Utilizing Tetradesmus obliquus for Phycoremediation Enhanced Nitrogen and Phosphorus Removal in Urban Wastewater Treatment

Microalgae can scavenge pollutants through a process called phycoremediation, which involves the removal or biotransformation of pollutants in wastewater and gaseous media. Algae must grow rapidly, tolerate seasonal and diurnal variations, and form aggregates easily. In this study, the phosphorus and nitrogen removal capacity of the microalga Tetradesmus obliquus, isolated from urban water bodies, was evaluated and its cultivation was proposed as an alternative for tertiary treatment of urban effluents. The inoculum was placed in a bioreactor at 25 ºC with natural lighting for 21 days in modified Bold Basal Medium (BBM). The experiment included a control group (BBM) and a treatment with distilled water (AD) and increasing concentrations of urban effluent (12.5%, 25%, 50%, and 100%), inoculated with 8.8x105 cells/ml of biomass. The treatments were carried out in triplicate for 15 days. pH, dissolved oxygen (DO), conductivity, NO3- and PO4-3 concentrations, and biological variables such as cell count and optical density were determined. Tetradesmus obliquus showed efficiency in removing phosphates and nitrates. Maximum efficiency was shown after 15 days of treatment with 100% effluent, removing 22.92% of phosphates and 65.66% of nitrates.