污水厂水质变化对超滤膜的影响及其改进
发布时间：2018-08-03 06:59
【摘要】：近些年水资源短缺、城市缺水问题突出的国家,都将单纯水污染控制转变为全方位的水环境可持续发展。我国也采取了多种措施来缓解城市用水的危机,其中最主要的就是再生水回用。本研究通过污水厂不同因素对膜的影响,主要从膜通量的衰减和跨膜压差的增大,判断膜污染的主要原因;通过分析膜对胞外聚合物和溶解性微生物产物的过滤行为及对污染物的截留情况,评价膜污堵的情况,研究过滤过程中膜对胞外聚合物和溶解性微生物产物的截留和沉积情况,为优化膜的清洗策略提供技术指导;通过对比不同的运行方式,观察膜通量的衰减和跨膜压差的变化,从而改善运行方式,为超滤膜系统稳定正常的运行提供依据,同时为优化超滤系统的设计和操作参数提供有效的方法;在冬季污水厂的生化系统变化,水中出现的絮状物质,这种物质有极强的附着能力和聚集能力,在冬季需将自清洗过滤器进行调整,不能让其到了设定的自清洗压力再进行清洗,将自清洗过滤器调整为固定时间进行自清洗,根据多次的试验,最后将时间调整为15分钟。调整之后,自清洗过滤器在之后的冬季运行良好。但过了冬季仍需将自清洗过滤器调整回根据压差清洗,这样能保证系统的长时间稳定运行。超滤膜随着夏季进水水温的上升,微生物的数量增加和繁殖,造成了膜的污堵,进而造成了秋季超滤膜污堵情加剧。在进水端上加装一台计量泵,由计量泵向进水管路中输送进1Oppm的次氯酸钠,进而抑制细菌的繁殖,减少其对膜孔附着的几率,降低超滤膜系统的污堵。在超滤膜运行过程中,必须对超滤系统的反洗水进行跟踪化验,从而更进一步的了解水质的变化、主要污染物的形式、反洗是否彻底等关键因素。当发现水质发生变化,从而造成反洗去污染物的去除降低,应当适时的增加反洗时间。污水处理厂的超滤中水回用系统,其在夏季超滤膜已经开始污堵,只是由于进水水温的原因,造成超滤系统的产水水量上升,进水压力未有明显的上升,但到了秋冬季后,进水水温的降低,造成进水压力急剧上升,同时产水水量下降,若仍保持系统的到了清洗压力再进行化学清洗,会导致超滤膜无法将污染物洗出,同时由于污染积聚较多,需要使用大量NaOH和次氯酸钠对超滤膜进行清洗,而且清洗效果也不能达到最佳,超滤膜无法恢复到最初。造成化学清洗的频率越高,使超滤膜表面发生膜孔扩张和断裂现象。会造成超滤膜的不可逆的伤害,减少超滤膜的使用年限。
[Abstract]:In recent years, the shortage of water resources and the outstanding problems of urban water shortage have transformed the pure water pollution control into all-around sustainable development of water environment. China has also adopted a variety of measures to alleviate the crisis of urban water use, the most important of which is the reuse of recycled water. According to the influence of different factors on the membrane in the wastewater treatment plant, the main reasons of membrane fouling can be judged from the attenuation of membrane flux and the increase of transmembrane pressure difference. By analyzing the filtration behavior of membrane on extracellular polymer and soluble microbial products and the retention of pollutants, the situation of membrane fouling was evaluated, and the retention and deposition of membrane to extracellular polymer and soluble microbial product during filtration were studied. It can provide technical guidance for optimizing the cleaning strategy of membrane, observe the attenuation of membrane flux and the change of transmembrane pressure difference by comparing different operation modes, so as to improve the operation mode and provide the basis for the stable and normal operation of UF membrane system. At the same time, it provides an effective method for optimizing the design and operation parameters of the ultrafiltration system. It is necessary to adjust the self-cleaning filter in winter so that it cannot be cleaned to the set self-cleaning pressure. The self-cleaning filter is adjusted to a fixed time for self-cleaning. According to many experiments, the time is adjusted to 15 minutes. After adjustment, the self-cleaning filter works well in the following winter. But after winter, the self-cleaning filter should be adjusted back to clean according to the pressure difference, which can ensure the system to run steadily for a long time. With the increase of water temperature in summer, the number and propagation of microorganism increased, which resulted in fouling and blocking of membrane, which resulted in the fouling of ultrafiltration membrane in autumn. A metering pump was installed on the inlet end, from which the sodium hypochlorite (1Oppm) was transported to the inlet line, thus inhibiting the propagation of bacteria, reducing the probability of adhesion to the membrane pore, and reducing the fouling and plugging of the ultrafiltration membrane system. In the process of ultrafiltration membrane operation, it is necessary to trace and test the backwash water of the ultrafiltration system, so as to further understand the key factors, such as the change of water quality, the form of main pollutants, and whether the backwash is thorough or not. When it is found that the water quality changes, resulting in the reduction of backwash pollutants, it is necessary to increase the backwash time. The UF water reuse system of the sewage treatment plant has started fouling in the summer. It is only because of the water temperature of the influent that the water yield of the UF system increases, but the influent pressure does not increase significantly, but after autumn and winter, With the decrease of inlet water temperature, the influent pressure rises sharply, and the water yield decreases. If the system is kept at the cleaning pressure and then chemically cleaned, the ultrafiltration membrane will not be able to wash out the pollutants, and because of the accumulation of pollution, there will be a lot of pollution. A large amount of NaOH and sodium hypochlorite were used to clean the ultrafiltration membrane, and the cleaning effect was not optimal, and the ultrafiltration membrane could not be restored to the original. The higher the frequency of chemical cleaning, the larger the expansion and fracture of the membrane surface. UF membrane will cause irreversible damage, reduce the UF membrane service life.
【学位授予单位】：苏州科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703
，
本文编号：2160932
[Abstract]:In recent years, the shortage of water resources and the outstanding problems of urban water shortage have transformed the pure water pollution control into all-around sustainable development of water environment. China has also adopted a variety of measures to alleviate the crisis of urban water use, the most important of which is the reuse of recycled water. According to the influence of different factors on the membrane in the wastewater treatment plant, the main reasons of membrane fouling can be judged from the attenuation of membrane flux and the increase of transmembrane pressure difference. By analyzing the filtration behavior of membrane on extracellular polymer and soluble microbial products and the retention of pollutants, the situation of membrane fouling was evaluated, and the retention and deposition of membrane to extracellular polymer and soluble microbial product during filtration were studied. It can provide technical guidance for optimizing the cleaning strategy of membrane, observe the attenuation of membrane flux and the change of transmembrane pressure difference by comparing different operation modes, so as to improve the operation mode and provide the basis for the stable and normal operation of UF membrane system. At the same time, it provides an effective method for optimizing the design and operation parameters of the ultrafiltration system. It is necessary to adjust the self-cleaning filter in winter so that it cannot be cleaned to the set self-cleaning pressure. The self-cleaning filter is adjusted to a fixed time for self-cleaning. According to many experiments, the time is adjusted to 15 minutes. After adjustment, the self-cleaning filter works well in the following winter. But after winter, the self-cleaning filter should be adjusted back to clean according to the pressure difference, which can ensure the system to run steadily for a long time. With the increase of water temperature in summer, the number and propagation of microorganism increased, which resulted in fouling and blocking of membrane, which resulted in the fouling of ultrafiltration membrane in autumn. A metering pump was installed on the inlet end, from which the sodium hypochlorite (1Oppm) was transported to the inlet line, thus inhibiting the propagation of bacteria, reducing the probability of adhesion to the membrane pore, and reducing the fouling and plugging of the ultrafiltration membrane system. In the process of ultrafiltration membrane operation, it is necessary to trace and test the backwash water of the ultrafiltration system, so as to further understand the key factors, such as the change of water quality, the form of main pollutants, and whether the backwash is thorough or not. When it is found that the water quality changes, resulting in the reduction of backwash pollutants, it is necessary to increase the backwash time. The UF water reuse system of the sewage treatment plant has started fouling in the summer. It is only because of the water temperature of the influent that the water yield of the UF system increases, but the influent pressure does not increase significantly, but after autumn and winter, With the decrease of inlet water temperature, the influent pressure rises sharply, and the water yield decreases. If the system is kept at the cleaning pressure and then chemically cleaned, the ultrafiltration membrane will not be able to wash out the pollutants, and because of the accumulation of pollution, there will be a lot of pollution. A large amount of NaOH and sodium hypochlorite were used to clean the ultrafiltration membrane, and the cleaning effect was not optimal, and the ultrafiltration membrane could not be restored to the original. The higher the frequency of chemical cleaning, the larger the expansion and fracture of the membrane surface. UF membrane will cause irreversible damage, reduce the UF membrane service life.
【学位授予单位】：苏州科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703
，
本文编号：2160932
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