Study of the internal hydrodynamics in three facultative ponds of two municipal WSPS in Spain

The hydraulic performances of three facultative ponds, two of the Cieza and one of the Lorquí–Ceutí joint municipal wastewater stabilization ponds systems, were studied. The ponds of Cieza have a maximum capacity of 16,500 m3 (F.1) and 32,000 m3 (F.2), and both have a maximum depth of 1.6 m. The pond of Lorquí–Ceutí have a maximum capacity of 27,000 m3 and a maximum depth of 1.8 m. A dye tracer, sulforhodamine B, was injected with the feed flow of each one facultative ponds. In the course of time, samples from within and at the outlet of every system were taken. The data obtained prove that the hydrodynamic behavior of the ponds is similar to a perfectly mixed tank reactor. The average real residence times were also determined. When these were compared to ponds, considered ideal perfectly mixed tank reactors, a high level of coincidence was noted. It was also observed that the hydrodynamics of the ponds presented virtually no flow anomalies.