Microbial purification is a method of VOC decomposition developed in recent years. This technology has been widely used in Germany and the Netherlands, and the removal rate of organic matter is more than 90%. The essence of the process of VOC purification is the process of using VOC as carbon source and energy source to maintain the life activities of microorganisms attached in filter media under suitable environmental conditions, and transforming organic matter into simple inorganic matter (CO2, H2O) or cell components. The treatment of VOC by microbial purification generally involves three steps
(1) VOC contacts with water and dissolves in water;
(2) The VOC dissolved in the liquid membrane is further diffused to the biofilm under the promotion of concentration difference, and then captured and absorbed by the microorganisms in the biofilm;
(3) The VOC entering the microorganism is decomposed as energy and nutrients in its own metabolic process, and finally transformed into harmless compounds through biochemical reaction.
According to the existing forms of microorganisms in VOC treatment process, the treatment methods can be divided into biological washing method (suspended state) and biological filtration method (fixed state). Biological washing method means that microorganisms and their nutrient ingredients exist in the liquid phase, and the organic matter in the gas phase is transferred to the liquid phase after contacting with the suspension, which is degraded by microorganisms. Its typical forms include bubble tower, spray tower, perforated tower and other biological washing towers. Biofiltration is a process in which microorganisms attach to the surface of solid media (packing). VOC is absorbed and degraded by microorganisms when it passes through the fixed tower layer (packing layer) composed of solid media. The typical form of biofilter is composed of soil, compost, filler and other materials. The biotrickling filter has both suspended and fixed characteristics.
Microbial purification method is generally used to treat low concentration VOC. Its main advantages are simple process and equipment, no consumption of useful raw materials, low operation energy consumption and cost, safe and reliable, less secondary pollution. However, due to the low biochemical reaction rate, the volume of the equipment is large, and there is pressure loss, so it is sensitive to the changes of temperature and humidity.
With the rapid development of industry and the acceleration of urbanization, the public has higher and higher requirements for the quality of living environment and working environment. VOC has been paid more and more attention because of its high harmfulness. According to its physical and chemical properties, choosing different methods to deal with VOC can not only reduce environmental pollution, but also achieve certain economic benefits. Therefore, VOC recovery and treatment technology will become increasingly active, and the application prospect is very broad.