Nanofiltration concentrated water resource utilization treatment device and method

Abstract

The invention provides a nanofiltration concentrated water resource utilization treatment device and method. The device comprises an ozone oxidation unit, a biological activated carbon filter column and a return pipeline, the ozone oxidation unit is connected with a desulfurization wastewater treatment system and is used for carrying out ozone oxidation treatment on nanofiltration concentrated water from the desulfurization wastewater treatment system; the biological activated carbon filter column is connected with the ozone oxidation unit and is used for carrying out organic matter removal treatment on the nanofiltration concentrated water subjected to ozone oxidation treatment by utilizing biological activated carbon; the backflow pipeline is connected with the biological activated carbon filter column and the desulfurization wastewater treatment system and is used for enabling the nanofiltration concentrated water subjected to organic matter removal treatment to flow back to the desulfurization wastewater treatment system so as to strengthen crystallization and separation of calcium sulfate. According to the nanofiltration concentrated water resource utilization treatment device and method provided by the invention, nanofiltration concentrated water is effectively treated, the removal efficiency of hardness of desulfurization wastewater is improved, and resource utilization of the nanofiltration concentrated water and energy conservation and emission reduction of the system are realized.

Description

Technical Field

[0001] The present application relates to the field of environmental engineering technology, and in particular to a device and method for resource utilization of nanofiltration concentrated water. Background Art

[0002] In recent years, due to the sharp increase in electricity consumption, the release of pollutants such as sulfur dioxide from coal combustion has increased significantly. Among flue gas desulfurization technologies, limestone gypsum wet desulfurization accounts for more than 90% of flue gas desulfurization processes due to its high efficiency and low cost. Nanofiltration technology is widely used in the salt separation treatment of limestone gypsum wet desulfurization wastewater. Nanofiltration technology can achieve Cl in desulfurization wastewater. - and SO4 2- Separation, in which the separated SO4 2- Entering the nanofiltration concentrated water. SO4 in the nanofiltration concentrated water 2- Can be combined with Ca in desulfurization wastewater 2+ The reaction generates CaSO4 slightly soluble precipitate, so as to utilize SO4 in the concentrated water through nanofiltration. 2- However, field measurements have shown that the chemical oxygen demand (COD) content in nanofiltration brine can be as high as 3400 mg / L. This high concentration of COD interferes with the formation of CaSO4 through brine recirculation. This phenomenon has long been ignored, seriously affecting the resource utilization of nanofiltration brine in desulfurization wastewater softening.

[0003] At present, the removal of Ca from desulfurization wastewater in coal-fired power plants 2+ Mg 2+ Commonly used methods are as follows Figure 1 The precipitation method shown in the figure. This process removes Ca in the desulfurization wastewater by softening the lime to precipitate CaSO4. 2+ and SO4 2- However, field measurements have shown that due to the interference of high COD concentration in the reflux nanofiltration concentrate, the Ca 2+ and SO4 2- Even if the concentration is higher than the critical value, CaSO4 precipitate will not form. This problem needs to be solved urgently. Summary of the Invention

[0004] In response to the problems in the prior art, the embodiments of the present application provide a nanofiltration concentrate resource utilization treatment device and method, which can solve the problem that the reflux of nanofiltration concentrate increases the organic matter content in the treatment system and affects the precipitation of calcium sulfate.

[0005] In a first aspect, the present application provides a nanofiltration concentrated water resource utilization treatment device, comprising: an ozone oxidation unit, a biological activated carbon filter column, and a reflux pipeline;

[0006] The ozone oxidation unit is connected to the desulfurization wastewater treatment system and is used for ozone oxidation treatment of the nanofiltration concentrate water from the desulfurization wastewater treatment system;

[0007] The biological activated carbon filter column is connected to the ozone oxidation unit and is used for removing organic matters from the nanofiltration concentrate water after ozone oxidation treatment by using biological activated carbon; the organic matter removal treatment includes physical adsorption treatment and enhanced degradation treatment of the nanofiltration concentrate water after ozone oxidation treatment by biological activated carbon and aerobic microorganisms attached to its surface;

[0008] The reflux pipeline is connected to the biological activated carbon filter column and the desulfurization wastewater treatment system and is used for refluxing the nanofiltration concentrate water after organic matter removal treatment to the desulfurization wastewater treatment system to enhance the crystallization and precipitation of calcium sulfate.

[0009] Further, the ozone oxidation unit includes: an ozone generator, a flow meter and an ozone oxidation device;

[0010] The ozone generator is used for generating ozone;

[0011] The flow meter is connected to the ozone generator and the ozone oxidation device and is used for measuring and controlling the dosage of ozone added;

[0012] The ozone oxidation device is connected to the desulfurization wastewater treatment system and is used for making the nanofiltration concentrate water from the desulfurization wastewater treatment system react fully with ozone.

[0013] Further, the biological activated carbon filter column includes: a filter column housing, a rectifying plate, a supporting layer and a filter material layer;

[0014] The nanofiltration concentrate water after ozone oxidation treatment is introduced through a water inlet pipe arranged at the bottom surface of the filter column housing;

[0015] The rectifying plate, the supporting layer and the filter material layer are arranged in the filter column housing in sequence from bottom to top;

[0016] The rectifying plate is used for making the nanofiltration concentrate water entering from the bottom surface of the filter column housing flow evenly upward to make it fully contact with the filter material layer;

[0017] The supporting layer is used for supporting the filter material layer to prevent the filter material from flowing away with the water flow;

[0018] The filter material layer is used for removing organic matters in the nanofiltration concentrate water through physical adsorption and microbial degradation; the nanofiltration concentrate water after organic matter removal treatment is discharged through a water outlet pipe arranged on one side of the filter column housing above the filter material layer.

[0019] Further, the biological activated carbon filter column further includes: a backwashing water inlet pipe;

[0020] The backwash inlet pipe is arranged at the top of the filter column housing and is used to backwash the biological activated carbon filter column regularly through the backwash inlet pipe to prevent the filter media from being blocked.

[0021] Further, when backwashing the biological activated carbon filter column, the inlet pipe is used to discharge the backwash wastewater.

[0022] Further, the biological activated carbon filter column further includes: a saturated carbon pipe;

[0023] The saturated carbon pipe is arranged on one side of the filter column housing at the filter media layer and is used to regularly discharge the filter media with saturated adsorption capacity.

[0024] Further, the filter media layer includes granular biological activated carbon; the support layer includes quartz sand.

[0025] Further, it further includes: a peristaltic pump;

[0026] The peristaltic pump is arranged between the ozone oxidation unit and the biological activated carbon filter column and is used to control the flow rate of the nanofiltration concentrate water after ozone oxidation treatment into the biological activated carbon filter column.

[0027] Further, it further includes: an adjustment tank;

[0028] The adjustment tank is arranged between the biological activated carbon filter column and the reflux pipeline and is used to store the nanofiltration concentrate water after organic matter removal treatment and control its flow rate back to the desulfurized wastewater treatment system.

[0029] In a second aspect, the present application provides a method for treating and recycling nanofiltration concentrate water, which is applied to the nanofiltration concentrate water treatment and recycling device described in any one of the above embodiments, and includes:

[0030] The ozone oxidation unit performs ozone oxidation treatment on the nanofiltration concentrate water from the desulfurized wastewater treatment system;

[0031] The biological activated carbon filter column uses biological activated carbon to perform organic matter removal treatment on the nanofiltration concentrate water after ozone oxidation treatment;

[0032] The reflux pipeline returns the nanofiltration concentrate water after organic matter removal treatment to the desulfurized wastewater treatment system to strengthen the crystallization and precipitation of calcium sulfate.

[0033] The present application provides a treatment device and method for the resource utilization of nanofiltration concentrated water. The device includes an ozone oxidation unit, a biological activated carbon filter column, and a reflux pipeline. The ozone oxidation unit is connected to a desulfurization wastewater treatment system and is used to perform ozone oxidation treatment on the nanofiltration concentrated water from the desulfurization wastewater treatment system. The biological activated carbon filter column is connected to the ozone oxidation unit and is used to remove organic matter from the nanofiltration concentrated water after ozone oxidation treatment by using biological activated carbon. The reflux pipeline is connected to the biological activated carbon filter column and the desulfurization wastewater treatment system and is used to reflux the nanofiltration concentrated water after organic matter removal treatment to the desulfurization wastewater treatment system to enhance the crystallization precipitation of calcium sulfate. The treatment device and method for the resource utilization of nanofiltration concentrated water provided by the present application effectively treat the nanofiltration concentrated water, improve the removal efficiency of the hardness of desulfurization wastewater, and realize the resource utilization of nanofiltration concentrated water and the energy conservation and emission reduction of the system.

[0034] Among them, the ozone oxidation unit efficiently decomposes the refractory organic matter in the nanofiltration concentrated water through ozone oxidation, reduces the COD and improves the biodegradability of the wastewater. The biological activated carbon filter column uses the synergistic effect of activated carbon adsorption and microbial degradation to deeply remove the residual dissolved organic matter and trace pollutants after ozone treatment. The reflux pipeline optimizes the calcium sulfate supersaturation environment by returning the treated water with low organic matter and high ion concentration to the desulfurization system, and strengthens the crystallization efficiency to reduce the scaling risk. Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] Figure 1 is the treatment method of desulfurization wastewater in a coal-fired power plant in the prior art;

[0037] Figure 2 is a schematic structural relationship diagram of a treatment device for the resource utilization of nanofiltration concentrated water and a desulfurization wastewater treatment system provided by an embodiment of the present application;

[0038] Figure 3 is a schematic process diagram of a treatment device for the resource utilization of nanofiltration concentrated water provided by an embodiment of the present application;

[0039] Figure 4 is a schematic structural diagram of a biological activated carbon filter column provided by an embodiment of the present application;

[0040] Figure 5 is a schematic flow diagram of a treatment method for the resource utilization of nanofiltration concentrated water provided by an embodiment of the present application;

[0041] Figure 6 is the Ca concentration change diagram of the solution after crystallization of different concentrations of COD in the actual nanofiltration concentrate water of a coal-fired power plant provided by an embodiment of the present application 2+ Concentration change diagram;

[0042] Figure 7 is the change of COD and the COD removal rate at different empty bed residence times provided by an embodiment of the present application;

[0043] Figure 8 is the change of UV at different empty bed residence times provided by an embodiment of the present application 254 Change;

[0044] Figure 9 is the change of UV and COD with time when ozone is introduced into the nanofiltration concentrate water provided by an embodiment of the present application 254 And COD change with time;

[0045] Figure 10 is the change of sulfate in the nanofiltration concentrate water at different empty bed residence times provided by an embodiment of the present application. Detailed implementation manners

[0046] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following further describes the embodiments of the present application in detail with reference to the drawings. Herein, the illustrative embodiments of the present application and their descriptions are used to explain the present application, but do not limit the present application. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be arbitrarily combined with each other.

[0047] Figure 2 is a schematic structural relationship diagram of a nanofiltration concentrate water resource utilization treatment device and a desulfurized wastewater treatment system provided by an embodiment of the present application. As Figure 2 shown, the nanofiltration concentrate water resource utilization treatment device provided by the present application includes: an ozone oxidation unit 1, a biological activated carbon filter column 2 and a reflux pipeline 3;

[0048] The ozone oxidation unit 1 is connected to the desulfurized wastewater treatment system 100 and is used for ozone oxidation treatment of the nanofiltration concentrate water from the desulfurized wastewater treatment system 100;

[0049] The biological activated carbon filter column 2 is connected to the ozone oxidation unit 1 and is used for removing organic matter from the nanofiltration concentrate water after ozone oxidation treatment by using biological activated carbon; the organic matter removal treatment includes physical adsorption treatment and enhanced degradation treatment of the nanofiltration concentrate water after ozone oxidation treatment by biological activated carbon and aerobic microorganisms attached to its surface;

[0050] The reflux pipeline 3 is connected to the biological activated carbon filter column 2 and the desulfurized wastewater treatment system 100, and is used to reflux the nanofiltration concentrate water after the removal of organic matter to the desulfurized wastewater treatment system 100 to strengthen the crystallization and precipitation of calcium sulfate.

[0051] Specifically, the nanofiltration concentrate water utilization treatment device is used for the pretreatment of the nanofiltration concentrate water in the desulfurized wastewater treatment system 100 of a coal-fired power plant, aiming to reduce the organic matter content therein, reduce its interference with the crystallization and precipitation of CaSO4, and thus improve the efficiency of the softening treatment of desulfurized wastewater.

[0052] It can be seen from Figure 6 that the high concentration of COD in the nanofiltration concentrate water will inhibit the formation of CaSO4 crystals in the softening of desulfurized wastewater, and as the concentration of Ca 2+ increases (from 800 mg / L to 2800 mg / L), the inhibitory effect of organic matter on the crystallization of CaSO4 becomes more obvious.

[0053] The ozone oxidation unit 1 is connected to the desulfurized wastewater treatment system 100, and obtains the nanofiltration concentrate water with high SO4 2- and high COD from its nanofiltration membrane concentrate water outlet, and conducts ozone oxidation treatment. The ozone oxidation unit 1 utilizes the strong oxidizing property of ozone to remove the molecular structure of organic matter (including humic acid, protein, etc.) in the nanofiltration concentrate water, improve its biodegradability, and reduce its inhibitory effect on the crystallization and precipitation of CaSO4.

[0054] Ozone (O3) can degrade organic matter by direct oxidation or hydroxyl radical (·OH) oxidation. The main degradation targets include refractory substances such as humic acid and long-chain organic matter, decomposing them into small-molecule organic matter or intermediate products, and improving the efficiency of subsequent biological activated carbon adsorption and degradation.

[0055] The biological activated carbon filter column 2 is connected to the ozone oxidation unit 1, receives the nanofiltration concentrate water after ozone oxidation treatment, and further removes the remaining organic matter. The biological activated carbon filter column 2 utilizes the adsorption and microbial degradation capabilities of biological activated carbon to further remove small-molecule organic matter, reduce COD accumulation, and ensure that the refluxed nanofiltration concentrate water will not affect the precipitation of CaSO4.

[0056] The small-molecule organic matter after ozone oxidation can be strongly adsorbed by biological activated carbon, and then the microorganisms attached to the surface of the activated carbon will degrade these organic matter. At the same time, ozone increases the dissolved oxygen concentration in the water, promotes the growth of aerobic microorganisms, and improves the degradation efficiency.

[0057] The reflux pipeline 3 is connected to the biological activated carbon filter column 2 and the desulfurized wastewater treatment system 100, and is used to transport the treated nanofiltration concentrate water and return it to the regulating tank or softening tank of the desulfurized wastewater treatment system 100. The reflux pipeline 3 transports the nanofiltration concentrate water after the removal of organic matter to the desulfurized wastewater treatment system 100 to ensure that the SO4 2- can be used for the crystallization and precipitation of CaSO4 to improve the softening efficiency of desulfurized wastewater; after removing COD, the nanofiltration concentrate water no longer interferes with the Ca 2+ and SO4 2- reaction, making the crystal form of CaSO4 change from plate-like to needle-like and increasing the number of crystals; at the same time, the dosage of lime milk (Ca(OH)2) and Na2CO3 in the softening process is reduced, and the operation cost of the system is lowered.

[0058] In one embodiment, after ozone oxidation, the COD of the nanofiltration concentrate water is reduced from 3400 mg / L to about 2500 mg / L, and the biodegradability of the organic matter is significantly improved, and the UV 254 decreases, indicating that aromatic organic matter is partially degraded, where UV 254 refers to the ultraviolet absorbance at a wavelength of 254 nm, which indirectly reflects the content of organic matter in water. After the removal of organic matter by the biological activated carbon, the COD is further reduced from 2500 mg / L to 1120 mg / L, and the removal rate reaches 67%.

[0059] Figure 3 is a schematic diagram of the treatment process of the nanofiltration concentrate water utilization treatment device provided by an embodiment of the present application. As Figure 3 shown, the ozone oxidation unit 1 includes: an ozone generator 11, a flow meter 12, and an ozone oxidation device 13;

[0060] The ozone generator 11 is used to generate ozone;

[0061] The flow meter 12 is connected to the ozone generator 11 and the ozone oxidation device 13, and is used to measure and control the dosage of ozone;

[0062] The ozone oxidation device 13 is connected to the desulfurized wastewater treatment system 100, and is used to make the nanofiltration concentrate water from the desulfurized wastewater treatment system 100 react fully with ozone.

[0063] Specifically, the ozone generator 11 is used to generate high-concentration ozone (O3), which is added as an oxidant to the nanofiltration concentrate to decompose the organic matter therein. The flowmeter 12 is connected to the ozone generator 11 and the ozone oxidation device 13, and is used to measure and control the dosage of ozone, ensuring the stability and efficiency of the oxidation reaction. According to parameters such as the COD concentration, flow rate, and pH value of the nanofiltration concentrate, the ozone dosage is automatically adjusted to achieve precise oxidation. The ozone oxidation device 13 is connected to the desulfurization wastewater treatment system 100, and is used to make the nanofiltration concentrate from the desulfurization wastewater treatment system 100 fully contact and react with ozone, decompose the organic matter, and improve the biodegradability. Ozone oxidation can decompose organic matter through two mechanisms: direct oxidation and hydroxyl radical (·OH) oxidation. The main degradation targets include humic acid, long-chain organic matter, protein pollutants, and aromatic compounds, etc. The content of organic matter in the treated nanofiltration concentrate is greatly reduced, creating good conditions for biological activated carbon treatment.

[0064] The specific treatment process of the ozone oxidation unit 1 is as follows: The nanofiltration concentrate is transported from the nanofiltration concentrate outlet of the desulfurization wastewater treatment system 100 to the ozone oxidation device 13. The ozone generator 11 generates high-concentration ozone, and the dosage is measured and controlled by the flowmeter 12. The ozone fully contacts the nanofiltration concentrate, directly or indirectly oxidizes the organic matter, improves the biodegradability of the nanofiltration concentrate. After the reaction, part of the organic matter is degraded into CO2 and H2O, and part is converted into small-molecule organic matter. After the oxidation treatment, the COD concentration of the nanofiltration concentrate decreases, and it enters the biological activated carbon filter column 2 for further removal of organic matter.

[0065] In one embodiment, the ozone generator 11 uses the corona discharge method or the ultraviolet light method to generate ozone, and the ozone concentration is adjustable. Through the action of a high-voltage electric field or ultraviolet light of a specific wavelength, oxygen (O2) is cracked and recombined into ozone (O3).

[0066] In one embodiment, the flowmeter 12 uses a mass flowmeter 12 (MFC) or a rotameter 12 to real-time monitor the flow rate and concentration of ozone, and feedback signals to the control system or on-line detection sensors to adjust the working state of the ozone generator 11 and maintain a stable ozone supply.

[0067] Figure 4 is a schematic structural diagram of the biological activated carbon filter column 2 provided by an embodiment of the present application, as Figure 4 shown, the biological activated carbon filter column 2 includes: a filter column housing 21, a rectifying plate 23, a supporting layer 24, and a filter material layer 25;

[0068] The nanofiltration concentrate after ozone oxidation treatment is introduced through a water inlet pipe 22 provided at the bottom surface of the filter column housing 21;

[0069] The rectifying plate 23, the supporting layer 24, and the filter material layer 25 are sequentially arranged in the filter column housing 21 from bottom to top;

[0070] The rectifying plate 23 is used to make the nanofiltration concentrated water entering from the bottom surface of the filter column housing 21 flow uniformly upward so that it can fully contact the filter media layer 25;

[0071] The supporting layer 24 is used to support the filter media layer 25 to prevent the filter media from flowing away with the water flow;

[0072] The filter media layer 25 is used to remove organic matters in the nanofiltration concentrated water through physical adsorption and microbial degradation; the nanofiltration concentrated water after the organic matter removal treatment is discharged through a water outlet pipe 26 on one side of the filter column housing 21 above the filter media layer 25.

[0073] Specifically, the filter column housing 21, as the main structure of the filter column, accommodates all internal components and provides a stable water flow channel, with the characteristics of being pressure-resistant, corrosion-resistant and wear-resistant, and is suitable for long-term operation. The inside of the filter column housing 21 adopts an up-flow fixed-bed design to ensure that the water flow enters from the bottom and passes through the filter media layer 25 from bottom to top, improving the contact efficiency. Its inner wall is smooth, which can reduce the attachment of biofilms and avoid blockage.

[0074] The water inlet pipe 22 is arranged on the bottom surface of the filter column housing 21 and is used to introduce the nanofiltration concentrated water after ozone oxidation treatment. Through the bottom water inlet method, the water flow rises uniformly, fully contacts the filter media, avoids the phenomenon of water flow short circuit, and improves the removal efficiency. The rectifying plate 23 is located above the water inlet pipe 22 and, as a water flow distribution device, can evenly distribute the water flow, prevent the water flow from directly flushing the filter media, causing local short flow or too fast flow rate, and at the same time extend the water-filter media contact time to ensure the full adsorption and degradation of organic matters. The supporting layer 24 is located above the rectifying plate 23 and, as a supporting layer for the filter media, can prevent the filter media from flowing away, ensure the smooth water flow through the filter media layer 25 without taking away the granular activated carbon, and at the same time evenly distribute the water flow to further optimize the water-filter media contact mode.

[0075] The filter media layer 25 is located above the supporting layer 24 and is a biological activated carbon layer, which is the core treatment unit of the filter column. Through the high specific surface area and pore structure of the activated carbon, it can quickly adsorb the dissolved organic matters in the water, such as small molecule humic acid, phenolic compounds, etc. The microorganisms on the filter medium use the dissolved organic matters as nutrient sources and can degrade the organic matters, improving the removal efficiency. The microorganisms can continuously degrade the attached organic matters. Under the condition of high salt concentration, a large number of salt-tolerant aerobic microorganisms growing and reproducing in the activated carbon filter column adsorb and degrade small molecule organic matters, making the interaction between the microorganisms and the activated carbon promote each other to form a relatively balanced state and extend the service life of the activated carbon.

[0076] An outlet pipe 26 is located on one side of the filter column housing 21 above the filter media layer 25 and is used to discharge the treated nanofiltration concentrate. This water is transported to the regulating tank or softening tank of the desulfurization wastewater treatment system 100, thereby increasing the CaSO4 crystallization rate and maintaining a stable effluent flow rate, thereby preventing problems such as water accumulation within the filter column and uneven flow rates.

[0077] The specific treatment process of the biological activated carbon filter column 2 is as follows: the nanofiltration concentrate, treated by the ozone oxidation unit 1, enters the bottom of the filter column through the inlet pipe 22. The rectifying plate 23 evenly directs the water flow to the support layer 24, ensuring that the water does not short-circuit. The nanofiltration concentrate flows upward through the activated carbon layer, adsorbing and degrading small organic molecules. Microorganisms further degrade the organic matter in the water, improving treatment efficiency. The treated low-COD nanofiltration concentrate is discharged through the outlet pipe 26 and returned to the desulfurization wastewater treatment system 100.

[0078] In one embodiment, the filter column housing 21 is made of stainless steel, corrosion-resistant fiberglass reinforced plastic (FRP) or high-density polyethylene (HDPE) to ensure resistance to high-salt and high-corrosion environments.

[0079] In one embodiment, the rectifying plate 23 is made of corrosion-resistant material, such as PVC, ABS or stainless steel, and has good water flow dispersion capability.

[0080] In one embodiment, salt-tolerant aerobic microorganisms are used, mainly aerobic bacteria such as Pseudomonas and Bacillus, which are adapted to high salinity environments (such as Na + 、Cl - wait).

[0081] In one embodiment, the water outlet pipe 26 is equipped with a control valve to adjust the water flow rate to match the system processing requirements.

[0082] In one embodiment, the filter material layer 25 includes granular biological activated carbon; and the supporting layer 24 includes quartz sand.

[0083] Specifically, quartz sand has the characteristics of high strength and non-decomposability, making it suitable as a filter material support. The iodine adsorption value of granular biological activated carbon is above 1000 mg / g, and the specific surface area is >900m 2 / g. Its particle size can be 8 to 16 meshes, ensuring smooth water flow and not easy to clog.

[0084] In one embodiment, if Figure 4 As shown, the biological activated carbon filter column 2 further includes: a backwash water inlet pipe 27;

[0085] The backwash water inlet pipe 27 is provided at the top of the filter column housing 21 and is used to regularly backwash the biological activated carbon filter column 2 through the backwash water inlet pipe 27 to prevent filter material from being blocked.

[0086] Specifically, during the long-term operation of the biological activated carbon filter column 2 provided in the present application, the filter media layer 25 may be blocked, the flow rate may decrease, and the treatment efficiency may decline due to reasons such as particulate deposition, excessive growth of biofilm, and accumulation of pollutants. Therefore, regular backwashing is a key measure to maintain the efficient and stable operation of the filter column.

[0087] The backwashing water inlet pipe 27 is located at the top of the filter column housing 21 and is used to transport backwashing water into the filter column. The filter media layer 25 is flushed downward through the backwashing water inlet pipe 27 to remove blockages such as suspended particles, organic matter deposits, and microbial growths on the surface of the activated carbon. At the same time, the filter media is agitated to prevent the granular activated carbon from caking and improve the adsorption efficiency.

[0088] In one embodiment, when backwashing the biological activated carbon filter column 2, the water inlet pipe 22 is used to discharge the backwashing wastewater.

[0089] Specifically, the water inlet pipe 22 is located at the bottom of the filter column housing 21 and serves as the water inlet pipe in the normal working mode and as the backwashing outlet pipe in the backwashing mode. During the backwashing process, the water inlet pipe 22 at the bottom of the filter column is converted into the backwashing outlet pipe to discharge the wastewater entrained with pollutants, ensuring that the dirt is discharged with the water flow and preventing secondary pollution of the filter media.

[0090] The backwashing water inlet pipe 27 and the backwashing outlet pipe (water inlet pipe) form an efficient backwashing system. Through this system, the blockages on the surface and in the pores of the filter media can be effectively removed, ensuring the long-term efficient operation of the filter column.

[0091] The backwashing process includes: closing the normal water inlet pipe 22 and stopping the nanofiltration concentrated water treatment process. A large flow of backwashing water is introduced through the top backwashing water inlet pipe 27 to scour the activated carbon layer to remove the biofilm, clear the microbial accumulation, remove the blocked suspended particles and deposits, and improve the adsorption capacity of the activated carbon. The backwashing outlet pipe discharges the backwashing wastewater entrained with pollutants. The backwashing lasts for 10 - 20 minutes until the water discharged from the backwashing outlet pipe becomes clear. The discharged wastewater can be sent to the sludge treatment system or the sewage treatment station to avoid secondary pollution. Finally, close the top backwashing water inlet pipe 27 and reopen the bottom water inlet pipe 22 to resume the normal nanofiltration concentrated water treatment process.

[0092] In one embodiment, single-flow backwashing or air-water combined backwashing is adopted. The single-flow backwashing uses a large flow of low-pressure water to wash the dirt on the surface of the activated carbon. The air-water combined backwashing first introduces compressed air to expand the activated carbon layer to loosen its particles, and then water is introduced for washing to improve the cleaning effect.

[0093] In one embodiment, as Figure 4 shown, the biological activated carbon filter column 2 further includes: a saturated carbon pipeline 28;

[0094] The saturated carbon pipe 28 is arranged on one side of the filter column housing 21 at the filter material layer 25 for regularly discharging the filter material with saturated adsorption capacity.

[0095] Specifically, the biological activated carbon filter column 2 uses the synergistic effect of physical adsorption + microbial degradation to remove organic matter in the nanofiltration concentrate. However, after long-term operation, the adsorption capacity of the activated carbon will gradually decay, resulting in a decrease in treatment efficiency and a reduction in the COD removal rate of the effluent. Therefore, it is necessary to regularly replace or regenerate the saturated activated carbon filter material to ensure the continuous and efficient operation of the filter column.

[0096] To achieve this purpose, the biological activated carbon filter column 2 is specially designed with a saturated carbon pipe 28, which allows the operator to conveniently discharge the adsorbed saturated activated carbon and supplement new activated carbon filter material, improving the maintainability and long-term stability of the system.

[0097] The saturated carbon pipe 28 is arranged on one side of the filter column housing 21, close to the filter material layer 25, facilitating the regular discharge of the adsorbed saturated activated carbon without disassembling the entire filter column. The saturated carbon pipe 28 can discharge the adsorbed saturated activated carbon, avoid the decline of adsorption efficiency, maintain the activity of the filter layer, ensure the stability of the COD removal capacity of the system for the nanofiltration concentrate, optimize the operation cycle of the filter column, avoid replacing the entire filter material layer 25 only after it completely fails, and reduce the maintenance cost.

[0098] The operation process of the saturated carbon pipe 28 includes: judging whether the activated carbon is saturated through indicators such as COD removal rate, UV 254 monitoring, flow rate change, etc.; if the activated carbon is saturated, close the inlet and outlet valves to prevent untreated water from entering the system; open the saturated carbon pipe 28, and discharge the saturated activated carbon from the filter column by gravity or air flow boosting, or use reverse water flow flushing to make the activated carbon suspended and flow out from the saturated carbon pipe 28 to improve the cleaning efficiency; add fresh granular activated carbon through the top filling port or special carbon supplement port to ensure uniform filling so as not to affect the water flow distribution of the filter layer; close the saturated carbon pipe 28 and reopen the inlet and outlet valves.

[0099] In an embodiment, as Figure 3 shown, the nanofiltration concentrate utilization treatment device further includes: a peristaltic pump 4;

[0100] The peristaltic pump 4 is arranged between the ozone oxidation unit 1 and the biological activated carbon filter column 2 for controlling the flow rate of the nanofiltration concentrate after ozone oxidation treatment entering the biological activated carbon filter column 2.

[0101] Specifically, the peristaltic pump 4 is used to precisely control the flow rate of the nanofiltration concentrated water, ensuring that it enters the biological activated carbon filter column 2 at a stable speed; avoiding water flow fluctuations, protecting the filtration uniformity of the activated carbon layer, and improving the organic matter removal efficiency; preventing the blockage of the activated carbon filter column, and reducing the pressure difference accumulation in the filter media layer 25 by maintaining a stable flow rate. The peristaltic pump 4 can achieve fine flow regulation by adjusting the rotation speed to ensure the stable entry of the nanofiltration concentrated water into the biological activated carbon filter column 2; it uses high salt-resistant, acid- and alkali-resistant hose materials to adapt to the desulfurization wastewater treatment environment.

[0102] In one embodiment, as Figure 3 shown, the nanofiltration concentrated water resource utilization treatment device further includes: an adjustment tank 5;

[0103] The adjustment tank 5 is arranged between the biological activated carbon filter column 2 and the reflux pipeline 3, and is used to store the nanofiltration concentrated water after the organic matter removal treatment and control the flow rate of its reflux to the desulfurization wastewater treatment system 100.

[0104] Specifically, the adjustment tank 5 is used to store the nanofiltration concentrated water with removed organic matter in the short term, avoiding the unstable operation of the treatment system due to flow rate fluctuations; balancing the water volume, adjusting the reflux rate, and preventing excessive reflux from affecting the balance of the desulfurization wastewater softening system; optimizing the CaSO4 precipitation process to ensure that calcium sulfate forms a precipitate under suitable concentration conditions and improve the softening efficiency. Through storage and buffering, the impact of short-term flow rate fluctuations on the entire desulfurization wastewater treatment process is avoided. By controlling the reflux concentration, the reaction conditions of Ca 2+ and SO4 2- are optimized to prevent scaling due to supersaturation precipitation in the softening system. Since the flow rate and water quality of the returned water are more stable, the dosing amounts of lime milk (Ca(OH)2) or Na2CO3 can be more accurate, reducing the consumption cost of chemical agents.

[0105] In one embodiment, 2 L of nanofiltration concentrated water is taken and treated in an ozone oxidation device with an ozone flux of 10 g / (L·min) for 30 minutes, and then the ozone generator is turned off after ozone oxidation. The ozone-treated water is introduced into the biological activated carbon filter column (activated carbon parameters: 8 - 16 mesh, iodine adsorption value 1000) through a peristaltic pump (rotation speed 8 r / min). The empty bed residence time gradients are set as: 0 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, and the COD, UV 254 and calcium sulfate concentration at each time point are measured respectively. The experimental results are shown in Table 1.

[0106] Table 1

[0107]

[0108] As Figure 7 and Figure 8As shown in the figure, the initial COD value is 3400 mg / L, which drops to 1120 mg / L after 30 minutes, with a removal rate of 67%. The removal trend decreases significantly with the extension of residence time, with the removal rate reaching 26% in the first 5 minutes and slowing down after 20 minutes. 254 Initial value: 6.65 → dropped to 2.215 after 30 minutes, a decrease of 66.7%, which was synchronized with the decrease in COD, indicating that aromatic organic matter and hydrophobic pollutants were effectively degraded. Figure 9 It can be seen that COD and UV 254 Significantly reduced.

[0109] Depend on Figure 10 It can be seen that the nanofiltration concentrate resource utilization treatment device provided in this application only effectively reduces the concentration of organic matter in the concentrate, while having almost no effect on the sulfate concentration. Therefore, using this method, only a very small amount of water needs to be treated (compared to the total amount of desulfurization wastewater). The treated nanofiltration concentrate is then returned to the desulfurization wastewater treatment system, which can enhance the precipitation of CaSO4 crystals while reducing the addition of lime milk and Na2CO3 in the softening system.

[0110] Analysis of the morphology of calcium sulfate crystals showed that when COD was not effectively removed, the number of crystals was small and the structure was plate-like, which may be due to the interference of organic matter that inhibited crystal growth; after COD was effectively removed, the number of crystals increased significantly and the morphology turned into needle-shaped, indicating that the removal of organic matter can optimize the crystallization environment and promote the crystallization precipitation of calcium sulfate.

[0111] In summary, ozone oxidation significantly removes refractory organic matter, and biological activated carbon further removes pollutants (COD and UV) through the synergistic effect of adsorption and biodegradation. 254 The removal rate exceeded 65%. COD removal changed the morphology of calcium sulfate crystals (plate-like → needle-like) and increased the number of crystals, proving that organic matter is the key factor in inhibiting calcium sulfate crystallization.

[0112] The present application provides a nanofiltration concentrated water resource utilization treatment device, which includes: an ozone oxidation unit, a biological activated carbon filter column and a reflux pipeline; the ozone oxidation unit is connected to a desulfurization wastewater treatment system, and is used to perform ozone oxidation treatment on the nanofiltration concentrated water from the desulfurization wastewater treatment system; the biological activated carbon filter column is connected to the ozone oxidation unit, and is used to use biological activated carbon to remove organic matter from the nanofiltration concentrated water after ozone oxidation treatment; the reflux pipeline is connected to the biological activated carbon filter column and the desulfurization wastewater treatment system, and is used to return the nanofiltration concentrated water after organic matter removal treatment to the desulfurization wastewater treatment system to enhance the crystallization and precipitation of calcium sulfate. The nanofiltration concentrated water resource utilization treatment device and method provided in the present application achieve effective treatment of nanofiltration concentrated water, improve the removal efficiency of desulfurization wastewater hardness, and achieve resource utilization of nanofiltration concentrated water and energy conservation and emission reduction of the system.

[0113] Among them, the ozone oxidation unit efficiently decomposes refractory organic matters in the nanofiltration concentrate through ozone oxidation, reduces the COD and improves the biodegradability of the wastewater; the biological activated carbon filter column utilizes the synergistic effect of activated carbon adsorption and microbial degradation to deeply remove the residual dissolved organic matters and trace pollutants after ozone treatment; the reflux pipeline optimizes the calcium sulfate supersaturation environment by returning the treated water with low organic matter and high ion concentration to the desulfurization system, and strengthens the crystallization efficiency to reduce the scaling risk.

[0114] In addition, the present application also provides a method for the resource utilization treatment of nanofiltration concentrate. By using the nanofiltration concentrate resource utilization treatment device described in the above embodiments, the resource utilization treatment of nanofiltration concentrate is completed.

[0115] Figure 5 is a schematic flow chart of the method for the resource utilization treatment of nanofiltration concentrate provided by an embodiment of the present application. As Figure 5 shown, the method for the resource utilization treatment of nanofiltration concentrate provided by the present application includes:

[0116] S501: The ozone oxidation unit performs ozone oxidation treatment on the nanofiltration concentrate from the desulfurization wastewater treatment system;

[0117] S502: The biological activated carbon filter column uses biological activated carbon to remove organic matters from the nanofiltration concentrate after ozone oxidation treatment;

[0118] S503: The reflux pipeline returns the nanofiltration concentrate after organic matter removal treatment to the desulfurization wastewater treatment system to strengthen the crystallization precipitation of calcium sulfate.

[0119] Specifically, the nanofiltration concentrate resource utilization treatment device is used for the pretreatment of the nanofiltration concentrate in the desulfurization wastewater treatment system of coal-fired power plants, aiming to reduce the organic matter content therein, reduce its interference with the crystallization precipitation of CaSO4, and thus improve the efficiency of the softening treatment of desulfurization wastewater.

[0120] The ozone oxidation unit is connected to the desulfurization wastewater treatment system, and obtains the nanofiltration concentrate with high SO4 2- and high COD from its nanofiltration membrane concentrate outlet, and performs ozone oxidation treatment. The ozone oxidation unit utilizes the strong oxidizing property of ozone to remove the molecular structures of organic matters (including humic acid, protein, etc.) in the nanofiltration concentrate, improve its biodegradability, and reduce its inhibitory effect on the crystallization precipitation of CaSO4.

[0121] Ozone (O3) can degrade organic matters by direct oxidation or hydroxyl radical (·OH) oxidation. The main degradation targets include refractory substances such as humic acid and long-chain organic matters, decomposing them into small molecular organic matters or intermediate products, and improving the efficiency of subsequent biological activated carbon adsorption and degradation.

[0122] The biological activated carbon filter column is connected to the ozone oxidation unit, receives the nanofiltration concentrate water that has been treated by ozone oxidation, and further removes the remaining organic matter. The biological activated carbon filter column utilizes the adsorption and microbial degradation capabilities of biological activated carbon to further remove small-molecule organic matter, reduce COD accumulation, and ensure that the recycled nanofiltration concentrate water does not affect the precipitation of CaSO4.

[0123] The small-molecule organic matter after ozone oxidation can be strongly adsorbed by biological activated carbon, and then the microorganisms attached to the surface of the activated carbon will degrade these organic matter. At the same time, ozone increases the dissolved oxygen concentration in the water, promotes the growth of aerobic microorganisms, and improves the degradation efficiency.

[0124] The reflux pipeline is connected to the biological activated carbon filter column and the desulfurized wastewater treatment system, used to transport the treated nanofiltration concentrate water and return it to the regulating tank or softening tank of the desulfurized wastewater treatment system. The reflux pipeline transports the nanofiltration concentrate water after organic matter removal treatment to the desulfurized wastewater treatment system to ensure that the SO4 2- can be used for the crystallization and precipitation of CaSO4, improving the softening efficiency of desulfurized wastewater; after removing COD, the nanofiltration concentrate water no longer interferes with the Ca 2+ and SO4 2- reaction, making the crystal form of CaSO4 change from plate-like to needle-like and increasing the number of crystals; at the same time, it reduces the dosage of lime milk (Ca(OH)2) and Na2CO3 during the softening process, reducing the operating cost of the system.

[0125] The present application provides a method for the resource utilization treatment of nanofiltration concentrate water. The nanofiltration concentrate water from the desulfurized wastewater treatment system is treated by ozone oxidation through the ozone oxidation unit; the biological activated carbon filter column uses biological activated carbon to remove organic matter from the nanofiltration concentrate water after ozone oxidation treatment; the reflux pipeline returns the nanofiltration concentrate water after organic matter removal treatment to the desulfurized wastewater treatment system to strengthen the crystallization and precipitation of calcium sulfate, effectively treating the nanofiltration concentrate water, improving the removal efficiency of the hardness of desulfurized wastewater, realizing the resource utilization of nanofiltration concentrate water and the energy conservation and emission reduction of the system.

[0126] Among them, the ozone oxidation unit efficiently decomposes the refractory organic matter in the nanofiltration concentrate water through ozone oxidation, reduces COD and improves the biodegradability of the wastewater; the biological activated carbon filter column utilizes the synergistic effect of activated carbon adsorption and microbial degradation to deeply remove the residual dissolved organic matter and trace pollutants after ozone treatment; the reflux pipeline optimizes the calcium sulfate supersaturation environment by returning the treated water with low organic matter and high ion concentration to the desulfurization system, strengthening the crystallization efficiency to reduce the scaling risk.

[0127] In the description of this specification, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to this application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0128] The description referring to terms such as "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. The order of the steps involved in each embodiment is used to schematically illustrate the implementation of this application, and the order of the steps is not limited and can be adjusted appropriately as needed.

[0129] In the description of this application, it should be noted that unless otherwise clearly specified and defined, the terms "install", "connect", and "couple" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood through specific circumstances.

[0130] The above-described specific embodiments have further elaborated on the purpose, technical solutions, and beneficial effects of this application. It should be understood that the above are only specific embodiments of this application and are not used to limit the protection scope of this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application should be included in the protection scope of this application.

Claims

1. A treatment device for the utilization and treatment of nanofiltration concentrated water resources, characterized in that Comprising: An ozone oxidation unit, a biological activated carbon filter column, and a reflux pipeline; The ozone oxidation unit is connected to a desulfurization wastewater treatment system for ozone oxidation treatment of the nanofiltration concentrate from the desulfurization wastewater treatment system; The biological activated carbon filter column is connected to the ozone oxidation unit for removing organic matter from the nanofiltration concentrate after ozone oxidation treatment by using biological activated carbon; the organic matter removal treatment includes physical adsorption treatment and enhanced degradation treatment of the nanofiltration concentrate after ozone oxidation treatment by biological activated carbon and aerobic microorganisms attached to its surface; The reflux pipeline is connected to the biological activated carbon filter column and the desulfurization wastewater treatment system for refluxing the nanofiltration concentrate after organic matter removal treatment to the desulfurization wastewater treatment system to enhance the crystallization and precipitation of calcium sulfate.

2. The nanofiltration concentrated water resource utilization treatment device according to claim 1, wherein The ozone oxidation unit includes: an ozone generator, a flowmeter, and an ozone oxidation device; The ozone generator is used to generate ozone; The flowmeter is connected to the ozone generator and the ozone oxidation device for measuring and controlling the dosage of ozone; The ozone oxidation device is connected to the desulfurization wastewater treatment system for enabling the nanofiltration concentrate from the desulfurization wastewater treatment system to fully react with ozone.

3. The nanofiltration concentrated water resource utilization treatment device according to claim 1, characterized in that The biological activated carbon filter column includes: a filter column housing, a rectifying plate, a supporting layer, and a filter media layer; The nanofiltration concentrate after ozone oxidation treatment is introduced through a water inlet pipe provided at the bottom surface of the filter column housing; The rectifying plate, the supporting layer, and the filter media layer are sequentially arranged in the filter column housing from bottom to top; The rectifying plate is used to evenly flow the nanofiltration concentrate entering from the bottom surface of the filter column housing upward to make it fully contact with the filter media layer; The supporting layer is used to support the filter media layer to prevent the filter media from flowing away with the water flow; The filter media layer is used to remove organic matter from the nanofiltration concentrate through physical adsorption and microbial degradation; the nanofiltration concentrate after organic matter removal treatment is discharged through a water outlet pipe on one side of the filter column housing provided above the filter media layer.

4. The nanofiltration concentrated water resource utilization treatment device according to claim 3, wherein, The biological activated carbon filter column further includes: a backwashing water inlet pipe; The backwashing water inlet pipe is provided at the top of the filter column housing for periodically backwashing the biological activated carbon filter column through the backwashing water inlet pipe to prevent the filter media from being blocked.

5. The nanofiltration concentrated water resource utilization treatment device according to claim 4, characterized in that, When backwashing the biological activated carbon filter column, the water inlet pipe is used to discharge the backwashing wastewater.

6. The nanofiltration concentrated water resource utilization treatment device according to claim 3, characterized in that The biological activated carbon filter column further includes: a saturated carbon pipeline; The saturated carbon pipeline is provided on one side of the filter column housing at the filter media layer for periodically discharging the filter media with saturated adsorption capacity.

7. The nanofiltration concentrated water resource utilization treatment device according to claim 3, characterized in that, The filter media layer includes granular biological activated carbon; the supporting layer includes quartz sand.

8. The nanofiltration concentrated water resource utilization treatment device according to claim 1, characterized in that, Further comprising: A peristaltic pump; The peristaltic pump is arranged between the ozone oxidation unit and the biological activated carbon filter column for controlling the flow rate of the nanofiltration concentrate after ozone oxidation treatment entering the biological activated carbon filter column.

9. The nanofiltration concentrated water resource utilization treatment device according to claim 1, wherein Further comprising: A regulating tank; The regulating tank is arranged between the biological activated carbon filter column and the reflux pipeline for storing the nanofiltration concentrate after organic matter removal treatment and controlling its flow rate for refluxing to the desulfurization wastewater treatment system.

10. A method for the utilization and treatment of reverse osmosis concentrate water resources, which is applied to the reverse osmosis concentrate water resources utilization and treatment device described in any one of claims 1-9, and is characterized in that, Comprising: The ozone oxidation unit performs ozone oxidation treatment on the nanofiltration concentrate from the desulfurization wastewater treatment system; The biological activated carbon filter column uses biological activated carbon to remove organic matter from the nanofiltration concentrate after ozone oxidation treatment; The reflux pipeline returns the nanofiltration concentrate after the organic matter removal treatment to the desulfurization wastewater treatment system to enhance the crystallization and precipitation of calcium sulfate.

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