Biofilters are effective in odor reduction. Purenviro designs and delivers biofilters in all sizes and to a number of different applications. The technique is proven and well documented. Biological odor cleansing has many advantages. When conditions are exactly right, there are only a few other techniques which can compete with biofilter.

How a biofilter works

A biofilter cleans the air by biological activity. The air is passes through a filtermaterial which is biologically active. The air and pollution are absorbed in the filtermass, and bacterias and microorganisms break down the substances and make sure that the filter can absorb odor and pollution continuously. The filtermass is kept moist, and the pH value is regulated to make sure there are enough nutrients.

When to choose a biofilter

Biofilters are suitable when there are low concentrations and the airflow is small or medium. It is specified as BAT (best available technique) in most sectors that has odor issues. Since the filters are biologically active, the process should be run continuously. The conditions should be warm and moist however the temperature must not exceed 40 degrees Celsius.

  • High removal rate, 95% - 99%
  • Low energy consumption
  • Easy maintenance
  • Simple design
  • Demands little or no chemicals
  • Low operational costs

Biofilters are used in a number of different industries. The construction is simple, and in most cases adapted to each process. Here are some of the most ordinary applications.

Odour reduction from feed industry

Biofilters are very suitable in odor reduction when producing feed. A very high efficiency is achieved. The air is often warm, and with the right pre-conditioning, optimal conditions can be achieved in the filter. A removal rate of up to 95-98% with minimum amount of energy consumption is guaranteed.

Wastewater treatment

Odor from wastewater treatment and pumping stations consists of substances, which are effectively cleansed in a biofilter. Temperatures are not often so high, but there are continuous operation and stable conditions throughout the year. These conditions are very suitable for biofilter.


Biofilters are very common in cleaning odor from composting plants. By composting waste from food, a number of smells with low odor threshold are formed. The biofilter proves high efficiency and has many applications at composting plants.

Food industry

Exhaust from food production is often warm and moist and therefore very suitable for biological odor cleansing. Biofilter is specified as BAT in this sector.


Exhaust from biogas contains H2S which a biofilter can clean this effectively. The filter can be designed for applications in atex/ex zones.

Waste facilities

Waste facilities often gives their neighbours problems with odor. A biofilter is well suited for removing odor from waste, sorting, reception, storage and composting. In most waste facilities there are enough space to install a filter, and the airflow often has the right quantity.

The choice of construction depends on the size of the filter. Small filters can be delivered as containers in PP for excavation, or in combination of PP/Steel to place over ground. Large filters have to be built on-site, normally in concrete.

Små filtre i PP

Små filtre i PP plast kan leveres klare til nedgraving. Det gir rask installasjon og et pent resultat.

Biofilter in container

Larger filters are normally produced in combination of PP/Steel with insulation. These filters are traditionally placed over ground. The filters can be shaped in modules for easy transportation.

Biofilter in concrete

Larger filters are built on-site. The construction is in concrete.

A well-functioning biofilter demands management, control, good air-distribution and the right filtermass. We deliver all you need for a good filter with a high efficiency.

Bark and chips for filtermass

Bark and chips are amongst the most used materials in the organic biofiltermass. We mix together durable masses with the right composition and low pressure drop.

Extruded clay for filtermass

Inorganic filtermass has a long durability, and the pressure drop does not change during the lifespan of the filtermass. We deliver masses based on lightweight extruded clay particles (LECA).

Grating covers in PP/composite

To achieve a high efficiency, you have to have an effective air distribution. We deliver self-supporting grating covers for good air distribution. These can be designed for heavy loads, to handle smaller automobile machines.