Forward osmosis and reverse osmosis (FO-RO) coupled novel seawater desalination process

Abstract

The invention discloses a forward osmosis and reverse osmosis (FO-RO) coupled novel seawater desalination process. The process comprises the following steps: 1, a raw material solution (seawater) of an FO system enters an FO3 system from a water flow channel 1 at a speed of 2700L / h through a water pump, and meanwhile, a draw solution (2 Mol / L sodium chloride solution) of the FO system enters a draw solution side of an FO1 system through a flow channel 5; 2, the seawater obtained after FO3 concentration enters the raw material liquid side of FO2 from a flow channel 2, and a sodium chloride solution obtained after FO1 dilution enters the absorbing liquid side of the FO2from a flow channel 6; 3, the seawater obtained after FO2 is further concentrated enters the raw material liquid side of theFO1 system from a flow channel 3, a sodium chloride solution further diluted by the FO2 enters the absorbing liquid side of the FO3, and finally, the seawater concentrated by the FO1 flows out of a flow channel 4, a sodium chloride solution diluted by FO3 flows out of the absorbing liquid side from a flow channel 8, and the seawater enters a buffer pool 1; and step 4, an RO system extracts the diluted sodium chloride solution in the buffer pool 1 through a high-pressure pump. Forward osmosis membrane pollution can be effectively controlled through a physical method.

Description

technical field [0001] The invention relates to the fields of environmental engineering, marine engineering, interface chemistry and the like, and in particular relates to a novel seawater desalination process coupled with forward osmosis and reverse osmosis (FO-RO). Background technique [0002] 1. Forward osmosis technology. [0003] Forward osmosis is a natural phenomenon, which refers to the flow of water from the side area with higher water chemical potential (or lower osmotic pressure, that is, low salinity) to the lower water chemical potential (or higher osmotic pressure, i.e. high salinity)-side zone process. Two solutions with different osmotic pressures are placed on both sides of the selectively permeable membrane, one is the feed solution with lower osmotic pressure, and the other is the draw solution with higher osmotic pressure ( Draw solution), forward osmosis is to use the osmotic pressure difference of the solution on both sides of the membrane as the dri...

AI Technical Summary

Problems solved by technology

However, the problem of membrane fouling has always been a difficulty that plagues the application of reverse osmosis membrane water treatment systems

[0028] 1. High energy consumption of thermal seawater desalination process

[0029] Thermal seawater desalination, multi-effect evaporation (MED) and multi-stage flash evaporation (MSF) all have the problem of high energy consumption, which makes the cost of seawater desalination remain high. At present, it is mainly used in oil-rich and freshwater resources such as the Gulf region. barren areas

[0030] In addition, MED fouling is serious, which may easily cause uneven heating of the equipment and cause equipment damage

However, MSF has the disadvantage of low heat transfer efficiency, which reduces water production efficiency and increases desalination costs

[0031] 2. Reverse osmosis membrane seawater desalination is plagued by membrane fouling (especially biological fouling)

However, biofouling of reverse osmosis membranes, especially during algae blooms, remains a major desalination challenge in Saudi Arabia to date

Membrane biofouling is caused by the attachment, growth and reproduction of microorganisms and highly viscous organic matter in seawater on the surface of the reverse osmosis membrane, which makes a layer of biomass on the surface of the reverse osmosis membrane, resulting in the water flux of the reverse osmosis membrane (per hour per hour) The water production rate of the square meter membrane) decreases, the power of water production increases (energy consumption increases), and the service life of the membrane is shortened, resulting in an increase in the cost of water production

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