US Patent 10392277 Backwash method for biological reactors

A media bed in a biological reactor is backwashed in a plurality of short pulses. An outlet of the reactor is preferably located above, but close to, the top of the bed. During a pulse, the outlet is closed and the bed may be fluidized or otherwise expanded to above the level of the outlet. Between pulses, the bed settles to below the level of the outlet.