FLOW-THROUGH TESTS FOR THE DESIGN OF A NEW FLOCCULATION SYSTEM

A pilot-plant flocculation system with a flow capacity of 600 m(3)/h, was evaluated hydraulically using an alkali (NaOH) as a tracer measure d with pH probes. A series of four tanks, each containing a stirrer, p rovided sequentially lower G values to ensure taper flocculation. The flow through each tank, and a transfer channel, required plug flow con ditions. From a high steady-state plateau of pH 11, a cut-off of alkal i dosing led to a decrease of pH as the tracer was displaced by the fl ow. Interpretation of the pH decrease allowed evaluation of the flowth rough conditions, and how these could be improved by adjustments of we irs, slots, baffles and stirrers.