A Wet Scrubber is an air pollution control device that uses a liquid to remove contaminants from a gas stream. The removal process is achieved by bringing the gas stream into contact with the scrubbing liquid, which facilitates the mass transfer of contaminants into the liquid. When the water is recirculated, the addition of fresh water is necessary to purge contaminants and replace evaporation losses. Fresh water may be added to the recycling continuously or periodically. Wet scrubbers remove dust particles by capturing them in liquid droplets. The droplets are then collected, the liquid dissolving or absorbing the pollutant gases. Any droplets that are in the scrubber inlet gas must be separated from the outlet gas stream by means of another device referred to as a mist eliminator or entrainment separator (these terms are interchangeable). Also, the resultant scrubbing liquid must be treated prior to any ultimate discharge or reused in the plant.