Device for extracting humic acid from percolate nanofiltration concentrated solution through coupled desalination

Abstract

The utility model relates to the technical field of landfill leachate treatment, and particularly discloses a coupling desalting device for extracting humic acid from a nanofiltration concentrated solution of leachate, which comprises a flowing electrode capacitive deionization mechanism, an ultrafiltration mechanism and a microfiltration mechanism, the flowing electrode capacitive deionization mechanism comprises an anode collector plate for collecting positive ions and a cathode collector plate for collecting negative ions; electrode liquid for collecting ions is arranged in the anode collector plate and the cathode collector plate, and the collector surface of the anode collector plate and the collector surface of the cathode collector plate are oppositely arranged to form a water passing channel with an electric field; a water inlet of the ultrafiltration mechanism is used for introducing a leachate nanofiltration concentrated solution, a water outlet of the ultrafiltration mechanism is communicated with the water passing channel, and the ultrafiltration mechanism is used for filtering and intercepting humic acid; the microfiltration mechanism is communicated with the anode collector plate and the cathode collector plate, and is used for filtering ions in the electrode liquid, so that the problem of low separation efficiency of divalent salt in the leachate in the existing humic acid extraction technology is thoroughly solved.

Description

Technical Field

[0001] The utility model relates to the technical field of garbage leachate treatment, in particular to a device for extracting humic acid from leachate nanofiltration concentrate coupled with desalination. Background Art

[0002] At present, the main method used for treating urban garbage in my country is sanitary landfill. However, a large amount of leachate will be generated in the process of sanitary landfill. The humic acid content in the leachate is very high, especially the humic acid content in the middle-aged and old leachate is generally above 50%. Humic acid is a potential organic resource widely existing in the natural environment. In agriculture, it is a widely recognized new fertilizer with the effects of improving soil aggregate structure, fixing phosphorus and potassium, reducing nitrogen leaching, and stimulating plant growth. The economic value and application prospects of extracting humic acid from the nanofiltration concentrate of leachate to achieve resource recycling are very high. However, high-concentration leachate may be difficult to be directly used as a liquid fertilizer containing humic acid due to excessive salt content, which is easy to inhibit plant growth. It is necessary to separate the divalent salt in the leachate from the humic acid in the process. Therefore, the resource extraction and utilization of humic acid in the leachate requires the separation of salt.

[0003] In the prior art, there is a device for extracting humic acid from leachate nanofiltration concentrate, a method for deep treatment of landfill leachate coupled with humic acid extraction of nanofiltration concentrate (application number: 201910626655.2), in which the leachate nanofiltration concentrate passes through a two-stage ultrafiltration system and the secondary ultrafiltration permeate directly enters a gypsum crystallization system for desalination. However, this method and device require a large amount of desalting drugs to achieve the separation of divalent salts, which makes the separation efficiency of divalent salts in the leachate low.

[0004] Therefore, it is necessary to study a device that can efficiently separate humic acid and salt in leachate, which has practical value. Utility Model Content

[0005] The utility model aims to provide a humic acid extraction device for leachate nanofiltration concentrate coupled with desalination, which realizes efficient separation of divalent salts through a mobile electrode capacitive deionization device to solve the problem of low separation efficiency of divalent salts in leachate in the existing humic acid extraction technology.

[0006] In order to solve the above technical problems, the utility model provides a device for extracting humic acid from leachate nanofiltration concentrate coupled with desalination.

[0007] It includes a flow electrode capacitive deionization mechanism, an ultrafiltration mechanism and a microfiltration mechanism;

[0008] The mobile electrode capacitive deionization mechanism includes an anode current collecting plate for collecting cations and a cathode current collecting plate for collecting anions;

[0009] The anode current collecting plate and the cathode current collecting plate are both provided with an electrode liquid for collecting ions, and the current collecting surface of the anode current collecting plate is arranged opposite to the current collecting surface of the cathode current collecting plate to form a water passage with an electric field;

[0010] The water inlet of the ultrafiltration mechanism is used to introduce the leachate nanofiltration concentrate, the water outlet of the ultrafiltration mechanism is connected to the water passage, and the ultrafiltration mechanism is used to filter and intercept the humic acid;

[0011] The microfiltration mechanism is communicated with both the anode current collecting plate and the cathode current collecting plate, and the microfiltration mechanism is used for filtering ions in the electrode liquid.

[0012] In some embodiments, the distance between the anode current collecting plate and the cathode current collecting plate is 3-4 mm.

[0013] In some embodiments, the ultrafiltration mechanism includes a primary ultrafiltration component and a secondary ultrafiltration component;

[0014] The water inlet of the first-level ultrafiltration component is used to pass the leachate nanofiltration concentrate, the first water outlet of the first-level ultrafiltration component is connected to the water passage, the second water outlet of the first-level ultrafiltration component is connected to the second-level ultrafiltration component, and the first-level ultrafiltration component is used to filter and retain the humic acid;

[0015] The secondary ultrafiltration component is used for filtering and retaining the humic acid again.

[0016] In some embodiments, a first check valve and a first centrifugal pump are provided between the primary ultrafiltration component and the water passage.

[0017] In some of the embodiments, the microfiltration mechanism includes a storage chamber and a filter for filtering ions;

[0018] The storage chamber is communicated with the anode current collecting plate to form a first communication loop, and the storage chamber is communicated with the cathode current collecting plate to form a second communication loop;

[0019] In the loop of the electrode liquid returning to the anode current collecting plate, the filter screen and the second centrifugal pump are provided on the first communication loop;

[0020] In the loop for the electrode liquid to flow back to the cathode current collecting plate, the filter screen and the third centrifugal pump are provided on the second communication loop.

[0021] In some embodiments, the pore size of the filter is 0.1-10 μm.

[0022] In some of the embodiments, a water inlet device is further included;

[0023] The water inlet device is connected with the ultrafiltration mechanism and the water passage to form a third flow loop.

[0024] In some of these embodiments, a crystallization mechanism is also included;

[0025] The crystallization mechanism is communicated with the microfiltration mechanism, and the crystallization mechanism is used to precipitate ions in the electrode solution.

[0026] The beneficial effects of the utility model are as follows:

[0027] In the present scheme, the mobile electrode capacitor deionization mechanism includes an anode current collecting plate for collecting cations and a cathode current collecting plate for collecting anions, and a water passage with an electric field formed by the two. When used, the wastewater is firstly dehumiced by an ultrafiltration component, leaving the ion-containing wastewater, and the wastewater is passed into the water passage with an electric field, and the anions and cations enter the anode current collecting plate and the cathode current collecting plate respectively. The electrode liquid containing the anions and cations is filtered by the microfiltration component to achieve desalination of the wastewater. Compared with the prior art, the present scheme uses a mobile electrode capacitor deionization mechanism with low energy consumption, and the mobile electrode capacitor deionization mechanism has a high salt removal efficiency for high-salinity water, the electrode preparation is simple, the adsorption capacity is large, and the material can be regenerated outside the device. It can continuously and stably treat saline wastewater of different concentrations, so it is simple, efficient and economical, avoiding the need to consume a large amount of desalination drugs to achieve desalination as in the prior art, and completely solves the problem of low separation efficiency of divalent salts in leachate in the prior humic acid extraction technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the implementation mode will be briefly introduced below. Obviously, the drawings described below are only some implementation modes of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a schematic top view of the overall device structure provided by the preferred embodiment of the utility model;

[0030] Figure 2 It is a front view schematic diagram of the overall device structure provided by the preferred embodiment of the utility model.

[0031] The reference numerals are as follows:

[0032] 1. Water inlet device; 2. Ultrafiltration mechanism; 20. Primary ultrafiltration component; 21. Secondary ultrafiltration component; 3. Flow electrode capacitor deionization mechanism; 30. Anode current collecting plate; 31. Cathode current collecting plate; 32. Water passage; 4. Microfiltration mechanism; 40. Storage chamber; 5. Crystallization mechanism; 6. Frame; 7. Humic acid storage device; 8. Secondary ultrafiltration permeate storage device; a1. First check valve; a2. Second check valve; a3. Third check valve; a4. Fourth check valve; a5. Fifth check valve; a6. Sixth check valve; a7. First centrifugal pump; a8. Second centrifugal pump; a9. Third centrifugal pump; a10. Fourth centrifugal pump; a11. Fifth centrifugal pump; a12. Sixth centrifugal pump; a13. First pressure gauge; a14. Second pressure gauge; a15. Third pressure gauge; a16. First flow meter; a17. Second flow meter. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0034] In the prior art, there is a problem of low desalination efficiency in the humic acid extraction device coupled with desalination. In order to solve this problem, this scheme proposes a humic acid extraction device for leachate nanofiltration concentrate coupled with desalination, which realizes efficient desalination while achieving humic acid extraction by setting a mobile electrode capacitor deionization mechanism for desalination and an ultrafiltration mechanism for extracting humic acid. The specific embodiments will be described below.

[0035] Embodiment 1

[0036] Please refer to Figure 1 and Figure 2 , including a flowing electrode capacitive deionization mechanism 3 (FCDI, FCDI referred to below is the flowing electrode capacitive deionization mechanism 3), an ultrafiltration mechanism 2 and a microfiltration mechanism 4; the flowing electrode capacitive deionization mechanism 3 includes an anode current collecting plate 30 for collecting cations and a cathode current collecting plate 31 for collecting anions; the anode current collecting plate 30 and the cathode current collecting plate 31 are both provided with an electrode liquid for collecting ions, and the collecting surface of the anode current collecting plate 30 is arranged opposite to the collecting surface of the cathode current collecting plate 31 to form a water passage 32 with an electric field; the water inlet of the ultrafiltration mechanism 2 is used to pass the leachate nanofiltration concentrate, the water outlet of the ultrafiltration mechanism 2 is connected to the water passage 32, and the ultrafiltration mechanism 2 is used to filter and retain humic acid; the microfiltration mechanism 4 is connected to the anode current collecting plate 30 and the cathode current collecting plate 31, and the microfiltration mechanism 4 is used to filter the ions in the electrode liquid.

[0037] When used, the leachate nanofiltration concentrate is first passed into the ultrafiltration mechanism 2 for filtration to produce a retentate and a permeate, wherein the retentate is the humic acid to be extracted, and the permeate is passed into the water passage 32 in the flowing electrode capacitor deionization mechanism 3. Under the action of the electric field, the cations in the permeate pass through the collecting surface of the anode current collecting plate 30, enter the anode current collecting plate 30 and are adsorbed by the electrode liquid; the anions in the permeate pass through the collecting surface of the anode current collecting plate 30, enter the cathode current collecting plate 31 and are adsorbed by the electrode liquid. Subsequently, the electrode liquid adsorbed with ions is filtered through the microfiltration component to achieve ion desorption and desalination. After adopting this setting, the present scheme can realize the humic acid extraction of the leachate nanofiltration concentrate through the ultrafiltration component, and realize the salt desorption of the leachate nanofiltration concentrate through the flowing electrode capacitor deionization mechanism 3.

[0038] Regarding the above-mentioned mobile electrode capacitive deionization mechanism 3, as Figure 1 and Figure 2 As shown, the anode current collecting plate 30 and the cathode current collecting plate 31 in the flowing electrode capacitive deionization mechanism 3 are both provided with flowing electrode flow channels, which are connected with the microfiltration mechanism 4 and are used for the flowing electrode liquid to enter and exit, and the collecting surface on the anode current collecting plate 30 is a cation exchange membrane, and the collecting surface on the cathode current collecting plate 31 is an anion exchange membrane. When used, the permeate is drawn into the water passage 32 at the bottom of the flowing electrode capacitive deionization mechanism 3 at a certain flow rate, and the ions in the water passage 32 pass through the exchange membrane and are adsorbed by the electrode liquid under the action of the electric field, and the permeate with the ions removed flows out from the top of the water passage 32, thereby effectively removing the high concentration of Ca in the permeate. 2 + Mg 2+ 、SO4 2- Plasma.

[0039] The electric field formed between the anode current collecting plate 30 and the cathode current collecting plate 31 may be externally applied or directly formed by the electrical connection between the anode current collecting plate 30 and the cathode current collecting plate 31 and the power supply component. Therefore, those skilled in the art may choose according to their actual needs.

[0040] It should be pointed out that the material of the anode current collecting plate 30 and the cathode current collecting plate 31 is high-purity graphite; the water channel 32 is composed of a silica gel plate, and sealed water inlets and outlets are respectively provided at both ends of the silica gel plate, and the inlet and outlet of the permeate are realized through the water inlet and outlet devices. For example, a medical injection needle can be used to achieve the purpose of the permeate entering and exiting the water channel 32; the electrode liquid of the flowing electrode is mixed with biochar to efficiently adsorb ions and effectively increase the conductivity.

[0041] Furthermore, in order to improve the ion separation effect, the distance between the anode current collecting plate 30 and the cathode current collecting plate 31 is preferably 3 to 4 mm.

[0042] Preferably, in this embodiment, the substrate spacing used by FCDI is 3-4 mm, the DC regulated voltage supply voltage is 1.2-4 V, the water inlet flow rate is 15-20 mL / min, the flow electrode flow rate is 100-150 mL / min, and the electrosorption time is 3-4 h.

[0043] After adopting the mobile electrode capacitive deionization component (FCDI), the purpose of separating humic acid and divalent salt can be achieved. Compared with the existing technology, its application has the advantages of simple reaction device structure, low operating cost, no need to add chemical agents, simple operation, easy implementation of automatic control and online monitoring, low energy consumption, and the FCDI system has a high salt removal efficiency for high-salinity water, simple electrode preparation, large adsorption capacity, and the material can be regenerated outside the device. It can continuously and stably treat salt-containing wastewater of different concentrations, so it is simple, efficient and economical, and has more advantages in treating nanofiltration concentrates with large changes in water quality; at the same time, the device uses the FCDI system to concentrate and enrich salt ions and then performs crystallization salt treatment. Compared with the existing technology, the processing volume is reduced, the drug consumption is reduced, the processing efficiency is higher, and it is more economical and efficient.

[0044] Regarding the above-mentioned microfiltration mechanism 4, as Figure 1 and Figure 2 As shown, the microfiltration mechanism 4 includes a storage chamber 40 and a filter for filtering biochar in the electrode liquid arranged in the storage chamber 40; the storage chamber 40 is connected with the anode current collecting plate 30 to form a first connecting loop, and the storage chamber 40 is connected with the cathode current collecting plate 31 to form a second connecting loop; on the loop of the electrode liquid returning to the anode current collecting plate 30, a filter screen and a second centrifugal pump a8 are provided on the first connecting loop; on the loop of the electrode liquid returning to the cathode current collecting plate 31, a filter screen and a third centrifugal pump a9 are provided on the second connecting loop. When used, the electrode liquid of the anode current collecting plate 30 flows into the storage chamber 40 by its own weight and ions are desorbed through the filter screen, and the electrode liquid of the cathode current collecting plate 31 also flows into the storage chamber 40 by its own weight and ions are desorbed through the filter screen, and the desorbed electrode liquid is pumped into the anode current collecting plate 30 and the cathode current collecting plate 31 respectively by the second centrifugal pump a8 and the third centrifugal pump a9, and the permeate with high salt flows out of the storage chamber 40.

[0045] Specifically, the storage chamber 40 is provided with four through holes, two of which are respectively connected to the flow electrode flow channel of the anode current collecting plate 30 through pipes to form a first connecting loop, the electrode liquid circulates in the anode current collecting plate 30 and the storage chamber 40, and a second centrifugal pump a8 is provided on the pipe returning to the flow electrode flow channel. Similarly, the other two through holes are respectively connected to the flow electrode flow channel of the cathode current collecting plate 31 through pipes to form a second connecting loop, the electrode liquid circulates in the cathode current collecting plate 31 and the storage chamber 40, and a third centrifugal pump a9 is provided.

[0046] Preferably, the pore size of the filter is 0.1-10 μm, and the operating pressure is 0.1-0.3 MPa. Preferably, the filter can be a hollow fiber membrane.

[0047] It should be pointed out that microfiltration (MF) is the earliest developed and widely used membrane filtration separation technology; microfiltration is used to separate particles of 0.02 to 10 μm, and the pressure range required for the process is 0.07 to 0.2 MPa. Microfiltration can be used to intercept particles, bacteria, pollutants, etc. from gas and liquid phases, and is a necessary means to ensure product quality in modern industry.

[0048] Regarding the above-mentioned ultrafiltration mechanism 2, as Figure 1 and Figure 2 As shown, the ultrafiltration mechanism 2 includes a primary ultrafiltration component 20 and a secondary ultrafiltration component 21; the water inlet of the primary ultrafiltration component 20 is used to pass the leachate and nanofiltration concentrate, the first water outlet of the primary ultrafiltration component 20 is connected to the water passage 32, and the second water outlet of the primary ultrafiltration component 20 is connected to the secondary ultrafiltration component 21. The primary ultrafiltration component 20 is used to filter and retain humic acid; the secondary ultrafiltration component 21 is used to filter and retain humic acid again. When used, the leachate and nanofiltration concentrate first enter the primary ultrafiltration component 20 for filtration to obtain the primary ultrafiltration retained liquid and the primary ultrafiltration permeate, wherein the primary ultrafiltration The filtered permeate enters the water passage 32 in the mobile electrode capacitor deionization mechanism 3 as the permeate for desalination, and the primary ultrafiltration retentate is passed into the secondary ultrafiltration component 21 for secondary filtration to obtain the secondary ultrafiltration retentate and the secondary ultrafiltration permeate, wherein the secondary ultrafiltration permeate is the humic acid concentrated liquid, which can be stored through the humic acid storage device 7 and can reach the concentration that can be reused as humic acid water-soluble fertilizer, and the secondary ultrafiltration permeate can be stored through the secondary ultrafiltration permeate storage device 8. The secondary ultrafiltration permeate contains a small amount of small molecular humic acid and has a low salt ion concentration, and can be returned to the nanofiltration unit for treatment.

[0049] Among them, a first pressure gauge a13, a first check valve a1, a first centrifugal pump a7 and a first flowmeter a16 are provided between the first-stage ultrafiltration component 20 and the centrifugal pump of the water passage 32; a second check valve a2 is also provided between the first-stage ultrafiltration component 20 and the second-stage ultrafiltration component 21; a fourth centrifugal pump a10, a third check valve a3 and a second pressure gauge a14 are provided between the second-stage ultrafiltration component 21 and the second-stage ultrafiltration permeate storage 8; a second flowmeter a17 and a fourth check valve a4 are provided between the second-stage ultrafiltration component 21 and the humic acid storage 7.

[0050] Preferably, in this embodiment, the ultrafiltration membrane used in the first-stage ultrafiltration component 20 has a molecular weight cutoff of 500 to 2500Da, an operating pressure of 0.5 to 2.5MPa, and a concentration multiple of 4 to 12 times; the ultrafiltration membrane used in the second-stage ultrafiltration component 21 has a molecular weight cutoff of 1000 to 5000Da, an operating pressure of 0.5 to 2.0MPa, and a concentration multiple of 3 to 10 times.

[0051] It is particularly pointed out that ultrafiltration components are essential instruments for new drug research and development, small-scale sample preparation, ultrafiltration separation and concentration, and processing of biological macromolecule samples in current technology. The automatic ultrafiltration system uses modern control elements and touch screen buttons, which are easy to operate. Control points such as target concentration and some safe operating parameters such as pressure can be set for automatic control to achieve the purpose of automatic operation. It can be completely cleaned and can be cleaned online.

[0052] Furthermore, in order to achieve the output of desalination, such as Figure 1 and Figure 2 , and also includes a crystallization mechanism 5, which is connected to the microfiltration mechanism 4. The crystallization mechanism is used to precipitate the salt in the permeate flowing out of the microfiltration mechanism 4. When used, the supersaturated high-salt permeate is added with crystal seeds to induce directional crystallization of supersaturated salt, thereby achieving the purpose of desalination.

[0053] Among them, a fifth centrifugal pump a11 and a fifth check valve a5 are provided between the crystallization mechanism and the storage chamber 40 .

[0054] Preferably, in this embodiment, the reaction pH value in the crystallization mechanism 5 is 4-6, the reaction temperature is 20-30° C., the stirring speed is 20-80 rpm, and the time is 4 hours.

[0055] Furthermore, in order to reduce the strainer burden of the ultrafiltration mechanism 2, as Figure 1 and Figure 2 , and also includes a water inlet device 1; the water inlet device 1 is connected to the ultrafiltration mechanism 2 and the water passage 32 to form a third circulation loop. When in use, the effluent of the mobile electrode capacitive deionization mechanism 3 flows out from the top and returns to the water inlet device 1 to mix with the initial leachate nanofiltration concentrate. After the deionized effluent is returned to the inlet, the divalent ion concentration of the system inlet water is reduced, making the process more perfect.

[0056] A nanofiltration treatment unit is provided in the water inlet device 1, and the wastewater is nanofiltered by the nanofiltration treatment unit to obtain a mixture of leachate and nanofiltration concentrate. After adopting this setting, nanofiltration plays an enrichment role for divalent ions, and the enrichment leads to a high concentration of divalent salts in the system, reducing membrane flux and increasing system losses. In addition, divalent ions will cause more humic acid molecules to be adsorbed on the membrane, increasing membrane pollution. The processing capacity of the nanofiltration unit is used to treat the first-level ultrafiltration permeate and then meet the discharge standards, thereby achieving the purpose of reducing investment, land cost, harmless treatment and pollution control. At the same time, the utility model uses the humic acid in the leachate as a water-soluble fertilizer for resource extraction, thereby achieving full treatment of the nanofiltration concentrate and recycling of humic acid resources.

[0057] Among them, a sixth centrifugal pump a12, a sixth check valve a6 and a third pressure gauge a15 are provided between the water inlet device 1 and the first-stage ultrafiltration component 20.

[0058] In some embodiments, in addition to forming the third flow loop, the water inlet device 1 is also connected to the secondary ultrafiltration permeate storage 8, so as to achieve the reflux and reuse of the permeate.

[0059] Furthermore, in order to increase the service life of the device, Figure 1 and Figure 2 , and also includes a frame 6, on which the above-mentioned water inlet device 1, ultrafiltration mechanism 2, mobile electrode capacitor deionization mechanism 3, microfiltration mechanism 4 and crystallization mechanism 5 are installed.

[0060] Furthermore, in order to improve the control convenience, it also includes a control mechanism, which is electrically connected to the water inlet device 1, the ultrafiltration mechanism 2, the flow electrode capacitor deionization mechanism 3, the microfiltration mechanism 4, the crystallization mechanism 5, each check valve, each centrifugal pump, each pressure gauge and each flow meter to facilitate the control of the process flow.

[0061] In summary, the utility model provides a device for extracting humic acid from leachate nanofiltration concentrate, which uses two-stage ultrafiltration components and FCDI to reduce the burden of the membrane and increase the service life of the membrane; FCDI provides continuous and efficient desalination performance, and makes full use of the nanofiltration treatment unit to treat the first-stage ultrafiltration permeate to reduce investment. It is advanced, practical, economical and reliable, does not require external dosing, and the preparation of the device is simple and economical. It achieves the purpose of harmless resource utilization of leachate nanofiltration concentrate humic acid and concentrated liquid deep treatment, and has economic and environmental benefits.

[0062] Embodiment 2

[0063] The second embodiment of the present application adopts the device in the first embodiment and provides a method for extracting humic acid from a leachate nanofiltration concentrate coupled with desalination, which specifically includes the following steps:

[0064] 1) The leachate and nanofiltration concentrate are mixed together in the water inlet device and pumped into the first-stage ultrafiltration component for separation and concentration to obtain the first-stage ultrafiltration retentate and the first-stage ultrafiltration permeate.

[0065] 2) The obtained first-stage ultrafiltration retentate is pumped into the second-stage ultrafiltration component for separation and concentration to obtain the second-stage ultrafiltration retentate and the second-stage ultrafiltration permeate.

[0066] 3) The secondary ultrafiltration retentate produced by the secondary ultrafiltration component has a humic acid concentration greater than 30g / L and can enter the humic acid collection pool and be reused as humic acid water-soluble fertilizer.

[0067] 4) The secondary ultrafiltration permeate produced by the secondary ultrafiltration component is pumped into the water inlet device and returned to the nanofiltration treatment unit for treatment together with the leachate MBR effluent.

[0068] 5) The first-stage ultrafiltration permeate produced by the first-stage ultrafiltration component is pumped into the FCDI. The first-stage ultrafiltration permeate is pumped into the bottom of the FCDI at a certain flow rate, and the effluent flows out from the top and returns to the water inlet device to mix with the initial leachate nanofiltration concentrate.

[0069] 6) The anode electrode liquid and cathode electrode liquid in FCDI are pumped into the anode and cathode current collecting plates of FCDI respectively through the microfiltration system and the centrifugal pump. The salt ions enriched in FCDI are pumped out into the microfiltration system along with the electrode liquid in the flowing electrode. The intercepted liquid retains the carbon and is reused in the flowing electrode of the FCDI system. The permeate enriched with salt ions enters the crystallization mechanism for treatment through the centrifugal pump.

[0070] Embodiment 3

[0071] The third embodiment of the present application adopts the device of the first embodiment and the method of the second embodiment, and takes the deep treatment of humic acid of the nanofiltration concentrated liquid of the extracted leachate of a domestic waste leachate treatment plant as an example, and the details are as follows:

[0072] The scale of the leachate treatment project of the domestic waste leachate treatment plant is 1,000 tons / day. The main leachate treatment system adopts the MBR+NF treatment process. The nanofiltration concentrate produced by the leachate treatment plant is lifted by a pump into the first-level ultrafiltration component. The ultrafiltration membrane used in the first-level ultrafiltration component is an anti-pollution high-salt permeability ultrafiltration membrane with a molecular weight cutoff of 1,000Da, an operating pressure of 1.0MPa, and a concentration multiple of 5 times. After membrane separation, a first-level ultrafiltration permeate and a first-level ultrafiltration retentate are produced. The first-level ultrafiltration permeate is a light yellow liquid with a COD of 1,000 to 1,500 mg. / L, conductivity 15 ~ 25mS / cm; the first-stage ultrafiltration retentate is a black reddish brown liquid, COD20000 ~ 30000mg / L, conductivity 15 ~ 25Ms / cm, humic acid concentration of 15000 ~ 22000mg / L; the first-stage ultrafiltration permeate is refluxed to the nanofiltration treatment unit and treated together with the leachate MBR effluent, and the first-stage ultrafiltration retentate is pumped into the second-stage ultrafiltration component, wherein the ultrafiltration membrane used in the second-stage ultrafiltration component is an anti-pollution high salt permeability ultrafiltration membrane, with a molecular weight cutoff of 2000Da, an operating pressure of 1.5MPa, and a concentration multiple of 1.5MPa. 10 times; after membrane separation, secondary ultrafiltration permeate and secondary ultrafiltration retentate are produced, wherein the secondary ultrafiltration permeate is a yellow-brown transparent liquid, COD is 3500-7500 mg / L, conductivity is 15-25 mS / cm; the secondary ultrafiltration retentate is a black liquid, COD is 65000-80000 mg / L, conductivity is 18-28 Ms / cm, humic acid concentration is 30000-45000 mg / L; at this time, the secondary ultrafiltration retentate meets the requirements and can be produced as a raw material for water-soluble fertilizer containing humic acid, and the secondary ultrafiltration permeate is pumped into the FCDI system through the flow Moving electrode capacitive deionization and desalination, in which the FCDI system uses a substrate spacing of 3mm, a DC regulated voltage supply voltage of 1.5V, an inlet flow rate of 15mL / min, a mobile electrode flow rate of 120mL / min, and an electrical adsorption time of 3h; the FCDI effluent and ion concentrations are greatly reduced, and are returned to the inlet pool and pumped into the primary ultrafiltration component together with the nanofiltration concentrate of the landfill leachate to reduce the inlet divalent salt concentration, and the electrode liquid enriched with ions in the mobile electrode is pumped out, and the carbon is intercepted by the microfiltration mechanism and reused for the mobile electrode, and the permeate is treated with crystallized salt.

[0073] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the protection scope of the present invention.

Claims

1. A device for extracting humic acid from leachate nanofiltration concentrate coupled with desalination, characterized in that: It includes a flow electrode capacitive deionization mechanism, an ultrafiltration mechanism and a microfiltration mechanism; The mobile electrode capacitive deionization mechanism includes an anode current collecting plate for collecting cations and a cathode current collecting plate for collecting anions; The anode current collecting plate and the cathode current collecting plate are both provided with an electrode liquid for collecting ions, and the current collecting surface of the anode current collecting plate is arranged opposite to the current collecting surface of the cathode current collecting plate to form a water passage with an electric field; The water inlet of the ultrafiltration mechanism is used to introduce the leachate nanofiltration concentrate, the water outlet of the ultrafiltration mechanism is connected to the water passage, and the ultrafiltration mechanism is used to filter and intercept the humic acid; The microfiltration mechanism is communicated with both the anode current collecting plate and the cathode current collecting plate, and the microfiltration mechanism is used for filtering ions in the electrode liquid.

2. The device for extracting humic acid from leachate nanofiltration concentrate coupled with desalination according to claim 1, characterized in that: The distance between the anode current collecting plate and the cathode current collecting plate is 3-4 mm.

3. The device for extracting humic acid from leachate nanofiltration concentrate coupled with desalination according to claim 1, characterized in that: The ultrafiltration mechanism includes a primary ultrafiltration component and a secondary ultrafiltration component; The water inlet of the first-level ultrafiltration component is used to pass the leachate nanofiltration concentrate, the first water outlet of the first-level ultrafiltration component is connected to the water passage, the second water outlet of the first-level ultrafiltration component is connected to the second-level ultrafiltration component, and the first-level ultrafiltration component is used to filter and retain the humic acid; The secondary ultrafiltration component is used for filtering and retaining the humic acid again.

4. The device for extracting humic acid from leachate nanofiltration concentrate coupled with desalination according to claim 3, characterized in that: A first check valve and a first centrifugal pump are provided between the primary ultrafiltration component and the water passage.

5. The device for extracting humic acid from leachate nanofiltration concentrate coupled with desalination according to claim 1, characterized in that: The microfiltration mechanism includes a storage chamber and a filter screen; The storage chamber is communicated with the anode current collecting plate to form a first communication loop, and the storage chamber is communicated with the cathode current collecting plate to form a second communication loop; In the loop of the electrode liquid returning to the anode current collecting plate, the filter screen and the second centrifugal pump are provided on the first communication loop; In the loop for the electrode liquid to flow back to the cathode current collecting plate, the filter screen and the third centrifugal pump are provided on the second communication loop.

6. The device for extracting humic acid from leachate nanofiltration concentrate coupled with desalination according to claim 5, characterized in that: The pore size of the filter is 0.1-10 μm.

7. The device for extracting humic acid from leachate nanofiltration concentrate coupled with desalination according to claim 1, characterized in that: It also includes a water inlet device; The water inlet device is connected with the ultrafiltration mechanism and the water passage to form a third flow loop.

8. The device for extracting humic acid from leachate nanofiltration concentrate coupled with desalination according to claim 1, characterized in that: It also includes crystallization mechanisms; The crystallization mechanism is communicated with the microfiltration mechanism, and the crystallization mechanism is used to precipitate salt in the permeate flowing out of the microfiltration mechanism.

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