近日，大湾区城市环境安全与绿色发展教育部重点实验室学术骨干王樟新教授在环境领域著名期刊Water Research上发表了题为“Module-Scale undefinedysis of Low-Salt-Rejection Reverse Osmosis: Design Guidelines and System Performance”的研究论文。该研究通过对低脱盐率反渗透技术（LSRRO）进行组件尺度的分析，阐明了LSRRO系统的设计准则，并进一步评估了其系统性能。该研究成果可推进LSRRO技术的落地。

    论文DOI：https://doi.org/10.1016/j.watres.2021.117936

当前的工业会产生大量的高盐废水，而传统的高盐废水处置途径存在着环境危害和高成本等问题。为了减少高盐废水排放对环境的负面影响，政府推出了愈加严格的排放法规，废水零或近零排放（ZLD）应运而生。ZLD旨在同时消除废水排放并回收淡水资源，因而可以最大限度地减少环境风险并提高淡水利用效率。

ZLD系统中，废水首先通过膜法和热法浓缩，最后经结晶完全脱除水分。但是热法浓缩的高投资和运行成本限制了ZLD的大规模应用。为了降低ZLD降本，需要尽可能地使用膜法技术（通常为反渗透RO技术）高倍率浓缩废水，减少热法浓缩的运行负荷。在常规的RO中，为了避免压力对膜和组件的不利影响，操作压力受限，而这也限制了废水的浓缩倍率。

为了克服传统RO技术中操作压力对废水浓缩倍率的限制，我们在之前的研究中设计了一种使用低脱盐率组件的多级RO装置，称之为低脱盐率反渗透（LSRRO）。如图1所示，一个N级LSRRO系统包括一个常规RO组件和N-1个LSRRO组件。在运行过程中，每一级的浓水被送到下一级作为进水，而其产水则被加压循环回上一级重新浓缩。在使用相同的操作压力时，LSRRO可以比传统的RO更有效地浓缩盐水并减少体积。

本研究中，我们对LSRRO系统进行了组件尺度的数值模拟，以更精确地评估系统性能并为未来的系统放大提供指导。我们首先说明了LSRRO组件盐脱盐率的调控方法，并通过阐明膜特性和操作条件对两级LSRRO系统性能的影响来进一步描述LSRRO系统的设计准则。最后，我们系统地评估了LSSRO系统在ZLD场景中的应用并讨论了该技术的潜力和未来开发的需求。

英文摘要：

Low-salt-rejection reverse osmosis (LSRRO) is a novel reverse osmosis (RO)-based technology that can highly concentrate brines using moderate operating pressures. In this study, we investigate the performance of LSRRO membrane modules and systems using module-scale analysis. Specifically, we correlate the observed salt rejection of an LSRRO module with the water and salt permeabilities of the RO membrane. We then elaborate the impact of membrane properties and operating conditions on the performance of a 2-stage LSRRO, providing design guidelines for LSRRO systems. We further compare the performance of 2-stage and 3-stage LSRRO systems, showing that an LSRRO system with more stages is not always favored due to a larger energy consumption. The performance of a 3-stage LSRRO in treating different feed solutions for minimal/zero liquid discharge (MLD/ZLD) applications is then evaluated. Based on our results, when treating feed waters with a relatively low salinity (e.g., 0.1 M or ∼5,800 mg L−1 NaCl), the 3-stage LSRRO can achieve a concentrated brine that can be directly sent to the thermal brine crystallizers (i.e., brine concentration > 4 M or ∼240,000 mg L−1 NaCl), and the corresponding specific energy consumption (SEC) is only ∼3 kWh m−3. When treating feed waters with a relatively high salinity (e.g., 0.6 M or ∼35,000 mg L−1 NaCl), the brine from the 3-stage LSRRO can be ∼80 % more concentrated compared to that from conventional RO, while the corresponding SEC does not exceed 6 kWh m−3. Our results demonstrate that LSRRO can substantially advance minimal/zero liquid discharge (MLD/ZLD) applications because it can significantly minimize the use of thermal brine concentrators. We conclude with a discussion on the practicability of LSRRO and highlight future research needs.