Tracer Dispersion of High Rate Settling Tanks

by Hassan M. El-Baroudi, (M.ASCE), Assoc. Prof. of Envir. Engrg.; Rensselaer Polytechnic Inst., Troy, NY,
David R. Fuller, Proj. Engr.; Wright-Pierce-Barnes-Wyman Engrs., Topsham, ME,

Serial Information: Journal of the Environmental Engineering Division, 1973, Vol. 99, Issue 3, Pg. 347-368

Document Type: Journal Paper


High-rate sedimentation tanks have different ideal hydraulic characteristics from those of the standard types. The case of tube modules installed in rectangular tanks is analyzed for ideal flow behavior. Due to the uniform diversion of flow to the tubes above, the horizontal flow velocity is reduced. The total volume of the tank can be divided into three successive zones to which certain ideal properties are assigned. These zones are the inlet, the horizontal flow, and the upward tube flow. The ideal conditions are complete mixing for the inlet zone, laminar with tapered velocity in the horizontal flow zone, and laminar flow in the tube module. For a transient tracer injected at the tank inlet, the expression for the effluent tracer concentrations, or detention time distribution, is derived based on the ideal assumptions. Experimental observations on a laboratory setup were interpreted to obtain actual functional volumes as compared to those provided by the adopted geometric configuration. Deviation from ideal behavior is measured by volumetric efficiency.

Subject Headings: Advection | Inlets (waterway) | Probe instruments | Sedimentation tanks | Fluid velocity | Laminar flow | Hydraulics | Case studies

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