epa09471322 People walk past a ?Liquid3? urban photo-bioreactor developed and designed by the University of Belgrade Institute for Multidisciplinary Research in Belgrade, Serbia, 16 September 2021. An urban photo-bioreactor uses the power of micro algae to efficiently remove carbon dioxide (CO2) and produces dioxygen (O2) and biomass, effectively replacing one adult tree or 200 square meters of lawn, representing an alternative sustainable concept of greening of urban environments that show limited space and heavy pollution. EPA/ANDREJ CUKIC
