High-efficiency processes for destruction of contaminants

Abstract

The present invention relates to novel ex situ processes for simple and economical destruction of air, water, and soil contaminants using naturally occurring microorganisms that are widely available in the environment. The processes utilize novel closed-loop recycle schemes which dramatically improve the efficiency, economics, and practicability of destruction of a wide variety of contaminants, especially VOCs and chloroethylenes, and particularly trichloroethylene (TCE). The processes may be applied on a batch or continuous basis to contaminated soil and groundwater, to contaminated effluents from a wide variety industrial operations, or to wherever such amenable contaminants are present. Certain contaminants, particularly chloroethylenes, are known to be difficult to biodegrade aerobically to non-toxic products without the employment of a primary substrate to induce cometabolic degradation. Ordinarily, practical and economical cometabolic degradation of these compounds via a primary substrate is not possible because direct metabolic degradation of the primary substrate itself competes with degradation of the target pollutants, thus rendering degradation of the target pollutants economically prohibitive. The processes of the present invention utilize novel closed-loop recycle schemes and separate primary substrate streams and contaminant streams into separate and discrete process cycles to achieve simple, practical, and economical degradation of target pollutants. Conventional wisdom indicates that these closed-loop recycle schemes should deplete the oxygen supply, causing loss of the aerobic microorganisms and process failure. However, the novel closed-loop recycle schemes of the present invention unexpectedly result in dramatically improved efficiencies and economics for degradation of a wide variety of pollutants, particularly chloroethylenes.