The fixed bed is installed in the compartment for the biological purification and consists of plastic tubes in a lattice structure that has been optmised through many years of practical experience. This way a microbacterial biotope is created that is perfect in every way (the so called biofilm).

Below the fixed bed that is completely surrounded by water, there are special aerators, that provide the microorganisms living in the fixed bed as the biofilm always with exactly the right amount of oxygen.

For the biofilm that means perfect working conditions caused by nutrients from the waste water in combination with the controlled aeration of the fixed bed.

The first chamber of the small sewage treatment system separates larger particles from the effluent (mechanical pretreatment). From there the effluent goes to the second chamber for the biological treatment. On the bottom of the second chamber an aeration system is installed, which provides a pre defined amount of air regularly into this chamber.

Excess or dead microorganisms will be carried away via this air stream and will be transporter along with the treated waste water into the third chamber for post treatment.  Here those microorganisms will settle on the floor and will be pumped back into the first chamber. The treated water will leave  finally the third chamber.