Venturi washers are used to remove solid particles from gas emissions by using a liquid flow. Their performance is based on
mechanisms of impact and absorption by tangential contact of dust particles with water droplets. In the venture washers, gas-containing particles passes through a small tube which the middle of it is narrow and its end is broad. This contraction causes the gas flow rate to increase as the pressure increases. The difference in the speed and pressure after the contraction causes the particles and water to be mixed and combined together. The slowdown in the expansion part of the orifice allows the water droplets containing particles to remove from the gas stream. Venturi washers are useful for separation of small particles with high separation efficiency of 99%. One of the drawbacks of this system is to produce wastewater.