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

Abstract

The present application provides a novel dynamic reverse osmosis and nanofiltration ultra-high concentration system and a method thereof. The novel dynamic reverse osmosis and nanofiltration ultra-high 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 circulation pump and a second circulation pump. By means of the cooperation of said structures, a plurality of circulation loops is formed, such that, with an operating pressure not exceeding 70 bar, the brine concentration can be increased to more than 250 g / L. In addition, by monitoring the above data by using an electrical and automatic control system, the operating pressure, the flushing flow rate and the flushing time, etc. are optimized, fed back and adjusted in real time, thereby significantly reducing the energy consumption and cost of high-salinity wastewater treatment, and alleviating membrane fouling, which has important application prospects.

Description

Novel Dynamic Reverse Osmosis and Nanofiltration Ultra-High Concentration System and Method

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202411410879.7, filed on October 10, 2024, entitled “Novel Dynamic Reverse Osmosis and Nanofiltration Ultra-High Concentration System and Method Thereof,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of wastewater treatment, specifically to a novel dynamic reverse osmosis and nanofiltration ultra-high concentration system and a wastewater treatment method. Background Technology

[0004] Wastewater treatment technology is developing towards green, intelligent, and energy-saving trends. In 2022, the total discharge of industrial and urban domestic wastewater nationwide reached 43.95 billion cubic meters, of which industrial wastewater accounted for 20.72 billion cubic meters. With increasingly stringent domestic environmental protection requirements and stricter emission standards for enterprises, more and more companies are moving from emission reduction to emission limits and ultimately to zero discharge. Zero-discharge processes for high-salinity wastewater mainly consist of pretreatment, membrane-based advanced treatment, and evaporation crystallization. Currently, the main challenge in the industry lies in the extremely high energy consumption of the evaporation crystallization process, making the cost of achieving complete zero wastewater discharge very expensive. Therefore, it is necessary to improve and upgrade the process to significantly increase the concentration rate of membrane-based advanced treatment, thereby reducing the cost of subsequent evaporation. Summary of the Invention

[0005] To address the problem of low wastewater concentration, this disclosure provides a novel dynamic reverse osmosis and nanofiltration ultra-high concentration system and method to increase brine concentration under low operating pressure.

[0006] In one aspect, this 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. 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, and the third piston assembly opening of the piston assembly... The second three-way valve 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 circulating pump, and the outlet of the second circulating pump is connected to the second piston assembly opening of the piston assembly through the second valve; the fourth piston assembly opening of the piston assembly is connected to the seventh opening of the third three-way valve, the eighth opening of the third three-way valve is connected to the first nanofiltration opening of the nanofiltration system, the ninth opening of the third three-way valve is connected to the inlet of the first circulating pump, and the outlet of the first circulating pump is connected to the first piston assembly opening of the piston assembly through the first valve.

[0007] Optionally, the piston assembly includes a piston, with a first piston assembly opening and a third piston assembly opening located on one side of the piston, and a second piston assembly opening and a fourth piston assembly opening located on the other side of the piston.

[0008] Optionally, the nanofiltration system includes a nanofiltration membrane, with the first nanofiltration opening and the second nanofiltration opening located at opposite ends of the nanofiltration membrane.

[0009] Optionally, including 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 brine solution. The first brine solution sequentially passes through the first opening and the second opening of the first three-way valve to reach the first piston assembly opening of the piston assembly. The first brine solution pushes the piston in the piston assembly to move towards the side of the second piston assembly opening, so that the second brine solution in the piston assembly leaves from the fourth piston assembly opening and sequentially passes through the seventh opening and the eighth opening of the third three-way valve to reach the first nanofiltration opening of the nanofiltration system. The second brine solution passes through the nanofiltration membrane from one side of the first nanofiltration opening. The second brine solution leaves from the second nanofiltration opening and sequentially passes through the fifth opening and the sixth opening of the second three-way valve to reach the second circulation pump, which pumps it to the piston assembly.

[0010] Optionally, a second state is included. When the concentration system is in the second 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 third brine. The third brine passes sequentially through the first and third openings of the first three-way valve to the second piston assembly opening of the piston assembly. The third brine pushes the piston in the piston assembly to move towards one side of the first piston assembly opening, causing the fourth brine in the piston assembly to leave from the third piston assembly opening and sequentially pass through the fourth and fifth openings of the second three-way valve to the second nanofiltration opening of the nanofiltration system. The fourth brine passes through the nanofiltration membrane from one side of the second nanofiltration opening. The fourth brine leaves from the first nanofiltration opening and sequentially passes through the eighth and ninth openings of the third three-way valve to the first circulation pump, which pumps it to the piston assembly.

[0011] Optionally, when the concentration system is in the first state, the rate at which the second brine passes through the nanofiltration membrane is constant, and when the concentration system is in the second state, the rate at which the fourth brine passes through the nanofiltration membrane is constant.

[0012] Optionally, a liquid extraction device is also included. When the concentration system is in the first waste liquid discharge state, the second brine is drawn out from the opening of the fourth piston assembly by the liquid extraction device and sequentially passes through the third three-way valve and the nanofiltration membrane of the nanofiltration system, and is finally transported to the outside by the liquid extraction device. When the concentration system is in the second waste liquid discharge state, the fourth brine is drawn out from the opening of the third piston assembly by the liquid extraction device and sequentially passes through the second three-way valve and the nanofiltration membrane of the nanofiltration system, and is finally transported to the outside by the liquid extraction device.

[0013] 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, the outlet of which is connected to the first pump, and a conductivity meter is provided at the inlet and outlet of the raw material tank.

[0014] Optionally, when the concentration system is in the cleaning state, the liquid is sequentially transported from the raw material tank to the reverse osmosis system and the high-pressure nanofiltration system under the action of the first pump, and finally returned to the raw material tank.

[0015] Optionally, a sodium bed is provided between the raw material tank and the first pump, the sodium bed being used to remove calcium and magnesium ions from the liquid.

[0016] Optionally, the nanofiltration system further includes a third nanofiltration opening through which the liquid in the nanofiltration system can be delivered to the inlet of the sodium bed;

[0017] Optionally, when the concentration system is in the first state, the liquid flows sequentially through the sodium bed, the first pump, the reverse osmosis system, the piston assembly, and the nanofiltration system to return to the sodium bed;

[0018] Optionally, when the concentration system is in the second state, the liquid flows sequentially through the sodium bed, the first pump, the reverse osmosis system, the piston assembly, and the nanofiltration system to return to the sodium bed.

[0019] Optionally, the reverse osmosis system includes a reverse osmosis membrane for purifying the liquid to obtain the purified liquid.

[0020] Secondly, this disclosure provides a wastewater treatment method that treats wastewater through a concentration system in any embodiment of the first aspect.

[0021] Optionally, 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, and the concentration system changes sequentially 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.

[0022] Optionally, the cleaning states include a first cleaning state and a second cleaning state. A conductivity meter is installed in the pipeline connecting the nanofiltration system to the raw material tank to detect the conductivity of the brine solution in the pipeline. The concentration system sequentially changes according to the following order: first state, first waste liquid discharge state, first cleaning state, second state, second waste liquid discharge state, and second cleaning state. In the first cleaning state, when the change in conductivity is less than a set tolerance, the first cleaning state ends and the system enters the second state. In the second cleaning state, when the change in conductivity is less than the set tolerance, the second cleaning state ends.

[0023] The above structures work together to form one or more circulation loops, thereby increasing the brine concentration to a higher level under low operating pressure. At the same time, the electrical and automatic control system monitors the above data, optimizes and adjusts information such as operating pressure, flushing flow rate and flushing time in real time, significantly reducing the energy consumption and cost of high-salinity wastewater treatment and alleviating membrane fouling, which has important application prospects. Attached Figure Description

[0024] Figure 1 is a schematic diagram of the structure of a novel dynamic reverse osmosis and nanofiltration ultra-high concentration system in one embodiment of this disclosure.

[0025] Figure 2 is a schematic diagram of the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system in Figure 1 when it is in the liquid injection state.

[0026] Figure 3 is a schematic diagram of the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system in Figure 1 in its first state.

[0027] Figure 4 is a schematic diagram of the structure of the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system in Figure 1 when it is in the first waste liquid discharge state.

[0028] Figure 5 is a schematic diagram of the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system in Figure 1 when it is in the first cleaning state.

[0029] Figure 6 is a schematic diagram of the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system in Figure 1 in its second state.

[0030] Figure 7 is a schematic diagram of the structure of the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system in Figure 1 when it is in the second waste liquid discharge state.

[0031] Figure 8 is a schematic diagram of the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system in Figure 1 when it is in the second cleaning state.

[0032] In the diagram, the following are the markings: 100, First pump; 200, Reverse osmosis system; 210, First outlet; 220, Second outlet; 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. Component opening; 440, fourth piston assembly opening; 450, piston; 500, nanofiltration system; 510, first nanofiltration opening; 520, second nanofiltration opening; 530, third nanofiltration opening; 600, first circulating pump; 700, second circulating pump; 810, liquid extraction device; 820, raw material tank; 830, sodium bed; 840, concentrate 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 Implementation

[0033] It should be understood that the exemplary embodiments described herein should be considered descriptive only and not for limiting purposes. The description of features or aspects in each exemplary embodiment should generally be considered applicable to similar features or aspects in other exemplary embodiments.

[0034] It should be noted that reverse osmosis is a widely used advanced wastewater treatment technology; however, the maximum concentration of brine is limited by the transmembrane pressure difference across the membrane. If a traditional reverse osmosis process is used, the operating pressure will far exceed the maximum pressure that traditional reverse osmosis membrane elements can withstand. Therefore, the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system proposed in this disclosure can increase the brine concentration to over 250 g / L (i.e., ultra-high concentration of wastewater) under operating pressure not exceeding 70 bar, significantly reducing the energy consumption and cost of high-salinity wastewater treatment, and has significant application prospects.

[0035] In some embodiments, this disclosure provides a novel dynamic reverse osmosis and nanofiltration ultra-high concentration system, as shown in FIG1, including 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 connected to the reverse osmosis system 200. The first output port 210 of the reverse osmosis system 200 is connected to the outside. The second output port 220 of the reverse osmosis system 200 is connected to the first opening 311 of the first three-way valve 310. The second opening 312 of the first three-way valve 310 is connected to the first piston assembly opening 410 of the piston assembly 400. The third opening 313 of the first three-way valve 310 is connected to the second piston assembly opening 420 of the piston assembly 400. The third piston assembly opening 430 of the piston assembly 400 is connected to the fourth opening 321 of the second three-way valve 320. The fifth opening 322 of the second three-way valve 320 is connected to the second nanofiltration opening 520 of the nanofiltration system 500. The sixth opening 323 of the second three-way valve 320 is connected to the inlet of the second circulation pump 700. The outlet of the second circulation pump 700 is connected to the second piston assembly opening 420 of the piston assembly 400 through the second valve 970. The fourth piston assembly opening 440 of the 0 is connected to the seventh opening 331 of the third three-way valve 330, the eighth opening 332 of the third three-way valve 330 is connected to the first nanofiltration opening 510 of the nanofiltration system 500, the ninth opening 333 of the third three-way valve 330 is connected to the inlet of the first circulating pump 600, and the outlet of the first circulating pump 600 is connected to the first piston assembly opening 410 of the piston assembly 400 through the first valve 960. The piston assembly 400 is provided with a piston 450, the first piston assembly opening 410 and the third piston assembly opening 430 of the piston assembly 400 are located on one side of the piston 450, and the second piston assembly opening 420 and the fourth piston assembly opening 440 of the piston assembly 400 are located on the other side of the piston 450. 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.

[0036] It should be noted that the reverse osmosis system 200 includes a reverse osmosis membrane, which filters out salt, minerals, and harmful substances from the liquid to purify the water and obtain purified liquid, while the portion that is difficult to purify is discharged to form brine. In some embodiments, the reverse osmosis membrane includes, but is not limited to, seawater reverse osmosis desalination membrane elements, such as the SW-8040 desalination membrane.

[0037] The nanofiltration system 500 is equipped with a nanofiltration membrane, which uses pressure to separate the solvent in the solution. It is mainly used for 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 the NF-8040 nanofiltration membrane.

[0038] The first, second, third, and fourth salt solutions are all salt solutions, that is, solutions containing salts (compounds composed of metal ions (including ammonium ions) and acid radical ions).

[0039] In some embodiments, the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system further includes a feed tank 820 and a liquid extraction device 810. The feed tank 820 is connected to the inlet of the first pump 100, so liquid can be transported from the feed tank 820 to the reverse osmosis system 200 via the first pump 100. The liquid extraction device 810 is connected via pipelines to the first nanofiltration opening 510 and the second nanofiltration opening 520 of the nanofiltration system 500, respectively. Liquid in the nanofiltration system 500 can be transported to the concentrate tank 840 for storage by the suction of the liquid extraction device 810.

[0040] 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.

[0041] In some alternative embodiments, the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system includes a liquid injection state, as shown in Figure 2. In the liquid injection state, liquid is transported from the feed tank 820 to the reverse osmosis system 200 by the action of the first pump 100. The reverse osmosis system 200 processes the liquid to obtain purified liquid and a second brine solution. The second brine 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. The second brine solution pushes the piston 450 in the piston assembly 400 to move towards one side of the first piston assembly opening 410, so that the second brine solution fills the entire piston assembly 400.

[0042] It should be noted that the second circulation pump is shut down and the second valve 970 at the outlet of the second circulation pump is tightly closed at this time.

[0043] 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. The liquid passes through the reverse osmosis system 200 to produce purified liquid and a first brine solution. The first brine 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 brine solution pushes the piston 450 in the piston assembly 400 to move towards the side of the second piston assembly opening 420, causing the piston assembly 400 to... The second brine solution exits from the fourth piston assembly opening 440 and sequentially 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; the second brine solution passes through the nanofiltration membrane from one side of the first nanofiltration opening 510; the second brine solution exits from the second nanofiltration opening 520 and sequentially passes through the fifth opening 322 and the sixth opening 323 of the second three-way valve 320 to reach the second circulation pump 700, which pumps it to the second piston assembly opening 420 of the piston assembly 400 for delivery into the piston assembly 400, as shown in Figure 3. At this time, the valve at the outlet of the second circulation pump is in the open state.

[0044] It should be noted that, optionally, the nanofiltration system 500 also includes a third nanofiltration opening 530. The liquid (second brine) in the nanofiltration system 500 can be transported through the third nanofiltration opening to the inlet of the sodium bed 830 to re-enter the circulation system. It should also be noted that the sodium bed 830 is located between the raw material tank 820 and the first pump 100. The liquid from the raw material tank 820 enters the sodium bed 830 through the inlet to remove calcium and magnesium ions. The treated liquid is then transported to the first pump 100 through the outlet of the sodium bed 830.

[0045] In the above scheme, two circulation loops can actually be formed in the first state. The first circulation loop runs from piston assembly 400 to nanofiltration system 500, then to the second circulation pump 700, and finally back to piston assembly 400. In the first circulation loop, since the brine continuously flows from piston assembly 400 to nanofiltration system 500 and back to piston assembly 400, the brine concentration difference across the nanofiltration membrane in nanofiltration system 500 is not too large, thus eliminating the need to provide higher pressure to nanofiltration system 500. In some embodiments, if the brine concentration difference across the nanofiltration membrane is too large, the operating pressure of the pump required to maintain a constant permeate flow rate will increase, and the nanofiltration membrane (due to its inherent pressure limit) will not be able to withstand such pressure, leading to damage and rupture. The second circulation loop runs from sodium bed 830, first pump 100, reverse osmosis system 200, piston assembly 400, nanofiltration system 500, and finally back to sodium bed 830. In this system, the liquid can continuously circulate, reducing the pressure difference across the reverse osmosis membrane in reverse osmosis system 200. Meanwhile, the piston assembly 400 can effectively convert the pressure provided by the first pump 100 into the power for piston movement, thereby reducing the operating pressure of the entire system to a certain extent.

[0046] In some optional embodiments, the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system also includes a liquid extraction device 810. When the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system is in the first waste liquid discharge state, the second brine is drawn out from the fourth piston assembly opening 440 by the liquid extraction 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. Finally, it is transported to the outside through the liquid extraction device 810, for example, it can be finally transported to the concentrate tank 840 for storage, as shown in Figure 4. At this time, the first valve 960 and the second valve 970 should be in the closed state.

[0047] When the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system is in the second waste liquid discharge state, the fourth brine is drawn out from the third piston assembly opening 430 by the suction 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 suction device 810. It can then be stored in the concentrate tank 840, as shown in Figure 7. At this time, the first valve 960 and the second valve 970 should be in the closed state.

[0048] In some embodiments, 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, when the first waste liquid is discharged, the valve of the first branch 980 is closed and the valve of the second branch 990 is open, as shown in FIG4. The second brine leaves from the fourth piston assembly opening 440 and sequentially 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, and then 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.

[0049] When the second waste liquid is discharged, the valve of the first branch 980 is open and the valve of the second branch 990 is closed, as shown in Figure 7. At this time, the fourth brine leaves from the opening 430 of the third piston assembly and passes sequentially 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 then passes through the nanofiltration membrane to reach the first nanofiltration opening 510, and is finally transported to the concentrate tank 840 by the liquid pumping device 810.

[0050] 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, and the outlet of the raw material tank 820 is connected to the first pump 100. Conductivity meters 910 are respectively provided at the inlet and outlet of the raw material tank 820.

[0051] Optionally, when the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system is in the cleaning state, the liquid is sequentially transported from the feed tank 820 to the reverse osmosis system 200 and the high-pressure nanofiltration system 500 under the action of the first pump 100, and finally returned to the feed tank 820.

[0052] In some embodiments, 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 feed tank 820 to the reverse osmosis system 200 by the first pump 100, then through the first three-way valve 310 to the second piston assembly opening 420 of the piston assembly 400, and then sequentially 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, finally returning to the feed tank 820, as shown in Figure 5. At this time, purified liquid can also be produced when flowing through the reverse osmosis system 200.

[0053] In the second cleaning state, the liquid is transported from the feed tank 820 to the reverse osmosis system 200 by the first pump 100, then through the first three-way valve 310 to the first piston assembly opening 410 of the piston assembly 400, and then sequentially 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, finally returning to the feed tank 820. See Figure 8 for details. At this time, purified liquid is also produced when flowing through the reverse osmosis system 200.

[0054] In some alternative embodiments, the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system includes a second state, as shown in Figure 6. 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 brine solution. The third brine 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. The third brine solution pushes the piston 450 in the piston assembly 400 toward one side of the first piston assembly opening 410. The movement causes the fourth brine in the piston assembly 400 to leave from the third piston assembly opening 430 and sequentially pass 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. The fourth brine passes through the nanofiltration membrane from one side of the second nanofiltration opening 520. The fourth brine 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, which pumps it to the piston assembly 400.

[0055] Optionally, the liquid (fourth brine) in the nanofiltration system 500 can be transported through the third nanofiltration opening 530 to the inlet of the sodium bed 830 to re-enter the circulation.

[0056] In the above scheme, two circulation loops can actually be formed in the second state. The first circulation loop runs from piston assembly 400 to nanofiltration system 500, then to the second circulation pump 600, and finally back to piston assembly 400. In the first circulation loop, since the brine continuously flows from piston assembly 400 to nanofiltration system 500 and back to piston assembly 400, the concentration difference of the brine on both sides of the nanofiltration membrane in nanofiltration system 500 is not too large, thus eliminating the need to provide higher pressure to nanofiltration system 500. The second circulation loop runs from sodium bed 830, first pump 100, reverse osmosis system 200, piston assembly 400, nanofiltration system 500, and finally back to sodium bed 830.

[0057] In the first state, the rate at which the second brine passes through the nanofiltration membrane is constant; in the second state, the rate at which the fourth brine passes through the nanofiltration membrane is constant. Stabilizing the rate at which the brine passes through the nanofiltration membrane reduces the influence of concentration polarization at the membrane surface.

[0058] As shown in Figure 1, optionally, a conductivity meter 910 and a flow meter 920 can be installed at the first output port 210 of the reverse osmosis system 200. A conductivity meter 910, a flow meter 920, and a thermometer 930 can also be installed between the outlet of the feed tank 820 and the sodium bed 830 to monitor the conductivity, flow rate, and temperature of the liquid flowing out of the feed tank 820. A hardness meter 950 can be installed between the sodium bed 830 and the first pump 100 to monitor the hardness of the liquid exiting the sodium bed 830. A pressure gauge 940 can be installed 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 can be installed in the pipe connecting the third nanofiltration opening 530 of the nanofiltration system 500 to the sodium bed 830.

[0059] Furthermore, this disclosure provides a wastewater treatment method that treats wastewater using a novel dynamic reverse osmosis and nanofiltration ultra-high concentration system. The novel dynamic reverse osmosis and nanofiltration ultra-high concentration system includes a first state, a second state, a first wastewater discharge state, a second wastewater discharge state, and a cleaning state, wherein the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system sequentially changes through the first state, the first wastewater discharge state, the cleaning state, the second state, the second wastewater discharge state, and the cleaning state. In some embodiments, the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system includes a first state, a second state, a first wastewater discharge state, a second wastewater discharge state, a first cleaning state, and a second cleaning state, wherein the novel dynamic reverse osmosis and nanofiltration ultra-high concentration system sequentially changes through the first state, the first wastewater discharge state, the first cleaning state, the second state, the second wastewater discharge state, and the second cleaning state.

[0060] In the first state, to ensure a constant rate at which the second brine passes through the nanofiltration membrane in the nanofiltration system 500, the power of the first pump 100 is continuously increased to guarantee sufficient output pressure. 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 shut off. The system then enters the first waste liquid discharge state.

[0061] In addition to ending the first state when the first pump 100 reaches a specified power, the first state can also end 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 where the purified liquid is produced with the total volume of the nanofiltration system and the circulation loop.

[0062] In the first waste liquid discharge state, after the pumping device 810 has completely pumped the brine from the nanofiltration system and piston assembly 400 into the concentrate tank 840, it switches to the first cleaning state. It should be noted that at this time, the first pump 100 is closed, and the first three-way valve 310 and the second three-way valve 320 are closed, as shown in Figure 4.

[0063] During the first cleaning state, a conductivity meter 910 is installed in the pipeline from the nanofiltration system 500 to the raw material tank 820 to detect the conductivity of the brine in the pipeline. In some embodiments, a pipeline with a conductivity meter 910 is provided between the second nanofiltration opening of the nanofiltration system 500 and the raw material tank 820.

[0064] When the conductivity value of the cleaning fluid recorded on the conductivity meter 910 changes significantly, it indicates 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 has been completely cleaned. At this time, the first cleaning state ends and the second state begins.

[0065] In the second state, to ensure a constant rate of the fourth brine passing through the nanofiltration membrane in the nanofiltration system 500, the power of the first pump 100 is continuously increased to ensure sufficient output pressure. The first state ends when the power of the first pump 100 reaches a specified power, and the first pump 100 is shut off. The system then enters the second waste liquid discharge state. Of course, in some embodiments, the first state can also end and the first pump 100 shut off when the recovery rate reaches a preset value. It should be noted that in some embodiments, the fourth brine at this time can be understood as the brine remaining in the piston assembly 400 on the side of the third piston assembly opening 430 after the first cleaning state has ended.

[0066] In the second waste liquid discharge state, after the pumping device 810 has completely pumped the brine from the nanofiltration system and piston assembly 400 into the concentrate tank 840, it switches to the second cleaning state. It should be noted that at this time, the first pump 100 is closed, and the first three-way valve 310 and the third three-way valve 330 are closed, as shown in Figure 7.

[0067] During the second cleaning state, a conductivity meter 910 is installed in the pipeline from the nanofiltration system 500 to the raw material tank 820 to detect the conductivity of the brine in the pipeline. In some embodiments, a pipeline with a conductivity meter 910 is provided between the first nanofiltration opening of the nanofiltration system 500 and the raw material tank 820. When the conductivity value of the cleaning solution recorded on the conductivity meter 910 changes significantly, it indicates that there is still concentrated liquid remaining in the pipeline. The cleaning flow rate or cleaning time is increased until the conductivity value stabilizes, indicating that the concentrated liquid in the pipeline has been completely cleaned, at which point the second cleaning state ends.

[0068] In addition, the new dynamic reverse osmosis and nanofiltration ultra-high concentration system is equipped with various high-precision measurement and sensing devices (such as conductivity meter 910, flow meter 920, thermometer 930, etc.) to measure and collect data such as flow rate, pressure, conductivity, and temperature of the feed water and product water at each stage. The electrical and automatic control system monitors the above data, optimizes the feedback of operating pressure, flushing flow rate, and flushing time, and makes real-time adjustments.

[0069] Furthermore, the permeate flow rate in the high-pressure nanofiltration system can be monitored via flow meter 920. As the nanofiltration system continues to operate, the brine concentration in the pipeline increases, requiring a gradual increase in operating pressure to maintain a constant permeate flow. When the electrical and automatic control system detects a decrease in permeate flow through flow meter 920, it will automatically increase the power of the first pump 100, optimize the feedback operating pressure, and make real-time adjustments to ensure a constant permeate flow rate.

[0070] In some embodiments, the operating pressure can be controlled by formula (1), which means that when the square of the difference between the real-time measured water flow rate and the water flow rate set by the system is minimized, the operating pressure is the optimal operating pressure.

[0071] Among them, P in (t) represents the operating pressure of the high-pressure pump, and its unit is MPa; Q P,0 These represent the real-time measured permeate flow rate and the specified permeate flow rate, respectively, with units of m³. 3 / h. Q P,0 The specified water production flow rate is a preset value.

[0072] Furthermore, a conductivity meter 910 is deployed to monitor the ionic conductivity of the cleaning fluid in real time. When the conductivity value of the cleaning fluid recorded on the conductivity meter 910 changes significantly, it indicates that there is still concentrated liquid remaining in the pipeline. Continue to increase the cleaning flow rate or cleaning time until the conductivity value stabilizes, indicating that the concentrated liquid in the pipeline has been completely cleaned, at which point the cleaning is completed.

[0073] The cleaning time can be controlled by formula (2), which means that the cleaning ends when the change in the conductivity of the concentrate outlet measured in real time within a certain interval is less than the set tolerance.

[0074] Where, σ b (t+Δt), σ b (t) represents the conductivity of the outlet solution at time t+Δt and time t during the cleaning stage, respectively, with units of S / m; ε represents the set tolerance; Δt represents the time interval between adjacent data transmissions by the sensor, with units of s.

[0075] 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 limits of each ion in the water sample.

[0076] Descaling agents (including but not limited to PTP-0100) can be added to sodium bed 830 to remove ions such as calcium, magnesium, silicon, and aluminum.

[0077] The operating pressure of the first pump 100 is a variable dynamic operating pressure.

[0078] The ultra-high concentration technology disclosed herein can increase the brine concentration to over 250 g / L (using NaCl as solute) under operating pressure not exceeding 70 bar, while traditional reverse osmosis technology can only concentrate it to approximately 80 g / L at most. This technology can significantly reduce the energy consumption and cost of high-salinity wastewater treatment and has significant application prospects. We analyzed the operating parameters and economic benefits of this patented technology compared to traditional reverse osmosis technology (as shown in Table 1). Assuming a feed flow rate of 20 m³ / h and a total dissolved solids in the feed liquid of 36 g / L (using NaCl as solute), using the novel ultra-high concentration technology in this patent, the total amount of concentrate fed into the evaporation process is expected to be reduced by more than 80% (from 9.0 m³ / h to 2.8 m³ / h), and the total electricity 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 that of traditional reverse osmosis technology (saving more than 13.39 million yuan). This technology is primarily designed for zero-discharge wastewater processes, further concentrating high-concentration brine before it enters the evaporation unit without affecting the plant's existing conventional reverse osmosis concentration process.

[0079] Taking high-concentration brine (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 novel dynamic reverse osmosis and nanofiltration ultra-high concentration system proposed in this patent can increase the brine concentration to over 250 g / L under operating pressure not exceeding 70 bar.

[0080] Compared to traditional continuous-feed reverse osmosis processes, 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 for the normal operation of the system. First, too short a flushing time leads to incomplete cleaning of the pipelines. Simultaneously, as the system circulates, the concentration of brine treated by the nanofiltration system increases, eventually causing scaling and clogging of the pipelines and membrane channels, increasing operating pressure, and further increasing system energy consumption. Second, in the early stages of system operation, the brine concentration entering the nanofiltration system is low, at which point the pump's operating pressure and the nanofiltration membrane's compressive strength meet the current required permeate flow rate. However, if the flushing time is too short, the brine concentration will continue to rise in the later stages. Under the condition of maintaining the same permeate flow rate or recovery rate, the operating pressure will exceed the normal operating pressure of the pump and the upper limit of the nanofiltration membrane's compressive strength, affecting the normal operation of the entire system. Conversely, increasing the flushing time, while alleviating membrane fouling, also increases the operating cycle of the concentration system, leading to a decrease in overall process efficiency. Therefore, optimizing the flushing time is a key innovation of this process.

[0081] The novel dynamic reverse osmosis and nanofiltration ultra-high concentration system proposed in this patent can increase the brine concentration to over 250 g / L under operating pressure not exceeding 70 bar. At the same time, the entire process is divided into multiple stages according to the flow. The above data is monitored by an electrical and automatic control system, which optimizes and adjusts information such as operating pressure, flushing flow rate, and flushing time in real time. This significantly reduces the energy consumption and cost of high-salinity wastewater treatment and alleviates membrane fouling, showing significant application prospects.

[0082] Obviously, the above embodiments of this disclosure are merely examples for clear illustration and are not intended to limit the implementation of this disclosure. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure should be included within the scope of protection of the claims of this disclosure.

Claims

1. A novel dynamic reverse osmosis and nanofiltration ultra-high concentration system, characterized in that, The system includes 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. 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 environment. 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 second three-way valve has its fifth opening connected to the second nanofiltration opening of the nanofiltration system, its sixth opening connected to the inlet of the second circulating pump, and its outlet connected to the second piston assembly opening of the piston assembly via a second valve. The piston assembly's fourth piston assembly opening is connected to the seventh opening of the third three-way valve, its eighth opening connected to the first nanofiltration opening of the nanofiltration system, and its ninth opening connected to the inlet of the first circulating pump. The outlet of the first circulating pump is connected to the first piston assembly opening of the piston assembly via a first valve.

2. The concentration system according to claim 1, characterized in that, The piston assembly includes a piston, with a first piston assembly opening and a third piston assembly opening located on one side of the piston, and a second piston assembly opening and a fourth piston assembly opening located on the other side of the piston.

3. The concentration system according to any one of the preceding claims, characterized in that, The nanofiltration system is equipped with a nanofiltration membrane, and the first nanofiltration opening and the second nanofiltration opening of the nanofiltration system are located at both ends of the nanofiltration membrane, respectively.

4. The concentration system according to any one of the preceding claims, characterized in that, In the 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 first brine. The first brine passes through the first opening and the second opening of the first three-way valve to reach the first piston assembly opening of the piston assembly. The first brine pushes the piston in the piston assembly to move towards the side of the second piston assembly opening, so that the second brine 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 to reach the first nanofiltration opening of the nanofiltration system. The second brine passes through the nanofiltration membrane from one side of the first nanofiltration opening. The second brine leaves from the second nanofiltration opening and passes through the fifth opening and the sixth opening of the second three-way valve to reach the second circulation pump, which pumps it to the piston assembly.

5. The concentration system according to any one of the preceding claims, characterized in that, In the second state, when the concentration system is in the second state, the first pump supplies liquid to the reverse osmosis system. The liquid passes through the reverse osmosis system to produce purified liquid and third brine. The third brine passes sequentially through the first and third openings of the first three-way valve to the second piston assembly opening of the piston assembly. The third brine pushes the piston in the piston assembly to move towards one side of the first piston assembly opening, causing the fourth brine in the piston assembly to leave from the third piston assembly opening and sequentially pass through the fourth and fifth openings of the second three-way valve to reach the second nanofiltration opening of the nanofiltration system. The fourth brine passes through the nanofiltration membrane from one side of the second nanofiltration opening. The fourth brine leaves from the first nanofiltration opening and sequentially passes through the eighth and ninth openings of the third three-way valve to reach the first circulation pump, which pumps it to the piston assembly.

6. The concentration system according to any one of the preceding claims, characterized in that, When the concentration system is in the first state, the rate at which the second brine passes through the nanofiltration membrane is constant; when the concentration system is in the second state, the rate at which the fourth brine passes through the nanofiltration membrane is constant.

7. The concentration system according to any one of the preceding claims, characterized in that, It also includes a liquid extraction device. When the concentration system is in the first waste liquid discharge state, the second brine is drawn out from the opening of the fourth piston assembly by the liquid extraction 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 by the liquid extraction device. When the concentration system is in the second waste liquid discharge state, the fourth brine is drawn out from the opening of the third piston assembly by the liquid extraction 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 by the liquid extraction device.

8. The concentration system according to any one of the preceding claims, characterized in that, 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, and the outlet of which is connected to the first pump. Conductivity meters are provided at the inlet and outlet of the raw material tank, respectively.

9. The concentration system according to any one of the preceding claims, characterized in that, When the concentration system is in the cleaning state, the liquid is sequentially transported from the raw material tank to the reverse osmosis system and the high-pressure nanofiltration system under the action of the first pump, and finally returned to the raw material tank.

10. The concentration system according to any one of the preceding claims, characterized in that, A sodium bed is provided between the raw material tank and the first pump, and the sodium bed is used to remove calcium and magnesium ions from the liquid.

11. The concentration system according to any one of the preceding claims, characterized in that, The nanofiltration system further includes a third nanofiltration opening through which the liquid in the nanofiltration system can be transported to the inlet of the sodium bed; When the concentration system is in the first state, the liquid flows sequentially through the sodium bed, the first pump, the reverse osmosis system, the piston assembly, and the nanofiltration system to return to the sodium bed; When the concentration system is in the second state, the liquid flows sequentially through the sodium bed, the first pump, the reverse osmosis system, the piston assembly, and the nanofiltration system to return to the sodium bed.

12. The concentration system according to any one of the preceding claims, characterized in that, The reverse osmosis system includes a reverse osmosis membrane, through which liquid is purified to obtain the purified liquid.

13. A wastewater treatment method, characterized in that, Wastewater is treated using the concentration system described in any of the preceding claims.

14. The wastewater treatment method according to claim 13, 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 sequentially 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.

15. The wastewater treatment method according to claim 13 or 14, characterized in that, The cleaning state includes a first cleaning state and a second cleaning state. A conductivity meter is installed in the pipeline from the nanofiltration system to the raw material tank to detect the conductivity of the brine in the pipeline. The concentration system changes sequentially in the following order: 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. In the first cleaning state, when the change in conductivity is less than the set tolerance, the first cleaning state ends and the process enters the second state. In the second cleaning state, the second cleaning state ends when the change in conductivity is less than the set tolerance.

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