A reverse osmosis concentrated seawater treatment system and method

Abstract

The invention discloses a reverse osmosis concentrated seawater processing system and a method. According to the method, the reverse osmosis concentrated seawater processing system is adopted; reverse osmosis concentrated seawater is delivered through a security filter successively for filtering, pH value is adjusted, pressure is increased, and obtained pretreated water is delivered through a nanofiltration membrane element, a resin softening device, and a heating tank so as to obtain a heat material liquid; the heat material liquid is delivered through a membrane distillation element so as to obtain fresh water and a concentrated material liquid; the concentrated material liquid is subjected to treatment via bipolar membrane electrodialysis so as to obtain an acidic solution and an alkali solution. The method is high in softening efficiency; membrane distillation operation temperature is low; evaporation area is large; the quality of obtained fresh water is high; internal recovering of steam latent heat is realized; influence of concentration on membrane distillation is low, so that deep condensation is capable of obtaining the concentrated material liquid beneficial for high efficiency operation of bipolar membrane electrodialysis, the value of the obtained acidic solution and the alkali solution is higher than that of solid salt. Compared with the prior art, the method possesses following advantages: energy is saved; the production process is safer, and is more friendly to the environment; the obtained acid and alkali can be used for nanofiltration scale inhibition and resin regeneration, so that the adding amount of chemical agents of the whole system is reduced, and cost is reduced.

Description

technical field

[0001] The invention relates to water treatment technology, in particular to a reverse osmosis concentrated seawater treatment system and method. Background technique

[0002] Seawater desalination has become an important way to open up water sources, and the recovery rate of seawater desalination is generally only 40%-50%. At present, concentrated seawater is generally discharged directly back to the sea without treatment. The discharge of concentrated seawater has caused a huge waste of resources and damage to the marine environment. Therefore, how to deal with concentrated seawater is a problem that must be faced in the sustainable development of seawater desalination industry.

[0003] Patent Nos. 201110411270.8, 201110069347.8 and 201210150064.0 disclose some reverse osmosis concentrated seawater treatment methods, such as using dosing, ion membrane, ion exchange resin and other methods as pre-treatment to remove calcium and magnesium ions or extract cal...

Examples

Embodiment 1

[0036] A method for treating concentrated seawater by reverse osmosis, comprising the steps of:

[0037] (1) Use above-mentioned a kind of reverse osmosis concentrated seawater treatment system;

[0038] (2) Reverse osmosis concentrated seawater (salt content 45887mg / L, pH 8.0, in which Ca 2+ 521mg / L, Mg 2+ 1620mg / L) into the security filter 1 (using a filter element with a filtration accuracy of 5 μm) to filter, remove particulate impurities, and obtain pretreated product water;

[0039] (3) After adjusting the pH to 4 with the acid fed from the acid dosing pump 22, the pretreated water is pressurized to 1.5MPa by the high-pressure pump 2, and passed into the nanofiltration membrane element 3 (using XCN model) for primary softening treatment to remove hardness ions in the range of 70% to 90% and organic matter with a molecular weight of more than 200 to obtain nanofiltration soft water (nanofiltration soft water has a salt content of 38100mg / L, wherein Ca 2+ 196mg / L, Mg 2...

Embodiment 2

[0046] A method for treating concentrated seawater by reverse osmosis, comprising the steps of:

[0047] (1) Use above-mentioned a kind of reverse osmosis concentrated seawater treatment system;

[0048] (2) Reverse osmosis concentrated seawater (salt content 47620mg / L, pH 8.0, in which Ca 2+ 572mg / L, Mg 2+ 1690mg / L) into the security filter 1 (using a filter element with a filtration accuracy of 5 μm) to filter, remove particulate impurities, and obtain pretreated product water;

[0049] (3) Adjust the pH to 2 with the acid fed from the acid dosing pump 22 for the pretreated product water, pressurize it to 2.5 MPa through the high pressure pump 2, and pass it into the nanofiltration membrane element 3 (using HYDRApro model or DK model) Perform primary softening treatment to remove hardness ions in the range of 70% to 90% and organic matter with a molecular weight above 200 to obtain nanofiltration soft water (the salt content of nanofiltration soft water is 39120mg / L, where...

technical field

[0001] The invention relates to water treatment technology, in particular to a reverse osmosis concentrated seawater treatment system and method. Background technique

[0002] Seawater desalination has become an important way to open up water sources, and the recovery rate of seawater desalination is generally only 40%-50%. At present, concentrated seawater is generally discharged directly back to the sea without treatment. The discharge of concentrated seawater has caused a huge waste of resources and damage to the marine environment. Therefore, how to deal with concentrated seawater is a problem that must be faced in the sustainable development of seawater desalination industry.

[0003] Patent Nos. 201110411270.8, 201110069347.8 and 201210150064.0 disclose some reverse osmosis concentrated seawater treatment methods, such as using dosing, ion membrane, ion exchange resin and other methods as pre-treatment to remove calcium and magnesium ions or extract cal...

Examples

Embodiment 1

[0036] A method for treating concentrated seawater by reverse osmosis, comprising the steps of:

[0037] (1) Use above-mentioned a kind of reverse osmosis concentrated seawater treatment system;

[0038] (2) Reverse osmosis concentrated seawater (salt content 45887mg / L, pH 8.0, in which Ca 2+ 521mg / L, Mg 2+ 1620mg / L) into the security filter 1 (using a filter element with a filtration accuracy of 5 μm) to filter, remove particulate impurities, and obtain pretreated product water;

[0039] (3) After adjusting the pH to 4 with the acid fed from the acid dosing pump 22, the pretreated water is pressurized to 1.5MPa by the high-pressure pump 2, and passed into the nanofiltration membrane element 3 (using XCN model) for primary softening treatment to remove hardness ions in the range of 70% to 90% and organic matter with a molecular weight of more than 200 to obtain nanofiltration soft water (nanofiltration soft water has a salt content of 38100mg / L, wherein Ca 2+ 196mg / L, Mg 2...

Embodiment 2

[0046] A method for treating concentrated seawater by reverse osmosis, comprising the steps of:

[0047] (1) Use above-mentioned a kind of reverse osmosis concentrated seawater treatment system;

[0048] (2) Reverse osmosis concentrated seawater (salt content 47620mg / L, pH 8.0, in which Ca 2+ 572mg / L, Mg 2+ 1690mg / L) into the security filter 1 (using a filter element with a filtration accuracy of 5 μm) to filter, remove particulate impurities, and obtain pretreated product water;

[0049] (3) Adjust the pH to 2 with the acid fed from the acid dosing pump 22 for the pretreated product water, pressurize it to 2.5 MPa through the high pressure pump 2, and pass it into the nanofiltration membrane element 3 (using HYDRApro model or DK model) Perform primary softening treatment to remove hardness ions in the range of 70% to 90% and organic matter with a molecular weight above 200 to obtain nanofiltration soft water (the salt content of nanofiltration soft water is 39120mg / L, where...

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