Due to over 70% of the world’s population residing within 120 kilometers of the ocean, seawater desalination technology has rapidly been applied in many countries and regions for getting fresh water for human daily uses and industrial uses.

In the beginning, Human used the fireplace on the ship to boil seawater to produce fresh water during their long voyages. Heating seawater to produce water vapor, cooling and condensing to obtain pure water is a daily experience and the beginning of seawater desalination technology, with the devoloping of the technology and experience, until now, there are more than 20types seawater desalination technologies, including reverse osmosis, low multi efficiency, multi-stage flash evaporation, electrodialysis, pressurized steam distillation, dew point evaporation, hydropower cogeneration, hot film cogeneration, and the use of nuclear energy, solar energy, wind energy, tidal energy seawater desalination technologies, as well as multiple pre-treatment and post-treatment processes such as microfiltration, ultrafiltration, and nanofiltration.

Among them, low multi effect distillation, multi-stage flash evaporation, and reverse osmosis membrane method are the mainstream technologies worldwide. Low multi efficiency has the advantages of energy conservation, low requirements for seawater pretreatment, and high quality of desalinated water; The reverse osmosis membrane method has the advantages of low investment and low energy consumption, but it requires high requirements for seawater pretreatment; The multi-stage flash evaporation method has advantages such as mature technology, reliable operation, and large device output, but it has high energy consumption. It is generally believed that low efficiency distillation and reverse osmosis membrane methods are the future directions.

Nowadays, RO seawater dealination are much more popular to be used for making fresh water for offshore town, city living and also for seaside oil field and others, with its advantages as followings:

1. Lower energy consumption and lower operating electricity costs

-After equipping the energy recovery device ERD, the system’s power consumption is about * * 2.5-3.5 kWh/m ³ * *, which is only about one-third of that of thermal distillation

-No need to heat seawater, no consumption of steam or boiler fuel, only electricity, convenient for supporting new energy sources such as photovoltaics and wind power, with lower carbon emissions

2. Good desalination performance and stable effluent quality

-The salt retention rate of seawater reverse osmosis membrane can reach over 99.5%, and it can simultaneously remove dissolved salts, heavy metals, bacteria, viruses, colloids, and organic matter

-The TDS of the produced water can be reduced to 200-500 mg/L, and after simple mineralization and disinfection, it can meet the requirements of domestic drinking water or industrial pure water

3. Modular design, flexible scale, and small footprint

-Modular assembly of standard membrane shells and membrane components, capable of ranging from small containerized island devices (producing tens of tons per day) to large municipal water plants (producing hundreds of thousands of tons per day)

-The equipment is compact and occupies a much smaller area than the thermal method; Expansion is simple, and membrane groups can be added in stages without the need to build all the factories at once ..