Stimulant sensitive flocculation and consolidation for improved solid/liquid separation.

A novel method of flocculation resulting in both rapid sedimentation and low sediment moisture is described. It relies on changing the inter-particle forces from repulsive to attractive (aggregation and fast settling results) and then back to repulsive (densification of sediment then occurs). The change in inter-particle force is controlled by a stimulus such as pH or temperature. The technique is demonstrated without polymer using the isoelectric point and pH as the stimulus. The polyelectrolyte chitosan produces faster sedimentation and clearer supernatants as a pH sensitive flocculant. Methylcellulose is an effective temperature sensitive flocculant. The sediment bed volumes can be reduced by between 10 and 45% depending upon the conditions which, as yet, have not been fully optimized.