The economical and efficient removal of nickel nitrate from industrial wastewater remains a challenge. Herein, we developed an innovative electrochemical membrane filtration system that used a periodic polarity reversal process to adjust the acid-base environment near membrane interface for the recovery of nickel (II) and ammonia. The Ru based electrocatalytic layer could boost the selective reduction of nitrate to ammonia by generating atomic hydrogen, resulting in the precipitation of Ni2+ by the increasing pH at the membrane interface. Then, the precipitation of Ni(OH)2 could be effectively stripped and collected under the periodic polarity reversal process. In-situ interfacial measurements demonstrated that the polarity reversal process enabled a reversible transformation between strongly acidic (pH < 2) and alkaline (pH > 13) environments within a 200 µm range at the membrane interface. In continuous flow operation treating real industrial wastewater containing 96.7 mg-N L−1 nitrate and 135.0 mg L−1 Ni2+, the system demonstrated the capability to achieve 92.5 ± 2.6 % nitrate removal (with a recovery efficiency of 15.1 ± 1.9 g-NH3 kWh−1) and 99.7 ± 0.1 % Ni²⁺ removal (with a recovery efficiency of 24.9 ± 2.4 g-Ni kWh−1). Additionally, the specific treatment cost was approximately $0.17 m−3, attributed to the recovery of Ni(OH)₂ and ammonia. Furthermore, this system could deliver a significant economic benefit ($1.64 per m3) for treating a high concentration real wastewater (331.5 mg-N L−1 nitrate and 1496.3 mg L−1 Ni2+), outperforming traditional alkali precipitation and biological nitrification/denitrification processes. Overall, our study presents an economical and sustainable method for recovering valuable chemicals from wastewater containing heavy metals and inorganic nitrogen, potentially advancing cost-effective water treatment technologies.

中文翻译：

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一种新型电化学膜过滤系统，通过周期性极性反转操作，从含硝酸镍的工业废水中高效回收资源


经济有效地从工业废水中去除硝酸镍仍然是一个挑战。在此，我们开发了一种创新的电化学膜过滤系统，该系统使用周期性极性反转过程来调整膜界面附近的酸碱环境，以回收镍 （II） 和氨。Ru 基电催化层可以通过生成原子氢来促进硝酸盐选择性还原为氨，从而通过膜界面处 pH 值的增加沉淀 Ni2+。然后，在周期性极性反转过程中，Ni（OH）2 的沉淀可以被有效地剥离和收集。原位界面测量表明，极性反转过程使膜界面处 200 μm 范围内的强酸性 （pH < 2） 和碱性 （pH > 13） 环境之间发生可逆转变。在处理含有 96.7 mg-N L-1 硝酸盐和 135.0 mg L-1 Ni2+ 的实际工业废水的连续流操作中，该系统表现出能够实现 92.5 ± 2.6% 的硝酸盐去除率（回收效率为 15.1 ± 1.9 g-NH3 kWh-1）和 99.7 ± 0.1 % Ni²⁺ 去除率（回收效率为 24.9 ± 2.4 g-Ni kWh-1）。此外，归因于 Ni（OH）₂ 和氨的回收，特定处理成本约为 0.17 m-3。此外，该系统可以为处理高浓度真实废水（331.5 mg-N L-1 硝酸盐和 1496.3 mg L-1 Ni2+）带来显着的经济效益（每立方米 1.64 美元），优于传统的碱沉淀和生物硝化/反硝化过程。 总体而言，我们的研究提出了一种经济且可持续的方法，用于从含有重金属和无机氮的废水中回收有价值的化学品，从而有可能推动具有成本效益的水处理技术。