Forward-osmosis strategy and chemical cleaning of seawater desalination reverse osmosis membranes |
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| Authors: | Ming TAN Wenguang WANG Xiaodong ZHANG Hongwu ZHAO Yang ZHANG Xingtao YANG |
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| Affiliation: | 1.College of Environment and Safety Engineering, Qingdao University of Science & Technology, Qingdao 266042, Shandong, China;2.Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, Shandong, China;3.Qingdao Befesa Seawater Desalination Co. Ltd. , Qingdao 266043，Shandong, China |
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| Abstract: | In order to settle the membrane fouling of reverse osmosis membranes in seawater desalination process, this study reported a novel strategy based on forward-osmosis process and discussed the effects of different factors like different cleaning combination among reverse osmosis product, simulated reverse osmosis concentrate and simulated seawater, as well as cleaning time on the membrane permeate flux and salt rejection. For irreversible fouling, the effects of different chemical cleaning agents, immersion time and concentration were also investigated in this study. The results exhibited that the cleaning combination between diluted water and simulated reverse osmosis concentrate possessed the best cleaning performance in the process of forward-osmosis cleaning. Such approach also enhanced normalized flux from 9.48 L/(m2·h·MPa) to 13.6 L/(m2·h·MPa) and enhanced NaCl rejection from 80.59% to 92.80%. Furthermore, the normalized flux was enhanced from 9.48 L/(m2·h·MPa) to 14.3 L/(m2·h·MPa) and NaCl rejection was also enhanced from 80.59% to 96.27% after soaking in 2%(mass) citric acid solution for 2h, soaking with 1%(mass) ethylenediamine tetra-acetic acid tetrasodium salt and 0.3%(mass) sodium tripolyphosphate solution for 1.5 h. According to the result of SEM images and AFM images, the forward-osmosis cleaning strategy could not cause the damage of selective layer of membrane surface and caused the drop of inorganic and organic fouling on the membrane surface. Hence, cleaning fouled RO membranes by such approach could prolong the chemical cleaning cycle and reduce the amount of chemical cleaning agent, which has certain industrial application perspectives. |
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| Keywords: | membrane separation desalination forward-osmosis cleaning seawater desalination reverse osmosis |
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