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

Lanlan Hu; Xiaohui Cheng; Guangxia Qi; Min Zheng; Yan Dang; Jiyun Li; Kangning Xu

doi:10.3389/fmicb.2022.918634

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

Front Microbiol. 2022 Jun 27:13:918634. doi: 10.3389/fmicb.2022.918634. eCollection 2022.

Authors

Lanlan Hu¹, Xiaohui Cheng¹, Guangxia Qi², Min Zheng³, Yan Dang¹, Jiyun Li⁴, Kangning Xu¹

Affiliations

¹ Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, China.
² Key Laboratory of Cleaner Production and Integrated Resource Utilization of China National Light Industry, Beijing Technology and Business University, Beijing, China.
³ Australian Centre for Water and Environmental Biotechnology, The University of Queensland, St Lucia, QLD, Australia.
⁴ School of Environment, Tsinghua University, Beijing, China.

Abstract

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 Fe₂O₃ and proposed a novel approach to reduce the Fe(III) consumption. The results showed that anammox genera Candidatus Brocadia and Candidatus Kuenenia in the seed anammox sludge significantly decreased after cultivation. The formation of N₂ 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.

Keywords: Feammox; ammonium removal; anammox; iron reduction; specific activity.