Anaerobic/aerobic decontamination of DDT contaminated soil by repeated anaerobic/aerobic treatments
AssigneeZeneca Limited
InventorsRoger L. Bernier, Neil C. C. Gray, Ann L. Gray
Life of this patent
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Abstract
The present invention provides a process of decontaminating soil and/or sediments containing DDT type contaminants by converting these contaminants into harmless materials thereby decontaminating the soil to whatever extent desired, either partial decontamination or complete remediation.
Claims12
The process of decontaminating soil containing DDT-type contaminants which soil contains a population of viable anaerobic and aerobic microbes capable of transforming DDT-type contaminants into harmless materials and being viable under both anaerobic and aerobic conditions comprising:
- a) forming a degradation zone comprising said soil;
- b) maintaining said degradation zone at a temperature in the range of about 15.degree. C. to 37.degree. C., and maintaining in said degradation zone microbial population counts of at least 10.sup.5 cfu/g anaerobic and aerobic bacteria;
- c) supersaturating said degradation zone with water;
- d) rendering said degradation zone anaerobic;
- e) maintaining said degradation zone supersaturated with water and at a redox potential level below about negative 200 mV until a significant amount of DDT type contaminants is degraded;
- f) thereafter oxygenating said degradation zone to render it aerobic;
- g) maintaining said degradation zone at a redox potential level above about positive 100 mV until a significant amount of DDT type contaminants is degraded;
- and
- h) repeating steps c) through g).
The process of decontaminating soil containing DDT-type contaminants which soil contains a population of viable anaerobic and aerobic microbes capable of transforming DDT-type contaminants into harmless materials and being viable under both anaerobic and aerobic conditions comprising:
- a) forming a degradation zone comprising said soil;
- b) maintaining said degradation zone at a temperature in the range of about 15.degree. C. to 37.degree. C., and maintaining in said degradation zone microbial population counts of at least 10.sup.5 cfu/g anaerobic and aerobic bacteria;
- c) supersaturating said degradation zone with water;
- d) rendering said degradation zone anaerobic;
- e) maintaining said degradation zone supersaturated with water and at a redox potential level below about negative 200 mV until a significant amount of DDT type contaminants is degraded;
- f) thereafter oxygenating said degradation zone to render it aerobic;
- g) maintaining said degradation zone at a redox potential level above about positive 100 mV until a significant amount of DDT type contaminants is degraded;
- h) continually feeding water onto the top of said degradation zone and removing leachate from below said degradation zone while said degradation is anaerobic and aerobic;
- and
- i) repeating steps c) through g).
Dependencies are inferred from the claim text.