超滤—反渗透双膜法在海水淡化中的应用研究

发布时间：2017-12-27 19:26

本文关键词：超滤—反渗透双膜法在海水淡化中的应用研究　出处：《清华大学》2015年硕士论文　论文类型：学位论文

【摘要】：为了满足青岛市自来水和工业用水的需求以及海水的综合利用,将在青岛市建设规模为10万m3/d的海水淡化项目,作为国内最大的海水淡化项目之一,需要对渤海湾海水水质及海水淡化工艺进行试验研究。本试验以渤海湾海水作为进水水源,经过盘片过滤器后进入超滤膜进行处理,考察超滤在该种原水时对污染物的去除率和运行的稳定性,进一步考察超滤产水供给反渗透系统时,反渗透膜对污染物的去除效果及运行稳定性,验证超滤-反渗透双膜法在海水淡化应用上的可行性,所得到的试验结果为进一步工程设计提供参考。本研究取得了以下主要成果:在不同通量情况下,超滤过程对海水中污染物的平均去除率分别为CODMn(化学需氧量)20.3%、TOC(总有机碳)5.64%、浊度98.1%,超滤产水SDI(淤积指数)值为1~3,平均值为2.2。分别在三种过滤周期、三种通量和三种CEB(化学强化反洗)周期下考察超滤运行稳定性、跨膜压差上升速率以及CEB对跨膜压差的恢复情况等。结果表明过滤周期为45分钟时超滤运行稳定且渗透率下降速率最低;通量为85L/(m2.h)时,在23、31和46个反洗周期下超滤运行均很稳定,且CEB后跨膜压差均能恢复到接近初始值。通过在线投加絮凝剂FeCl3,来控制跨膜压差,结果表明投加量在0~1.0mg/L之间时絮凝剂对控制跨膜压差的升高有积极作用,但是过量的絮凝剂的投加会导致超滤膜的污染,通过电子显微镜和X射线光谱分析对比膜污染前后表面成分,发现污染膜表面的Fe、Si、Ca、Mg成分偏高,这与絮凝剂的投加有一定关系且膜表面存在无机盐结垢的情况。在试验期间反渗透有着良好的处理效果,平均产水电导率为130μs/cm,平均产水硼为0.33 mg/L,脱盐率在95%以上。反渗透运行通量为15 L/(m2?h),阻垢剂投加量在1~1.3 mg/L时系统运行稳定,产水的平均回收率达到43.2%。另外,通过对运行成本的分析,显示超滤-反渗透双膜法工艺的运行吨水成本在3.75元/m3左右,低于热法的制水成本。项目产品水作为青岛市居民饮用水和青岛碱厂工艺用水,反渗透浓水作为青岛碱厂生产工艺用水,实现了海水淡化与工业制碱的一体化。
[Abstract]:In order to meet the Qingdao city tap water and industrial water demand and the comprehensive utilization of seawater, the 100 thousand m3/d seawater desalination project in the construction scale of Qingdao City, as the largest desalination project in the Gulf of Bohai, to the quality of sea water and seawater desalination process test research. In this experiment, the waters of the Gulf of Bohai as the influent water, through the disc filter after entering the ultrafiltration process, the study of ultrafiltration in raw water on the pollutant removal rate and the stability of operation, further study of ultrafiltration waterproduction water supply reverse osmosis system, removal efficiency and operation stability of the pollutants in the reverse osmosis membrane, ultrafiltration and verification RO desalination method in the feasibility of the application of the results obtained to provide reference for further engineering design. The main achievements of this study are as follows: under different fluxes, the average removal rate of pollutants in seawater is CODMn (chemical oxygen demand) 20.3%, TOC (total organic carbon) 5.64%, turbidity 98.1%, and ultrafiltration water production SDI (sedimentation index) is 1~3, and the average value is 2.2. The operational stability of ultrafiltration, the rising rate of transmembrane pressure rise and the recovery of CEB to transmembrane pressure were investigated in three filtration cycles, three fluxes and three CEB cycles. The results show that when the filtration period is 45 minutes, the operation of ultrafiltration is stable and the rate of permeability decline is the lowest. When the flux is 85L/ (m2.h), the operation of ultrafiltration is stable at 23, 31 and 46 backwash cycles, and the transmembrane pressure difference after CEB can be restored to the initial value. Through online flocculant FeCl3, to control the transmembrane pressure. The results showed that the dosage of flocculant in 0~1.0mg/L between control of transmembrane pressure rise has a positive effect, but excessive flocculant will lead to membrane pollution by electron microscope and X ray spectrum analysis of components before and after comparison of membrane fouling the surface of the membrane surface contamination is found Fe, Si, Ca, Mg component is high, and the flocculant with inorganic salt scaling relation and the membrane surface of the. During the test, the reverse osmosis has a good treatment effect. The average water yield is 130 u s/cm, the average water producing boron is 0.33 mg/L, and the desalination rate is over 95%. The flux of reverse osmosis is 15 L/ (M2? H). The system runs steadily when the dosage of scale inhibitor is 1~1.3 mg/L, and the average recovery rate of water production reaches 43.2%. In addition, through the analysis of the operation cost, it shows that the cost of the operation ton water of the ultrafiltration and reverse osmosis double membrane process is about 3.75 yuan /m3, which is lower than the cost of the heat production. The product of the project of water for drinking water in Qingdao city and Qingdao soda plant process water, reverse osmosis water as Qingdao soda production process water, realize the integration of seawater desalination and industrial production base.
【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】：P747

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