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The grease and odor removal solution

Grease and Odor Treatment for Commercial Kitchens

Commercial cooking generates significant amounts of hot, greasy, and steamy air which is collected by hoods and extracted through ventilation ductwork. This way, a good working environment is maintained in the kitchen.

Purifying exhaust air with ozone is an efficient and dependable method in commercial kitchens and restaurants.

An ozone treatment reduces the grease deposits in the kitchen duct, providing numerous advantages. Fire safety will be improved, allowing the use of less expensive ducting materials compared to stainless steel and thereby reducing the capital investment. Additionally, treated exhaust air significantly reduces odors in the discharged air, enabling a more efficient energy recovery from the air.

Our solution

The RENA Kitchen Solutions is a high-performance ozone system specifically designed for commercial kitchens and restaurants equipped with one or multiple hoods. The system components are mounted on a stainless steel plate that can be positioned adjacent to or in another area beyond the kitchen.

RENA Kitchen Solutions has a remarkably low operating cost and requires minimal maintenance. This is primarily because the raw material, ambient air, is freely available and so, there is no need to purchase, transport, or manage any additional materials is not required.

Furthermore, using our RENA Kitchen Solutions system eliminates any need for moving parts, mechanical cleaning, fillings, and managing waste and residues. This simplifies operations and makes it possible for you to allocate less time and resources to daily maintenance tasks compared to what is otherwise needed.

Safety is paramount when it comes to the Kitchen Solutions system. The ozone production automatically shuts down in case anything unusual occurs. Additionally, the system is remotely monitored, and our Service Center is promptly notified whenever something happens. This allows for us to quickly resolve issues and ensure that the system can be restarted efficiently.

For further details on the RENA Kitchen Solutions, please refer to our brochure.

Showcasing RENA Kitchen Solution, complete set

Contact free air treatment

One of the main advantages of utilizing ozone gas for treating kitchen exhaust air is its contact-free nature that that makes maintenance requirements minimal. Because the system only features a passive nozzle inside the duct, it remains unaffected by the bombardment of grease droplets in this harsh environment.

Another benefit of using gas for treating air is its ability to reach every nook and cranny of the treatment area. There are no blind spots; all surfaces within the ductwork can be treated from a single injection point, with the dispersed ozone successfully reaching every grease molecule and particle. In contrast, a liquid cleaning agent, even when sprayed from multiple nozzles, may still leave some areas untouched.

For further insights into how grease is treated in commercial kitchen ventilation, please refer to our brochure.

Explaination of how ozone treatment eliminates grease in the kitchen ventilation
The right product in the right place

Multiple collaborative techniques

Efficient exhaust air treatment occurs in three main stages

Stage 1:

The primary defensive measure against grease and duct fires is to use hood-mounted mechanical filters. These filters are designed to (1) trap airborne grease droplets and (2) prevent flames from entering the ducting and igniting grease deposits adhered to the ducting.

Stage 2:

The secondary defensive measure against grease, duct fires, and odors involves incorporating an air treatment system, like the high-performance RENA Kitchen Solutions. This system then injects ozone into the air stream in order to neutralize the remaining grease and odor components.

As mentioned, the Ozonetech RENA Kitchen Solutions would serve as the second line of defense, treating grease aerosols with ozone before they can pose a threat to your business. By injecting pure ozone into the exhaust air stream, immerdiately after the mechanical filter, we achieve two key outcomes: (1) we significantly reduce grease build-up and (2)  we specifically target the odorous compounds.

Pure ozone can be viewed as a “pair of scissors” that cuts long, sticky, and complex grease molecules into smaller problematic components, all of which are both less smelly and less sticky. These more manageable substances are then carried away by the airflow.

Combine Rena Kitchen with Nodora Filter System

Stage 3 (Optional):

The third line of defence aims to eliminate odor:

When the final destination of the extract air is a sensitive area, such as a courtyard or an underground parking garage, a final and third polishing step is necessary in order to remove odors. In such cases, a combination of the RENA Kitchen Solutions system and the Nodora filter system is the ultimate solution.

The three treatment stages are illustrated below.

Explaining how Rena Kitchen and Nodora Filter system work together

How ozonation works

Ozone molecule

Ozone is generated on-site since it cannot be stored. All we need is oxygen and energy, and energy is obtained either from UV light or an electric field (ozone generator).

Allthough we commonly refer to ozone as a homogeneous gas, in reality, it is actually a mixture of oxygen, ozone, and oxygen radicals. It is ozone and oxygen radicals that react with the double and single bonds holding together fats (fatty acids) in long chains (molecules). Ozone and oxygen radicals act as oxidizing agents. Through reduction, fatty acids are oxidized.

Grease and cooking odors contain fatty acids in the form of aerosols or droplets. Oxidized fatty acids possess desirable properties. In ideal conditions, complete oxidation results in the production of only water and carbon dioxide. However, such ideal conditions do not typically exist in an exhaust duct.

In simple terms, our technology modifies the properties of grease and alters the composition of odors before the grease can cause any harm.

Reducing grease and odor with ozone

By utilizing ozone, airborne grease and odors undergo the following transformations:

  1. Grease and odor molecules are broken down, effectively reducing their presence in the air.
  2. The surface of grease particles is altered to make them “quick-dry,” preventing them from adhering to surfaces. This can be likened to removing one side of a Velcro strip, inhibiting their ability to stick.

Grease particles that do not adhere to the exhaust duct surfaces but instead follow the airflow significantly reduce the risk of duct fires. If the fire risk is reduced, it becomes permissible, according to Swedish regulations, to use cheaper duct materials. The need to clean the ducts also diminishes. Clean metal surfaces open up many possibilities for designing kitchen ventilation systems with heat exchangers.

Want to learn more about the challenges of exhaust air treatment?

Delve deeper into the challenges and benefits here!

Challenges in commercial kitchen exhaust

Keys to success over time

Having access to the necessary knowledge is a good start, whether it is your own knowledge or knowledge that we can provide for you.

A crucial aspect of effectively treating kitchen exhaust air is ensuring that the entire air treatment chain is tailored for the task.

With over 20 years of experience, we have been able to pinpoint the most common mistakes that people make when designing and installing ozone systems. For your benefit, we have compiled a list of several crucial points that we believe should be considered if you want to ensure that your ozone installation is successful.

Read about our 20 key factors for success in our Kitchen exhaust guide brochure.

Focus on safety

Chemicals are integral to our daily lives, being utilized in various capacities within our homes and communities. Chlorine and dishwasher detergent serve as examples of oxidizing agents that share chemical similarities with ozone.

  • Kitchens outfitted with ozone-based air purification systems, whether they utilize UV lamps or generators, should be equipped with an ozone sensor. It is imperative that you request this from your supplier. Typically, ozone should only be present in the exhaust duct and solely when the kitchen ventilation is operational. The role of the ozone sensor is to monitor the air quality within the kitchen and check the ozone levels specifically. In the unlikely event that ozone is detected within the kitchen, the ozone sensor ensures that the ozone system is promptly deactivated.
Ozone sensor

The requirements for ozone sensors are stringent. They must undergo traceable calibration and be delivered together with a NIST certificate. The Swedish Work Environment Authority has set a limit of 0.1 ppm ozone for an 8-hour workday.

  • The ozone/UV light system must be interlocked with the exhaust fan to ensure that they both operate simultaneously. Ozone generation should not occur when the ventilation system is turned off.
  • Kitchen hoods and clean-out doors must be equipped with signs saying “Warning – Ozone Treatment”.

Different Ozonation Techniques—A Comparison

Alternatives to ozone generators with HELS:

Other air treatment technologies, such as UV light, catalytic surfaces, or electrostatic precipitators (ESPs), must be installed inside the polluted airstream. However, these technologies are compromised by rapid grease buildup, which limits their effectiveness until they are cleaned.

The marketed use of catalytic surfaces (e.g., Ozone-Free UV) does not function well in dirty environments. No installations meet the requirements outlined in SS-EN 16282 Part 8 Annex E.

It’s also important to note that UV electronics are sensitive to high temperatures, which can occur above griddles and grills, making them a less than ideal solution.

For further information, please refer to our brochure on oxygen-fed or air-fed ozone systems.

Installed RENA Kitchen system

Ozone Treatment for Commercial Kitchen Ventilation & Restaurants

All you need to know about Air Purification and Heat Recovery in commercial kitchen ventilation and restaurants.

Want to learn more about standars and regulations?

Discover further information about industry standards and recommendations for commercial kitchens here!

Standards and regulations

Ozone vs Pure ozone.

When we refer to “pure ozone”, we are describing an ozone-oxygen mixture that:

  • Consistently contains 94% oxygen, with ozone comprising 10-14% of this mixture
  • Is free from nitric acid HNO₃
  • Contains minimal levels of nitrogen oxides (NOx)

The RENA Kitchen Solutions produces clean ozone.

In contrast, “ordinary ozone” generated by an air-fed ozone generator typically exhibits:

  • Ozone concentrations dependent on moisture, ranging from 0.1-0.5% (with 21% oxygen)
  • The presence of undesirable nitrogen oxides (due to the 78% nitrogen in the feed air)
  • Formations of nitric acid resulting from the reaction between nitrogen oxides and humidity
  • Creation of a salt from the acid, leading to electrode coating. This coating conducts electricity, short-circuiting the formation of the crucial corona (which emits a purple hue).

Even though using the surrounding air as the feed gas is a simple and cost-effective technical solution, as seen with air-fed ozone generators, it also comes with certain drawbacks:

  • Ozone production is significantly influenced by humidity levels. Higher humidity leads to lower ozone production. Just as moist air inhibits static electricity, moisture hampers ozone production. This is why dried oxygen with a dew point of minus 60°C is utilized for our RENA Kitchen Solutions system.
  • Air-fed ozone generators demand regular cleaning since the humid feed air leads to the formation of nitric acid in the generator; nitric acid, in turn, is highly corrosive. This issue is circumvented by using dried oxygen, as done in RENA Kitchen Solutions.

Read more about the differences between air-fed and oxygen-fed ozone generators here.


Pure ozone installation vs ordinary ozone installation
Exploring Best Practices: Case Studies in Effective Commercial Kitchen Ventilation

Here you can read a selection of our accomplished projects demonstrating the integration of sustainable and efficient solutions within the real estate industry.

Related reference project.

Central hamburger restaurant ensures effective and safe grease removal with ozone

Hamburger restaurant chose ozone to remove grease from kitchen exhaust air

Enabling the release of commercial kitchen exhaust into a garage

Historically significant building installs high performance solution for treating kitchen exhaust air