Promoting nitrogen removal during Fe(III) reduction coupled to anaerobic ammonium oxidation (Feammox) by adding anthraquinone-2,6-disulfonate (AQDS)
2019
Yang, Yafei | Peng, Hong | Niu, Junfeng | Zhao, Zhiqiang | Zhang, Yaobin
Feammox, i.e., Fe(III) reduction coupled to anaerobic ammonium oxidation, is a potential alternative to ammonium removal in natural and artificial ecosystems. However, the efficiency of Feammox is quite low to restrain its practical application in wastewater/solid disposal. In this study, three batch experiments, including control (Fe₂O₃/AQDS-free), Fe₂O₃ group (25 mM Fe₂O₃ only) and AQDS-Fe₂O₃ group (25 mM Fe₂O₃ and 0.6 mM AQDS), were conducted in 200 mL serum vials to explore whether AQDS can promote Feammox. Results showed that the nitrogen removal efficiency of the AQDS-Fe₂O₃ group was 82.6%, compared with 64.3% of the Fe₂O₃ group and 46.0% in the control. AH₂QDS, the reduced state of AQDS, was detected in the AQDS-Fe₂O₃ group. Another experiment indicated that AH₂QDS was oxidized back to AQDS by Fe₂O₃. These results suggested that AQDS/AH₂QDS had been serving as electron shuttles between ammonium and Fe₂O₃ to successively forward the oxidation of NH₄⁺. X-ray diffraction analysis showed that new Fe(III) species were found in the systems, implying that a Fe(II)/Fe(III) cycle also occurred. In agreement, both iron-reducing and oxidizing bacteria were detected in the systems.
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