Water shortage is a worldwide problem which leads to rapid developments in technologies targeting reclamation and seawater desalination. Currently, reverse osmosis (RO) appears to be the most efficient way for producing fresh water from seawater with an average salinity of 3.5 wt% and brackish water with a salinity of 0.05-3 wt% mainly due to its low cost and high salt rejection over 99.5%. However, the driving force for RO process is the pressure difference between the feed and permeate sides of the RO membrane. To overcome the osmosis pressure, a very high feed pressure is mandatory to be able to squeeze water from concentrated salt solution. Therefore, a typical water production rate is only 50% for seawater RO desalination process. It not only limits the productivity of RO, but also produces high concentrated seawater that may cause seriously environmental issues.
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