Phosphate - Induced Metal Stabilization

EPA Contract Number: 68D60023
Title: Phosphate - Induced Metal Stabilization
Investigators: Conca, James
Small Business: NW Environmental Services - Testing and Training
EPA Contact: Manager, SBIR Program
Phase: I
Project Period: September 1, 1996 through March 1, 1997
Project Amount: $66,307
RFA: Small Business Innovation Research (SBIR) - Phase I (1996) RFA Text |  Recipients Lists
Research Category: Small Business Innovation Research (SBIR)


The problem addressed by this proposal is the need to remediate heavy metals in groundwater and soils. The proposed method can immobilize metals by chemically binding them into extremely stable phosphate phases (apatite minerals) in the soil, sediment, or in a permeable reactive barrier. The stabilization is irreversible under most environmental conditions for hundreds of millions of years, (e.g., pH 2 to 12 up to 1000?C, in the presence of aqueous and non-aqueous phase liquids, and under disruptions such as earthquakes, ground subsidence or human intrusion). Also, because of this extreme stability, the effects of soil heterogeneity, hydrology and other subsurface properties do not affect the performance, and, themselves, and not affected by this treatment. The objective of Phase I is to demonstrate that the apatite treatment of lead zinc and cadmium-contaminated soil and groundwater from the Bunker Hill Mining Site (EPA Region 10) will permanently immobilize the metals in new stabile mineral phases. The specific work consists of a series of soil column flow experiments using contaminated soils from the site which will be mixed with four different types of apatite in each fashion as would occur during either mixing (auguring) of soil in the field or emplacement of a permeable reactive groundwater barrier. Actual groundwater will be applied to the top of the columns. Leachates will be collected every 24 hrs. until "breakthrough". This will provide the loading capacity for each type of apatite as demonstration of effectiveness of each type of apatite. Together with batch tests, geochemical modeling and choice of emplacement methods, these tests will determine the feasibility of the Phase II field work. Effectiveness and cost will determine the final choice of apatite for Phase II. The success of this work should have immediate benefit for almost all metal-contaminated sites.

Supplemental Keywords:

small business, SBIR, engineering, chemistry, hazardous waste., Scientific Discipline, Toxics, Geographic Area, Waste, Water, Chemical Engineering, Contaminated Sediments, Environmental Chemistry, Chemistry, Engineering, Groundwater remediation, 33/50, Environmental Engineering, EPA Region, aquatic ecosystem, sediment treatment, cadmium & cadmium compounds, metal stabilization, lead, lead & lead compounds, contaminated sediment, chemical contaminants, geochemical modeling, Zinc, heavy metal contamination, apatite treatment, cadmium, Region 10, heavy metals

Progress and Final Reports:

  • Final