There are more than 20 kinds of seawater desalination
technologies in the world, including reverse osmosis, low multiple-effect, multi-stage flash, electrodialysis, pressure steam distillation, dew point evaporation, hydropower cogeneration, thermal film cogeneration and the use of nuclear energy, solar energy, wind energy , tidal energy seawater desalination technology, etc., as well as a number of pretreatment and post-treatment processes such as microfiltration, ultrafiltration, and nanofiltration.
From the perspective of large classification, it is mainly divided into two categories: distillation method (thermal method) and membrane method. Among them, low multiple-effect distillation method, multi-stage flash method and reverse osmosis membrane method are the mainstream technologies in the world. Generally speaking, low multi-effect has the advantages of energy saving, low requirements for seawater pretreatment, and high quality of desalinated water; reverse osmosis membrane method has the advantages of low investment and low energy consumption, but requires high seawater pretreatment; It has the advantages of maturity, reliable operation and large output of the device, but the energy consumption is high.
It is generally believed that the low multiple-effect distillation method and the reverse osmosis membrane method are the future directions. It is estimated that during the "Twelfth Five-Year Plan" period, China's seawater desalination will reach 1.5-2 million tons per day, which is three or four times the existing production capacity, and the investment scale will reach about 20 billion yuan.