Climate change and the rapid development of global industry and agriculture have made the problem of lack of fresh water increasingly serious, and the supply of fresh water is becoming increasingly tense, so that some coastal cities are also seriously short of water. The water crisis poses an unprecedented demand for seawater desalination. Membrane desalination equipment is a process in which seawater enters through a semi-permeable spiral membrane under pressure, the excess salt and minerals in the seawater are blocked on the high pressure side and are drained out with concentrated seawater, and the fresh water is coming out from the low pressure side.

According to the National Bureau of Statistics, the total amount of freshwater resources in China was 2830.6billion cubic meters in 2015, accounting for about 6% of global water resources, ranking fourth in the world. However, the per capita fresh water resources are only 2,300 cubic meters, which is only 1/35 of the world average, and there is a shortage of natural fresh water resources. With the acceleration of industrialization and urbanization, freshwater pollution is serious mainly due to industrial wastewater and urban domestic sewage. Desalination of seawater is expected to be a major direction for supplementing high-quality drinking water. China’s seawater desalination industry use accounts for 2/3 of the total. As of December 2015, seawater desalination projects 139 have been built nationwide, with a total scale of 1.0265million tons/day. Industrial water accounts for 63.60%, and residential water accounts for 35.67%. The global desalination project mainly serves residential water (60%), and industrial water only accounts for 28%.

An important goal of the development of seawater desalination technology is to reduce operating costs. In the composition of operating costs, electric energy consumption accounts for the largest proportion. Reducing energy consumption is the most effective means to reduce seawater desalination costs.