膜蒸馏过程中污染膜的清洗

针对膜蒸馏法处理石化反渗透浓水的膜面污染物进行了分析及清洗工艺优化研究。在反渗透浓水温度为73℃、渗透侧真空度为-0.093 MPa的条件下进行膜蒸馏实验,实验后期膜通量衰减迅速,脱盐率基本保持在99.5%以上,产水p H基本稳定在6.5~7.0。膜面污染物的SEM表征结果显示,膜蒸馏的膜面污染主要为碳酸钙、硅酸钙、氢氧化镁结垢污染和氯化钠、氯化钾等盐类结晶污染。实验结果表明:分别以盐酸和去离子水为清洗液静态浸泡清洗污染膜时,污染物的去除效果最好,Na OH溶液次之,草酸最差;分别采用盐酸和去离子水动态清洗污染膜,膜通量和脱盐率均能恢复到初始水平,随运行时间的延长,经去离子水清洗后膜的膜通量出现衰减。

Cleaning of Membrane Polluted in Membrane Distillation Process

The membrane fouling in membrane distillation treatment of reverse osmosis concentrated water from petrochemical wastewater was analyzed,and the cleaning process was optimized. When the membrane distillation experiment was carried out under the conditions of reverse osmosis concentrated water temperature 73 ℃ and vacuum degree -0.093 MPa,the desalination rate of the system was above 99.5%, and the product water pH was about 6.5-7.0,although the membrane flux decreased rapidly at later stage of the experiment. The SEM photograph shows that the membrane fouling in membrane distillation is mainly consisted of calcium carbonate,calcium silicate,magnesium hydroxide,sodium chloride and potassium chloride,and so on. The experiment results show that：In the static soak cleaning experiment,the fouling removal effects are the best in hydrochloric acid and deionized water,worse in NaOH solution,and the worst in oxalic acid;In the dynamic cleaning experiment,the membrane flux and desalination efficiency are recovered to the initial level by using hydrochloric acid and deionized water,while the flux of the membrane cleaned with deionized water is decreased with the extension of operating time.