A novel cost-effective flow-electrode capacitive deionization unit combined with a hydrophobic gas-permeable hollow fiber membrane contactor (designated “CapAmm”) is described here and used for efficient recovery of ammonia from dilute synthetic wastewaters. During operation, ammonia migrates across a cation exchange membrane and selectively accumulates in the cathode chamber of a flow electrode followed by transformation to dissolved NH₃ with subsequent stripping via a membrane contactor and recovery as ammonium sulfate. Our results demonstrate that the CapAmm process can achieve an ammonia removal efficiency of ∼90% and a recovery efficiency of ∼60%. At current densities of 5.8 and 11.5 A m^–2 (normalized by the effective cation exchange membrane area) and a hydraulic retention time of 1.48 min, the energies required for ammonia recovery were 9.9 and 21.1 kWh (kg of N)⁻¹, respectively, with these values being comparable with those of other similar electrochemical ammonia recovery systems. These findings suggest that the CapAmm technology described here has the potential for the dual purposes of cost-effective salt removal and the recovery of ammonia from wastewaters, with greater stability, better flexibility, and greater energy efficiency compared to those of other methods.

中文翻译：

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电容膜汽提法从稀废水中回收氨（CapAmm）

本文介绍了一种新型的具有成本效益的流电极电容去离子装置，该装置与疏水性透气中空纤维膜接触器（称为“ CapAmm”）相结合，可用于从稀合成废水中高效回收氨。在操作过程中，氨迁移穿过阳离子交换膜并选择性地积聚在流动电极的阴极室中，然后转化为溶解的NH ₃，随后通过膜接触器进行汽提，并以硫酸铵的形式回收。我们的结果表明，CapAmm工艺可实现约90％的氨去除率和约60％的回收率。在电流密度为5.8和11.5 A m ^–2时（通过有效的阳离子交换膜面积进行归一化）和1.48分钟的水力停留时间，氨气回收所需的能量分别为9.9和21.1 kWh（千克N）^-1，这些值可与其他同类产品相比电化学氨回收系统。这些发现表明，与其他方法相比，此处介绍的CapAmm技术具有实现成本有效的除盐和从废水中回收氨的双重目的的潜力，具有更高的稳定性，更好的灵活性和更高的能源效率。