Wet

The wet process consists of cooling down the flue gas below the dew point to condense acidic gases and neutralizing it using a liquor of a certain pH. This pH is controlled using either milk of lime or a suspension of calcium carbonate (milled limestone).

A filter (often an electro-filter) is normally added upstream to the wet scrubber in order to remove the fly ash.
 

Valorisation

The liquid effluent is treated downstream in a waste water treatment plant in order to produce high quality gypsum used in the building industry.

This process enables a very favorable energy recovery  the use of a heat exchanger before the scrubber.

Wet scrubbers are usually designed for large installations, e.g. coal-fired power plants.