Flocculator design - The case for vorticity
John Bridgeman, Davide Dapelo
Abstract
Traditionally, flocculator design has been based on empiricism and guided by average velocity gradient and Camp number (being the product of average velocity gradient and flocculation time) values. Here, we analyze existing laboratory and full-scale datasets under a novel perspective, demonstrating that the Camp number is not necessarily a useful indicator of flocculator performance when considering floc size or strength. At the same time, we identify a previously overlooked link between the volume-weighted vorticity and both floc size and floc strength. It is concluded that vorticity may be a useful parameter in flocculator design and determining optimum operating conditions for new and existing facilities. A protocol for the assessment of existing flocculation facilities and the design and operation of new ones is provided, based on volume-weighted vorticity rather than Camp Number and average velocity gradient.