This study aimed to investigate the physiological and biochemical responses of filamentous microalga Tribonema minus to different Na2SeO3 concentrations and its selenium absorption and metabolism to evaluate the potential in treating selenium-containing wastewater. The results showed that low Na2SeO3 concentrations promoted growth by increasing chlorophyll content and antioxidant capacity, whereas high concentrations caused oxidative damage. Although Na2SeO3 exposure reduced lipid accumulation compared with the control, it significantly increased carbohydrate, soluble sugar, and protein conten...