Novel dynamic reverse osmosis and nanofiltration ultra-high concentration system and method thereof

Abstract

The invention provides a novel dynamic reverse osmosis and nanofiltration ultrahigh concentration system and a method thereof. The novel dynamic reverse osmosis and nanofiltration ultrahigh concentration system comprises a first pump, a reverse osmosis system, a first three-way valve, a second three-way valve, a third three-way valve, a piston assembly, a nanofiltration system, a first circulating pump and a second circulating pump. A plurality of circulation loops are formed through cooperation of the structures, the brine concentration can be increased to 250 g / L or above under the working condition that the operation pressure does not exceed 70 bar, meanwhile, the data are monitored through an electrical and automatic control system, information such as the operation pressure, the flushing flow and the flushing time are optimized and fed back, real-time adjustment is conducted, and the brine concentration can be increased to be larger than 250 g / L. The energy consumption and the cost of high-salinity wastewater treatment are remarkably reduced, the membrane pollution condition is relieved, and the method has an important application prospect.

Description

Technical Field

[0001] The present invention relates to the field of wastewater treatment, and in particular to a novel dynamic reverse osmosis and nanofiltration ultra-high concentration system and a wastewater treatment method. Background Art

[0002] The development of sewage treatment technology shows a trend of green, intelligent and energy-saving. In 2022, the national industrial and urban domestic wastewater discharge problem is 43.95 billion cubic meters, of which industrial wastewater discharge is 20.72 billion cubic meters. With the continuous improvement of domestic environmental protection requirements and the improvement of corporate emission standards, more and more companies are beginning to change from emission reduction to emission limitation and then to zero emission. The zero-discharge process of high-salt wastewater is mainly divided into pretreatment, membrane deep treatment and evaporation crystallization. The main difficulty in the industry at present is that the evaporation and crystallization process has extremely high energy consumption, which makes it very expensive to achieve complete zero sewage discharge. Therefore, it is necessary to greatly improve the concentration rate of membrane deep treatment through process improvement and upgrading, thereby reducing the later evaporation cost. Summary of the invention

[0003] In order to solve the problem of low wastewater concentration rate, the present disclosure provides a novel dynamic reverse osmosis and nanofiltration ultra-high concentration system and method thereof to increase the concentration of brine under low operating pressure.

[0004] In the first aspect, the present disclosure provides a novel dynamic reverse osmosis and nanofiltration ultra-high concentration system, comprising a first pump, a reverse osmosis system, a first three-way valve, a second three-way valve, a third three-way valve, a piston assembly, a nanofiltration system, a first circulation pump and a second circulation pump, wherein the output port of the first pump is connected to the reverse osmosis system, the first output port of the reverse osmosis system is connected to the outside, the second output port of the reverse osmosis system is connected to the first opening of the first three-way valve, the second opening of the first three-way valve is connected to the first piston assembly opening of the piston assembly, the third opening of the first three-way valve is connected to the second piston assembly opening of the piston assembly, the third piston assembly opening of the piston assembly is connected to the fourth opening of the second three-way valve, the fifth opening of the second three-way valve is connected to the second nanofiltration opening of the nanofiltration system, the sixth opening of the second three-way valve is connected to the inlet of the second circulation pump, and the The outlet of the first circulation pump is communicated with the first piston assembly opening of the piston assembly through the first valve; the fourth piston assembly opening of the piston assembly is communicated with the seventh opening of the third three-way valve, the eighth opening of the third three-way valve is communicated with the first nanofiltration opening of the nanofiltration system, the ninth opening of the third three-way valve is communicated with the inlet of the first circulation pump, and the outlet of the second circulation pump is communicated with the second piston assembly opening of the piston assembly through the second valve, wherein a piston is provided in the piston assembly, the first piston assembly opening of the piston assembly and the third piston assembly opening of the piston assembly are located on one side of the piston, the second piston assembly opening of the piston assembly and the fourth piston assembly opening of the piston assembly are located on the other side of the piston, and the nanofiltration system is provided with a nanofiltration membrane, and the first nanofiltration opening and the second nanofiltration opening of the nanofiltration system are respectively located at both ends of the nanofiltration membrane.

[0005] Optionally, it includes a first state, when the concentration system is in the first state, the first pump supplies liquid to the reverse osmosis system, the liquid passes through the reverse osmosis system to produce purified liquid and a first saline solution, the first saline solution passes through the first opening and the second opening of the first three-way valve in sequence to reach the first piston assembly opening of the piston assembly, the first saline solution pushes the piston in the piston assembly to move toward the side of the second piston assembly opening, so that the second saline solution in the piston assembly leaves from the fourth piston assembly opening and passes through the seventh opening and the eighth opening of the third three-way valve in sequence to reach the first nanofiltration opening of the nanofiltration system; the second saline solution passes through the nanofiltration membrane from one side of the first nanofiltration opening; the second saline solution leaves from the second nanofiltration opening and passes through the fifth opening and the sixth opening of the second three-way valve in sequence to reach the second circulation pump, and is pumped to the piston assembly by the second circulation pump.

[0006] Optionally, it includes a second state. When in the second state, the first pump supplies liquid to the reverse osmosis system, and the liquid passes through the reverse osmosis system to produce purified liquid and a third saline solution. The third saline solution passes through the first opening and the third opening of the first three-way valve in sequence to reach the second piston assembly opening of the piston assembly. The third saline solution pushes the piston in the piston assembly to move toward the side of the first piston assembly opening, so that the fourth saline solution in the piston assembly leaves from the third piston assembly opening and passes through the fourth opening and the fifth opening of the second three-way valve in sequence to reach the second nanofiltration opening of the nanofiltration system, and the fourth saline solution passes through the nanofiltration membrane from one side of the second nanofiltration opening; the fourth saline solution leaves from the first nanofiltration opening and passes through the eighth opening and the ninth opening of the third three-way valve in sequence to reach the first circulation pump, and is pumped to the piston assembly by the first circulation pump.

[0007] Optionally, in the first state, the rate at which the second saline solution passes through the nanofiltration membrane is constant, and in the second state, the rate at which the fourth saline solution passes through the nanofiltration membrane is constant.

[0008] Optionally, it also includes a pumping device. When the concentrating system is in a first waste liquid discharge state, the second saline solution is sucked away from the opening of the fourth piston assembly by the pumping device and passes through the third three-way valve and the nanofiltration membrane of the nanofiltration system in sequence, and is finally transported to the outside through the pumping device; when the concentrating system is in a second waste liquid discharge state, the fourth saline solution is sucked away from the opening of the third piston assembly by the pumping device and passes through the second three-way valve and the nanofiltration membrane of the nanofiltration system in sequence, and is finally transported to the outside through the pumping device.

[0009] Optionally, it also includes a raw material tank, the inlet of which is connected to the first nanofiltration opening and the second nanofiltration opening of the nanofiltration system respectively, the outlet of which is connected to the first pump, and conductivity meters are respectively provided at the inlet and outlet of the raw material tank.

[0010] Optionally, when the concentration system is in a cleaning state, the liquid is transported from the raw material tank to the reverse osmosis system and the high-pressure nanofiltration system in sequence under the action of the first pump, and finally returns to the raw material tank.

[0011] Optionally, a sodium bed is provided between the raw material tank and the first pump, and the sodium bed is used to remove calcium ions and magnesium ions in the liquid.

[0012] In a second aspect, the present disclosure provides a wastewater treatment method, which treats wastewater using the concentration system in any embodiment of the first aspect.

[0013] Optionally, the concentrating system includes a first state, a second state, a first waste liquid discharge state, a second waste liquid discharge state and a cleaning state, and the concentrating system changes in the order of the first state, the first waste liquid discharge state, the cleaning state, the second state, the second waste liquid discharge state and the cleaning state.

[0014] Through the coordination of the above structures, one or more circulation loops are formed, thereby increasing the brine concentration to a higher level under low operating pressure. At the same time, the above data are monitored by the electrical and automatic control system, and the feedback of operating pressure, flushing flow, flushing time and other information are optimized and adjusted in real time, which significantly reduces the energy consumption and cost of high-salt wastewater treatment and alleviates membrane pollution. It has important application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of a novel dynamic reverse osmosis and nanofiltration ultra-high concentration system in a certain embodiment of the present disclosure.

[0016] Figure 2 for Figure 1 Schematic diagram of the structure of the new dynamic reverse osmosis and nanofiltration ultra-high concentration system in the injection state.

[0017] Figure 3 for Figure 1 Schematic diagram of the structure of the new dynamic reverse osmosis and nanofiltration ultra-high concentration system in the first state.

[0018] Figure 4 for Figure 1 Schematic diagram of the structure of the new dynamic reverse osmosis and nanofiltration ultra-high concentration system in the first waste liquid discharge state.

[0019] Figure 5 for Figure 1 Schematic diagram of the structure of the new dynamic reverse osmosis and nanofiltration ultra-high concentration system in the first cleaning state.

[0020] Figure 6 for Figure 1 Schematic diagram of the structure of the new dynamic reverse osmosis and nanofiltration ultra-high concentration system in the second state.

[0021] Figure 7 for Figure 1 Schematic diagram of the structure of the new dynamic reverse osmosis and nanofiltration ultra-high concentration system in the second waste liquid discharge state.

[0022] Figure 8 for Figure 1 Schematic diagram of the structure of the new dynamic reverse osmosis and nanofiltration ultra-high concentration system in the second cleaning state.

[0023] Symbols in the figure: 100, first pump; 200, reverse osmosis system; 210, first output port; 220, second output port; 310, first three-way valve; 311, first opening; 312, second opening; 313, third opening; 320, second three-way valve; 321, fourth opening; 322, fifth opening; 323, sixth opening; 330, third three-way valve; 331, seventh opening; 332, eighth opening; 333, ninth opening 400, piston assembly; 410, first piston assembly opening; 420, second piston assembly opening; 430, third piston assembly opening Component opening; 440, fourth piston component opening; 450, piston; 500, nanofiltration system; 510, first nanofiltration opening; 520, second nanofiltration opening; 530, third nanofiltration opening; 600, first circulation pump; 700, second circulation pump; 810, pumping device; 820, raw material tank; 830, sodium bed; 840, concentrated liquid tank; 910, conductivity meter; 920, flow meter; 930, thermometer; 940, pressure gauge; 950, hardness tester; 960, first valve; 970, second valve; 980, first branch; 990, second branch. DETAILED DESCRIPTION

[0024] It should be understood that the exemplary embodiments described herein should be considered only for descriptive purposes and not for limiting purposes. Descriptions of features or aspects in each exemplary embodiment should generally be considered applicable to similar features or aspects in other exemplary embodiments.

[0025] It should be noted that reverse osmosis is a widely used technology for deep sewage treatment. However, the maximum concentration of brine is limited by the transmembrane pressure difference on both sides of the membrane. If the traditional reverse osmosis process is used, the operating pressure will far exceed the maximum tolerable pressure of the traditional reverse osmosis membrane element. Therefore, the new dynamic reverse osmosis and nanofiltration ultra-high concentration system proposed in the present disclosure can increase the brine concentration to more than 250g / L (i.e., ultra-high concentration of wastewater) under the condition of an operating pressure not exceeding 70bar, significantly reducing the energy consumption and cost of high-salt wastewater treatment, and has important application prospects.

[0026] Specifically, the present disclosure provides a novel dynamic reverse osmosis and nanofiltration ultra-high concentration system, such as Figure 1As shown, it includes a first pump 100 , a reverse osmosis system 200 , a first three-way valve 310 , a second three-way valve 320 , a third three-way valve 330 , a piston assembly 400 , a nanofiltration system 500 , a first circulation pump 600 , and a second circulation pump 700 . The output port of the first pump 100 is in communication with the reverse osmosis system 200, the first output port 210 of the reverse osmosis system 200 is in communication with the outside, the second output port 220 of the reverse osmosis system 200 is in communication with the first opening 311 of the first three-way valve 310, the second opening 312 of the first three-way valve 310 is in communication with the first piston assembly opening 410 of the piston assembly 400, the third opening 313 of the first three-way valve 310 is in communication with the second piston assembly opening 420 of the piston assembly 400, the third piston assembly opening 430 of the piston assembly 400 is in communication with the fourth opening 321 of the second three-way valve 320, the fifth opening 322 of the second three-way valve 320 is in communication with the second nanofiltration opening 520 of the nanofiltration system 500, the sixth opening 323 of the second three-way valve 320 is in communication with the inlet of the second circulation pump 700, and the outlet of the second circulation pump 700 is in communication with the second piston assembly opening 420 of the piston assembly 400 through the second valve 970; the piston assembly 40 0 is communicated with the seventh opening 331 of the third three-way valve 330, the eighth opening 332 of the third three-way valve 330 is communicated with the first nanofiltration opening 510 of the nanofiltration system 500, the ninth opening 333 of the third three-way valve 330 is communicated with the inlet of the first circulation pump 600, and the outlet of the first circulation pump 600 is communicated with the first piston assembly opening 410 of the piston assembly 400 through the first valve 960, wherein a piston 450 is provided in the piston assembly 400, the first piston assembly opening 410 of the piston assembly 400 and the third piston assembly opening 430 of the piston assembly 400 are located on one side of the piston 450, the second piston assembly opening 420 of the piston assembly 400 and the fourth piston assembly opening 440 of the piston assembly 400 are located on the other side of the piston 450, and the nanofiltration system 500 is provided with a nanofiltration membrane, and the first nanofiltration opening 510 and the second nanofiltration opening 520 of the nanofiltration system 500 are respectively located at both ends of the nanofiltration membrane.

[0027] It should be noted that the reverse osmosis system 200 includes a reverse osmosis membrane, which intercepts salts, minerals and harmful substances in the liquid to purify the water body to obtain a purified liquid, while the difficult-to-purify parts are discharged to form a salt solution. Specifically, the reverse osmosis membrane includes but is not limited to a seawater reverse osmosis desalination membrane element, such as SW-8040 seawater desalination membrane.

[0028] The nanofiltration system 500 is provided with a nanofiltration membrane, and the solvent in the solution is separated through the nanofiltration membrane by using pressure, mainly targeting monovalent salts (such as sodium ions) in the liquid of the nanofiltration system 500. The nanofiltration membrane can be a high-pressure nanofiltration membrane element, such as NF-8040 nanofiltration membrane.

[0029] The first saline solution, the second saline solution, the third saline solution and the fourth saline solution are all saline solutions, that is, solutions containing salt (a compound composed of metal ions (including ammonium ions) and acid radical ions).

[0030] More specifically, the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system further includes a raw material tank 820 and a pumping device 810. The raw material tank 820 is connected to the input port of the first pump 100, so the liquid can be transported from the raw material tank 820 to the reverse osmosis system 200 through the first pump 100. The pumping device 810 is respectively connected to the first nanofiltration opening 510 and the second nanofiltration opening 520 of the nanofiltration system 500 through a pipeline. The liquid in the nanofiltration system 500 can be transported to the concentrated liquid tank 840 through the pumping device 810 under the suction of the pumping device 810 for storage.

[0031] It should be noted that, in some optional embodiments, the raw material tank 820 is connected to the first nanofiltration opening 510 and the second nanofiltration opening 520 of the nanofiltration system 500 through pipelines, and the liquid passing through the nanofiltration system 500 can be transported to the raw material tank 820 through the pipelines.

[0032] In some optional embodiments, the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system includes a liquid injection state, such as Figure 2 As shown, in the liquid injection state, the liquid is transported from the raw material tank 820 to the reverse osmosis system 200 under the action of the first pump 100. The reverse osmosis system 200 processes the liquid to obtain a purified liquid and a second saline solution, and the second saline solution sequentially passes through the first opening 311 and the third opening 313 of the first three-way valve 310 to reach the second piston assembly opening 420 of the piston assembly 400, and the second saline solution pushes the piston 450 in the piston assembly 400 to move toward one side of the first piston assembly opening 410, so that the second saline solution fills the entire piston assembly 400.

[0033] It should be noted that the second circulation pump is turned off and the second valve 970 at the outlet of the second circulation pump is tightly closed at this time.

[0034] In some optional embodiments, the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system includes a first state. When the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system is in the first state, the first pump 100 supplies liquid to the reverse osmosis system 200, and the liquid passes through the reverse osmosis system 200 to produce purified liquid and a first salt solution. The first salt solution sequentially passes through the first opening 311 and the second opening 312 of the first three-way valve 310 to reach the first piston assembly opening 410 of the piston assembly 400. The first salt solution pushes the piston 450 in the piston assembly 400 to move toward one side of the second piston assembly opening 420, so that the piston assembly The second saline in 400 leaves from the fourth piston assembly opening 440 and passes through the seventh opening 331 and the eighth opening 332 of the third three-way valve 330 in sequence to reach the first nanofiltration opening 510 of the nanofiltration system 500; the second saline passes through the nanofiltration membrane from one side of the first nanofiltration opening 510; the second saline leaves from the second nanofiltration opening 520 and passes through the fifth opening 322 and the sixth opening 323 of the second three-way valve 320 in sequence to reach the second circulation pump 700, and is pumped to the second piston assembly opening 420 of the piston assembly 400 by the second circulation pump 700 to be transported into the piston assembly 400, as shown in detail. Figure 3 At this time, the valve at the outlet of the second circulation pump is in an open state.

[0035] It should be noted that, optionally, the nanofiltration system 500 further includes a third nanofiltration opening 530, and the liquid (second saline solution) in the nanofiltration system 500 can be transported to the inlet of the sodium bed 830 through the third nanofiltration opening and re-enter the circulation. It should be noted that the sodium bed 830 is arranged between the raw material tank 820 and the first pump 100, and the liquid in the raw material tank 820 enters the sodium bed 830 through the inlet of the sodium bed 830 to remove calcium ions and magnesium ions in the liquid, and the treated liquid is transported to the first pump 100 through the outlet of the sodium bed 830.

[0036] In the above scheme, two sets of circulation loops can actually be formed in the first state. The first set of circulation loops is from the piston assembly 400 to the nanofiltration system 500, then to the second circulating pump 700, and finally back to the piston assembly 400. In the first set of circulation loops, since the saline solution will continuously go from the piston assembly 400 to the nanofiltration system 500 and then return to the piston assembly 400, it is ensured that the saline concentration difference on both sides of the nanofiltration membrane in the nanofiltration system 500 will not be too large, and then it is no longer necessary to provide a higher pressure to the nanofiltration system 500. Specifically, if the saline concentration difference on both sides of the nanofiltration membrane is too large, the working pressure of the required pump will increase when the water production is constant, and the nanofiltration membrane (the membrane material itself has a pressure limit in its structure) cannot withstand such a large pressure and is damaged and ruptured. The second set of circulation loops is from the sodium bed 830, the first pump 100, the reverse osmosis system 200, the piston assembly 400, and the nanofiltration system 500 to finally return to the sodium bed 830. In this system, liquid can be continuously circulated therein, reducing the pressure difference on both sides of the reverse osmosis membrane in the reverse osmosis system 200. At the same time, the arrangement of the piston assembly 400 can effectively convert the pressure provided by the first pump 100 into the power for the movement of the piston, thereby reducing the operating pressure of the entire system to a certain extent.

[0037] In some optional embodiments, the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system further includes a pumping device 810. When the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system is in the first waste liquid discharge state, the second saline solution is sucked out of the fourth piston assembly opening 440 by the pumping device 810 and sequentially passes through the seventh opening 331 and the eighth opening 332 of the third three-way valve 330 and the nanofiltration membrane of the nanofiltration system 500, and is finally transported to the outside through the pumping device 810, for example, it can be finally transported to the concentrated liquid tank 840 for storage, as shown in the following example. Figure 4 At this time, the first valve 960 and the second valve 970 should be in a closed state.

[0038] When the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system is in the second waste liquid discharge state, the fourth salt solution is sucked out from the third piston assembly opening 430 by the pumping device 810 and sequentially passes through the fourth opening 321 and the fifth opening 322 of the second three-way valve 320 and the nanofiltration membrane of the nanofiltration system 500, and is finally transported to the outside through the pumping device 810, such as finally being transported to the concentrated liquid tank 840 for storage, as shown in FIG. Figure 7 At this time, the first valve 960 and the second valve 970 should be in a closed state.

[0039] Specifically, the liquid extraction device 810 is connected to the first nanofiltration opening 510 and the second nanofiltration opening 520 of the nanofiltration system 500 through the first branch 980 and the second branch 990, respectively, and valves are provided in the first branch 980 and the second branch 990. Under normal circumstances, the valves of the first branch 980 and the second branch 990 are normally closed. However, in the first waste liquid discharge state, the valve of the first branch 980 is closed, and the valve of the second branch 990 is opened, such as Figure 4 The second saline solution leaves the fourth piston assembly opening 440 and passes through the seventh opening 331 and the eighth opening 332 of the third three-way valve 330 to reach the first nanofiltration opening 510 of the nanofiltration system 500, passes through the nanofiltration membrane of the nanofiltration system 500 to reach the second nanofiltration opening 520, and is then transported to the concentrate tank 840 through the second branch 990.

[0040] In the second waste liquid discharge state, the valve of the first branch 980 is opened and the valve of the second branch 990 is closed. Figure 7 At this time, the fourth salt solution leaves the third piston assembly opening 430 and passes through the fourth opening 321 and the fifth opening 322 of the second three-way valve 320 to reach the second nanofiltration opening 520 of the nanofiltration system 500, and passes through the nanofiltration membrane to reach the first nanofiltration opening 510, and is finally transported to the concentrated liquid tank 840 through the pumping device 810.

[0041] Optionally, the inlet of the raw material tank 820 is connected to the first nanofiltration opening 510 and the second nanofiltration opening 520 of the nanofiltration system 500 respectively, the outlet of the raw material tank 820 is connected to the first pump 100, and the inlet and outlet of the raw material tank 820 are respectively provided with conductivity meters 910.

[0042] Optionally, when the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system is in a cleaning state, the liquid is transported from the raw material tank 820 to the reverse osmosis system 200 and the high-pressure nanofiltration system 500 in sequence under the action of the first pump 100, and finally returns to the raw material tank 820.

[0043] More specifically, the cleaning state is divided into a first cleaning state and a second cleaning state. In the first cleaning state, the liquid is transported from the raw material tank 820 to the reverse osmosis system 200 under the action of the first pump 100, and then transported to the second piston assembly opening 420 of the piston assembly 400 through the first three-way valve 310, and then sequentially passes through the fourth piston assembly opening 440, the third three-way valve 330, the first nanofiltration opening 510 of the nanofiltration system 500, the nanofiltration membrane and the second nanofiltration opening 520, and finally returns to the raw material tank 820. For details, please refer to Figure 5 At this time, when the water flows through the reverse osmosis system 200, purified liquid can also be produced.

[0044] In the second cleaning state, the liquid is transported from the raw material tank 820 to the reverse osmosis system 200 under the action of the first pump 100, and then transported to the first piston assembly opening 410 of the piston assembly 400 through the first three-way valve 310, and then sequentially passes through the third piston assembly opening 430, the second three-way valve 320, the second nanofiltration opening 520 of the nanofiltration system 500, the nanofiltration membrane and the first nanofiltration opening 510, and finally returns to the raw material tank 820. For details, please refer to Figure 8 At this time, when the water flows through the reverse osmosis system 200, purified liquid can also be produced.

[0045] In some optional embodiments, the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system includes a second state, such as Figure 6 As shown, when in the second state, the first pump 100 supplies liquid to the reverse osmosis system 200, and the liquid passes through the reverse osmosis system 200 to produce purified liquid and a third saline solution, and the third saline solution sequentially passes through the first opening 311 and the third opening 313 of the first three-way valve 310 to reach the second piston assembly opening 420 of the piston assembly 400, and the third saline solution pushes the piston 450 in the piston assembly 400 to move toward one side of the first piston assembly opening 410, so that the fourth saline solution in the piston assembly 400 leaves from the third piston assembly opening 430 and sequentially passes through the fourth opening 321 and the fifth opening 322 of the second three-way valve 320 to reach the second nanofiltration opening 520 of the nanofiltration system 500, and the fourth saline solution passes through the nanofiltration membrane from one side of the second nanofiltration opening 520; the fourth saline solution leaves from the first nanofiltration opening 510 and sequentially passes through the eighth opening 332 and the ninth opening 333 of the third three-way valve 330 to reach the first circulation pump 600, and is pumped to the piston assembly 400 by the first circulation pump 600.

[0046] Optionally, the liquid (fourth salt solution) in the nanofiltration system 500 can be transported to the inlet of the sodium bed 830 through the third nanofiltration opening 530 and re-enter the circulation.

[0047] In the above scheme, two sets of circulation loops can actually be formed in the second state. The first set of circulation loops is from the piston assembly 400 to the nanofiltration system 500, and then to the second circulating pump 600, and finally returns to the piston assembly 400. In the first set of circulation loops, since the saline solution can continuously go from the piston assembly 400 to the nanofiltration system 500 and then return to the piston assembly 400, it is ensured that the saline concentration difference on both sides of the nanofiltration membrane in the nanofiltration system 500 will not be too large, and then it is no longer necessary to provide a higher pressure to the nanofiltration system 500. The second set of circulation loops is then from the sodium bed 830, the first pump 100, the reverse osmosis system 200, the piston assembly 400, and the nanofiltration system 500 finally return to the sodium bed 830.

[0048] In the first state, the second salt solution passes through the nanofiltration membrane at a constant rate, and in the second state, the fourth salt solution passes through the nanofiltration membrane at a constant rate. The influence of concentration polarization on the membrane surface is reduced by stabilizing the speed at which the salt solution passes through the nanofiltration membrane.

[0049] At the same time, if Figure 1 As shown, optionally, a conductivity meter 910 and a flow meter 920 may be provided at the first output port 210 of the reverse osmosis system 200. A conductivity meter 910, a flow meter 920 and a thermometer 930 may also be provided between the outlet of the raw material tank 820 and the sodium bed 830 to monitor the conductivity, flow rate and temperature of the liquid flowing out of the raw material tank 820. A hardness detector 950 may be provided between the sodium bed 830 and the first pump 100 to monitor the hardness of the liquid coming out of the sodium bed 830. A pressure gauge 940 may be provided at the second output port 220 of the reverse osmosis system 200 to monitor the pressure of the liquid flowing out of the second output port 220 of the reverse osmosis system 200. A conductivity meter 910 and a flow meter 920 may be provided in the pipeline connecting the third nanofiltration opening 530 of the nanofiltration system 500 and the sodium bed 830.

[0050] In addition, the present disclosure provides a wastewater treatment method, which treats wastewater through a new dynamic reverse osmosis and nanofiltration ultra-high concentration system. Wherein, the new dynamic reverse osmosis and nanofiltration ultra-high concentration system includes a first state, a second state, a first waste liquid discharge state, a second waste liquid discharge state and a cleaning state, and the new dynamic reverse osmosis and nanofiltration ultra-high concentration system changes in the order of the first state, the first waste liquid discharge state, the cleaning state, the second state, the second waste liquid discharge state and the cleaning state. More specifically, the new dynamic reverse osmosis and nanofiltration ultra-high concentration system includes a first state, a second state, a first waste liquid discharge state, a second waste liquid discharge state, a first cleaning state and a second cleaning state, and the new dynamic reverse osmosis and nanofiltration ultra-high concentration system changes in the order of the first state, the first waste liquid discharge state, the first cleaning state, the second state, the second waste liquid discharge state and the second cleaning state.

[0051] In the first state, in order to ensure that the rate of the second salt solution passing through the nanofiltration membrane in the nanofiltration system 500 is constant, the power of the first pump 100 is continuously increased to ensure that the output pressure is sufficient. When the power of the first pump 100 reaches a specified power (usually the maximum power), the first state ends and the first pump 100 is turned off. Enter the first waste liquid discharge state.

[0052] In addition, in addition to ending the first state when the first pump 100 reaches a specified power, the first state can also be ended when the system recovery rate reaches a specified recovery rate. The recovery rate is calculated by combining the flow data measured by the flow meter 920 on the side of the reverse osmosis system 200 that produces the purified liquid with the total volume of the nanofiltration system and the circulation loop.

[0053] In the first waste liquid discharge state, after the pumping device 810 pumps all the salt solution in the nanofiltration system and the piston assembly 400 into the concentrated liquid tank 840, it is switched to the first cleaning state. It should be noted that at this time, the first pump 100 is closed, the first three-way valve 310 and the second three-way valve 320 are closed. For details, see Figure 4 .

[0054] In the first cleaning state, the conductivity of the salt solution in the pipeline can be detected because the conductivity meter 910 is provided in the pipeline from the nanofiltration system 500 to the raw material tank 820. Specifically, a pipeline is provided between the second nanofiltration opening of the nanofiltration system 500 and the raw material tank 820, and the conductivity meter 910 is provided on the pipeline.

[0055] When the conductivity value of the cleaning liquid recorded on the conductivity meter 910 changes greatly, it proves that there is still concentrated liquid remaining in the pipeline. Continue to increase the cleaning flow rate or increase the cleaning time until the conductivity value stabilizes, indicating that the concentrated liquid in the pipeline is completely cleaned. At this time, the first cleaning state ends and enters the second state.

[0056] In the second state, in order to ensure that the rate at which the fourth saline solution in the nanofiltration system 500 passes through the nanofiltration membrane is constant, the power of the first pump 100 is continuously increased to ensure that the output pressure is sufficient. When the power of the first pump 100 reaches the specified specified power, the first state ends and the first pump 100 is turned off. Enter the second waste liquid discharge state. Of course, in some embodiments, the first state can also be ended when the recovery rate reaches the preset value, and the first pump 100 is turned off. It should be noted that in some embodiments, the fourth saline solution at this time can be understood as the saline solution on one side of the third piston assembly opening 430 remaining in the piston assembly 400 after the first cleaning state ends.

[0057] In the second waste liquid discharge state, after the pumping device 810 pumps all the salt solution in the nanofiltration system and the piston assembly 400 out to the concentrated liquid tank 840, it switches to the second cleaning state. It should be noted that at this time, the first pump 100 is closed, the first three-way valve 310 and the third three-way valve 330 are closed. For details, see Figure 7 .

[0058] In the second cleaning state, the conductivity of the salt solution in the pipeline can be detected because the conductivity meter 910 is provided in the pipeline from the nanofiltration system 500 to the raw material tank 820. Specifically, a pipeline is provided between the first nanofiltration opening of the nanofiltration system 500 and the raw material tank 820, and the conductivity meter 910 is provided on the pipeline. When the conductivity value of the cleaning liquid recorded on the conductivity meter 910 changes greatly, it proves that there is still concentrated liquid remaining in the pipeline, and the cleaning flow rate or cleaning time is continued to be increased until the conductivity value is stable, indicating that the concentrated liquid in the pipeline is completely cleaned, and the second cleaning state ends at this time.

[0059] In addition, various high-precision measuring sensors (such as conductivity meter 910, flow meter 920, thermometer 930, etc.) are deployed on the new dynamic reverse osmosis and nanofiltration ultra-high concentration system to measure and collect data such as flow, pressure, conductivity, temperature, etc. of the influent and produced water at each stage. The above data are monitored through the electrical and automatic control system to optimize the feedback of operating pressure, flushing flow, flushing time and other information and make real-time adjustments.

[0060] The water production flow in the high-pressure nanofiltration system can be monitored by the flow meter 920. As the nanofiltration system continues to work, the brine concentration in the pipeline becomes higher and higher. To ensure a constant water production, the operating pressure needs to be gradually increased. After the electrical and automatic control system detects a decrease in water production in the nanofiltration system through the flow meter 920, it will automatically increase the power of the first pump 100 in a timely manner, optimize the feedback operating pressure, and make real-time adjustments to ensure a constant water production of the nanofiltration system.

[0061] Specifically, the operating pressure can be controlled by formula (1), which means that when the square of the difference between the real-time measured water production flow rate and the system set water production flow rate is the smallest, the operating pressure is the optimal operating pressure.

[0062]

[0063] Among them, P in (t) represents the operating pressure of the high-pressure pump, the unit is MPa; Q P,0 Respectively represent the real-time measured water flow rate and the specified water flow rate, and its unit is m 3 / h.Q P,0 , the specified water production flow rate is the preset value.

[0064] A conductivity meter 910 is also deployed to monitor the ion conductivity of the cleaning liquid in real time. When the conductivity value of the cleaning liquid recorded on the conductivity meter 910 changes greatly, it proves that there is still concentrated liquid remaining in the pipeline. Continue to increase the cleaning flow rate or increase the cleaning time until the conductivity value is stable, indicating that the concentrated liquid in the pipeline is completely cleaned, and the cleaning is completed at this time.

[0065] The cleaning time can be controlled by formula (2), which means that the cleaning is completed when the change of the conductivity of the concentrated solution outlet measured in real time within a certain interval is less than the set tolerance.

[0066]

[0067] Among them, σ b (t+Δt),σ b(t) represents the conductivity of the outlet solution at time t+Δt and time t in the cleaning stage, respectively, and its unit is S / m; ε represents the setting tolerance; Δt represents the time interval between adjacent data transmitted by the sensor, and its unit is s.

[0068] In addition, an appropriate amount of high-efficiency descaling agent (including but not limited to PTP-0100) can be added to the raw material tank 820 to increase the concentration limit of each ion in the water sample.

[0069] A descaling agent (including but not limited to PTP-0100) may be added to the sodium bed 830 to remove calcium, magnesium, silicon, aluminum, and other ions.

[0070] The operating pressure of the first pump 100 is a variable dynamic operating pressure.

[0071] The ultra-high concentration technology developed by the patent of this invention can increase the concentration of brine to more than 250g / L (with NaCl as solute) under the condition of operating pressure not exceeding 70bar, while the traditional reverse osmosis technology can only concentrate to about 80g / L at most. This technology can significantly reduce the energy consumption and cost of high-salt wastewater treatment and has important application prospects. We analyzed the operating parameters and economic benefits of this patented technology compared with traditional reverse osmosis technology (as shown in Table 1). Assuming that the feed flow rate is 20m3 / h and the total dissolved solids of the feed liquid are 36g / L (with NaCl as solute), the total amount of concentrated water sent to the evaporation process is expected to be reduced by more than 80% (from 9.0m3 / h to 2.8m3 / h) by using the new ultra-high concentration technology in this patent, and the total power consumption cost of the evaporation process is 6.05 million yuan / year (calculated based on 300 days of operation per year), which is more than 80% lower than the use of traditional reverse osmosis technology (saving more than 13.39 million yuan). This technology is mainly aimed at the zero wastewater discharge process, which further concentrates the high-concentration brine before it is sent to the evaporation device without affecting the factory's original conventional reverse osmosis concentration process.

[0072]

[0073]

[0074] Taking high-concentration salt water (NaCl) as an example, under typical operating pressure (70 bar), the concentration of the concentrate (i.e. the liquid placed in the concentrate tank 840) can only reach 82 g / L. The new dynamic reverse osmosis and nanofiltration ultra-high concentration system proposed in this patent can increase the salt water concentration to more than 250 g / L under the operating pressure of no more than 70 bar.

[0075] Compared with the traditional continuous feed reverse osmosis process, the dynamic reverse osmosis proposed in this patent includes a flushing process in each cycle, which can effectively alleviate membrane fouling. Determining the optimal flushing time is crucial to the normal operation of the system. First, a short flushing time leads to incomplete cleaning of the pipeline. At the same time, as the system circulates, the concentration of brine treated by the nanofiltration system becomes higher and higher, which will not only cause water scaling to block the pipeline and membrane channel, but also increase the operating pressure and further increase the energy consumption of the system. Secondly, the concentration of brine entering the nanofiltration system is low in the early stage of system operation. At this time, the working pressure of the pump and the compressive strength of the nanofiltration membrane meet the current required water production flow rate. When the flushing time is too short, the concentration of brine will continue to increase in the later stage. Under the condition of ensuring the same water production flow rate or recovery rate, the operating pressure will exceed the normal working pressure of the pump and the upper limit of the compressive strength of the nanofiltration membrane, affecting the normal operation of the entire system. On the contrary, although increasing the flushing time can alleviate the membrane fouling phenomenon, it will also increase the operation cycle of the concentration system, resulting in a decrease in the efficiency of the entire process. Therefore, the optimization of the flushing time is also a prominent innovation of this process.

[0076] The new dynamic reverse osmosis and nanofiltration ultra-high concentration system proposed in this patent can increase the brine concentration to more than 250g / L under the condition of operating pressure not exceeding 70bar. At the same time, the entire process is divided into multiple stages according to the flow. The above data is monitored by the electrical and automatic control system, and the operating pressure, flushing flow rate, flushing time and other information are optimized and fed back and adjusted in real time, which significantly reduces the energy consumption and cost of high-salt wastewater treatment and alleviates membrane pollution. It has important application prospects.

[0077] Obviously, the above embodiments of the present disclosure are merely examples for clearly illustrating the present disclosure, and are not intended to limit the implementation methods of the present disclosure. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the claims of the present disclosure.

Claims

1. A novel dynamic reverse osmosis and nanofiltration ultra-high concentration system, characterized in that: The invention comprises a first pump (100), a reverse osmosis system (200), a first three-way valve (310), a second three-way valve (320), a third three-way valve (330), a piston assembly (400), a nanofiltration system (500), a first circulation pump (600) and a second circulation pump (700), wherein the output port of the first pump (100) is in communication with the reverse osmosis system (200), the first output port (210) of the reverse osmosis system (200) is in communication with the outside, the second output port (220) of the reverse osmosis system (200) is in communication with the first opening (311) of the first three-way valve (310), the second opening (312) of the first three-way valve (310) is in communication with the outside, and the second output port (220) of the reverse osmosis system (200) is in communication with the first opening (311) of the first three-way valve (310), and the second opening (312) of the first three-way valve (310) is in communication with the outside. The first piston assembly opening (410) of the piston assembly (400) is in communication with the first piston assembly opening (410), the third opening (313) of the first three-way valve (310) is in communication with the second piston assembly opening (420) of the piston assembly (400), the third piston assembly opening (430) of the piston assembly (400) is in communication with the fourth opening (321) of the second three-way valve (320), the fifth opening (322) of the second three-way valve (320) is in communication with the second nanofiltration opening (520) of the nanofiltration system (500), the sixth opening (323) of the second three-way valve (320) is in communication with the inlet of the second circulation pump (700), and the inlet of the second circulation pump (700) is in communication with the inlet of the second circulation pump (700). The outlet is communicated with the second piston assembly opening (420) of the piston assembly (400) through the second valve (970); the fourth piston assembly opening (440) of the piston assembly (400) is communicated with the seventh opening (331) of the third three-way valve (330); the eighth opening (332) of the third three-way valve (330) is communicated with the first nanofiltration opening (510) of the nanofiltration system (500); the ninth opening (333) of the third three-way valve (330) is communicated with the inlet of the first circulation pump (600); the outlet of the first circulation pump (600) is communicated with the first piston assembly opening (510) of the piston assembly (400) through the first valve (960). 410), wherein a piston (450) is provided in the piston assembly (400), a first piston assembly opening (410) of the piston assembly (400) and a third piston assembly opening (430) of the piston assembly (400) are located on one side of the piston (450), a second piston assembly opening (420) of the piston assembly (400) and a fourth piston assembly opening (440) of the piston assembly (400) are located on the other side of the piston (450), and the nanofiltration system (500) is provided with a nanofiltration membrane, and the first nanofiltration opening (510) and the second nanofiltration opening (520) of the nanofiltration system (500) are respectively located at two ends of the nanofiltration membrane.

2. The concentration system according to claim 1, characterized in that: The invention comprises a first state, wherein when the concentration system is in the first state, the first pump (100) supplies liquid to the reverse osmosis system (200), the liquid passes through the reverse osmosis system (200) to produce purified liquid and a first saline solution, the first saline solution sequentially passes through the first opening (311) and the second opening (312) of the first three-way valve (310) to reach the first piston assembly opening (410) of the piston assembly (400), the first saline solution pushes the piston (450) in the piston assembly (400) to move toward the side of the second piston assembly opening (420), so that the second saline solution in the piston assembly (400) is The liquid leaves the fourth piston assembly opening (440) and passes through the seventh opening (331) and the eighth opening (332) of the third three-way valve (330) in sequence to reach the first nanofiltration opening (510) of the nanofiltration system (500); the second saline solution passes through the nanofiltration membrane from one side of the first nanofiltration opening (510); the second saline solution leaves the second nanofiltration opening (520) and passes through the fifth opening (322) and the sixth opening (323) of the second three-way valve (320) in sequence to reach the second circulation pump (700), and is pumped to the piston assembly (400) by the second circulation pump (700).

3. The concentration system according to claim 2, characterized in that: The invention comprises a second state, when in the second state, the first pump (100) supplies liquid to the reverse osmosis system (200), the liquid passes through the reverse osmosis system (200) to produce purified liquid and a third saline solution, the third saline solution passes through the first opening (311) and the third opening (313) of the first three-way valve (310) in sequence to reach the second piston assembly opening (420) of the piston assembly (400), the third saline solution pushes the piston (450) in the piston assembly (400) to move toward one side of the first piston assembly opening (410), so that the fourth saline solution in the piston assembly (400) is discharged from the first piston assembly (420). The fourth saline leaves the third piston assembly opening (430) and passes through the fourth opening (321) and the fifth opening (322) of the second three-way valve (320) in sequence to reach the second nanofiltration opening (520) of the nanofiltration system (500), and the fourth saline passes through the nanofiltration membrane from one side of the second nanofiltration opening (520); the fourth saline leaves the first nanofiltration opening (510) and passes through the eighth opening (332) and the ninth opening (333) of the third three-way valve (330) in sequence to reach the first circulation pump (600), and is pumped to the piston assembly (400) by the first circulation pump (600).

4. The concentration system according to claim 3, characterized in that: In the first state, the rate at which the second saline solution passes through the nanofiltration membrane is constant, and in the second state, the rate at which the fourth saline solution passes through the nanofiltration membrane is constant.

5. The concentration system according to claim 3, characterized in that: It also includes a pumping device (810). When the concentration system is in the first waste liquid discharge state, the second saline solution is sucked out of the fourth piston assembly opening (440) by the pumping device (810) and sequentially passes through the third three-way valve (330) and the nanofiltration membrane of the nanofiltration system (500), and is finally transported to the outside through the pumping device (810); When the concentration system is in the second waste liquid discharge state, the fourth saline solution is sucked out of the third piston assembly opening (430) by the pumping device (810) and sequentially passes through the second three-way valve (320) and the nanofiltration membrane of the nanofiltration system (500) and is finally transported to the outside through the pumping device (810).

6. The concentration system according to claim 1, characterized in that: The invention also comprises a raw material tank (820), wherein the inlet of the raw material tank (820) is respectively connected to the first nanofiltration opening (510) and the second nanofiltration opening (520) of the nanofiltration system (500), the outlet of the raw material tank (820) is connected to the first pump (100), and the inlet and outlet of the raw material tank (820) are respectively provided with a conductivity meter (910).

7. The concentration system according to claim 6, characterized in that: When the concentration system is in a cleaning state, the liquid is transported from the raw material tank (820) to the reverse osmosis system (200) and the high-pressure nanofiltration system (500) in sequence under the action of the first pump (100), and finally returns to the raw material tank (820).

8. The concentration system according to claim 1, characterized in that: A sodium bed (830) is provided between the raw material tank (820) and the first pump (100), and the sodium bed (830) is used to remove calcium ions and magnesium ions in the liquid.

9. A method for treating wastewater, characterized in that: The wastewater is treated by the concentration system according to any one of claims 1 to 8.

10. The wastewater treatment method according to claim 9, characterized in that: The concentration system includes a first state, a second state, a first waste liquid discharge state, a second waste liquid discharge state and a cleaning state. The concentration system changes in the order of the first state, the first waste liquid discharge state, the cleaning state, the second state, the second waste liquid discharge state and the cleaning state.

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