Chemical gas scrubbers for industrial emission treatment (air pollution control and odor control)

Gas scrubber/Air scrubber for VOC abatement: crossflow scrubbers and counterflow scrubbers

for the separation of following components out of industrial and agro-industrial emissions :

  • H2S (hydrogen sulfide)
  • NH3 (ammonia)
  • HCl (hydrochloric acid)
  • SO2 (sulfur dioxide)
  • RHS (mercaptans or thiols)
  • CH2O (formaldehyde, formaline)
  • amines
  • phenol
  • HNO3 (nitric acid)
  • NOx (nitrogen oxide)
  • EO (ethylene oxide), …

What’s a gas scrubber?

A gas scrubber installation is one of the most used technologies for air pollution control (separation of hazardous or toxic components) and odor control (separation of odor components in case of odor nuisance) out of industrial emissions. A gas scrubber is used to bring the gas emissions or off-gases to be treated, in contact with a washing liquid (water with most of the time chemical additives), to separate components from the gas and absorb them into the liquid. In order to maximize the contact surface, tower packing is used to increase the performance of the scrubber. Synonyms for gas scrubbers are absorbers, wet scrubbers and industrial air scrubbers. Gas scrubbing is one of the most used technologies in the field of emission treatment and air pollution, as the gas scrubbing technology can be applied for the largest range of gas emissions (from all kinds of industries) to treat. Gas scrubbers can be used for separation of hazardous or toxic industrial emission components (air pollution control, volatile organic compound or VOC abatement in industrial emission treatment) as well as for separation of odour components (odour control/odour abatement).

Gas scrubber : how does it work

Gazeous components out of industrial emissions will be absorbed in the liquid present in the gas scrubber. In what extend the absorption will be possible, will entirely depend on the solubility of these various gazeous components. It goes without saying that also the initial temperature of the off-gases will have a certain influence. The washing liquid consists of water (wet scrubbers), with added chemicals. The composition of the washing liquid entirely depends on the nature, initial concentration and composition of the components to remove, as well as on the efficiency premises of the gas scrubber.

According to the flow direction of the off-gases with versus the washing liquid, we distinguish counterflow scrubbers (liquid and gas are moving in opposite directions) and crossflow scrubbers (liquid and gas in crossed directions). For certain applications, a combination of both types will be the best solution.

A gas scrubber or air scrubber mainly consists of following components : scrubbing vessel or tower (packed column), tower packing (structured or random, Pall rings, Raschig rings), droplet separator, spray nozzle(s) or liquid distributor, pump, chemical dosing systems, measure and control instruments (pH, redox), water supply system.

Gas scrubbers custom made – integrated solutions

Our gas scrubbers are always custom made, especially designed for the gas emissions offered and adaptable to the customer’s demands. For each application, the concept has been well considered, to allow for adaptation according to production changes (different composition of the off-gases, flow increases); all this within certain limits. This way, the gas scrubber can be adjusted in an economic way, whenever necessary. All gas scrubbers are designed to integrate seamlessly in the existing production environment.

Gas scrubbers can be conceived for smaller off-gas flows (compact models for storage tanks and laboratories), as well as for larger gazeous emission volumes. The key to success for a functional, easy maintenance scrubber installation? A good and well-thought-out design right from the start. Contact us for more information.

Gas scrubbers : the advantages

  • relatively simple concept and well controllable, also for larger gazeous emission volumes
  • low energy consumption
  • compact and space saving
  • predictable and guaranteed performance
  • high efficiency
  • maintenance-friendly
  • wide deployability, in various industrial sectors, for a wide range of applications

Gas scrubbers : the disadvantages

  • waste water needs further treatment
  • water- and chemical consumption
  • freezing sensitiveness
  • too much dust and/or grease in the gas emissions can cause fouling of the tower packing
  • for some odour control applications, preliminary pilot tests are highly recommended, to assess the feasability(more info on the  pilot gas scrubber page)

Most important industries for VOC gas scrubbers and odor control scrubbers

  • waste collection and waste treatment industry
  • chemical and pharmaceutical industry
  • petrochemical industry
  • food industry
  • fertilizer manufacturers, manure processing
  • animal feed industrie, petfood manufacturers
  • oil processing industry
  • electronics
  • metal and surface treatment

Heat recovery system in combination with air scrubber installations – green energy out of gas emissions for energy cost reduction

Most types of air scrubbers can be optionally provided with a heat recovery system. The heat recovered can be used to increase for instance the temperature of all kinds of process water (see also our process water – membrane filtration section). This kind of heat recovery system allows to considerably cut energy costs. It would be highly regrettable to waste the heat out of your production process, considering the actual energy cost. It goes without saying that the integration of heat recovery systems can also be realized as part of a gas scrubbing optimization project (optimization of existing gas scrubbers).


In short, the key to success for a functional, troublefree and low maintenance emission treatment installation? A well dimensioned and well considered scrubber design, right from the start?. Do not hesitate to contact us with all your questions. The case studies below are a short overview of our gas scrubbing installations. Below case studies are systematically completed with text and pictures. Click the pictures to get access to the full project description.