超滤处理BAF工艺出水过程中膜污染特性及控制研究

发布时间：2018-04-27 15:29

本文选题：超滤 + BAF工艺　；参考：《清华大学》2015年硕士论文

【摘要】：膜技术在城市给水和污水处理领域有着很多优点,研究膜处理过程中膜污染形成的原因以及膜污染控制方法,对延缓膜使用寿命,降低运行成本有着重要意义。本论文以北京市碧水源科技有限公司平谷区再生水厂及再生水利用工程为依托,研究超滤处理曝气生物滤池工艺出水过程中膜污染的机理及其膜污染控制。主要结论如下。超滤膜对BAF工艺出水中DOC、UV_(254)和COD_(Cr)浓度的去除率不高,仅仅在5%左右;对浊度的去除效果非常良好,出水浊度均维持在0.2NTU以下;对颗粒物的去除效果非常良好,去除率高达95%以上。在恒压过滤和恒通量过滤两种模式下,均发现了膜污染现象。通过SEM扫描电镜观察发现,随着过滤的进行,BAF工艺出水中的污染物沉积在超滤膜表面,形成了厚实的滤饼层。BAF工艺出水中不同亲疏水性组分对于超滤膜造成的污染程度各不相同,四种组分对超滤膜污染的贡献大小依次为亲水性有机物疏水碱性有机物疏水酸性有机物弱疏水性有机物,其中亲水性有机物和疏水碱性有机物引起不可逆污染的比例较高。当跨膜压差超过70kPa时,超滤膜的比通量随着跨膜压差的升高变得更加严重。与中性条件相比,水溶液pH值在酸性条件下会加重超滤膜污染,并且造成的不可逆污染比例最高;而当pH值升高到10.5时,水中产生了碳酸钙沉淀,但造成的膜污染是最轻的,表明无机颗粒物对超滤膜的污染影响不大。投加Ca2+会对超滤膜比通量产生一定有利影响,并且降低不可逆污染的比例。超滤膜的截留分子量在10kDa-100kDa范围内时,不可逆污染的比例随膜孔径的变大而升高。投加KMnO_4对BAF工艺出水进行氧化预处理,对改善超滤膜比通量的下降和减少不可逆污染比例效果不明显。投加PAC进行吸附预处理,对改善超滤膜比通量的下降效果明显,且超滤膜不可逆污染比例较投加KMnO4药剂时低。PAC对BAF工艺出水中的DOC和UV254去除效果非常明显,对水中的富里酸类物质、腐殖酸类物质和微生物代谢产物去除率达到40%-60%。投加PACl进行混凝预处理,对改善超滤膜比通量的下降效果非常明显,不可逆污染比例下降也较为明显。三种预处理效果为PACl混凝预处理PAC吸附预处理高锰酸钾氧化预处理。
[Abstract]:Membrane technology has many advantages in the field of municipal water supply and sewage treatment. It is of great significance to study the causes of membrane fouling and the control methods of membrane fouling in order to delay the service life of membrane and reduce the running cost. Based on Pinggu Recycling Water Plant and Reclamation Water Utilization Project of Beijing Bi-water Technology Co., Ltd., the mechanism of membrane fouling and the control of membrane fouling during the effluent treatment of biological aerated filter were studied in this paper. The main conclusions are as follows. The removal rate of DOC UV254) and CODS-Cr2) concentration in the effluent of BAF process is not high, only about 5%, the turbidity removal effect is very good, the turbidity of effluent is kept below 0.2NTU, and the removal rate of particulate matter is up to 95%. Membrane fouling was found in the two modes of constant pressure filtration and constant flux filtration. The results of SEM scanning electron microscopy showed that the pollutants deposited on the surface of ultrafiltration membrane were deposited in the effluent from the process of filtration. The thick filter cake layer. BAF process produced different hydrophilic components in the effluent, which caused different pollution degree to the ultrafiltration membrane. The contribution of the four components to ultrafiltration membrane fouling is hydrophilic organic matter hydrophobic alkaline organic matter hydrophobic acid organic weak hydrophobic organic matter among which hydrophilic organic matter and hydrophobic alkaline organic matter cause irreversible pollution. When the transmembrane pressure difference exceeds 70kPa, the specific flux of the ultrafiltration membrane becomes more serious with the increase of the transmembrane pressure difference. Compared with the neutral condition, the pH value of the aqueous solution will aggravate the ultrafiltration membrane fouling under acidic conditions, and the irreversible fouling ratio will be the highest, while when the pH value increases to 10.5, the calcium carbonate precipitate in the water will be produced, but the membrane fouling will be the least. The results showed that inorganic particles had little effect on ultrafiltration membrane fouling. Adding Ca2 to UF membrane can influence the specific flux of UF membrane and reduce the ratio of irreversible fouling. When the molecular weight of ultrafiltration membrane is in the range of 10kDa-100kDa, the ratio of irreversible fouling increases with the increase of membrane pore size. The addition of KMnO_4 to the oxidation pretreatment of the effluent from the BAF process has no obvious effect on the improvement of the specific flux of the ultrafiltration membrane and the reduction of the ratio of irreversible pollution. The adsorption pretreatment with PAC has obvious effect on improving the decrease of specific flux of ultrafiltration membrane, and the ratio of irreversible fouling of ultrafiltration membrane is lower than that of adding KMnO4 reagent. The removal effect of DOC and UV254 in the effluent of BAF process is very obvious. The removal rates of fulvic acids, humic acids and microbial metabolites in water reached 40-60. The effect of adding PACl in coagulation pretreatment is very obvious to improve the specific flux of ultrafiltration membrane, and the ratio of irreversible pollution is also obvious. The three pretreatment effects are PACl coagulation pretreatment, PAC adsorption pretreatment, potassium permanganate oxidation pretreatment.
【学位授予单位】：清华大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X703

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