Mixing Characteristics of a High-Rate Algae Pond

In order to define an appropriate mathematical model for the flow and mixing characteristics of a high-rate algae pond, impulse-response tests were carried out on an experimental pond located at Ein Karem, near Jerusalem, at Reynolds number = 10 5, and on two scale models of the same pond, at 2 000 < Re < 20 000. Each pond consisted of a continuous rectangular channel with seven 180° bends, and was mechanically recirculated. It was demonstrated that this type of pond is well characterised by either a dispersed-plug-flow model with dispersion numbers in the range 0,003 to 0,017, or by a tanks-in-series model. Dispersion intensities were correlated by a modified dispersion number for depth: width ratios in the range 0,18 to 0,76.