The principle of biological exhaust gas cleaning is based on microorganisms converting the contents of exhaust gas into harmless products. As the process always has to take place in a more aqueous phase than is available in the microorganisms' habitat, the microorganisms are either grown in a film of moisture on a substrate or suspended in an aqueous solution. The microorganisms are aerobic bacteria that oxidise the contents when oxygen is present.
The degradation performance of the micro-organisms is highly dependent on the environmental conditions: not only must enough oxygen and nutrients be available, but the temperature, pH and moisture levels also have a key role to play. Unlike a bio-filter, the advantage of a bio-scrubber is that it can control microbiological contamination on the exchange surface and keep this at a sufficiently low level.
SABA (Scheuch Anlage für Biologische Abluftreinigung, meaning Scheuch System for Biological Exhaust Air Cleaning) is the process of choice for separating organic contaminants – and particularly formaldehyde – from exhaust gases in the wood based panel industry; specifically, in MDF board production and press exhaust air cleaning. Compared with other processes, bio-scrubbers entail by far the lowest operating costs and are therefore the system of choice when it comes to separating formaldehyde.