Model Development and Simula- Tion of in Situ Stabilization in Lead-contaminated Soils

370 MODEL DEVELOPMENT AND SIMULATION OF IN SITU STABILIZATION IN LEAD-CONTAMINATED SOILS Z. Shi and L.E. Erickson 105 Durland Hall, Department of Chemical Engineering, Kansas State University, Manhattan, KS 66506; Phone: (785) 532-4323, Email: [email protected]; Phone: (785) 532-4313, Email: [email protected] ABSTRACT Stabilization and remediation of lead-contaminated soils have received considerable attention recently. Amending Pb-contaminated soils with phosphate as an in situ remediation option has been proposed as an alternative to other remediation options such as soil removal. Research shows that hydroxyapatite (HA) [Ca 5 (PO 4 ) 3 OH] can reduce the bioavailability of Pb efficiently and thus is considered as an ideal phosphate source for formation of lead pyromorphite. Environmental models are increasingly being relied upon to help identify the limiting factors in such kind of in situ remediation. In the present work, models which include adsorption, diffusion, and reaction have been developed to describe the transformation of lead contaminants to pyromorphite in single particles, aggregates, and soil beds, respectively. Principal factors controlling the time of remediation have been identified. The contaminated aggregates remediation model has been developed and simulated to describe the effect of initial contaminant concentration, diffusion coefficient, and aggregate diameter on the time of remediation.