A high-salt organic wastewater resourceful treatment system and method

Abstract

The application provides a high-salt organic wastewater resource treatment system and method. The method is that high-salt organic wastewater is sent into a regulating tank to regulate the water quality and water volume of the wastewater, and then is sent to an oxidation stripping tank. The heated high-salt organic wastewater is uniformly distributed on the upper liquid surface of the oxidation stripping tank through a wastewater inlet distribution pipe, and an oxidizing agent and heated steam are uniformly distributed on the lower liquid surface of the oxidation stripping tank through a steam distribution pipe. The high-salt wastewater after the removal of organic matters in the oxidation stripping tank is sent into an evaporation crystallization facility through a flash tank after evaporation, cooling and pressure reduction, and finally industrial salt meeting the national and industrial standards is produced for commercial sale. The removal rate of organic matters in the high-salt organic wastewater is 92.5% to 95% in the process, and the quality of the industrial salt produced by the evaporation crystallization facility is ensured.

Description

Technical Field

[0001] This invention relates to a wastewater treatment technology, specifically a resource-based treatment process for high-salt organic wastewater. Background Technology

[0002] High-salinity organic wastewater refers to wastewater containing organic matter and at least 3.5% total dissolved solids (TDS). In addition to organic pollutants, this wastewater also contains large amounts of inorganic salts. High-salinity organic wastewater mainly originates from industrial production processes in petrochemicals, food processing, and pharmaceuticals. Due to its high organic matter and high salinity, this type of wastewater is difficult to treat.

[0003] Due to its high salt and organic matter content, high-salt organic wastewater requires the removal of organic matter before it can be recycled. Common methods for removing organic matter from wastewater include advanced oxidation, biochemical methods, and adsorption. However, because the high salt content of high-salt organic wastewater inhibits microbial growth, biochemical methods are not feasible. Furthermore, due to the complex composition of high-salt organic wastewater, adsorption methods cannot guarantee efficient removal of organic matter from the effluent. Currently, advanced oxidation is the primary process used for removing organic matter from high-salt organic wastewater.

[0004] Advanced oxidation technologies are mainly classified into several categories, including Fenton oxidation, electrocatalytic oxidation, and wet oxidation. Fenton oxidation generates a large amount of iron-containing sludge during the process, making it impossible to recover the salt content in high-salt organic wastewater. Therefore, this process cannot be applied to the removal of organic matter from high-salt organic wastewater. Electrocatalytic oxidation is suitable for removing organic matter from high-salt organic wastewater, but the high cost of its electrode materials greatly limits its application. Traditional wet oxidation requires high-temperature and high-pressure conditions and a long residence time. Its equipment manufacturing has stringent requirements for temperature and pressure resistance, as well as corrosion resistance under high-temperature and high-pressure conditions, resulting in large equipment investments and limiting its application scope.

[0005] With the increasing complexity of high-salinity and high-organic-content wastewater composition and the growing severity of wastewater treatment challenges, single treatment technologies are no longer sufficient to meet the high requirements of wastewater treatment. The optimized integration of multiple advanced treatment technologies has become a development trend in wastewater treatment. Meanwhile, the selection of wastewater treatment technologies is based on two principles: effective removal of salinity and organic matter, and consideration of the cost of the wastewater treatment technology. Summary of the Invention

[0006] This invention addresses the aforementioned problems by providing a system and method for the resource-based treatment of high-salt organic wastewater. The objective of this invention is to provide a wastewater treatment process that combines wet oxidation and stripping technology to remove organic matter from high-salt organic wastewater, thereby achieving the resource-based recovery of salt from the wastewater.

[0007] The objective of this invention can be achieved through the following methods:

[0008] An oxidative stripping tank is provided. The equipment includes an oxidative stripping tank body, with a steam distribution pipe at the lower part and a wastewater inlet distribution pipe at the upper part of the tank body, and an oxidant injection port on the steam distribution pipe.

[0009] The oxidation stripping tank is provided with a wastewater outlet at the bottom, a stripping steam outlet at the top, and a demister at the top.

[0010] In the aforementioned oxidation stripping tank, an upper screen plate is provided at the top of the wastewater inlet distribution pipe, and a bottom support screen plate is provided at the bottom of the steam distribution pipe. Packing material is provided between the upper screen plate and the bottom support screen plate.

[0011] Preferably, the packing is fixed to the cylinder section of the oxidation stripping tank by the bottom support screen plate and the upper screen plate, and the steam distribution pipe and the wastewater inlet distribution pipe are buried in the packing layer;

[0012] The oxidant injection port is located near the outside of the oxidizing stripping tank pipe wall, at the center of the main steam distribution pipe.

[0013] A system for the resource-based treatment of high-salt organic wastewater using the aforementioned oxidative stripping tank equipment. The system includes a regulating tank, the output end of which is connected to the regulating tank. The regulating tank is sequentially connected to a filter, a condensate heat exchanger, a steam heat exchanger, and the wastewater inlet distribution pipe of the oxidative stripping tank. The oxidant and heating steam are connected to the steam distribution pipe of the oxidative stripping tank. The wastewater output end of the oxidative stripping tank is sequentially connected to a flash tank and an evaporation crystallization facility.

[0014] In the above system, the steam from the oxidation stripping tank is connected to the steam heat exchanger via a desuperheater and pressure reducer, and the steam output end of the flash tank is also connected to the steam heat exchanger. The non-condensable gas output end of the steam heat exchanger is connected in sequence to the non-condensable heat exchanger, the waste gas scrubbing tower, and the wastewater biochemical treatment facility; the condensate output end of the steam heat exchanger is connected to the wastewater biochemical treatment facility via a condensate heat exchanger.

[0015] In the above system, a pressurized feed pump is also installed between the regulating tank and the filter.

[0016] A method for resource-based treatment of high-salt organic wastewater using the above-mentioned system is provided. The method involves adjusting the water quality and quantity of the high-salt organic wastewater in a regulating tank, then conveying it to an oxidation stripping tank. The heated high-salt organic wastewater is evenly distributed on the upper liquid surface of the oxidation stripping tank through a wastewater inlet distribution pipe, while the oxidant and heating steam are evenly distributed on the lower liquid surface of the oxidation stripping tank through a steam distribution pipe. After the high-salt wastewater has had its organic matter removed in the oxidation stripping tank, it is evaporated, cooled, and depressurized in a flash tank before entering an evaporation crystallization facility to obtain the target product.

[0017] In the above method, the oxidant oxidizes and degrades the large molecular organic matter in the high-salt organic wastewater into small molecular organic matter. Since the small molecular organic matter has a lower boiling point, it is stripped into the steam phase in the oxidative stripping tank. The stripping steam containing organic matter passes through the desuperheater and pressure reducer and then passes through the steam heat exchanger together with the low-pressure saturated steam discharged from the flash tank.

[0018] In the above method, the operating temperature of the oxidation stripping tank is 100℃~150℃ and the operating pressure is 0.1MPa to 0.5MPa.

[0019] In the above method, the wastewater is filtered to remove solid impurities before being transported to the oxidation stripping tank, and then heated sequentially by a condensate heat exchanger and a steam heat exchanger.

[0020] In some more specific technical solutions, the technical solutions of the present invention are as follows:

[0021] In the technical solution of this invention: the function of the regulating tank is to store the high-salt organic wastewater generated by each production device at the front end, mix and homogenize it, and adjust the pH value of the high-salt organic wastewater by adding acid and alkali, so as to ensure that the quality and quantity of wastewater entering the downstream water treatment facility do not fluctuate significantly.

[0022] In the technical solution of this invention: the head of the pressurized feed pump needs to overcome the resistance drop of the pipeline, fittings and equipment and the pressure inside the oxidation stripping tank. A check valve should be installed at the outlet of the pressurized feed pump to prevent liquid backflow.

[0023] In this invention, the filter must have a self-cleaning function, and the backwash water can be steam condensate. The filter has a two-stage filter structure: the coarse filter removes larger particles of impurities, and then the filter reaches the fine filter, which removes smaller particles of impurities.

[0024] In the technical solution of this invention, the heat energy of the system is recovered and utilized through indirect heat exchangers such as condensate heat exchangers, steam heat exchangers, and non-condensable gas heat exchangers.

[0025] In this invention, the oxidative stripping tank is the core equipment for removing organic matter from high-salt organic wastewater. Heated high-salt organic wastewater is evenly distributed on the upper liquid surface of the oxidative stripping tank through a wastewater inlet distribution pipe. Heating steam mixed with oxidant is evenly distributed on the lower liquid surface of the oxidative stripping tank through a steam distribution pipe. The steam rises to the upper liquid surface along the gaps on the packing surface, while the high-salt organic wastewater flows towards the bottom of the tank along the gaps on the packing surface. The two fluids meet counter-currently at the gaps on the packing surface. In the upper part of the packing layer, high-concentration organic matter reacts with low-concentration oxidant, achieving efficient utilization of the oxidant. In the lower part of the packing layer, low-concentration organic matter reacts with high-concentration oxidant, achieving efficient removal of organic matter. Simultaneously, the oxidant in the oxidative stripping tank oxidizes and degrades large-molecule organic matter in the high-salt organic wastewater into small-molecule organic matter. Because of their lower boiling points, these small-molecule organic matter is stripped into the vapor phase in the oxidative stripping tank, achieving even more efficient removal of organic matter from the high-salt organic wastewater.

[0026] Preferably, the effective volume of the regulating tank should meet the high-salt organic wastewater production of each production unit for 12 to 24 hours, thereby ensuring the stability of the water quality and quantity transported to the downstream wastewater treatment unit.

[0027] As a preferred option, the pressurized feed pump should be a variable frequency pump, so as to reduce the flow rate of wastewater entering the treatment device when the organic matter content in the high-salt organic wastewater exceeds the design limit for a short period of time.

[0028] Preferably, the filter should have a self-cleaning function, and the backwash water can be steam condensate. The filter has a two-stage filter structure. The coarse filter removes larger particles of impurities, and then the particles pass to the fine filter to remove finer particles.

[0029] The beneficial effects of the invention are as follows: the process removes 92.5% to 95% of organic matter from high-salt organic wastewater, ensuring the quality of industrial salt produced by the evaporation and crystallization facility. Compared with traditional wet oxidation technology, this process can achieve efficient removal of organic matter from high-salt organic wastewater under conditions of lower temperature and pressure and shorter hydraulic residence time through wet oxidation and stripping synergistic technology, effectively reducing equipment investment and system operation stability. Attached Figure Description

[0030] Figure 1 Here is a simplified flow chart of a resource-based treatment process for high-salt organic wastewater according to the present invention:

[0031] In the diagram, 1—regulating tank, 2—pressurized feed pump, 3—filter, 4—condensate heat exchanger, 5—steam heat exchanger, 6—oxidation stripping tank, 7—flash tank, 8—steam crystallization facility, 9—desuperheater and pressure reducer, 10—non-condensable heat exchanger, 11—waste gas scrubbing tower, 12—wastewater biochemical treatment facility.

[0032] Figure 2 Here is a simplified diagram of the core process equipment of this invention: the oxidation stripping tank.

[0033] In the figure, 13-Oxidation stripping tank body, 14-Packing, 15-Bottom support screen plate, 16-Upper screen plate, 17-Steam distribution pipe, 18-Wastewater inlet distribution pipe, 19-Demisting and demister, 20-Stripping steam outlet, 21-Wastewater discharge outlet, 22-Oxidant injection port. Detailed Implementation

[0034] To better understand the above technical solution, the present invention will be described in detail below with specific implementation methods, but the scope of protection of the present invention is not limited thereto:

[0035] like Figures 1-2 As shown, an oxidative stripping tank includes a tank body 13. The lower and upper parts of the tank body are respectively provided with a steam distribution pipe 17 and a wastewater inlet distribution pipe 18, and the steam distribution pipe 17 is provided with an oxidant injection port 22. The bottom of the tank body has a wastewater discharge port 21, the top has a stripping steam outlet 20, and a demister 19 is also provided at the top. The upper part of the wastewater inlet distribution pipe 18 is provided with an upper screen plate 16, and the lower part of the steam distribution pipe 17 is provided with a bottom support screen plate 15. Packing material 14 is provided between the upper screen plate 16 and the bottom support screen plate 15. The packing material 14 is fixed to the oxidative stripping tank body section by the bottom support screen plate 15 and the upper screen plate 16. The steam distribution pipe 17 and the wastewater inlet distribution pipe 18 are embedded in the packing layer. The oxidant injection port 22 is located near the outer side of the oxidative stripping tank pipe wall at the center of the main steam distribution pipe 17.

[0036] A system for the resource-based treatment of high-salt organic wastewater using the aforementioned oxidation stripping tank equipment includes a regulating tank 1. The output end of the high-salt organic wastewater is connected to the regulating tank 1. The regulating tank 1 is sequentially connected to a filter 3, a condensate heat exchanger 4, a steam heat exchanger 5, and a wastewater inlet distribution pipe 18 of the oxidation stripping tank. The oxidant and heating steam are connected to a steam distribution pipe 17 of the oxidation stripping tank 6. The wastewater output end of the oxidation stripping tank is sequentially connected to a flash tank 7 and an evaporation crystallization facility 8.

[0037] Steam from the oxidation stripping tank 6 is connected to the steam heat exchanger 5 via a desuperheater and pressure reducer 9. The steam output of the flash tank 7 is also connected to the steam heat exchanger 5. The non-condensable gas output of the steam heat exchanger 5 is sequentially connected to the non-condensable heat exchanger 10, the waste gas scrubbing tower 11, and the wastewater biological treatment facility 12. The condensate output of the steam heat exchanger 5 is connected to the wastewater biological treatment facility 12 via a condensate heat exchanger 4. A pressurized feed pump 2 is also installed between the regulating tank 1 and the filter 3.

[0038] Example 1,

[0039] A petrochemical enterprise has a high-salt wastewater containing aniline, with a flow rate of 4 to 8 t / h. The high-salt organic wastewater with a salt content of 10% to 12.5% ​​enters the equalization tank 1 to adjust the wastewater quality and flow rate, so that the wastewater flow rate is stabilized at 6 t / h. The organic matter COD content in the wastewater is 2000 mg / L to 3000 mg / L, and the pH value is 6 to 7. The wastewater is fed to the oxidation stripping tank 6 via a pressurized feed pump 2. During this process, the wastewater is first filtered by a filter 3 to remove solid impurities, and then heated by a condensate heat exchanger 4 and a steam heat exchanger 5. The high-salt organic wastewater, heated to 80℃~125℃, is evenly distributed on the upper liquid surface of the oxidation stripping tank 6 through a wastewater inlet distribution pipe 18. The oxidant and heating steam are evenly distributed on the lower liquid surface of the oxidation stripping tank 6 through a steam distribution pipe 17. The hydrogen peroxide oxidizes and degrades the large-molecule organic matter in the high-salt organic wastewater into smaller-molecule organic matter. Because of their lower boiling points, these smaller-molecule organic matter is stripped into the vapor phase in the oxidation stripping tank. The stripping steam containing organic matter passes through a desuperheater and pressure reducer 9. The low-pressure saturated steam discharged from flash tank 7 is then cooled by heat exchange through steam heat exchanger 5, non-condensable heat exchanger 10, and condensate heat exchanger 4. After cooling, the condensate is discharged to wastewater biochemical treatment facility 12. The non-condensable gas is treated by waste gas scrubbing tower 11 and then discharged. The waste gas scrubbing tower 11 discharges liquid to wastewater biochemical treatment facility 12. After organic matter is removed by oxidative stripping tank 6, the organic matter COD content in the high-salt wastewater is reduced to 150mg / L to 200mg / L. The saline wastewater is then cooled and depressurized by evaporation in flash tank 7 and then enters the evaporation crystallization facility. Finally, industrial salt that meets the national and industry standard "Industrial Salt GB / T5462-2015" is produced and sold commercially.

[0040] The operating temperature of the oxidation stripping tank 6 should be 100℃~150℃, and the operating pressure should be 0.1MPa to 0.5MPa. The hydraulic retention time of high-salt organic wastewater in the oxidation stripping tank should be 30 to 40 minutes.

[0041] Preferably, the packing material 14 in the oxidative stripping tank 6 is a porous medium with the ability to adsorb organic matter. It can be zeolite or activated carbon or similar substances or mixtures thereof. The packing material is preferably used as a carrier material for catalytic oxidation active substances, thereby further enhancing the oxidation performance of the oxidant and ensuring the oxidation degradation rate of organic matter.

[0042] Example 2:

[0043] The high-salt wastewater was treated in the same way as in Example 1. The organic matter in the high-salt wastewater was removed using a traditional high-temperature wet oxidation process. The high-temperature wet oxidation tower operated at a temperature of 250°C and a pressure of 2.5 MPa. The hydraulic retention time of the wastewater was 45 min. After treatment by the high-temperature wet oxidation tower, the COD content of organic matter in the high-salt wastewater was reduced to 200 mg / L to 300 mg / L.

Claims

1. An oxidation stripping tank, characterized in that, It includes an oxidative stripping tank body (13), the lower part and the upper part of the tank body are respectively provided with a steam distribution pipe (17) and a wastewater inlet distribution pipe (18), and the steam distribution pipe (17) is provided with an oxidant injection port (22); The upper part of the wastewater inlet distribution pipe (18) is provided with an upper screen plate (16), and the lower part of the steam distribution pipe (17) is provided with a bottom support screen plate (15). A packing material (14) is provided between the upper screen plate (16) and the bottom support screen plate (15). The packing material (14) is fixed to the cylinder section of the oxidation stripping tank by the bottom support screen plate (15) and the upper screen plate (16). The steam distribution pipe (17) and the wastewater inlet distribution pipe (18) are buried in the packing layer. The oxidant injection port (22) is located near the outside of the tube wall of the oxidation stripping tank at the center of the main tube of the steam distribution pipe (17).

2. The oxidation stripping tank according to claim 1, characterized in that, The tank has a wastewater outlet (21) at the bottom, a steam stripping outlet (20) at the top, and a demister (19) at the top.

3. A system for the resource-based treatment of high-salt organic wastewater using the oxidative stripping tank described in claim 1, characterized in that, The system includes a regulating tank (1), the output end of the high-salt organic wastewater is connected to the regulating tank (1), the regulating tank (1) is connected in sequence to a filter (3), a condensate heat exchanger (4), a steam heat exchanger (5) and the wastewater inlet distribution pipe (18) of the oxidation stripping tank; the oxidant and heating steam are connected to the steam distribution pipe (17) of the oxidation stripping tank (6); the wastewater output end of the oxidation stripping tank is connected in sequence to a flash tank (7) and an evaporation crystallization facility (8).

4. The system according to claim 3, characterized in that, The steam from the oxidative stripping tank (6) is connected to the steam heat exchanger (5) via the desuperheater and pressure reducer (9). The steam output end of the flash tank (7) is also connected to the steam heat exchanger (5). The non-condensable gas output end of the steam heat exchanger (5) is connected in sequence to the non-condensable heat exchanger (10), the waste gas scrubbing tower (11), and the wastewater biochemical treatment facility (12). The condensate output end of the steam heat exchanger (5) is connected to the wastewater biochemical treatment facility (12) via the condensate heat exchanger (4).

5. The system according to claim 4, characterized in that, A pressurized feed pump (2) is also provided between the regulating tank (1) and the filter (3).

6. A method for resource-based treatment of high-salt organic wastewater using the system described in claim 3, characterized in that, The method involves feeding high-salt organic wastewater into a regulating tank (1) to adjust the water quality and quantity, and then transporting it to an oxidation stripping tank (6). The heated high-salt organic wastewater is evenly distributed on the upper liquid surface of the oxidation stripping tank (6), while the oxidant and heating steam are evenly distributed on the lower liquid surface of the oxidation stripping tank (6). After the high-salt wastewater has been decomposed by the oxidation stripping tank (6), it is evaporated, cooled, and depressurized in a flash tank (7) before entering an evaporation crystallization facility (8) to obtain the target product. The operating temperature of the oxidation stripping tank is 100℃~150℃, and the operating pressure is 0.1MPa to 0.5MPa.

7. The method according to claim 6, characterized in that, The oxidant oxidizes and degrades the large molecular organic matter in the high-salt organic wastewater into small molecular organic matter. Since the small molecular organic matter has a lower boiling point, it is stripped into the steam phase in the oxidative stripping tank. The stripping steam containing organic matter passes through the desuperheating and pressure reducing device (9) and then passes through the steam heat exchanger (5) together with the low-pressure saturated steam discharged from the flash tank (7).

8. The method according to claim 6, characterized in that, Before being transported to the oxidation stripping tank (6), the wastewater is filtered by a filter (3) to remove solid impurities, and then heated sequentially by a condensate heat exchanger (4) and a steam heat exchanger (5).

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