Resourceful treatment system and method for urea hydrolysis wastewater

Abstract

The invention relates to a urea hydrolysis wastewater resourceful treatment system and method.The urea hydrolysis wastewater resourceful treatment system comprises a urea pretreatment device, an integrated reaction device, an ultrafiltration device, a reverse osmosis device, a bipolar membrane electrodialysis device and an ammonia gas treatment device connected with the integrated reaction device, the adjusting area is communicated with an acid liquor outlet of the bipolar membrane electrodialysis device, the reaction area is communicated with an alkali liquor outlet of the bipolar membrane electrodialysis device, and acid liquor and alkali liquor generated by bipolar membrane electrodialysis are matched with the integrated reaction device for reuse, so that acid and alkali do not need to be repeatedly added in the system operation process, the operation cost and the labor cost are effectively saved, and the operation efficiency is improved. And the ammonia gas enters the ammonia gas treatment device through the reaction area, and meanwhile, the recycling of the ammonia gas can be realized. Therefore, resource reasonable utilization of the wastewater is achieved, resources and cost are effectively saved, no other waste materials and secondary wastewater are generated in the treatment process, meanwhile, nitrogen fertilizer can be additionally generated, reasonable resource utilization is achieved to the maximum extent, and meanwhile secondary pollution cannot be caused.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a urea hydrolysis wastewater resource treatment system and method. Background Art

[0002] At present, in order to cope with the increasingly severe environmental situation, coal-fired power plants have replaced the traditional liquid ammonia with urea for denitrification after upgrading their technology. However, in actual operation, the ammonia nitrogen and salt content in the urea hydrolysis wastewater produced by the SCR denitrification system far exceeds the normal standard. According to the requirements of relevant environmental protection policies, this type of wastewater cannot meet the conditions for standard discharge in terms of various pollutant indicators. Therefore, the treatment of urea wastewater has become a difficult problem in the treatment of wastewater in coal-fired power plants.

[0003] At present, the treatment methods for urea-containing wastewater include physical and chemical methods and biological treatment methods, but the treatment effect of biological treatment is relatively limited. Traditional physical and chemical methods include evaporation crystallization, membrane separation and ion exchange, etc., most of which separate the salt and water in urea wastewater, cannot effectively optimize the utilization of resources, and have high operating costs. Therefore, a urea hydrolysis wastewater resource treatment system and method are provided to solve the above problems. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a urea hydrolysis wastewater resource treatment system and method, which solves the problem that the prior art cannot effectively achieve optimal utilization of resources when treating urea-containing wastewater and has high costs.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A urea hydrolysis wastewater resource treatment system comprises 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;

[0007] The integrated reaction device comprises a reaction zone and a regulating zone, and the reaction zone and the regulating zone are in communication;

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

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

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

[0011] The inlet of the ammonia treatment device is communicated with the reaction zone.

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

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

[0014] The reaction zone is provided with a first pH meter, and the communication port between the urea pretreatment device and the reaction zone is located between the first pH meter and the alkali solution inlet in the height direction;

[0015] The reaction zone is also connected to a second dosing device for replenishing 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 through a gas pipeline;

[0017] A fan is provided in the gas pipeline for transmitting the ammonia gas in 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 regulating zone is connected to the acid outlet of the bipolar membrane electrodialysis device, and the regulating zone is provided with a second pH meter, which is located at the connection between the regulating zone and the ultrafiltration device.

[0020] Furthermore, the ammonia treatment device has an absorption liquid containing chamber inside, and the absorption liquid containing chamber is respectively connected to the water supply outlet of the industrial water pool and the acid outlet of the bipolar membrane electrodialysis device, so that the industrial water supply and the acid are mixed to form the absorption liquid, and the outlet of the gas pipeline is located at the lower layer of the absorption liquid containing chamber;

[0021] A third pH meter is provided in the absorption liquid containing chamber, and the third pH meter is used to measure the pH value of the absorption liquid in the ammonia treatment device;

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

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

[0024] The urea pretreatment device comprises a sludge outlet and a primary decontaminated water sample outlet.

[0025] A primary decontaminated water sample pipeline is connected between the primary decontaminated water sample outlet and the reaction zone of the integrated reaction device, and a first turbidity meter is arranged on the periphery of the primary decontaminated water 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 concentration tank is communicated with 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 communicated with the outlet of the sludge concentration tank.

[0028] In order to achieve the above object, the present invention also adopts the following technical solutions:

[0029] A method for resource-based treatment of urea hydrolysis wastewater, applicable to any of the urea hydrolysis wastewater resource-based treatment systems described above, comprises the following steps:

[0030] Step S1, urea wastewater enters the urea pretreatment device from the urea hydrolysis wastewater tank for sedimentation treatment, and generates a primary decontaminated water sample and sludge after treatment, the primary decontaminated water sample enters the reaction zone, and the sludge enters the sludge concentration tank;

[0031] Step S2, controlling the amount of alkali solution input into the reaction zone of the bipolar membrane electrodialysis device, and detecting the pH value of the water sample in the reaction zone in real time,

[0032] If the pH value is ≥12, the current input amount of the wastewater sample and the input amount of the alkali solution are maintained;

[0033] If the pH value is not ≥ 12, increasing the amount of alkali solution input into the reaction zone of the bipolar membrane electrodialysis device;

[0034] The high-alkali water sample produced in the reaction zone overflows into the adjustment zone, the generated ammonia enters the ammonia treatment device, and the generated impurities precipitate into the sludge concentration tank;

[0035] Step S3, controlling the amount of acid solution inputted into the regulating zone by the bipolar membrane electrodialysis device, and detecting the pH value of the water sample in the regulating zone in real time,

[0036] If the pH value is 6.5-7.5, the current acid input and neutral water sample output are maintained;

[0037] If the pH value is less than 6.5, the amount of acid solution inputted into the regulating zone by the bipolar membrane electrodialysis device is reduced, or the amount of high-alkali water sample overflowing from the reaction zone to the regulating zone is increased, and the output of neutral water sample is suspended until the pH value is 6.5-7.5;

[0038] If the pH value is greater than 7, the amount of acid solution inputted into the regulating zone by the bipolar membrane electrodialysis device is increased, or the amount of high-alkali water sample overflowing from the reaction zone to the regulating zone is reduced, and the output of neutral water sample is suspended until the pH value is 6.5-7.5;

[0039] Step S4, the treated neutral water sample enters the ultrafiltration device, the ultrafiltration device ultrafilters the neutral water sample, and the secondary decontaminated water sample enters the reverse osmosis device;

[0040] Step S5, the reverse osmosis device performs reverse osmosis desalination on the secondary decontaminated water sample to obtain high-salt wastewater and fresh water, which are 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 the high-salt wastewater into acid solution and alkali solution, 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, the step S2 further includes:

[0043] Controlling the amount of alkali solution input into the reaction zone by the bipolar membrane electrodialysis device, and detecting the pH value of the water sample in the reaction zone in real time,

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

[0045] and / or

[0046] The step S2 further comprises:

[0047] Controlling the amount of acid solution input from the bipolar membrane electrodialysis device to the ammonia treatment device, and monitoring the pH value of the absorption liquid in the ammonia treatment device in real time,

[0048] If the pH value = 4-5 is met, the current acid input and industrial pool water sample output are maintained;

[0049] If the pH value is less than 4, the amount of acid solution input from the bipolar membrane electrodialysis device to the ammonia treatment device is reduced, or the amount of water sample extracted from the industrial water pool is increased, and the entry of ammonia is suspended until the pH value is 4-5;

[0050] If the pH value is greater than 5, the amount of acid solution input from the bipolar membrane electrodialysis device to the ammonia treatment device is increased, or the amount of water sample extracted from the industrial water pool is reduced, and the entry of ammonia is suspended 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 treatment system of the present invention comprises 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, wherein the integrated reaction device comprises a connected reaction zone and a regulating zone, wherein the regulating 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, and the acid and alkali produced by the bipolar membrane electrodialysis are combined with the integrated reaction device for reuse, so that it is not necessary to repeatedly add acid and alkali during the operation of the system, and the operation cost and manpower cost are effectively saved, and ammonia enters the ammonia treatment device through the reaction zone and can realize the recycling of ammonia at the same time. Therefore, the present invention realizes the resource utilization of wastewater, effectively saves resources and costs, and can generate nitrogen fertilizer additionally while no other waste materials and secondary wastewater are produced during the treatment process, and realizes reasonable resource utilization to the greatest extent without causing secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

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

[0057] Figure 3 The present invention provides a flow chart of the method for resource treatment of urea hydrolysis wastewater.

[0058] Figure 4 The present invention provides a flow chart of the ammonia treatment method.

[0059] Description of reference numerals:

[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. Alkaline solution inlet; 212. First pH meter; 213. First connecting port; 214. Second dosing device; 22. Adjustment zone; 221. Second pH meter; 222. Acid solution inlet; 23. Partition plate; 24. Overflow space;

[0062] 3. Ultrafiltration device;

[0063] 4. Reverse osmosis device;

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

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

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

[0067] 8. Sludge dewatering machine;

[0068] 9. Urea hydrolysis wastewater pool;

[0069] 10. Fresh water tank. DETAILED DESCRIPTION

[0070] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0071] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0072] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0073] As attached Figure 1 As shown, the embodiment of the present invention discloses a urea hydrolysis wastewater resource treatment system, comprising 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 regulating zone 22, and the reaction zone 21 and the regulating zone 22 are connected;

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

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

[0077] The inlet of the ultrafiltration device 3 is connected to the neutral water sample outlet of the regulating area 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 treatment system, the urea-containing wastewater first enters the urea pretreatment device 1 from the urea hydrolysis wastewater tank 9 for precipitation pretreatment, and most of the impurities and sludge in the wastewater are separated from the solid-liquid separation of the wastewater. The treated primary decontaminated water sample enters the reaction zone 21 of the integrated reaction device 2, and the reaction zone 21 adjusts the pH value of the primary decontaminated water sample to be greater than or equal to 12. At this time, on the one hand, under the high alkaline environment, the ammonia nitrogen in the primary decontaminated water sample is almost all in the form of ammonia gas and escapes from the primary decontaminated water sample into the ammonia treatment device 6, and the ammonia treatment device 6 converts the ammonia gas into On the other hand, the high-alkaline water sample enters the regulating area 22 through the portion connected to the regulating area 22, and the regulating area 22 adjusts the pH value of the high-alkaline water sample to 6.5-7.5 to become a neutral water sample and then enters the ultrafiltration device 3 for ultrafiltration, and the obtained secondary decontaminated water sample enters the reverse osmosis device 4 for separation and concentration, and the generated fresh water is collected in the fresh water tank 10 for reuse in other devices in the factory, and the generated high-salt wastewater enters the bipolar membrane electrodialysis device 5, which can convert the salt in the high-salt wastewater into corresponding acid and alkali solution without introducing new components. Among them, 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, and there is no need to repeatedly add acid and alkali from the outside during the operation of the system, which effectively saves operating costs and labor costs. The in-factory reuse of multiple resources such as acid, alkali, nitrogen fertilizer and fresh water realizes the rational resource utilization of urea wastewater, and no other waste and secondary wastewater are generated during the treatment process of the urea hydrolysis wastewater resource treatment system, that is, while reasonably utilizing resources, no secondary pollution will be caused.

[0080] In order to enable the integrated reaction device 2 to complete a variety of operations in an integrated manner, such as Figure 2 As shown, the integrated reaction device 2 is provided with a partition 23, and the partition 23 separates the integrated reaction device 2 into a reaction zone 21 and a regulating zone 22 connected at the top. The space connected at the top of the reaction zone 21 and the regulating zone 22 is an overflow space 24, and the overflow space 24 is used to overflow the high-alkali water sample of the reaction zone 21 to the regulating zone 22, that is, when the internal water sample of the reaction zone 21 is adjusted to be greater than or equal to 12, the high-alkali water sample continues to rise and flows from the overflow space 24 into the regulating zone 22 to facilitate the subsequent further adjustment of the high-alkali water sample by the regulating zone 22. The design of the partition 23 enables the reactions of the reaction zone 21 and the regulating zone 22 to be carried out in an independent space, avoiding mutual interference, and reducing the space occupied by the integrated reaction device 2.

[0081] Furthermore, a sewage pipe 71 and an alkali solution inlet 211 are connected at the bottom of the reaction zone 21, and the alkali solution inlet 211 is connected to the alkali solution outlet of the alkali solution tank 51 in the bipolar membrane electrodialysis device 5; the reaction zone 21 is provided with a first pH meter 212, and the first connecting port 213 between the urea pretreatment device 1 and the reaction zone 21 is located between the first pH meter 212 and the alkali solution inlet 211 in the height direction. The recycled alkali solution generated by the bipolar membrane electrodialysis device 5 enters from the alkali solution inlet 211 at the bottom of the reaction zone 21, and can fully react with the primary decontaminated water sample entering from the first connecting port 213 between the urea pretreatment device 1 and the reaction zone 21 above. In order to monitor the pH value of the water sample after the primary decontaminated water sample is mixed with the alkali solution in real time, a first pH meter 212 is arranged above the first connecting port 213. The first pH meter 212 is electrically connected to the system. The pH value monitoring status of the first pH meter 212 is first obtained in the reaction zone 21, and then it is selected whether to add alkali solution from the alkali solution inlet 211 for adjustment as needed, that is, when the measured pH value is greater than or equal to 12, the reaction zone 21 operates normally, and when the measured pH value is less than 12, the input amount of alkali solution is increased through the alkali solution inlet 211 to achieve the operation standard of the reaction zone 21. In addition, the sludge generated by the reaction is discharged in time through the sewage pipe 71 connected at the bottom to prevent the sludge from clogging the alkali solution inlet 211 and the first connecting port 213.

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

[0083] When the pH value of the water sample in the reaction zone 21 reaches a standard of greater than or equal to 12, almost all of the ammonia nitrogen in the high-alkali wastewater in this environment exists and escapes in the form of ammonia gas, and enters the ammonia treatment device 6 through the area corresponding to the reaction zone 21 at the top of the integrated reaction device 2 and the gas pipeline 61 connected thereto, and a fan 62 is provided in the gas pipeline 61, which can more effectively transmit all the ammonia generated in the 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, which is convenient for guiding the ammonia gas to converge at the tip of the cone so that it can enter the ammonia treatment device 6 more smoothly through the inlet of the gas pipeline 61, thereby accelerating the transmission speed of the ammonia gas.

[0084] The area at the top of the integrated reaction device 2 corresponding to the regulating 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 regulating zone 22 is arranged at the top to mix with the high-alkali water sample overflowing from the upper overflow space 24 at the first time, so as to adjust the pH value of the water sample in the regulating zone 22 to 6.5-7.5 for subsequent ultrafiltration and reverse osmosis treatment. The regulating zone 22 is provided with a second pH meter 221, which is located at the connection between the regulating 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 absorption liquid holding chamber inside, which is connected to the water supply outlet of the industrial water pool 63 and the acid outlet of the bipolar membrane electrodialysis device 5 respectively, so that the industrial water supply and the acid are mixed to form an absorption liquid. The outlet of the gas pipeline 61 is located at the lower layer of the absorption liquid holding chamber, so that the ammonia entering from the reaction zone 21 can quickly contact with the absorption liquid to obtain any one or more combinations of ammonium chloride, ammonium bisulfate and ammonium sulfate, which can be used as nitrogen fertilizer for greening fertilization to achieve the rational resource utilization of ammonia nitrogen. A third pH meter 64 is provided in the absorption liquid holding chamber to measure the pH value of the absorption liquid in the ammonia treatment device 6; the optimal pH value of the absorption liquid is 4-5, and the absorption liquid with this acidity can continuously and effectively absorb ammonia and can avoid excessively intense reactions when the acidity is too low and produce unnecessary side reactions.

[0086] The urea pretreatment device 1 is connected to a first dosing device 11, and the first dosing device 11 has a flocculant outlet. The flocculant and coagulant aid enter the urea pretreatment device 1 through the first dosing device 11, so that impurities such as suspended matter and sludge in the urea-containing wastewater are precipitated, thereby achieving preliminary purification of the urea-containing wastewater. The urea pretreatment device 1 includes a sludge outlet for discharging impurities and sludge precipitation. The urea pretreatment device 1 also includes a primary decontaminated water sample outlet, and a primary decontaminated water sample pipeline 12 is connected between the primary decontaminated water sample outlet and the reaction zone 21 of the integrated reaction device 2. The periphery of the primary decontaminated water sample outlet is provided with a first turbidity meter 13, and the turbidity of the primary decontaminated water sample monitored by the first turbidity meter 13 must be less than 5NTU before it can enter the reaction zone 21 for subsequent treatment.

[0087] In order to rationally utilize the discharged sludge as a resource, the urea hydrolysis wastewater resource treatment system further includes a sludge concentration tank 7 and a sludge dewatering machine 8 which are connected in sequence;

[0088] The inlet of the sludge concentration 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, and the inlet of the sludge dewatering machine 8 is connected to the outlet of the sludge concentration tank 7.

[0089] Specifically, the sludge enters the sludge concentration tank 7 from the urea pretreatment device 1 and the reaction zone 21 through the sewage pipe 71 for concentration. The concentrated sludge is desludged by the sludge dewatering machine 8, and the generated water sample is recycled to the urea hydrolysis wastewater tank 9. The sludge and coal sample are mixed and burned in the furnace for energy supply in the plant, thereby realizing the resource utilization of sludge and effectively reducing the operating cost.

[0090] As attached Figure 3As shown, in addition to the above-mentioned urea hydrolysis wastewater resource treatment system, the present invention also provides a urea hydrolysis wastewater resource treatment method based on the operation of the above-mentioned urea hydrolysis wastewater resource treatment system. The urea hydrolysis wastewater resource treatment method corresponds to the above-mentioned urea hydrolysis wastewater resource treatment system embodiment. The urea hydrolysis wastewater resource treatment method described below and the urea hydrolysis wastewater resource treatment system described above can be referenced to each other.

[0091] A method for recycling urea hydrolysis wastewater comprises the following steps:

[0092] Step S1, urea wastewater enters the urea pretreatment device 1 from the urea hydrolysis wastewater tank 9 for sedimentation treatment, and generates primary decontaminated water sample and sludge after treatment. The primary decontaminated water sample enters the reaction zone 21, and the sludge enters the sludge concentration tank 7;

[0093] Step S2, controlling the amount of alkali solution input into the reaction zone 21 of the bipolar membrane electrodialysis device 5, and detecting the pH value of the water sample in the reaction zone 21 in real time,

[0094] If the pH value is ≥12, the current input amount of the wastewater sample and the input amount of the alkali solution are maintained;

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

[0096] The high-alkali water sample produced in the reaction zone 21 overflows to the adjustment zone 22, the ammonia produced enters the ammonia treatment device 6, and the impurities produced are precipitated and enter the sludge concentration tank 7;

[0097] Step S3, controlling the amount of acid solution inputted into the regulating zone 22 by the bipolar membrane electrodialysis device 5, and detecting the pH value of the water sample in the regulating zone 22 in real time,

[0098] If the pH value is 6.5-7.5, the current acid input and neutral water sample output are maintained.

[0099] If the pH value is less than 6.5, the amount of acid solution inputted into the regulating zone 22 of the bipolar membrane electrodialysis device 5 is reduced, or the amount of high-alkali water sample overflowing from the reaction zone 21 to the regulating zone 22 is increased, and the output of the neutral water sample is suspended until the pH value is 6.5-7.5;

[0100] If the pH value is greater than 7, the amount of acid solution inputted into the regulating zone 22 of the bipolar membrane electrodialysis device 5 is increased, or the amount of high-alkali water sample overflowing from the reaction zone 21 to the regulating zone 22 is reduced, and the output of the neutral water sample is suspended until the pH value is 6.5-7.5;

[0101] Step S4, the treated neutral water sample enters the ultrafiltration device 3, the ultrafiltration device 3 ultrafilters the neutral water sample, and the secondary decontaminated water sample enters the reverse osmosis device 4;

[0102] Step S5, the reverse osmosis device 4 performs reverse osmosis desalination on the secondary decontaminated water sample to obtain high-salt wastewater and fresh water, which are 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 solution and alkali solution, the acid solution is returned to the adjustment area 22 and the ammonia treatment device 6 for reuse, and the alkali solution is returned to the reaction area 21 for reuse.

[0104] During the operation, the acid, alkali, nitrogen fertilizer, fresh water and other resources are recycled within the factory, realizing the rational utilization of resources in the process of urea wastewater hydrolysis, which can greatly save costs. In addition, no other waste and secondary wastewater are generated during the treatment process using the above method, that is, while rationally utilizing resources, no secondary pollution will be caused.

[0105] When the alkali solution recycled from the bipolar membrane electrodialysis device 5 is insufficient to adjust the pH value of the water sample in the reaction zone 21 to 12, step S2 further includes: controlling the amount of alkali solution input into the reaction zone 21 by 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 ≥ 12 is not satisfied, and the amount of alkali solution input into the reaction zone 21 by the bipolar membrane electrodialysis device 5 is the maximum value, starting the second dosing device 214 until the pH value of the water sample in the reaction zone 21 is ≥ 12.

[0106] In addition, as attached Figure 4 As shown, step S2 also includes processing ammonia to achieve the conversion of ammonia nitrogen: controlling the amount of acid solution input from the bipolar membrane electrodialysis device 5 to the ammonia treatment device 6, and monitoring the pH value of the absorption liquid in the ammonia treatment device 6 in real time,

[0107] If the pH value = 4-5 is met, the current acid input and industrial pool 63 water sample output are maintained;

[0108] If the pH value is less than 4, the amount of acid solution inputted into the ammonia treatment device 6 by the bipolar membrane electrodialysis device 5 is reduced, or the amount of water sample extracted from the industrial water pool 63 is increased, and the entry of ammonia is suspended until the pH value is 4-5;

[0109] If the pH value is greater than 5, the amount of acid solution inputted into the ammonia treatment device 6 by the bipolar membrane electrodialysis device 5 is increased, or the amount of water sample extracted from the industrial water pool 63 is reduced, and the entry of ammonia is suspended until the pH value is 4-5.

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

[0111] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A urea hydrolysis wastewater resource treatment system, characterized in that: It comprises 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 comprises a reaction zone and a regulating zone, and the reaction zone and the regulating zone are in communication; The reaction zone is connected to the urea pretreatment device, and the reaction zone is connected to the alkali solution outlet of the bipolar membrane electrodialysis device, and the pH value of the water sample in the reaction zone is greater than or equal to 12; The regulating area is connected to the acid solution outlet of the bipolar membrane electrodialysis device, and the pH value of the water sample in the regulating area is 6.5-7.5; The inlet of the ultrafiltration device is connected to the neutral water sample outlet of the regulating zone; The inlet of the ammonia treatment device is communicated with the reaction zone.

2. The urea hydrolysis wastewater resource treatment system according to claim 1, characterized in that: The integrated reaction device is provided with a partition, which separates the integrated reaction device into the reaction zone and the adjustment zone connected at the top. The space connected at the top of the reaction zone and the adjustment zone is an overflow space, and the overflow space is used to overflow the water sample from the reaction zone to the adjustment zone.

3. The urea hydrolysis wastewater resource treatment system according to claim 1 or 2, characterized in that: The bottom of the reaction zone is connected with a sewage pipe and an alkali solution inlet, and the alkali solution inlet is connected with the alkali solution outlet of the bipolar membrane electrodialysis device; The reaction zone is provided with a first pH meter, and the communication port between the urea pretreatment device and the reaction zone is located between the first pH meter and the alkali solution inlet in the height direction; The reaction zone is also connected to a second dosing device for replenishing alkali solution.

4. The urea hydrolysis wastewater resource treatment system according to claim 1 or 2, characterized in that: The area at the top of the integrated reaction device corresponding to the reaction zone is connected to the ammonia treatment device through a gas pipeline; A fan is provided in the gas pipeline for transmitting the ammonia gas in 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.

5. The urea hydrolysis wastewater resource treatment system according to claim 1 or 2, characterized in that: The area at the top of the integrated reaction device corresponding to the regulating zone is connected to the acid outlet of the bipolar membrane electrodialysis device. The regulating zone is provided with a second pH meter, which is located at the connection between the regulating zone and the ultrafiltration device.

6. The urea hydrolysis wastewater resource treatment system according to claim 4, characterized in that: The ammonia treatment device has an absorption liquid containing chamber inside, and the absorption liquid containing chamber is respectively connected to the water supply outlet of the industrial water pool and the acid liquid outlet of the bipolar membrane electrodialysis device, so that the industrial water supply and the acid liquid are mixed to form the absorption liquid, and the outlet of the gas pipeline is located at the lower layer of the absorption liquid containing chamber; A third pH meter is provided in the absorption liquid containing chamber, and the third pH meter is used to measure the pH value of the absorption liquid in the ammonia treatment device; The pH value of the absorption liquid is 4-5.

7. The urea hydrolysis wastewater resource treatment system according to claim 1, characterized in that: The urea pretreatment device is connected to a first dosing device, and the first dosing device has a flocculant outlet; The urea pretreatment device comprises a sludge outlet and a primary decontaminated water sample outlet. A primary decontaminated water sample pipeline is connected between the primary decontaminated water sample outlet and the reaction zone of the integrated reaction device, and a first turbidity meter is arranged on the periphery of the primary decontaminated water sample outlet.

8. The urea hydrolysis wastewater resource treatment system according to 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 concentration tank is communicated with 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 communicated with the outlet of the sludge concentration tank.

9. A method for resource-based treatment of urea hydrolysis wastewater, applicable to the urea hydrolysis wastewater resource-based treatment system according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step S1, urea wastewater enters the urea pretreatment device from the urea hydrolysis wastewater tank for sedimentation treatment, and generates a primary decontaminated water sample and sludge after treatment, the primary decontaminated water sample enters the reaction zone, and the sludge enters the sludge concentration tank; Step S2, controlling the amount of alkali solution input into the reaction zone of the bipolar membrane electrodialysis device, and detecting the pH value of the water sample in the reaction zone in real time, If the pH value is ≥12, the current input amount of the wastewater sample and the input amount of the alkali solution are maintained; If the pH value is not ≥ 12, increasing the amount of alkali solution input into the reaction zone of the bipolar membrane electrodialysis device; The high-alkali water sample produced in the reaction zone overflows into the adjustment zone, the generated ammonia enters the ammonia treatment device, and the generated impurities precipitate into the sludge concentration tank; Step S3, controlling the amount of acid solution inputted into the regulating zone by the bipolar membrane electrodialysis device, and detecting the pH value of the water sample in the regulating zone in real time, If the pH value is 6.5-7.5, the current acid input and neutral water sample output are maintained; If the pH value is less than 6.5, the amount of acid solution inputted into the regulating zone by the bipolar membrane electrodialysis device is reduced, or the amount of high-alkali water sample overflowing from the reaction zone to the regulating zone is increased, and the output of neutral water sample is suspended until the pH value is 6.5-7.5; If the pH value is greater than 7, the amount of acid solution inputted into the regulating zone by the bipolar membrane electrodialysis device is increased, or the amount of high-alkali water sample overflowing from the reaction zone to the regulating zone is reduced, and the output of neutral water sample is suspended until the pH value is 6.5-7.5; Step S4, the treated neutral water sample enters the ultrafiltration device, the ultrafiltration device ultrafilters the neutral water sample, and the secondary decontaminated water sample enters the reverse osmosis device; Step S5, the reverse osmosis device performs reverse osmosis desalination on the secondary decontaminated water sample to obtain high-salt wastewater and fresh water, which are 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 the high-salt wastewater into acid solution and alkali solution, 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.

10. The method according to claim 9, characterized in that The step S2 further comprises: Controlling the amount of alkali solution input into the reaction zone by the bipolar membrane electrodialysis device, and detecting the pH value of the water sample in the reaction zone in real time, If the pH value is not ≥ 12, and the amount of alkali solution input from the bipolar membrane electrodialysis device to the reaction zone is at a maximum, the second dosing device is started until the pH value of the water sample in the reaction zone is ≥ 12; and / or The step S2 further comprises: Controlling the amount of acid solution input from the bipolar membrane electrodialysis device to the ammonia treatment device, and monitoring the pH value of the absorption liquid in the ammonia treatment device in real time, If the pH value = 4-5 is met, the current acid input and industrial pool water sample output are maintained; If the pH value is less than 4, the amount of acid solution input from the bipolar membrane electrodialysis device to the ammonia treatment device is reduced, or the amount of water sample extracted from the industrial water pool is increased, and the entry of ammonia is suspended until the pH value is 4-5; If the pH value is greater than 5, the amount of acid solution input from the bipolar membrane electrodialysis device to the ammonia treatment device is increased, or the amount of water sample extracted from the industrial water pool is reduced, and the entry of ammonia is suspended 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.

Images