High-salt organic wastewater resourceful treatment system and method

Abstract

The invention provides a resourceful treatment system and method for high-salinity organic wastewater, and the method comprises the following steps: high-salinity organic wastewater enters an adjusting tank to adjust the water quality and water quantity of the wastewater, then the wastewater is conveyed to an oxidation stripping tank, and the heated high-salinity organic wastewater is uniformly distributed on the upper-layer liquid level of the oxidation stripping tank through a wastewater inlet distribution pipe; an oxidizing agent and heating steam are uniformly distributed on the lower-layer liquid level of the oxidation stripping tank through a steam distribution pipe; the high-salinity wastewater from which organic matters are removed by the oxidation stripping tank is evaporated, cooled and depressurized by a flash tank and then enters an evaporative crystallization facility, and finally industrial salt meeting national and industrial standards is produced for commercial sales. According to the process, the removal rate of organic matters in the high-salt organic wastewater is 92.5%-95%, and the quality of industrial salt generated by an evaporative crystallization facility is ensured.

Description

Technical Field

[0001] The invention relates to a wastewater treatment technology, in particular to a resource recovery treatment process applied to high-salt organic wastewater. Background Art

[0002] High-salt organic wastewater refers to wastewater containing organic matter and at least 3.5% total dissolved solids (TDS). In addition to organic pollutants, these wastewaters also contain a large amount of inorganic salts. High-salt organic wastewater mainly comes from industrial production processes such as petrochemicals, food, and pharmaceuticals. Due to the characteristics of high organic matter and high salt content, this wastewater is difficult to treat.

[0003] Due to its high salt and high organic matter characteristics, if the salt in high-salt organic wastewater needs to be recycled, the organic matter in the wastewater must be removed first. The commonly used methods for removing organic matter in wastewater can be divided into advanced oxidation method, biochemical method, adsorption method, etc. Since the high salt content of high-salt organic wastewater inhibits the growth of microorganisms, the biochemical method cannot be used; due to the complex composition of high-salt organic wastewater, the adsorption method cannot guarantee the removal efficiency of organic matter in the effluent. At present, the main process for removing organic matter in high-salt organic wastewater is still advanced oxidation method.

[0004] Advanced oxidation technologies are mainly divided into several categories, including Fenton oxidation, electrocatalytic oxidation and wet oxidation. Since Fenton oxidation produces a large amount of iron-containing sludge during the treatment process, the salt in the high-salt organic wastewater cannot be recycled, so this process cannot be used to remove organic matter in high-salt organic wastewater; electrocatalytic oxidation is suitable for the removal of organic matter in high-salt organic wastewater, but its electrode materials are expensive, which greatly limits its use occasions; traditional wet oxidation requires high temperature and high pressure conditions, and its residence time is relatively long. Its equipment manufacturing has strict requirements on temperature and pressure resistance and corrosion resistance under high temperature and high pressure conditions. The equipment investment is large, which limits its scope of use.

[0005] With the increasing complexity of high-salinity and high-organic wastewater components and the increasing severity of the sewage treatment situation, a single treatment technology can no longer meet the high requirements of wastewater treatment, and the optimization and integration of multiple advanced treatment technologies has become the development trend of wastewater treatment. At the same time, the selection of wastewater treatment technology is based on two principles: one is the effective removal of salinity and organic matter, and the other is the cost of wastewater treatment technology. Summary of the invention

[0006] The present invention aims to provide a system and method for resource recovery of high-salt organic wastewater in response to the above-mentioned problems. The purpose of the present invention is to provide a wastewater treatment process that combines wet oxidation with steam stripping technology to remove organic matter from high-salt organic wastewater, thereby realizing resource recovery of salt in wastewater.

[0007] The purpose of the present invention can be achieved by the following solutions:

[0008] The invention discloses an oxidation stripping tank, which comprises an oxidation stripping tank body. The lower part and the upper part of the tank body are respectively provided with a steam distribution pipe and a wastewater inlet distribution pipe, and the steam distribution pipe is provided with an oxidant injection port.

[0009] In the oxidation stripping tank, a wastewater outlet is arranged at the bottom of the tank body, a stripping steam outlet is arranged at the top, and a demister and demister is arranged at the upper part.

[0010] In the oxidation stripping tank, an upper sieve plate is provided on the upper part of the wastewater inlet distribution pipe, a bottom supporting sieve plate is provided on the lower part of the steam distribution pipe, and a filler is provided between the upper sieve plate and the bottom supporting sieve plate.

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

[0012] The oxidant injection port is arranged at the center of the main pipe of the steam distribution pipe close to the outer side of the oxidation stripping tank pipe wall.

[0013] A system for resource treatment of high-salt organic wastewater using the above-mentioned oxidation stripping tank equipment, the system includes a regulating tank, the output end of the high-salt organic wastewater is connected to the regulating tank, the regulating tank is connected to a filter, a condensate heat exchanger, a steam heat exchanger and a wastewater inlet distribution pipe of the oxidation stripping tank in sequence; the oxidant and the heating steam are connected to the steam distribution pipe of the oxidation stripping tank; the wastewater output end of the oxidation stripping tank is connected to a flash tank and an evaporation crystallization facility in sequence.

[0014] In the above system, the steam of the oxidation stripping tank is connected to the steam heat exchanger through a temperature and pressure reducing device, 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 to the non-condensable heat exchanger, the exhaust gas washing tower and the wastewater biochemical treatment facility in sequence; the condensate output end of the steam heat exchanger is connected to the wastewater biochemical treatment facility through a condensate water heat exchanger.

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

[0016] A method for resource processing of high-salt organic wastewater using the above system, the method is to let the high-salt organic wastewater enter a regulating tank to adjust the water quality and water volume of the wastewater, and then transport 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, and the oxidant and heating steam are evenly distributed on the lower liquid surface of the oxidation stripping tank through a steam distribution pipe; the high-salt wastewater after organic matter is removed in the oxidation stripping tank is evaporated, cooled and depressurized in a flash tank, and then enters an evaporation crystallization facility to obtain the target product.

[0017] In the above method, the oxidant oxidizes and degrades the macromolecular organic matter in the high-salt organic wastewater into small molecular organic matter. Due to the low boiling point, the small molecular organic matter is stripped to the steam phase in the oxidation stripping tank. The stripping steam containing organic matter passes through a temperature and pressure reducer and then passes through a 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°C to 150°C, and the operating pressure is 0.1MPa to 0.5MPa.

[0019] In the above method, solid impurities in the wastewater are removed by filtering through a filter before being transported to the oxidation stripping tank, and the wastewater is then heated in turn through 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 the present invention: the function of the regulating tank is to store the high-salt organic wastewater generated by the front-end production devices, 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 water quality and quantity of the wastewater entering the back-end water treatment facility do not fluctuate greatly.

[0022] In the technical solution of the present invention: the lift of the pressurized feed pump needs to overcome the resistance drop of pipelines, pipe fittings and equipment and the pressure in the oxidation stripping tank, and a check valve should be provided at the outlet of the pressurized feed pump to prevent liquid reflux.

[0023] In the technical solution of the present invention: the filter needs to have a self-cleaning function, and the backwash water can be steam condensed water. The filter has a two-stage filter structure inside, and the coarse filter assembly filters out larger particles of impurities, and then reaches the fine filter, and the fine filter filters out fine particles of impurities.

[0024] In the technical solution of the present invention: the heat energy of the system is recovered and utilized through partition-type heat exchangers such as a condensate heat exchanger, a steam heat exchanger and a non-condensable gas heat exchanger.

[0025] In the technical solution of the present invention: the oxidation stripping tank is the core equipment for removing organic matter from high-salt organic wastewater. The heated high-salt organic wastewater is evenly distributed on the upper liquid surface of the oxidation stripping tank through the wastewater inlet distribution pipe, and the heated steam mixed with the oxidant is evenly distributed on the lower liquid surface of the oxidation stripping tank through the steam distribution pipe. The steam goes up along the gap on the surface of the packing to the upper liquid surface, and the high-salt organic wastewater runs along the gap on the surface of the packing to the bottom of the tank, and the two streams of fluid meet in the countercurrent gap on the surface of the packing. In the upper part of the packing layer, the high-concentration organic matter reacts with the low-concentration oxidant to achieve efficient utilization of the oxidant, and in the lower part of the packing layer, the low-concentration organic matter reacts with the high-concentration oxidant to achieve efficient removal of the organic matter. At the same time, the oxidant in the oxidation stripping tank oxidizes and degrades the macromolecular organic matter in the high-salt organic wastewater into small-molecule organic matter. Due to the low boiling point, the small-molecule organic matter is stripped to the steam phase in the oxidation stripping tank, thereby achieving more efficient removal of the organic matter in the high-salt organic wastewater.

[0026] Preferably, the effective volume of the regulating tank needs to meet the high-salt organic wastewater generation of each production unit for 12 to 24 hours, thereby ensuring the stability of the water quality and quantity delivered to the back-end wastewater treatment device.

[0027] Preferably, the pressurized feed pump should adopt 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 time.

[0028] As a preference, the filter needs to have a self-cleaning function, and the backwash water can be steam condensed water. The filter has a two-stage filter structure inside, where the coarse filter assembly filters out larger particles of impurities, and then reaches the fine filter, where fine particles of impurities are filtered out.

[0029] The beneficial effects of the invention are: the process has a removal rate of 92.5% to 95% for removing organic matter from high-salinity 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-salinity organic wastewater under conditions of lower temperature, pressure and less hydraulic retention time through wet oxidation and steam stripping synergistic technology, effectively reducing equipment investment and system operation stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a simplified process flow diagram of resource treatment of high-salt organic wastewater of the present invention:

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

[0032] Figure 2 This is a schematic diagram of the equipment of the core process equipment oxidation stripping tank of the present invention:

[0033] In the figure, 13-oxidation stripping tank body, 14-filler, 15-bottom supporting sieve plate, 16-upper sieve plate, 17-steam distribution pipe, 18-wastewater inlet distribution pipe, 19-demister and demister, 20-stripping steam outlet, 21-wastewater outlet, 22-oxidant injection port. DETAILED DESCRIPTION

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

[0035] like Figures 1-2 As shown, an oxidation stripping tank comprises an oxidation stripping tank body 13, the lower and upper parts of which 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 is provided with a wastewater outlet 21, the top is provided with a stripping steam outlet 20, and the upper part is also provided with a demister 19. The upper part of the wastewater inlet distribution pipe 18 is provided with an upper sieve plate 16, the lower part of the steam distribution pipe 17 is provided with a bottom support sieve plate 15, and a filler 14 is provided between the upper sieve plate 16 and the bottom support sieve plate 15. The filler 14 is fixed to the oxidation stripping tank barrel section through the bottom support sieve plate 15 and the upper sieve plate 16, and the steam distribution pipe 17 and the wastewater inlet distribution pipe 18 are buried in the filler layer; the oxidant injection port 22 is arranged at the center of the main pipe of the steam distribution pipe 17 close to the outer side of the oxidation stripping tank pipe wall.

[0036] A system for resource treatment of high-salt organic wastewater using the above-mentioned oxidation stripping tank equipment, the system comprises 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 the 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 sequentially connected to a flash tank 7 and an evaporation crystallization facility 8.

[0037] The steam of the oxidation stripping tank 6 is connected to the steam heat exchanger 5 through the temperature reducing and pressure reducing device 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 to the non-condensable heat exchanger 10, the exhaust gas washing tower 11 and the wastewater biochemical treatment facility 12 in sequence; the condensate output end of the steam heat exchanger 5 is connected to the wastewater biochemical treatment facility 12 through the condensate heat exchanger 4. A pressurized feed pump 2 is also provided between the regulating tank 1 and the filter 3.

[0038] Embodiment 1,

[0039] A petrochemical enterprise has high-salt wastewater containing aniline, with a water volume of 4t t / h to 8t / h and a salt content of 10% to 12.5%. The high-salt organic wastewater enters the regulating tank 1 to adjust the water quality and water volume of the wastewater, so that the wastewater volume is stabilized at 6t / h, the organic matter COD content in the wastewater is 2000mg / L to 3000mg / L, and the pH value is 6 to 7. The wastewater is transported to the oxidation stripping tank 6 by the pressurized feed pump 2. In this process, the solid impurities in the wastewater must be filtered through the filter 3 to remove the solid impurities, and then the condensed water heat exchanger 4 and the steam heat exchanger 5 are used to heat the wastewater; the high-salt organic wastewater heated to 80°C to 125°C is evenly distributed on the upper liquid surface of the oxidation stripping tank 6 through the wastewater inlet distribution pipe 18, and the oxidant and the heating steam are evenly distributed on the lower liquid surface of the oxidation stripping tank 6 through the steam distribution pipe 17. The oxidant hydrogen peroxide oxidizes and degrades the macromolecular organic matter in the high-salt organic wastewater into small molecular organic matter. Due to the low boiling point, the small molecular organic matter is stripped to the steam phase in the oxidation stripping tank, and the stripping steam containing organic matter passes through the temperature and pressure reducer 9. Then, together with the low-pressure saturated steam discharged from the flash tank 7, it is cooled through the steam heat exchanger 5, the non-condenser heat exchanger 10 and the condensate heat exchanger 4 for heat exchange. After cooling, the condensate is discharged to the wastewater biochemical treatment facility 12, and the non-condensable gas is treated by the waste gas washing tower 11 and then discharged. The waste gas washing tower 11 discharges the liquid to the wastewater biochemical treatment facility 12. After the organic matter is removed by the oxidation stripping tank 6, the COD content of organic matter in the high-salt wastewater is reduced to 150 mg / L to 200 mg / L. The salt-containing wastewater is evaporated, cooled and depressurized by the flash tank 7 and then enters the evaporation crystallization facility, and finally industrial salt that meets the national and industry standards "Industrial Salt GB / T5462-2015" is produced for commercial sales.

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

[0041] Preferably, the filler 14 in the oxidation stripping tank 6 is a porous medium having the ability to adsorb organic matter, and may be a zeolite or activated carbon or a similar substance or a mixture thereof, and the filler is preferably used as a carrier material for catalytically oxidizing active substances, thereby further enhancing the oxidizing performance of the oxidant and ensuring the oxidative degradation rate of organic matter.

[0042] Embodiment 2:

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

Claims

1. An oxidation stripping tank, characterized in that: The device comprises an oxidation stripping tank body (13), the lower part and the upper part of which 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).

2. The oxidation stripping tank according to claim 1, characterized in that: The bottom of the tank body is provided with a wastewater outlet (21), the top is provided with a stripping steam outlet (20), and the upper part is also provided with a demister (19).

3. The oxidation stripping tank according to claim 1, characterized in that: An upper sieve plate (16) is provided at the upper part of the wastewater inlet distribution pipe (18), a bottom supporting sieve plate (15) is provided at the lower part of the steam distribution pipe (17), and a filler (14) is provided between the upper sieve plate (16) and the bottom supporting sieve plate (15). Preferably: the filler (14) is fixed to the barrel section of the oxidation stripping tank through a bottom support sieve plate (15) and an upper sieve plate (16), and the steam distribution pipe (17) and the wastewater inlet distribution pipe (18) are buried in the filler layer; The oxidant injection port (22) is arranged at the center of the main pipe of the steam distribution pipe (17) close to the outer side of the oxidation stripping tank pipe wall.

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

5. The system according to claim 4, characterized in that The steam of the oxidation stripping tank (6) is connected to the steam heat exchanger (5) through a temperature reducing and pressure reducing device (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 to the non-condensable gas heat exchanger (10), the waste gas washing tower (11) and the wastewater biochemical treatment facility (12) in sequence; the condensate output end of the steam heat exchanger (5) is connected to the wastewater biochemical treatment facility (12) through a condensate water heat exchanger (4).

6. 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).

7. A method for resource treatment of high-salt organic wastewater using the system of claim 4, characterized in that: The method comprises the following steps: high-salt organic wastewater is introduced into a regulating tank (1) to regulate the water quality and water volume of the wastewater, and then the wastewater is transported 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), and the oxidant and the heating steam are evenly distributed on the lower liquid surface of the oxidation stripping tank (6); the high-salt wastewater after organic matter is removed in the oxidation stripping tank (6) is evaporated, cooled and depressurized in a flash tank (7), and then enters an evaporation crystallization facility (8) to obtain a target product.

8. The method according to claim 7, characterized in that The oxidant oxidizes and degrades the macromolecular organic matter in the high-salt organic wastewater into small molecular organic matter. The small molecular organic matter is stripped to the steam phase in the oxidation stripping tank due to its low boiling point. The stripping steam containing organic matter passes through a temperature reducing and pressure reducing device (9) and then passes through a steam heat exchanger (5) together with the low-pressure saturated steam discharged from a flash tank (7).

9. The method according to claim 7, characterized in that: The operating temperature of the oxidation stripping tank is 100℃~150℃, and the operating pressure is 0.1MPa to 0.5MPa.

10. The method according to claim 7, characterized in that Before being transported to the oxidation stripping tank (6), the solid impurities in the wastewater are removed by filtering through a filter (3), and then the wastewater is heated in turn through a condensate heat exchanger (4) and a steam heat exchanger (5).

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