纳滤和膜蒸馏处理海水淡化浓盐水的研究

发布时间：2018-10-08 19:14

【摘要】：目前,海水淡化过程产生的浓海水直接排放将对生态环境造成严重影响。我国沿海地区水资源短缺、土地资源紧张、近岸海域环境迫切需要得到保护,处理海水淡化浓盐水势在必行。本文主要研究了纳滤和膜蒸馏处理海水淡化浓盐水,设计了日处理10吨海水淡化浓盐水资源利用工艺装置。具体结论如下：首先研究了纳滤处理海水淡化浓盐水,讨论了操作压力和进料浓度对纳滤膜分离性能的影响。实验结果表明在温度一定的条件下,纳滤膜渗透通量、系统脱盐率、系统回收率、二价离子截留率均随操作压力的增大而增大,随进料浓度的增大而减小。对于6wt.%的浓盐水,在较优化的工艺条件下,纳滤过程渗透通量达到47.9L/(m2·h), Ca2+、 Mg2+、SO42-的截留率达到37.8%、57.8%、82.9%,系统回收率达到57.6%,高于纳滤膜一般规定的回收率。其次研究了真空膜蒸馏处理海水淡化浓盐水,讨论优化了膜蒸馏的各种工艺参数,包括进料液温度,进料液浓度,渗透侧压强和膜表面流量。实验结果表明在其他条件一定的情况下,膜蒸馏渗透通量随料液温度升高而增大,随进料液浓度增大而减小,随渗透侧压强增大而减小,随膜表面流速增大而增大。此外,还进行了真空膜蒸馏浓缩结晶实验：以起始浓度为150g/L的氯化钠溶液和200g/L的硫酸钠溶液作为母液来考察膜蒸馏装置浓缩结晶性能。在较优化的工艺条件下,6wt.%的浓盐水膜蒸馏过程通量达到33.0L/(m2·h),且表现出近100%的截留率。最后,根据纳滤和真空膜蒸馏的实验结果,设计了日处理10吨海水淡化浓盐水资源利用工艺装置,装置采用超滤-纳滤-真空膜蒸馏(UF-NF-VMD)相耦合的工艺流程。结果表明,该中试装置能有效处理海水淡化浓盐水。
[Abstract]:At present, the direct discharge of desalination will have a serious impact on the ecological environment. Because of the shortage of water resources and the shortage of land resources in the coastal areas of China, the environment of coastal waters needs to be protected urgently, so it is imperative to deal with desalination of concentrated salt water. In this paper, nanofiltration and membrane distillation were studied for desalination of desalinated concentrated brine, and a technological device for utilization of desalination of concentrated brine resources was designed for 10 tons of seawater desalination per day. The main conclusions are as follows: firstly, the effects of operating pressure and feed concentration on the separation performance of nanofiltration membrane were studied. The experimental results show that the permeation flux of nanofiltration membrane, system desalination rate, system recovery rate and bivalent ion rejection rate increase with the increase of operating pressure and decrease with the increase of feed concentration. For the concentrated brine of 6 wt.%, the permeation flux of the nanofiltration process reached 47.9L/ (m ~ 2 h), Ca2, Mg2 so _ 42-) under the optimized process conditions, and the retention rate of the nanofiltration process reached 37.8% and 57.8%, and the system recovery rate reached 57.6%, which was higher than the normal recovery rate of the nanofiltration membrane. Secondly, vacuum membrane distillation was studied to treat seawater desalination concentrated brine, and various technological parameters of membrane distillation were discussed and optimized, including feed liquid temperature, feed liquid concentration, osmotic pressure and membrane surface flow rate. The experimental results show that the permeation flux of membrane distillation increases with the increase of feed temperature, decreases with the increase of feed concentration, decreases with the increase of permeation pressure and increases with the increase of membrane surface velocity under certain other conditions. In addition, the concentrated crystallization experiments of vacuum membrane distillation were carried out. The concentrated crystallization properties of membrane distillation unit were investigated by using sodium chloride solution with initial concentration of 150g/L and sodium sulfate solution of 200g/L as mother liquor. Under the optimized conditions, the flux of 6 wt.% concentrated brine membrane distillation process reached 33.0L/ (m2 h),) and showed a rejection rate of nearly 100%. Finally, according to the experimental results of nanofiltration and vacuum membrane distillation, a process device for the utilization of concentrated brine resources for desalination of 10 tons of seawater per day was designed. The process of ultrafiltration, nanofiltration and vacuum membrane distillation (UF-NF-VMD) coupling process was adopted. The results show that the pilot plant can effectively treat desalination of concentrated salt water.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P747.1

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