water treatment residuals have a high ability to bind phosphorus because they
contain high concentrations of aluminum oxide and hydroxide
groups. Click the image for more information about it.
in the magazine.
Water-Treatment Residues Curb Phosphorus
Runoff By Luis
July 8, 2004
Residue from water-treatment plants, often discarded as waste
into landfills, may make good soil treatments for preventing phosphorus runoff
Service soil scientist Jeffrey M. Novak at the agency's
Coastal Plains Soil, Water and
Plant Research Center in Florence, S.C., is studying an alum-based
water-treatment residual that increases soil's capacity to bond phosphorus, a
vital plant nutrient.
The studies, done in collaboration with Ray Bryant, research
leader at the ARS Pasture Systems and
Watershed Management Research Unit in University Park, Pa., may benefit
states along the nation's mid- to-southern-Atlantic seaboard, where sandy soils
generally take up and hold less phosphorus than finer-textured soils.
Increased bonding, or adsorption, of phosphorus would curb
runoff of this nutrient that can lower the oxygen content of water bodies and
spoil the taste of drinking water. Phosphorus in manure makes agricultural
facilities, such as large livestock production operations, potential sources of
According to Novak, chemically binding phosphorus into
water-insoluble complexes using residuals containing iron oxide, aluminum oxide
and hydroxide may become an important management practice. The alum-based
water-treatment residual this research focuses on has a high phosphorus-binding
A separate study, conducted on wheat by agronomist Eton Codling
at the ARS Animal
Manure and Byproducts Laboratory in Beltsville, Md., found that the
treatment has no negative effect on plants' absorption of phosphorus once plant
roots grow beyond the 6-inch-deep layer the treatment creates in soil.
In lab tests with sandy soil, the treatment increased
phosphorus-binding potential four- to fivefold over that of untreated soil. The
lab studies will be repeated, and additional research will be done in the field
during the next two years. If successful, this use for waste from
water-treatment processing not only could get rid of the waste, but would also
hold phosphorus on the land until a crop uses it.
about this research in the June issue of
ARS is the U.S. Department of
Agriculture's chief scientific research agency.