The project stands for a brand new biotechnological solution for air purification and CO2 emission reduction in urban areas (at the source of emissions). The concept combines the technology of large photo-bioreactor systems that are used in the processing of industrial exhaust fumes (such systems do not fit into urban environments given their size and design), with compact models of photo-bioreactors that are used for commercial production of microalgae biomass and specific products, in this way combining the energy sector with agriculture. This would be a pioneering venture in Serbia, given that it can create a momentum for microalgae production in commercial purposes. The concept of LIQUID3 photo-bioreactor is aimed at initiating the development of a new multi-component communal service that combines greening of areas that are inaccessible to traditional greening methods (trees and lawns) with urban agriculture.