A method for treating phenol-containing wastewater

Abstract

This invention belongs to the field of wastewater treatment technology, specifically relating to a method for treating phenol-containing wastewater. The preparation method includes: homogenization, cyanide removal, carbon dioxide flotation, anaerobic reaction, and sedimentation. In this method, the upper openings of the equalization tank, cyanide removal reactor, and carbon dioxide flotation tank are all equipped with sealing covers. These sealing covers minimize the contact between wastewater and air. Furthermore, the carbon dioxide flotation process uses carbon dioxide as the flotation carrier, which increases the stirring effect on the wastewater and prevents air from entering, further preventing phenol oxidation. The anaerobic reaction process is mostly carried out under anaerobic conditions, further preventing phenol oxidation. Using this method to treat phenol-containing wastewater, the COD removal rate is ≥80%. Subsequent processes can use a two-stage A / O process, eliminating the need for adsorption by activated carbon or activated coke. This reduces wastewater treatment operating costs by eliminating the need for adding activated carbon or activated coke and the disposal costs associated with hazardous activated carbon waste.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a method for treating phenol-containing wastewater. Background Technology

[0002] In the coal chemical and coking industries, the current common pretreatment method for phenol-containing wastewater is: "equalization tank + pH adjustment + cyanide removal + hydrolysis acidification + secondary A / O + post-coagulation (addition of activated coke or activated carbon)". During the existing pretreatment process, some phenols in the wastewater are oxidized to quinones by the air. After COD degradation by the existing pretreatment process, the COD removal rate is ≤50%, and the total phenol content remains high, making subsequent pollutant degradation difficult. Due to the lack of proper pretreatment, subsequent processes incur significant costs to compensate for the inadequate pretreatment, leading to the extensive use of inorganic materials such as activated carbon and activated coke to adsorb organic matter in the wastewater. Once adsorption is saturated, the inorganic materials need to be removed from the wastewater and treated as hazardous waste after pressure filtration. This not only wastes resources but also generates a large amount of hazardous waste, significantly increasing operating costs and environmental pressure. Summary of the Invention

[0003] The purpose of this invention is to provide a method for treating phenol-containing wastewater to solve the technical problems mentioned in the background section.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a method for treating phenol-containing wastewater, the method comprising the following steps:

[0005] Step 1: Homogenization

[0006] Wastewater is fed into a regulating tank for homogenization treatment;

[0007] Step 2: Cyanide Removal

[0008] The wastewater homogenized in step 1 is fed into the cyanide removal reactor. Sodium hydroxide is added to adjust the wastewater to alkalinity in the reactor, and then cyanide removal agent is added. After the reaction, acid is added to adjust the pH value of the wastewater. After sedimentation, the wastewater is discharged.

[0009] Step 3: Carbon dioxide flotation

[0010] The wastewater after cyanide removal in step 2 is fed into a carbon dioxide flotation tank. Carbon dioxide is used as the flotation carrier to separate water-insoluble organic matter from the wastewater, which is then scraped to a crude phenol tank by a scraper. In the carbon dioxide flotation tank, carbon dioxide combines with sodium ions to form sodium bicarbonate. Phenolic organic matter has low solubility in sodium bicarbonate solution, so it floats to the surface of the liquid during the flotation process, further removing phenolic organic matter from the wastewater.

[0011] Step 4: Anaerobic reaction

[0012] The wastewater after carbon dioxide flotation in step 3 is fed into an anaerobic reactor. Nutrients are added to the anaerobic reactor, and the wastewater temperature is controlled at 30-40℃ and the wastewater pH value is controlled at 7-8. The wastewater undergoes anaerobic reaction, and the biogas produced is introduced into a biogas treatment system.

[0013] Step 5: Precipitation

[0014] The wastewater after the anaerobic reaction in step 4 is fed into an anaerobic sedimentation tank, where it settles and is then discharged.

[0015] Preferably, the cyanide removal reactor includes a first coagulation tank, a second coagulation tank, a third coagulation tank, and a cyanide removal sedimentation tank. Wastewater homogenized in the equalization tank enters from the top of the first coagulation tank. Simultaneously, sodium hydroxide is added at the inlet to adjust the wastewater pH to 9.5-10. The wastewater flows out from the bottom of the first coagulation tank and simultaneously flows by gravity into the second coagulation tank. A cyanide removal agent is added to the second coagulation tank, and after reacting for 30-90 minutes, a stable complex is formed. The wastewater then flows by gravity from the top of the second coagulation tank to the third coagulation tank. Simultaneously, acid is added to the third coagulation tank to adjust the pH to 8-. 9. The complex is rapidly precipitated to separate cyanide from the wastewater. The wastewater flows by gravity from the middle of the third coagulation tank to the cyanide removal sedimentation tank. After sedimentation, the wastewater is discharged from the effluent weir of the sedimentation tank. The first, second, and third coagulation tanks are all equipped with agitators and dosing systems as used in the prior art. In the cyanide removal reactor, the addition of sodium hydroxide adjusts the wastewater to an alkaline environment to facilitate the subsequent cyanide removal steps. Sodium hydroxide and cyanide removal agent are added sequentially in different coagulation tanks to avoid interference from sodium hydroxide on the cyanide removal agent, thereby effectively ensuring the stable formation of the complex.

[0016] Preferably, the anaerobic reactor includes an inlet tank, an anaerobic tank, and an anaerobic sedimentation tank. The inlet tank is equipped with a stirrer, a nutrient salt addition port, a pH adjustment port, and a steam heater. Wastewater treated by carbon dioxide flotation flows into the inlet tank by gravity from the top. Nutrient salts are added to the inlet tank, and the water temperature is controlled at 35-40℃ and the pH is controlled at 7-8. The wastewater is discharged from the bottom of the inlet tank and pumped into the anaerobic tank. Anaerobic reaction takes place in the anaerobic tank, and the biogas produced is introduced into the biogas treatment system and discharged from the top of the anaerobic tank. The wastewater flows into the anaerobic sedimentation tank by gravity from the lower part of the anaerobic tank. After sedimentation, solid-liquid separation occurs, and the wastewater is discharged from the effluent weir at the top of the anaerobic sedimentation tank.

[0017] Preferably, the upper openings of the equalization tank, the cyanide removal reactor, and the carbon dioxide flotation tank are all equipped with sealing covers.

[0018] Preferably, the regulating tank is a concrete structure, a fiberglass structure, or a steel structure, and the manhole of the regulating tank is sealed.

[0019] Preferably, the phenol-containing wastewater is discharged into the equalization tank after preliminary ammonia stripping and phenol removal treatment.

[0020] Preferably, the anaerobic reactor is equipped with a total phenol sampling tube, with a total number of five sampling tubes. Samples are taken from the sampling tubes at different locations to observe the degradation of phenol at different stages.

[0021] Preferably, the wastewater after sedimentation in step 5 is introduced into a secondary A / O wastewater treatment process for further treatment.

[0022] Preferably, the sedimentation time of the wastewater in the cyanide removal sedimentation tank is 30 minutes.

[0023] Preferably, a pump is installed between the equalization tank, the cyanide removal reactor, and the carbon dioxide flotation tank, and a pump is installed between the inlet tank and the anaerobic tank.

[0024] The beneficial effects of this invention are:

[0025] (1) The cyanide-containing wastewater is pre-treated by setting up a cyanide removal reactor. The cyanide removal reactor includes a first coagulation tank, a second coagulation tank, a third coagulation tank, and a cyanide removal sedimentation tank. The wastewater, after being homogenized in the equalization tank, enters from the top of the first coagulation tank. At the same time, sodium hydroxide is added at the inlet to adjust the pH value of the wastewater. The wastewater flows out from the bottom of the first coagulation tank and flows into the second coagulation tank by gravity. A cyanide removal agent is added to the second coagulation tank to form a stable complex. The wastewater flows by gravity from the top of the second coagulation tank to the third coagulation tank. At the same time, acid is added to the third coagulation tank to adjust the pH so that the complex can precipitate quickly to separate the cyanide ions in the wastewater. The wastewater flows by gravity from the middle of the third coagulation tank to the cyanide removal sedimentation tank. After sedimentation, the wastewater is discharged from the effluent weir of the sedimentation tank. In the cyanide removal reactor, the addition of sodium hydroxide adjusts the wastewater to an alkaline environment to facilitate the subsequent cyanide removal steps. Sodium hydroxide and cyanide removal agent are added sequentially in different coagulation tanks to avoid interference of sodium hydroxide with the cyanide removal agent, thereby effectively ensuring the stable formation of the complex.

[0026] (2) By setting up a carbon dioxide flotation tank, phenolic organic matter in phenol-containing wastewater is specifically removed. In the carbon dioxide flotation tank, carbon dioxide is used as a flotation carrier to combine with sodium ions to form sodium bicarbonate. Phenolic organic matter has low solubility in sodium bicarbonate solution, so it floats to the surface of the liquid during the flotation process. The coarse powder produced in this method has certain utilization value and further removes phenolic organic matter in wastewater. Carbon dioxide is the exhaust gas of the factory. Direct discharge will affect the atmospheric environment and lead to the greenhouse effect. This method turns carbon dioxide in the factory exhaust gas into a valuable resource, reduces environmental pollution, and can achieve carbon neutrality, achieving a double benefit.

[0027] (3) By setting up an anaerobic reactor, organic matter in phenol-containing wastewater is further removed. The anaerobic reactor includes an inlet tank, an anaerobic tank, and an anaerobic sedimentation tank. The wastewater undergoes anaerobic reaction in the anaerobic tank, and the biogas produced is introduced into the biogas treatment system from the top of the anaerobic tank. The biogas produced by this method has comprehensive utilization value and is conducive to carbon emission reduction.

[0028] (4) The upper openings of the equalization tank, the cyanide removal reactor and the carbon dioxide flotation tank are all equipped with sealing covers. In the pretreatment process of phenol-containing wastewater, the sealing covers minimize the contact between the wastewater and the air. In the carbon dioxide flotation process in step 3, carbon dioxide is used as the flotation carrier, which not only increases the stirring effect of the wastewater but also prevents air from entering, thus further preventing the oxidation of phenol. The anaerobic reaction process in step 4 is mostly carried out under anaerobic conditions, which further prevents the oxidation of phenol.

[0029] Using the method of this invention to treat phenol-containing wastewater, the COD removal rate is ≥80%. Subsequent processes can employ a two-stage A / O process, eliminating the need for adsorption by inorganic materials such as activated carbon or activated coke. This reduces wastewater treatment operating costs by eliminating the need for adding activated carbon or activated coke and the disposal costs associated with hazardous activated carbon waste. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the process for treating phenol-containing wastewater according to the present invention. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1:

[0033] Step 1: Homogenization

[0034] Wastewater is fed into a regulating tank for homogenization treatment;

[0035] Step 2: Cyanide Removal

[0036] The wastewater homogenized in step 1 is fed into the cyanide removal reactor. Sodium hydroxide is added to adjust the wastewater to alkalinity within the reactor, followed by the addition of cyanide removal agents. After the reaction, acid is added to adjust the pH value, and the wastewater is discharged after sedimentation. The specific process includes: the cyanide removal reactor comprises a first coagulation tank, a second coagulation tank, a third coagulation tank, and a cyanide removal sedimentation tank. The wastewater homogenized in the equalization tank enters from the top of the first coagulation tank, where sodium hydroxide is added to adjust the pH to 9.5. The wastewater flows out from the bottom of the first coagulation tank and simultaneously flows by gravity into the second coagulation tank. A cyanide removal agent is added to the second coagulation tank, and after reacting for 30 minutes, a stable complex is formed. The wastewater flows by gravity from the top of the second coagulation tank to the third coagulation tank. At the same time, acid is added to the third coagulation tank to adjust the pH to 8, causing the complex to precipitate rapidly and separating the cyanide ions in the wastewater. The wastewater flows by gravity from the middle of the third coagulation tank to the cyanide removal sedimentation tank, where it settles for 30 minutes. After sedimentation, the wastewater is discharged from the effluent weir of the sedimentation tank. The first, second, and third coagulation tanks are all equipped with agitators and dosing systems as used in the prior art.

[0037] Step 3: Carbon dioxide flotation

[0038] The wastewater after cyanide removal in step 2 is fed into a carbon dioxide flotation tank. Carbon dioxide is used as the flotation carrier to separate water-insoluble organic matter from the wastewater, which is then scraped to a crude phenol tank by a scraper. In the carbon dioxide flotation tank, carbon dioxide combines with sodium ions to form sodium bicarbonate. Phenolic organic matter has low solubility in sodium bicarbonate solution, so it floats to the surface of the liquid during the flotation process, further removing phenolic organic matter from the wastewater.

[0039] Step 4: Anaerobic reaction

[0040] The wastewater after carbon dioxide flotation in step 3 is fed into an anaerobic reactor. Nutrients are added to the anaerobic reactor, and the wastewater temperature is controlled at 30℃ and the pH value is controlled at 7. The wastewater undergoes an anaerobic reaction, and the biogas produced is introduced into a biogas treatment system. The specific process includes: the anaerobic reactor includes an inlet tank, an anaerobic tank, and an anaerobic sedimentation tank. The inlet tank is equipped with a stirrer, a nutrient salt addition port, a pH adjustment port, and a steam heater. The wastewater after carbon dioxide flotation treatment flows in by gravity from the top of the inlet tank. Nutrients are added to the inlet tank, and the water temperature is controlled at 30℃ and the pH is controlled at 7. The wastewater is discharged from the bottom of the inlet tank and pumped into the anaerobic tank. The anaerobic reaction takes place in the anaerobic tank, and the biogas produced is introduced into the biogas treatment system. The wastewater flows by gravity from the lower part of the anaerobic tank into the anaerobic sedimentation tank. After sedimentation, solid-liquid separation occurs, and the wastewater is discharged from the effluent weir at the top of the anaerobic sedimentation tank.

[0041] Step 5: Precipitation

[0042] The wastewater after the anaerobic reaction in step 4 is fed into an anaerobic sedimentation tank, where it settles and is then discharged.

[0043] Example 2:

[0044] Step 1: Homogenization

[0045] Wastewater is fed into a regulating tank for homogenization treatment;

[0046] Step 2: Cyanide Removal

[0047] The wastewater homogenized in step 1 is fed into a cyanide removal reactor. Sodium hydroxide is added to adjust the wastewater to alkalinity within the reactor, followed by the addition of a cyanide removal agent. After the reaction, acid is added to adjust the pH value, and the wastewater is discharged after sedimentation. The specific process includes: the cyanide removal reactor comprises a first coagulation tank, a second coagulation tank, a third coagulation tank, and a cyanide removal sedimentation tank. The wastewater homogenized in the equalization tank enters from the top of the first coagulation tank, where sodium hydroxide is added to adjust the pH to 10. The wastewater flows out from the bottom of the first coagulation tank and simultaneously flows by gravity into the second coagulation tank. A cyanide removal agent is added to the second coagulation tank, and after reacting for 60 minutes, a stable complex is formed. The wastewater flows by gravity from the top of the second coagulation tank to the third coagulation tank. At the same time, acid is added to the third coagulation tank to adjust the pH to 8, causing the complex to precipitate rapidly and separating the cyanide ions in the wastewater. The wastewater flows by gravity from the middle of the third coagulation tank to the cyanide removal sedimentation tank, where it settles for 30 minutes. After sedimentation, the wastewater is discharged from the effluent weir of the sedimentation tank. The first, second, and third coagulation tanks are all equipped with agitators and dosing systems as used in the prior art.

[0048] Step 3: Carbon dioxide flotation

[0049] The wastewater after cyanide removal in step 2 is fed into a carbon dioxide flotation tank. Carbon dioxide is used as the flotation carrier to separate water-insoluble organic matter from the wastewater, which is then scraped to a crude phenol tank by a scraper. In the carbon dioxide flotation tank, carbon dioxide combines with sodium ions to form sodium bicarbonate. Phenolic organic matter has low solubility in sodium bicarbonate solution, so it floats to the surface of the liquid during the flotation process, further removing phenolic organic matter from the wastewater.

[0050] Step 4: Anaerobic reaction

[0051] The wastewater after carbon dioxide flotation in step 3 is fed into an anaerobic reactor. Nutrients are added to the anaerobic reactor, and the wastewater temperature is controlled at 35℃ and the pH value is controlled at 7. The wastewater undergoes an anaerobic reaction, and the biogas produced is introduced into a biogas treatment system. The specific process includes: the anaerobic reactor includes an inlet tank, an anaerobic tank, and an anaerobic sedimentation tank. The inlet tank is equipped with a stirrer, a nutrient salt addition port, a pH adjustment port, and a steam heater. The wastewater after carbon dioxide flotation treatment flows in by gravity from the top of the inlet tank. Nutrients are added to the inlet tank, and the water temperature is controlled at 35℃ and the pH is controlled at 7. The wastewater is discharged from the bottom of the inlet tank and pumped into the anaerobic tank. The anaerobic reaction takes place in the anaerobic tank, and the biogas produced is introduced into the biogas treatment system. The wastewater flows by gravity from the lower part of the anaerobic tank into the anaerobic sedimentation tank. After sedimentation, solid-liquid separation occurs, and the wastewater is discharged from the effluent weir at the top of the anaerobic sedimentation tank.

[0052] Step 5: Precipitation

[0053] The wastewater after the anaerobic reaction in step 4 is fed into an anaerobic sedimentation tank, where it settles and is then discharged.

[0054] Example 3:

[0055] Step 1: Homogenization

[0056] Wastewater is fed into a regulating tank for homogenization treatment;

[0057] Step 2: Cyanide Removal

[0058] The wastewater homogenized in step 1 is fed into a cyanide removal reactor. Sodium hydroxide is added to adjust the wastewater to alkalinity within the reactor, followed by the addition of a cyanide removal agent. After the reaction, acid is added to adjust the pH value, and the wastewater is discharged after sedimentation. The specific process includes: the cyanide removal reactor comprises a first coagulation tank, a second coagulation tank, a third coagulation tank, and a cyanide removal sedimentation tank. The wastewater homogenized in the equalization tank enters from the top of the first coagulation tank, where sodium hydroxide is added to adjust the pH to 10. The wastewater flows out from the bottom of the first coagulation tank and simultaneously flows by gravity into the second coagulation tank. A cyanide removal agent is added to the second coagulation tank, and after reacting for 90 minutes, a stable complex is formed. The wastewater flows by gravity from the top of the second coagulation tank to the third coagulation tank. At the same time, acid is added to the third coagulation tank to adjust the pH to 9, causing the complex to precipitate rapidly and separating the cyanide ions from the wastewater. The wastewater flows by gravity from the middle of the third coagulation tank to the cyanide removal sedimentation tank, where it settles for 30 minutes. After sedimentation, the wastewater is discharged from the effluent weir of the sedimentation tank. The first, second, and third coagulation tanks are all equipped with agitators and dosing systems as used in the prior art.

[0059] Step 3: Carbon dioxide flotation

[0060] The wastewater after cyanide removal in step 2 is fed into a carbon dioxide flotation tank. Carbon dioxide is used as the flotation carrier to separate water-insoluble organic matter from the wastewater, which is then scraped to a crude phenol tank by a scraper. In the carbon dioxide flotation tank, carbon dioxide combines with sodium ions to form sodium bicarbonate. Phenolic organic matter has low solubility in sodium bicarbonate solution, so it floats to the surface of the liquid during the flotation process, further removing phenolic organic matter from the wastewater.

[0061] Step 4: Anaerobic reaction

[0062] The wastewater after carbon dioxide flotation in step 3 is fed into an anaerobic reactor. Nutrients are added to the anaerobic reactor, and the wastewater temperature and pH are controlled at 40°C and 8, respectively. The wastewater undergoes an anaerobic reaction, and the biogas produced is introduced into a biogas treatment system. The specific process includes: the anaerobic reactor includes an inlet tank, an anaerobic tank, and an anaerobic sedimentation tank. The inlet tank is equipped with a stirrer, a nutrient salt addition port, a pH adjustment port, and a steam heater. The wastewater after carbon dioxide flotation treatment flows in by gravity from the top of the inlet tank. Nutrients are added to the inlet tank, and the water temperature and pH are controlled at 40°C and 8, respectively. The wastewater is discharged from the bottom of the inlet tank and pumped into the anaerobic tank. The anaerobic reaction takes place in the anaerobic tank, and the biogas produced is introduced into the biogas treatment system. The wastewater flows by gravity from the lower part of the anaerobic tank into the anaerobic sedimentation tank. After sedimentation, solid-liquid separation occurs, and the wastewater is discharged from the effluent weir at the top of the anaerobic sedimentation tank.

[0063] Step 5: Precipitation

[0064] The wastewater after the anaerobic reaction in step 4 is fed into an anaerobic sedimentation tank, where it settles and is then discharged.

[0065] Comparative Example 1 used existing phenol-containing wastewater treatment methods. The wastewater was homogenized in an equalization tank, and the pH was adjusted before entering a cyanide removal reactor. A cyanide removal agent was added within a suitable pH range to ensure the optimal pH for polymer formation and precipitation. After cyanide removal, the wastewater was hydrolyzed and acidified. The COD removal rates of the phenol-containing wastewater treated in Examples 1-3 and Comparative Example 1 were...

[0066] COD removal rate % Example 1 78 Example 2 83 Example 3 80 Comparative Example 1 43

[0067] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for treating phenol-containing wastewater, characterized in that: The processing method includes the following steps: Step 1: Homogenization Wastewater is fed into equalization tank (1) for homogenization treatment; Step 2: Cyanide Removal The wastewater homogenized in step 1 is fed into the cyanide removal reactor (2). Sodium hydroxide is added to the cyanide removal reactor (2) to adjust the wastewater to alkalinity. Then, cyanide removal agent is added. After the reaction, acid is added to adjust the pH value of the wastewater. After sedimentation, the wastewater is discharged. Step 3: Carbon dioxide flotation The wastewater after cyanide removal in step 2 is fed into the carbon dioxide flotation tank (3), where carbon dioxide is used as the flotation carrier to separate the water-insoluble organic matter in the wastewater and scrape it to the crude phenol tank through a scraper. Step 4: Anaerobic Reactor The wastewater after carbon dioxide flotation in step 3 is fed into the anaerobic reactor (4). Nutrients are added to the anaerobic reactor (4), and the wastewater temperature is controlled at 30-40℃ and the wastewater pH value is controlled at 7-8. The wastewater undergoes anaerobic reaction, and the biogas produced is introduced into the biogas treatment system. Step 5: Precipitation The wastewater after the anaerobic reaction in step 4 is fed into the anaerobic sedimentation tank (403), and the wastewater is discharged after sedimentation in the anaerobic sedimentation tank (403); The cyanide removal reactor (2) includes a first coagulation tank (201), a second coagulation tank (202), a third coagulation tank (203), and a cyanide removal sedimentation tank (204). Wastewater homogenized in the equalization tank (1) enters from the top of the first coagulation tank (201). Simultaneously, sodium hydroxide is added at the inlet to adjust the wastewater pH to 9.5-10. The wastewater flows out from the bottom of the first coagulation tank (201) and simultaneously flows by gravity into the second coagulation tank (202). 2) Add cyanide removal agent and react for 30-90 minutes to form a stable complex. The wastewater flows by gravity from the top of the second coagulation tank (202) to the third coagulation tank (203). At the same time, acid is added to the third coagulation tank (203) to adjust the pH to 8-9, so that the complex can be quickly precipitated to separate the cyanide in the wastewater. The wastewater flows by gravity from the middle of the third coagulation tank (203) to the cyanide removal sedimentation tank (204). After sedimentation, the wastewater is discharged from the effluent weir of the cyanide removal sedimentation tank (204). The anaerobic reactor (4) includes an inlet pool (401), an anaerobic tank (402), and an anaerobic sedimentation tank (403). Wastewater treated by carbon dioxide flotation flows into the inlet pool (401) by gravity from the top. Nutrients are added to the inlet pool (401), the water temperature is controlled at 35-40℃, and the pH is controlled at 7-8. The wastewater is discharged from the bottom of the inlet pool (401) and pumped into the anaerobic tank (402). Anaerobic reaction takes place in the anaerobic tank (402), and the biogas produced is introduced into the biogas treatment system from the top of the anaerobic tank (402). The wastewater flows into the anaerobic sedimentation tank (403) from the lower part of the anaerobic tank (402) by gravity. After sedimentation, solid-liquid separation occurs, and the wastewater is discharged from the effluent weir at the top of the anaerobic sedimentation tank (403). The upper openings of the equalization tank (1), the cyanide removal reactor (2), and the carbon dioxide flotation tank (3) are all equipped with sealing covers.

2. The method for treating phenol-containing wastewater according to claim 1, characterized in that: The regulating tank (1) is a concrete structure, a fiberglass structure or a steel structure, and the manhole of the regulating tank (1) is sealed.

3. The method for treating phenol-containing wastewater according to claim 1, characterized in that: The phenol-containing wastewater is discharged into the equalization tank (1) after preliminary ammonia stripping and phenol removal treatment.

4. The method for treating phenol-containing wastewater according to claim 1, characterized in that: The anaerobic reactor (4) is equipped with a total phenol sampling tube. The number of sampling tubes is 5. Sampling is taken through the sampling tubes at different positions to observe the degradation of phenol at different stages.

5. The method for treating phenol-containing wastewater according to claim 1, characterized in that: The wastewater after sedimentation in step 5 is introduced into a secondary A / O wastewater treatment process for further treatment.

6. The method for treating phenol-containing wastewater according to claim 1, characterized in that: The wastewater was allowed to settle for 30 minutes in the cyanide removal sedimentation tank (204).

7. The method for treating phenol-containing wastewater according to claim 1, characterized in that: Pumps are installed between the equalization tank (1), the cyanide removal reactor (2), and the carbon dioxide flotation tank (3), and a pump is installed between the inlet tank (401) and the anaerobic tank (402).

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