"Managing reclaimed water by pretreating before using it to irrigate, monitoring for viruses, choosing correct crops and periodically leaching the soils should be successful and safe," said Dr. George Di Giovanni, Texas Agricultural Experiment Station environmental microbiologist.

Di Giovanni and his colleagues studied the movement of viruses carried in water through sandy and clay soils on which spinach was planted. They were interested in how long viruses in the water remain in the soil, how they move through the soil and whether they could harm humans or livestock. Their findings have been accepted for an article in Agriculture Ecosystems and Environment journal.

"No bacteriophage (virus) was found on the spinach leaves, regardless of the type of soil they grew in," Di Giovanni said.

The tests were done in a greenhouse in soil collected from the region. Two types of water were tested a blend of reclaimed water and filtered wastewater laced with bacteriophage, which is a type of virus that infects only bacteria. A bacteriophage is often used in studies as a substitute for human viruses, Di Giovanni said. The water was dripped under the soil surface in plastic columns built for the test. The research found that bacteriophage could be found on the crusty surfaces of both soil types and remained in the clay soil for about a month after irrigation ended.

"That suggests that human viruses could also linger in the soil," Di Giovanni said. "Reclaimed water must be effectively treated to remove or kill pathogens before use, regardless of irrigation method."

Finding such uses for reclaimed water is vital, said Experiment Station wastewater researcher Dr. Naomi Assadian.

"Wastewater reuse for agriculture and managed landscapes will be necessary to meet growing water demands and conser
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Contact: Kathleen Phillips
ka-phillips@tamu.edu
979-845-2872
Texas A&M University - Agricultural Communications
9-Aug-2005