Odour control case study: replacing a biofilter with an AIRCONNECT® - AIRCON® V-XL activated carbon system

Biofilters as odour control systems: flavour production

Flavouring substances are widely used in the food industry and are chemically defined substances with flavouring properties. Depending on the production process, flavourings can be divided into two major groups:

  • Natural flavours
  • Synthetic flavours

Onion odour removal

Onion odour removal Natural flavours are products that are naturally present in plant and animal source materials. They are isolated by, for example, solvent extraction with alcohol or supercritical carbon dioxide (CO2) or distillation processes, where target compounds are separated from a natural mixture. Synthetic flavours are produced by chemical methods and then isolated. During the production of these flavours, odorous compounds can escape into the air of the production hall. These production halls are ventilated and odour control systems such as biofilters or scrubbers are used to remove the odour from the air. As these systems are often not 100% efficient, complaints can rise; especially when the production facility is in the close vicinity of urban areas.

Case study: replacing a biofilter with an activated carbon filter

Garlic smell removal

Garlic smell removal At a natural flavour producer, the air from three production halls was treated with a large biofilter (compost filter): L x B x H = 48m x 25m x 6m resulting in following operating conditions:

  • Total flow rate: ca. 45,000 m³/h
  • Superficial contact time (SCT) or empty bed contact time (EBCT): 576s
  • Linear velocity: 0.01m/s
  • Wet scrubber to humidify the air
  • Odour inlet concentration of ca. 43,600 OUE/m³ (OUE = European odour units).
    • The odour originates from organic sulphur compounds: mainly thioallyl compounds and sulfoxides
Definition European odour unit (OUE)
OUE (European odour unit) – A value in OUE is a mass measurement. One OUE is the mass of pollutant that, when evaporated into 1m3 of odourless gas (at standard conditions), results in a mixture with a concentration equal to the detection threshold for that pollutant.How “strong” is an odour unit?According to generalised assumptions based upon laboratory - based experiments on perceived intensity:
  • 1 OUE m-3 is the point of detection
  • 5 OUE m-3 is a faint odour
  • 10 OUE m-3 is a distinct odour

The first years after start up, the biofilter worked quite well. But in the past few years the natural flavour producer had many operational problems (and costs) and the biofilter’s efficiency was very unstable, ranging from bad to virtually zero…

Activated carbon filters: an efficient odour control system!

After some odour nuisance complaints from the neighbourhood, the natural flavour producer started a search for a solution and contacted DESOTEC Activated Carbon.  Our technical engineers evaluated the situation with the customer and it was decided to install an AIRCON® V activated carbon filter filled with ORGANOSORB® 10-CO as a full scale pilot to treat ca. 25.000 m³/h. Only a few days after the first contact DESOTEC delivered the AIRCON® V filled with ORGANOSORB® 10-CO. During the test period, the biofilter was not functioning at all and the AIRCON® V was giving an overall odour removal efficiency of 99.8% which is well above the 90% required by the operating permit. Based on the results, the final long-term and energy saving solution was to bypass the biofilter and install an AIRCONNECT® - AIRCON® V-XL system filled with ORGANOSORB® 10-CO. The AIRCONNECT® - AIRCON® V-XL is now operating successfully for more than one year and since then there have been no more complaints from the neighbours. Interested in tailor-made odour control solutions? Don’t hesitate to contact us. We’re at your service!