The adhesion ability of biofilms - the most important indicator for evaluating the quality of fillers - Biological adhesion=protected surface area (related to the design structure of fillers) × Bioadhesion per unit surface area (related to the performance of the filler)

 

2、 Filler performance

 

Filler performance - the most important indicator for evaluating the bioadhesion of fillers

 

（1） Surface performance of fillers

 

1. Surface structure: It is generally believed that the surface roughness is high and the film hanging speed is fast.

 

2. Surface potential: Generally, microorganisms carry a negative charge, while the surface of the filler is positively charged, which is suitable for microbial growth. 3. Hydrophilicity: Microorganisms are hydrophilic particles, and the filler has good hydrophilicity and is suitable for microbial growth.

 

（2） Hydraulic performance

 

1. Porosity: The volume occupied by the filler, with a high porosity.

 

2. Shape and size: affect the flow pattern of water and airflow.

 

（3） Fluidization performance: related to the density of the filler. The density of the filler should be 0.97-1.03, and fluidization can be achieved with smaller aeration or stirring.