Submitted to: Proceedings of US EPA Silesia Soil Remediation Workshop
Publication Type: Proceedings
Publication Acceptance Date: 10/1/1999
Publication Date: N/A
Interpretive Summary: This paper reviews the development of Tailor-Made Biosolids Mixtures to remediate Pb-contaminated urban soils, and hazardous metal contaminated Superfund sites. Based on greenhouse and laboratory studies, a field test was conducted at a Zn-smelter contaminated site where plants were killed by soil Zn and other metals. Other laboratory and feeding studies showed that this same method can reduce the bioavailability of soil Pb. Such a method is needed for the Pb contaminated soils in cities where paint-Pb and auto exhaust-Pb built up in soils around houses. Houseside soil Pb can reach as high as 5% of dry soil. These urban soils are not remediated by Superfund, the program to remediate hazardous soils. Because biosolids composts can be used as fertilizer or soil conditioner in areas where children could be exposed to the amended soil, these materials could be used to reduce the risk to children of soil Pb. High Fe and phosphate provide effective precipitation and adsorption of Pb even in the intestine based on our soil feeding tests of soil Pb bioavailability. At the same time, the high Fe and P contribute to remediation of Zn-Cd-Pb toxicity in smelter contaminated ecosystems and mine wastes if soil pH is made calcareous by addition of a large rate of limestone equivalent. Although the Tailor-Made Mixtures can be made from livestock manures and many other agricultural, municipal and industrial byproducts, when high Fe biosolids composts are produced in a city, this material is especially effective in inexpensive yet persistent remediation of soil metal risks. Mixing with limestone or lime equivalent rich byproduct gives a complete remediation amendment ready for use.
Technical Abstract: Paper reviews modern risk assessment for soil metals, and beneficial use of biosolids to remediate Zn-Pb-Cd contaminated mine wastes and smelter contaminated soils in the vicinity of Katowice, Poland. Our research on beneficial use of biosolids has been shown in laboratory and field studies that amendment of urban soils can reduce plant uptake of soil Pb and the bioavailability of Pb in ingested soil. Similar remediation is achieved by biosolids plus limestone at Zn and Cd contaminated soils. Further, by combining other byproducts of agriculture, industry and urban industries with biosolids, and processing to fit the end use, we have illustrated the use of "Tailor-Made Biosolids Mixtures" to inactivate soil Pb, Zn and Cd and and remediate dead soils. High Fe, P, and fertility of biosolids amended soils aid in precipitation and adsorption of soil Pb, and adsorption of soil Cd, Zn, and other elements. In the case of Pb, we have conducted soil feeding tests to measure the effectiveness of biosolids constituents and processing on bioavailability of Pb in the amended soils. For urban soils from Baltimore, bioavailability of Pb has been reduced by as much as 60% at 30 days after adding 224 t/ha of high Fe biosolids or composted biosolids. Part of this reduction in bioavailability is due to the formation of chloropyromorphite, a very insoluble Pb mineral. In cooperation with EPA's Superfund Emergency Response Team, we have successfully illustrated use of mixtures of biosolids with alkaline byproducts (wood ash; coal ash; limes) and wood byproducts, for revegetation of Superfund sites at Palmerton, PA, Kellogg, ID; Leadville, CO; and Joplin, MO.