Cheng Xiaohui, Hu Lanlan, Liu Tao, Cheng Xiang, Li Jiyun, Xu Kangning, Zheng Min
Beijing Key Lab for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing, 100083, China.
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, 999077, China.
Water Res X. 2024 Dec 3;27:100292. doi: 10.1016/j.wroa.2024.100292. eCollection 2025 May 1.
Anaerobic ammonium oxidation coupled with Fe(III) reduction (Feammox) is an essential process in the geochemical iron and nitrogen cycling. This study explores Feammox-based nitrogen removal in a continuous laboratory up-flow bioreactor stimulated by intermittently adding 5 mM Fe(OH) at intervals of approximately two months. The feed was synthetic wastewater with a relatively low ammonium concentration (∼100 mg N/L), yet without organic carbon in order to test its autotrophic nitrogen removal performance. The operation of this system showed the achievement of high-level ammonium and total nitrogen removal efficiency (∼97% and ∼90% on average, respectively) within four months of operation, along with a relatively practical rate of ∼50 mg N/(L·d). The demand of Fe(Ⅲ) for ammonium removal during the whole bioreactor operation was estimated to be only 0.033, two orders of magnitude less than that calculated based on the Feammox reaction producing nitrogen gas. A series of assays on Fe(II) oxidation with different oxidants (O, NO and NO ) in abiotic and biotic batch tests further revealed an important role of Fe(II) oxidation processes, likely driven by microbial nitrate reduction and chemical oxygen reduction, in assisting the regeneration of Fe(III) for continuous Feammox-based nitrogen removal. This work demonstrates that Feammox-based autotrophic nitrogen conversion is a potential option for future wastewater treatment.
厌氧氨氧化耦合铁（III）还原（铁氨氧化）是地球化学中铁和氮循环的一个重要过程。本研究探索了在连续实验室上流生物反应器中基于铁氨氧化的脱氮过程，该反应器通过每隔约两个月间歇添加5 mM氢氧化铁来刺激。进料为合成废水，铵浓度相对较低（约100 mg N/L），但不含有机碳，以测试其自养脱氮性能。该系统运行表明，在运行四个月内实现了高水平的铵和总氮去除效率（平均分别约为97%和90%），以及约50 mg N/(L·d)的相对实用速率。整个生物反应器运行过程中去除铵所需的铁（Ⅲ）估计仅为0.033，比基于产生氮气的铁氨氧化反应计算的值低两个数量级。在非生物和生物批次试验中，用不同氧化剂（氧气、硝酸盐和亚硝酸盐）对亚铁氧化进行的一系列测定进一步揭示了亚铁氧化过程的重要作用，这可能是由微生物硝酸盐还原和化学需氧量还原驱动的，有助于基于铁氨氧化的连续脱氮过程中铁（III）的再生。这项工作表明，基于铁氨氧化的自养氮转化是未来废水处理的一个潜在选择。
