Local water supply shortages are one of the biggest global challenges of today's generation. The only way to extend existing drinking water resources beyond what is available from the water cycle is through water reuse or desalination of sea and brackish water. At present, the most energy-efficient technology to desalinate saline waters is high pressure membrane filtration using solution-diffusion-membranes (RO: reverse osmosis). However, membrane scaling poses a major challenge on the performance of a reverse osmosis process. Membrane scaling is the deposition, accumulation and growth of crystals on the membrane surface and may occur as a consequence of surpassing solubility limits of different salts (e.g. gypsum/CaSO4∙2H2O) during filtration. Scaling layers block the membrane surface and may create an additional hydraulic resistance thus leading to loss in filtration performance and possible process failure. Numerous publications demonstrate that the presence of impurities, such as natural organic matter (NOM), can interfere with the crystallization process in aqueous solutions. In the case of membrane desalination processes, it has been shown that interactions between NOM and scaling mechanisms may alter the overall performance. An improved knowledge of these interactions supports the development of tailored measures to prevent or minimize membrane scaling.
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