King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Thuwal, Saudi Arabia; Delft University of Technology, Faculty of Applied Sciences, Department of Biotechnology Delft, The Netherlands.
King Abdullah University of Science and Technology, Water Desalination and Reuse Center, Thuwal, Saudi Arabia.
Water Res. 2014 Jun 15;57:223-33. doi: 10.1016/j.watres.2014.03.046. Epub 2014 Mar 27.
Forward osmosis (FO) indirect desalination systems integrate wastewater recovery with seawater desalination. Niche applications for FO systems have been reported recently, due to the demonstrated advantages compared to conventional high-pressure membrane processes such as nanofiltration (NF) and reverse osmosis (RO). Among them, wastewater recovery has been identified to be particularly suitable for practical applications. However, biofouling in FO membranes has rarely been studied in applications involving wastewater effluents. Feed spacers separating the membrane sheets in cross-flow systems play an important role in biofilm formation. The objective of this study was to determine the influence of feed spacer thickness (28, 31 and 46 mil) on biofouling development and membrane performance in a FO system, using identical cross-flow cells in parallel studies. Flux development, biomass accumulation, fouling localization and composition were determined and analyzed. For all spacer thicknesses, operated at the same feed flow and the same run time, the same amount of biomass was found, while the flux reduction decreased with thicker spacers. These observations are in good agreement with biofouling studies for RO systems, considering the key differences between FO and RO. Our findings contradict previous cross-flow studies on particulate/colloidal fouling, where higher cross-flow velocities improved system performance. Thicker spacers reduced the impact of biofouling on FO membrane flux.
正向渗透（FO）间接脱盐系统将废水回收与海水脱盐相结合。由于与纳滤（NF）和反渗透（RO）等传统高压膜工艺相比具有明显优势，FO 系统最近有了一些特定的应用。其中，废水回收已被确定为特别适合实际应用的领域。然而，在涉及废水的应用中，FO 膜中的生物污染问题很少得到研究。在错流系统中，用于分离膜片的进料隔片在生物膜形成中起着重要作用。本研究的目的是确定在使用相同的错流池进行平行研究的情况下，FO 系统中进料隔片厚度（28、31 和 46 密耳）对生物污染发展和膜性能的影响。测定并分析了通量发展、生物量积累、污染定位和组成。对于所有的隔片厚度，在相同的进料流量和相同的运行时间下，都发现了相同数量的生物量，而通量减少则随着隔片厚度的增加而减少。这些观察结果与 FO 和 RO 之间的关键差异相一致，与 RO 系统的生物污染研究结果一致。我们的发现与之前关于颗粒/胶体污染的错流研究结果相矛盾，在错流研究中，较高的错流速度可以提高系统性能。较厚的隔片减少了生物污染对 FO 膜通量的影响。
