LAUSR

Abstract Ammonia recovery from wastewater gained increasing attention worldwide with the growing world population. However, subsequent treatment of the recovered ammonia was still complex and challenging. Therefore, a proof of concept approach by designing a novel stacked flow electrode capacitive deionization (FCDI) cell was presented in this study, to achieve ammonia recovery and generation of value-added products. Ammonium sulfate was generated successfully in the product chamber with K2SO4 worked as an additive. To avoid the influence of the co-existing ions, the effect of a monovalent cation-selective exchange membrane (M-CEM) was emphasized in the stacked FCDI cell. Compared with the standard cation exchange membrane (S-CEM), the product purity increased from around 50% to 85%, while the ratio of NH4+ towards co-existing cations increased almost 2 times by using M-CEM. To illustrate the reasons for the enhanced ion selectivity, the characterizations of both membranes were conducted by Electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FTIR) and X-ray diffractometry (XRD). Therefore, this study indicated that the novel design and efficient operation of the stacked FCDI reactor is an alternative way for ammonia recovery and generation as value-added products, as well as a possible approach to scaling up.