Another cost-effective and environmentally friendly alternative of waste air scrubbing is the replacement of a chemical washing stage by a biological one. As known from sewage treatment operations, microorganisms are therefore suspended in the washing solution.

If the environmental conditions of the microorganisms are optimally adjusted by pH control and addition of mineral nutriments, the microorganisms will grow and subsist on the waste air contaminants which are dissolved in the waste water. The microorganisms gradually settle on the packing material leading to an enlarged reaction area. After their full stabilization on the packing material, the uncontrolled elimination of these micro-organisms in the washing water is finally avoided. The washing liquid is continuously regenerated by the microorganisms which will in turn improve the transmission capacity from the gas into the liquid phase, thus the plant’s removal efficiency. Since the separated compounds are biologically oxidised, the use of oxidants is not required.

Being equipped as bio scrubber, this plant follows the function principle of biological air treatment:

• pH-neutral
• low energy consumption
• carbon-neutral regarding the decompositon of pollutants
• no use of chemical oxidants required

Coprresponding VDI guideline: VDI 3478, 1