TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Component: Each rotary shaft of the reactor is structured with pallet-shaped stirrers for carrying out a homogeneous stirring of the solid, the liquid and the gaseous phases. The pallet stirrers are removable by employing mechanical couplings to the rotary cylinder-shaped structure. The plant is supported onto wheeled motor vehicles in order to be hauled to sites having soils requiring depollution from heavy metal compounds.    TECHNOLOGY FOCUS - ENVIRONMENT - Preferred Method: Liquids consisting of water and/or sugary solution are added by percolation techniques and are removed by filtering or draining.Preferred Condition: The treatment is carried out for 7-14 days. The edible materials are steam sterilized at 100-180, preferably 100-130 degrees C. The dry weight ratio between the edible materials and the molasses is 1:0.5-1:1.5. The total amount of the edible materials are equally subdivided in three fractions and applied in three quantities during the treatment. The molasses is used as a water-diluted solution at a 150 g/L concentration. The molasses solution is percolated through the soil at 100 ml/h per kilogram of soil, periodically every 90 minutes. Air is injected and/or vacuum is applied intermittently to remove the liquids from the soil and to aerate the soil. The percolation is performed for 10-16 hours during a day of treatment. At the end of percolation, the soil is washed out with water or with 0.01 M calcium chloride (CaCl2) solution at up to 800 ml/kg of soil.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Material: The edible materials consist of cereals and/or fruit peels (e.g., apple and citrus peels). The substances contained in the sugary solution are sugar mill wastes. The sugary substances consist of glucose syrup, molasses or their mixture containing greater than 20 (preferably greater than 40) weight% glucose.    TECHNOLOGY FOCUS - BIOLOGY - Preferred Microorganism: The microorganisms are fungi of the genera Penicillium and Aspergillus.