Air pollution is regarded as a menace that deteriorates the quality of life for urban residents. Deforestation resulting from urbanization has reduced the absorption of greenhouse gases and pollutants by trees. Consequently, the concept of the "Liquid Tree" has emerged in recent scientific research. The "Liquid Tree" is a photo-bioreactor designed in Serbia, housing green microalgae capable of capturing and sequestering carbon dioxide from the atmosphere. It conducts photosynthesis to release pure oxygen, thereby enhancing air quality. In addition to air purification, it treats wastewater and promotes greenery in densely populated urban areas. This popular article summarizes the operational principles and potential applications of the Liquid Tree.