基于强亲水改性正渗透膜制备的炼油废水资源化关键技术研究

Large amounts of oily wastewater with complex chemical composition have been discharged from petroleum refinery industries. There is an urgent need to treat and recycle the oily wastewater effectively, which has great significance for addressing the issues of water resource shortage and environmental pollution in our country. However, the traditional biological treatment process exhibits the drawback of high energy consumption and insufficient contaminants removal. Therefore, a new technology based on forward osmosis (FO) process is proposed in this project. To improve the separation efficiency of the FO process, novel sulfonated poly(arylene ether sulfone)-poly(arylene ether sulfone) (hydrophilic block-hydrophobic block) multiblock copolymer and sulfonated poly(arylene ether sulfone) oligomer will be synthesized, and highly-permeable and fouling-resistant thin-film composite (TFC) FO membrane will be prepared by strong hydrophilic modification of the polysulfone support layer and polyamide active layer with the use of the sulfonated multiblock copolymer and oligomer, respectively. By using the high-performance FO membrane for treatment of the oily wastewater, water resource can be extracted and recycled from the wastewater efficiently; meanwhile, the organic contaminants would be concentrated correspondingly, which can be then employed for biomass energy recovery effectively. For sustainable water recovery and organic contaminants concentration, the fouling mechanisms of the TFC FO membrane by the oily wastewater during long-term operation will be investigated, the dynamic variation of fouling layer on membrane surface will be revealed, and the corresponding fouling control strategy will be established. Furthermore, the biomass energy recovery efficiency of the FO concentrated solution by anaerobic methanogenesis process will be elucidated, and the effect of salinity accumulation on the anaerobic microbial community will be clarified. For the refractory organic contaminants in the wastewater, effective co-metabolic regulation and control method will be proposed. The results of this project can provide theoretical basis and technological support for preparation of high-performance FO membrane and its application in advanced treatment and recycle of petroleum refinery wastewater.

石化炼油废水产生量大、成分复杂，将其资源化回用对于解决我国水资源短缺和环境污染问题具有重要意义。针对传统生化处理存在的出水水质差、能耗高的问题，本项目将基于新型磺化聚苯醚砜-聚苯醚砜（亲水段-疏水段）多嵌段共聚高分子和磺化聚苯醚砜齐聚物的合成，通过对聚砜支撑层和聚酰胺活性层分别进行强亲水改性，以制备高通量、抗污染的TFC正渗透膜，并以此为核心构建基于正渗透过程的炼油废水处理新技术，不仅可实现水资源的高效回收，也可对有机质高效浓缩、进而实现生物质能源的回收。同时，本项目将解析长期运行下炼油废水对TFC正渗透膜的膜污染机理，建立高效的膜污染控制策略，以满足持续稳定运行的要求；考察正渗透过程中盐度的累积对浓缩液后续通过厌氧产甲烷工艺进行生物质能源回收的影响，针对炼油废水中难降解有机物提出高效的共代谢调控方案。研究成果可为高性能正渗透膜制备及其在炼油废水资源化领域的有效应用提供理论依据和技术支持。

石化炼油行业具有水资源消耗量大、废水成份复杂的特点，亟需提高炼油废水循环利用比例，以减少水资源的消耗以及对环境的污染。传统压力驱动膜技术难以有效用于炼油废水的净化，其原因是油类污染物在水力压差下将造成严重的膜污染，使膜分离过程难以持续进行。但正渗透（FO）技术采用渗透压差代替了水力压差作为膜分离过程的驱动力，具有独特的低膜污染和高回收率等优势，在炼油废水处理领域具有显著应用潜力。但目前FO技术面临着缺乏高性能膜材料的瓶颈问题。本项目成功合成了磺化聚苯醚砜-聚苯醚砜（亲水-疏水）多嵌段共聚高分子，通过共混方法对聚砜支撑层进行强亲水改性，改善了薄膜复合正渗透膜（TFC FO膜）的渗透能力，含量为25.0 wt%时在FO模式和PRO模式下的水通量分别达到40.5 LMH和74.4 LMH，为目前文献报道中同类膜产品的最大值；同时，支撑层的机械强度得以有效保留（仅降低23%）。通过磺化聚苯醚砜齐聚物对聚酰胺活性层进行超亲水改性，提高了TFC FO膜抗油污染性能，当40 g/L Tween 80-乳化油废水回收率达80%时，改性TFC膜的水通量仍能保持初始通量的69.8%（未改性膜仅为11.0%）。为避免处理相反电性乳化油时因静电作用导致的膜污染，通过两性离子聚合物对聚酰胺活性层进行超亲水改性，制备出具有电中性和盐响应性TFC FO膜，在处理三种不同荷电性乳化油时，均展现出更好的抗乳化油污染特性；但长期运行下膜表面有不可逆污染的产生，可以利用PSBMA对盐溶液的响应特性，通过盐溶液清洗使两性离子改性膜的水通量得到很好的恢复。在此基础上，评价了不同清洗方法对污染后两性离子聚合物改性膜的清洗效率，结果表明正渗透膜的表面抗污染特性和有效清洗方案的组合可以保持FO工艺出水通量的稳定性。研究成果为炼油废水等高污染势废水深度处理与资源化回用提供了理论依据和技术支持。