The floating decanter utilizes a circular weir for decanting supernatant liquid and a flotation device for buoyantly supporting the weir within the basin. The floatation device also acts as a baffle to prevent scum from being withdrawn during the decant step.  For the successful operation of an SBR, the decanter must be designed to prohibit Mixed Liquor Suspended Solids (MLSS) from entering the decanter during non-decant sequences as well.  The Ashbrook weir is lifted out of the water and underwater seals are not required, allowing the Ashbrook decanter to make use of stainless steel V-notch weirs to significantly enhance flow control.  Additionally, the Ashbrook design eliminates the need for expensive, actuated decant valves.  A superior quality effluent is produced by lowering the v-notched weir into the water surface, starting with a slow, controlled decant rate which minimizes the disturbance of settled sludge.  The weir position is adjusted by simultaneously operating three screw jacks with a single motor, which ensures proper control of the flow rate.  The depth adjustment of the weir is controlled using electric actuators only, which allows for superior flow control.