Wastewater discharge system for coal chemical industry

Abstract

The utility model relates to a coal chemical industry wastewater discharge system which comprises a regulating tank, a secondary AO device, a separation unit and an adsorption unit, the regulating tank is used for homogenizing and mixing wastewater to be treated, a liquid inlet of the secondary AO device is communicated with the regulating tank, a liquid outlet of the secondary AO device is communicated with the separation unit, the separation unit is communicated with the adsorption unit, the separation unit is used for separating produced water in the wastewater, and the adsorption unit is used for adsorbing the wastewater. The adsorption unit is used for adsorbing residual organic matters and nitrate in the wastewater. In the coal chemical industry wastewater discharge system provided by the invention, the secondary AO device can effectively remove most of organic matters and total nitrogen in the wastewater, and in order to further optimize the treatment effect, the separation unit is arranged behind the secondary AO device, so that the design can effectively prevent suspension and most of produced water from entering the adsorption unit, and the treatment effect is improved. In addition, residual organic matters and nitrate in the wastewater are removed through the adsorption unit, so that the treatment effect can be remarkably improved, and the overall treatment cost can be greatly reduced.

Description

Technical Field

[0001] This disclosure relates to the field of wastewater treatment technology, and more specifically, to a coal chemical wastewater discharge system. Background Technology

[0002] Coal chemical wastewater contains large amounts of organic matter and total nitrogen. Currently, biological denitrification is commonly used to treat this type of wastewater in order to achieve the goal of zero discharge. However, during the zero discharge process, although biological denitrification can remove most of the organic matter and total nitrogen, these pollutants will be further concentrated with the operation of subsequent concentration units and will eventually be separated in the form of mixed salts, resulting in high disposal costs.

[0003] For organic matter in concentrated brine, advanced oxidation processes are currently the primary treatment method. However, conventional advanced oxidation technologies generally suffer from high energy consumption or high operating costs. Regarding total nitrogen, although biochemical processes can remove the vast majority of ammonia nitrogen, a certain amount of nitrate remains in the effluent. Currently, effective methods for removing nitrate from concentrated brine are not yet mature. Many technologies in the pilot-scale stage mainly rely on electrochemical methods for nitrate removal; however, this method suffers from drawbacks such as high energy consumption and easy corrosion of the electrodes, limiting its widespread application. Utility Model Content

[0004] In view of this, the present disclosure provides a coal chemical wastewater discharge system to address the technical deficiencies in the prior art.

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

[0006] This disclosure provides a coal chemical wastewater discharge system, comprising:

[0007] An equalization tank, which is configured to homogenize and mix the wastewater to be treated;

[0008] A secondary AO device has an inlet and an outlet. The inlet is configured to communicate with the equalization tank. Homogenized wastewater flows into the secondary AO device through the inlet. The secondary AO device is configured to remove organic matter and total nitrogen from the wastewater.

[0009] A separation unit is configured to communicate with the outlet of the secondary AO device and is configured to separate the product water from the wastewater.

[0010] An adsorption unit is configured to communicate with the separation unit for adsorbing residual organic matter and nitrate ions in wastewater.

[0011] In one embodiment of this disclosure, the secondary AO device includes a primary A tank, a primary O tank, a secondary A tank, and a secondary O tank connected in sequence. The primary A tank is configured to perform a denitrification reaction, the primary O tank is configured to perform a nitrification reaction, the secondary A tank is configured to degrade residual total nitrogen in wastewater, and the secondary O tank is configured to decompose excess carbon sources. Submersible agitators are installed in the primary A tank and the secondary A tank, and aeration devices are installed in the primary O tank and the secondary O tank to provide oxygen.

[0012] In one embodiment of this disclosure, the primary A pool, the primary O pool, the secondary A pool, and the secondary O pool are configured to be separated by a partition, and an overflow port is provided on the partition for connecting the primary A pool, the primary O pool, the secondary A pool, and the secondary O pool.

[0013] In one embodiment of this disclosure, the secondary AO device is provided with a cover plate for isolating air.

[0014] In one embodiment of this disclosure, a first loop is provided between the primary A tank and the primary O tank, the first loop being configured to return wastewater from the primary O tank to the primary A tank, and a second loop is provided between the secondary A tank and the secondary O tank, the second loop being configured to return wastewater from the secondary O tank to the secondary A tank.

[0015] In one embodiment of this disclosure, the separation unit includes a membrane bioreactor configured to communicate with the outlet of the secondary AO device, the membrane bioreactor being configured to retain suspension and organic matter.

[0016] In one embodiment of this disclosure, the separation unit further includes a membrane concentration device having a first inlet, a first outlet, and a second outlet. The first inlet is configured to communicate with the membrane bioreactor, the first outlet is used to discharge permeate, and the second outlet is configured to communicate with the adsorption unit.

[0017] In one embodiment of this disclosure, the adsorption unit includes an organic matter adsorption device and a nitrate adsorption device, the organic matter adsorption device having a second inlet and an outlet, the second inlet being configured to communicate with a second outlet of the membrane concentration device, and the outlet being configured to communicate with the nitrate adsorption device.

[0018] In one embodiment of this disclosure, the coal chemical wastewater discharge system further includes an evaporation crystallization device configured to be connected to the nitrate adsorption device for collecting sodium chloride and sodium sulfate crystals in the wastewater.

[0019] In one embodiment of this disclosure, the chemical wastewater discharge system further includes a mother liquor drying device configured to be connected to the evaporation and crystallization device for evaporating the remaining wastewater.

[0020] In the coal chemical wastewater discharge system disclosed herein, the secondary AO device can effectively remove most of the organic matter and total nitrogen in the wastewater. In order to further optimize the treatment effect, a separation unit is set after the secondary AO device. This design can effectively prevent the suspension and most of the product water from entering the adsorption unit and affecting the adsorption efficiency of the adsorption unit. In addition, removing the remaining organic matter and nitrate in the wastewater through the adsorption unit can not only significantly improve the treatment effect, but also greatly reduce the overall treatment cost.

[0021] Other features and advantages of this disclosure will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a coal chemical wastewater discharge system provided in one embodiment of the present disclosure.

[0023] 1-Equalization tank; 11-Agitator;

[0024] 2-Secondary AO device; 21-Primary A tank; 22-Primary O tank; 23-Secondary A tank; 24-Secondary O tank; 211-Inlet; 212-Outlet; 213-Submersible agitator; 214-Aeration device; 215-Cover plate; 216-First loop; 217-Second loop;

[0025] 3- Membrane bioreactor;

[0026] 4-Membrane concentration unit; 41-First inlet; 42-First outlet; 43-Second outlet;

[0027] 5-Organic adsorption device; 51-Second inlet; 52-Outlet;

[0028] 6-Nitrate adsorption device; 7-Evaporation crystallization device; 8-Mother liquor drying device. Detailed Implementation

[0029] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present disclosure.

[0030] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use.

[0031] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0032] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0033] The specific embodiments of this disclosure are described below with reference to the accompanying drawings.

[0034] In this article, terms such as "up," "down," "front," "back," "left," and "right" are used only to indicate the relative positional relationship between related parts, rather than to define the absolute position of these related parts.

[0035] In this article, "first," "second," etc., are used only to distinguish one another, and not to indicate degree of importance, order, or prerequisite for each other.

[0036] In this document, terms such as “equal” and “same” are not strict mathematical and / or geometric limitations, but also include errors that are understandable to those skilled in the art and permissible in manufacturing or use.

[0037] First, the terms and concepts involved in one or more embodiments will be explained.

[0038] Secondary AO unit: A secondary AO unit refers to a two-stage anaerobic-aerobic process unit used in wastewater treatment.

[0039] Primary A Tank / Secondary A Tank: Primary A Tank represents the primary anaerobic tank, and Secondary A Tank represents the secondary anaerobic tank.

[0040] Primary O-tank / Secondary O-tank: Primary O-tank represents the primary aerobic tank, and secondary O-tank represents the secondary aerobic tank.

[0041] This disclosure relates to a coal chemical wastewater discharge system, including an equalization tank, a secondary AO device, a separation unit, and an adsorption unit. The equalization tank is used to homogenize and mix the wastewater to be treated. The inlet of the secondary AO device is connected to the equalization tank, and the outlet is connected to the separation unit. The separation unit is connected to the adsorption unit. The separation unit is used to separate the product water from the wastewater, and the adsorption unit is used to adsorb the remaining organic matter and nitrates in the wastewater.

[0042] In the coal chemical wastewater discharge system disclosed in this disclosure, the secondary AO (anaerobic-aerobic) unit can efficiently remove most of the organic matter and total nitrogen from the wastewater. To further optimize the treatment effect, a separation unit is set after the secondary AO unit. This design effectively prevents the suspension and most of the water from entering the adsorption unit, avoiding the problem of decreased adsorption effect caused by this. Using the adsorption unit to remove the remaining organic matter and nitrate in the wastewater not only significantly improves the treatment effect but also greatly reduces the overall treatment cost. Compared with traditional methods with high energy consumption or high cost, such as electrochemical methods or advanced oxidation processes, the adsorption method has significant advantages such as simple operation, low energy consumption, and low maintenance cost.

[0043] For ease of understanding, please refer to the following: Figure 1 The specific structure and working principle of the coal chemical wastewater discharge system disclosed herein will be described in detail with reference to one embodiment.

[0044] like Figure 1 As shown, this disclosure provides a coal chemical wastewater discharge system, including: an equalization tank 1, a secondary AO device 2, a separation unit, and an adsorption unit. The equalization tank 1 is used to homogenize and mix the wastewater to be treated. The secondary AO device 2 has an inlet 211 and an outlet 212. The inlet 211 is connected to the equalization tank 1, and the homogenized wastewater flows into the secondary AO device 2 through the inlet 211. The secondary AO device 2 is used to remove organic matter and total nitrogen from the wastewater. The separation unit is connected to the outlet 212 of the secondary AO device 2 and is used to separate the product water from the wastewater. The adsorption unit is connected to the separation unit and is used to adsorb residual organic matter and nitrate ions from the wastewater.

[0045] Specifically, to ensure the stability of the wastewater entering the secondary AO unit 2, this disclosure includes an equalization tank 1 before the secondary AO unit 2 for homogenizing, mixing, and buffering the wastewater. An agitator 11 is installed in the equalization tank 1 to ensure sufficient homogenization and mixing of the wastewater, thereby guaranteeing the stability and efficiency of the subsequent treatment process. The homogenized wastewater flows into the secondary AO unit 2 through the inlet 211. The secondary AO unit 2 is equipped with four reaction tanks connected in sequence, which are designated as primary A tank 21, primary O tank 22, secondary A tank 23, and secondary O tank 24. Denitrifying bacteria are introduced into the primary A tank 21. The primary A tank 21 uses the denitrification reaction of the denitrifying bacteria under anoxic conditions to convert nitrate or nitrite in the original wastewater into nitrogen gas. Denitrifying bacteria are very common in nature, and most of them are facultative. In an environment with extremely low dissolved oxygen concentration, they can use oxygen in nitrates as electron acceptors, while organic matter serves as a carbon source and electron donor to provide energy and is oxidized and stabilized. After the denitrifying bacteria convert the nitrate or nitrite in the original wastewater into nitrogen gas, it is discharged from the system. At the same time, the organic matter in the wastewater is consumed as a carbon source.

[0046] Furthermore, the wastewater treated in the primary A tank 21 flows into the primary O tank 22. Nitrifying bacteria are introduced into the primary O tank 22 to convert nitrogen and ammonia in the wastewater into nitrate through nitrification. Specifically, the nitrification reaction includes two steps. The first step is called the nitrosation process, in which nitrite-oxidizing bacteria (including Nitrostomyces, Helicobacter, and Nitrococcus) convert ammonia nitrogen in the wastewater into nitrite. The second step is called the nitrification process, in which nitrate-oxidizing bacteria (including Nitrobacter, Helicobacter, and Coccus) further oxidize nitrite into nitrate. Nitrostomy bacteria and nitrate-oxidizing bacteria are collectively referred to as nitrifying bacteria.

[0047] A first loop 216 is set between the first-stage A tank 21 and the first-stage O tank 22. A pump is installed in the first loop 216. The pump in the first loop 216 can pump the wastewater in the first-stage O tank 22 back to the first-stage A tank 21. At this time, the wastewater treated by the first-stage O tank 22 contains a large amount of nitrate. After flowing back to the first-stage O tank 22, it can continue to carry out the denitrification reaction, converting the nitrate into nitrogen gas and then discharging it from the system, while simultaneously consuming the organic matter in the wastewater. Meanwhile, some wastewater from the primary O tank 22 will also flow into the secondary A tank 23 for denitrification. Due to the reaction in the primary A tank 21 and the primary O tank 22, a large amount of organic matter in the wastewater is consumed, and there is a lack of sufficient organic matter in the wastewater as a carbon source for the denitrification reaction. Therefore, the secondary A tank 23 needs to add an external carbon source to ensure the effective progress of the denitrification reaction in the secondary A tank 23. The wastewater after treatment in the secondary A tank 23 contains the excess carbon source after replenishment. At this time, the nitrifying bacteria in the secondary O tank 24 continue to convert ammonia nitrogen in the wastewater into nitrate under aerobic conditions and decompose the excess carbon source. A second loop 217 is set between the secondary A tank 23 and the secondary O tank 24. A pump is also set in the second loop 217 to transport the nitrate produced by the reaction in the secondary O tank 24 back to the secondary A tank 23 for reaction. Most of the organic matter and ammonia nitrogen in the wastewater after passing through the secondary AO unit 2 are consumed and decomposed, but a small amount of unreacted organic matter and nitrates will still exist. In order to improve the treatment effect and reduce the treatment cost, this disclosure sets up a separation unit and an adsorption unit in sequence after the secondary AO unit 2 for subsequent impurity removal operations.

[0048] Furthermore, after the wastewater flows out through the secondary AO device 2, it enters the separation unit, which is equipped with a reverse osmosis membrane. During the reverse osmosis process, water molecules are forced through the membrane by applying pressure higher than the natural osmotic pressure, while most dissolved salts, organic matter, and other impurities are retained. After treatment, the first outlet 42 discharges product water that meets higher water quality standards. This product water can meet stricter discharge standards or be directly recycled. The concentrated water enters the adsorption unit, which specifically includes organic matter adsorption and nitrate adsorption, used to remove the remaining trace amounts of organic matter and nitrate ions in the wastewater.

[0049] like Figure 1 As shown, the secondary AO device 2 includes a primary A tank 21, a primary O tank 22, a secondary A tank 23, and a secondary O tank 24 connected in sequence. The primary A tank 21 is used for denitrification, the primary O tank 22 is used for nitrification, the secondary A tank 23 is used to degrade residual total nitrogen in the wastewater, and the secondary O tank 24 is used to decompose excess carbon sources. Submersible agitators 213 are installed in the primary A tank 21 and the secondary A tank 23, and aeration devices 214 are installed in the primary O tank 22 and the secondary O tank 24 to provide oxygen.

[0050] Specifically, in the first-stage A tank 21, under anoxic conditions, denitrifying bacteria reduce nitrates or nitrites in the original wastewater and return liquid to nitrogen gas, while some organic matter is also degraded.

[0051] The main equation for the denitrification reaction is as follows:

[0052] C5H7O2N+4NO3 - →5CO2 + NH3 + 2N2↑ + 4OH -

[0053] In this process, denitrifying bacteria use organic matter as a carbon source and electron donor, and oxygen from nitrates as an electron acceptor to complete the denitrification reaction. Submersible mixers 213 are installed in the primary A tank 21 and the secondary A tank 23 to thoroughly mix the wastewater with the return liquid from the first loop 216, ensuring a uniform distribution of nitrates and organic matter. The wastewater treated in the primary A tank 21 flows into the primary O tank 22. Aeration devices 214 are installed in the primary O tank 22 and the secondary O tank 24 to provide oxygen. Under aerobic conditions, nitrifying bacteria convert ammonia nitrogen into nitrates, further decomposing the organic matter in the wastewater.

[0054] The nitration reaction consists of two steps:

[0055] Nitrification process: Nitrosinophils oxidize ammonia nitrogen into nitrite.

[0056] 2NH4 + +3O2→2NO2 - +4H + +2H2O

[0057] Nitrification process: Nitrification bacteria further oxidize nitrite into nitrate.

[0058] 2NO2 - +O2→2NO3 -

[0059] The wastewater treated by the primary O tank 22 is pumped back to the primary A tank 21 by the first loop 216 to continue the denitrification reaction. At the same time, some of the wastewater in the primary O tank 22 will also flow into the secondary A tank 23 for denitrification. Since the wastewater has undergone the reaction in the primary A tank 21 and the primary O tank 22, a large amount of organic matter in the wastewater has been consumed. There is not enough organic matter in the wastewater as a carbon source for the denitrification reaction. Therefore, an external carbon source needs to be added to the secondary A tank 23 to ensure the effective progress of the denitrification reaction in the secondary A tank 23.

[0060] The denitrification reaction in secondary tank A 23 is similar to that in primary tank A 21. However, in secondary tank A 23, because the wastewater has already undergone nitrification in primary tank O 22, the nitrate concentration is higher, making the denitrification reaction more significant. Furthermore, since the wastewater has already been treated by primary tanks A 21 and O 22, a large amount of organic matter in the wastewater has been consumed, resulting in a lack of sufficient organic matter as a carbon source for the denitrification reaction. Therefore, secondary tank A 23 requires an external carbon source (methanol wastewater or other carbon sources) to ensure the effective conduct of the denitrification reaction. The wastewater after treatment in secondary tank A 23 contains excess carbon source after replenishment. At this time, nitrifying bacteria in secondary tank O 24 continue to convert ammonia nitrogen in the wastewater into nitrate under aerobic conditions and decompose the excess carbon source. A second loop 217 is set between secondary tank A 23 and secondary tank O 24 to transport the nitrate produced in secondary tank O 24 back to secondary tank A 23 for further reaction.

[0061] like Figure 1 As shown, the primary A pool 21, the primary O pool 22, the secondary A pool 23, and the secondary O pool 24 are separated by partitions, and overflow ports are provided on the partitions to connect the primary A pool 21, the primary O pool 22, the secondary A pool 23, and the secondary O pool 24.

[0062] Specifically, the primary A tank 21, primary O tank 22, secondary A tank 23, and secondary O tank 24 are separated by partitions to ensure that each tank functions independently and does not interfere with each other. Overflow outlets are provided on the partitions to connect the tanks, allowing wastewater to flow naturally from one tank to the next. This design ensures continuous flow of wastewater and ensures that each tank can fully complete its specific treatment task.

[0063] like Figure 1 As shown, the secondary AO device 2 is equipped with a cover plate 215 to isolate air.

[0064] Specifically, the secondary AO unit 2 is equipped with a cover plate 215 to isolate air and prevent external oxygen from entering the unit, providing an oxygen-deficient environment for the primary A tank 21 and the secondary A tank 23. Since nitrification occurs in the primary O tank 22 and the secondary O tank 24, an aeration device 214 is added to the primary O tank 22 and the secondary O tank 24 to provide oxygen. Furthermore, an exhaust port is provided on the cover plate 215 above the primary A tank 21 and the secondary A tank 23 to discharge the nitrogen generated during the denitrification process, preventing gas accumulation from affecting the equipment and operation.

[0065] according to Figure 1 As shown, a first loop 216 is provided between the primary A pool 21 and the primary O pool 22. The first loop 216 is used to return the wastewater in the primary O pool 22 to the primary A pool 21. A second loop 217 is provided between the secondary A pool 23 and the secondary O pool 24. The second loop 217 is used to return the wastewater in the secondary O pool 24 to the secondary A pool 23.

[0066] Specifically, a first loop 216 is provided between primary A tank 21 and primary O tank 22 to recirculate wastewater from primary O tank 22 back to primary A tank 21. This design helps to transfer the nitrates generated in primary O tank 22 back to primary A tank 21 for continued denitrification, thereby reducing the treatment pressure on secondary A tank 23 and improving reaction efficiency. A second loop 217 is provided between secondary A tank 23 and secondary O tank 24 to recirculate wastewater from secondary O tank 24 back to secondary A tank 23. This design also helps to transfer the nitrates generated in secondary O tank 24 back to secondary A tank 23 for continued denitrification, further reducing nitrates in the wastewater. The design of the first loop 216 and the second loop 217 allows wastewater to circulate between different stages, ensuring the full progress of denitrification. By recirculating the nitrates from primary O tank 22 and secondary O tank 24 back to primary A tank 21 and secondary A tank 23, nitrates can be further removed, improving overall treatment efficiency.

[0067] like Figure 1 As shown, the separation unit includes a membrane bioreactor 3, which is connected to the outlet 212 of the secondary AO device 2. The membrane bioreactor 3 is used to retain suspension and organic matter.

[0068] Specifically, the membrane bioreactor (MBR) is a wastewater treatment process that combines the traditional activated sludge process with membrane separation technology. It uses membrane modules to replace the traditional secondary sedimentation tank to achieve solid-liquid separation, thereby efficiently removing suspended solids, organic matter and other pollutants from wastewater. Wastewater treated by the secondary AO unit 2 is sent to the membrane module. Under the action of pressure difference, water molecules and other small molecule solutes permeate through the membrane, while large molecules such as microorganisms and suspended particles are retained.

[0069] like Figure 1 As shown, the separation unit also includes a membrane concentration device 4, which has a first inlet 41, a first outlet 42, and a second outlet 43. The first inlet 41 is connected to the membrane bioreactor 3, the first outlet 42 is used to discharge the produced water, and the second outlet 43 is connected to the adsorption unit.

[0070] Specifically, the first inlet 41 of the membrane concentration unit 4 is connected to the membrane bioreactor 3 to treat the wastewater passing through the membrane bioreactor 3. A reverse osmosis membrane is installed inside the membrane concentration unit 4. The membrane concentration unit 4 mainly uses reverse osmosis membrane technology to achieve deep purification and concentration of water. During the reverse osmosis process, water molecules are forced to permeate through the membrane by applying pressure higher than the natural osmotic pressure, while most dissolved salts, organic matter, and other impurities are retained. The separated permeate flows out from the first outlet 42, which can meet stricter discharge standards or be directly recycled. The remaining concentrated water flows into the adsorption unit from the second outlet 43 for further removal of residual organic matter and harmful substances such as nitrates. In this way, the entire system not only ensures efficient water resource recycling but also achieves an environmentally friendly wastewater treatment process. Figure 1 As shown, the adsorption unit includes an organic matter adsorption device 5 and a nitrate adsorption device 6. The organic matter adsorption device 5 has a second inlet 51 and an outlet 52. The second inlet 51 is connected to the second outlet 43 of the membrane concentration device 4, and the outlet 52 is used to connect to the nitrate adsorption device 6.

[0071] Specifically, the adsorption unit includes an organic matter adsorption device 5 and a nitrate adsorption device 6. The second inlet 51 of the organic matter adsorption device 5 is connected to the second outlet 43 of the membrane concentration device 4, allowing the concentrated water produced by the membrane concentration device 4 to flow to the organic matter adsorption device 5 for further treatment. This process ensures that organic pollutants in the water are removed to the maximum extent, providing a cleaner foundation for subsequent treatment. Similarly, the water after preliminary purification enters the nitrate adsorption device 6 for further removal of nitrate. In the organic matter adsorption device 5, a macroporous adsorption resin specifically designed for organic wastewater treatment is used. Due to its unique pore size and network structure, this resin exhibits excellent removal performance for organic matter in wastewater, with advantages such as high adsorption capacity, high efficiency removal rate, and excellent elution rate. In the nitrate adsorption device 6, a macroporous styrene-based strong base anion exchange resin is used. Due to its specific manufacturing process and active groups, this resin exhibits extremely high selective removal capacity for nitrate and nitrite in water when sulfate and chloride ions coexist.

[0072] It is worth noting that both the macroporous adsorption resin used for adsorbing organic matter and the anion exchange resin used for adsorbing nitrate ions possess excellent elution performance. Eluting these used resins in sodium chloride or sodium sulfate solutions, respectively, effectively regenerates the resins, thereby reducing operating costs and improving system sustainability. In particular, the regenerated liquid from the macroporous adsorption resin can be reintroduced into the secondary A tank 23 as a carbon source supplement, which not only reduces the demand for external carbon sources but also further lowers the system's operating costs. This resource recovery and recycling method reflects the development direction of modern wastewater treatment technology: pursuing efficient, economical, and environmentally friendly solutions.

[0073] like Figure 1 As shown, the coal chemical wastewater discharge system also includes an evaporation crystallization device 7, which is connected to a nitrate adsorption device 6 and is used to collect sodium chloride and sodium sulfate crystals in the wastewater.

[0074] Specifically, the wastewater treated by the organic matter adsorption device 5 and the nitrate adsorption device still contains other high concentrations of salts. To address this issue, the system design directly connects the evaporation crystallization device 7 to the nitrate adsorption device 6 to receive wastewater that still contains high concentrations of dissolved salts after the previous treatment. At this stage, most of the organic matter and nitrates in the wastewater have been removed, but to further improve resource utilization, it is necessary to separate the sodium chloride and sodium sulfate in the wastewater in crystalline form.

[0075] Furthermore, the wastewater entering the evaporation crystallization unit 7 is first preheated to a suitable temperature to improve the efficiency of the subsequent evaporation process. Inside the evaporation crystallization unit 7, the wastewater is heated, causing the water to gradually evaporate, while the sodium chloride and sodium sulfate dissolved in the water gradually concentrate. As the evaporation process continues, the solution reaches a supersaturated state and sodium chloride and sodium sulfate crystals begin to precipitate. By precisely controlling factors such as temperature and stirring speed, crystal growth can be promoted, forming larger sodium chloride and sodium sulfate crystals. Subsequently, a centrifuge or other solid-liquid separation equipment is used to separate the formed crystals from the mother liquor, thereby obtaining pure sodium chloride and sodium sulfate crystals. The evaporation crystallization unit 7 not only reduces pollutant emissions but also achieves effective resource recovery. For example, the sodium chloride or sodium sulfate crystals obtained from the evaporation crystallization process can be dissolved and used as a desorbent to react with saturated resin, realizing the resin regeneration process. This method not only reduces operating costs but also promotes resource recycling, embodying a win-win strategy of environmental protection and economic benefits. Through this comprehensive treatment solution, the entire wastewater treatment system not only meets strict discharge standards, but also maximizes resource utilization, which aligns with the concept of sustainable development.

[0076] like Figure 1As shown, the chemical wastewater discharge system also includes a mother liquor drying device 8, which is connected to an evaporation crystallization device 7 for evaporating the remaining wastewater.

[0077] Specifically, in chemical wastewater discharge systems, to further treat the mother liquor remaining after treatment by the evaporation crystallization device 7, a mother liquor drying device 8 is usually introduced. This mother liquor contains a high concentration of dissolved solids and other substances that are difficult to separate through conventional evaporation crystallization. The mother liquor drying device 8 mainly adopts heat treatment to completely evaporate the water in the mother liquor by heating, thereby leaving dry solid residues. The solid residues after drying can be safely disposed of or further processed and utilized. For example, some residues may contain valuable minerals or other recyclable components, which can be extracted and reused through appropriate processes, while worthless or harmful residues must be properly disposed of in accordance with relevant regulations to prevent secondary pollution.

[0078] In the coal chemical wastewater discharge system disclosed herein, the secondary AO unit 2 can effectively remove most of the organic matter and total nitrogen in the wastewater. To further optimize the treatment effect, a separation unit is set after the secondary AO unit 2. This design can effectively prevent microorganisms and most of the water in the secondary AO unit 2 from entering the adsorption unit, avoiding a reduction in the adsorption efficiency of the adsorption unit due to the presence of microorganisms and excess water. In addition, removing the remaining organic matter and nitrate in the concentrated water through the adsorption unit can not only significantly improve the treatment effect, but also greatly reduce the overall treatment cost.

[0079] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that this disclosure is not limited to the described order of actions, because according to this disclosure, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to this disclosure.

[0080] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0081] The preferred embodiments disclosed above are merely illustrative of this disclosure. The optional embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this disclosure. These embodiments are selected and specifically described in this disclosure to better explain the principles and practical applications of this disclosure, thereby enabling those skilled in the art to better understand and utilize this disclosure. This disclosure is limited only by the claims and their full scope and equivalents.

Claims

1. A coal chemical wastewater discharge system, characterized in that, include: Equalization tank (1), which is configured to homogenize and mix the wastewater to be treated; A secondary AO device (2) has an inlet (211) and an outlet (212). The inlet (211) is configured to communicate with the equalization tank (1). The homogenized wastewater to be treated flows into the secondary AO device (2) through the inlet (211). The secondary AO device (2) is configured to remove organic matter and total nitrogen from the wastewater. A separation unit is configured to communicate with the outlet (212) of the secondary AO device (2) and is configured to separate the product water from the wastewater. An adsorption unit is configured to communicate with the separation unit for adsorbing residual organic matter and nitrate ions in wastewater.

2. The coal chemical wastewater discharge system according to claim 1, characterized in that, The secondary AO device (2) includes a primary A tank (21), a primary O tank (22), a secondary A tank (23), and a secondary O tank (24) connected in sequence. The primary A tank (21) is configured to carry out denitrification, the primary O tank (22) is configured to carry out nitrification, the secondary A tank (23) is configured to degrade residual total nitrogen in wastewater, and the secondary O tank (24) is configured to decompose excess carbon sources. Submersible agitators (213) are installed in the primary A tank (21) and the secondary A tank (23), and aeration devices (214) are installed in the primary O tank (22) and the secondary O tank (24) to provide oxygen.

3. The coal chemical wastewater discharge system according to claim 2, characterized in that, The primary A pool (21), primary O pool (22), secondary A pool (23) and secondary O pool (24) are configured to be separated by a partition, and an overflow port is provided on the partition for connecting the primary A pool (21), primary O pool (22), secondary A pool (23) and secondary O pool (24).

4. The coal chemical wastewater discharge system according to claim 3, characterized in that, The secondary AO device (2) is provided with a cover plate (215) to isolate air.

5. The coal chemical wastewater discharge system according to claim 4, characterized in that, A first loop (216) is provided between the primary A pool (21) and the primary O pool (22). The first loop (216) is configured to return the wastewater in the primary O pool (22) to the primary A pool (21). A second loop (217) is provided between the secondary A pool (23) and the secondary O pool (24). The second loop (217) is configured to return the wastewater in the secondary O pool (24) to the secondary A pool (23).

6. The coal chemical wastewater discharge system according to claim 1, characterized in that, The separation unit includes a membrane bioreactor (3) configured to communicate with the outlet (212) of the secondary AO device (2) and configured to retain suspension and organic matter.

7. The coal chemical wastewater discharge system according to claim 6, characterized in that, The separation unit further includes a membrane concentration device (4), which has a first inlet (41), a first outlet (42), and a second outlet (43). The first inlet (41) is configured to communicate with the membrane bioreactor (3), the first outlet (42) is used to discharge product water, and the second outlet (43) is configured to communicate with the adsorption unit.

8. The coal chemical wastewater discharge system according to claim 7, characterized in that, The adsorption unit includes an organic matter adsorption device (5) and a nitrate adsorption device (6). The organic matter adsorption device (5) has a second inlet (51) and an outlet (52). The second inlet (51) is configured to communicate with the second outlet (43) of the membrane concentration device (4), and the outlet (52) is configured to communicate with the nitrate adsorption device (6).

9. The coal chemical wastewater discharge system according to claim 8, characterized in that, The coal chemical wastewater discharge system also includes an evaporation crystallization device (7), which is configured to be connected to the nitrate adsorption device (6) for collecting sodium chloride and sodium sulfate crystals in the wastewater.

10. The coal chemical wastewater discharge system according to claim 9, characterized in that, The chemical wastewater discharge system also includes a mother liquor drying device (8), which is configured to be connected to the evaporation crystallization device (7) for evaporating the remaining wastewater.

Images