Environmental Simulation and Pollution Control State Key Joint Laboratory, State Environmental Protection Key Laboratory of Microorganism Application and Risk Control (SMARC), School of Environment, Tsinghua University, Beijing 100084, PR China.
Beijing Yizhuang Water Co., Ltd., Beijing 100176, PR China.
Sci Total Environ. 2020 Apr 15;713:136673. doi: 10.1016/j.scitotenv.2020.136673. Epub 2020 Jan 13.
Membrane fouling is an inevitable disadvantage of the reverse osmosis (RO) process for wastewater reclamation. In order to clarify the development process of membrane fouling, all the fouled membranes along a feed channel of a two-stage industrial-scale RO system for wastewater reclamation (six elements in each stage) were autopsied and analyzed. The water flux and salt rejection efficiency of the fouled membranes at the head and tail were the lowest among 12 elements, thereby indicating more severe fouling on these membranes. In this RO system, most of the organic compounds deposited on the head elements of each stage were mainly composed of proteins, polysaccharides, and fulvic acid. The ATP concentrations of the foulants on the first and twelfth elements were much higher than those of the other elements, suggesting severe biofouling. Although microbes can cause organic fouling owing to extracellular polymeric substances production, no clear correlation was found between organic fouling and biofouling in this study. For example, the ATP concentrations on the second element and seventh element were similar (1.16 ng/cm and 1.26 ng/cm, respectively), thereby suggesting a similar extent of biofouling, but organic fouling of the second element was relatively slight (DOC: 24.8 mg/m) compared with that of the seventh element (DOC: 46.2 mg/m). The seventh element (ATP: 1.26 ng/cm) was more severely biofouled than the eighth element (ATP: 0.15 ng/cm), but they suffered from the same level of organic fouling (DOC: 46.2 mg/m and 47.1 mg/m, respectively). Approximately 70% of metallic elements, predominantly Fe, were deposited on the first element. Although the concentration of Fe in the feed water was much lower than those of Ca and Mg, the concentration of Fe on the first three elements was significantly higher than that of any other element, suggesting that Fe was more easily deposited on the RO membranes.
膜污染是反渗透（RO）工艺用于废水回收的一个不可避免的缺点。为了阐明膜污染的发展过程，对两级工业规模 RO 系统（每个阶段 6 个元件）用于废水回收的一个进料通道中的所有污染膜进行了尸检和分析。在 12 个元件中，头端和尾端污染膜的水通量和盐截留效率最低，表明这些膜的污染更严重。在该 RO 系统中，大多数有机化合物沉积在每个阶段的头端元件上，主要由蛋白质、多糖和腐殖酸组成。第一和第十二元件上污染物的 ATP 浓度明显高于其他元件，表明严重的生物污染。尽管微生物可以由于细胞外聚合物的产生而导致有机污染，但在本研究中未发现有机污染与生物污染之间存在明显的相关性。例如，第二元件和第七元件上的 ATP 浓度相似（分别为 1.16ng/cm 和 1.26ng/cm），表明生物污染程度相似，但第二元件的有机污染相对较轻（DOC：24.8mg/m），而第七元件的有机污染较严重（DOC：46.2mg/m）。第七元件（ATP：1.26ng/cm）比第八元件（ATP：0.15ng/cm）受到更严重的生物污染，但它们遭受相同程度的有机污染（DOC：46.2mg/m 和 47.1mg/m）。大约 70%的金属元素，主要是 Fe，沉积在第一元件上。尽管进水 Fe 的浓度远低于 Ca 和 Mg，但第一到三个元件上的 Fe 浓度明显高于任何其他元素，表明 Fe 更容易沉积在 RO 膜上。
