The discharge of reject brine from seawater desalination processes is a threat to marine ecosystems. This study investigated the feasibility of forward osmosis (FO) for the treatment of reject brine from multi‐effect distillation (MED) systems. The performances of two commercial FO membranes (ie, cellulose triacetate (CTA) and polyamide thin film composite (TFC) membranes) were compared. The effects of operating conditions, such as draw solution concentration, cross‐flow velocity, and temperature, on concentration polarization and consequently on the water flux, were quantitatively analyzed using a mathematical model. Results showed that the batch FO process could effectively reduce the volume of MED brine to 54.9% using 3 mol/L NaCl. As the draw solution concentration increased from 1‐5 mol/L, a significant increase in the initial water flux from 3.23‐17.88 L · m⁻² · h⁻¹ and from 3.55‐24.04 L · m⁻² · h⁻¹ was observed for the CTA and TFC membranes, respectively. However, the proportions of the effective osmotic pressure differences decreased from 20.7% to 11.9% and from 23.5% to 6.2% for the CTA and TFC membranes, respectively, indicating the concentration polarization (CP) was severe for high‐salinity brine treatment. The positive effects of increasing cross‐flow velocity on CP were limited. Moreover, the high temperature of the MED brine effectively mitigated the internal concentration polarization (ICP), thereby enhancing the water flux. Overall, this study provides valuable guidance for the application and optimization of FO in MED brine treatment.

中文翻译：

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用于多效蒸馏盐水处理的正向渗透：性能和浓度极化评估

海水淡化过程中排出的废盐水对海洋生态系统构成威胁。这项研究调查了正渗透（FO）处理多效蒸馏（MED）系统的废盐水的可行性。比较了两种商用FO膜（即三乙酸纤维素（CTA）和聚酰胺薄膜复合材料（TFC）膜）的性能。使用数学模型定量分析了操作条件（例如汲取溶液浓度，错流速度和温度）对浓度极化以及因此对水通量的影响。结果表明，使用3 mol / L NaCl，分批FO工艺可以有效地将MED盐水的体积减少至54.9％。随着汲取溶液浓度从1-5 mol / L增加，对于CTA和TFC膜，分别观察到⁻² ·h ^-1和3.55-24.04 L·m ⁻² ·h ^-1。但是，CTA和TFC膜的有效渗透压差比例分别从20.7％降低到11.9％，从23.5％降低到6.2％，这表明高盐度盐水处理中的浓度极化（CP）严重。错流速度增加对CP的积极作用是有限的。此外，MED盐水的高温有效地减轻了内部浓度极化（ICP），从而提高了水通量。总的来说，这项研究为FO在MED盐水处理中的应用和优化提供了有价值的指导。