Study On The Treatment Of UF Technology In Taihu Raw Water And Treatment Of Sudden Aniline Pollution

According to the drinking water quality standard implemented in 2007, the water quality of tap water is further improved, National sudden water pollution incidents occurred frequently, and Taihu, an important source of drinking water, is also threatened. The new water treatment technology to ensure the safety of drinking water is increasingly urgent. As the core of the third generation of water purification technology, ultrafiltration technology has a bright future in the field of drinking water treatment. However, the research on ultrafiltration technology did not receive enough attention. Membrane fouling in the process of ultrafiltration is a serious obstacle for the promotion of the ultrafiltration technology to the market. At the same time, the flux of ultrafiltration in the operation process is often determined according to the experience of the staff with little scientific theoretical guidance, which will cause the problem of low production and other issues. In recent years, the sudden water pollution accident, especially the leakage of aniline?such as Changzhi Shanxi aniline leakage accident? is a serious threat to the drinking water safety.In order to explore the feasibility of application of ultrafiltration technology for treatment of source water in Taihu, this paper analyzed the operating flux, membrane fouling factors, and the effect of treatment of source water in Taihu, and explored the characteristics of the effluent of ultra filtration system according to the indexes such as The transmembrane pressure?TMP?, permanganate index, DOC, UV₂₅₄, molecular weight distribution, aniline and etc. The removal efficiency of aniline by ultrafiltration combination process(powdered activated carbon?PAC?- potassium permanganate?KMnO₄?- ultrafiltration was studied to determine the feasibility of the process to deal with the sudden pollution of aniline. The main conclusions are as follows:In order to determine the flux of ultrafiltration membrane, the critical flux was firstly measured. The result shows that the critical flux of the device ranges from²7 to30 l/m²·h, and the maximum sustainable flux is 54 l/m²·h. At last, by comparing the variation of the transmembrane pressure under critical flux and maximum sustainable flux, the stability of effluent water quality and the operating condition of ultrafiltration device under extreme conditions, the operating flux of ultrafiltration device is 54 l/m²·h in Taihu.In recent years, the water quality of Taihu River Basin has been improved, but under the situation of sudden water pollution incidents and increasingly restrictsanitary standard for drinking water, the study of new water treatment technology to protect the safety of drinking water requirements become increasingly urgent.Ultrafiltration technology is the core of the third generation water purification technology, and shows its vitality in the field of drinking water treatment. However,the membrane fouling problem is a serious obstacle to the promotion of ultrafiltration technology. The study of factors that affect membrane fouling, and the measurements which may control it effectively is an urgent problem to be solved. At the same time,due to the lack of scientific theoretical guidance, the flux of ultrafiltration in the operation process is often determined according to the experience of the staff, which will lead to the low production of water, over-fast membrane pollution and other issues. In recent years, the sudden water pollution incidents occurred frequently,especially the aniline leakage accident, which greatly influenced the production and living of people. In view of these problems, the paper has carried out the research on factors of ultrafiltration membrane fouling, the optimization of the operating flux, the removal effect of aniline by the ultrafiltration after the using of powdered activated carbon adsorption combined with potassium permanganate oxidation and its economic feasibility. Membrane fouling analysis shows that raw water quality, input water temperature and operating flux of UF system will affect the membrane fouling in different degree. With the rising of raw water turbidity, organic matter concentration and the decline of input water temperature, the operating pressure of the ultrafiltration system will increase, and the growth rate of transmembrane pressure difference during a backwash cycle will also increase relatively. But after backwashing, the operation pressure can be recovered to its original state. The pressure will increase rapidly when the running flux is raised to H- 81L/m², and it is also difficult to recover to the state before filtering. Moreover with the increase of operating time, the running pressure will reach the warning value system.Molecular weight distribution of TOC response value in Taihu is mainly composed of small molecules whose UV response is relatively weak. While the TOC response value of large molecular substance is much lower, and the absorption of the ultraviolet was stronger. The molecular weight distribution of UF effluent was similar to that of water source in Taihu, the difference appears only when the molecular weight of TOC response values ranges from 900 to 1100 or more than 10000. The effluent turbidity of ultrafiltration system was stable at 0.1NTU, the effluent of permanganate index stable between 2mg/L?3mg/L, the concentration of DOC isstable at 3mg/l?4mg/l. The removal effect of ammonia nitrogen and UV₂₅₄ was not obvious. The effluent water quality of UF is equal to that of sand filter, but the sand filter has good removal effect on ammonia nitrogen, and the concentration of ammonia nitrogen in the water is less than 0.02 mg/L.In the removal of pollutants in the raw water, the effect of UV is poor, and UV₂₅₄ did not change much as it is in raw water.The pollutants in the raw water are mainly composed of small and medium molecular organic matter, whose TOC response value is not removed ideally. The removal rate are 0.81% and 9.57% respectively. The removal rate of organics which have ultraviolet absorption ability is especially low?carbon filter: 69.92%, 88.47%, ultrafiltration: 19.28%, 60.87%?, the TOC concentration of ultrafiltration effluent can only reach the level of the sand filter.In response to the sudden aniline pollution incident, the thesis firstly determine adding amount of powdered activated carbon and Permanganate Potassium through microscale experiment. Test results show that 60mg/L powdered activated carbon can be added firstly when the amount of aniline in raw water of exceeded 5 times compared with standard. And after 15 minutes, adding 2.4 mg/L potassium permanganate can keep the content of aniline within standard. Secondly, after adding powder activated carbon and potassium permanganate, to optimize its dosage the test further dealt the water with ultrafiltration. The results show that if the adding of powder activated carbon is decreased to 5mg/L, the concentration of aniline can be controlled within the standard after ultrafiltration. And then through analyzing effluent dealt by the combination process of ultrafiltration, direct ultrafiltration and ozone activated carbon process currently using in water plant, the test found out that the effluent turbidity of the combined process is better than that of the ozone activated carbon process. There is no obvious differences on rest indexes which can meet the safety requirements of drinking water.This paper have studied the membrane fouling factor, the flux of the membrane and the treatment effect of ultrafiltration technology for water treatment in Taihuand,and provided a reasonable solution for the stable operation of the ultrafiltration device.The effect and characteristics of ultrafiltration on the treatment of water in Taihu are also clarified. At the same time, the research on the emergency plan for the sudden water pollution of aniline was carried out, and the method for controlling the concentration of aniline with the combination of the powder activated carbon adsorption, potassium permanganate oxidation and ultrafiltration process wasdeveloped. The research findings of the thesis can be seen as a technical reserve for waterworks which can be used to deal with water from Taihu through ultrafiltration technology.