HEAVY METAL REMEDIATION OF SOIL USING PERMEABLE CHELATION BARRIERS

REMEDIATION OF SOIL AND GROUNDWATER TO REDUCE HEAVY METAL CONTAMINANTS TO BACKGROUND LEVELS POSES A SERIOUS CHALLENGE. CONVENTIONAL METHODS ARE ABLE TO REDUCE CONTAMINATION LEVELS, BUT TOTAL REMEDIATION, DEFINED AS ACHIEVEMENT OF BACKGROUND LEVELS OF THE METAL, MAY NOT BE ECONOMICALLY FEASIBLE. A PERMEABLE CHELATION BARRIER CONTAINING SILICA GEL MODIFIED TO CHELATE HEAVY METALS PROVIDES AN ECONOMICAL METHOD TO ATTAIN COMPLETE REMEDIATION OF CONTAMINATED SOILS. SILICA GEL WILL BE MODIFIED BY ATTACHMENT OF AMINE, POLYAMINE, OR POLYAMINE POLYCARBOXYLATE GROUPS, YIELDING A SOLID MATERIAL CAPABLE OF BINDING IONS OF HEAVY METALS INCLUDING LEAD, CHROMIUM, CADMIUM, AND URANIUM. THE CHELATING GEL THEN IS CONTAINED IN A PERMEABLE FABRIC, AND PLACED IN A TRENCH SURROUNDING MODERATELY CONTAMINATED SOIL, WHERE IT FUNCTIONS WITH MINIMAL MAINTENANCE, REQUIRING ONLY PERIODIC MONITORING OF METAL CONCENTRATION. WHEN METAL CAPACITY IS ACHIEVED, THE BARRIER IS REMOVED AND REGENERATED FOR FURTHER USE. IN PHASE I SUCH CHELATING SILICA GELS CONTAINING AMINE, POLYAMINE, AND POLYAMINE POLYCARBOXYLATE GROUPS WILL BE SYNTHESIZED. THE METAL CAPACITY OF THE GELS WILL BE MEASURED, AND EASE OF REGENERATION DETERMINED. RECOVERY OF THE METALS WILL BE EVALUATED. USE OF SILICA GELS IN PERMEABLE CHELATION BARRIERS WILL BE EXPANDED TO SOIL REMEDIATION IN PHASE II ACTIVITIES. THE BENEFITS OF THIS TECHNOLOGY INCLUDE TOTAL REMEDIATION OF METAL CONTAMINATED SOILS AND PROTECTION OF SENSITIVE WATER SOURCES WITHOUT A LABOR-INTENSIVE INTERVENTION. IN THIS WAY, PARTIAL REMEDIATION CAN BE ACCOMPLISHED IN A COST-EFFECTIVE MANNER RESULTING IN REDUCTION OF HAZARDOUS METALS TO BACKGROUND LEVELS.