wet scrubbers (wet scrubber system)
Also known as: scrubbing liquid treatment · wet gas scrubber
Wet scrubbers are air pollution control devices that remove particulate matter and gaseous pollutants from industrial exhaust streams by bringing contaminated gases into contact with a scrubbing liquid, typically water.
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What is wet scrubbers?
What it is
Wet scrubbers are a type of air pollution control device used in industrial settings to remove particulate matter and gaseous pollutants from exhaust streams. They operate by bringing the contaminated gas stream into contact with a scrubbing liquid, typically water, to absorb or physically remove pollutants [3].
How it works
The basic principle involves passing the exhaust gas through a chamber where it is sprayed with or bubbled through a scrubbing liquid. Pollutants are transferred from the gas phase to the liquid phase through various mechanisms. For gaseous pollutants like sulfur dioxide (SO2), the scrubbing liquid chemically reacts with or dissolves the gas [3]. For particulate matter, the liquid droplets or film capture the particles through impaction, interception, or diffusion. The contaminated scrubbing liquid is then collected and treated, while the cleaned gas is released. The efficiency of wet scrubbers can be limited by the solubility of certain compounds in the scrubbing liquid, such as calcium salts, which can lead to scaling and reduce operational effectiveness [3].
Operational realities and downsides
While effective for certain pollutants, wet scrubbers have limitations. Their efficiency in reducing the environmental impact of fine particles, particularly those in the 60–200 nm range, can be minimal, with particles passing through largely unchanged chemically, except for sulfate uptake [1]. This means that despite reducing overall emissions, the health and environmental impacts of the remaining emitted particles may not be significantly mitigated [1]. Furthermore, the infrastructure and consumables required for wet scrubber operation, including energy and water, contribute to their overall environmental footprint. There can be trade-offs between emissions reduction and increased resource consumption [2]. Poor performance can also occur, particularly with specific volatile organic compounds (VOCs), leading to breakthrough and odour issues [4]. Maintaining efficiency requires managing issues like scale formation, which can cause plant downtime [3].
wet scrubbers across recycling sectors
How this plays out in practice, sector by sector.
Role in plastic chemical recycling and pyrolysis
In plastic chemical recycling and pyrolysis operations, wet scrubbers are employed primarily to manage emissions from the thermal decomposition processes. These processes can generate a range of gaseous pollutants, including volatile organic compounds (VOCs), particulate matter, and acidic gases, which require treatment before discharge. Wet scrubbers help in capturing these pollutants, contributing to compliance with air quality regulations.
Economic and operational considerations
The economics of integrating wet scrubbers into plastic chemical recycling and pyrolysis facilities involve capital expenditure for installation and ongoing operational costs. These include energy consumption for pumps and fans, water usage, and the cost of any chemical additives for the scrubbing liquid. Additionally, there are costs associated with treating and disposing of the contaminated scrubbing liquid, which can contain dissolved pollutants and particulate matter. The effectiveness of wet scrubbers can vary depending on the specific composition of the exhaust gases, with some VOCs proving difficult to remove, leading to odour issues and potential regulatory challenges [4]. While they can reduce certain air pollutants, the trade-offs between emission reduction and increased energy and resource consumption need careful evaluation [2]. The need for regular maintenance to prevent issues like scaling further adds to operational expenses and can lead to downtime [3].
Common questions about wet scrubbers
Plain-English answers to what people most often ask.
Are wet scrubbers effective for all types of emissions from plastic pyrolysis?
How do wet scrubbers affect the operational costs of a pyrolysis plant?
Do wet scrubbers completely eliminate harmful particles from exhaust gases?
Citations & references
Peer-reviewed and published sources underpinning this entry. Numbered markers [n] in the text above link here.
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1
Limited efficiency of wet scrubbers in reducing the environmental impact of ship-emitted particles
Lukas Anders et al. · 2025
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2
Air treatment technologies in pig farms. Life cycle assessment of dry and wet scrubbers in Northern Italy and Northeastern Spain.
Marta Ruiz-Colmenero et al. · 2024
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3
Scale formation in wet scrubbers and the current state of anti-scaling and softening methods for hard waters: A review
Thandiwe Fungene et al. · 2023
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4
Performance of wet scrubbers to remove VOCs from rubber emissions.
N. Idris et al. · 2022
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6
Potential Use of Wet Scrubbers for the Removal of Tobacco Dust Particles in the Tobacco Industry
Xinli Zhao et al. · 2022
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