During biodegradation processes in Wastewater Treatment Plants (WWTP), bacteria play an important role, and associations of bacteria with microalgae have the potential to remediate wastewater by reducing pollutants. This work aimed to identify bacteria present in wastewater and to analyze their interaction with C. vulgaris to favor their phytoremediation. The physicochemical and microbiological characterization of the wastewater from the Alseseca-Sur WWTP was carried out, identifying the bacterial isolates, a phytoremediation treatment was performed with C. vulgaris and wastewater as a culture medium, quantifying the proliferation of C. vulgaris in the supplemented culture medium and the wastewater. The physicochemical parameters decreased after phytoremediation, the algae-bacteria system caused a decrease in COD due to its application in symbiosis; Pseudomonas sp. prevailed with 75%; C. vulgaris showed optimal growth when wastewater was used as culture medium, inoculating C. vulgaris in wastewater at 100%, 174 cells/mL were quantified compared to 24 cells/mL of C. vulgaris with bold medium plus drinking water. The phytoremediation process in conjunction with the bacterial load effluent from the Alseseca-Sur WWTP showed a decrease in the values of physicochemical parameters; in addition to increasing the number of cells/mL of C. vulgaris using water from the effluent of the Alseseca-Sur WWTP as a culture medium.