The primary process carried out by the Salitre Wastewater Treatment Plant (WWTP) does not achieve a removal greater than 60% of organic matter. In this research, a biotreatment was done with the microalgae Chlorella vulgaris of the wastewater treated by this plant, prior to its dumping, with an emphasis on the removal of organic matter by chemical demand of oxygen and total suspended solids, in order to evaluate its efficiency. The incidence of microalgae in other physicochemical parameters was also evaluated. At the end of the biotreatment, the mentioned parameters were analyzed in the supernatant to compare the results of the chemical treatment performed by the Salitre WWTP (COD removal of 35.30% and 57.51% by SST) with the best biotreatment result (Sample 1: 81.80% by COD and 89.91% by SST). Finally, a better CDO removal percentage was achieved in relation to similar works by other authors.