Experimental Study of Heavy Metals Distribution, Attenuation and Mobility inTwo Oklahoma Soils Amended with Sewage Sludge.
Kefeni Kejela, USDA/NRCS, 1238 County Welfare Road, Leesport, PA 19533 and Dee Ann Sanders, Associate Professor, School of Civil and Environmental Engineering, Oklahoma State Univ, 207 Engineering South, Stillwater, OK 74078.
Land application of sewage sludge (Biosolids) remains one of the viable methods of waste management practices. An important task in waste disposal should be adequate evaluation of the confinement and the rate of movement of pollutants from the source of contamination. Also, precise information on the leaching of pollutants such as heavy metals is needed to establish a base for evaluating waste disposal systems. Caution is appropriate for sewage sludge because heavy metal, unlike any pollutants, cannot degrade and therefore, can retain in soils virtually indefinitely. As a result, there is a little opportunity for natural recovery from the consequences of any error in judgment. Proper management of sewage sludge is necessary not only for our well fare, but also for the well being of future generation to come. The specific objectives of this study are (a) To provide information on leaching mechanism and attenuation of heavy metals (Zinc, Nickel and Chromium) on two different soil types (sandy and Clay) (b) To provide a base for developing pollution control procedures and guide lines regarding land application of sewage sludge. Two soil types, 3 soil horizons three treatments and three replications were used for the study of this experiment. 18 PVC pipes (4 inches diameter) for laboratory based soil column leaching were used. Soil Sequential Extraction Method is used to fractionate heavy metals into residual, organic, carbonate, exchangeable forms. The study showed that the soil properties most useful in predicting mobility of zinc, nickel and chromium were Soil texture, Organic matter, Iron oxides and soil pH. The most mobile heavy metals were zinc and nickel, and the least mobile was chromium.