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Treatment of gaseous emissions through a wet scrubber – MESAR Environair inc.

Description of the technology

Wet scrubbing absorption technology allows treatment of pollutants in gaseous emissions. It is particularly applicable to acid emissions, combustion emissions, volatile organic compounds and odours. Pulp and paper, metallurgical and chemical plants are principal sources of these pollutants, as well as industrial waste incinerators.

Treatment of gaseous emissions with wet scrubber absorption involves the neutralization of the pollutants by means of a purifying liquid. This liquid, whose nature varies according to the pollutants being treated, is put in contact with the gaseous emissions. The pollutants are captured by the liquid and removed from the gaseous effluent. At the system’s outflow, process water can be discharged into municipal sewers or, if required, piped into a treatment system.

Nature of the contaminants being treated by the process
Acid emissions

  • Hydrogen chloride, HCl
  • Fluorhydric acid , HF
  • Sulfuric acid, H2SO4
  • Nitric acid, HNO3
  • Phosphoric acid, H3PO4
  • Chlorine, Cl2

VOCs (volatile organic compounds) (Recovery of alcohols)

  • Alcohol
  • BTEX *
  • Phenol
  • Nitrous compounds
  • Sulfurous compouns

* benzene, toluene, ethylbenzene and xylene

Combustion emissions

  • Sulfur dioxide, SO2
  • Nitrogen oxydes, NOx


  • Hydrogen sulfide, H2S
  • Ammonia, NH3


The gaseous effluent treatment system perfected by MESAR/ENVIRONAIR eliminates most of the pollutants contained in the gaseous emissions. It self-adjusts to variations in the concentration of pollutants in gaseous emissions undergoing treatment and the response time is less than 2.5 seconds.

A removal efficiency of 99% of the purification droplets (<5 microns) is achieved, thus minimizing the quantity of liquid which could require further treatment in certain cases, or which might escape into the atmosphere. In addition, 98% of the chemical reagents (purification liquid) used are recovered.


Acceptable flow rates for the system vary from 1700 to 85,000 m /hour.

Installation and operation

MESAR/ENVIRONAIR’s technology requires the installation of two main components, the Absorption Tower purification system and the Reagent-Effluent Control System unit. The purification system is a treatment column which includes:

  • gas diffuser ;
  • packing or absorption zone;
  • purification liquid diffuser;
  • mist eliminator;
  • purification liquid sump

Gaseous emissions are first introduced at the base of the treatment column, where a gas diffuser ensures that they are evenly distributed through the system. They are then put in contact with the purification liquid in the packing or absorption zone. A second diffuser ensures that the purification liquid is evenly spread. Gaseous emissions then pass through the mist eliminator situated at the top of the treatment column. Droplets of liquid carried by the purified gases are intercepted and returned to the absorption zone. The purification liquid is collect in a sump tank.

The unit maintains a constant control over the quantity of purification liquid being injected into the treatment tower, as a function of pollutant concentration in the gaseous emissions.

Dimensions of MESAR/ENVIRONAIR’s treatment system vary according to the air flow being treated. Each system is tailored to the client’s specific needs. Components are then manufactured in the plant, assembled and installed on-site. MESAR/ENVIRONAIR takes responsibility for personnel training and system start-up.


The cost of treating gaseous emissions using the absorption technology varies as a function of the quantity and type of pollutants being treated. Overall cost (design, fabrication and installation) of a system ranges from $100,000 to $1,000,000 for flows of 1700 to 85,000 m 3/hr. For example, cost of a complex system to treat 42,500 m 3/hr of gaseous emissions from a munitions incinerator in Lübben, Germany, was $1,500,000.

Additional information

Presently, several MESAR/ENVIRONAIR gas and odour treatment systems are operating world-wide. Three of these are in Quebec: at INA waste water treatment plant (gaseous effluent containing ammonia and H2S); in a metallurgy plant in Valleyfield (chlorine gas); and at W.R. Grace’s plant in Valleyfield (process gases containing ammonia and hydrochloric acid). The other systems are in Ontario, the U.S., Germany, Latin America and South America (Argentina and Uruguay). MESAR/ENVIRONAIR has been developing this technology over the last five (10) years.

Monsieur Yvan Massé, ing., Président

3825 Jean-Marchand
Québec, Québec, G2C 2J2

Phone :    (418) 688-7475
Fax :    (418) 843-9269
Email :    quebec@environair.com
Web site :    www.environair.com