Sand bed downdraft furnace and activated carbon scrubber

A device for the roasting of spent activated carbon, waste sludges, or other organic wastes, comprising:

• a downdraft bed furnace at the head or feed end of the system;
• a first adsorber unit fluidly coupled to the furnace and including a closed tank of adsorber process solution, with a venturi scrubber and a cyclone separator coupled to the tank such that gases are sucked into the venturi then through the cyclone separator, the liquid effluents from the scrubber and separator falling by gravity into the tank;
• a second adsorber unit fluidly coupled to the first adsorber unit and including a closed tank of adsorber liquid, with a venturi scrubber and a cyclone separator coupled to the tank such that gases are sucked into the venturi then through the cyclone separator, the liquid effluents from the scrubber and separator falling by gravity into the tank, the second adsorber unit configured to remove impurities not removed in the first unit;
• and
• an exhaust fan or blower fluidly coupled to the second adsorber unit and configured to pull air into the furnace, through the first and second adsorber units.