Technical analysis of the criteria used in the design of systems for the treatment of fumes, particulate matter and odorous compounds. Industrial Emissions Directive (IED), BAT, EN 16282, EN 16798-3 and the operating principles of electrostatic precipitation, adsorption, oxidation and wet scrubbing.

Fume Treatment as a Process

A fume treatment system must be designed according to the characteristics of the emission source.

Airflow rate, temperature, particulate concentration and particle size distribution, together with the presence of grease aerosols, volatile organic compounds and odorous substances, directly affect the behaviour of the treatment system.

Different technologies can therefore be used individually or combined in several stages. Overall performance depends on the correct sequence of treatments, fluid dynamic conditions and maintenance.

Regulatory and Technical Framework

The Industrial Emissions Directive 2010/75/EU, amended by Directive (EU) 2024/1785, regulates installations falling within its scope and uses BAT, Best Available Techniques, as a technical reference for defining environmental permit conditions.

For the food industry, BAT conclusions are contained in Commission Implementing Decision (EU) 2019/2031 for the food, drink and milk industries. The document applies to the activities and production capacities specified by the Industrial Emissions Directive and should not be interpreted as a general requirement for all commercial kitchens.

For commercial kitchens, EN 16282-1:2018 defines general requirements for ventilation systems and includes a method for calculating airflow rates. EN 16282-7:2026 covers fixed fire-extinguishing systems designed to protect commercial kitchen equipment and areas exposed to grease fires.

EN 16798-3:2025 applies to ventilation, air conditioning and cooling systems in non-residential buildings intended for human occupancy. Industrial process ventilation is outside its specific scope.

In Italy, odour emissions are regulated under Article 272-bis of Legislative Decree 152/2006. In 2023, the Italian Ministry of Environment and Energy Security issued national guidelines for the application of Article 272-bis to plants and activities producing odorous emissions.

Treatment Technologies and Separation Mechanisms

Technology	Principle	Main Parameters Affecting Performance
Mechanical filtration	Physical separation of particles	particle size, velocity, filter area, pressure drop
Electrostatic precipitation ESP	Electrical charging and collection of particles	velocity, cell geometry, electric field, concentration, cleaning condition
Activated carbon	Adsorption on a porous surface	carbon mass, contact time, temperature, humidity, contaminant type, saturation
Ozone	Chemical oxidation	concentration, contact time, temperature, humidity, mixing
Wet scrubbing	Gas-liquid contact and mass transfer	geometry, water-to-air ratio, liquid distribution, velocity, contact time
RTO / thermal oxidation	High-temperature oxidation	VOC concentration, temperature, residence time, heat recovery

Electrostatic Precipitation

In an electrostatic precipitator, particles are electrically charged and subsequently collected on collecting surfaces.

The technology is suitable for treating fine particulate matter, aerosols, oil mist and visible smoke.

Performance does not depend solely on installed electrical power. Air velocity, flow distribution, particle size and the condition of the electrostatic cells directly affect the separation process.

Activated Carbon Adsorption

Activated carbon uses a porous structure with a large internal surface available for adsorption.

Contact time between the air and the adsorbent is an important design parameter, together with carbon mass, temperature, humidity, contaminant concentration and chemical characteristics.

Progressive saturation requires periodic replacement or regeneration of the adsorbent material.

Oxidation by Ozone

Ozone is a strong oxidising agent capable of reacting with different organic compounds.

In air treatment applications, the result depends on the relationship between the amount of ozone introduced and the contaminant load, the available reaction time and the physical conditions of the airflow.

System design must therefore consider the complete process rather than only the nominal ozone generator capacity expressed in grams per hour.

Wet Scrubbing

In wet scrubbers, treatment takes place through direct contact between the gas phase and the liquid phase.

Water consumption alone does not determine system performance. Machine geometry, droplet size, liquid distribution, turbulence, relative velocity and residence time affect mass transfer between the two phases.

Two systems operating with the same water flow rate can therefore produce different results.

Why Multiple Treatment Stages Are Used

An emission may contain particulate matter, aerosols and odorous compounds at the same time. A single treatment principle may not be suitable for all fractions.

A possible configuration is:

capture → particulate separation → electrostatic precipitation → odour treatment → ventilation → discharge

In other applications, the appropriate sequence may be:

capture → wet scrubbing → droplet separation → additional treatment → discharge

The sequence must be defined according to the emission source and the characteristics of the contaminants.

Fluid Dynamics and System Sizing

A treatment system must operate within its design conditions.

Airflow rate, duct velocity, pressure drop, temperature, cross-sectional areas, fan operating point and velocity through each treatment stage must therefore be verified.

Sizing based only on room volume does not correctly describe a source that generates fumes, vapours or particulate matter through a specific process.

Even correctly selected treatment technology may lose part of its effectiveness when airflow distribution is uneven or when operating velocity exceeds the intended design range.

Maintenance and Performance Stability

Operating conditions change during the service life of a treatment system.

Particulate deposits on electrostatic cells, saturated activated carbon, blocked nozzles, deposits inside ductwork or changes in airflow rate can modify the initial performance of the system.

Maintenance intervals must therefore be defined according to the process, operating hours and contaminant load.

Where required by legislation or environmental permits, emission measurements provide a method for checking system behaviour under actual operating conditions.

Designing the Treatment System from the Emission Source

The selection of a treatment system should begin with the characteristics of the emission source.

The technical process starts with emission characterisation, continues with the definition of airflow rate and contaminants to be treated, and then determines the technology or combination of technologies required.

The relationship between emission source, fluid dynamics, separation principle and operating conditions determines the actual behaviour of a fume treatment system.

Technical and Regulatory References

Directive 2010/75/EU on industrial emissions, as amended by Directive (EU) 2024/1785.

Commission Implementing Decision (EU) 2019/2031, establishing BAT conclusions for the food, drink and milk industries.

EN 16282-1:2018, Equipment for commercial kitchens – Components for ventilation in commercial kitchens – General requirements including calculation method.

EN 16282-7:2026, Equipment for commercial kitchens – Components for ventilation in commercial kitchens – Installation and use of fixed fire suppression systems.

EN 16798-3:2025, Energy performance of buildings – Ventilation for buildings – Performance requirements for ventilation and room-conditioning systems.

Italian Legislative Decree 152/2006, Article 272-bis, and national guidelines issued by the Italian Ministry of Environment and Energy Security on odour emissions.

Author: Artur Cokaj — Researcher and designer of air treatment technologies.

Author of the upcoming book "WATER SCRUBBER TECHNOLOGY

- Scientific, fluid dynamic, and engineering principles of fume treatment".

Inventor, holder of the industrial invention patent No. 102022000000572.

Technical Manager in charge (D.M. 37/2008 Letters A, C, D, E).

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