Scrubber (gas scrubber), Filter (gas filter). The flue gas is cleaned and cooled by the scrubber tower. A floor scrubber is a floor cleaning device. A venturi scrubber is a converging/diverging section of duct. Activated carbon can be used as a carbon dioxide scrubber. Emissions from spray dryers are typically controlled by a cyclone followed by a wet scrubber. Carbon dioxide is removed from the chamber gas by recycling it through scrubber cartridges. As it absorbs carbon dioxide in a rebreather's scrubber it emits oxygen. Another modification can be seen in the venturi-rod or rod deck scrubber. Some hobbyists use an algae scrubber to filter the water naturally. In addition, before the scrubber, straw and stones separators are installed. The removal of tar is often accomplished by using a water scrubber. A spray tower is the simplest type of scrubber. Water in the loop can greatly increase the resistance to gas flow through the scrubber. The hot gas enters the scrubber at the bottom.