Today, there are several sustainable wastewater purification techniques that meet the demand for the reuse of treated water and at the same time allow us to provide a new value to the biomass used in the purification. This technique is the high rate algal pond, which is a very advantageous lagoon method. A model station was recently installed in Tunisia at the Superior agronomic institute (SAI) of Chott-Mariam, and the interest of our research is to study its purification performance, to optimize it by using the modeling tool so that we can provide a reusable water for irrigation and agriculture, as well as to valorize the algal biomass produced in a very large quantities by the pond. This research project aims to increase investments in projects including sustainable purification techniques in countries such as Tunisia where the recurring water deficit and the demand for reuse of treated wastewater are particularly present. Our research aims to optimize the treatment process, by applying the modeling tool, which is used as a decision making and sizing tool for the management of this type of treatment system in Tunisia. We are in the process of calibrating a mathematical model of the algal pond by using a series of experimental measurements which are carried out on the experimental station, while allowing the integrated management of effluents and algae produced. Indeed, this technique is based on the symbiotic interaction between heterotrophic bacteria and algae (Oswald, 1978; Santiago 2013) allowing the elimination of the organic load and nutrients (phosphorus and nitrogen), after the step of purification, the algae thus produced in large quantities will undergo a recovery step by bio-flocculation and will be used as bio-fertilizer and as animal feed, where the added value of the project comes from.