Accelerated aggregation kinetics and hydrodynamic floc separation for municipal water treatment

Abstract

This paper reports on improvements to aggregation kinetics of colloidal particles in municipal water treatment by injection of mature floc as seed for rapid floc formation. The larger mature floc promotes aggregation of the much smaller entities resulting in much shorter aggregation time. A high throughput, continuous flow, hydrodynamic separation for membrane-less, size-selective particulate extraction has recently been reported. In addition to traditional centrifugal effects, the transverse flow driven by centrifugal force created in spiral flow channels result in transverse migration of micron-sized neutrally buoyant suspensions which are focused into a band and then diverted for extraction [1,2]. The combined effects of the spiral mixer to generate denser and uniformly sized pin floc, the mature floc seeding to rapidly grow floc, and the immediate spiral separation of the floc allows for elimination of flocculation and sedimentation steps, resulting in significant savings in reduced land and chemical cost, and faster processing time from raw to finished water [3,4].