In this work, the salinity of permeate obtained with membrane distillation (MD) in pilot scale systems was analyzed. Experiments were performed with three different spiral-wound commercial modules, one from Solar Spring with 10 m2 surface membrane area and two from Aquastill with 7.2 and 24 m2. Intermittent operation meant that high permeate conductivity was measured in the beginning of each experiment, which was gradually decreasing until reaching a constant value (3–143 µS·cm−1 for seawater feed). The final quality reached did not depend on operating conditions, only the time it took to reach it. This can be because the permeate flux dilutes the minimal feed leak taking place through pinholes in the membranes. Larger feed leak through the membrane was observed when operating in vacuum-enhanced air-gap MD configuration (V-AGMD), which is compatible with this explanation. However, for the increase of feed leak with salinity (up to 1.8 M), a conclusive explanation cannot be given. Pore wetting due to crystallization is discarded because the high permeate quality was recovered after washing with distilled water. More studies at higher salinities and also at membrane level are required to investigate this.
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机译：在这项工作中，分析了在中试规模的系统中通过膜蒸馏（MD）获得的渗透物的盐度。使用三种不同的螺旋缠绕商业模块进行了实验，一种来自Solar Spring，具有10 m 2 的表面膜面积，另外两种来自Aquastill，具有7.2和24 m 2 。间歇操作意味着在每个实验的开始都测量了高渗透率电导率，该渗透率逐渐降低直到达到恒定值（海水进料为3–143 µS·cm -1 ）。达到的最终质量不取决于操作条件，仅取决于达到它所花费的时间。这可能是因为渗透通量稀释了通过膜针孔发生的最小进料泄漏。当在真空增强的气隙MD配置（V-AGMD）中运行时，观察到较大的进料通过膜泄漏，这与该说明兼容。但是，由于盐度（不超过1.8 M）的进料泄漏增加，无法给出结论性的解释。由于用蒸馏水洗涤后可回收高渗透质量，因此消除了由于结晶而产生的孔润湿。需要对此进行更多的研究，包括更高的盐度以及更高的膜水平。
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