Hydrodynamic Criteria to Design Water Recirculation Systems for Aquaculture

Closed water recirculation systems (WRS) have been developed for aquaculture in order to more efficiently use water. In terms of water quality and biological studies, the hydrodynamics of recirculation tanks is an aspect that has been least studied. The work herein describes an experimental investigation carried out with a reduced-scale plexiglass model of these tanks. Fish food was used in one tank in which the resulting flocs served as tracers to determine sedimentation characteristics. Using optical techniques 3/4particle image velocimetry (PIV)3/4 it was possible to determine the optimal distribution of diffusers to obtain different velocities in the tank in order to facilitate the flocculation and sedimentation processes. A design for a central settling basin is also proposed based on the characterization of the flocs and their hydrodynamic behavior, particularly the fall velocity. Particle trace velocimetry (PTV) was used to calculate the fall velocity of the flocs. The experimental results enabled calibrating a mathematical model for fall velocities of flocs.