Blandin Gaetan, Ferrari Federico, Lesage Geoffroy, Le-Clech Pierre, Héran Marc, Martinez-Lladó Xavier
Eurecat, Centre Tecnològic de Catalunya, Water, Air and Soil Unit, 08242 Manresa, Spain.
Institut Européen des Membranes, IEM, Université de Montpellier, CNRS, ENSCM, 34090 Montpellier, France.
Membranes (Basel). 2020 Oct 14;10(10):284. doi: 10.3390/membranes10100284.
In the past few years, osmotic membrane systems, such as forward osmosis (FO), have gained popularity as "soft" concentration processes. FO has unique properties by combining high rejection rate and low fouling propensity and can be operated without significant pressure or temperature gradient, and therefore can be considered as a potential candidate for a broad range of concentration applications where current technologies still suffer from critical limitations. This review extensively compiles and critically assesses recent considerations of FO as a concentration process for applications, including food and beverages, organics value added compounds, water reuse and nutrients recovery, treatment of waste streams and brine management. Specific requirements for the concentration process regarding the evaluation of concentration factor, modules and design and process operation, draw selection and fouling aspects are also described. Encouraging potential is demonstrated to concentrate streams more than 20-fold with high rejection rate of most compounds and preservation of added value products. For applications dealing with highly concentrated or complex streams, FO still features lower propensity to fouling compared to other membranes technologies along with good versatility and robustness. However, further assessments on lab and pilot scales are expected to better define the achievable concentration factor, rejection and effective concentration of valuable compounds and to clearly demonstrate process limitations (such as fouling or clogging) when reaching high concentration rate. Another important consideration is the draw solution selection and its recovery that should be in line with application needs (i.e., food compatible draw for food and beverage applications, high osmotic pressure for brine management, etc.) and be economically competitive.
在过去几年中，渗透膜系统，如正向渗透（FO），作为“温和”的浓缩工艺受到了广泛关注。正向渗透具有独特的性能，它结合了高截留率和低污染倾向，并且可以在无显著压力或温度梯度的情况下运行，因此可以被视为众多浓缩应用的潜在候选技术，而目前的技术在这些应用中仍存在严重局限性。本文综述广泛收集并批判性地评估了近期将正向渗透作为一种浓缩工艺应用于食品和饮料、有机增值化合物、水回用和养分回收、废物流处理及盐水管理等领域的相关研究。文中还描述了浓缩工艺在浓缩因子评估、组件与设计、工艺操作、汲取液选择和污染方面的具体要求。研究表明，正向渗透具有令人鼓舞的潜力，能够以高截留率浓缩物流超过20倍，并保留增值产品。对于处理高浓度或复杂物流的应用，与其他膜技术相比，正向渗透仍具有较低的污染倾向，同时具备良好的通用性和稳健性。然而，预计还需要在实验室和中试规模上进行进一步评估，以更好地确定可实现的浓缩因子、截留率和有价值化合物的有效浓缩程度，并明确证明在达到高浓缩率时的工艺局限性（如污染或堵塞）。另一个重要考虑因素是汲取液的选择及其回收，这应符合应用需求（例如，食品和饮料应用中与食品兼容的汲取液，盐水管理中高渗透压的汲取液等），并且在经济上具有竞争力。
