Abstract: The invention relates to an absorption tower (so-called scrubber) for gas washing in which the gas is introduced into the lower portion of the tower and flows upwards while making contact with a washing fluid. The tower (4) is provided with one or several washing stages (6-9), each comprising one or several venturi tubes (10) through which the gas is given a speed increase and the washing fluid is discharged through fluid nozzles (25) in the gas flow path. The venturi tubes in each washing stage are led through a common collecting baffle (11) for washing fluid which is then recirculated to the nozzles. Means (26,28,29) for liquid distribution are disposed in the upper portion of each venturi tube (10) and are arranged for fluid distribution in the gas flow in directions forming such angles to the vertical that the fluid flow will not fall backwards into the openings of the venturi tubes even if the gas flow through the tower is interrupted.

Abstract: In a plant for purifying contaminated air, the contaminants are transferred from the air to a liquid flowing through a spray booth through which the contaminated air also flows in intimate contact with the liquid. The liquid is then collected in a container, from which it is recirculated to the spray booth. The closed liquid circulation circuit in flow communication with the spray booth is connected to a biological cleaning step in which the contaminants dissolved and/or suspended in the liquid are decomposed and then separated. The biological cleaning step comprises a bioreactor in which the main portion of the bio-degradation occurs, and a separator, for separation of the biosludge coming from the reactor. At least part of the contaminated liquid passing through the spray booth is continuously transferred to the biological cleaning stage from which substantially the same quantity of the cleaned liquid is recirculated to the spray booth circulation circuit.