Odor reduction at sewage treatment plants

Only a high-performance ozone treatment solution can get the job done

The water supply and sewage treatment in the municipality of Tierp, are handled by Tierps Energi & Miljö AB (TEMAB). The drinking water is made from groundwater, which is filtered and regularly inspected by Livsmedelsverket (The Swedish National Food Administration), to ensure the highest water quality before consumption. Water from showers, dishwashers and cleaning or any source of water that is led to the sewage, must be treated before reunited with nature. This is done to prevent the over-fertilization and pollution of our waters. In the cleaning process, the water is cleaned from physical objects, organic material and nutrients. The cleaned water is recycled to water in the vicinity, while the rest becomes a mixture called sludge. The sludge is then led to a treatment process in which it is made ready for disposal in landfills.


  • Name:

    Tierps Energi & Miljö AB, TEMAB

  • Location:

    Tierp, Sweden

  • Purpose:

    H2S & odor reduction

  • Performance:

    Average 87% H2S reduction in 5 m3/s airflow


  • Ozonetech RENA Pro series

  • Dimensions (HxWxD):

    1,800 x 800 x 600 mm

  • Input power:

    2.0 kW

Sewage treatment plant

The sewage treatment plant in Tierp, Sweden.

The problem

In the sludge treatment process, various odorous compounds can be formed due to microbial decomposition of organic matter, highly dependent on the type of wastewater handled (industrial or commercial). Amongst these compounds, the compound that is considered one of the worst malodors is the reduced sulfur compound, hydrogen sulfide (H2S). H2S is a very common odorant in sludge treatment processes that can be a large hindrance for the staff at the plant. H2S has a very distinct odor of rotten egg with an odor threshold in the size range of a couple parts-per-billion (ppb), meaning that any volatilization or leakage in the process may lead to highly unpleasant conditions, even to the extent that neighboring areas around the plant might file odor complaints.

The solution

The facility had already an old ozone system in place, but it generated little or no results. However, we were up to the task and installed an Ozonetech high-performance ozone system reducing H2S and odor from the wastewater treatment facility to a minimum, an investment resulting in a more pleasant working environment and a huge relief for the neighborhood. A high capacity Ozonetech RENA Pro system was offered, including sensor and full monitoring. The injection point in the ventilation was carefully chosen by working together with TEMAB in order to ensure maximum efficiency.


The Ozonetech RENA Pro reduced the H2S levels in the process ventilation from the sludge treatment basins significantly, reducing the odor levels at the facility as a whole by 87% compared to the former supplier’s ozone system. The careful design and optimization of the RENA and the ventilation system minimized risks for odor leakages and the risk of bacterial growth in the ducts.

Graph of before and after ozone treatment

The graph shows the daily average H2S concentration before we were called in. To the left is the daily average concentration for six days with no ozone treatment. To the right is the daily average concentration for six days of treatment using the former supplier’s ozone system.


Graph showing after Rena pro solution treatment

The graph shows a comparison of the daily average H2S concentration of the competitor’s solution and our Ozonetech RENA Pro solution. Over a 6-day period, the Ozonetech solution on average reduced the H2S concentration 87% compared to the competitor’s previous ozone treatment.