【作者】 衣雪松；

【导师】 于水利； 时文歆；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2012， 博士

【摘要】 本课题从研究油田三次采出水水质特点出发，以解构和建构理论为指导，通过研究考察超滤过程的宏观现象，辅以微观液-固界面的相互作用深入剖析，阐明了油田三次采出水对超滤膜污染的影响因子及污染机制，建立了油田采出水的超滤膜污染模型，优化了运行工艺条件，并提出了相应的污染控制措施。为TiO₂/Al₂O₃-PVDF超滤膜在油田采出水的实际应用提供重要的理论基础和技术支持。首先，对比研究了不同操作压力、料液浓度、温度、pH值、矿化度等条件下，PVDF膜及纳米改性TiO₂/Al₂O₃-PVDF膜处理油田采出水时主要有机物的截留率及透水量。结果表明，渗透液中乳化液（O/W）的浓度在0.5mg/L以下，可达油田低渗透层回注要求。进而，通过响应曲面法优化分析了超滤去除水中主要污染物过程中的最佳操作条件，结果显示，操作压力对超滤过程的通量衰减起最主要作用；在此基础上确定的改性膜超滤过程的通量预测模型，可为其在采出水处理中的实际应用提供理论参考。其次，通过研究采出水中两种典型的高分子污染物在超滤膜上的吸附性能，发现亲水性有机物阴离子型聚丙烯酰胺（APAM）给改性膜造成的污染相对严重，疏水性的O/W相对较轻。通过考察两种膜对APAM及O/W的静态吸附，发现两种膜对二者的吸附等温线分别为Langmuir-Freundlich型和Redlich-Peterson型；且APAM在两种膜上的吸附能力均随pH的升高而降低，随温度的升高而升高；阳离子对两种膜吸附APAM的影响较大,吸附作用的相对大小为Na⁺＜K⁺＜Ca²⁺,阴离子作用不显著。在pH值2.0¹2.0的范围内，O/W在两种膜上的吸附量随pH值的升高先升高后降低；随温度的升高而降低；阴、阳离子的加入均促进了O/W吸附量的增加。说明改性膜抗污能力的提升是具有针对性的。再次，通过对比分析不同运行模式下超滤通量衰减过程，建立了不同膜阻力对超滤通量衰减贡献的数学模型。得出：膜孔堵塞过程发生迅速且持续时间短，主要发生在超滤开始的前4min，但该过程造成的通量衰减却十分显著；凝胶层形成包括三个阶段，即浓差极化阶段、凝胶层形成阶段及凝胶层稳定阶段，此过程需经过30min完成，所得凝胶形成模型可以较好的对该过程进行模拟；以污染物-膜的静态吸附为基础，建立的吸附污染阻力引起的通量衰减数学模型可以很好的解释超滤过程中慢污染情况，该部分阻力引起的通量衰减在超滤后期起主导作用，且该过程持续时间较长。经典的“Cake”模型对整个超滤过程进行模拟，随超滤时间的延长适应性变差；故此，建立了基于各因素之间内在关系的白金汉模型，该模型能够简单、有效的模拟不同废水的超滤过程。第四，以前期实验为基础，以管式膜组件的形式，将改性PVDF膜和PVDF原膜应用于油田采出水的处理过程中，考察了操作压力对两种超滤膜透水性能的影响及出水水质随时间的变化趋势。结果表明：高压操作仅对增大膜的初始通量具有较明显的作用，低压操作则能更好地降低膜污染，维持膜通量的相对稳定。对比两种膜处理采出水出水发现，运行稳定后，两种膜的出水水质差别不大，渗透液浊度均低于0.5NTU；含油量均小于0.6mg/L；含聚量均小于0.2mg/L；TOC值小于170mg/L。最后，研究了油田采出水超滤过程的临界通量。结果表明，压力较低、pH中性、温度303K时，系统存在一个较低的临界通量，长期运行时，临界通量与非临界通量下的产水量相当，但膜污染缓慢、能耗大大降低。针对油田采出水中的不同污染物，研究了不同的物理-化学组合清洗方法，其中，水力冲洗、反冲、机械刮除的效果不佳，而化学方法中的NaClO（1%）的清洗效果较好，其次是HCl（1%）和十二烷基硫酸钠（SDS，0.5%），不建议采用超声波清洗。同样的清洗条件，改性膜的通量恢复明显高于原膜。更多还原

【Abstract】 This subject started from the characteristics of oil field produced water, based onthe theory of deconstruction and construction, through examination of themacro-phenomenon of the ultrafiltration process, supplemented by micro-liquid-solid interface interaction in-depth analysis to clarify the impact factors andmembrane fouling mechanism of this UF process. Moreover, membrane foulingmathematic models and corresponding pollution control measures were also carriedout. Thus, this study can provide an important theoretical basis and a technicalsupport for the practical application of TiO₂/Al₂O₃-PVDF ultrafiltration membranein the oilfield produced water.Firstly, the comparative study of operating pressure, feed concentration,temperature, pH, salinity and other conditions on the rejection rate of the mainorganic matter and permeate flux have been carried out. The results show that theO/W concentrations in permeate liquid was lower than0.5mg/L, which achieved thestandard of rejection in the low permeability layer of earth. Furthermore, theultrafiltration process operating conditions were optimized by the response surfacemethodology （RSM）, indicating that the operating pressure played a determined roleon the relative flux decline. Since then, the relative filtration flux prediction modelsfor different types of the modified membrane was investigated, which can provide atheoretical reference for the practical application of oil field produced water.Secondly, the adsorption performance of two kinds of membranes with two typesof different pollutants （APAM and O/W） was discussed. It was found that theTiO₂/Al₂O₃-PVDF membrane was polluted by the hydrophilic organic APAM wasmore serious than PVDF membrane, while the contrary results was got by O/W. Theadsorption isotherms of APAM-membrane and O/W-membrane adsorption systemwere Langmuir-Freundlich type and the Redlich-Peterson type, respectively.Moreover, the adsorption capacity of APAM by the two membranes was inverselyproportional to the pH value, while proportional to temperature. Cations have anobvious effect on this adsorption of APAM, and the relative capacity was: Na⁺<K⁺<Ca²⁺, but anion did not play a significant role. For the adsorption of O/W, theadsorption capacity of the O/W first increased and then decreased with pH value raising （between2.0and12.0）; while, decreased with temperature increasing;anions and cations did promote the O/W adsorption capacity on the membranes. Allin all, this indicating that, for some certain pollutants, this anti-fouling abilityincreased of modified membrane can be seen.Through comparative analysis of flux attenuation caused by the pollutants in thedifferent operating mode, the mathematical models on the major membraneresistance contribute to the ultrafiltration flux attenuation have been set up. Thenthe conclusions were drawn as: the membrane pore blocking occurs rapidly, lastinga very short time of about4min, but caused a significant flux decline; Gel layerformation consists of three phases, namely concentration polarization stage, the gellayer forming stage, and the stable gel layer stage, which needs about30min, andhas a significant contribution on flux attenuation; The adsorption fouling resistancemodel based on the static adsorption of the pollutants-membranes, can be used toexplain the slow pollution phenomenon of permeate flux decline process, and, thiskind of resistance plays a determined role in the late stage with a longer duration,nearly equal to the static adsorption equilibrium time. It was found that, theadaptability of the classic “Cake” model is getting worse with ultrafiltration timeextended when simulate the entire UF process. Thus, the "Buckingham" modelbased on the intrinsic relationship between the factors were established; although itis very simple, it is effective in simulating different wastewater UF process.Thirdly, on the basis of previous experiments, the form of a tubular membranemodule was used in oilfield produced water treatment process. The effects ofoperating pressure on the performance of the two ultrafiltration membranespermeable flux and water quality trends over time were investigated, and the resultsshow that high-pressure can only effect on the initial flux, while low-pressureoperation can reduce the membrane fouling, and maintain the relative stability ofthe membrane flux. After comparing the qualities by the two membranes, it wasfound that the water qualities by the two films has no obvious difference, theturbidity in the penetration was lower than0.5NTU, TOC value lower than170mg/L,O/W and APAM concentration was lower than0.6mg/L and0.2mg/L, respectively.Finally, the critical flux of oilfield produced water by dead-end ultrafiltrationprocess was investigated. The results show that the system has a relative low criticalflux with low pressure, neutral pH, temperature30°C, etc. The permeate water production was nearly the same between the system running with critical flux andun-critical flux with a long-running, however, membrane fouling slowed down andthe energy consumption decreased in critical flux model operation. For differentpollutants, different physical-chemical combination of cleaning methods werestudied, which, the effect of hydro washing, recoil, mechanical scrape was poor;while, cleaning by NaClO （1%）, followed by HCl （1%） and SDS （0.5%） has ansignificant effect. Moreover, ultrasonic （US） cleaning was not recommended. Withcertain cleaning method, the modified membrane flux recovery was significantlyhigher than the original membrane.更多还原