Chen, C.C.ChenXu, X.-J.X.-J.XuLee, D.-J.D.-J.LeeDUU-JONG LEE2021-02-042021-02-042020Chen, C.;Xu, X.-J.;Lee, D.-J.https://www.scopus.com/inward/record.url?eid=2-s2.0-85094575147&partnerID=40&md5=f435fc4b45cf6c4292636a44dbba789chttps://scholars.lib.ntu.edu.tw/handle/123456789/547673Massive quantity of industrial wastewater is produced annually, and biological nitrogen recovery from these streams is a promising and sustainable measure to avoid nitrogen burdens on the environment and to provide novel resources to be reused in societies. This chapter discusses a few processes (bioelectrochemical systems, salt crystallization, and membrane technologies) to recover nitrogen in the form of microbial protein, organic fertilizers from microalgae, nitrous oxide, or ammonium. The microbial protein production has a low water and land demand, and the produced protein can be used as high-quality feeds for animals, or as supplement protein for humans. The organic fertilizer from microalgae may be applied in agriculture for growth of food crops. The recovered nitrous oxide can act as an effective oxidant for combustion fuels. The recovered ammonium can also be used for fertilizer production. Challenges and perspectives of the biological nitrogen recovery are concluded at the end of this chapter. © 2020 Elsevier B.V. All rights reserved.Bioelectrochemical system; Membrane technology; Microalgae; Microbial protein; Nitrogen recovery; Nitrous oxide[SDGs]SDG2[SDGs]SDG6[SDGs]SDG9book part10.1016/B978-0-444-64321-6.00007-02-s2.0-85094575147