Interaction of Coagulation-Flocculation with Separation Processes

Interaction between aggregate formation and the liquid-solid separation process was explored by systematic investigation of the sedimentation or flotation of coagulated suspensions with various scaled-down continuous-flow separation reactors. Suspensions were coagulated under systematically varied chemical and physical boundary conditions. The pattern of flow (determined by the geometry of the reactor and inflow-outflow configuration) had a marked effect on the removal of aggregated suspensions. Flocs formed under less readily aggregating conditions were generally removed to a lower degree in sedimentation units than those formed with metal salts and polymers. Compensation for these disadvantages is possible through improved tank design or use of flotation. However, suspensions flocculated with polymer alone appear less suitable for flotation.