Improvements in rotating biological contactors, and a method for their manufacture.

摘要

A rotating biological contactor for sewage effluent treatment comprises a semi-buoyant rotor (1) mounted on a shaft (3) including a surface (9,10) available as a biomass growth substrate. The rotor is defined by a drum (2) enclosing a plurality of coaxially mounted discs (9) each sandwiching therebetween a series of closely spaced spiral vanes (10) defining said growth substrate. Effluent to be treated is held in a tank (20) in which the rotor is partly submerged, and enters the drum (2) through inlets (7) to pass around the outer periphery of the discs (9) via a passageway (13) as the rotor rotates. The vanes (10) pick up the effluent which is gradually lifted to a duct in the axial region of the rotor communicating between adjacent discs leading to an outlet (8). The rotor may be made of thin flexible sheet material such as glass reinforced plastics, wherein strips of the material are placed edgewise onto a base template (30) to define a spiral pattern of individual vanes (10) emanating from a central hub region (38) which are then adhered to a circular disc (9) of the same material, characterised by clamping the template (34) with the vanes (10) against the disc (9) with a coating of curable adhesive therebetween, supporting the clamped assembly in a jig (30), rotating the clamped assembly if necessary so as to ensure that the vanes face upwards but maintaining the template substantially horizontal, and releasing the finished rotor construction from the jig when curing of the adhesive is complete.