A desulfurization wastewater clarification system

Abstract

The present application relates to the field of power plant desulfurization wastewater treatment, and particularly relates to a desulfurization wastewater clarification system. The system comprises a pretreatment unit and a clarification unit. The pretreatment unit comprises an absorption tower, a gypsum cyclone, a dehydration set and a gypsum overflow tank. The absorption tower is in communication with the gypsum cyclone. The gypsum cyclone is in communication with the gypsum overflow tank and the dehydration set. The dehydration set is in communication with the clarification unit. The clarification unit comprises a multistage sedimentation clarification tank. The multistage sedimentation clarification tank is in communication with the absorption tower, the dehydration set and / or the gypsum overflow tank. The desulfurization wastewater clarification system provided by the present application integrates the pretreatment unit and the clarification unit, and utilizes the synergistic effect of the absorption tower, the gypsum cyclone, the dehydration set and the gypsum overflow tank to achieve effective pre-separation and multistage sedimentation clarification of the desulfurization wastewater.

Description

Technical Field

[0001] This invention relates to the field of desulfurization wastewater treatment in power plants, and more particularly to a desulfurization wastewater clarification system. Background Technology

[0002] In coal-fired power plants, wet desulfurization processes are widely used to remove sulfur dioxide (SO2) from flue gas. However, this process generates desulfurization wastewater containing complex components, including heavy metals, chloride ions, sulfates, and other suspended solids. Direct discharge of this untreated or incompletely treated wastewater will cause serious environmental pollution.

[0003] Currently, the most common method in desulfurization wastewater treatment is clarification after adding chemical agents. This method is mainly implemented through a "three-tank" system, where raw wastewater sequentially passes through a neutralization tank, a settling tank, and a flocculation tank. At each stage, calcium hydroxide, organic sulfur, a flocculant (such as polyferric chloride), and a coagulant aid (such as PAM) are added respectively. Through repeated stirring and mixing, the raw wastewater enters the clarification tank for neutralization, flocculation, and sedimentation. The supernatant is discharged as treated wastewater, while the bottom sediment is treated as sludge and dewatered. In this process, the raw wastewater first enters the neutralization tank, then the settling tank and the flocculation tank, and finally the clarification tank. The supernatant in the clarification tank can be further treated or directly discharged, while the bottom sediment needs to undergo sludge dewatering treatment using equipment such as a plate and frame filter press, and is ultimately transported for disposal.

[0004] Although the above methods can remove pollutants from desulfurization wastewater to some extent, they have the following significant problems:

[0005] Secondary pollution risk: Due to the need to add a large amount of chemical agents, the residual dosage of the chemical agents in the treated water may be too high, which will increase the difficulty of subsequent treatment and may cause secondary pollution problems such as pH imbalance and salt accumulation.

[0006] High costs: The cost of chemicals is high, and when combined with electricity consumption, equipment maintenance and sludge disposal costs, the overall operating cost is high.

[0007] Process complexity: The entire process involves multiple stages, each requiring precise parameter control, which makes operation difficult and places high demands on equipment, increasing the failure rate and maintenance costs.

[0008] Resource waste: Traditional treatment methods fail to effectively recover and utilize useful components in sludge, such as gypsum, leading to resource waste. Furthermore, the large volume of sludge generated increases treatment and transportation costs accordingly.

[0009] Therefore, there is an urgent need for a more environmentally friendly, economical, and efficient desulfurization wastewater treatment technology to solve the above problems. Summary of the Invention

[0010] (a) Technical problems to be solved

[0011] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a desulfurization wastewater clarification system. This system solves the technical problems of high reagent dependence, high operating costs, large amount of difficult-to-treat sludge, and complex process management in the traditional desulfurization wastewater treatment process by introducing pre-separation and three-stage physical clarification processes.

[0012] (II) Technical Solution

[0013] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0014] A desulfurization wastewater clarification system includes a pretreatment unit and a clarification unit. The pretreatment unit includes an absorption tower, a gypsum hydrocyclone, a dewatering kit, and a gypsum overflow tank. The absorption tower is connected to the gypsum hydrocyclone, and the gypsum hydrocyclone is connected to the gypsum overflow tank and the dewatering kit. The dewatering kit is connected to the clarification unit, and the clarification unit includes multi-stage sedimentation clarification tanks, which are respectively connected to the absorption tower, the dewatering kit, and / or the gypsum overflow tank.

[0015] In some embodiments, the basic unit includes a boiler, an electrostatic precipitator, and an induced draft fan. The boiler is connected to one end of the electrostatic precipitator, and the other end of the electrostatic precipitator is connected to the absorption tower via the induced draft fan. The absorption tower is connected to the chimney.

[0016] In some embodiments, the lower end of the absorption tower is connected to the gypsum hydrocyclone, the upper end of the gypsum hydrocyclone is connected to the upper end of the gypsum overflow tank, the lower end of the gypsum overflow tank is connected to the upper end of the absorption tower, and the lower end of the gypsum hydrocyclone is connected to the dewatering kit.

[0017] In some embodiments, the dehydration kit includes a gypsum dehydration vacuum belt kit, an air-water separator, a dehydration vacuum pump, and a wastewater tank. The lower end of the gypsum hydrocyclone is connected to the gypsum dehydration vacuum belt kit, the gypsum dehydration vacuum belt kit is connected to the air-water separator, one end of the air-water separator is connected to the dehydration vacuum pump, and the other end of the air-water separator is connected to the wastewater tank.

[0018] In some embodiments, the gypsum dehydration vacuum belt kit includes a first gypsum dehydration vacuum belt and a second gypsum dehydration vacuum belt, which are connected in parallel and are respectively connected to an air-water separator.

[0019] In some embodiments, the wastewater tank is connected to a clarification unit, which includes a primary clarification tank, a secondary clarification tank, a tertiary clarification tank, and a storage tank connected in descending order of height. The wastewater tank is connected to the primary clarification tank.

[0020] In some embodiments, the clarification unit further includes a sludge pump, one end of which is connected to the primary clarification tank, and the other end of which is connected to the first gypsum dewatering vacuum belt and the second gypsum dewatering vacuum belt.

[0021] In some embodiments, the clarification unit further includes a pit, the primary clarification tank is also connected to an absorption tower, and / or the primary clarification tank is connected to a gypsum overflow tank via the pit.

[0022] In some embodiments, the system further includes a gypsum concentration detector and a three-phase switch. The gypsum concentration detector is installed between the primary clarifier and the sludge pump. The gypsum concentration detector is located above the three-phase switch between the primary clarifier and the sludge pump and is close to the primary clarifier.

[0023] In some embodiments, the secondary clarifier is connected to the absorption tower, or the secondary clarifier is connected to the gypsum overflow tank via a pit, and a pump is located in the pit to transport gypsum to the gypsum overflow tank.

[0024] (III) Beneficial Effects

[0025] The desulfurization wastewater clarification system provided in this invention integrates a pretreatment unit and a clarification unit. Utilizing the synergistic effect of an absorption tower, gypsum hydrocyclone, dewatering kit, and gypsum overflow tank, it achieves effective pre-separation and multi-stage sedimentation clarification of desulfurization wastewater. In the pretreatment unit, the interconnected design of the absorption tower and gypsum hydrocyclone allows for effective separation of high-chlorine wastewater, reducing the difficulty of subsequent treatment. The application of the dewatering kit further reduces the solids content in the wastewater, laying a good foundation for the subsequent clarification process. The clarification unit employs a multi-stage sedimentation clarification tank design, which not only improves the removal efficiency of suspended solids but also allows for flexible adjustment of the functions of each clarification tank as needed, maximizing resource recovery. Overall, the system significantly reduces reagent usage, lowers operating costs, and significantly reduces sludge volume through the recycling and reuse of resources such as gypsum. It simplifies the process flow, improves system reliability and management efficiency, and achieves the goals of high efficiency, environmental protection, and economical treatment. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 The present invention relates to a desulfurization treatment system;

[0028] Figure 2 This is a current technology for desulfurization wastewater clarification systems;

[0029] [Explanation of Labels in the Attached Image]

[0030] 1. Basic unit; 2. Pretreatment unit; 3. Clarification unit; 4. Absorption tower; 5. Gypsum hydrocyclone; 6. Dewatering kit; 7. Gypsum overflow tank; 8. Boiler; 9. Electrostatic precipitator; 10. Exhaust fan; 11. Chimney; 12. Gypsum silo; 13. Triple tank; 14. Clarification tank; 15. Wastewater hydrocyclone; 16. Plate and frame filter press;

[0031] 31. Primary clarifier; 32. Secondary clarifier; 33. Tertiary clarifier; 34. Storage tank;

[0032] 35. Sludge pump; 36. Pit; 37. Gypsum concentration detector; 38. Three-phase switch;

[0033] 61. Plaster dehydration vacuum belt assembly; 62. Air-water separator; 63. Dehydration vacuum pump; 64. Wastewater tank;

[0034] 611. First gypsum dehydration vacuum belt; 612. Second gypsum dehydration vacuum belt. Detailed Implementation

[0035] The embodiments of this application will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application. This application can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0036] These embodiments are provided to make the application thorough and complete, and to fully express the scope of the application to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​illustrated in these embodiments should be interpreted as merely exemplary and not as limiting.

[0037] It should be noted that, in the description of this application, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationship, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0038] Furthermore, the terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. "Vertical" is not strictly vertical, but within the permissible margin of error. "Parallel" is not strictly parallel, but within the permissible margin of error. Terms such as "including" or "contains" mean that the element preceding the word encompasses the element listed after it, and do not exclude the possibility of encompassing other elements as well.

[0039] It should also be noted that, in the description of this application, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" 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 direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application depending on the specific circumstances. When a specific device is described as being located between a first device and a second device, an intermediary device may or may not be present between the specific device and the first or second device.

[0040] All terms used in this application have the same meaning as understood by one of ordinary skill in the art to which this application pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0041] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0042] See Figure 1 A desulfurization wastewater clarification system includes a pretreatment unit 2 and a clarification unit 3. The pretreatment unit 2 includes an absorption tower 4, a gypsum hydrocyclone 5, a dewatering kit 6, and a gypsum overflow tank 7. The absorption tower 4 is connected to the gypsum hydrocyclone 5, and the gypsum hydrocyclone 5 is connected to the gypsum overflow tank 7 and the dewatering kit 6. The dewatering kit 6 is connected to the clarification unit 3, and the clarification unit 3 includes a multi-stage sedimentation clarification tank, which is connected to the absorption tower 4, the dewatering kit 6, and / or the gypsum overflow tank 7, respectively.

[0043] By connecting the absorption tower 4 with the gypsum hydrocyclone 5, high-chlorine wastewater can be efficiently separated from the desulfurization slurry. This step significantly reduces the solids content of the wastewater entering subsequent treatment stages, simplifies subsequent clarification and treatment, and improves overall treatment efficiency.

[0044] The gypsum hydrocyclone 5 effectively separates slurry containing a high concentration of gypsum and directs it to the dewatering unit 6 for further processing. This process not only helps reduce the amount of sludge produced but also facilitates the recycling of gypsum.

[0045] Clarification Unit 3 employs a multi-stage sedimentation clarification tank design, progressively reducing the suspended solids content in wastewater through graded treatment to ensure that the final effluent meets higher water quality standards. The functions of each clarification tank can be flexibly adjusted as needed to adapt to different treatment requirements.

[0046] The interconnected design between the dewatering unit 6 and the clarification unit 3 allows for further removal of solids from the pre-treated wastewater and the recovery of valuable byproducts such as gypsum. This not only reduces waste generation but also maximizes resource utilization.

[0047] The system's design simplifies the traditionally complex desulfurization wastewater treatment process, reducing the need for multiple chemical reagents and thus lowering operational complexity and maintenance costs. Furthermore, the increased automation reduces the need for manual intervention, lowering labor costs.

[0048] Thanks to its modular design, the components are tightly connected and have clearly defined functions, which enhances the system's stability and reliability. For example, the gypsum hydrocyclone 5, the dewatering kit 6, and the multi-stage sedimentation and clarification tank work together to ensure the continuity and stability of the entire treatment process.

[0049] In summary, this desulfurization wastewater clarification system, by integrating the pretreatment unit 2 and the clarification unit 3, and utilizing the synergistic effect of the absorption tower 4, gypsum hydrocyclone 5, dewatering kit 6, and gypsum overflow tank 7, achieves the goal of efficient, environmentally friendly, and economical wastewater treatment, providing enterprises with a sustainable development solution.

[0050] See Figure 1 The basic unit 1 includes a boiler 8, an electrostatic precipitator 9, and an induced draft fan 10. The boiler 8 is connected to one end of the electrostatic precipitator 9, and the other end of the electrostatic precipitator 9 is connected to the absorption tower 4 through the induced draft fan 10. The absorption tower 4 is connected to the chimney 11.

[0051] Electrostatic precipitators 9 can efficiently capture fine particulate matter (such as dust and fly ash) in the flue gas emitted by boilers 8, with an efficiency typically exceeding 99%. This not only reduces the particulate load entering the subsequent wet desulfurization system but also significantly reduces the risk of wear and blockage to the desulfurization equipment.

[0052] After most of the particulate matter is removed by the electrostatic precipitator 9, the flue gas entering the absorption tower 4 is cleaner, which helps to improve the overall efficiency of the wet desulfurization process. Less particulate matter interference allows the desulfurizing agent to react more effectively with sulfur dioxide, thereby improving desulfurization efficiency.

[0053] The reasonable configuration of the induced draft fan 10 ensures smooth transmission of flue gas between various treatment stages. At the same time, by optimizing the air volume and pressure settings, unnecessary energy consumption can be reduced, energy can be effectively utilized, and operating costs can be further reduced.

[0054] See Figure 1 The lower end of the absorption tower 4 is connected to the gypsum hydrocyclone 5, the upper end of the gypsum hydrocyclone 5 is connected to the upper end of the gypsum overflow box 7, the lower end of the gypsum overflow box 7 is connected to the upper end of the absorption tower 4, and the lower end of the gypsum hydrocyclone 5 is connected to the dewatering kit 6.

[0055] The gypsum hydrocyclone 5 can efficiently separate the gypsum slurry accumulated at the bottom of the absorption tower 4, effectively removing solid particles from the wastewater. This not only reduces the suspended solids content entering subsequent treatment steps, but also facilitates further processing and recycling of gypsum.

[0056] The gypsum-rich slurry separated by the gypsum hydrocyclone 5 can be directly fed into the dewatering unit 6 for further processing, thereby achieving effective gypsum recycling. The recycled gypsum can be used in building materials or other industrial applications, maximizing resource utilization and reducing waste generation.

[0057] The design of connecting the upper end of the gypsum hydrocyclone 5 to the gypsum overflow tank 7 allows the cleaner liquid after preliminary separation to return to the absorption tower 4 to continue participating in the desulfurization reaction, reducing the overall load on the system and improving resource utilization. Simultaneously, this recycling mechanism also helps maintain the stability of the chemical reaction environment within the absorption tower 4.

[0058] The close coordination between the system's components ensures a smooth and efficient process from absorption tower 4 to the bottom gypsum treatment. This design reduces operational interruptions due to equipment failure or performance degradation, enhancing the system's stability and reliability.

[0059] See Figure 1 The dehydration kit 6 includes a gypsum dehydration vacuum belt kit 61, an air-water separator 62, a dehydration vacuum pump 63, and a wastewater tank 64. The lower end of the gypsum hydrocyclone 5 is connected to the gypsum dehydration vacuum belt kit 61, the gypsum dehydration vacuum belt kit 61 is connected to the air-water separator 62, one end of the air-water separator 62 is connected to the dehydration vacuum pump 63, and the other end of the air-water separator 62 is connected to the wastewater tank 64.

[0060] The gypsum dehydration vacuum belt kit 61 efficiently removes moisture from gypsum slurry, producing gypsum cakes with low moisture content (typically below 12%). This not only facilitates subsequent transportation and storage but also enhances the commercial value of gypsum as a by-product.

[0061] After being processed by the gypsum dehydration vacuum belt assembly 61, the separated water enters the wastewater tank 64. This wastewater can be further treated for reuse or discharged in compliance with standards, reducing its environmental impact. Furthermore, the design of the wastewater tank 64 facilitates centralized wastewater management and subsequent treatment steps.

[0062] The combined use of the air-liquid separator 62 and the dehydration vacuum pump 63 ensures the high efficiency of the dehydration process. The air-liquid separator 62 effectively separates air and liquid, preventing the vacuum pump from drawing in moisture, thereby protecting the equipment from damage, extending its service life, and improving the stability of system operation.

[0063] See Figure 1 The gypsum dehydration vacuum belt kit 61 includes a first gypsum dehydration vacuum belt 611 and a second gypsum dehydration vacuum belt 612. The first gypsum dehydration vacuum belt 611 and the second gypsum dehydration vacuum belt 612 are arranged in parallel. The first gypsum dehydration vacuum belt 611 and the second gypsum dehydration vacuum belt 612 are respectively connected to the gas-water separator 62.

[0064] By using a first gypsum dewatering vacuum belt 611 and a second gypsum dewatering vacuum belt 612 connected in parallel, the system can process more gypsum slurry simultaneously, thus significantly improving the overall processing capacity. This not only helps to cope with peak loads but also ensures that the system can still operate stably under high load conditions.

[0065] The parallel arrangement of two gypsum dehydration vacuum belts provides redundancy, ensuring system continuity and stability even if one belt fails or requires maintenance. This design reduces downtime due to single points of failure and improves overall system reliability.

[0066] Two vacuum belts for gypsum dewatering enable more efficient processing of gypsum slurry, ensuring more uniform and stable quality of gypsum cake. High-quality gypsum cake facilitates subsequent transportation, storage, and reuse, further enhancing the efficiency and value of resource recycling.

[0067] The parallel arrangement of two gypsum dehydration vacuum belts allows for maintenance and repair of individual belts without shutting down the machine, greatly simplifying the maintenance process, reducing downtime, and minimizing production disruption.

[0068] See Figure 1Wastewater tank 64 is connected to clarification unit 3. Clarification unit 3 includes a primary clarification tank 31, a secondary clarification tank 32, a tertiary clarification tank 33 and a storage tank 34 connected in descending order. Wastewater tank 64 is connected to primary clarification tank 31.

[0069] Through the design of multi-stage sedimentation and clarification tanks (primary clarifier 31, secondary clarifier 32, and tertiary clarifier 33), wastewater can undergo solid-liquid separation and clarification step by step. Each stage of the tank treats suspended solids of different particle sizes and densities, ensuring a gradual improvement in treatment efficiency and ultimately achieving highly efficient wastewater clarification.

[0070] In each stage of the clarification tank, solid particles and suspended solids in wastewater can be removed by physical methods without the need for chemical reagents. This not only reduces reagent costs but also avoids the risk of secondary pollution. For example, larger gypsum particles can be effectively separated in the primary clarification tank 31, facilitating subsequent recycling.

[0071] By using physical clarification methods instead of chemical reagents, the system significantly reduces reagent costs. Furthermore, the multi-stage clarification tank design reduces the workload of each tank, extending equipment lifespan and reducing maintenance and replacement costs, thereby further lowering overall operating costs.

[0072] Multi-stage clarification processes can more thoroughly separate solids from wastewater, reducing the amount of sludge produced. Compared to traditional methods, the total amount of sludge can be reduced by 95%, which not only lowers sludge disposal costs but also reduces the environmental burden.

[0073] Each stage of the clarifier can be flexibly adjusted in terms of function and operating parameters according to actual needs. For example, the primary clarifier 31 mainly settles large particles, the secondary clarifier 32 further removes fine particles, and the tertiary clarifier 33 can also perform final removal of suspended solids and water stabilization treatment. This flexibility makes the system easier to manage and operate, ensuring optimal treatment results.

[0074] After undergoing multi-stage clarification treatment, the wastewater quality becomes more stable, reaching higher purification standards. The clean water that finally enters storage tank 34 can be reused for purposes such as dust suppression spraying in the coal yard or ash humidification, achieving 100% wastewater reuse, significantly reducing the demand for external water resources, and minimizing the environmental impact of emissions.

[0075] This compact and direct connection simplifies the traditionally complex desulfurization wastewater treatment process, reducing intermediate steps and equipment requirements. For example, the wastewater tank 64 is directly connected to the primary clarifier 31, avoiding additional transportation and storage steps, simplifying the operation process, and reducing maintenance costs.

[0076] The close coordination between the components ensures a smooth and efficient treatment process from wastewater tank 64 to storage pool 34. This design reduces operational interruptions due to equipment failure or performance degradation, enhancing the stability and reliability of the system.

[0077] See Figure 1 The clarification unit 3 also includes a sludge pump 35. The primary clarification tank 31 is connected to one end of the sludge pump 35, and the other end of the sludge pump 35 is connected to the first gypsum dehydration vacuum belt 611 and the second gypsum dehydration vacuum belt 612 respectively.

[0078] The sludge pump 35 effectively transports the sludge (mainly gypsum) accumulated at the bottom of the primary clarifier 31 to the gypsum dewatering vacuum belt assembly 61 for further treatment. This design ensures that the sludge can be removed in a timely and efficient manner and proceed to the next stage of the treatment process.

[0079] By feeding gypsum-rich sludge into the gypsum dewatering vacuum belt assembly 61, the system can effectively recover and utilize gypsum. This not only reduces the amount of solid waste generated but also maximizes resource utilization and improves economic efficiency.

[0080] The design of the sludge pump 35 allows sludge to be quickly discharged from the primary clarifier 31, avoiding excessive accumulation of sludge in the tank, thereby reducing the workload and frequency of cleaning and maintenance.

[0081] The tight fit between the sludge pump 35 and the gypsum dewatering vacuum belt assembly 61 ensures continuous operation of the entire system. Even under high load conditions, it guarantees timely sludge treatment and avoids system failures or efficiency reductions caused by sludge accumulation.

[0082] Timely discharge of sludge can prevent it from damaging the primary clarifier 31 and other equipment, extend the service life of the equipment, and improve the reliability and stability of the system.

[0083] The sludge in the primary clarifier 31 is promptly discharged by the sludge pump 35, ensuring that the functions of each clarifier are fully utilized and improving the overall system efficiency. The primary clarifier 31 focuses on the settling of large particles, while the secondary and tertiary clarifiers 33 focus more on the removal of fine particles and suspended solids, thereby improving the water purification effect.

[0084] See Figure 1 The clarification unit 3 also includes a pit 36, and the primary clarification tank 31 can also be connected to the absorption tower 4, and / or the primary clarification tank 31 is connected to the gypsum overflow box 7 through the pit 36.

[0085] By connecting the primary clarifier 31 to the absorption tower 4 or the gypsum overflow tank 7 via the pit 36, flexible material allocation and recycling can be achieved. For example, the supernatant containing a small amount of gypsum can be returned to the absorption tower 4 through the pit 36 ​​to replenish the reactants in the absorption tower 4, increase the active components of the slurry, and enhance the desulfurization efficiency.

[0086] Returning a portion of the treated water from the primary clarifier 31 to the absorber 4 or the gypsum overflow tank 7 helps reduce water waste and maximizes the use of existing resources within the system, thereby lowering overall operating costs.

[0087] The design of the pit 36 ​​allows for the balancing of flow and load among different treatment units. For example, under high load conditions, a portion of the wastewater can be transferred from the primary clarifier 31 to the gypsum overflow tank 7 or other treatment units through the pit 36, preventing overload of individual units and ensuring the stable operation of the entire system.

[0088] The primary clarifier 31 is connected to other treatment units via the pit 36, allowing the material flow direction to be adjusted according to actual needs, thus maximizing the functionality of each treatment unit. For example, the primary clarifier 31 focuses on the settling of large particles, while the treated water is sent to other units via the pit 36 ​​for further clarification or reuse, improving overall treatment efficiency.

[0089] The treated water is returned to the absorption tower 4 or the gypsum overflow tank 7 through the pit 36, which reduces the amount of emissions to the external environment, reduces the impact on the environment, and meets strict environmental protection standards.

[0090] See Figure 1 The system also includes a gypsum concentration detector 37 and a three-phase switch 38. The gypsum concentration detector 37 is installed between the primary clarifier 31 and the sludge pump 35. The gypsum concentration detector 37 is located above the three-phase switch 38 between the primary clarifier 31 and the sludge pump 35 and is close to the primary clarifier 31.

[0091] The direction of the three-phase switch 38 is determined by setting the gypsum concentration threshold, thereby determining whether the material returns to the absorption tower 4, the gypsum overflow box 7, or the gypsum dehydration vacuum belt assembly 61.

[0092] The gypsum concentration detector 37 can monitor the gypsum concentration of the sludge in the primary clarifier 31 in real time and automatically adjust the direction of the three-phase switch 38 according to a preset threshold. This allows the system to flexibly select the optimal material flow direction according to actual operating conditions, ensuring that each processing unit can operate under optimal conditions.

[0093] When the gypsum concentration is low, the sludge can be returned to the absorption tower 4 or the gypsum overflow tank 7. Conversely, when the gypsum concentration is high, it is directly sent to the gypsum dewatering vacuum belt assembly 61 for further treatment and recycling. This intelligent allocation method maximizes the utilization of resources within the system. Different treatment paths are selected based on different gypsum concentrations, ensuring that the function of each treatment unit is fully utilized. For example, high-concentration gypsum can directly enter the dewatering stage, while low-concentration gypsum can be first returned to increase its concentration before subsequent treatment.

[0094] Through real-time monitoring and intelligent allocation, the system effectively prevents equipment blockages or other malfunctions caused by excessive gypsum concentration. Simultaneously, rational material allocation extends the service life of critical equipment and improves system reliability and stability. If a processing unit malfunctions or requires maintenance, the material can be temporarily transferred to another unit for processing by adjusting the direction of the three-phase switch 38, reducing downtime and enhancing the system's emergency response capabilities.

[0095] The design of the gypsum concentration detector 37 and the three-phase switch 38 facilitates automated control, reduces the need for manual intervention, and improves the overall system's automation and management levels.

[0096] Because the system can automatically adjust the material flow direction according to the gypsum concentration, operators can more easily monitor and manage the entire system, ensuring that each processing step is in optimal condition, thereby improving the system's management efficiency.

[0097] See Figure 1 The secondary clarifier 32 is connected to the absorption tower 4, or the secondary clarifier 32 is connected to the gypsum overflow tank 7 through the pit 36. The pit 36 ​​contains a pump body to transport gypsum to the gypsum overflow tank 7.

[0098] By recirculating the treated water in the secondary clarifier 32 back to the absorber 4 or the gypsum overflow tank 7, flexible material allocation and recycling can be achieved. For example, the supernatant containing a small amount of gypsum can be recirculated back to the absorber 4 through the pit 36 ​​to replenish the reactants in the absorber 4, increase the active components of the slurry, and enhance the desulfurization efficiency.

[0099] Returning a portion of the treated water from the secondary clarifier 32 to the absorber 4 or the gypsum overflow tank 7 helps reduce water waste and maximizes the use of existing resources within the system, thereby reducing overall operating costs.

[0100] The tertiary clarifier 33 is mainly used for storage.

[0101] By replacing chemical precipitation with three-stage physical clarification, sludge resources are recycled in stages, eliminating the use of chemicals.

[0102] Primary clarification (solid-liquid separation): The high-chlorine wastewater enters the primary clarification tank 31, where it settles naturally. At the same time, the sludge rich in gypsum at the bottom is discharged to the dewatering conveyor belt to be mixed with the dewatered gypsum and transported off-site (moisture content <12%).

[0103] Secondary clarification (internal recycling): The supernatant from the primary clarifier 31 flows into the secondary clarifier 32 for secondary sedimentation. The fine sludge containing some gypsum that settles out is intermittently discharged into the ditch and returned to the desulfurization system.

[0104] Tertiary clarification (reuse after settling): The solids content of the secondary effluent is less than 1%, and it finally enters a 3000 cubic meter desulfurization wastewater buffer tank for settling. The suspended solids in the wastewater are significantly reduced. When needed, the clear supernatant is directly reused for dust suppression spraying in the coal yard or for ash humidification, achieving 100% wastewater reuse. The small amount of sludge that settles at the bottom of the desulfurization wastewater buffer tank is cleaned regularly.

[0105] This desulfurization wastewater clarification system achieves end-to-end optimization from pretreatment to final resource recovery through a highly coordinated design. First, the absorption tower 4 and gypsum hydrocyclone 5 work in close coordination to effectively separate high-chlorine wastewater, reducing the difficulty of subsequent treatment. The gypsum hydrocyclone 5 further sends the gypsum-rich slurry into the dewatering kit 6 for efficient dewatering, and the resulting gypsum cake can be used for resource recovery. The primary clarifier 31, secondary clarifier 32, and tertiary clarifier 33 sequentially treat the wastewater, gradually removing suspended solids and optimizing water quality to ensure the quality of the final effluent. The placement of the sump 36 and pumps allows for flexible material allocation between treatment units, maximizing resource utilization and maintaining system load balance. The introduction of the gypsum concentration detector 37 and three-phase switch 38 dynamically adjusts the material flow direction based on real-time monitoring data, ensuring that each treatment step operates under optimal conditions. Furthermore, the entire system simplifies operation through automated control and a compact design, reducing the need for manual intervention and improving management efficiency and system stability. This highly coordinated design not only improves treatment efficiency and reduces operating costs but also significantly reduces environmental impact.

[0106] This application connects the gas-liquid separator 62 directly to the wastewater tank 64, reducing the solids content of the wastewater from 5% to 2%. The plate and frame filter press 16 and wastewater hydrocyclone 15, which have high failure rates, are eliminated, significantly reducing the failure rate, as 90% of failures in the enterprise occur in these two devices. The tertiary clarifier 33, also called the desulfurization wastewater buffer tank, reduces sludge by 95%. The wastewater in this tank can be directly used for ash removal and humidification or dust suppression spraying in coal yards, and contains very little sludge. Because of the low sludge content, the tertiary clarifier 33 only needs to be cleaned once every 3 years.

[0107] Comparative Example 1

[0108] In the desulfurization wastewater raw water, calcium hydroxide, organic sulfur, flocculant (polyferric chloride), and coagulant aid (PAM) are added to the triplet tank 13 and repeatedly stirred and mixed. The mixed wastewater raw water enters the clarifier tank 14 for neutralization, flocculation, and sedimentation. The supernatant of the clarifier tank 14 is used as wastewater, and the sediment at the bottom of the clarifier tank 14 is used as sludge for sludge dewatering treatment.

[0109] The system process is as follows:

[0110]

[0111] In existing technologies, excessive use of chemicals can cause secondary pollution. Desulfurization wastewater has a complex composition, requiring the addition of various chemical agents (such as calcium hydroxide, organic sulfur, flocculant polyferric chloride, coagulant PAM, and hydrochloric acid) for neutralization, precipitation, and heavy metal removal. However, excessive use of these agents can lead to residue problems, increase the difficulty of subsequent sludge treatment, and may cause secondary pollution risks such as pH imbalance and salt accumulation in the water body. Furthermore, the cost of these chemicals accounts for a large proportion of the total treatment cost, and excessive addition significantly reduces economic efficiency.

[0112] The sludge production is enormous. The desulfurization wastewater is separated from the slurry in absorber 4, and 95% of the sediment at the bottom of clarifier 14 is gypsum from the slurry in absorber 4. Because the gypsum in this sludge is treated as solid waste, it leads to the generation of a large amount of solid waste, increasing disposal costs and environmental burden.

[0113] High operating costs. The traditional "three-compartment 13" process relies on continuous dosing of chemicals and the operation of precision dosing equipment, involving chemical costs (10 yuan / ton of desulfurization wastewater), electricity consumption (2.5 yuan / ton of desulfurization wastewater), maintenance costs (11 yuan / ton of desulfurization wastewater), and sludge disposal costs (10 yuan / ton of desulfurization wastewater). The overall operating costs are extremely high, which affects economic benefits.

[0114] The process presents complex technological challenges and management difficulties. It encompasses multiple stages from wastewater pretreatment to final sludge dewatering, including neutralization, flocculation, and clarification, requiring multi-stage equipment to operate in series. Precise control of parameters at each stage (e.g., pH value, chemical dosage) is essential, resulting in low operational tolerance and susceptibility to equipment failure. The lengthy process not only occupies significant space but also increases the difficulty of automation control, raises the cost of manual inspection and maintenance, and limits overall operational efficiency.

[0115] The labor intensity for workers is high. The plate and frame filter press 16 used in the sludge treatment process requires manual shoveling of sludge, with at least two operators per shift, resulting in high labor intensity. The plate and frame filter press experiences frequent malfunctions, requiring maintenance on average every two days. Furthermore, the large volume of sludge production necessitates regular transport by specialized vehicles. Due to the high solids content of the slurry in the absorption tower 4, the wastewater hydrocyclone 15 suffers from severe clogging, requiring frequent cleaning of the clogged hydrocyclone holes to maintain the normal operation of the wastewater discharge system.

[0116] See Figure 2 This is a desulfurization wastewater treatment system in our company's previous technology. The gas-liquid separator 62 is connected to the gypsum overflow tank 7, the gypsum overflow tank 7 is connected to the wastewater hydrocyclone 15, the wastewater hydrocyclone 15 is connected to the wastewater tank 64, the wastewater tank 64 is first connected to the triple tank 13, and various chemicals are added to the triple tank 13 to treat sludge and wastewater. The treated wastewater enters the clarification tank 14, and a plate and frame filter press 16 is installed inside the clarification tank 14. The clarification tank 14 is connected to the wastewater tank.

[0117] The wastewater hydrocyclone 15 uses centrifugal force to rapidly separate the incoming slurry. Heavier solid particles (such as gypsum) are thrown towards the outer wall due to their greater inertia and move downwards along the wall, eventually being discharged from the bottom; while the lighter liquid concentrates in the central area and flows upwards, being discharged through the top outlet. Due to the cyclone, the solid content in the wastewater tank 64 is at least 5%.

[0118] By implementing measures such as pre-separation and three-stage clarification and reuse, the high cost, high pollution and low efficiency of traditional processes have been systematically overcome, achieving the goal of "zero chemical addition, zero discharge and full resource reuse" in desulfurization wastewater treatment, and providing a replicable technical and management model for enterprises' green transformation.

[0119] (I) Economic Results

[0120] Traditional sludge disposal is costly and poses environmental risks. The new technology sorts and reuses gypsum from the sludge in the production chain, achieving "waste-to-waste treatment" and resource value-added. After tertiary clarification, the suspended solids in the wastewater are around 60 mg / L, eliminating the need for chemical additions and reducing chemical costs to zero. The gypsum in the sludge is recovered or utilized, reducing sludge transportation volume by 95%. The process is simplified, equipment reliability is significantly improved, workload is greatly reduced, and nine workers are saved.

[0121] After adopting this technology, the operating cost per ton of desulfurization wastewater decreased from 36.5 yuan to 2.85 yuan. The power plant generates 60,000 tons of desulfurization wastewater annually, resulting in a total saving of 2.019 million yuan in operating costs.

[0122] The table below compares the operating costs of this application and Comparative Example 1.

[0123]

[0124] (II) Environmental Achievements

[0125] Primary sludge for building materials: The gypsum-rich sludge from the primary clarifier tank 31 is mixed with dewatered gypsum and then transported off-site for use in the building materials industry. This increases gypsum production and saves the cost of transporting gypsum from the sludge separately.

[0126] Secondary sludge internal circulation: Sludge containing a small amount of gypsum is returned to the desulfurization system to replenish the reactive components of the absorption tower 4 and improve the slurry quality.

[0127] The third-level wastewater harmless utilization: the desulfurization wastewater that has been left to stand in the final desulfurization wastewater buffer tank is used for dust suppression spraying in the coal yard or for ash humidification, increasing the wastewater reuse rate to 100% and significantly reducing ecological risks.

[0128] (III) Management Effectiveness

[0129] The new technology process is simple and reliable, with no equipment prone to failure. Only three sludge scrapers and two conveying pumps remain in stable operation. Full-process automated control and standardized management increase the operational fault tolerance rate by 90%. Team-based collaborative inspections and training assessments ensure operational stability, and fault response time is reduced to 30 minutes. Wastewater reuse rate reaches 100%, COD, SS and other pollutant emissions decrease by 50%, eliminating the risk of chemical residues. It simultaneously achieves economic, environmental, and efficient management goals, providing a replicable model for enterprises' green transformation.

[0130] In this application, because gypsum settles faster than sludge in the primary clarifier 31, gypsum settles first and can be transported to the gypsum dewatering vacuum conveyor belt. Over time, some sludge mixes with the gypsum, exceeding a threshold. The relevant switches are then closed, and the remaining sludge-water flows into the secondary clarifier 32. The secondary clarifier 32 mainly contains a mixture of sludge and gypsum, and therefore, it is transported to the absorption tower 4. The tertiary clarifier 33 contains the actual sludge, with a small amount settling at the bottom, requiring cleaning every three years. Through this graded sludge treatment, this design reduces sludge by 95%, eliminating the need for a plate and frame filter press 16.

[0131] The plate and frame filter press 16 achieves solid-liquid separation by applying pressure to expel liquid from the sludge. It utilizes a set of alternately arranged filter plates and frames to form multiple filter chambers, which are filled with the sludge to be treated. When hydraulic pressure is applied, water is discharged through the filter cloth, while solid particles are trapped on the filter cloth to form a sludge cake. This application utilizes multi-stage sedimentation technology, and the water from the preceding wastewater tank 64 contains relatively little sludge, resulting in very little sludge settling at the end, thus eliminating the need for the plate and frame filter press 16.

[0132] Furthermore, this application proposes a method for alternating the use of two or more absorption towers 4 (such as absorption towers 1 and 2 4) for desulfurization and gypsum separation. For example, while absorption tower 1 4 is undergoing desulfurization, absorption tower 2 4 focuses on gypsum separation and discharge. This alternating operation ensures that the gypsum concentration in each absorption tower 4 remains within a relatively ideal range, avoiding system blockage or other problems caused by excessively high gypsum concentration. The high-chlorine filtrate with a solids content of approximately 2% is drawn from the bottom of the gas-liquid separator 62 at the inlet of the dehydration vacuum pump 63 and discharged separately as raw desulfurization wastewater to the wastewater tank 64. Simultaneously, the gypsum slurry at the bottom of absorption tower 4 is sent to a vacuum belt dewatering machine for dehydration treatment, forming gypsum cakes with low moisture content. By alternating the use of different vacuum belt dewatering machines, continuous and efficient operation of the equipment can be ensured, and downtime for maintenance can be reduced.

[0133] The reason why the wastewater hydrocyclone 15 and plate and frame filter press 16 can be omitted in this application is mainly due to the innovative pre-separation technology and three-stage physical clarification process adopted by the system, which achieves efficient, economical and environmentally friendly solid-liquid separation and sludge treatment. By combining cross-plaster removal process with vacuum belt dewatering equipment, solid particles in high-chlorine wastewater can be efficiently removed in the pre-separation stage, and gypsum can be directly recovered, replacing the preliminary solid-liquid separation function of wastewater hydrocyclone 15. After the water entering the wastewater tank 64 is treated by the vacuum belt dewatering equipment, the solid content is significantly reduced (usually below 2%), so there is no need for an additional wastewater hydrocyclone 15. Specifically:

[0134] A. Synergistic effect of key equipment

[0135] Gypsum dehydration vacuum belt kit 61: efficiently removes water from gypsum slurry to form gypsum cakes with low moisture content (usually below 12%). These gypsum cakes can be directly used in building material production or other industrial applications, maximizing resource utilization.

[0136] Air-liquid separator 62: Effectively separates air and liquid, prevents the vacuum pump from sucking in moisture, protects the equipment from damage, and ensures the stability and reliability of the dehydration process.

[0137] Dehydration vacuum pump 63: Provides the necessary negative pressure to ensure the smooth progress of the dehydration process, thereby ensuring the efficient operation of the gypsum dehydration vacuum belt assembly 61.

[0138] Wastewater tank 64: Stores pre-treated wastewater with low solids content to prepare for further clarification treatment and ensure more stable and reliable water quality in subsequent treatment steps.

[0139] B. Design of the three-stage sedimentation and clarification tank 14

[0140] The three-stage sedimentation and clarification tank 14 progressively treats suspended solids in wastewater, purifying them step by step from large particles to fine particles, ensuring the quality of the final effluent while reducing sludge production. The primary clarification tank 31 mainly treats larger solid particles, discharging gypsum-rich sludge and sending it to dewatering equipment for further treatment; the secondary clarification tank 32 further removes finer particles; and the tertiary clarification tank 33 completes the final removal of fine suspended solids and water stabilization treatment.

[0141] C. Intelligent material distribution

[0142] The intelligent design of the gypsum concentration detector 37 and the three-phase switch 38 can automatically adjust the material flow direction according to the real-time monitored gypsum concentration, maximizing resource utilization and further reducing the demand on the plate and frame filter press 16. When the gypsum concentration is high, the sludge is sent to the gypsum dewatering vacuum belt assembly 61 for dewatering; when the gypsum concentration is low, the sludge can be returned to the absorption tower 4 or the gypsum overflow tank 7 to replenish the reactive components.

[0143] This solution comprehensively optimizes the desulfurization wastewater treatment process through innovative pre-separation of wastewater combined with three-stage clarification technology, resulting in significant environmental and economic benefits:

[0144] Eliminating chemical dependence and avoiding secondary pollution: This system achieves the goal of zero chemical addition during wastewater treatment, effectively avoiding the risk of secondary pollution caused by chemical residues, and ensuring that the treated water is purer and safer.

[0145] Utilizing gypsum resources reduces sludge volume: By recycling and reusing the gypsum component in sludge, not only is the amount of solid waste generated reduced, but sludge treatment costs are also lowered. Compared with traditional methods, the total amount of sludge is reduced by 95%, greatly alleviating the environmental burden.

[0146] Significantly reduced operating costs: This solution drastically reduces reagent costs, and due to process simplification and improved equipment efficiency, electricity consumption, labor costs, and sludge disposal costs are also effectively controlled. Overall, the cost of the entire wastewater treatment process is significantly reduced.

[0147] Simplified process flow and reduced maintenance workload: The optimized process flow reduces several complex steps, lowers the risk of equipment failure, makes the system more automated and easier to operate, thereby reducing the need for manual intervention, reducing manpower requirements by 90%.

[0148] Enhanced system reliability and security: Advanced technologies and designs improve system stability and reliability, reduce unexpected downtime and maintenance frequency, and ensure long-term stable operation.

[0149] Significant environmental benefits and reduced pollution: Through the above-mentioned improvement measures, this solution not only reduces the impact of wastewater discharge on the environment, but also greatly reduces the amount of sludge, promotes the green transformation of enterprises, and contributes to the achievement of sustainable development goals.

[0150] In summary, this solution, by integrating pre-separation and three-stage physical clarification technologies, successfully solves many problems existing in traditional desulfurization wastewater treatment methods, achieving the goal of efficient, economical, and environmentally friendly wastewater treatment, and has significant application value and promotion potential.

[0151] The embodiments of this application have now been described in detail. To avoid obscuring the concept of this application, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0152] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any manner.

Claims

1. A desulfurization wastewater clarification system, characterized in that, The system includes a pretreatment unit (2) and a clarification unit (3). The pretreatment unit (2) consists of an absorption tower (4), a gypsum hydrocyclone (5), a dewatering kit (6), and a gypsum overflow tank (7). The absorption tower (4) is connected to the gypsum hydrocyclone (5), the gypsum hydrocyclone (5) is connected to the gypsum overflow tank (7) and the dewatering kit (6), and the lower end of the gypsum overflow tank (7) is connected to the upper end of the absorption tower (4). The dehydration kit (6) includes a gypsum dehydration vacuum belt kit (61), a gas-liquid separator (62), a dehydration vacuum pump (63), and a wastewater tank (64). The lower end of the gypsum hydrocyclone (5) is connected to the gypsum dehydration vacuum belt kit (61), the gypsum dehydration vacuum belt kit (61) is connected to the gas-liquid separator (62), one end of the gas-liquid separator (62) is connected to the dehydration vacuum pump (63), and the other end of the gas-liquid separator (62) is connected to the wastewater tank (64). The wastewater tank (64) is connected to the clarification unit (3), which includes a primary clarification tank (31), a secondary clarification tank (32), a tertiary clarification tank (33), a storage tank (34), a sludge pump (35), a pit (36), a gypsum concentration detector (37), and a three-phase switch (38). The primary clarifier (31), secondary clarifier (32), tertiary clarifier (33) and storage tank (34) are connected in descending order, and the wastewater tank (64) is connected to the primary clarifier (31); The primary clarifier (31) is connected to one end of the sludge pump (35), and the other end of the sludge pump (35) is connected to the gypsum dewatering vacuum belt assembly (61). The gypsum concentration detector (37) is installed between the primary clarifier (31) and the sludge pump (35). The gypsum concentration detector (37) is located above the three-phase switch (38) between the primary clarifier (31) and the sludge pump (35) and is close to the primary clarifier (31). The gypsum concentration detector (37) is used to monitor the gypsum concentration of sludge in the primary clarifier (31) in real time and automatically adjust the direction of the three-phase switch (38) according to the preset threshold. When the gypsum concentration is low, the sludge is returned to the absorption tower (4) or the gypsum overflow tank (7). When the gypsum concentration is high, the sludge is sent to the gypsum dewatering vacuum belt assembly (61) for further treatment and recycling. The secondary clarifier (32) is connected to the absorption tower (4), or the secondary clarifier (32) is connected to the gypsum overflow box (7) through the pit (36).

2. The desulfurization wastewater clarification system according to claim 1, characterized in that, The system includes a basic unit (1), which includes a boiler (8), an electrostatic precipitator (9) and an induced draft fan (10). The boiler (8) is connected to one end of the electrostatic precipitator (9), and the other end of the electrostatic precipitator (9) is connected to the absorption tower (4) through the induced draft fan (10). The absorption tower (4) is connected to the chimney.

3. The desulfurization wastewater clarification system according to claim 1, characterized in that, The lower end of the absorption tower (4) is connected to the gypsum hydrocyclone (5), the upper end of the gypsum hydrocyclone (5) is connected to the upper end of the gypsum overflow box (7), and the lower end of the gypsum hydrocyclone (5) is connected to the dewatering kit (6).

4. The desulfurization wastewater clarification system according to claim 3, characterized in that, The lower end of the gypsum hydrocyclone (5) is connected to the gypsum dehydration vacuum belt assembly (61).

5. The desulfurization wastewater clarification system according to claim 4, characterized in that, The gypsum dehydration vacuum belt assembly (61) includes a first gypsum dehydration vacuum belt (611) and a second gypsum dehydration vacuum belt (612). The first gypsum dehydration vacuum belt (611) and the second gypsum dehydration vacuum belt (612) are connected in parallel. The first gypsum dehydration vacuum belt (611) and the second gypsum dehydration vacuum belt (612) are respectively connected to the gas-water separator (62).

6. The desulfurization wastewater clarification system according to claim 5, characterized in that, The other end of the sludge pump (35) is connected to the first gypsum dehydration vacuum belt (611) and the second gypsum dehydration vacuum belt (612), respectively.

7. The desulfurization wastewater clarification system according to claim 6, characterized in that, The primary clarifier (31) is also connected to the absorption tower (4), and / or the primary clarifier (31) is connected to the gypsum overflow tank (7) through the pit (36).

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