A pesticide wastewater treatment method based on degassing membrane coupling Fenton-like technology
By using degassing membrane coupling Fenton-like technology to treat pesticide wastewater, and utilizing inexpensive catalysts and pre-filtration processes, the problem of treating high COD and high ammonia nitrogen wastewater has been solved, achieving efficient and economical pesticide wastewater treatment results.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-22
- Publication Date
- 2026-04-03
AI Technical Summary
Existing technologies are difficult to effectively treat high COD and high ammonia nitrogen pollutants in pesticide wastewater, and the high cost and single process can easily damage the biochemical system, resulting in poor treatment effect and high cost.
The degassing membrane coupled with Fenton-like technology is adopted, which uses an external pressure degassing membrane and inexpensive ferrous sulfide and ferric sulfate to synergistically catalyze hydrogen peroxide treatment of pesticide wastewater. The combination of pre-filtration and Fenton-like reactor reduces treatment costs and improves efficiency.
It significantly reduces the concentration of COD and ammonia nitrogen in wastewater, achieving removal rates of over 90% and 85% for organic pollutants and ammonia nitrogen in pesticide production wastewater, respectively, thus reducing the burden of subsequent biochemical treatment, lowering costs, and improving treatment efficiency.
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Figure CN120817696B_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of wastewater treatment, and more specifically, it relates to a method for treating pesticide wastewater based on degassing membrane coupling Fenton-like technology. Background Technology
[0002] Pesticide wastewater has a complex composition and extremely high concentrations of organic matter and total nitrogen, with chemical oxygen demand (COD) often reaching tens of thousands of milligrams per liter (mg / L). The organic matter in pesticide wastewater is typically biodegradable and biotoxic, and most are persistent organic pollutants (POPs). These organic compounds mainly originate from intermediates and byproducts in the production process, and some pesticide wastewater also contains harmful substances such as arsenic and heavy metals. Pollutants in pesticide wastewater often remain in the environment for extended periods and can gradually accumulate in water, soil, and air, causing persistent ecological damage.
[0003] Given the characteristics of pesticide wastewater—high ammonia nitrogen, high COD, high salinity, presence of numerous recalcitrant substances, and high toxicity—the main treatment methods used both domestically and internationally include advanced oxidation technologies (such as Fenton oxidation and ozone ammonia oxidation), biological methods (such as aerobic oxidation), and anaerobic biofilm treatment technologies. However, the effluent from these processes has generally failed to eliminate pesticide residues in the wastewater.
[0004] Meanwhile, the high ammonia nitrogen and high COD characteristics of pesticide wastewater, if directly treated with biochemical methods, will damage the stability of the biochemical treatment system and may even lead to system collapse.
[0005] Extensive research and engineering practice have shown that high-cost, single-process wastewater treatment is basically unable to effectively remove pesticide residues and their intermediates from pesticide wastewater. Furthermore, single-process wastewater treatment also has disadvantages such as high cost, pollution transfer, poor effluent quality, large land area, complex management, and high construction and maintenance costs.
[0006] Therefore, developing a more efficient, economical, and environmentally friendly pesticide wastewater treatment technology has become one of the technical problems that need to be solved by those skilled in the art, given the challenges of high difficulty and cost in treating pesticide wastewater. Summary of the Invention
[0007] The purpose of this application is to provide a pesticide wastewater treatment method based on degassing membrane coupling Fenton-like technology, which can achieve efficient treatment of pesticide production wastewater by using an external pressure degassing membrane and inexpensive ferrous sulfide and ferric sulfate to synergistically catalyze hydrogen peroxide, thereby reducing treatment costs, improving treatment efficiency, and shortening the overall treatment time.
[0008] To achieve the above objectives, this application employs the following technical solution:
[0009] The pesticide wastewater treatment method based on degassing membrane coupling Fenton-like technology described in this application includes the following steps:
[0010] Step (1): Pesticide production wastewater is fed into the mother liquor tank, and the pH is adjusted to between 10 and 11 using a 2M sodium hydroxide solution in the mother liquor tank.
[0011] Step (2): The pesticide production wastewater after pH adjustment is pre-filtered through a filtration device;
[0012] Step (3): After pre-filtration, the pesticide production wastewater is injected into the bottom inlet of the column membrane reactor at a flow rate of 132 mL / min.
[0013] Step (4): 2M sulfuric acid solution in the acid storage tank is pumped in reverse through the acid inlet at the bottom of the column membrane reactor. The sulfuric acid solution retained by the column membrane reactor is returned to the acid storage tank for regeneration and reuse through the circulation pipeline.
[0014] Step (5): After the column membrane reactor has reacted for 10 minutes, measure the COD and ammonia nitrogen concentrations in the effluent of the column membrane reactor; so that the removal rate of organic matter and ammonia nitrogen can reach more than 70%, so that the subsequent Fenton-like technology can play a better role.
[0015] Step (6): The column membrane reactor sends the wastewater after the reaction is completed into the Fenton-like reactor through the outlet at the top, and slowly adds 2M sulfuric acid solution to the Fenton-like reactor until the pH of the wastewater in the Fenton-like reactor reaches 3~4, then stops adding sulfuric acid solution.
[0016] Step (7): Prepare a 1M ferric sulfate solution for later use. Crush and grind ferrous sulfide into powder with a particle size of 90 to 100 mesh. Soak the ground ferrous sulfide powder in 2mM sulfuric acid until the fresh surface of ferrous sulfide is exposed. After soaking, rinse with deionized water until there is no residual sulfuric acid solution on the surface and set aside for later use.
[0017] Step (8): Add the ferrous sulfide powder prepared in step (7) to the Fenton-like reactor in step (6). The mass concentration of ferrous sulfide in the Fenton-like reactor is not less than 2.8 g / L. At the same time, add 1 mL of 1 M ferric sulfate solution to the Fenton-like reactor in step (6).
[0018] Step (9): Place the Fenton-like reactor from step (8) into a magnetic stirrer, and set the speed of the magnetic stirrer to 1800~2000 r / min and the stirring time to 10 min;
[0019] Step (10): Add 77 mM hydrogen peroxide to the Fenton-like reactor after stirring. After the addition is completed, set the speed of the magnetic stirrer to 1800~2000 r / min and the stirring time to 60 min. Add 38.5 mM hydrogen peroxide at 15 min, 30 min and 45 min of the reaction respectively.
[0020] Step (11): Take samples at 0 min, 15 min, 30 min, 45 min and 60 min after the start of the reaction in step (10). Take 5 mL of sample and add it to a test tube containing 0.2 mL of 6M sodium hydroxide solution. Shake well to terminate the reaction.
[0021] Step (12): Centrifuge the sample from step (11) to terminate the reaction, and measure the amount of organic matter removed and the concentration of ammonia nitrogen in the pesticide production wastewater after precipitation.
[0022] Compared with the prior art, the beneficial effects of this application are:
[0023] 1. This application uses an external pressure columnar membrane coupled with Fenton-like technology to treat pesticide wastewater. This technology can significantly reduce the COD and ammonia nitrogen concentrations in the wastewater, indicating that the organic pollutants in the wastewater are effectively degraded or mineralized. Pretreatment with the columnar membrane can significantly reduce the organic load in the wastewater. The wastewater treated by the membrane technology can enable Fenton-like technology to exert its highest degradation effect. After treatment by the coupled process, the "burden" on subsequent biological treatment is reduced, so that the subsequent biological treatment will not be inhibited by the high COD and high ammonia nitrogen in the pesticide wastewater, and can better exert the removal effect.
[0024] 2. The degassing membrane used in this application has a low cost and can be reused. At the same time, ferrous sulfide and ferric sulfate are inexpensive and readily available, requiring less equipment, simple to operate, and significantly reducing treatment costs. After treating pesticide production wastewater with pressure column membrane coupled with Fenton-like technology, the removal rates of organic pollutants and ammonia nitrogen in pesticide production wastewater can reach over 90% and 85%, respectively. Attached Figure Description
[0025] Figure 1 This refers to the organic matter removal rate of Examples 1 to 4 in this application.
[0026] Figure 2 It refers to the ammonia nitrogen removal rate of Examples 1 to 4 in this application. Detailed Implementation
[0027] The technical solutions described in this application will be further described below with reference to the accompanying drawings and embodiments.
[0028] Example 1
[0029] As a comparative example, a method for treating pesticide wastewater includes the following steps:
[0030] Step (1): Take pesticide production wastewater from a material company in Gansu Province. The COD concentration of the pesticide production wastewater reaches 21,000 mg / L, the ammonia nitrogen concentration reaches 1,100 mg / L, and the pH of the pesticide production wastewater is 6.5. Inject the above pesticide production wastewater into the mother liquor tank and use 2M sodium hydroxide solution to adjust the pH of the mother liquor tank to between 10 and 11.
[0031] Step (2): The pesticide production wastewater in the mother liquor tank after pH adjustment is pre-filtered using a microfiltration device.
[0032] Step (3): The pesticide production wastewater after pre-filtration is injected into the bottom inlet of the columnar membrane reactor through a booster pump and PVC pipeline. The injection flow rate of the pesticide production wastewater is 132 mL / min.
[0033] Step (4): While injecting pesticide production wastewater into the columnar membrane reactor, the 2M sulfuric acid solution stored in the acid storage tank is pumped in reverse through the acid inlet at the bottom of the columnar membrane reactor. The sulfuric acid solution retained by the columnar membrane reactor is returned to the acid storage tank for regeneration through the circulation pipeline.
[0034] Step (5): After reacting in the column membrane reactor for 10 minutes, the removal rates of organic matter and ammonia nitrogen in the effluent of the column membrane reactor were measured. After measurement, the removal rates of organic matter and ammonia nitrogen were 71% and 81.8%, respectively.
[0035] Example 2
[0036] As another comparative example, a method for treating pesticide wastewater includes the following steps:
[0037] Step (1): Take pesticide production wastewater from a material company in Gansu Province. The COD concentration of the pesticide production wastewater reaches 21,000 mg / L, the ammonia nitrogen concentration reaches 1,100 mg / L, and the pH of the pesticide production wastewater is 6.5. Add the pesticide production wastewater to the reactor and slowly add 2M sulfuric acid solution until the pH of the pesticide wastewater in the reactor reaches 3.5, then stop adding sulfuric acid solution.
[0038] Step (2): Prepare a 1M ferric sulfate solution for later use. Crush and grind ferrous sulfate to a particle size of 90 to 100 mesh. Weigh 3.2g of the ground ferrous sulfide powder and soak it in a 2mM sulfuric acid solution until the fresh surface of the ferrous sulfide is exposed. After soaking, rinse with deionized water until there is no residual sulfuric acid solution on the surface and set aside for use.
[0039] Step (3): Add the ferrous sulfate powder processed in step (2) into the reactor in step (1), and ensure that the mass concentration of ferrous sulfate added to the reactor reaches 3.2 g / L. At the same time, add 1 mL of 1 M ferrous sulfate solution to the reactor in step (1).
[0040] Step (4): Place the reactor from step (3) in a magnetic stirrer and set the speed of the magnetic stirrer to 1800~2000 r / min and the stirring time of the magnetic stirrer to 10 min.
[0041] Step (5): After stirring, add 77 mM hydrogen peroxide to the reactor in step (4) for the first time, continue to set the speed of the magnetic stirrer to 1800~2000 r / min, set the stirring time of the magnetic stirrer to 60 min, and add 38.5 mM hydrogen peroxide at the 15 min, 30 min and 45 min of the reaction in the reactor respectively.
[0042] In step (6), samples are taken at time points of 0 min, 15 min, 30 min, 45 min and 60 min in the reactor of step (5). The 5 mL sample is added to a test tube containing 0.2 mL of 6M sodium hydroxide solution and shaken to terminate the reaction.
[0043] Step (7): Centrifuge the samples after each reaction is terminated in step (6), and measure the removal rates of organic matter and ammonia nitrogen in pesticide production wastewater after precipitation is completed. The removal rates are 51% and 57.1%, respectively.
[0044] Example 3
[0045] A method for treating pesticide wastewater based on degassing membrane coupling Fenton-like technology, the method comprising the following steps:
[0046] Step (1): Take pesticide production wastewater from a material company in Gansu Province. The COD concentration of the pesticide production wastewater reaches 21,000 mg / L, the ammonia nitrogen concentration reaches 1,100 mg / L, and the pH of the pesticide production wastewater is 6.5. Inject it into the mother liquor tank and use 2M sodium hydroxide solution to adjust the pH of the pesticide production wastewater in the mother liquor tank to between 10 and 11.
[0047] Step (2): After adjusting the pH in step (1), the pesticide production wastewater is pre-filtered through a microfiltration device.
[0048] Step (3): The pre-filtered pesticide production wastewater is injected into the inlet hole at the bottom of the column membrane reactor through a booster pump and a PVC pipe connected to the booster pump, and the injection flow rate is controlled to be 132 mL / min.
[0049] In step (4), during the process of step (3), 2M sulfuric acid solution is simultaneously pumped in reverse through the acid inlet hole at the bottom of the columnar membrane reactor. The sulfuric acid solution is stored in the acid storage tank, and the sulfuric acid solution retained by the columnar membrane reactor is returned to the acid storage tank for regeneration and reuse through the circulation pipeline.
[0050] Step (5): After the reaction in the column membrane reactor has proceeded for 10 minutes, measure the COD and ammonia nitrogen concentrations in the effluent of the column membrane reactor to ensure that the removal rate of organic matter and ammonia nitrogen reaches more than 70%, so that the subsequent Fenton-like technology can play a better role.
[0051] Step (6): The pesticide production wastewater treated by the column membrane reactor enters the Fenton-like reactor through the outlet of the column membrane reactor, and 2M sulfuric acid solution is slowly added until the pH value of the pesticide production wastewater in the Fenton-like reactor reaches 3 to 4 as measured by a pH meter, and then the addition of sulfuric acid solution is stopped.
[0052] Step (7): Prepare a 1M ferric sulfate solution for later use, and crush and grind ferrous sulfide into powder with a particle size of 90 to 100 mesh. After grinding, soak the ferrous sulfide powder in a 2M sulfuric acid solution until the fresh surface of ferrous sulfide is exposed, and then rinse it with deionized water until there is no residual sulfuric acid solution on the surface before use.
[0053] Step (8): Add the ferrous sulfide powder processed in step (7) to the Fenton-like reactor in step (6), and ensure that the ferrous sulfide mass concentration in the Fenton-like reactor reaches 2.8 g / L. At the same time, add 1 mL of 1 M ferric sulfate solution to the Fenton-like reactor in step (6).
[0054] In step (9), the Fenton-like reactor in step (8) is placed in a magnetic stirrer, and the speed of the magnetic stirrer is set to 1800~2000 r / min, and the stirring time is set to 10 min.
[0055] Step (10): Add ferric sulfate solution and ferrous sulfide powder to the Fenton-like reactor after stirring in step (9), and add 77 mM hydrogen peroxide for the first time. Set the speed of the magnetic stirrer to 1800~2000 r / min, the stirring time to 60 min, and add 38.5 mM hydrogen peroxide at the 15 min, 30 min and 45 min of stirring, respectively.
[0056] In step (11), samples are taken at 0 min, 15 min, 30 min, 45 min and 60 min after the start of the reaction in step (10). 5 mL of sample is taken and added to a test tube containing 0.2 mL of 6M sodium hydroxide solution. The sample is then shaken to terminate the reaction.
[0057] Step (12): After the reaction was terminated in step (11), the sample was centrifuged and the removal of organic matter and ammonia nitrogen in the pesticide production wastewater was measured after precipitation. The results were 91.6% and 86.3%, respectively.
[0058] Example 4
[0059] A pesticide wastewater treatment method based on degassing membrane coupling Fenton-like technology differs from the technical solution described in Example 3 in that the ferrous sulfide powder added in step (8) forms a Fenton-like reactor with a mass concentration of 3.2 g / L. The remaining implementation steps or methods are the same as those described in Example 3.
[0060] After the reaction was terminated, the sample was centrifuged and the removal rates of organic matter and ammonia nitrogen in the pesticide production wastewater were measured after precipitation. The results were 92.1% and 87.1%, respectively.
[0061] In the above embodiments, the pretreated pesticide production wastewater enters the columnar membrane reactor through the bottom inlet hole. Through the synergistic effect of the water distribution pipe and the flow guide baffle inside the columnar membrane reactor, uniform turbulence is formed inside the columnar membrane reactor, which enhances the gas-liquid mass transfer efficiency.
[0062] In the above embodiments, the columnar membrane reactor can achieve physical isolation from the alkaline raw water through its internal hydrophobic hollow fiber degassing membrane, and the sulfuric acid solution retained by the hollow fiber degassing membrane can be returned to the acid storage tank for regeneration through the circulation pipeline.
[0063] As seen in Examples 1 and 2 above, single membrane separation reactions and Fenton-like technologies are not ideal for treating pesticide production wastewater. This is mainly because while single membrane separation technology can retain most organic pollutants, the high COD load and high ammonia nitrogen content in pesticide production wastewater mean that membrane separation technology cannot completely remove all organic pollutants. Secondly, single Fenton-like technologies have many problems. The complex composition and high levels of organic pollutants and ammonia nitrogen in pesticide production wastewater can quench free radicals in the Fenton-like reaction process, inhibiting the Fenton-like reaction and thus reducing the degradation efficiency of organic matter.
[0064] However, as we can see from Examples 3 and 4, the degassing membrane technology coupled with Fenton-like technology achieves a treatment efficiency of over 90% and over 85% for pesticide production wastewater. This is because the degassing membrane technology intercepts most of the organic pollutants and ammonia nitrogen in advance, while the Fenton-like technology makes up for the incomplete treatment of the degassing membrane separation technology. The two complement each other and improve the overall treatment effect of pesticide production wastewater.
[0065] This application employs a pretreatment based on degassing membrane separation technology. By pretreating pesticide wastewater with high COD and high ammonia nitrogen, the extremely high load in pesticide production wastewater can be reduced, alleviating the burden on subsequent treatment and improving the treatment efficiency of pesticide production wastewater.
[0066] During the degassing membrane treatment stage, the organic matter contained in pesticide production wastewater is retained when it passes through the degassing membrane, while ammonia nitrogen (NH3-N) can be converted into free NH3 molecules after being activated by hot alkali. Driven by the transmembrane partial pressure gradient, NH3 molecules selectively penetrate the membrane pores to the sulfuric acid absorption phase side and undergo a protonation reaction to regenerate ammonium salts. As a result, the concentration of organic matter and ammonia nitrogen contained in pesticide production wastewater is significantly reduced during the degassing membrane treatment stage.
[0067] In the Fenton-like reaction technique of this application, the ferrous sulfide (FeS) used mainly exists in nature as a mineral. It can efficiently reduce highly toxic Cr(VI), and ferrous sulfide also plays an important role in continuously releasing Fe under acidic conditions. 2+ At the same time, it efficiently reduces Fe 3+ To regenerate Fe 2+ .
[0068] In the Fenton-like reaction, ferric sulfate (Fe2(SO4)3) plays a dual role: firstly, it provides the initial Fe... 3+ To promote rapid reaction initiation and shorten the induction period, and secondly, the introduced Fe 3+ Fe produced by the continuous reduction of FeS 2+ Synergistic effect, constructing and enhancing Fe 3+ / Fe 2+ Iron cycling significantly improves catalytic efficiency and system sustainability.
[0069] The membrane coupling Fenton technology described in this application can effectively overcome the defects and shortcomings of other technologies in the process of treating pesticide production wastewater, significantly improve the treatment efficiency of pesticide production wastewater, reduce the treatment cost of pesticide production wastewater, and thus shorten the overall treatment time of pesticide production wastewater.
[0070] Finally, although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.
Claims
1. A method for treating pesticide wastewater based on degassing membrane coupling Fenton-like technology, characterized in that, The method includes the following steps: Step (1): Pesticide production wastewater is fed into the mother liquor tank, and the pH is adjusted to between 10 and 11 using a 2M sodium hydroxide solution in the mother liquor tank. Step (2): The pesticide production wastewater after pH adjustment is pre-filtered through a filtration device; Step (3): After pre-filtration, the pesticide production wastewater is injected into the bottom inlet of the column membrane reactor at a flow rate of 132 ml / min. Step (4): 2M sulfuric acid solution in the acid storage tank is pumped in reverse through the acid inlet at the bottom of the column membrane reactor. The sulfuric acid solution retained by the column membrane reactor is returned to the acid storage tank for regeneration and reuse through the circulation pipeline. Step (5): After the column membrane reactor has reacted for 10 minutes, measure the COD and ammonia nitrogen concentrations in the effluent of the column membrane reactor; so that the removal rate of organic matter and ammonia nitrogen can reach more than 70%, so that the subsequent Fenton-like technology can play a better role. Step (6): The column membrane reactor sends the wastewater after the reaction is completed into the Fenton-like reactor through the outlet at the top, and slowly adds 2M sulfuric acid solution to the Fenton-like reactor until the pH of the wastewater in the Fenton-like reactor reaches 3~4, then stops adding sulfuric acid solution. Step (7): Prepare a 1M ferric sulfate solution for later use. Crush and grind ferrous sulfide into powder with a particle size of 90 to 100 mesh. Soak the ground ferrous sulfide powder in 2mM sulfuric acid until the fresh surface of ferrous sulfide is exposed. After soaking, rinse with deionized water until there is no residual sulfuric acid solution on the surface and set aside for later use. Step (8): Add the ferrous sulfide powder prepared in step (7) to the Fenton-like reactor in step (6). The mass concentration of ferrous sulfide in the Fenton-like reactor is not less than 2.8 g / L. At the same time, add 1 ml of 1 M ferric sulfate solution to the Fenton-like reactor in step (6). Step (9): Place the Fenton-like reactor from step (8) into a magnetic stirrer, and set the speed of the magnetic stirrer to 1800~2000 r / min and the stirring time to 10 min; Step (10): Add 77 mM hydrogen peroxide to the Fenton-like reactor after stirring. After the addition is completed, set the speed of the magnetic stirrer to 1800~2000 r / min and the stirring time to 60 min. Add 38.5 mM hydrogen peroxide at 15 min, 30 min and 45 min of the reaction respectively. Step (11): Take samples at 0 min, 15 min, 30 min, 45 min and 60 min after the start of the reaction in step (10). Take 5 mL of sample and add it to a test tube containing 0.2 mL of 6M sodium hydroxide solution. Shake well to terminate the reaction. Step (12): Centrifuge the sample from step (11) to terminate the reaction, and measure the amount of organic matter removed and the concentration of ammonia nitrogen in the pesticide production wastewater after precipitation.
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