Destruction Technology During VOCs Treatment-2

Destruction technology

Biodegradation

The principle of the biodegradation method is to use microorganisms to decompose the organic matter contained in the exhaust gas into CO2 and water, that is, the organic matter in the exhaust gas provides energy and nutrients for the microorganisms. Biological treatment of volatile organic compounds generally includes the following steps:

1) Volatile organic compounds diffuse from the gas phase body to the gas-liquid phase interface and dissolve in the liquid phase;

2) Diffusion of volatile organic compounds from the liquid film into the biofilm driven by the concentration difference;

3) In the biofilm, the volatile organic compounds are captured by microorganisms and degraded and absorbed;

4) Volatile organic compounds are decomposed as energy and nutrients in the metabolic activities of microbial life;

5) The metabolites partially diffuse into the liquid phase, where the gaseous substances diffuse into the gas phase. The process is shown in Figure 3.

Gas mass transfer process

There are three main types of biological treatment technologies commonly used in the industrial field: biological trickling filter towers, biological filters and biological scrubbers.

Schematic diagram of biological trickling filter tower

The biological trickling filter tower is simple to operate, and it is easy to investigate the effect of nutrients on performance; however, there are problems such as the easy loss of microorganisms with the liquid phase, and the clogging of the reaction bed caused by excessive addition of nutrients.

Schematic diagram of biological filter device

The biological filter requires less external nutrients and is easy to degrade VOCs that are insoluble in water; the disadvantage is that the filler is easy to age, and the humidity and pH of the filler are difficult to control.

Schematic diagram of biological scrubber

The biological scrubber has mild reaction conditions and stable operation; however, the operating cost is high, and the VOCs treated need to be easily soluble in water. The main unit of biodegradation treatment of waste gas is microorganisms. It is one of the future development trends of this technology to cultivate microorganisms that can adapt to different environmental conditions, have a short culture period and maintain high activity for a long time.