Several studies have explored nitrogen recovery from waste streams, focusing on technologies and approaches like electrochemical processes and membrane separation. However, these approaches need to become economically feasible and reliable. The feasibility of recovery processes is strongly influenced by the concentration of nitrogen, which is an important technical challenge in nitrogen recovery. Biological approaches, such as the cultivation of microalgae as well as constructed wetlands, are in focus for addressing nitrogen concentration steps. These approaches allow the conversion of nitrogen compounds into proteins for various applications. The aim of this study was not to review treatment processes to avoid negative environmental consequences but to highlight technologies that allow the concentration, recovery, and circulation of nitrogen compounds.