Preserved szechuan pickle wastewater treatment and resource recycling method

Abstract

The invention discloses a preserved szechuan pickle wastewater treatment and resource recycling method, and belongs to the technical field of wastewater treatment. The method disclosed by the invention comprises the following steps: intercepting suspended pollutants from the preserved szechuan pickle wastewater and the comprehensive preserved szechuan pickle wastewater through a grating, and then mixing; then treating through a high-temperature wet oxidation system, then adjusting the pH value to 3-6, then carrying out three-dimensional electrolysis, then treating through a second coagulating sedimentation system, then adding a denitrification microbial strain for treatment, carrying out deep treatment through an ozone catalytic oxidation system, and then filtering through a material membrane. The removal rate of organic matters in the preserved szechuan pickle wastewater treated by the method is up to 99.9%, and the COD of the effluent is less than or equal to 100mg / L; the total nitrogen removal rate is up to 98-99%, and the total nitrogen in the effluent is less than or equal to 70mg / L; the removal rate of total phosphorus is up to 98.7-99.9%, the total phosphorus in the effluent is less than or equal to 0.5 mg / L, the chloride in the effluent is less than 5000 mg / L, and meanwhile, the salt in the wastewater is recycled to generate a product.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and particularly relates to a method for treating mustard tuber wastewater and recycling resources. Background Art

[0002] According to the "Water Pollutant Discharge Standard for the Preservative Industry" (DB50 / 1050-2020), the chloride content in mustard wastewater should be controlled within 8,000 mg / L. By 2025, the chloride content is required to be controlled within 5,000 mg / L. Recycling the high-salt content in mustard wastewater is crucial for companies.

[0003] Wastewater generated by the production of mustard tubers is characterized by high levels of salt, COD, nitrogen, and phosphorus. This includes wastewater from primary processing, the first, second, and third pickling stages. Comprehensive wastewater includes wastewater from washing, cutting, desalting, dehydrating, mixing, sterilizing, and flushing equipment.

[0004] Both wastewater streams contain high levels of organic matter and salt concentrations, making them suitable for recycling. Conventional wastewater treatment uses advanced oxidation technology for pretreatment to remove total phosphorus, followed by biochemical treatment. However, due to the high salinity in the wastewater, microorganisms adapted to higher salt concentrations are required to decompose the organic matter, resulting in low treatment efficiency. This treatment method also fails to realize wastewater resource utilization and control chloride emissions. Furthermore, the treatment facilities require large investment and land occupation, resulting in high operating costs. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for treating mustard wastewater and recycling resources. The present invention can effectively and stably remove organic matter in mustard wastewater through "wet oxidation + three-dimensional electrolysis + special denitrification bacteria + ozone + material membrane" technology, with a removal rate of up to 99.9%, and effluent COD ≤ 100 mg / L; the total nitrogen removal rate is as high as 98-99%, and the effluent total nitrogen ≤ 70 mg / L; the total phosphorus removal rate is as high as 98.7-99.9%, and the effluent total phosphorus ≤ 0.5 mg / L.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for treating mustard tuber wastewater and recycling resources, comprising the following steps:

[0008] S1. The mustard wastewater and the mustard comprehensive wastewater are mixed after passing through a screen to intercept suspended pollutants to obtain the wastewater to be treated;

[0009] S2. The wastewater to be treated is treated by a high-temperature wet oxidation system to obtain a first treated wastewater;

[0010] S3. The low organic matter concentration wastewater is treated by a first coagulation and sedimentation system to obtain a second treated wastewater and a first precipitated sludge;

[0011] S4. The second treated wastewater is adjusted to a pH of 3 to 6 and then subjected to three-dimensional electrolysis to obtain a third treated wastewater;

[0012] S5. The third treated wastewater is treated by a second coagulation and sedimentation system to obtain a fourth treated wastewater and a second precipitated sludge;

[0013] S6. Adding denitrifying microorganisms to the fourth treated wastewater to obtain a fifth treated wastewater;

[0014] S7. The fifth treated wastewater is subjected to an ozone catalytic oxidation system for deep treatment and then filtered through a material membrane to obtain the sixth treated wastewater.

[0015] As a preference, the S1 mustard tuber wastewater (pickled wastewater) contains COD Cr 30000~40000mg / L, total nitrogen concentration 1500~2500mg / L, total phosphorus 150~200mg / L, salinity 10~15%, chloride ion 60~100g / L; mustard integrated wastewater: COD Cr 3000~4000mg / L, total nitrogen concentration 200~300mg / L, total phosphorus 25~40mg / L, salinity 2~3%, chloride ion 7~13g / L.

[0016] Preferably, the volume ratio of the mustard tuber wastewater to the mustard tuber comprehensive wastewater in S1 is (3-4):100.

[0017] Preferably, the treatment method of the high temperature wet oxidation system in S2 is: under high temperature and high pressure, the organic matter in the wastewater is oxidized into carbon dioxide and water using oxygen in the air as an oxidant; the temperature is controlled at 450-600°C, and the pressure is controlled at 20-200atm.

[0018] By adopting the above technical solution, the present invention allows the organic matter in the wastewater to undergo oxidative decomposition reaction under the conditions of high temperature and high pressure in the high-temperature wet oxidation system, and complex organic pollutants such as benzene series and nitrides are completely oxidized, the concentration of organic matter is gradually reduced, and ultimately the pollutants are degraded.

[0019] Preferably, the treatment method of the first coagulation and sedimentation system in S3 is: adjusting the pH of the wastewater to 7.5-9.5 and adding coagulant PAC at the same time.

[0020] The present invention can remove suspended matter and phosphorus-containing compounds in wastewater by adopting the above technical solution, and gradually aggregate the suspended matter and pollutants in the water to form large suspended matter through the bridging effect, electrical neutralization effect and netting effect of the coagulant PAC; under the hydraulic flow, the flocculant PAM is then added to adsorb the suspended particles in the water, play a linking and bridging role between the particles, so that the fine particles form relatively large flocs, and the precipitation speed of the particles is accelerated.

[0021] As a preference, the three-dimensional electrolysis parameters in S4 are as follows: pH 4-6, plate spacing 5-30 cm, current density 10-50 mA / cm 2 , effective stay time is 1 to 2 hours.

[0022] The present invention utilizes the high potential of the electrochemical anode of three-dimensional electrolysis to directly oxidize and destroy macromolecular organic matter in the wastewater, thereby removing part of COD and ammonia nitrogen in the wastewater.

[0023] Preferably, the treatment method of the second coagulation sedimentation system in S5 is: adjusting the wastewater pH to maintain at 7.5-9.5, then neutralizing and aerating for 0.5-1 hour; and simultaneously adding coagulant PAC and flocculant PAM.

[0024] The present invention simultaneously adds coagulant PAC and flocculant PAM, and finally the pollutants are precipitated and removed in the form of sludge in the sedimentation zone.

[0025] Preferably, the denitrifying microorganisms in S6 are autotrophic short-range nitrifying and denitrifying microorganisms, and salt-tolerant special denitrifying bacteria.

[0026] The present invention adds high-efficiency special denitrifying microbial strains to directly degrade ammonia nitrogen into nitrogen (N2) without consuming the carbon source (BOD). It not only removes ammonia nitrogen, but also reduces the total nitrogen index, which is beneficial to the efficiency of the subsequent treatment.

[0027] Preferably, the ozone catalytic oxidation system treatment method in S7 is: utilizing the strong oxidizing property of O3 and the efficient catalytic activity of the catalyst, the organic matter undergoes oxidation reaction on the catalyst surface, and the ozone dosage is 100-500 mg / L.

[0028] The present invention utilizes the strong oxidizing property of O3 and the efficient catalytic activity of the catalyst to further oxidatively decompose the residual difficult-to-degrade organic matter in the wastewater, and decolorizes it at the same time, ensuring that the final effluent meets the feed requirements of the material membrane, and can also generally improve the purity of the ion membrane feed liquid product.

[0029] Preferably, the membrane used for membrane filtration in S7 is a material membrane that only allows water molecules to pass through and retains salts.

[0030] The present invention utilizes the characteristics of the material membrane to intercept pollutants but not to intercept salts. Part of the wastewater that intercepts pollutants can meet the discharge requirements, and the wastewater containing salt can be collected and reused.

[0031] Preferably, the sludge is bagged after dehydration and outsourced for regular processing.

[0032] Contains at least the following beneficial technical effects:

[0033] The present invention can effectively and stably remove organic matter in mustard wastewater through the "wet oxidation + three-dimensional electrolysis + special denitrifying bacteria + ozone + material membrane" technology, with a removal rate of up to 99.9%, and effluent COD ≤ 100 mg / L; the total nitrogen removal rate is as high as 98-99%, and the effluent total nitrogen ≤ 70 mg / L; the total phosphorus removal rate is as high as 98.7-99.9%, and the effluent total phosphorus ≤ 0.5 mg / L.

[0034] The present invention can efficiently recover salt in wastewater and turn it into an ion membrane feed liquid product, thereby realizing salt resource recovery and reuse.

[0035] The present invention treats the mustard tuber wastewater to meet the standards, so that the effluent meets the requirements of the "Water Pollutant Discharge Standard for the Mustard Tuber Industry" (DB50 / 1050-2020), and meets the discharge standards, especially chloride <5000 mg / L. It is highly targeted at the wastewater projects in the mustard tuber industry and has good environmental benefits and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a wastewater treatment flow chart of Example 1 of the present invention. DETAILED DESCRIPTION

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0039] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0040] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the present invention. The present description and examples are intended to be illustrative only.

[0041] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0042] Unless otherwise specified, all raw materials and instruments used in the following examples of the present invention are commercially available.

[0043] Collect mustard tuber wastewater and mustard tuber comprehensive wastewater: mustard tuber wastewater: includes mustard tuber rough processing wastewater, mustard tuber first pickling wastewater, second pickling wastewater, third pickling wastewater, etc.; mustard tuber comprehensive wastewater: includes wastewater generated by washing, cutting, desalting, dehydration, mixing, sterilization, ground and equipment flushing processes.

[0044] Example 1

[0045] The quality of the wastewater sampled: COD in mustard wastewater (pickled wastewater) Cr About 34500mg / L, total nitrogen concentration about 1950mg / L, total phosphorus about 168mg / L, salinity about 13.56%, chloride ion about 93g / L; mustard integrated wastewater: COD Cr About 3730 mg / L, total nitrogen concentration is about 123 mg / L, total phosphorus is about 32 mg / L, salinity is about 2.78%, and chloride ion is 10.8 g / L.

[0046] After the mustard tuber wastewater (pickled wastewater) is mixed with the mustard tuber comprehensive wastewater, the COD of the wastewater in the regulating pool is about 4627 mg / L, the total nitrogen concentration is about 177 mg / L, the total phosphorus concentration is 36 mg / L, the salinity is 3.1%, and the chloride ion is 13.19 g / L.

[0047] According to Figure 1 The process method described.

[0048] The mustard wastewater is discharged into the screen channel in front of the mustard wastewater regulating tank. The impurities in the wastewater (such as vegetable residues, fiber stems, etc.) are intercepted by mechanical screens, and the wastewater is discharged into the regulating tank. A liquid level meter is installed in the regulating tank, and the wastewater is quantitatively sent to the comprehensive regulating tank through a lifting pump.

[0049] The mustard tuber comprehensive wastewater is discharged into the screen channel in front of the comprehensive wastewater regulating tank. The impurities in the wastewater (such as vegetable residues, fiber stems, etc.) are intercepted by mechanical screens, and the wastewater is discharged into the comprehensive regulating tank. The regulating tank is equipped with a liquid level meter and a stirring system. The wastewater is homogenized and mixed in an equal volume ratio of 3:100 between the mustard tuber wastewater and the mustard tuber comprehensive wastewater. The wastewater to be treated is sent to the high-temperature wet oxidation system through a water pump.

[0050] In the high-temperature wet oxidation system, wastewater is controlled at a temperature of 500°C and a pressure of 50 atm. Under these high-temperature and high-pressure conditions, organic matter in the water undergoes an oxidative decomposition reaction, completely oxidizing complex organic pollutants such as benzene series and nitrogen compounds. The organic matter concentration gradually decreases, ultimately degrading the pollutants. The effluent from the high-temperature wet oxidation system is fed to coagulation and sedimentation system 1.

[0051] The coagulation and sedimentation system 1, under the automatic monitoring of the pH meter, adds alkali solution to keep the pH of the wastewater in an alkaline environment of 8. At the same time, the coagulant PAC is added to remove suspended matter and phosphorus compounds in the wastewater, and the suspended matter and pollutants in the water are gradually aggregated to form large suspended particles through bridging, electrical neutralization and netting. Under hydraulic flow, the flocculant PAM is then added to adsorb suspended particles in the water, play a linking and bridging role between the particles, so that fine particles form relatively large flocs, and accelerate the precipitation of particles. Under hydraulic flow, the wastewater effluent enters the sedimentation area, and the supernatant in the sedimentation area flows to the intermediate water tank 1, and the sludge at the bottom of the sedimentation tank is discharged to the sludge tank.

[0052] The wastewater in the intermediate pool 1 is dosed with acidic agents through a dosing pump to adjust the pH to 4. The wastewater is lifted by a lifting pump and enters the three-dimensional electrolytic reaction device to control the pH to 5. The plate spacing is 20 cm and the current density is 30 mA / cm 2 , with an effective residence time of 1.5 hours, using the high potential of the electrochemical anode of the three-dimensional electrolysis to directly oxidize and destroy macromolecular organic matter in the wastewater, removing some COD and ammonia nitrogen in the wastewater. The effluent from the three-dimensional electrolysis system is sent to the coagulation and sedimentation system 2;

[0053] In the coagulation and sedimentation system 2, under the automatic monitoring of the pH meter, alkali solution is added to keep the wastewater pH in an alkaline environment of about 7.5 to 9.5, and neutralization aeration is performed for 0.5 to 1 hour. At the same time, coagulant PAC and flocculant PAM are added. Finally, the pollutants are precipitated and removed in the form of sludge in the sedimentation area. The supernatant in the sedimentation area flows into the intermediate water tank 2 by gravity, and the sludge at the bottom of the sedimentation tank is discharged into the sludge tank.

[0054] A lifting pump is installed inside the intermediate water tank 2, and the wastewater is lifted to the denitrification oxidation tank by the lifting pump. At the same time, high-efficiency special denitrification microbial strains (from commercial sources) are added to directly degrade ammonia nitrogen into nitrogen (N2) without consuming the carbon source (BOD). This not only removes ammonia nitrogen, but also reduces the total nitrogen index, which is beneficial to the efficiency of the subsequent treatment. The effluent from the aeration denitrification system is lifted to the ozone catalytic oxidation system.

[0055] The wastewater is deeply treated in the ozone catalytic oxidation system with an ozone dosage of 300 mg / L. The strong oxidizing properties of O3 and the efficient catalytic activity of the catalyst are used to further oxidize and decompose the residual difficult-to-degrade organic matter in the wastewater, and decolorize it at the same time to ensure that the final effluent meets the feed requirements of the material membrane. Overall, it can also improve the purity of the ion membrane feed liquid product.

[0056] A lift pump is installed inside intermediate tank 3, which lifts wastewater to the de-materializing membrane. The de-materializing membrane retains pollutants, but not salts. The retained wastewater meets discharge requirements. The salty wastewater meets the feed requirements for the ion exchange membrane and becomes the product.

[0057] The sludge in the sludge pool is dehydrated, bagged, and regularly outsourced for treatment.

[0058] Experimental example

[0059] Wastewater discharged after treatment: wastewater COD <100mg / L, removal rate up to 99.9%; total nitrogen concentration is about <1mg / L, removal rate up to 97%; total phosphorus <0.1mg / L, removal rate up to 99.8%. Salinity <0.1%, chloride ion <0.5g / L.

[0060] In addition, the material membrane concentrated water: COD about 209 mg / L, total nitrogen concentration about 3 mg / L, total phosphorus about 1 mg / L, salinity 14.8%, chloride ion 63 g / L, can become the product ion membrane feed liquid.

[0061] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for treating mustard tuber wastewater and recycling resources, characterized in that: The following steps are involved: S1. The mustard tuber wastewater and the mustard tuber comprehensive wastewater are mixed after being passed through a screen to intercept suspended pollutants to obtain the wastewater to be treated; S2. The wastewater to be treated is treated by a high-temperature wet oxidation system to obtain a first treated wastewater; S3. The low organic matter concentration wastewater is treated by a first coagulation and sedimentation system to obtain a second treated wastewater and a first precipitated sludge; S4. The second treated wastewater is adjusted to a pH of 3 to 6 and then subjected to three-dimensional electrolysis to obtain a third treated wastewater; S5. The third treated wastewater is treated by a second coagulation and sedimentation system to obtain a fourth treated wastewater and a second precipitated sludge; S6. Adding denitrifying microorganisms to the fourth treated wastewater for treatment to obtain a fifth treated wastewater; S7. The fifth treated wastewater is subjected to an ozone catalytic oxidation system for deep treatment and then filtered through a material membrane to obtain the sixth treated wastewater.

2. The method for treating mustard tuber wastewater and recycling resources according to claim 1, characterized in that: The S1 mustard wastewater contains COD Cr 30000~40000mg / L, total nitrogen concentration 1500~2500mg / L, total phosphorus 150~200mg / L, salinity 10~15%, chloride ion 60~100g / L; mustard integrated wastewater: COD Cr 3000~4000mg / L, total nitrogen concentration 200~300mg / L, total phosphorus 25~40mg / L, salinity 2~3%, chloride ion 7~13g / L.

3. The method for treating mustard tuber wastewater and recycling resources according to claim 1, characterized in that: The volume ratio of the mustard tuber wastewater to the mustard tuber comprehensive wastewater in S1 is (3-4):

100.

4. The method for treating mustard tuber wastewater and recycling resources according to claim 1, characterized in that: The treatment method of the S2 medium- and high-temperature wet oxidation system is: under high temperature and high pressure, the organic matter in the wastewater is oxidized into carbon dioxide and water using oxygen in the air as an oxidant; the temperature is controlled at 450-600°C, and the pressure is controlled at 20-200atm.

5. The method for treating mustard tuber wastewater and recycling resources according to claim 1, characterized in that: The treatment method of the first coagulation and sedimentation system in S3 is: adjusting the pH of the wastewater to 7.5-9.5 and adding coagulant PAC at the same time.

6. The method for treating mustard tuber wastewater and recycling resources according to claim 1, characterized in that: The three-dimensional electrolysis parameters in S4 are as follows: pH 4-6, plate spacing 5-30 cm, current density 10-50 mA / cm 2 , effective stay time is 1 to 2 hours.

7. The method for treating mustard tuber wastewater and recycling resources according to claim 1, characterized in that: The treatment method of the second coagulation and sedimentation system in S5 is: adjusting the wastewater pH to maintain at 7.5-9.5, then neutralizing and aerating for 0.5-1 hour; and simultaneously adding coagulant PAC and flocculant PAM.

8. The method for treating mustard tuber wastewater and recycling resources according to claim 1, characterized in that: The denitrifying microorganisms in S6 are autotrophic short-range nitrifying and denitrifying microorganisms and salt-tolerant special denitrifying bacteria.

9. The method for treating mustard tuber wastewater and recycling resources according to claim 1, characterized in that: The ozone catalytic oxidation system treatment method in S7 is: utilizing the strong oxidizing property of O3 and the efficient catalytic activity of the catalyst, the organic matter undergoes oxidation reaction on the catalyst surface, and the ozone dosage is 100-500 mg / L.

10. The method for treating mustard tuber wastewater and recycling resources according to claim 1, characterized in that: The membrane used for the material membrane filtration in S7 is a material membrane that only allows water molecules to pass through and retains salt.

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