Sedimentation is perhaps the oldest and most common water
treatment process. The principle of allowing turbidwater to settle
before it is drunk can be traced back to ancient times. In modern
times a proper understanding of sedimentation tank behavior
is essential for proper tank design and operation. Generally,
sedimentation tanks are characterized by interesting hydrodynamic
phenomena, such as density waterfalls, bottom currents
and surface return currents, and are also sensitive to temperature
fluctuations and wind effects. On the surface, a sedimentation
tank appears to be a simple phase separating device, but down
under an intricate balance of forces is present.
Many factors clearly affect the capacity and performance of a
sedimentation tank: surface and solids loading rates, tank type,
solids removal mechanism, inlet design, weir placement and
loading rate, etc. To account for them, present-day designs are
∗ Corresponding author. Tel.: +30 2310 997772; fax: +30 2310 997759.
E-mail address: karapant@chem.auth.gr (T.D. Karapantsios).
typically oversizing the settling tanks. In that way, designers
hope to cope with the poor design that is responsible for undesired
and unpredictable system disturbances, which may be of
hydraulic, biological or physico-chemical origin.