In addition to volatile organic compounds (VOC), inorganic substances are also common contaminants in gas flows. In many industrial sectors, production-related odours arise that are unpleasant and sometimes hazardous to health. All of these must be removed from the exhaust air using a suitable cleaning method before it can be released into the environment as clean air. There are various exhaust air and waste gas purification methods that remove odours absorbently or biologically. Legal thresholds in the TA Luft (Technical Instructions on Air Quality Control) and the Odour Immission Guideline (German: Geruchsimmissionsrichtlinie, GIRL for short) determine when exhaust air is considered ecologically and health-wise as safe clean air.
Odours are often mixtures of organic and inorganic compounds, as well as odorous individual substances. It is not uncommon for odours to be composed of several hundred components of varying concentrations and properties. Among others, there are aliphatic, aromatic or halogenated hydrocarbons as well as oxygen-, sulfur- and nitrogen-containing compounds, such as aldehydes, alcohols, esters or amines. Inorganic substances such as hydrogen sulfide and ammonia are also very odour-intensive.
Many odours are perceived as pleasant. However, this impression often changes with permanent exposure. There is also a whole range of unpleasant odours and those that are highly dangerous if inhaled due to the substances they contain. To prevent such variants from being released unpurified into the environment, exhaust air purification technologies such as odour filters are mandatory in many industrial and municipal sectors.
A wide variety of production processes often generate particularly high odour emissions. These include waste management, (petro)chemistry or food production. Odours also exceed the legal thresholds in textile production, plastics processing or paper mills and many other sectors. And everywhere, odour reduction measures must be installed so that in the end clean air is released into the environment.
In most countries of the world, there are legal regulations for odour reduction of industrial exhaust air. In Germany, the Federal Immission Control Act describes the limits that must be complied with. The Federal Odour Immission Guidelines (GIRL) define the exact requirements and the limits of acceptable odour immissions. The GIRL is anchored in the current TA Luft.
The technological options for odour reduction are as diverse as the individual odour substances. Frequently used methods for odour removal are bio scrubbers, biofilters, adsorbers or chemical scrubbers. Which exhaust air purification system is best suited for the process gases of the most diverse industries can also be determined in advance by tests for new applications.
With more than 250 supplied exhaust air purification systems for the separation of odorous substances alone, Wessel-Umwelttechnik is a competent and experienced partner for a wide range of industrial sectors.
Wessel-Umwelttechnik relies on two biological processes for the purification of exhaust air containing harmful substances and odours: BIOCAT bio scrubbers and BIOCAT biofilters. Of central importance for both biological exhaust air purification systems are microorganisms and biocatalysts that break down pollutants and odours into naturally formed products such as carbon dioxide and water. The prerequisite is that the exhaust air components are bioavailable and have a certain solubility in water.
In chemical-absorptive exhaust air purification, gas scrubbers are used, among other things. Wessel-Umwelttechnik focuses on the so-called DCS scrubbers (short for: Direct Chemical Sorption). DCS scrubber technology has efficiencies of more than 90 % for different odorous substances. These include: NH3, HCl, HF, CH2O, H2S, SO2, as well as mercaptans, amines, ketones, aldehydes, and alcohols. DCS scrubber technology is the process of choice for a wide range of applications.
Adsorptive exhaust air purification using activated carbon is also a proven technology for odour removal. This solution can also be used for multi-substance mixtures as well as for an economical solution for processes that are not operated continuously. Adsorptive exhaust air purification is also well suited for the treatment of exhaust air with critical exhaust air components.
Since the space conditions on site and the process gas compositions are different for every company, we offer modular exhaust air purification systems. Depending on the location, the odorous substances and the number and type of other pollutants in the exhaust air, different technologies and systems can be combined. Always perfectly matched to the respective needs.
