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Reference project

100% odor removal at sewage treatment plant

Air treatment .
H2S odor removal
Odor control
Wastewater treatment plant
Air flow
22,000 m3/h
100 % H2S removal


The synergy between catalysis and ozonation ensures H2S and odor-free emissions

Our client in this case is the wastewater treatment plant in one of the bigger cities in Sweden.

It was built in the 1960s and has since been renewed and rebuilt many times. A major rebuilding took place during 1979-80, including the incorporation of a biological step. Recently, another upgrade was necessary due to a higher capacity demand partly caused by the added treatment of the wastewater from a nearby city. The planning for this began in 2015—the first steps included identifying the location as well as designing new pools and biological steps. The project continued until early 2019 when the new facilities started their operations.

The problem.

Hydrogen sulfide or H2S is an air pollutant well-known in the sewage treatment industry.

It is emitted from the wastewater and diffuses in the surrounding air. Disturbing odor problems are often related to H2S emissions, due to the high sensitivity of the human nose for this compound. Since new facilities were going to be built, increasing the wastewater load, a system for treating H2S was mandatory. This case was particularly complex because various streams needed to be treated, with a diffused H2S emission.

The solution.

Complex problems often require complex solutions. In this case, the proposed solution was to treat all streams with a combination of catalysis and ozonation.

Most of the H2S was removed using two units of the Nodora Cat, the catalytic version of our widely used Nodora air treatment system. The main difference between the two versions is the material composing the filter. Our Rubicat™ catalyst was used in this version of the Nodora Cat. It is designed to selectively remove H2S from polluted air streams, even at high concentrations.

Ozone was used as a final polishing step, ensuring zero odor emissions. The ozonation step included three Ozonetech RENA Pro ozone systems. These units are the most powerful ozone systems in our portfolio, producing highly concentrated ozone. The oxidant is injected into the ventilation ducts just after the catalytic stage, using the ventilation system as reaction chamber.

An optimal configuration was obtained by splitting the ozone flow and injecting it into different process streams, according to the various requirements. This configuration resulted in a very accurate use of the produced ozone, optimizing energy consumption and operational costs.


Our combined Nodora Cat and Ozonetech RENA Pro system proved to be very effective at removing H2S and all related issues. No H2S was detected after the Nodora Cat stage with the ozonation stage abating the remaining odorants and ensuring no H2S or odor emissions, even in the case of high peaks.

Measuring the pollutant concentration at the outlet of the system, the H2S removal was 100%, confirming the effectiveness of the tailored solution.