Industrial Odour Control

Odours originate from chemical compounds that can be detected by the sense of smell. These are often organic compounds, such as hydrocarbons like alkanes or alcohols, but inorganic compounds, like carbonates and sulfates, which do not contain carbon, can also produce strong odours. Typically, it is a type of odour cocktail made up of dozens or even hundreds of different compounds.

Whether we perceive an odour as positive or negative depends on many factors: the chemical composition of the odourants, the intensity of the smell, and personal characteristics, such as individual experiences with a particular odour. Since odours can arise from countless substances and combinations of these, clear classification based on odour characteristics and properties is challenging. Therefore, selecting and designing suitable technologies for odour control also requires significant expertise.

Odours are often the result of chemical, biochemical, and technical processes, which are present on a small scale in households but are especially common in industry. Examples include the production of pet food and animal feed, the waste and recycling industries, and rubber processing industries. The decomposition of substances, such as through fermentation, decay, or heating, leads to the release of intense odours during the production process. If process air is released into the environment without filtration and effective odour reduction, it is quickly perceived as a nuisance due to the relatively high concentration.

Whereas substance concentrations can be measured quantitatively, odour intensity measurements rely on the human nose. Independent odour laboratories conduct olfactometric measurements according to DIN EN 13725 in conjunction with VDI Guidelines 3882 Part 1 and Part 2. In these measurements, selected test subjects are presented with odour samples in a controlled sequence. Starting with highly diluted samples and increasing the odour concentration with each sample, the perception threshold of the odour for each tester is identified. Using the identified perception threshold and the corresponding dilution factor, the odour concentration of the undiluted sample is determined. The odour concentration is expressed in odour units per cubic meter (OU/m³). Independent odour laboratories are also typically employed to assess the effective odour reduction performance during the acceptance of industrial odour reduction systems.

Volatile organic compounds are generally referred to as VOCs (Volatile Organic Compounds). They are gaseous and vaporous substances that are released into the ambient air. In production processes, VOCs can be generated, for example, through the drying of materials or the evaporation of solvents.

Olfactometry refers to the controlled measurement of odour sensations experienced by test subjects. The devices used for this purpose are called olfactometers.