Seawater desalination post-treatment system and method for preparing high-salinity drinking water

Abstract

The invention provides a seawater desalination post-treatment system and method for preparing high-salinity drinking water. The system comprises a desalted water subsystem, a desalted water subsystem and a mixing device, the desalted water subsystem is used for converting seawater into fresh water, and the desalted water subsystem is used for converting deep seawater containing mineral substances and rare elements into desalted water; an inlet of the mixing device is respectively connected with outlets of the desalted water subsystem and the desalted water subsystem, and the mixing device is used for uniformly mixing fresh water and desalted water to obtain high-salinity drinking water; the desalinated water subsystem comprises a seawater pretreatment device, a seawater desalination device, a first fresh water pump, a first chlorine adding device and a first sodium hydroxide adding device which are connected in sequence; the desalted water subsystem comprises a deep seawater pretreatment device, an electrodialysis seawater desalination device, a second fresh water pump, a second chlorine adding device and a second sodium hydroxide adding device which are connected in sequence. According to the scheme, the high-salinity drinking water is safely and effectively prepared at low cost by adopting seawater.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of seawater desalination water post-treatment, in particular to a seawater desalination post-treatment system and method for preparing high-mineralization drinking water. BACKGROUND

[0002] With the aggravation of global freshwater resource shortage, seawater desalination water as a new type of freshwater resource is increasingly valued. As an additional municipal water supply and backup emergency water source, seawater desalination water will be an important technical measure to ensure water safety in coastal areas and islands in the future. Seawater desalination water entering the pipe network as drinking water needs to be matched with mineralization post-treatment technology to reduce the impact on the pipe network. The mineralization degree of drinking water, as an important indicator to measure the total dissolved solid content in water, has a decisive influence on the quality of drinking water. Mineralization degree mainly reflects the content of minerals and inorganic salts in water, and is a key parameter for evaluating the quality of drinking water. High-mineralization drinking water has a good supplement effect on people with weak constitution, spleen and stomach deficiency and calcium deficiency, and can also be used for the treatment of specific diseases.

[0003] At present, the commonly used seawater desalination water post-treatment processes at home and abroad mainly include lime mineralization process, limestone mineralization process and blending process. The lime mineralization process can increase the water hardness, but cannot increase the carbonate alkalinity, and also needs to pre-inlet carbon dioxide or add sodium carbonate (or sodium bicarbonate) to increase the carbonate concentration in water. The limestone mineralization process is to introduce desalination water into a mineralization reactor containing limestone, and release calcium ions and carbonate ions into water through the dissolution of limestone. In order to promote the dissolution of calcium carbonate, the desalination water needs to be acidified with carbon dioxide first. At present, liquid CO2 is mainly used to acidify desalination water after vaporization, and the treatment cost is high. For preparing high-mineralization drinking water, the above two methods are not suitable, and it is urgent to develop a safe and effective, low-cost seawater desalination post-treatment system and method for preparing high-mineralization drinking water. SUMMARY

[0004] The present application provides a seawater desalination post-treatment system and method for preparing high-mineralization drinking water, which mixes desalination water with desalted water, can adjust the hardness of desalination water, and make the desalination water rich in minerals, and at the same time simplifies the post-treatment steps of desalination water.

[0005] In a first aspect, a seawater desalination post-treatment system for preparing high-mineralization drinking water comprises: a desalination water subsystem, a desalted water subsystem and a mixing device; the desalination water subsystem is used for converting seawater into fresh water, and the desalted water subsystem is used for converting deep seawater containing minerals and rare elements into desalted water; the inlet of the mixing device is connected with the outlets of the desalination water subsystem and the desalted water subsystem respectively, and the mixing device is used for mixing fresh water and desalted water uniformly to obtain high-mineralization drinking water.

[0006] The desalinated water subsystem includes a seawater pretreatment device, a seawater desalination device, a first freshwater pump, a first chlorine dosing device, and a first sodium hydroxide dosing device connected in sequence; the desalted water subsystem includes a deep seawater pretreatment device, an electrodialysis seawater desalination device, a second freshwater pump, a second chlorine dosing device, and a second sodium hydroxide dosing device connected in sequence.

[0007] In a second aspect, the present invention provides a seawater desalination post-treatment method for producing highly mineralized drinking water, comprising:

[0008] Determine the seawater pretreatment device and seawater desalination device based on the seawater quality detected;

[0009] Determining a deep seawater pretreatment device and an electrodialysis seawater desalination device based on the water quality of the deep seawater detected;

[0010] Determining the dosage of chlorine dioxide of the first chlorine dosing device and the dosage of sodium hydroxide of the first sodium hydroxide dosing device based on the desalinated water generated by the seawater desalination device;

[0011] Determining the dosage of chlorine dioxide of the second chlorine dosing device and the dosage of sodium hydroxide of the second sodium hydroxide dosing device based on the desalted water generated by the electrodialysis seawater desalination device;

[0012] The ratio of the fresh water to the desalted water is determined based on the target salinity of the highly mineralized drinking water, the detected salinity of the fresh water produced by the desalination water subsystem, and the salinity of the desalted water produced by the desalination water subsystem to obtain the highly mineralized drinking water.

[0013] Compared with the prior art, the present invention has at least the following beneficial effects:

[0014] This invention combines desalinated water from an electrodialysis unit with desalinated water from a seawater desalination unit to adjust the hardness of the desalinated water and simplify post-processing steps. Furthermore, a blending process, combining freshwater from two different desalination processes with highly mineralized desalinated water, ensures safe and hygienic water production. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 This is a schematic diagram of a seawater desalination post-treatment system for producing highly mineralized drinking water provided by one embodiment of the present invention;

[0017] Figure numerals: 10-desalinated water subsystem, 20-desalted water subsystem, 30-mixing device, 101-seawater pretreatment device, 102-seawater desalination device, 103-first fresh water pump, 104-first chlorine dosing device, 105-first sodium hydroxide dosing device, 201-deep seawater pretreatment device, 202-electrodialysis seawater desalination device, 203-second fresh water pump, 204-second chlorine dosing device, 205-second sodium hydroxide dosing device. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] The specific implementation of the concept of this application is described below.

[0020] Please refer to Figure 1 The embodiment of the present invention provides a seawater desalination post-treatment system for producing highly mineralized drinking water, the system comprising:

[0021] Desalination subsystem 10, desalination subsystem 20 and mixing device 30; desalination subsystem 10 is used to convert seawater into fresh water, and desalination subsystem 20 is used to convert deep seawater containing minerals and rare elements into desalination water; the inlet of mixing device 30 is connected to the outlet of desalination subsystem 10 and desalination subsystem 20 respectively, and mixing device 30 is used to mix fresh water and desalination water to obtain highly mineralized drinking water;

[0022] The desalinated water subsystem 10 includes a seawater pretreatment device 101, a seawater desalination device 102, a first freshwater pump 103, a first chlorine dosing device 104, and a first sodium hydroxide dosing device 105 connected in sequence; the desalted water subsystem 20 includes a deep seawater pretreatment device 201, an electrodialysis seawater desalination device 202, a second freshwater pump 203, a second chlorine dosing device 204, and a second sodium hydroxide dosing device 205 connected in sequence.

[0023] In the embodiment of the present invention, since the deep seawater treated by the desalination subsystem contains minerals and rare elements, the properly treated desalted water also contains minerals and rare elements. In this way, after the fresh water produced by the desalination subsystem is mixed with the desalted water, highly mineralized drinking water containing minerals and rare elements can be obtained. Obviously, the seawater desalination post-treatment system provided by the present invention uses seawater as a water source, does not require acidification treatment, and can also adjust the water hardness. At the same time, it simplifies the post-processing steps of desalinated water, thereby reducing costs and improving efficiency.

[0024] It should be noted that deep seawater is seawater at a depth of 200 meters below sea level, which is rich in minerals and rare elements. Mixing devices include but are not limited to product water mixing tanks.

[0025] In a preferred embodiment, the seawater pretreatment device includes a seawater intake pump, a coagulation sedimentation tank or a flotation tank, a medium filter and a safety filter.

[0026] In the embodiment of the present invention, the specific combination of the seawater pretreatment device is determined according to the quality of the raw water and the requirements of the water inlet of the seawater desalination device.

[0027] In a preferred embodiment, the seawater desalination device is one of a multi-effect distillation seawater desalination device, a multi-stage flash evaporation seawater desalination device or a reverse osmosis seawater desalination device.

[0028] In a preferred embodiment, the deep seawater pretreatment device includes a water intake pump, a medium filter and a safety filter.

[0029] In a preferred embodiment, the electrodialysis cation membrane used in the electrodialysis seawater desalination device is a monovalent cation selective permeable membrane for seawater concentration and salt production, and the anion membrane is an ion exchange membrane.

[0030] In a more preferred embodiment, in the electrodialysis seawater desalination device, all anions in the deep seawater can pass through the anionic membrane, and monovalent cations can pass through the cationic membrane.

[0031] In a preferred embodiment, the desalinated water produced by the electrodialysis seawater desalination device contains the same multivalent cations as deep seawater.

[0032] In a preferred embodiment, seawater enters the seawater pretreatment device through the inlet of the seawater pretreatment device, the outlet of the seawater pretreatment device is connected to the inlet of the seawater desalination device, the outlet of the seawater desalination device is connected to the inlet of the first fresh water pump, the outlet of the first fresh water pump is connected to the inlet of the mixing device, and the first chlorine dosing device and the first sodium hydroxide dosing device are sequentially provided on the pipeline between the first fresh water pump and the mixing device;

[0033] The deep seawater enters the deep seawater pretreatment device through the inlet of the deep seawater pretreatment device, the outlet of the deep seawater pretreatment device is connected to the inlet of the electrodialysis seawater desalination device, the outlet of the electrodialysis seawater desalination device is connected to the inlet of the second fresh water pump, the outlet of the second fresh water pump is connected to the inlet of the mixing device, and the second chlorine dosing device and the second sodium hydroxide dosing device are sequentially arranged on the pipeline between the second fresh water pump and the mixing device.

[0034] The present invention also provides a seawater desalination post-treatment method for producing highly mineralized drinking water based on the above system, comprising:

[0035] S1: Determine the seawater pretreatment device and seawater desalination device based on the seawater quality detected;

[0036] S2: Determine the deep seawater pretreatment device and electrodialysis desalination device based on the water quality of the deep seawater detected;

[0037] S3: Determine the dosage of chlorine dioxide of the first chlorine dosing device and the dosage of sodium hydroxide of the first sodium hydroxide dosing device based on the desalinated water generated by the seawater desalination device;

[0038] S4: determining a dosage of chlorine dioxide of the second chlorine dosing device and a dosage of sodium hydroxide of the second sodium hydroxide dosing device based on the desalted water generated by the electrodialysis seawater desalination device;

[0039] S5: Determine the ratio of fresh water to desalted water based on the target salinity of the highly mineralized drinking water, the detected salinity of the fresh water produced by the desalination water subsystem, and the salinity of the desalted water produced by the desalination water subsystem to obtain highly mineralized drinking water.

[0040] In a more preferred embodiment, step S3 determines the chlorine dioxide dosage of the first chlorine dosing device and the sodium hydroxide dosage of the first sodium hydroxide dosing device based on the desalinated water produced by the seawater desalination device, comprising:

[0041] Determine at least one chlorination point and the amount of chlorine dioxide added at each chlorination point, and at least one residual chlorine test point based on the detected initial flow rate of the desalinated water and the total organic matter / bacterial count contained therein; wherein the chlorination point and the residual chlorine test point are spaced apart;

[0042] Collect the residual chlorine amount at each residual chlorine test point, and determine whether the terminal residual chlorine amount of the terminal residual chlorine test point does not exceed the preset residual chlorine threshold within a preset time period;

[0043] If the judgment result is yes, the desalinated water produced by the first chlorine dosing device flows into the first sodium hydroxide dosing device through the outlet; otherwise, the process returns to adjust the chlorine dioxide dosage of each chlorination point until the judgment result is yes;

[0044] According to the detected pH value of the desalinated water produced by the first chlorine dosing device, the amount of sodium hydroxide added by the first sodium hydroxide dosing device is determined to obtain fresh water with a target pH value.

[0045] It should be noted that a residual chlorine test point is correspondingly set after each chlorination point; and for at least two chlorination points, the residual chlorine test point is located between adjacent chlorination points. More specifically, for example, chlorination point 1-residual chlorine test point 1-chlorination point 2-residual chlorine test point 2 are sequentially set between the pipelines of the first fresh water pump and the first sodium hydroxide dosing device.

[0046] More specifically, the initial dosage C at the initial chlorination point cl,0 (mg / L) is determined by the following formula:

[0047]

[0048] Where TOC is the total organic carbon of desalinated water (mg / L); N0 is the total number of initial colonies (CFU / mL); N t is the target colony count (CFU / mL) to meet the sterilization requirements; Y is the effective chlorine utilization rate; k is the disinfection rate constant L / (mg·min); t is the unit time (min);

[0049] The real-time acceleration rate v of the i-th chlorination point Cl,i (g / h) is determined by the following formula:

[0050]

[0051] Among them, C target is the preset residual chlorine threshold (mg / L); C measured,i-1 is the measured residual chlorine value of the i-1 residual chlorine test point (mg / L); F is the initial flow rate of desalinated water (m 3 / h); η is the pipeline attenuation coefficient, <1; α is the safety factor (0.05-0.1, to prevent sudden load increase); ρ is the effective chlorine coefficient, dimensionless; it should be noted that when the added chlorine is ClO2, ρ = 1; when the added chlorine is NaClO, ρ = the density of NaClO solution (g / L) / the effective chlorine content in the NaClO solution (g / L);

[0052] If the residual chlorine at the terminal residual chlorine test point exceeds the standard (i.e. the judgment result is no), the dosage of each chlorination point is reduced proportionally; if the residual chlorine at the terminal residual chlorine test point is insufficient, the dosage of the initial chlorination point is increased first to ensure initial sterilization.

[0053] It should be noted that, similarly, the chlorine dioxide dosage of the second chlorine dosing device and the sodium hydroxide dosage of the second sodium hydroxide dosing device are also determined by the above method, which will not be repeated here.

[0054] In the embodiment of the application, the real-time adding rate of the chlorination point is dynamically adjusted through the flow and residual chlorine feedback, so that the sterilization requirement can be met and the residual chlorine can be controlled, and the chlorination control in the water treatment process is improved.

[0055] In a more preferred embodiment, step S5 determines the ratio of fresh water and desalinated water, comprising:

[0056] According to the target salt content of the high-mineralized drinking water, the detected salt content of the fresh water generated by the fresh water subsystem, and the detected salt content of the desalinated water generated by the desalinated water subsystem, an initial ratio of fresh water and desalinated water is determined; the initial ratio is determined by the following formula:

[0057]

[0058] Wherein, R0 is the initial ratio of fresh water and desalinated water; C 脱盐水 is the salt content of the desalinated water; C 目标 is the target salt content; C 淡水 is the salt content of the fresh water;

[0059] The fresh water and the desalinated water are mixed in the mixing device according to the initial ratio to obtain initial drinking water; and a first salt content of the initial drinking water is detected in real time;

[0060] A difference between the target salt content and the first salt content is calculated, and the initial ratio is dynamically adjusted according to the difference until the difference does not exceed a preset error threshold, to determine a current ratio; the current ratio is determined by the following formula:

[0061]

[0062] e t1 =C 目标 -C1

[0063] Wherein, R 实际 is the current ratio; K p , K i , K d are proportional gain, integral gain, and differential gain, respectively; e t1 is the difference between the target salt content C 目标 and the first salt content C1; t is the current time;

[0064] The current mineral content of the drinking water in the current mixing device is detected;

[0065] According to the current mineral content and the target mineral content, a mineral compensation amount is determined; the mineral compensation amount is determined by the following formula:

[0066]

[0067] Among them, Q 补 is the mineral compensation amount (L / h); F 总 is the flow rate (m 3 / h); M 目标 is the target mineral content (mg / L); M 当前 is the current mineral content (mg / L); C 矿化剂 is the concentration of active ingredient of mineralizer (g / L);

[0068] After compensating the minerals in the mixing device according to the mineral compensation amount, detecting a second salt content C2 of the drinking water in the mixing device;

[0069] Determine the final ratio of fresh water and desalinated water based on the current mineral content, target mineral content, second salinity, and target salinity:

[0070]

[0071] e t2 =C 目标 -(M 目标 -M 当前 )-C2

[0072] Among them, R 最终 is the final ratio; K p , K i , K d are proportional gain, integral gain, and differential gain respectively; C2 is the second salinity; and t is the current time.

[0073] It should be noted that the salt content can be obtained by using an online conductivity meter or a TDS analyzer. The units of the salt content and mineral content involved in step S5 are both mg / L.

[0074] In this invention, salt content is first controlled by PID mixing through staged control, and then a mineralizer is added to further compensate for the mineral content, ensuring the health and taste of highly mineralized drinking water. Because mineral compensation further affects the salt content of the drinking water, the final salt content of the drinking water needs to be dynamically adjusted. Ultimately, salt control and mineral replenishment are decoupled to ensure stable system operation.

[0075] In order to more clearly illustrate the technical solutions and advantages of the present invention, an application method of a seawater desalination post-treatment system for producing highly mineralized drinking water is described in detail below through several embodiments.

[0076] In the following examples, a product water mixing tank is used as the mixing device.

[0077] Example 1

[0078] 1) The raw seawater (salt content of 33000 mg / L) is passed into the seawater pretreatment device 101 for raw seawater pretreatment (including raw seawater water intake, coagulation sedimentation / air flotation, medium filtration and security filtration steps);

[0079] 2) The pretreated raw seawater in step 1 is passed into the seawater desalination device 102 for seawater desalination process, and the desalinated water (salt content less than 50 mg / L) is passed into the product water mixing pool 30 by the first fresh water pump 103. The desalinated water transportation pipeline from the first fresh water pump to the product water mixing pool has the first chlorine dosing device 104 (adding 1.5 mg / L ClO2 to the desalinated water) and the first sodium hydroxide dosing device 105 (adding 98% mass concentration of NaOH);

[0080] 3) The deep seawater (salt content of 35000 mg / L) is passed into the deep seawater pretreatment device 201 for deep seawater pretreatment (including water intake, medium filtration and security filtration steps);

[0081] 4) The pretreated deep seawater in step 3 is passed into the electrodialysis seawater desalination device 202 for electrodialysis seawater desalination process, and the desalted water (in which, the concentration of Na + is 10 mg / L, the concentration of K + is 2 mg / L, the concentration of Ca 2+ is 212 mg / L, the concentration of Mg 2+ is 1100 mg / L, the concentration of Cl - is 2940 mg / L, the concentration of SO4 2- is 4013 mg / L, the concentration of PO4 3- is 0.185 mg / L, the concentration of TDS (total dissolved solids) is 8356 mg / L, and the total hardness is 5056 mg / L) is passed into the product water mixing pool 30 by the second fresh water pump 203. The electrodialysis desalted water transportation pipeline from the second fresh water pump to the product water mixing pool has the second chlorine dosing device 204 (adding 1.5 mg / L ClO2 to the desalted water) and the second sodium hydroxide dosing device 205 (adding 98% mass concentration of NaOH);

[0082] 5) The desalted water produced in step 2 and the desalted water produced in step 4 are passed into the product water mixing pool 30 according to a ratio of 10:1 to output high salinity drinking water.

[0083] Example 2

[0084] 1) The raw seawater (salt content of 33000 mg / L) is passed into the seawater pretreatment device 101 for raw seawater pretreatment (including raw seawater water intake, medium filtration and security filtration steps);

[0085] 2) The raw seawater pretreated in step 1 is passed into a seawater desalination device 102 for desalination. The resulting desalinated water (salinity of 100 mg / L) is passed into a product water mixing tank 30 via a first fresh water pump 103. The desalinated water transport pipeline from the first fresh water pump to the product water mixing tank includes a first chlorine dosing device 104 (for adding 1.5 mg / L NaClO to the desalinated water) and a first sodium hydroxide dosing device 105 (for adding 98% mass concentration of NaOH).

[0086] 3) Passing deep seawater (salt content 35,000 mg / L) into the deep seawater pretreatment device 201 for deep seawater pretreatment (including water intake, medium filtration, and security filtration steps);

[0087] 4) The deep seawater pretreated in step 3 is passed into the electrodialysis desalination device 202 to perform the electrodialysis desalination process, and the desalted water (wherein Na + The concentration is 138mg / L, K + The concentration is 10 mg / L, Ca 2+ The concentration is 312mg / L, Mg 2+ The concentration is 1300 mg / L, Cl - The concentration is 3140mg / L, SO4 2- The concentration is 3913mg / L, PO4 3- The desalted water (with a concentration of 0.185 mg / L, a TDS (total dissolved solids) concentration of 9428 mg / L, and a total hardness of 5891 mg / L) is introduced into the product water mixing tank 30 via a second fresh water pump 203. A second chlorine dosing device 204 (for adding 1.5 mg / L NaClO to the desalted water) and a second sodium hydroxide dosing device 205 (for adding 98% mass concentration of NaOH) are provided in the electrodialysis desalted water transport pipeline from the second fresh water pump to the product water mixing tank.

[0088] 5) The fresh water produced in step 2 and the desalted water produced in step 4 are introduced into the product water mixing tank 30 in a ratio of 12:1 to output highly mineralized drinking water.

[0089] Example 3

[0090] 1) Raw seawater (salt content 33000 mg / L) is passed into the seawater pretreatment device 101 for raw seawater pretreatment (including raw seawater intake, medium filtration, and safety filtration steps);

[0091] 2) The raw seawater pretreated in step 1 is passed into a seawater desalination device 102 for desalination. The resulting desalinated water (salinity 80 mg / L) is passed into a product water mixing tank 30 via a first fresh water pump 103. The desalinated water transport pipeline from the first fresh water pump to the product water mixing tank includes a first chlorine dosing device 104 (for adding 1.5 mg / L NaClO to the desalinated water) and a first sodium hydroxide dosing device 105 (for adding 98% mass concentration of NaOH).

[0092] 3) Passing deep seawater (salt content 35,000 mg / L) into the deep seawater pretreatment device 201 for deep seawater pretreatment (including water intake, medium filtration, and security filtration steps);

[0093] 4) The deep seawater pretreated in step 3 is passed into the electrodialysis desalination device 202 to perform the electrodialysis desalination process, and the desalted water (wherein Na + The concentration of K is 183 mg / L. + The concentration of Ca is 12 mg / L, 2+ The concentration is 309mg / L, Mg 2+ The concentration is 1311 mg / L, Cl - The concentration is 3231mg / L, SO4 2- The concentration is 4013mg / L, PO4 3- The desalted water (with a concentration of 0.185 mg / L, a TDS (total dissolved solids) concentration of 9981 mg / L, and a total hardness of 6619 mg / L) is introduced into the product water mixing tank 30 via a second fresh water pump 203. A second chlorine dosing device 204 (for adding 1.5 mg / L NaClO to the desalted water) and a second sodium hydroxide dosing device 205 (for adding 98% mass concentration of NaOH) are provided in the electrodialysis desalted water transport pipeline from the second fresh water pump to the product water mixing tank.

[0094] 5) The fresh water produced in step 2 and the desalted water produced in step 4 are introduced into the product water mixing tank 30 in a ratio of 12:1 to output highly mineralized drinking water.

[0095] It should be understood that the structure illustrated in the embodiments of the present invention does not constitute a specific limitation on a seawater desalination post-processing system for producing highly mineralized drinking water. In other embodiments of the present invention, a seawater desalination post-processing system for producing highly mineralized drinking water may include more or fewer components than illustrated, or may combine or separate certain components, or employ a different component arrangement. The illustrated components may be implemented in hardware, software, or a combination of both.

[0096] The information interaction, execution process, etc. between the various devices in the above-mentioned system are based on the same concept as the embodiment of the method of the present invention. For specific contents, please refer to the description in the embodiment of the method of the present invention and will not be repeated here.

[0097] It should be noted that, in this article, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply the existence of any such actual relationship or order between these entities or operations. Moreover, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprising a ..." do not exclude the presence of other identical factors in the process, method, article or device comprising the elements.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A seawater desalination post-treatment system for producing highly mineralized drinking water, characterized in that: include: A desalinated water subsystem, a desalinated water subsystem, and a mixing device; the desalinated water subsystem is used to convert seawater into fresh water, and the desalinated water subsystem is used to convert deep seawater containing minerals and rare elements into desalinated water; the inlet of the mixing device is connected to the outlets of the desalinated water subsystem and the desalinated water subsystem respectively, and the mixing device is used to mix the fresh water and desalinated water to obtain highly mineralized drinking water; The desalinated water subsystem includes a seawater pretreatment device, a seawater desalination device, a first freshwater pump, a first chlorine dosing device, and a first sodium hydroxide dosing device connected in sequence; the desalted water subsystem includes a deep seawater pretreatment device, an electrodialysis seawater desalination device, a second freshwater pump, a second chlorine dosing device, and a second sodium hydroxide dosing device connected in sequence.

2. The system according to claim 1, wherein: The seawater pretreatment device comprises a seawater intake pump, a coagulation sedimentation tank or an air flotation tank, a medium filter and a safety filter.

3. The system according to claim 1, wherein: The seawater desalination device is one of a multi-effect distillation seawater desalination device, a multi-stage flash evaporation seawater desalination device or a reverse osmosis seawater desalination device.

4. The system according to claim 1, wherein: The deep seawater pretreatment device includes a water intake pump, a medium filter and a safety filter.

5. The system according to claim 1, wherein: The electrodialysis cation membrane used in the electrodialysis seawater desalination device is a monovalent cation selective permeation membrane for seawater concentration and salt production, and the anion membrane is an ion exchange membrane.

6. The system according to claim 5, characterized in that In the electrodialysis seawater desalination device, all anions in the deep seawater can pass through the anion membrane, and monovalent cations can pass through the cation membrane.

7. The system according to claim 5, characterized in that The desalted water produced by the electrodialysis seawater desalination device contains the same multivalent cations as the deep seawater.

8. The system according to any one of claims 1 to 7, characterized in that: Seawater enters the seawater pretreatment device through the inlet of the seawater pretreatment device, the outlet of the seawater pretreatment device is connected to the inlet of the seawater desalination device, the outlet of the seawater desalination device is connected to the inlet of the first fresh water pump, the outlet of the first fresh water pump is connected to the inlet of the mixing device, and the first chlorine dosing device and the first sodium hydroxide dosing device are sequentially provided on the pipeline between the first fresh water pump and the mixing device; The deep seawater enters the deep seawater pretreatment device through the inlet of the deep seawater pretreatment device, the outlet of the deep seawater pretreatment device is connected to the inlet of the electrodialysis seawater desalination device, the outlet of the electrodialysis seawater desalination device is connected to the inlet of the second fresh water pump, the outlet of the second fresh water pump is connected to the inlet of the mixing device, and the second chlorine dosing device and the second sodium hydroxide dosing device are sequentially arranged on the pipeline between the second fresh water pump and the mixing device.

9. A seawater desalination post-treatment method for producing highly mineralized drinking water based on the system according to any one of claims 1 to 8, characterized in that: include: Determine the seawater pretreatment device and seawater desalination device based on the seawater quality detected; Determining a deep seawater pretreatment device and an electrodialysis seawater desalination device based on the water quality of the deep seawater detected; Determining the dosage of chlorine dioxide of the first chlorine dosing device and the dosage of sodium hydroxide of the first sodium hydroxide dosing device based on the desalinated water generated by the seawater desalination device; Determining the dosage of chlorine dioxide of the second chlorine dosing device and the dosage of sodium hydroxide of the second sodium hydroxide dosing device based on the desalted water generated by the electrodialysis seawater desalination device; The ratio of the fresh water to the desalted water is determined based on the target salinity of the highly mineralized drinking water, the detected salinity of the fresh water produced by the desalination water subsystem, and the salinity of the desalted water produced by the desalination water subsystem to obtain the highly mineralized drinking water.

10. The method according to claim 9, characterized in that The method of determining the chlorine dioxide dosage of the first chlorine dosing device and the sodium hydroxide dosage of the first sodium hydroxide dosing device based on the desalinated water generated by the seawater desalination device includes: Determining at least one chlorination point and the amount of chlorine dioxide added at each chlorination point, and at least one residual chlorine testing point based on the detected initial flow rate and the total amount of organic matter / bacterial count of the desalinated water; wherein the chlorination point and the residual chlorine testing point are spaced apart; Collect the residual chlorine amount at each residual chlorine test point, and determine whether the terminal residual chlorine amount of the terminal residual chlorine test point does not exceed the preset residual chlorine threshold within a preset time period; If the judgment result is yes, the desalinated water produced by the first chlorine dosing device flows into the first sodium hydroxide dosing device through the outlet; otherwise, the process returns to adjust the chlorine dioxide dosage of each chlorination point until the judgment result is yes; Determining the amount of sodium hydroxide added by the first sodium hydroxide dosing device based on the detected pH value of the desalinated water produced by the first chlorine dosing device to obtain the desalinated water with a target pH value; and / or, Determining the ratio of the fresh water to the desalted water comprises: determining an initial ratio of the fresh water to the desalted water according to a target salinity of the highly mineralized drinking water, the detected salinity of the fresh water produced by the desalination water subsystem, and the salinity of the desalted water produced by the desalination water subsystem; mixing the fresh water and the desalted water in a mixing device according to the initial ratio to obtain initial drinking water; and detecting a first salt content of the initial drinking water in real time; calculating a difference between the target salt content and the first salt content, and dynamically adjusting the initial ratio according to the difference until the difference does not exceed a preset error threshold, thereby determining a current ratio; detecting the current mineral content of the drinking water currently in the mixing device; determining a mineral compensation amount according to the current mineral content and the target mineral content; After compensating the minerals in the mixing device according to the mineral compensation amount, detecting a second salt content of the drinking water in the mixing device; A final ratio of the fresh water to the desalted water is determined according to the current mineral content, the target mineral content, the second salinity, and the target salinity.

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