In the treatment of industrial waste gas, the spray tower sucks the collected waste gas into the washing tower through a fan unit, flows through the filling layer section (the medium for gas/liquid contact reaction), and allows the waste gas to fully contact the liquid (washing solution) flowing on the surface of the filling material to adsorb acidic or alkaline pollutants contained in the waste gas. Then, the clean gas is separated from the contaminated liquid to achieve the purpose of purifying the air.