AUTHOR=Hu Lanlan , Cheng Xiaohui , Qi Guangxia , Zheng Min , Dang Yan , Li Jiyun , Xu Kangning 

TITLE=Achieving Ammonium Removal Through Anammox-Derived Feammox With Low Demand of Fe(III)

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.918634

DOI=10.3389/fmicb.2022.918634

ISSN=1664-302X

ABSTRACT=<p>Feammox-based nitrogen removal technology can reduce energy consumption by aeration and emission of carbon dioxide. However, the huge theoretical demand for Fe(III) becomes a challenge for the further development of Feammox. This study investigated an anammox-derived Feammox process with an intermittent dosage of Fe<sub>2</sub>O<sub>3</sub> and proposed a novel approach to reduce the Fe(III) consumption. The results showed that anammox genera <italic>Candidatus Brocadia</italic> and <italic>Candidatus Kuenenia</italic> in the seed anammox sludge significantly decreased after cultivation. The formation of N<sub>2</sub> was the dominating pathway in Feammox while that of nitrite and nitrate could be neglected. Batch tests showed that specific Feammox activity of ammonium oxidation was 1.14–9.98 mg N/(g VSS·d). The maximum removal efficiency of ammonium reached 52.3% in the bioreactor with a low dosage of Fe(III) which was only 5.8% of the theoretical demand in Feammox. The removal of ammonium was mainly achieved through Feammox, while partial nitrification/anammox also played a role due to the non-power and unintentional oxygen leakage. The super-low oxygen also responded to the low demand of Fe(III) in the bioreactor because it could trigger the cycle of Fe(III)/Fe(II) by coupling Feammox and chemical oxidation of Fe(II) to Fe(III). Therefore, anammox-derived Feammox can achieve the removal of ammonium with low Fe(III) demand at super-low oxygen.</p>