“…In recent years, alternative treatment methods have been investigated to treat wastewater with high NH + 4 -N concentration (Akgul, Aktan, Yapsakli, & Mertoglu, 2013;Badia, Kim, Nakhla, & Ray, 2019;Li, Huang, Ruan, Ren, & Miao, 2014;Wang et al, 2018;Zhang, Zhou, Han, & Zhang, 2014). Among these methods, the combined processes of complete nitritation (CN) (or partial nitritation) and anaerobic ammonium oxidation (ANAMMOX) have shown excellent nitrogen removal efficiency for ammonia-rich wastewater (Almeida et al, 2018;Li, Zhou, et al, 2014). Generally, nitritation precedes ANAMMOX as a pretreatment step to supply nitrite nitrogen (NO − 2 -N) to ANAMMOX (Wang et al, 2018).…”