【作者】 纪海霞；

【导师】 王晓昌；

【作者基本信息】 西安建筑科技大学 ， 市政工程， 2003， 硕士

【摘要】 本研究采用截留分子量分别为100,000Da和20,000Da的国产中空纤维超滤膜对西安市北石桥污水净化中心的二沉池出水进行了深度处理实验。实验采用超滤自动控制系统实现了对操作条件的自动控制和实验数据的自动采集，提高了实验精度。实验分析了超滤对污水的处理效果及消毒效果。并比较了同种膜材质，不同截留分子量的超滤膜对污水中几种重要指标的去除效果，以及在运行过程中膜通量的变化情况。实验还通过周期反冲洗以及无反冲洗时不同压力下、不同回收率下的膜阻力变化情况分析了运行条件对膜污染的影响。 从滤后水质看出超滤膜对浊度、细菌总数及大肠杆菌的去除效果良好。原水浊度在1.82～3.56NTU范围内，出水浊度均小于0.5NTU。细菌总数和大肠杆菌的去除率均大于99％。超滤膜对污水中有机物有一定的去除，但去除率不高。不同截留分子量的膜对COD_Cr、TOC、UV_254,、色度的去除率稍有差异，20,000Da膜的去除率略高于100,000Da膜。截留分子量对超滤过程中膜通量的变化有很大影响，膜过滤初期20,000Da膜通量衰减严重。膜长期运行时，100,000Da膜通量衰减幅度较大。 直接超滤实验结果表明，反冲洗能够在一定程度上缓解膜污染。适当的回收率和进膜压力都可以有效减小膜污染。通过对膜污染数学模型的分析，明确了在过滤初期，膜孔窄化是造成渗透通量下降的主要机理；而过滤后期，滤饼层的形成是造成渗透通量下降的主要机理，因此运用阶段模型可更好的模拟膜污染过程。更多还原

【Abstract】 Hollow fiber UF membrane with 1 105 and 2 104Da were used to treat the secondary effluent from Xi’an Bei Shi Qiao Sewage Purification center. The study investigated the characteristics of UF for the removal of turbidity, organic substances and bacteria. When MWCO of UF membrane is different, the removal efficiency of UF membrane for waste is different and the permeate flux decline with operation time is also different. At the same time the study investigated the effect of backwashing, feed-water recovery and pressure on membrane resistance.In order to realize automatic control of the UF system and date acquisition and improve the accuracy of experiment result, the UF automatic system was used to meet the need of continuous experiment.The results show that UF can almost remove the turbidity completely. The permeate turbidity is lower than 0.5NTU when raw water turbidity isl.82~3.56 NTU. UF also performs physical disinfection well. It can achieve 99% removal efficiency of bacteria and E.coli. UF can remove organic substances in wastewater, but the removal efficiency is not high. Compared with UF membrane with 1 105Da, UF membrane with 2 104Da can remove organic substances in wastewater more effectively, but the difference is not obvious. In the initial period of a filtration circle, the permeate flux decline of UF membrane with 2x 104Da is larger, but the permeate flux decline is smaller afterwards.The results show that membrane fouling can be prevented more or less by backwashing. Lower feed-water recovery and higher pressure can keep higher flux. By the analysis of membrane fouling mathematic model, a conclusion can be drown that in the initial period of a filtration circle , permeate flux decline is resulted mainly by membrane pore blocking ;while in the final period, mainly by cake formation. Based on this, a two-stage mathematic model for the description mechanism of membrane fouling was proposed.更多还原