scrubbers

Scrubbers are air pollution control devices that remove pollutants from exhaust streams by bringing the gas into contact with a liquid or solid absorbent. They are used to treat industrial flue gases, process emissions, and ship exhaust to meet environmental standards.

Wet scrubbers use liquid media such as water or chemical solutions to dissolve or react with contaminants. Common configurations include spray towers, venturi scrubbers, and packed-bed towers. They can remove sulfur oxides, hydrogen chloride, ammonia, and particulates, with efficiency depending on gas flow, contact time, and absorbent chemistry.

Dry scrubbers inject dry sorbents such as lime or sodium bicarbonate and rely on chemical reactions to neutralize pollutants, often producing a dry or partly dry byproduct. Spray-dryer absorbers and circulating dry scrubbers are used for sulfur dioxide control and other acid gases.

Biological scrubbers, including biofilters and biotrickling filters, use moisture and microorganisms to degrade volatile organic compounds and some odors, typically in air treatment for low concentrations.

Industries such as power generation, cement manufacturing, metal processing, and ship propulsion employ scrubbers to reduce emissions. Marine exhaust gas cleaning systems are used to meet sulfur cap regulations; they can be open-loop or closed-loop, each with environmental tradeoffs.

Operational considerations include water or reagent management, byproduct handling (sludge or gypsum), corrosion, energy use, and maintenance. Scrubbers shift emissions from air to liquid waste streams, requiring permits and wastewater treatment to minimize disposal impacts.