In situ immobilization of lead from aqueous solutions and contaminated soils by phosphate rocks
- Pacific Northwest National Lab., Richland, WA (United States); and others
This study investigated and demonstrated that dissolved lead (Pb) from aqueous solutions and contaminated soils can be effectively immobilized under a wide range of pH conditions using a natural phosphate rock (PR) from North Carolina, USA. As little as 2% PR added can significantly reduce the Pb concentrations in the leachates of a contaminated soil to below the Toxicity Characteristic Leaching Procedure (TCLP) maximum allowable level or drinking water standard, depending on leaching solution pH. Lead immobilization occurs primarily when PR dissolves, and pyromorphite-type minerals precipitate under acidic conditions, or hydrocerussite precipitates under alkaline conditions. The pyromorphite-type minerals are highly leach-resistant under different pH conditions. These results, along with the ready availability and low cost of PR, imply that this technology could be a cost-effective option in the remediation of metal-contaminated soils, wastes, and groundwater. Current and developing emplacement methods will put this technology into practice.
- DOE Contract Number:
- FG06-92RL12451; AC06-76RL01830
- OSTI ID:
- 476031
- Report Number(s):
- CONF-960804--Vol.2
- Country of Publication:
- United States
- Language:
- English
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