Industrial air filtration is concerned with achieving a specified level of particulate cleanliness, filtering fumes, vapours, gases and dust from industrial air to improve air quality in a system or working environment.

Industrial air is a by-product of industrial processes. For example, sawmills produce air contaminated with dust, and diesel generators produce air contaminated with CO2 and NOx. In a work environment, these emissions are dangerous, so they need to be controlled, and air filtration is how we achieve this.

Industrial air filtration systems

Industrial air filtration systems range from single-stage systems that take off-gases from machines and run them through a carbon filter to multi-stage treatments that take heavily saturated air and run it through biofilters and a dry scrubber.

Dry scrubbers

fume scrubber


Dry scrubbers are specified to scrub exhaust gases and fumes, offering a simplified solution to wet scrubb

ers because they produce no sludge. A dry scrubber will scrub VOCs, CO2, chlorine, chloramine, tannins, phenol, hydrogen sulphide and siloxanes.

In dry scrubbers, removal characteristics are defined by the media type. Activated carbon, impregnated carbon, oxidising alumina media or hybrid media can be specified to remove various contaminants, from aldehydes to oxidisable contaminants.

Dry scrubbers are suitable for fans, pumps, valve control systems, exhaust stacks, ductwork systems, pipework and vents.


Biofilters contain living microorganisms that consume biodegradable particulates, including hydrogen sulphide and ammonia. The microorganisms degrade contaminants into CO2, H2O, mineral salts and organic compounds for food.

In biofilters, removal characteristics are defined by the microbiology of the filter. Different types and quantities of bacteria are used to remove different particulates. Getting the biology right is crucial for the filter to work properly.

FGD Scrubbers

Flue gas desulphurisation (FGD) systems, also known as gas absorbers, remove sulphur dioxide (SO2) and hydrogen chloride (HCl) from flue gases.

These systems use an alkaline, lime-based absorber to scrub gases from air gas streams in flues. Dry FGD systems use lime injected directly into flue gases, while wet FGD systems use a lime-water slurry that is injected into flue gases.

FGD scrubbers use lime because it reacts well with SO2 and HCI. Often, FGD scrubbers are used as a polishing stage in larger industrial air filtration systems.

Sizing and specifying the right air filtration systems

When designing industrial air filtration systems, our primary aim is to ensure that the design can achieve a specified level of particulate cleanliness.

Depending on the nature of your activities, your air filtration system might be as simple as extraction > filter > vent, where we take exhaust gases, filter particulates with a carbon filter, and release treated air into the atmosphere.

Or your activities might demand multi-stage treatment, where two or more air filtering stages are used to achieve a specified air quality. For example, odour fumes can be removed with a biofilter and chemical fumes with a dry scrubber.

At PDFL, we offer a full turn-key solution for industrial air filtration, offering full design, installation and maintenance. Our systems are designed on a project by project basis and built to BS4994, with WIMES 8.05 compliance.

Call us on +44 (0)1922 418005 today to find out more.