EEvolved MBBR Biofilm Media

Proper buoyancy is important to ensure the media is evenly distributed throughout the tank. If the media is not evenly distributed, the water may short circuit around the media/biology resulting in insufficient treatment. 

A media's bouyoancy is a result of the density and specific gravity of the material. if the specific gravity is too low (below .94) the media will float, which means that it will take a significant increase in airflow (to decrease the water density) to make the media mix uniformly thorough out the tank. 

Our staff has seen systems with "light" media (about .92-.93 specific gravity) that requires 2-3x the airflow for mixing energy. This is a substantial operational cost. Buying media that uses the right material to have proper buoyancy may be a slightly higher capital cost, but it will be worth the investment as you will need smaller blowers (less capital cost) and less airflow (less operational cost).

The strength of the media is extremely important to ensure that the media will not break down over time. If the media breaks down, it may escape from the retention screens and reduce the protected area available for biological growth, which will result in declining treatment performance.  

Strength is a result of the wall thickness and the strength of the HDPE material. Different materials will have different strength, which can be measured in a lab. The wall thickness directly impacts the strength as well. If the walls are too thin, the media will likely breakdown overtime.  

Our staff has seen systems with thin walls in which most of the media was gone in less than 2 years. Thicker walls may mean slightly higher capital cost, but it will be worth the investment to have media that will last 15-20 years.   

This has been optimized to provide the right balance of protected area for biofilm growth and open area for water diffusion.