A fluidized bed reactor ( FBR ) is a type of reactor device that can be used to carry out a variety of multiphase chemical reactions. FBBR combines the best features of activated sludge and trickling filtratin into one process. The efficiency of FBBR is 10 times that of the activated sludge system and it typically occupies about 10% of the space required by stirred tank reactors of similar capacity. In this system there is uniform particle mixing due to the intrinsic fluid - like behavoiur of the solid material. For details consult https://en.wikipedia.org