Sludge - a resource whose time has come
Sewage composition, median figures based on samples collected from 200 different sources in eight states, consists of organic carbon, 30%; total nitrogen, 3.3; total phosphorus, 2.3; total sulfur, 1.1; calcium, 3.9; iron, 1.1; aluminum, 0.4; sodium, 0.2; potassium, 0.3; and magnesium 0.4. In ten years of experiments, Dowdy and his ARS and University of Minnesota colleagues found sludge supplied all the nitrogen and phosphorus that crops could use, but additional potassium was needed. They successfully grew corn, potatoes, green beans, and other vegetables, as well as turfgrasses. The contents of sludge if applied at the rate plants normally use nutrients, are either beneficial or harmless to plants. Public concern is with trace metals, Pb, Hg, Cd, M, Zn, and Cu. Lead and Hg normally in sewage sludge are not available for plant uptake. Zinc, nickel, and copper are not a problem in animal or human food, because plants will stop growing before they can accumulate enough metal to be harmful to animals or people consuming them. Cadmium is taken up by plants, under acid soil conditions. To evaluate the effects of high cadmium feed on livestock, the researchers compared corn silage treated with commercial fertilizer and silage grown on land receiving annual application as high as 20 tons of high Cd sludge an acre. The highest rate of sludge application produced silage containing 5.26 ppM of Cd. This was fed to lambs and dairy goats. Cadmium concentration in goat's milk, did not increase as result of eating the silage. However, cadmium concentration did increase in the kidney and liver tissue of both goats and lambs. Soil acidity is the major soil characteristic that affects trace metal uptake by growing plants. Where soil acidity is maintained at a pH value of about 6.5, only a small percentage of sludge-borne metals will be absorbed by a given crop and they will not leach into groundwater.
- Research Organization:
- Univ. of Minnesota
- OSTI ID:
- 5749669
- Journal Information:
- Agric. Res.; (United States), Journal Name: Agric. Res.; (United States)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Cadmium and zinc availability to corn following termination of sewage sludge applications
Heavy metals application and plant uptake in a land disposal system for waste water
Related Subjects
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
54 ENVIRONMENTAL SCIENCES
CADMIUM
TOXICITY
SEWAGE SLUDGE
BIOLOGICAL EFFECTS
WASTE PRODUCT UTILIZATION
ALUMINIUM
BEANS
BIOLOGICAL ACCUMULATION
CALCIUM
CARBON
CHEMICAL COMPOSITION
COPPER
GOATS
GROUND DISPOSAL
IRON
LAND POLLUTION
LEAD
MAGNESIUM
MAIZE
MERCURY
NICKEL
NITROGEN
PH VALUE
PHOSPHORUS
PLANT GROWTH
POTASSIUM
POTATOES
SHEEP
SODIUM
SOILS
SULFUR
ZINC
ALKALI METALS
ALKALINE EARTH METALS
ANIMALS
CEREALS
DOMESTIC ANIMALS
ELEMENTS
FOOD
GRASS
GROWTH
MAMMALS
MANAGEMENT
METALS
NONMETALS
PLANTS
POLLUTION
RUMINANTS
SEWAGE
SLUDGES
TRANSITION ELEMENTS
TUBERS
VEGETABLES
VERTEBRATES
WASTE DISPOSAL
WASTE MANAGEMENT
WASTES
140504* - Solar Energy Conversion- Biomass Production & Conversion- (-1989)
560303 - Chemicals Metabolism & Toxicology- Plants- (-1987)
560305 - Chemicals Metabolism & Toxicology- Vertebrates- (-1987)
510200 - Environment
Terrestrial- Chemicals Monitoring & Transport- (-1989)