Biofilm is one of the latest series of challenges brought by scientific and technological progress to disinfection and sterilization industry. A compound of bacterial clumps and extracellular matrix, which adheres tightly to (the surface of reusable medical devices) and is difficult to remove.

Biofilm has the function of dividing and separating cells and organelles. Biofilm is a phospholipid bilayer embedded with protein and glycoprotein, which is an important part related to many energy conversion and intracellular communication. At the same time, there are a lot of enzyme binding sites on the biofilm. The main components of biofilm The main components of biofilm are lipids, protein and sugars, in addition to water, inorganic salts and a small amount of metal ions.

Influencing factors of biofilm formation

The formation of biofilm is related to the surface properties of carrier (hydrophilicity, surface charge, surface chemical composition and surface roughness), microbial properties (microbial species, culture conditions, activity and concentration) and environmental factors (PH value, ionic strength, hydraulic shear force, temperature, nutritional conditions and contact time between microorganisms and carrier).

Biofilm method

Biofilm method is an efficient wastewater treatment method, which has the characteristics of less sludge, no sludge expansion, strong adaptability to the change of wastewater quality and quantity, simple operation and management. Biofilm method is to attach microorganisms to the surface of carrier to form biofilm. When the sewage flows through the surface of the carrier, the organic matter and dissolved oxygen in the sewage diffuse into the biofilm. In the presence of oxygen, microorganisms in the membrane decompose and metabolize organic matter, and at the same time, the decomposed metabolites diffuse from the biofilm into the water phase and air, thus degrading the organic matter in wastewater.

The difference between activated sludge process and biofilm process lies not only in the suspension and adhesion of microorganisms, but more importantly, the diffusion process is a factor that must be considered in biofilm treatment system. In the biofilm reactor, organic pollutants, dissolved oxygen and various necessary nutrients first diffuse from the liquid phase to the surface of the biofilm and then enter the inside of the biofilm. Only the pollutants diffused on the surface or inside the biofilm can be decomposed and transformed by microorganisms in the biofilm, and finally various metabolites are formed. Therefore, biofilm is a stable and diverse microbial ecosystem.