A urea hydrolysis wastewater resourceful treatment system and method

Abstract

The present application relates to a kind of urea hydrolysis wastewater resource processing system and method, including sequentially connected urea pretreatment device, integrated reaction device, ultrafiltration device, reverse osmosis device and bipolar membrane electrodialysis device and with integrated reaction device connection ammonia gas processing device, integrated reaction device includes the communication reaction zone and adjustment area, adjustment area is communicated with the acid liquid outlet of bipolar membrane electrodialysis device, reaction zone is communicated with the alkali outlet of bipolar membrane electrodialysis device, by the acid liquid and alkali generated by bipolar membrane electrodialysis and integrated reaction device cooperation reuse, can not be repeatedly added acid and added alkali in the system operation process, effectively save operating cost and manpower cost, and ammonia gas enters ammonia gas processing device while can realize the recycling of ammonia gas through reaction zone.Therefore, the present application realizes the rational utilization of wastewater resource, effectively saves resource and cost, and no other waste and secondary wastewater is generated in the treatment process, and nitrogen fertilizer is additionally generated, maximum degree realizes the rational resource utilization, and does not cause secondary pollution simultaneously.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a system and method for the resource-based treatment of urea hydrolysis wastewater. Background Technology

[0002] Currently, to cope with increasingly stringent environmental regulations, most coal-fired power plants have upgraded their technology, replacing the traditional liquid ammonia with urea for denitrification. However, in actual operation, the ammonia nitrogen and salt content in the urea hydrolysis wastewater generated by the SCR denitrification system far exceeds normal standards. According to relevant environmental policies, this type of wastewater cannot meet the discharge standards for any of the pollutants. Therefore, treating urea wastewater has become a challenging problem in the wastewater treatment of coal-fired power plants.

[0003] Currently, urea-containing wastewater treatment methods include physicochemical and biological methods. However, biological treatment has relatively limited effectiveness, while traditional physicochemical methods, such as evaporation crystallization, membrane separation, and ion exchange, mostly separate salt and water from urea wastewater, failing to effectively optimize resource utilization and incurring high operating costs. Therefore, this paper proposes a urea hydrolysis wastewater resource utilization system and method to address these issues. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a urea hydrolysis wastewater resource utilization system and method, which solves the problems that the existing technology cannot effectively optimize resource utilization and has high cost when treating urea-containing wastewater.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A urea hydrolysis wastewater resource utilization treatment system includes a urea pretreatment device, an integrated reaction device, an ultrafiltration device, a reverse osmosis device, and a bipolar membrane electrodialysis device connected in sequence, as well as an ammonia treatment device connected to the integrated reaction device.

[0007] The integrated reaction device includes a reaction zone and a conditioning zone, and the reaction zone and the conditioning zone are connected.

[0008] The reaction zone is connected to the urea pretreatment device and the reaction zone is connected to the alkaline outlet of the bipolar membrane electrodialysis device. The pH value of the water sample in the reaction zone is greater than or equal to 12.

[0009] The adjustment zone is connected to the acid outlet of the bipolar membrane electrodialysis device, and the pH value of the water sample in the adjustment zone is 6.5-7.5;

[0010] The inlet of the ultrafiltration device is connected to the outlet of the neutral water sample in the conditioning zone;

[0011] The inlet of the ammonia treatment device is connected to the reaction zone.

[0012] Furthermore, the integrated reaction device is provided with a partition, which separates the integrated reaction device into a reaction zone and a regulating zone that are connected at the top. The space connected at the top of the reaction zone and the regulating zone is an overflow space, which is used to overflow the water sample from the reaction zone to the regulating zone.

[0013] Furthermore, a drain pipe and an alkali inlet are connected to the bottom of the reaction zone, and the alkali inlet is connected to the alkali outlet of the bipolar membrane electrodialysis device;

[0014] The reaction zone is equipped with a first pH meter, and the connection port between the urea pretreatment device and the reaction zone is located in the height direction between the first pH meter and the alkaline inlet.

[0015] The reaction zone is also connected to a second dosing device for replenishing the alkali solution.

[0016] Furthermore, the area at the top of the integrated reaction device corresponding to the reaction zone is connected to the ammonia treatment device via a gas pipeline;

[0017] The gas pipeline is equipped with a fan for transferring ammonia gas from the reaction zone to the ammonia gas treatment device.

[0018] The top of the integrated reaction device is conical, and the inlet of the gas pipeline is located at the tip of the cone.

[0019] Furthermore, the area at the top of the integrated reaction device corresponding to the adjustment zone is connected to the acid outlet of the bipolar membrane electrodialysis device, and the adjustment zone is equipped with a second pH meter, which is located at the connection between the adjustment zone and the ultrafiltration device.

[0020] Furthermore, the ammonia treatment device has an absorbent liquid containment chamber, which is connected to the water supply outlet of the industrial water tank and the acid outlet of the bipolar membrane electrodialysis device, so that the industrial water supply and acid are mixed to form an absorbent liquid. The outlet of the gas pipeline is located in the lower layer of the absorbent liquid containment chamber.

[0021] The absorbent container is equipped with a third pH meter, which is used to measure the pH value of the absorbent in the ammonia treatment device.

[0022] The pH value of the absorbent is 4-5.

[0023] Furthermore, the urea pretreatment device is connected to a first dosing device, which has a flocculant outlet;

[0024] The urea pretreatment unit includes a sludge outlet and a primary wastewater sample outlet.

[0025] A primary wastewater sample outlet is connected to the reaction zone of the integrated reaction device, and a first turbidity meter is provided on the outer periphery of the primary wastewater sample outlet.

[0026] Furthermore, it also includes a sludge thickening tank and a sludge dewatering machine connected in sequence;

[0027] The inlet of the sludge thickening tank is connected to the sewage pipe at the bottom of the reaction zone and the sludge outlet of the urea pretreatment device, respectively, and the inlet of the sludge dewatering machine is connected to the outlet of the sludge thickening tank.

[0028] To achieve the above objectives, the present invention also employs the following technical solution:

[0029] A method for the resource recovery treatment of urea hydrolysis wastewater, applicable to any of the urea hydrolysis wastewater resource recovery treatment systems described in the preceding paragraph, includes the following steps:

[0030] Step S1: Urea wastewater enters the urea pretreatment device from the urea hydrolysis wastewater tank for sedimentation treatment. After treatment, primary wastewater sample and sludge are generated. The primary wastewater sample enters the reaction zone, and the sludge enters the sludge thickening tank.

[0031] Step S2: Control the input amount of alkaline solution into the reaction zone of the bipolar membrane electrodialysis device, and monitor the pH value of the water sample in the reaction zone in real time.

[0032] If the pH value is ≥12, then maintain the current input volume of wastewater sample and the input volume of alkali solution.

[0033] If the pH value is not ≥12, the amount of alkaline solution input to the reaction zone of the bipolar membrane electrodialysis device shall be increased.

[0034] The high-alkalinity water sample generated in the reaction zone overflows into the adjustment zone, the ammonia gas generated enters the ammonia gas treatment device, and the impurities generated precipitate into the sludge thickening tank.

[0035] Step S3: Control the amount of acid input to the adjustment zone of the bipolar membrane electrodialysis device, and monitor the pH value of the water sample in the adjustment zone in real time.

[0036] If the pH value is between 6.5 and 7.5, then maintain the current acid input rate and neutral water sample output rate.

[0037] If the pH value is <6.5, reduce the amount of acid input to the adjustment zone of the bipolar membrane electrodialysis device, or increase the amount of high-alkaline water sample overflowing from the reaction zone to the adjustment zone, and suspend the output of neutral water sample until the pH value is 6.5-7.5;

[0038] If the pH value is >7, increase the amount of acid input to the adjustment zone of the bipolar membrane electrodialysis device, or reduce the amount of high-alkaline water sample overflowing from the reaction zone to the adjustment zone, and suspend the output of neutral water sample until the pH value is 6.5-7.5;

[0039] Step S4: The treated neutral water sample enters the ultrafiltration device, which performs ultrafiltration on the neutral water sample to obtain a secondary deionized wastewater sample, which then enters the reverse osmosis device.

[0040] Step S5: The reverse osmosis device desalinates the secondary wastewater sample by reverse osmosis to obtain high-salt wastewater and fresh water. The fresh water is reused in the fresh water plant, and the high-salt wastewater enters the bipolar membrane electrodialysis device.

[0041] Step S6: The bipolar membrane electrodialysis device converts high-salt wastewater into acid and alkali solutions. The acid solution is returned to the adjustment zone and the ammonia treatment device for reuse, and the alkali solution is returned to the reaction zone for reuse.

[0042] Furthermore, step S2 also includes:

[0043] The amount of alkaline solution input to the reaction zone of the bipolar membrane electrodialysis device is controlled, and the pH value of the water sample in the reaction zone is monitored in real time.

[0044] If the pH value is not ≥12 and the amount of alkaline solution input to the reaction zone of the bipolar membrane electrodialysis device is at its maximum value, then the second dosing device is started until the pH value of the water sample in the reaction zone is ≥12.

[0045] and / or

[0046] Step S2 further includes:

[0047] The system controls the amount of acid input to the ammonia treatment device from the bipolar membrane electrodialysis device and monitors the pH value of the absorbent in the ammonia treatment device in real time.

[0048] If the pH value is 4-5, then maintain the current acid input rate and the output rate of the industrial water tank.

[0049] If the pH value is <4, reduce the amount of acid input from the bipolar membrane electrodialysis device to the ammonia treatment device, or increase the amount of water sample taken from the industrial water tank, and suspend the ammonia input until the pH value is 4-5.

[0050] If the pH value is >5, increase the amount of acid input from the bipolar membrane electrodialysis device to the ammonia treatment device, or reduce the amount of water sample taken from the industrial water tank and suspend the ammonia input until the pH value is 4-5.

[0051] The ammonia treatment device absorbs ammonia to obtain any one or more combinations of ammonium chloride, ammonium bisulfate, and ammonium sulfate.

[0052] In summary, compared with the prior art, the present invention has at least the following beneficial effects:

[0053] The urea hydrolysis wastewater resource utilization system of the present invention includes a urea pretreatment device, an integrated reaction device, an ultrafiltration device, a reverse osmosis device, and a bipolar membrane electrodialysis device connected in sequence, and an ammonia treatment device connected to the integrated reaction device. The integrated reaction device includes a reaction zone and a conditioning zone connected in series. The conditioning zone is connected to the acid outlet of the bipolar membrane electrodialysis device, and the reaction zone is connected to the alkali outlet of the bipolar membrane electrodialysis device. By recycling the acid and alkali solutions generated by the bipolar membrane electrodialysis with the integrated reaction device, repeated addition of acid and alkali during system operation can be avoided, effectively saving operating and labor costs. Furthermore, ammonia gas can be recovered and utilized simultaneously as it enters the ammonia treatment device through the reaction zone. Therefore, the present invention achieves the rational utilization of wastewater resources, effectively saving resources and costs. Moreover, the treatment process generates no other waste or secondary wastewater while also producing additional nitrogen fertilizer, maximizing rational resource utilization without causing secondary pollution. Attached Figure Description

[0054] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0055] Figure 1 This is a schematic diagram of the urea hydrolysis wastewater resource utilization system provided in one embodiment of the present invention.

[0056] Figure 2 This is a schematic diagram of the integrated reaction device provided in one embodiment of the present invention.

[0057] Figure 3 The flowchart illustrates the urea hydrolysis wastewater resource utilization method provided by this invention.

[0058] Figure 4 A flowchart of the ammonia treatment method provided by the present invention.

[0059] Explanation of reference numerals in the attached figures:

[0060] 1. Urea pretreatment device; 11. First dosing device; 12. Primary wastewater sample pipeline; 13. First turbidity meter;

[0061] 2. Integrated reaction device; 21. Reaction zone; 211. Alkali inlet; 212. First pH meter; 213. First connecting port; 214. Second dosing device; 22. Adjustment zone; 221. Second pH meter; 222. Acid inlet; 23. Baffle; 24. Overflow space;

[0062] 3. Ultrafiltration device;

[0063] 4. Reverse osmosis unit;

[0064] 5. Bipolar membrane electrodialysis device; 51. Alkali tank; 52. Acid tank;

[0065] 6. Ammonia treatment unit; 61. Gas pipeline; 62. Fan; 63. Industrial water tank; 64. Third pH meter;

[0066] 7. Sludge thickening tank; 71. Sewage discharge pipe;

[0067] 8. Sludge dewatering machine;

[0068] 9. Urea hydrolysis wastewater pond;

[0069] 10. Freshwater tank. Detailed Implementation

[0070] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0071] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0072] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0073] As attached Figure 1 As shown, this embodiment of the invention discloses a urea hydrolysis wastewater resource utilization treatment system, including a urea pretreatment device 1, an integrated reaction device 2, an ultrafiltration device 3, a reverse osmosis device 4, and a bipolar membrane electrodialysis device 5 connected in sequence, and an ammonia treatment device 6 connected to the integrated reaction device 2.

[0074] The integrated reaction device 2 includes a reaction zone 21 and a conditioning zone 22, which are connected.

[0075] The reaction zone 21 is connected to the urea pretreatment device 1 and the alkaline outlet of the bipolar membrane electrodialysis device 5. The pH value of the water sample in the reaction zone 21 is greater than or equal to 12.

[0076] The adjustment zone 22 is connected to the acid outlet of the bipolar membrane electrodialysis device 5, and the pH value of the water sample in the adjustment zone 22 is 6.5-7.5;

[0077] The inlet of ultrafiltration device 3 is connected to the neutral water sample outlet of conditioning zone 22;

[0078] The inlet of the ammonia treatment device 6 is connected to the reaction zone 21.

[0079] Specifically, during the operation of the urea hydrolysis wastewater resource utilization system, urea-containing wastewater first enters the urea pretreatment device 1 from the urea hydrolysis wastewater tank 9 for sedimentation pretreatment, separating most impurities and sludge from the solid-liquid mixture. The treated primary wastewater sample then enters the reaction zone 21 of the integrated reaction device 2. The reaction zone 21 adjusts the pH value of the primary wastewater sample to greater than or equal to 12. At this time, under the high alkaline environment, almost all the ammonia nitrogen in the primary wastewater sample exists in the form of ammonia gas and escapes from the primary wastewater sample into the ammonia gas treatment device 6. The ammonia gas treatment device 6 converts the ammonia gas into... Nitrogen fertilizer is produced, thus realizing the resource utilization of ammonia nitrogen. On the other hand, the high-alkaline water sample enters the adjustment zone 22 through the part connected to the adjustment zone 22. The adjustment zone 22 adjusts the pH value of the high-alkaline water sample to 6.5-7.5, turning it into a neutral water sample, and then it enters the ultrafiltration device 3 for ultrafiltration. The resulting secondary wastewater sample enters the reverse osmosis device 4 for separation and concentration. The generated freshwater is collected in the freshwater tank 10 for reuse in other devices in the factory. The generated high-salinity wastewater enters the bipolar membrane electrodialysis device 5. The bipolar membrane electrodialysis device 5 can convert the salt in the high-salinity wastewater into the corresponding acid and alkali solutions without introducing new components. In this system, the acid outlet of the bipolar membrane electrodialysis device 5 is connected to the adjustment zone 22, and the alkali outlet of the bipolar membrane electrodialysis device 5 is connected to the reaction zone 21. The acid and alkali enter the adjustment zone 22 and the reaction zone 21 for reuse, eliminating the need for repeated external addition of acid and alkali during system operation, effectively saving operating and labor costs. The in-plant reuse of multiple resources such as acid, alkali, nitrogen fertilizer, and fresh water realizes the rational utilization of urea wastewater resources. Moreover, the urea hydrolysis wastewater resource utilization treatment system does not generate other waste or secondary wastewater during the treatment process, meaning that while making rational resource utilization, it will not cause secondary pollution.

[0080] In order for the integrated reaction device 2 to perform multiple operations in one unit, as shown in the attached... Figure 2 As shown, the integrated reaction device 2 is equipped with a partition 23, which separates the integrated reaction device 2 into a reaction zone 21 and a regulating zone 22 that are connected at the top. The space connected above the reaction zone 21 and the regulating zone 22 is an overflow space 24. The overflow space 24 is used to overflow the high-alkalinity water sample from the reaction zone 21 to the regulating zone 22. That is, when the water sample inside the reaction zone 21 is regulated to a value greater than or equal to 12, the high-alkalinity water sample continuously rises and flows from the overflow space 24 into the regulating zone 22, facilitating further regulation of the high-alkalinity water sample in the subsequent regulating zone 22. The design of the partition 23 allows the reactions in the reaction zone 21 and the regulating zone 22 to take place in independent spaces, avoiding mutual interference and reducing the footprint of the integrated reaction device 2.

[0081] Furthermore, the bottom of the reaction zone 21 is connected to a drain pipe 71 and an alkali inlet 211, and the alkali inlet 211 is connected to the alkali outlet of the alkali tank 51 in the bipolar membrane electrodialysis device 5; the reaction zone 21 is equipped with a first pH meter 212, and the first connection port 213 between the urea pretreatment device 1 and the reaction zone 21 is located between the first pH meter 212 and the alkali inlet 211 in the height direction. The recycled alkaline solution generated by the bipolar membrane electrodialysis unit 5 enters from the alkaline solution inlet 211 at the bottom of the reaction zone 21. It reacts fully with the primary wastewater sample entering from the urea pretreatment unit 1 above and the first connection port 213 of the reaction zone 21. To monitor the pH value of the water sample after mixing the primary wastewater sample and the alkaline solution in real time, a first pH meter 212 is installed above the first connection port 213. The first pH meter 212 is electrically connected to the system. The pH value is first monitored by the first pH meter 212 in the reaction zone 21. Then, as needed, alkaline solution is added through the alkaline solution inlet 211 for adjustment. That is, the reaction zone 21 operates normally when the measured pH value is greater than or equal to 12, and when the measured pH value is less than 12, the input of alkaline solution is increased through the alkaline solution inlet 211 to achieve the operating standard of the reaction zone 21. In addition, the sludge generated during the reaction is discharged promptly through the drain pipe 71 connected at the bottom to prevent sludge from clogging the alkaline solution inlet 211 and the first connection port 213.

[0082] In order to address the situation where the alkaline solution recycled from the bipolar membrane electrodialysis unit 5 is insufficient to adjust the pH value of the water sample in the reaction zone 21 to a value greater than or equal to 12, the reaction zone 21 is also connected to a second dosing device 214 for replenishing the alkaline solution.

[0083] When the pH value of the water sample in reaction zone 21 reaches 12 or higher, almost all the ammonia nitrogen in the highly alkaline wastewater exists as ammonia gas and escapes. It enters the ammonia treatment device 6 through the area corresponding to reaction zone 21 at the top of the integrated reaction device 2 and the connected gas pipeline 61. Furthermore, a fan 62 is installed in the gas pipeline 61 to more effectively transfer all the ammonia gas generated in reaction zone 21 to the ammonia treatment device 6. The top of the integrated reaction device 2 is conical, and the inlet of the gas pipeline 61 is located at the tip of the cone, facilitating the convergence of ammonia gas towards the tip and allowing it to flow more smoothly into the ammonia treatment device 6 through the inlet of the gas pipeline 61, thus accelerating the ammonia gas transfer speed.

[0084] The area at the top of the integrated reaction device 2 corresponding to the adjustment zone 22 is connected to the acid outlet of the acid tank 52 of the bipolar membrane electrodialysis device 5. The acid inlet 222 of the adjustment zone 22 is located at the top to mix with the high-alkaline water sample overflowing from the upper overflow space 24 as soon as possible, thereby setting the pH value of the water sample in the adjustment zone 22 to 6.5-7.5 for subsequent ultrafiltration and reverse osmosis treatment. The adjustment zone 22 is equipped with a second pH meter 221, which is located at the connection between the adjustment zone 22 and the ultrafiltration device 3, and is used to measure the pH value of the water sample at the inlet of the ultrafiltration device 3 in real time.

[0085] The ammonia treatment device 6 has an absorbent liquid containment chamber, which is connected to the water supply outlet of the industrial water tank 63 and the acid outlet of the bipolar membrane electrodialysis device 5, respectively, so that the industrial water and acid are mixed to form the absorbent liquid. The outlet of the gas pipeline 61 is located in the lower layer of the absorbent liquid containment chamber, which allows the ammonia gas entering from the reaction zone 21 to quickly contact the absorbent liquid, obtaining any one or more combinations of ammonium chloride, ammonium bisulfate, and ammonium sulfate, which can be used as nitrogen fertilizer for greening fertilization, realizing the rational utilization of ammonia nitrogen resources. The absorbent liquid containment chamber is equipped with a third pH meter 64 to measure the pH value of the absorbent liquid in the ammonia treatment device 6; the optimal pH value of the absorbent liquid is 4-5. This acidity of the absorbent liquid can continuously and effectively absorb ammonia gas and avoid unnecessary side reactions caused by excessively vigorous reactions when the acidity is too low.

[0086] The urea pretreatment device 1 is connected to a first dosing device 11, which has a flocculant outlet. Flocculants and coagulants enter the urea pretreatment device 1 through the first dosing device 11, causing suspended solids and other impurities and sludge in the urea-containing wastewater to settle, thus achieving preliminary purification of the urea-containing wastewater. The urea pretreatment device 1 also includes a sludge outlet for discharging impurities and sludge sediment. Furthermore, the urea pretreatment device 1 also includes a primary wastewater sample outlet. A primary wastewater sample pipeline 12 connects the primary wastewater sample outlet to the reaction zone 21 of the integrated reaction device 2. A first turbidity meter 13 is installed around the primary wastewater sample outlet. The turbidity of the primary wastewater sample monitored by the first turbidity meter 13 must be less than 5 NTU before it can enter the reaction zone 21 for subsequent treatment.

[0087] In order to make reasonable use of the discharged sludge, the urea hydrolysis wastewater resource treatment system also includes a sludge thickening tank 7 and a sludge dewatering machine 8 connected in sequence.

[0088] The inlet of the sludge thickening tank 7 is connected to the sewage pipe 71 at the bottom of the reaction zone 21 and the sludge outlet of the urea pretreatment device 1, respectively. The inlet of the sludge dewatering machine 8 is connected to the outlet of the sludge thickening tank 7.

[0089] Specifically, sludge enters the sludge thickening tank 7 from the urea pretreatment unit 1 and the reaction zone 21 through the sewage pipe 71 for thickening. The thickened sludge is then dewatered by the sludge dewatering machine 8. The resulting water sample is recycled to the urea hydrolysis wastewater tank 9. The sludge and coal sample are mixed and co-fired in the furnace for power supply in the plant, realizing the resource utilization of sludge and effectively reducing operating costs.

[0090] As attached Figure 3As shown, in addition to the urea hydrolysis wastewater resource utilization system described above, the present invention also provides a urea hydrolysis wastewater resource utilization method based on the operation of the urea hydrolysis wastewater resource utilization system described above. This urea hydrolysis wastewater resource utilization method corresponds to the urea hydrolysis wastewater resource utilization system embodiment described above. The urea hydrolysis wastewater resource utilization method described below can be referred to in correspondence with the urea hydrolysis wastewater resource utilization system described above.

[0091] A method for resource recovery treatment of urea hydrolysis wastewater includes the following steps:

[0092] Step S1: Urea wastewater enters urea pretreatment unit 1 from urea hydrolysis wastewater tank 9 for sedimentation treatment. After treatment, primary wastewater sample and sludge are generated. Primary wastewater sample enters reaction zone 21, and sludge enters sludge thickening tank 7.

[0093] Step S2: Control the input volume of alkaline solution into reaction zone 21 of the bipolar membrane electrodialysis device 5, and monitor the pH value of the water sample in reaction zone 21 in real time.

[0094] If the pH value is ≥12, then maintain the current input volume of wastewater sample and the input volume of alkali solution.

[0095] If the pH value is not ≥12, increase the amount of alkaline solution input to the reaction zone 21 of the bipolar membrane electrodialysis device 5;

[0096] The high-alkalinity water sample generated in reaction zone 21 overflows into adjustment zone 22, the generated ammonia enters ammonia treatment device 6, and the generated impurities precipitate into sludge thickening tank 7.

[0097] Step S3: Control the acid input volume of the bipolar membrane electrodialysis device 5 into the adjustment zone 22, and monitor the pH value of the water sample in the adjustment zone 22 in real time.

[0098] If the pH value is between 6.5 and 7.5, then maintain the current acid input rate and neutral water sample output rate.

[0099] If the pH value is <6.5, reduce the amount of acid input to the adjustment zone 22 of the bipolar membrane electrodialysis device 5, or increase the amount of high-alkaline water sample overflowing from the reaction zone 21 to the adjustment zone 22, and suspend the output of neutral water sample until the pH value is 6.5-7.5.

[0100] If the pH value is >7, increase the acid input to the adjustment zone 22 of the bipolar membrane electrodialysis device 5, or reduce the amount of high-alkaline water sample overflowing from the reaction zone 21 to the adjustment zone 22, and suspend the output of neutral water sample until the pH value is 6.5-7.5.

[0101] Step S4: The treated neutral water sample enters the ultrafiltration device 3, which performs ultrafiltration on the neutral water sample to obtain a secondary deionized wastewater sample, which then enters the reverse osmosis device 4.

[0102] Step S5: The reverse osmosis device 4 desalinates the secondary wastewater sample by reverse osmosis to obtain high-salt wastewater and fresh water. The fresh water is reused in the fresh water plant, and the high-salt wastewater enters the bipolar membrane electrodialysis device 5.

[0103] Step S6: The bipolar membrane electrodialysis device 5 converts the high-salt wastewater into acid and alkali solutions. The acid solution is returned to the adjustment zone 22 and the ammonia treatment device 6 for reuse, and the alkali solution is returned to the reaction zone 21 for reuse.

[0104] During operation, various resources such as acidic solutions, alkaline solutions, nitrogen fertilizer, and fresh water generated are reused within the factory, achieving rational and resource-efficient utilization of urea wastewater during hydrolysis and significantly reducing costs. Furthermore, the above method produces no other waste or secondary wastewater, meaning that while achieving rational resource utilization, it does not cause secondary pollution.

[0105] When the alkaline solution recycled from the bipolar membrane electrodialysis device 5 is insufficient to adjust the pH of the water sample in the reaction zone 21 to 12, step S2 further includes: controlling the amount of alkaline solution input into the reaction zone 21 from the bipolar membrane electrodialysis device 5, and detecting the pH value of the water sample in the reaction zone 21 in real time. If the pH value is not ≥12 and the amount of alkaline solution input into the reaction zone 21 from the bipolar membrane electrodialysis device 5 is at its maximum value, then the second dosing device 214 is started until the pH value of the water sample in the reaction zone 21 is ≥12.

[0106] Additionally, as attached Figure 4 As shown, step S2 also includes the treatment of ammonia gas to achieve the conversion of ammonia nitrogen: controlling the acid input of the bipolar membrane electrodialysis device 5 to the ammonia treatment device 6, and monitoring the pH value of the absorbent in the ammonia treatment device 6 in real time.

[0107] If the pH value is 4-5, then maintain the current acid input rate and the output rate of industrial water tank 63.

[0108] If the pH value is <4, reduce the amount of acid input to the ammonia treatment device 6 from the bipolar membrane electrodialysis device 5, or increase the amount of water sample taken from the industrial water tank 63, and suspend the ammonia input until the pH value is 4-5.

[0109] If the pH value is >5, increase the acid input of the bipolar membrane electrodialysis device 5 into the ammonia treatment device 6, or reduce the amount of water sample extracted from the industrial water tank 63 and suspend the ammonia input until the pH value is 4-5.

[0110] The ammonia treatment device 6 absorbs ammonia gas to obtain any one or more combinations of ammonium chloride, ammonium bisulfate, and ammonium sulfate, which can be used as nitrogen fertilizer in subsequent greening fertilization, realizing the resource-based and rational utilization of ammonia nitrogen.

[0111] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A urea hydrolysis wastewater resource utilization treatment system, characterized in that, It includes a urea pretreatment device, an integrated reaction device, an ultrafiltration device, a reverse osmosis device, and a bipolar membrane electrodialysis device connected in sequence, as well as an ammonia treatment device connected to the integrated reaction device; The integrated reaction device includes a reaction zone and a conditioning zone, and the reaction zone and the conditioning zone are connected. The reaction zone is connected to the urea pretreatment device and the reaction zone is connected to the alkaline outlet of the bipolar membrane electrodialysis device. The pH value of the water sample in the reaction zone is greater than or equal to 12. The adjustment zone is connected to the acid outlet of the bipolar membrane electrodialysis device, and the pH value of the water sample in the adjustment zone is 6.5-7.5; The inlet of the ultrafiltration device is connected to the outlet of the neutral water sample in the conditioning zone; The inlet of the ammonia treatment device is connected to the reaction zone; The integrated reaction device is equipped with a partition, which separates the integrated reaction device into a reaction zone and a regulating zone that are connected at the top. The space connected at the top of the reaction zone and the regulating zone is an overflow space, which is used to overflow the water sample from the reaction zone to the regulating zone. The bottom of the reaction zone is connected to a drain pipe and an alkali inlet, and the alkali inlet is connected to the alkali outlet of the bipolar membrane electrodialysis device. The reaction zone is equipped with a first pH meter, and the connection port between the urea pretreatment device and the reaction zone is located in the height direction between the first pH meter and the alkaline inlet. The reaction zone is also connected to a second dosing device for replenishing the alkali solution; The area at the top of the integrated reaction device corresponding to the reaction zone is connected to the ammonia treatment device via a gas pipeline. The gas pipeline is equipped with a fan for transferring ammonia gas from the reaction zone to the ammonia gas treatment device. The top of the integrated reaction device is conical, and the inlet of the gas pipeline is located at the tip of the cone; The area at the top of the integrated reaction device corresponding to the adjustment zone is connected to the acid outlet of the bipolar membrane electrodialysis device. The adjustment zone is equipped with a second pH meter, which is located at the connection between the adjustment zone and the ultrafiltration device. The ammonia treatment device has an absorbent liquid containment chamber, which is connected to the water supply outlet of the industrial water tank and the acid outlet of the bipolar membrane electrodialysis device, so that the industrial water supply and acid are mixed to form an absorbent liquid. The outlet of the gas pipeline is located in the lower layer of the absorbent liquid containment chamber.

2. The urea hydrolysis wastewater resource utilization treatment system as described in claim 1, characterized in that, The absorbent container is equipped with a third pH meter, which is used to measure the pH value of the absorbent in the ammonia treatment device. The pH value of the absorbent is 4-5.

3. The urea hydrolysis wastewater resource utilization treatment system as described in claim 1, characterized in that, The urea pretreatment device is connected to a first dosing device, which has a flocculant outlet. The urea pretreatment unit includes a sludge outlet and a primary wastewater sample outlet. A primary wastewater sample outlet is connected to the reaction zone of the integrated reaction device, and a first turbidity meter is provided on the outer periphery of the primary wastewater sample outlet.

4. The urea hydrolysis wastewater resource utilization treatment system as described in claim 1, characterized in that, It also includes a sludge thickening tank and a sludge dewatering machine connected in sequence; The inlet of the sludge thickening tank is connected to the sewage pipe at the bottom of the reaction zone and the sludge outlet of the urea pretreatment device, respectively, and the inlet of the sludge dewatering machine is connected to the outlet of the sludge thickening tank.

5. A method for resource recovery treatment of urea hydrolysis wastewater, applicable to the urea hydrolysis wastewater resource recovery treatment system described in any one of claims 1-4, characterized in that, Includes the following steps: Step S1: Urea wastewater enters the urea pretreatment device from the urea hydrolysis wastewater tank for sedimentation treatment. After treatment, primary wastewater sample and sludge are generated. The primary wastewater sample enters the reaction zone, and the sludge enters the sludge thickening tank. Step S2: Control the input amount of alkaline solution into the reaction zone of the bipolar membrane electrodialysis device, and monitor the pH value of the water sample in the reaction zone in real time. If the pH value is ≥12, then maintain the current input volume of wastewater sample and the input volume of alkali solution. If the pH value is not ≥12, the amount of alkaline solution input to the reaction zone of the bipolar membrane electrodialysis device shall be increased. The high-alkalinity water sample generated in the reaction zone overflows into the adjustment zone, the ammonia gas generated enters the ammonia gas treatment device, and the impurities generated precipitate into the sludge thickening tank. Step S3: Control the amount of acid input to the adjustment zone of the bipolar membrane electrodialysis device, and monitor the pH value of the water sample in the adjustment zone in real time. If the pH value is between 6.5 and 7.5, then maintain the current acid input rate and neutral water sample output rate. If the pH value is <6.5, reduce the amount of acid input to the adjustment zone of the bipolar membrane electrodialysis device, or increase the amount of high-alkaline water sample overflowing from the reaction zone to the adjustment zone, and suspend the output of neutral water sample until the pH value is 6.5-7.5; If the pH value is >7, increase the amount of acid input to the adjustment zone of the bipolar membrane electrodialysis device, or reduce the amount of high-alkaline water sample overflowing from the reaction zone to the adjustment zone, and suspend the output of neutral water sample until the pH value is 6.5-7.5; Step S4: The treated neutral water sample enters the ultrafiltration device, which performs ultrafiltration on the neutral water sample to obtain a secondary deionized wastewater sample, which then enters the reverse osmosis device. Step S5: The reverse osmosis device desalinates the secondary wastewater sample by reverse osmosis to obtain high-salt wastewater and fresh water. The fresh water is reused in the fresh water plant, and the high-salt wastewater enters the bipolar membrane electrodialysis device. Step S6: The bipolar membrane electrodialysis device converts high-salt wastewater into acid and alkali solutions. The acid solution is returned to the adjustment zone and the ammonia treatment device for reuse, and the alkali solution is returned to the reaction zone for reuse.

6. The method as described in claim 5, characterized in that, Step S2 further includes: The amount of alkaline solution input to the reaction zone of the bipolar membrane electrodialysis device is controlled, and the pH value of the water sample in the reaction zone is monitored in real time. If the pH value is not ≥12 and the amount of alkaline solution input to the reaction zone of the bipolar membrane electrodialysis device is at its maximum value, then the second dosing device is started until the pH value of the water sample in the reaction zone is ≥12. and / or Step S2 further includes: The system controls the amount of acid input to the ammonia treatment device from the bipolar membrane electrodialysis device and monitors the pH value of the absorbent in the ammonia treatment device in real time. If the pH value is 4-5, then maintain the current acid input rate and the output rate of the industrial water tank. If the pH value is <4, reduce the amount of acid input from the bipolar membrane electrodialysis device to the ammonia treatment device, or increase the amount of water sample taken from the industrial water tank, and suspend the ammonia input until the pH value is 4-5. If the pH value is >5, increase the amount of acid input from the bipolar membrane electrodialysis device to the ammonia treatment device, or reduce the amount of water sample taken from the industrial water tank and suspend the ammonia input until the pH value is 4-5. The ammonia treatment device absorbs ammonia to obtain any one or more combinations of ammonium chloride, ammonium bisulfate, and ammonium sulfate.

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