| abstract |
The invention relates to insitu bio-electrokinetic remediation of contaminated soil containing hazardous mixed wastes as organic pollutants and hazardous heavy metals. Bio-remediation of the organic pollutants is followed by removal of the hazardous material. Cultured micro-organisms, nutrients and growth factors are added to clean soil adjacent to contaminated soil. Positive anodes and negative cathodes are placed in the microbial-loaded clean soil adjacent to the contaminated soil. The negative cathode is closest to the interface of the clean and contaminated soil. DC current is applied between the electrodes and water containing cultured microorganisms is pushed by the electrokinetic pumping effect into the contaminated site. The acid generated at the anode is not allowed to enter the contaminated soil. Cultured microorganisms are introduced into clean soil on the opposite side of the contaminated soil. DC current is reversed to change the original anode to cathode and cathode to anode. Micro-organism laden water is pulled into the contaminated site. The push-pull current reversal process is repeated to increase insitu biodegradation efficiency. When the biological oxidation of organic pollutants is complete, the acid front enters the contaminated soil for removal of hazardous metals. Hazardous metals precipitate near or electroplate on the cathode or are recovered from fluid collected at the cathode. Solubilizing materials are added to the water near the cathode to minimize the precipitation reaction. Fluids collected at the cathode are pumped through a treatment system before water is returned to the soil. |