Abstract:

Silica scale pollution is a common type of contamination and becomes a bottleneck issue of the stable and efficient operation in reverse osmosis (RO) systems for coal chemical wastewater treatment. But most research on silica scale pollution stays at the stage of formation mechanism and influencing factors at present, and there is a lack of case study research on the profiling and contaminant types characterization of RO membrane elements in actual coal chemical projects. This paper profiled the RO membrane elements from three typical coal chemical companies and analyzed the silica scale pollution by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). As shown in the results, there were a large number of silica scale foulants in three kinds of RO membrane elements, but the morphology and composition of silica scale were obviously different. The silica scale foulants in A membrane element were mainly silicate, while those in C membrane element were mainly colloidal silicon, and both forms existed in B membrane element silica scale foulants. Combined with conventional chemical cleaning to analyze the separation performance, appearance and elemental distribution before and after cleaning, it was further confirmed the differences in the morphological characteristics of silica scale. This study can provide a reference for the operation and cleaning of RO system for coal chemical industry.

Key words: membranes, silica, pollution, reverse osmosis, membrane cleaning

摘要：

硅垢污染是煤化工废水反渗透系统中普遍存在的污染类型，并成为反渗透系统稳定高效运行的瓶颈问题。但目前对于硅垢污染的研究大部分停留在形成机理与影响因素阶段，缺乏对实际煤化工现场反渗透膜元件的剖检实践与污染物特征类型的案例分析研究。本文通过选取3个典型煤化工企业的反渗透膜元件进行剖检，采用扫描电镜（SEM）、能量色散射线光谱（EDS）和X射线光电子能谱（XPS）等表征对膜表面的污染类型进行特征分析。结果表明3种反渗透膜表面均存在大量的硅垢污染物，但硅垢形态及组成存在明显不同，其中A膜元件硅垢污染物形态主要为硅酸盐，C膜元件硅垢污染物形态主要为胶体硅，B膜元件两种形态的硅垢污染物均存在。并结合常规化学清洗分析对比了膜片清洗前后分离性能、膜面形貌和元素的变化，进一步证实了硅垢污染物的形态特征，该研究可为煤化工反渗透系统运行与清洗提供参考。

关键词: 膜, 二氧化硅, 污染, 反渗透, 膜清洗