Optimization in the design of a wastewater treatment system integrated by three stabilization lagoon

Article presents a mathematical model for the optimization of a lagoon system composed of three lagoons: anaerobic, facultative and maturation. The mathematical model of optimization aims at minimizing the area occupied by the lagoon system, and has as restrictions the water quality in the effluent: biochemical oxygen demand and the number of fecal coliforms; In addition, the dispersion (greater than or equal to 0.05) is restricted, in order to favor the dispersed flow in the facultative lagoon and the ripening lagoon. The changing variables in the optimization model are the following: retention time and number of screens, both facultative and maturation lagoons, and the long wide ratio for the anaerobic lagoon. A lagoon system design was performed, then the proposed mathematical model was applied. The results show a decrease of the area of 15.16 percent. The two studies comply with maximum permissible discharge limits, according to NOM-SEMARNAT-1996: quality of wastewater treated for discharge to receiving bodies.