droplets are easily separated from the gas by gravity. The solid particles can then be independently separated from the water, or the water can be otherwise treated before reuse or discharge. Increasing the gas velocity or the liquid droplet velocity in a scrubber increases the efficiency because of the greater number of collisions per unit time. For the ultimate in wet scrubbing, where high collection efficiency is desired, Venturi scrubbers are used. These scrubbers operate at extremely high gas and liquid velocities with a very high-pressure drop across the Venturi throat. Venturi scrubbers
(see Figure 10.1) are most efficient for removing particulate matter in the size range of 0.5 to 5μm, which makes them especially effective for the removal of submicron particulates associated with smoke and fumes.