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Greater Harmony Between Agriculture and the Environment
Reclaiming Wastewater through Soil Aquifer Treatment
Issue
Water-short areas in the U.S. and around the world have turned to reclaiming
wastewater as a way to increase water supplies. Some treatment methods
use chemical additives to help purify the water. Charles Gerba, a University
of Arizona soil scientist, tested a more natural method currently used
in Tucson, and found that it produced high quality nonpotable water
without additives at a low cost.
What has been done?
The soil aquifer treatment used a 37-meter layer of soil as a filter.
Wastewater was purified as it passed through, and was then collected
in underground storage tanks. This is a natural, sustainable system
that will not wear out. It takes the place of building a conventional
treatment plant.
Impact
The soil aquifer treatment significantly reduced enteroviruses as they
passed through the soil. Groundwater samples held no Giardia. The two
organic compounds present were reduced by 92 percent and 85 percent
respectively, and total nitrogen leached out 47 percent during recharge.
The project has now expanded to include the City of Phoenix in Arizona,
and Los Angeles and Orange Counties in California, at the request of
those communities.
In Tucson, the project grew to include studies on using artificial
wetlands as a pretreatment before soil aquifer treatment. At Tucson’s
Sweetwater Wetland and Recharge Facility the wetlands method reduced
Giardia cysts and Cryptosporidium oocysts by more than 99.9 percent,
and fecal coliforms and coliphages by 68 and 52 percent, respectively.
Funding
City of Tucson, American Water Works Association Research Foundation
U.S. Environmental Protection Agency (EPA)
Los Angeles County Sanitation District
Agricultural Research Service
Contact
Charles Gerba, soil scientist
Department of Soil, Water and Environmental Science
Shantz Bldg., Room 429
PO Box 210038
The University of Arizona
Tucson, AZ 85721
Tel: (520) 621-6906, FAX: (520) 621-1647
Email: gerba@ag.arizona.edu
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