Biofilm Remediation for Restoration of Contaminated Army Sites

Free-phase pollutants are persistent environmental contaminants. Present in situ remediation involving biological/chemical oxidation of trichloroehylene (TCE), perchloroethylene (PCE) and explosives [2,4,6-trinitrotoluene (TNT),hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX)] is limited to diluted plumes. Physical and mechanical removal of free-phase pollutants results in the generation of air pollutants and contaminant spreading.An enhanced process of in situ free-phase pollutant removal by indigenous micro-organisms that are pre-adapted for metabolizing the pollutants on the pollutant free-phase surface is proposed. The micro-organisms will have a high affinity to the pollutantfree-phase because of their increased hydrophobicity. This will drive the degrading micro-organisms towards the sites where the free-phase pollutants are localized, fix them to the sites, thereby assuring the long-term stability of the formed biofilms.The contaminants will be continuously degraded by the biofilm. When formed, the biofilm will also prevent further mobilization of pollutants in the environment.An advanced continuous selection process will achieve the desired hydrophobicity of the microbial surface. Selective pressures for this system are the availability of pollutants, as the phase separated carbon source, and an antibiotic, causing desiredchanges in cell hydrophobicity. The pre-adapted microorganisms will be returned to their native environments and form/participate in the pollutant-degrading biofilms. Additional nutrients will be required. (P-010749) In situ biological remediation is preferred to ex situ treatment because of lower energy and capital investment costs, it is more efficient due to immediate localization of the polluted area, and the aquifers can be completely restored.This development, if successful, will provide a unique opportunity for removing the source of extensive environmental contamination, namely pools of chlorinated solvents and solid residues of explosives. This process can be used not only by the USDepartment of Defense, but also by commercial firms both in the United States and abroad.