Buoyant coarse media flocculator

Abstract

A coarse media flocculator utilizes buoyant media restrained against upward movement in a vertical chamber whose cross-sectional area increases uniformly in the direction of flow, thereby providing a uniformly tapering velocity gradient. The height of the media restrainer within the chamber can be adjusted, thereby changing the depth and cross-sectional characteristics of the media bed within the tapered chamber. The velocity gradients of the flocculator can thus be changed independent of flow. A washwater piping grid with downwardly pointed jet spray nozzles is positioned within the media bed for cleaning. The height of the media bed can be adjusted by changing the position of the media restrainer or by changing the liquid level within the chamber, thus changing that part of the media bed where the jet spray is concentrated. In one embodiment, the restrainer is disposed within an area of the chamber above the tapered portion having a uniform cross-section. This arrangement facilitates adjustment of the position of the restrainer and also facilitates cleaning by allowing the restrainer to be repeatedly pushed downwardly, thereby pulsating the media bed. In a second embodiment, a two-piece restrainer is disposed within the tapered portion of the chamber and is sectional and consequent flocculation parameters to be adjusted in both upper and lower portions of the media bed.