Biological aerated filter is an advanced sewage biological treatment process, which combines the advantages of activated sludge and biological membrane method, and has two functions of biochemical reaction and physical filtration.

The modified ceramsite filter material is filled in the biological aerated filter, and a large number of bacteria grow on the surface of the filter material, and a certain biofilm is formed after a period of operation. In the process of degrading organic pollutants, the biological aerated filter grows a large number of new bacteria on the surface of the filter material due to assimilation, which thickens the biofilm. At the same time, due to the interception of some suspended matter, the head loss of the filter increases. When the head loss reaches a certain range, it should be backwashed to backwash the aging biofilm, and the backwashed water will flow into the regulating tank for reprocessing.

In the application of buried reclaimed water treatment engineering, due to the large lifting height of the biological aerated filter, the elevation layout is difficult to coordinate. It is generally used as a post-treatment process, but its elevation layout is still a thorny issue.