EVALUATING BUOYANT COARSE MEDIA FLOCCULATION

A new type of coarse media flocculator, using buoyant media instead of the heavier gravel in order to facilitate cleaning, was evaluated in laboratory and field studies. The results indicate that a two-stage bu oyant coarse media (BCM) flocculator provided effective treatment at h igher loading rates and shorter residence times than are typically emp loyed in designing mechanical flocculators. Source-water quality and c oagulant chemistry directly influenced flocculator performance and dic tated the type of flocculator configuration selected. Tapering velocit y gradients in the first-stage flocculator enhanced performance. The a uthors recommend that additional studies be performed to develop relia ble design and operating criteria for full-scale BCM flocculators.