In this study, a hybrid ultrafiltration–forward osmosis system was compared with a dual stage ultrafiltration process for the harvesting of marine microalgae. To the best of the author’s knowledge none of the previous studies compared the performance of a dual stage ultrafiltration process with a hybrid UF-FO process for the harvesting of marine microalgae. The application of the hybrid process is expected to reduce the energy consumption for harvesting the microalgae without affecting the concentration factor and final product quality. In forward osmosis, the impact of the feed and draw solutions flowrate and the membrane orientation was investigated. The feed solutions were unfiltered microalgae solution and ultrafiltered concentrated microalgae while the draw solution was brine collected from a thermal desalination plant. A maximum total algal harvesting concentration factor of 37.3 was obtained using the hybrid ultrafiltration-forward osmosis system and the dual stage ultrafiltration process. The flowrate used in the forward osmosis process was 2.5 LPM for the feed solution and 0.8 LPM for the draw solution and the active layer was facing the feed solution (i.e. FO mode). The energy consumption in the hybrid ultrafiltration-forward osmosis system was 24% less than the dual-stage ultrafiltration system.

在这项研究中，将混合超滤-正向渗透系统与双阶段超滤过程用于海洋微藻的收获进行了比较。据作者所知，先前的研究均未将双级超滤过程与混合UF-FO工艺用于海洋微藻收获的性能进行比较。预计混合工艺的应用将减少收获微藻的能耗，而不会影响浓缩因子和最终产品质量。在正向渗透中，研究了进料和汲取溶液流速和膜取向的影响。进料溶液是未过滤的微藻溶液和超滤的浓缩微藻，而汲取溶液是从热脱盐厂收集的盐水。使用混合超滤-正向渗透系统和双阶段超滤过程可获得最大的总藻类收获浓缩因子为37.3。正向渗透过程中使用的进料溶液流量为2.5 LPM，汲取溶液流量为0.8 LPM，且活性层面向进料溶液（即FO模式）。混合超滤-正向渗透系统的能耗比双级超滤系统低24％。