Tianjin Key Laboratory of Environmental Technology for Complex Trans-Media Pollution, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China.
Tianjin Key Laboratory of Environmental Technology for Complex Trans-Media Pollution, College of Environmental Science and Engineering, Nankai University, Tianjin, 300350, China.
Water Res. 2020 Jul 15;179:115847. doi: 10.1016/j.watres.2020.115847. Epub 2020 Apr 27.
Electrodialysis (ED) is a well-established brackish water (BW) desalination technology that has been commercially applied for decades. However, the energy efficiency of BWED cannot approach optimization because of the low salt concentration of BW. In this study, a novel two hydraulic-stage ED desalination system was presented to enhance mass transfer and reduce energy consumption. In terms of energy-efficient strategies, it involved not only innovative membrane stack configurations (resin-filled electrode cells and asymmetric cell pairs design) but also optimizing inflow modes (electrolytes parallel flow and dilute/concentrate counter flow). Results showed that thin resin-filled (1 mm) electrode cells, asymmetric cell pair design (cell pairs ratio of 1st and 2nd-hydraulic stages, 1.2), and optimizations of general inflow mode were beneficial for savings 10-30% of energy consumption at the same salt removal ratio (SR). The synergistic effects of these strategies indicated that this novel ED system could save ∼40% of the energy consumption at the same SR, compared with conventional two hydraulic-stage ED system (CED). Three stage continuous BWED performance tests, compared with a CED, showed that a 36.9% total energy saving could be achieved using the novel ED system when the BW concentration decreased from 3500 mg/L to the quality requirement of drinking water (∼450 mg/L). It was therefore possible to open the way for saving energy in BWED systems.
电渗析（ED）是一种成熟的苦咸水（BW）淡化技术，已经商业化应用了几十年。然而，由于 BW 的盐度低，BWED 的能源效率无法接近优化。在这项研究中，提出了一种新颖的两级水力 ED 脱盐系统，以增强传质并降低能耗。在节能策略方面，它不仅涉及创新的膜堆配置（填充树脂的电极单元和非对称电池对设计），还涉及优化入口模式（电解质平行流和稀释/浓缩逆流）。结果表明，薄填充树脂（1mm）电极单元、非对称电池对设计（第一级和第二级水力阶段的电池对比例为 1.2）以及优化通用入口模式有利于在相同的脱盐率（SR）下节省 10-30%的能耗。这些策略的协同效应表明，与传统的两级水力 ED 系统（CED）相比，这种新型 ED 系统在相同的 SR 下可节省约 40%的能耗。与 CED 相比，三级连续 BWED 性能测试表明，当 BW 浓度从 3500mg/L 降低到饮用水质量要求（约 450mg/L）时，新型 ED 系统可实现 36.9%的总节能。因此，有可能为 BWED 系统节省能源开辟道路。
