Beijing Key Laboratory for Source Control Technology of Water Pollution, College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China.
Water Quality Testing Center, Beijing Drainage Water Environment Development Co., Ltd., Beijing 100022, China.
Int J Environ Res Public Health. 2022 Mar 10;19(6):3270. doi: 10.3390/ijerph19063270.
NH is often produced during the electro-reduction of NO, which results in inadequate total nitrogen (TN) removal during advanced sewage treatment. In this study, the electro-reduction byproduct NH was oxidized and removed using sulfate radical (SO)-based advanced oxidation. Persulfate (PS) was activated by electrocatalysis, using Co/AC-AB particle electrodes to produce SO. Results showed that when the influent concentration of NO-N was 20 mg/L, a PS dosage of 5.0 mM could completely oxidize NH at 0.1 A (nondetectable in effluent) reducing the TN concentration from 9.22 to 0.55 mg/L. The presence of coexisting PO, CO and humic acid suppressed the oxidation and removal of NH. Electron spin resonance (ESR) spectra and quenching experiments revealed SO as the dominant radical in the process of indirect NH oxidation, while •OH radicals only had an assisting role, and the surface accumulated free radicals were responsible for the indirect oxidation of NH. Cyclic voltammetry (CV) curves indicated that NO was primarily reduced via atomic H*-mediated indirect reduction. Therefore, the activation of PS using Co/AC-AB particle electrodes might be a promising alternative method for oxidizing byproduct NH in the electro-reduction of NO and reduce TN concentration in advanced sewage treatment.
NH 在 NO 的电还原过程中经常产生，这导致在高级污水处理过程中总氮（TN）的去除不足。在这项研究中，使用基于硫酸根自由基（SO）的高级氧化法氧化和去除电还原副产物 NH。过硫酸盐（PS）通过电催化激活，使用 Co/AC-AB 颗粒电极产生 SO。结果表明，当进水 NO-N 浓度为 20mg/L 时，PS 剂量为 5.0mM 可以完全氧化 NH（出水中无法检出），将 TN 浓度从 9.22mg/L 降低至 0.55mg/L。共存的 PO、CO 和腐殖酸会抑制 NH 的氧化和去除。电子顺磁共振（ESR）图谱和猝灭实验表明，SO 是间接氧化 NH 过程中的主要自由基，而 •OH 自由基仅起辅助作用，表面积累的自由基负责 NH 的间接氧化。循环伏安（CV）曲线表明，NO 主要通过原子 H*-介导的间接还原进行还原。因此，使用 Co/AC-AB 颗粒电极激活 PS 可能是一种有前途的替代方法，可以在 NO 的电还原中氧化副产物 NH，并降低高级污水处理中的 TN 浓度。
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