENTIAL HEALTH RISKS FROM VIRUSES AND PARASITES IN RECLAIMED WATER IN ARIZONA AND FLORIDA, USA

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 infection model, risk of infection from 100 ml accidental ingestion ranged from approximately 2 x 10(-3) to 2 x 10(-4) for the levels of viruses and protozoa found in chlorinated secondary effluent and the risk was reduced to 2 x 10(-4) to 2 x 10(-6) with filtration and disinfection following activated sludge.