Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, PR China.
Jiangsu Key Laboratory of Anaerobic Biotechnology, School of Environmental and Civil Engineering, Jiangnan University, Wuxi 214122, PR China.
Water Res. 2015 May 15;75:188-200. doi: 10.1016/j.watres.2015.02.048. Epub 2015 Mar 5.
Since the concept of the osmotic membrane bioreactor (OMBR) was introduced in 2008, it has attracted growing interests for its potential applications in wastewater treatment and reclamation; however, the fouling mechanisms of forward osmosis (FO) membrane especially the development of biofouling layer in the OMBR are not yet clear. Here, the fouled FO membranes were obtained from the OMBRs on days 3, 8 and 25 in sequence, and then the structure and growing rule of the biofouling layer formed on the FO membrane samples were in-situ characterized by multiple fluorescence labeling and confocal laser scanning microscopy (CLSM). CLSM images indicated that the variations in abundance and distribution of polysaccharides, proteins and microorganisms in the biofouling layer during the operation of OMBRs were significantly different. Before the 8th day, their biovolume dramatically increased. Subsequently, the biovolumes of β-d-glucopyranose polysaccharides and proteins continued increasing and leveled off after 8 days, respectively, while the biovolumes of α-d-glucopyranose polysaccharides and microorganisms decreased. Extracellular polymeric substances (EPS) played a significant role in the formation and growth of biofouling layer, while the microorganisms were seldom detected on the upper fouling layer after 3 days. Based on the results obtained in this study, the growth of biofouling layer on the FO membrane surface in the OMBR could be divided into three stages. Initially, EPS was firstly deposited on the FO membrane surface, and then microorganisms associated with EPS located in the initial depositing layer to form clusters. After that, the dramatic increase of the clusters of EPS and microorganisms resulted in the quick growth of biofouling layer during the flux decline of the OMBR. However, when the water flux became stable in the OMBR, some microorganisms and EPS would be detached from the FO membrane surface.
自 2008 年渗透膜生物反应器（OMBR）的概念被引入以来，由于其在废水处理和再利用方面的潜在应用，它引起了越来越多的关注；然而，正向渗透（FO）膜的污染机制，特别是在 OMBR 中生物污垢层的发展，尚不清楚。在这里，从 OMBR 中连续在第 3、8 和 25 天获得了污染的 FO 膜，然后通过多重荧光标记和共聚焦激光扫描显微镜（CLSM）原位表征了在 FO 膜样品上形成的生物污垢层的结构和生长规律。CLSM 图像表明，在 OMBR 运行过程中，生物污垢层中多糖、蛋白质和微生物的丰度和分布变化显著不同。在第 8 天之前，它们的生物量急剧增加。随后，β-d-吡喃葡萄糖多糖和蛋白质的生物量分别在第 8 天后继续增加并趋于稳定，而α-d-吡喃葡萄糖多糖和微生物的生物量则减少。细胞外聚合物（EPS）在生物污垢层的形成和生长中起重要作用，而在第 3 天后，很少在较上层污垢层中检测到微生物。根据本研究的结果，在 OMBR 中 FO 膜表面生物污垢层的生长可以分为三个阶段。最初，EPS 首先沉积在 FO 膜表面，然后与 EPS 相关的微生物位于初始沉积层中形成聚集体。之后，EPS 和微生物聚集体的急剧增加导致 OMBR 通量下降期间生物污垢层的快速生长。然而，当 OMBR 中的水通量稳定时，一些微生物和 EPS 会从 FO 膜表面脱落。
