Department of Environmental Technology, Wageningen University and Research, P.O. Box 17, 6700 AA, Wageningen, the Netherlands; Department of Chemical Engineering and Polymer Science, Shahjalal University of Science and Technology, Sylhet, 3114, Bangladesh.
Department of Environmental Technology, Wageningen University and Research, P.O. Box 17, 6700 AA, Wageningen, the Netherlands.
Chemosphere. 2020 Nov;259:127491. doi: 10.1016/j.chemosphere.2020.127491. Epub 2020 Jul 1.
The reuse of cooling tower blowdown (CTBD) in the cooling tower itself requires CTBD deionization and a pre-treatment before deionization to remove organic compounds (OCs) that induce membrane fouling. This study assesses the potential of electrochemical oxidation (EO) with a boron-doped diamond (BDD) and a Ti/RuO mixed-metal oxide (MMO) anode for CTBD pre-treatment. Also, the influence of the applied current density (j), initial pH, hydrodynamic conditions, and supporting electrolyte on the process performance was evaluated. Results show that COD and TOC removal were 85 and 51%, respectively, with the BDD-anode; however, they were 50 and 12% with MMO-anode at a j-value of 8.7 mA cm and neutral pH. An increased j-value increased the COD and TOC removal; however, different pHs, hydrodynamic conditions, and the addition of supporting electrolytes had a minor impact on the removal with both anodes. Liquid chromatography-organic carbon detection analysis showed that the OC in CTBD mainly consisted of humic substances (HS). EO with the BDD-anode resulted in 35% HS mineralization, while the rest of the HS were partially oxidized into low molecular weight compounds and building blocks. However, HS mineralization was limited with the MMO-anode. The mineralization and oxidation were accompanied by the formation of organic and inorganic chlorinated species. These species increased the toxicity to Vibrio fischeri 20-fold compared to the initially low-toxic CTBD. Thus, EO with a BDD-anode is a promising pre-treatment technology for the removal of OCs before CTBD deionization, but measures to minimize the chlorinated species formation are required before its application.
将冷却塔排污（CTBD）再用于冷却塔本身需要对 CTBD 进行去离子化，并在去离子化之前进行预处理，以去除引起膜污染的有机化合物（OCs）。本研究评估了电化学氧化（EO）与掺硼金刚石（BDD）和钛/钌混合金属氧化物（MMO）阳极相结合对 CTBD 预处理的潜力。此外，还评估了施加电流密度（j）、初始 pH 值、水动力条件和支持电解质对过程性能的影响。结果表明，在 j 值为 8.7 mA cm 和中性 pH 值下，BDD 阳极的 COD 和 TOC 去除率分别为 85%和 51%；而 MMO 阳极的去除率分别为 50%和 12%。增加 j 值可以提高 COD 和 TOC 的去除率；然而，不同的 pH 值、水动力条件和支持电解质的添加对两种阳极的去除率影响较小。液相色谱-有机碳检测分析表明，CTBD 中的 OC 主要由腐殖质（HS）组成。BDD 阳极的 EO 导致 35%的 HS 矿化，而其余的 HS 部分氧化成低分子量化合物和构建块。然而，HS 的矿化在 MMO 阳极中受到限制。矿化和氧化伴随着有机和无机氯化物的形成。与最初低毒性的 CTBD 相比，这些物质使发光菌 Vibrio fischeri 的毒性增加了 20 倍。因此，BDD 阳极的 EO 是去除 CTBD 去离子化前 OCs 的一种很有前途的预处理技术，但在应用之前需要采取措施尽量减少氯化物的形成。
