Environmental Science and New Energy Technology Research Center, Tsinghua-Berkeley Shenzhen Institute, Tsinghua University, Shenzhen 518055, China.
Shenzhen Engineering Research Laboratory for Sludge and Food Waste Treatment and Resource Recovery, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China.
Environ Sci Technol. 2023 Jun 13;57(23):8828-8838. doi: 10.1021/acs.est.3c02286. Epub 2023 May 29.
Flow-electrode capacitive deionization (FCDI) is a promising electromembrane technology for wastewater treatment and materials recovery. In this study, we used low-cost Na-modified zeolite (Na-zeolite) to prepare a composite flow-electrode (FE) suspension with a small amount of highly conductive carbon black (CB) to remove and recover NH from synthetic and actual wastewater (200 mg-N/L). Compared with conventional activated carbon (AC), the Na-zeolite electrode exhibited a 56.2-88.5% decrease in liquid-phase NH concentration in the FE suspension due to its higher NH adsorption capacity (6.0 vs. 0.2 mg-N/g). The resulting enhancement of NH diffusion to the electrode chamber contributed to the improved performance of FCDI under both constant current (CC) and constant voltage (CV) conditions. The addition of CB to the FE suspension increased the conductivity and facilitated Na-zeolite charging for NH electrosorption, especially in CV mode. NH-rich zeolite can be easily separated by sedimentation from CB in the FE suspension, producing a soil conditioner with a high N-fertilizer content suitable for soil improvement and agricultural applications. Overall, our study demonstrates that the novel Na-zeolite-based FCDI can be developed as an effective wastewater treatment technology for both NH removal and recovery as a valuable fertilizer resource.
流动电极电容去离子（FCDI）是一种很有前途的电膜技术，可用于处理废水和回收材料。在这项研究中，我们使用低成本的 Na 改性沸石（Na-沸石）来制备一种复合流动电极（FE）悬浮液，其中少量高导电性的炭黑（CB）可去除和回收来自合成和实际废水（200mg-N/L）中的 NH。与传统的活性炭（AC）相比，由于 Na-沸石电极具有更高的 NH 吸附容量（6.0 与 0.2mg-N/g），因此在 FE 悬浮液中，液相 NH 浓度降低了 56.2-88.5%。这使得 NH 在电极室内的扩散增强，从而在恒流（CC）和恒压（CV）条件下提高了 FCDI 的性能。在 FE 悬浮液中添加 CB 可提高导电性，并促进 NH 电吸附时的 Na-沸石充电，尤其是在 CV 模式下。富含 NH 的沸石可通过沉降从 FE 悬浮液中的 CB 中轻易分离出来，产生一种高氮肥料含量的土壤改良剂，适合土壤改良和农业应用。总的来说，我们的研究表明，新型的基于 Na-沸石的 FCDI 可以开发为一种有效的废水处理技术，既能去除 NH，又能回收作为有价值的肥料资源。
