Biological cleaning of contaminated soil - by mixing soil with water and microorganism(s) in rotating aerator reactor vessel which allows large quantities of soil to be cleaned

摘要

Sterilising contaminated soils comprises excavating, pulverising, homogenising and then biologically treating soil in a reactor vessel. The process is modified by mixing the soil with a liq. pref. water, to form a sludge with a moisture content of about 40 to about 80%, mixing it in the reactor vessel, and adding at least one oxidn. agent. The sludge is held in the reactor at a temp. of about 25 to 70 deg.C, and air, oxygen or hydrogen peroxide may be used as the oxidn. agent. Nutrients for the biomass are added to the sludge. The material in the reactor is held at a pH value of about 5.5 to about 8.5. In a subsequent sepn. stage, the liq. is sepd. into a liq. and biomass on one hand, and decontaminated soil on the other hand; the liquid and biomass are recirculated to the reactor vessel while the decontaminated soil is removed. Gas evolved in the reactor is removed and cleansed in a biofilter.