A treatment system for high-salt, high-COD pesticide wastewater

Abstract

This invention provides a treatment system for high-salt, high-COD pesticide wastewater. Through the efficient combination of multi-effect forced circulation evaporation and cyclone flash crystallization, it significantly reduces system energy consumption and improves salt crystallization efficiency. The design, combining a multiphase ozone catalyst and a high-efficiency ozone reaction tower, achieves efficient degradation of recalcitrant organic matter in the evaporation condensate, improving ozone utilization and COD removal rates. The overall modular integrated design not only saves floor space but also enhances the automation level and operational stability of the equipment, making it particularly suitable for the efficient, stable, and compliant treatment of high-salt, high-COD wastewater from pesticide production enterprises.

Description

Technical Field

[0001] This utility model relates to the field of environmental engineering technology, and in particular to a treatment system for high-salt, high-COD pesticide wastewater. Background Technology

[0002] High-salinity, high-COD wastewater generated during the production of pesticide intermediates has become a key and challenging issue in the field of industrial wastewater treatment. This type of wastewater typically contains high concentrations of inorganic salts (such as sodium chloride and sodium sulfate) and recalcitrant organic pollutants (such as benzene compounds and heterocyclic compounds), characterized by high salinity, high toxicity, and poor biodegradability. Traditional biological treatment methods are difficult to apply directly, and while physicochemical methods have some effect, they are often costly, have long processes, and poor stability.

[0003] Currently, the industry mostly adopts a combined process route of "pretreatment-evaporation concentration-advanced oxidation-deep treatment," but in practical engineering applications, many problems still exist: evaporation units are prone to scaling and clogging, resulting in high energy consumption; traditional advanced oxidation units have low reaction efficiency and low ozone utilization; each process unit is set up independently, resulting in low integration, large footprint, insufficient automation, and complex operation and management. Furthermore, existing equipment often lacks an efficient synergistic removal mechanism for recalcitrant organic matter in high-salinity wastewater, leading to large fluctuations in effluent quality and difficulty in consistently meeting the requirements of the "Integrated Wastewater Discharge Standard" (GB 8978-1996).

[0004] Therefore, there is an urgent need to develop a highly integrated, low-energy-consumption, high-efficiency, and stable treatment equipment specifically for high-salt and high-COD pesticide wastewater to solve the problems of poor process coupling, high energy consumption, complex operation, and unstable effluent quality in existing technologies. Utility Model Content

[0005] The purpose of this invention is to provide a treatment system for high-salt, high-COD pesticide wastewater to solve the problems existing in the prior art.

[0006] To achieve the above objectives, this utility model provides the following solution: This utility model provides a treatment system for high-salt, high-COD pesticide wastewater, comprising: The pretreatment unit includes a raw water storage tank, a pH adjustment tank, a self-electrolysis coagulation and flocculation reaction tank, an inclined plate sedimentation tank, and a pretreated effluent tank connected in sequence. A multi-effect evaporation and salt precipitation unit includes a first-effect forced circulation evaporator and a second-effect forced circulation evaporator connected in series. The inlet of the first-effect forced circulation evaporator is connected to the outlet of the pre-treated water tank. The first-effect forced circulation evaporator is connected to a first-effect condensate tank. The second-effect forced circulation evaporator is connected to a second-effect condensate tank. Both the first-effect condensate tank and the second-effect condensate tank are connected to a mixed condensate tank. The second-effect forced circulation evaporator is connected to a cyclone flash crystallizer and a centrifuge. An advanced oxidation degradation unit includes a multiphase ozone catalytic oxidation reaction tower connected to the mixed condensate tank. The multiphase ozone catalytic oxidation reaction tower is equipped with a microporous titanium aeration disc connected to an ozone generator. The multiphase catalytic ozone reaction tower is also connected to an exhaust gas destroyer. The advanced treatment and discharge unit includes a neutralization sedimentation tank, which is connected to the multiphase ozone catalytic oxidation reaction tower and the multi-media filter. The multi-media filter is connected to the clear water discharge tank. The intelligent electrical control cabinet is electrically connected to each unit and is used for centralized control and monitoring.

[0007] Preferably, the secondary steam outlet of the first-effect forced circulation evaporator is connected to the heating chamber inlet of the second-effect forced circulation evaporator, and the concentrated brine outlet of the second-effect forced circulation evaporator is connected to the inlet of the vortex flash crystallizer.

[0008] Preferably, the bottom outlet of the cyclone flash crystallizer is connected to the centrifuge, the solid outlet of the centrifuge is connected to the packaging machine, and the liquid outlet is returned to the pretreatment outlet tank through a pipeline.

[0009] Preferably, the multiphase ozone catalytic oxidation reaction tower is filled with multiphase aluminum-based ozone catalyst packing, and the bottom of the tower is provided with the microporous titanium aeration disc, which is connected to the ozone generator.

[0010] Preferably, the pretreatment unit is further provided with a dosing device and a sludge thickening tank. The dosing device includes an acid tank, an alkali tank, a coagulant tank, and a flocculant tank, which are respectively connected to the pH adjustment tank and the self-electrolytic coagulation and flocculation reaction tank via metering pumps.

[0011] Preferably, the multi-media filter includes a quartz sand layer and an activated carbon layer.

[0012] Preferably, the intelligent electrical control cabinet integrates a PLC controller, a touch screen, a pH sensor, a temperature sensor, a pressure sensor, and a liquid level sensor to achieve automatic control and remote monitoring.

[0013] The present invention achieves the following beneficial technical effects compared to the prior art: This invention provides a treatment system for high-salt, high-COD pesticide wastewater. Through the efficient combination of multi-effect forced circulation evaporation and cyclone flash crystallization, it significantly reduces system energy consumption and improves salt crystallization efficiency. The design of a multiphase ozone catalytic oxidation reaction tower achieves efficient degradation of recalcitrant organic matter in the evaporation condensate, improving ozone utilization and COD removal rates. The overall modular integrated design not only saves floor space but also enhances the automation level and operational stability of the equipment, making it particularly suitable for the efficient, stable, and compliant treatment of high-salt, high-COD wastewater from pesticide production enterprises. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the structure of the treatment system for high-salt, high-COD pesticide wastewater provided by this utility model. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] The purpose of this invention is to provide a treatment system for high-salt, high-COD pesticide wastewater to solve the problems existing in the prior art.

[0018] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] Example 1: This embodiment provides a treatment system for high-salt, high-COD pesticide wastewater, such as... Figure 1 As shown, the system adopts a modular integrated design, including a pretreatment unit 1, a multi-effect evaporation and salt precipitation unit 2, an advanced oxidation degradation unit 3, a deep treatment and emission unit 4, and an intelligent electrical control cabinet 5 connected in sequence.

[0020] Specifically, the pretreatment unit 1 includes a raw water storage tank 11, a pH adjustment tank 12, a self-electrolytic coagulation and flocculation reaction tank 13, an inclined plate sedimentation tank 14, and a pretreated effluent tank 15. The raw water storage tank 11 is connected to the plant's wastewater pipeline at its inlet, and its outlet is connected to the pH adjustment tank 12 via a booster pump. The pH adjustment tank 12 is equipped with a mechanical stirrer and an online pH sensor. Its dosing port is connected to an acid tank (e.g., a 30% hydrochloric acid solution) and an alkali tank (e.g., a 30% sodium hydroxide solution) via metering pumps to precisely adjust the wastewater pH to 6.5-7.5. The pH-adjusted wastewater flows by gravity into the self-electrolytic coagulation and flocculation reaction tank 13, which is divided into two compartments: the front compartment is the coagulation zone, where polyaluminum chloride (PAC) coagulant is added; the rear compartment is the flocculation zone, where polyacrylamide (PAM) flocculant is added. Both reaction tanks are equipped with low-speed stirrers with speeds of 100 r / min and 40 r / min, respectively. The subsequent inclined plate sedimentation tank 14 is made of stainless steel with an inclination angle of 60°. The effective sedimentation area is determined according to the treatment volume (e.g., designed for 10 m³ / h) and is used to achieve sludge-water separation. The supernatant enters the pretreatment effluent tank 15, and the bottom sludge is periodically discharged into the sludge thickening tank 16. The pretreatment effluent tank 15 is equipped with a level controller to link the feed pumps of subsequent units.

[0021] Furthermore, the multi-effect evaporation and salt precipitation unit 2 is one of the core components of this system, mainly comprising a first-effect forced circulation evaporator 21 and a second-effect forced circulation evaporator 22. Wastewater from the pretreated effluent tank 15 is fed into the first-effect forced circulation evaporator 21 via a corrosion-resistant feed pump (such as a fluoroplastic pump). The first-effect forced circulation evaporator 21 is made of 316L stainless steel, with an operating temperature controlled at 85-95℃, and its heat source is live steam (0.3MPa). The secondary steam generated in the first effect (approximately 80℃) serves as the heat source for the second-effect forced circulation evaporator 22, whose operating temperature is controlled at 70-75℃, creating a good thermal gradient and effectively reducing steam consumption. The concentrated brine (with a salt concentration close to saturation) discharged from the second-effect forced circulation evaporator 22 enters the cyclone flash crystallizer 23, where it is rapidly flash-cooled under vacuum conditions, promoting the crystallization and precipitation of salts (mainly sodium chloride and sodium sulfate). The crystallization slurry enters a horizontal screw discharge centrifuge 24 for solid-liquid separation. The separated solid salts are packaged by a baler and can be transported for disposal. The centrifugal mother liquor is returned to the pretreatment effluent tank 15 for reprocessing, realizing the resource utilization of salts and closed-loop treatment of wastewater. The condensate from the first and second effects is collected in the first-effect condensate tank 25 and the second-effect condensate tank 26, respectively, and finally flows into the mixed condensate tank 27. Although most of the salts have been removed from this mixed condensate, it still contains a low concentration of recalcitrant organic matter (COD approximately 200-500 mg / L), requiring further treatment in subsequent units.

[0022] Furthermore, the advanced oxidation degradation unit 3 is used for the deep degradation of recalcitrant organic matter in the condensate. Water in the mixed condensate tank 27 is pumped into the top of the multiphase ozone catalytic oxidation reaction tower 31 via a booster pump. This reaction tower is a vertical packed tower made of 316L stainless steel and filled with multiphase aluminum-based ozone catalyst packing material. The packing material has a particle size of Φ4-6mm and a specific surface area greater than 300m² / g, providing abundant catalytic active sites. Ozone gas (concentration of approximately 100mg / L) generated by the ozone generator 32 (output adjustable according to water volume, such as 2kg / h) is injected into the tower through a microporous titanium aeration disc 33 (pore size 5-10μm) at the bottom, where it is thoroughly mixed and contacted with the wastewater flowing upwards. Under the action of the multiphase aluminum-based ozone catalyst, ozone and the highly efficient catalytic decomposition of ozone to produce hydroxyl radicals (·OH) with extremely strong oxidizing power non-selectively oxidize and decompose organic matter into CO2, H2O, and small molecule inorganic substances, achieving a COD removal rate of over 70%. Unreacted trace amounts of ozone exhaust gas are discharged from the top of the tower and safely discharged after being treated by the thermal catalytic exhaust gas destroyer 34.

[0023] Furthermore, the advanced treatment and discharge unit 4 ensures that the final effluent fully and consistently meets standards. The effluent, after advanced oxidation treatment, flows by gravity into the neutralization sedimentation tank 41. A small amount of alkaline solution (such as NaOH solution) is added to adjust the pH to 6-9. If necessary, a trace amount of flocculant is added to precipitate any trace metal hydroxides that may be present. The supernatant is pumped into a multi-media filter 42, which is sequentially filled with quartz sand (0.5-1.2 mm particle size) and activated carbon (1.5-2.0 mm particle size) to further remove residual trace suspended solids and color, ensuring the sensory indicators of the effluent. Finally, the clear water flows into the clear water discharge tank 43, where COD, pH, and other indicators are monitored online. Once standards are met, the water is discharged or reused.

[0024] The intelligent electrical control cabinet 5, serving as the brain of the entire system, integrates a PLC controller, a 10-inch touchscreen human-machine interface, and various sensors (including online monitoring instruments for pH, temperature, pressure, liquid level, and flow). Through the programmed control, it enables one-button start / stop of the system, automatic adjustment of chemical dosage, automatic control of evaporator liquid level and temperature, linkage between ozone dosage and inlet water flow, fault alarms, and interlocking shutdown functions. This significantly reduces the workload of operators and ensures the stability and reliability of the system operation.

[0025] Example 2: Based on Example 1, this example is optimized for wastewater with higher salinity (TDS > 150 g / L) or a higher proportion of sodium sulfate. In the multi-effect evaporation salt precipitation unit, a third-effect falling film evaporator is added after the second-effect evaporator to further utilize the secondary steam from the second effect, reducing system steam consumption by approximately 25%. A DTB (Draft Tube Baffle) crystallizer is added after the cyclone flash crystallizer to obtain larger and purer salt crystals through internal circulation and fine crystal removal functions, improving the quality and value of the salt product. In the advanced oxidation unit, an ultraviolet photocatalytic oxidation device (UV / H2O2) is connected in series after the multiphase ozone catalytic oxidation reaction tower to further enhance the destruction of the most recalcitrant organic matter, ensuring that the effluent COD is consistently below the stringent emission standard of 50 mg / L.

[0026] Example 3: Building upon Example 1, this example provides a more compact, mobile design solution for the needs of small-scale pesticide production enterprises or intermittent wastewater treatment. The entire system (excluding the raw water storage tank and the clean water discharge pool) is integrated into a 40-foot standard shipping container. All pipes, pumps, and valves are pre-installed and commissioned at the factory, enabling rapid on-site connection and use. The multi-effect evaporation unit couples a single-effect evaporator with mechanical vapor recompression (MVR) technology. An electric compressor compresses and heats the secondary steam generated during evaporation, using it as the heat source for this effect. This significantly reduces dependence on external steam, requiring only electrical energy, making it more suitable for scenarios where steam access is inconvenient. The intelligent electrical control system integrates a wireless transmission module, enabling remote monitoring and fault diagnosis via a mobile app, greatly facilitating operation and maintenance management.

[0027] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0028] It should be noted that the components mentioned in the above embodiments are all general standard parts or components known to those skilled in the art. Their structures and principles can be learned by those skilled in the art through technical manuals or conventional experimental methods.

[0029] This utility model uses specific examples to illustrate its principles and implementation methods. The above description of the embodiments is only for the purpose of helping to understand the method and core idea of ​​this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the idea of ​​this utility model. In summary, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. A treatment system applied to high-salt high-COD pesticide wastewater, characterized in that, include: The pretreatment unit includes a raw water storage tank, a pH adjustment tank, a self-electrolysis coagulation and flocculation reaction tank, an inclined plate sedimentation tank, and a pretreated effluent tank connected in sequence. A multi-effect evaporation and salt precipitation unit includes a first-effect forced circulation evaporator and a second-effect forced circulation evaporator connected in series. The inlet of the first-effect forced circulation evaporator is connected to the outlet of the pre-treated water tank. The first-effect forced circulation evaporator is connected to a first-effect condensate tank. The second-effect forced circulation evaporator is connected to a second-effect condensate tank. Both the first-effect condensate tank and the second-effect condensate tank are connected to a mixed condensate tank. The second-effect forced circulation evaporator is connected to a cyclone flash crystallizer and a centrifuge. An advanced oxidation degradation unit includes a multiphase ozone catalytic oxidation reaction tower connected to the mixed condensate tank. The multiphase ozone catalytic oxidation reaction tower is equipped with a microporous titanium aeration disc connected to an ozone generator. The multiphase ozone catalytic oxidation reaction tower is also connected to an exhaust gas destroyer. The advanced treatment and discharge unit includes a neutralization sedimentation tank, which is connected to the multiphase ozone catalytic oxidation reaction tower and the multi-media filter. The multi-media filter is connected to the clear water discharge tank. The intelligent electrical control cabinet is electrically connected to each unit and is used for centralized control and monitoring.

2. The treatment system for high-salt, high-COD pesticide wastewater according to claim 1, characterized in that, The secondary steam outlet of the first-effect forced circulation evaporator is connected to the heating chamber inlet of the second-effect forced circulation evaporator, and the concentrated brine outlet of the second-effect forced circulation evaporator is connected to the inlet of the vortex flash crystallizer.

3. The treatment system for high-salt, high-COD pesticide wastewater according to claim 2, characterized in that, The bottom outlet of the cyclone flash crystallizer is connected to the centrifuge, the solid outlet of the centrifuge is connected to the packaging machine, and the liquid outlet is returned to the pretreatment outlet tank through a pipeline.

4. The treatment system for high-salt, high-COD pesticide wastewater according to claim 1, characterized in that, The multiphase ozone catalytic oxidation reaction tower is filled with multiphase aluminum-based ozone catalyst packing, and the bottom of the tower is equipped with the microporous titanium aeration disc, which is connected to the ozone generator.

5. The treatment system for high-salt, high-COD pesticide wastewater according to claim 1, characterized in that, The pretreatment unit is also equipped with a dosing device and a sludge thickening tank. The dosing device includes an acid tank, an alkali tank, a coagulant tank, and a flocculant tank, which are respectively connected to the pH adjustment tank and the self-electrolytic coagulation and flocculation reaction tank via metering pumps.

6. The treatment system for high-salt, high-COD pesticide wastewater according to claim 1, characterized in that, The multi-media filter includes a quartz sand layer and an activated carbon layer.

7. The treatment system for high-salt, high-COD pesticide wastewater according to claim 1, characterized in that, The intelligent electrical control cabinet integrates a PLC controller, touch screen, pH sensor, temperature sensor, pressure sensor and liquid level sensor to realize automatic control and remote monitoring.

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