Patent ID: 7544287

Claim:
A biological reactor vessel comprising: 1) a tank having an inlet and an outlet and a treatment volume for receiving and delivering a liquid to be treated; 2) an assembly of media substrate having a biofilm support surface, said media substrate being positioned within the treatment volume within the tank to serve as a biological support to carry a biofilm to be contacted by the liquid to be treated; 3) a drive system for agitating the biological support while said assembly of media substrate is located at least partially inside the treatment volume; wherein the drive system causes the assembly of media substrate to oscillate with a reciprocating motion having a predominant component that is in the horizontal direction while at least a portion of the media substrate remains continuously immersed within the treatment volume so as to expose the immersed biofilm to a reciprocating shearing force directed alternately in opposite horizontal directions along the biofilm support surface, such shearing force arising from the differential motion of the media substrate with respect to the liquid to be treated.