Exploring the potential of a novel alternating current stimulated iron‑carbon anammox process: A new horizon for nitrogen removal
Fei Xie, Bowei Zhao, Ji Li, Philip Antwi, Yuan Li, Xiuping Yue
Abstract
This study explored a novel alternating current (AC) stimulation approach to enhance the nitrogen removal efficiency of an iron‑carbon based anammox (Fe C anammox) system. In the preliminary experiment, the TN removal efficiency of the AC stimulated system was 8.06 % higher than that of a DC simulated system in same current densities of 0.25 mA/cm 2 . Gene expression analysis revealed that the AC-stimulated system, where, compared with the anammox system alone, the expression of HZS, HDH, Nar G, Nir S, Nor B and Nos Z increased by 1.81, 2.50, 1.64, 0.23, 1.15 and 1.27 times, respectively. In the continuous experiment, the TN removal rate increased from 60.13 % to 84.34 % after AC stimulation, and the working time of the Fe C materials increased to 20 days. An analysis of the mechanism revealed that the parallel connection between the capacitive reactance and filler resistance in AC might reduce the internal resistance of the system, thereby improving the actual current density received by local microorganisms, and achieving a better strengthening effect.