Phenol-ammonia wastewater pretreatment method and system

Abstract

The present invention belongs to the field of wastewater treatment, and specifically, relates to a phenol-ammonia wastewater pretreatment method and system. The present invention discloses a phenol-ammonia wastewater pretreatment method, comprising the following steps: S1. monitoring the COD value A of the phenol-ammonia wastewater in the regulating tank; S2. judging the relationship between the COD value A of the phenol-ammonia wastewater and the limit value B; S3.2. if the COD value A of the phenol-ammonia wastewater in step S2. is not higher than the limit value B, electrolysis treatment is performed on the phenol-ammonia wastewater; the limit value B is the maximum COD value of the phenol-ammonia wastewater that can be treated by electrolysis. The beneficial effect of the present invention is to provide a phenol-ammonia wastewater pretreatment method that uses a COD monitoring device to monitor whether the phenol-ammonia wastewater meets the treatment standard of the electrochemical detoxification device, and if not, the phenol-ammonia wastewater is passed into an emergency storage tank, and emergency caching is performed on wastewater with a large index exceeding the limit, thereby avoiding impact on the subsequent phenol-ammonia wastewater treatment system and providing troubleshooting time for the front-end coal chemical production system.

Description

Technical Field

[0001] The present invention belongs to the field of wastewater treatment, and in particular relates to a phenol-ammonia wastewater pretreatment method and system. Background Art

[0002] During the pyrolysis and gasification process of low-rank coal, organic matter, ammonia, and other substances are mixed in the pyrolysis gas. Excess phenol-ammonia wastewater is discharged after cooling through water leaching and oil-water-slag separation. High-concentration phenol-ammonia wastewater is typically recycled through oil removal, stripping to remove acidic gases and recover ammonia, and extraction to recover phenol. This initially reduces pollutant concentrations and facilitates subsequent treatment.

[0003] Phenol-ammonia wastewater after resource recovery primarily contains pollutants such as oil, phenols, and ammonia nitrogen. Pretreatment methods such as flotation, coagulation, and hydrolysis-acidification are generally used to remove most of the oil and improve the biodegradability of the wastewater. Subsequently, a combination of anaerobic, anoxic, and aerobic biochemical treatments is used to achieve low-cost pollutant removal. The biochemical effluent undergoes advanced treatment before meeting discharge standards or being recycled.

[0004] Due to fluctuations in control and equipment maintenance during production processes such as the oil-water-slag separation process, as well as unstable operations in complex resource recovery equipment, the quality of phenol-ammonia wastewater entering pretreatment fluctuates significantly. Fluctuating levels of oil and phenol in the wastewater cannot be effectively absorbed by the pretreatment process, adversely affecting the microorganisms in the treatment equipment. Oil blocks the exchange of biological metabolites, and phenols are toxic to microorganisms. System recovery after these shocks can take months. In actual operation, the frequency of these fluctuations is high, and the cumulative impact of multiple shocks can cause the system to remain in an abnormal state for years, resulting in poor treatment results and increased operating costs.

[0005] Chinese Patent (Application) Document (I) 202211719460.0 discloses a method for treating high-concentration phenol-ammonia wastewater from semi-coke, which includes oil removal and impurity removal: the semi-coke wastewater is sequentially subjected to gravity sedimentation oil separation, precision filtration dust removal, and microfiltration backwashing for oil removal, so that the petroleum content of the deoiled effluent is less than 300 mg / L; deacidification and deammonification: the deoiled effluent that has been deoiled and impurity removed is subjected to gas deacidification and deammonification to separate the deaminated waste liquid and ammonia; adsorption dephenolization: the deaminated waste liquid is subjected to resin adsorption dephenolization to obtain dilute phenol water, wherein the petroleum content in the dilute phenol water is less than 100 mg / L and the phenol content is less than 650 mg / L; reuse treatment: the dilute phenol water obtained after adsorption dephenolization is subjected to biochemical treatment and deep treatment to meet the standards and then reused.

[0006] However, in Chinese Patent (Application) Document (I) 202211719460.0, if the COD value in phenol-ammonia wastewater is too high, exceeding the upper limit that the actual treatment system can handle, the COD content in the wastewater in the biochemical treatment step may also be too high, causing a large number of microorganisms to die, leading to the collapse of the treatment system and resulting in poor final wastewater treatment effect. Therefore, it is necessary to find effective measures to enhance the impact resistance and detoxification ability of pretreatment and ensure the stability of the entire phenol-ammonia wastewater treatment system. Summary of the Invention

[0007] 1. Technical problems to be solved:

[0008] In the existing technology, the water quality of phenol-ammonia wastewater generated by coal chemical production systems fluctuates greatly. The concentration of phenol-ammonia wastewater with excessive concentration still exceeds the limit that the wastewater treatment system can withstand after being treated by the pretreatment system, causing the wastewater treatment system to easily collapse after being impacted by the excessively concentrated phenol-ammonia wastewater, and the recovery time is relatively long.

[0009] 2. Technical solution

[0010] In order to solve the above technical problems, in a first aspect, the present invention provides a phenol-ammonia wastewater pretreatment method, comprising the following steps:

[0011] S1. Monitor the COD value A of phenol-ammonia wastewater in the regulating tank;

[0012] S2. Determine the relationship between the COD value A and the limit value B of phenol-ammonia wastewater;

[0013] S3.1. If the COD value of the phenol-ammonia wastewater in step S2 is higher than the limit value A, the phenol-ammonia wastewater is passed into the emergency storage tank;

[0014] S3.2 If step S2. The COD value of the phenol-ammonia wastewater A is not higher than the limit B, the phenol-ammonia wastewater is electrolyzed;

[0015] The limit value B is the maximum COD value of phenol-ammonia wastewater that can be treated by electrolysis.

[0016] Furthermore, limit B is 5000 mg / L.

[0017] Based on practical experience, COD values ​​within 5000 mg / L indicate that the subsequent system after the existing phenol-ammonia wastewater pretreatment operates with good stability and economy. Therefore, 5000 mg / L is the recommended value for Limit B. Limit B can be adjusted based on the actual treatment capacity of the subsequent system after the phenol-ammonia wastewater pretreatment.

[0018] Furthermore, in step S3.2, the current density during the electrolysis treatment is J, and the current density J satisfies the following relationship:

[0019] If the COD value A of the phenol-ammonia wastewater is not higher than the preset threshold value C, the current density J is a fixed value J1;

[0020] If the COD value A of the phenol-ammonia wastewater is higher than the preset threshold value C, the current density J changes to a value J2;

[0021] Among them, the relationship between J2 and the COD value A of phenol-ammonia wastewater is:

[0022] J2=1.8×10 -2 (AC)+J1.

[0023] Furthermore, the preset threshold C is 3000 mg / L.

[0024] Based on engineering experience, the phenol concentration in phenol-ammonia wastewater with a COD value of less than 3000 mg / L is generally between 450 and 500 mg / L, indicating low phenol toxicity. Under these conditions, increasing the current can help improve the final effluent quality of the pretreatment system, but the impact is minimal. To simplify control logic, a fixed low current (i.e., J1) is set for the electrochemical device below the preset threshold C. Based on this, 3000 mg / L is the recommended value for the preset threshold C.

[0025] Furthermore, the current density J ranges from 5 to 46 mA / cm 2 .

[0026] Furthermore, the current density J1 ranges from 5 to 10 mA / cm 2 .

[0027] Furthermore, during the electrolysis treatment in step S3.2, the pH value ranges from 3 to 10.

[0028] Furthermore, during the electrolysis treatment in step S3.2, the electrolyte concentration is 0.008 to 0.012 mol / L.

[0029] Furthermore, during the electrolysis treatment in step S3.2, the electrolyte concentration is 0.01 mol / L.

[0030] Furthermore, during the electrolysis treatment in step S3.2, the electrolysis time is 80 to 120 minutes.

[0031] Furthermore, during the electrolysis treatment in step S3.2, the electrolysis time is 100 minutes.

[0032] Furthermore, the electrolyte is one or more of sodium sulfate and potassium sulfate.

[0033] Furthermore, the electrolysis treatment process in step S3.2 is carried out under a protective gas atmosphere.

[0034] Furthermore, the protective gas is nitrogen or helium.

[0035] Furthermore, the protective gas is nitrogen.

[0036] Further, the phenol ammonia wastewater pretreatment method also includes the following steps:

[0037] S4. Hydrolyze and acidify the effluent treated in step S3.2.

[0038] Furthermore, in step S4., phenol-resistant microorganisms are subjected to targeted screening, proliferation and storage.

[0039] Furthermore, the environmental conditions for the targeted screening and proliferation of phenol-resistant microorganisms are:

[0040] The pH value is 6-7, the temperature is 25-35°C, and the phenol concentration is 100-300 mg / L.

[0041] In a second aspect, the present invention provides a phenol-ammonia wastewater pretreatment system used in the aforementioned phenol-ammonia wastewater pretreatment method, comprising:

[0042] Equalization tank, used to accommodate phenol-ammonia wastewater;

[0043] The emergency storage tank is connected to the regulating tank. When the COD value A of the phenol-ammonia wastewater is higher than the limit value B, it is used to receive and temporarily store the phenol-ammonia wastewater in the regulating tank;

[0044] The electrochemical detoxification device is connected to the regulating tank and is used to receive the phenol-ammonia wastewater in the regulating tank and perform electrolytic treatment when the COD value A of the phenol-ammonia wastewater is not higher than the limit value B;

[0045] COD monitoring device, used to monitor the COD value A of phenol-ammonia wastewater in the regulating tank;

[0046] A control computer is electrically connected to the COD monitoring device to receive an electrical signal transmitted by the COD monitoring device;

[0047] A hydrolysis and acidification device, connected to the electrochemical detoxification device, for hydrolyzing and acidifying the water body after electrolysis treatment;

[0048] Limit B is the maximum COD value of phenol-ammonia wastewater that can be treated by the electrochemical detoxification device.

[0049] Furthermore, the capacity of the emergency storage tank meets the requirement that the hydraulic retention time of the phenol-ammonia wastewater is not less than 24 hours.

[0050] Furthermore, the phenol-ammonia wastewater pretreatment system also includes a pH value monitoring device for monitoring the pH value of the phenol-ammonia wastewater in the regulating tank.

[0051] Furthermore, the phenol-ammonia wastewater pretreatment system also includes a temperature monitoring device for monitoring the temperature of the phenol-ammonia wastewater in the regulating tank.

[0052] Furthermore, the electrochemical detoxification device includes a power supply; a control computer is electrically connected to the power supply to control the current density J according to the COD value A of the phenol-ammonia wastewater.

[0053] Furthermore, the current density J of the power supply can be adjusted.

[0054] Furthermore, the electrochemical detoxification device also includes a protective gas source for providing protective gas for the electrolytic treatment process in step S3.2.

[0055] Furthermore, the electrochemical detoxification device also includes a reagent dosing module for adding an oxidant to the phenol-ammonia wastewater.

[0056] Furthermore, the electrochemical detoxification device also includes an electrochemical device.

[0057] For example, an electrochemical device is an electrolyzer.

[0058] Furthermore, the hydrolysis acidification device is of full mixing type, upflow type or baffled type.

[0059] Furthermore, the phenol-ammonia wastewater pretreatment system also includes a biological expansion device connected to the hydrolysis and acidification device for targeted screening, proliferation and storage of phenol-resistant microorganisms.

[0060] Furthermore, the phenol-ammonia wastewater pretreatment system also includes a nutrient adding device connected to the hydrolysis and acidification device for adding nutrients to the hydrolysis and acidification device.

[0061] Furthermore, the nutrients include one or more of organic carbon, nitrogen, phosphorus, and trace elements.

[0062] 3. Beneficial effects

[0063] The beneficial effects of the present invention are: providing a phenol-ammonia wastewater pretreatment method which utilizes a COD monitoring device to monitor whether phenol-ammonia wastewater meets the treatment standards of an electrochemical detoxification device, and if not, passes the phenol-ammonia wastewater into an emergency storage tank, thereby performing emergency caching on wastewater that significantly exceeds the limit index, thereby avoiding impact on subsequent phenol-ammonia wastewater treatment systems and providing troubleshooting time for the front-end coal chemical production system.

[0064] The present invention provides a pretreatment method for a graded treatment of phenol-ammonia wastewater. After determining that the phenol-ammonia wastewater meets the treatment standard of an electrochemical detoxification device, the current density in the electrochemical detoxification device is adjusted according to the COD value of the phenol-ammonia wastewater monitored by a COD monitoring device to balance small fluctuations in the inlet water index, thereby making the outlet water quality more stable.

[0065] The electrochemical detoxification device of the present invention matches the operating treatment parameters according to the water quality indicators of the phenol-ammonia wastewater monitored by the COD monitoring device, reduces the concentration of phenol-ammonia in the water, and ensures that the toxicity of the wastewater entering the hydrolysis and acidification device is controllable.

[0066] The biological expansion device in the present invention selectively screens and proliferates phenol-resistant microorganisms, provides rapid replenishment and enhanced microbial reserves when the system encounters fluctuations and shocks, enhances the flexibility and shock resistance of the phenol-ammonia wastewater pretreatment system, and improves the toxicity resistance and rapid recovery capabilities of the phenol-ammonia wastewater pretreatment system. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The accompanying drawings, which constitute part of the present invention, are used to provide a further understanding of the present invention and make other features, objects and advantages of the present invention more apparent. The accompanying drawings and descriptions of the exemplary embodiments of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0068] In the attached figure:

[0069] Figure 1 This is a schematic diagram of the device connection relationship of a phenol-ammonia wastewater pretreatment system according to an embodiment of the present invention, mainly showing structures such as a regulating tank and an emergency storage tank;

[0070] Figure 2 yes Figure 1 A schematic structural diagram of the electrochemical detoxification device in the illustrated embodiment;

[0071] Figure 3 This is a schematic structural diagram of the electrical control portion of a phenol-ammonia wastewater pretreatment system according to an embodiment of the present invention, mainly showing structures such as a COD monitoring device and a control computer.

[0072] Meaning of reference numerals

[0073] 100. Phenol-ammonia wastewater pretreatment system; 101. Equalization tank; 102. Emergency storage tank; 103. Electrochemical detoxification device; 103a. Power supply; 103b. Protective gas source; 103c. Chemical dosing module; 103d. Electrochemical device; 104. COD monitoring device; 105. Control computer; 106. Hydrolysis and acidification device; 107. pH monitoring device; 108. Temperature monitoring device; 109. Biological expansion device; 110. Nutrient dosing device. DETAILED DESCRIPTION

[0074] The following are embodiments of the present disclosure. It should be understood that the present disclosure can be implemented in various forms and should not be construed as being limited to the embodiments set forth herein. On the contrary, the embodiments and examples are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the embodiments of the present disclosure are intended to be illustrative only and are not intended to limit the scope of protection of the present disclosure.

[0075] It should be noted that the modifications of "one" and "multiple" mentioned in the present disclosure are illustrative rather than restrictive, and those skilled in the art should understand that unless otherwise clearly indicated in the context, they should be understood as "one or more".

[0076] In order to solve the above technical problems, the present invention provides a method for pretreating phenol-ammonia wastewater, comprising the following steps:

[0077] S1 monitoring the COD value of phenol-ammonia wastewater in the regulating tank 101 A;

[0078] S2. Determine the relationship between the COD value A and the limit value B of phenol-ammonia wastewater;

[0079] S3.1. If the COD value of the phenol-ammonia wastewater in step S2 is higher than the limit value A B, the phenol-ammonia wastewater is passed into the emergency storage tank 102;

[0080] S3.2 If step S2. The COD value of the phenol-ammonia wastewater A is not higher than the limit B, the phenol-ammonia wastewater is electrolyzed;

[0081] The limit value B is the maximum COD value of phenol-ammonia wastewater that can be treated by electrolysis.

[0082] By adopting the above technical solution, the COD monitoring device 104 is used to monitor whether the phenol-ammonia wastewater meets the treatment standards of the electrochemical detoxification device 103. If not, the phenol-ammonia wastewater is passed into the emergency storage tank 102 to perform emergency caching on wastewater that significantly exceeds the limit indicators to avoid impact on subsequent systems and provide troubleshooting time for the front-end coal chemical production system.

[0083] The COD value A of the phenol-ammonia wastewater in the equalization tank 101 is higher than the limit value B, which means that there is a possibility of abnormality in the system or process of a certain production link in actual production. The time period during which the phenol-ammonia wastewater is temporarily stored in the emergency storage tank 102 can provide time for professionals to check the production line and production system and eliminate related faults.

[0084] Furthermore, limit B is 5000 mg / L.

[0085] Furthermore, in step S3.2, the current density during the electrolysis treatment is J, and the current density J satisfies the following relationship:

[0086] If the COD value A of the phenol-ammonia wastewater is not higher than the preset threshold value C, the current density J is a fixed value J1;

[0087] If the COD value A of the phenol-ammonia wastewater is higher than the preset threshold value C, the current density J changes to a value J2;

[0088] Among them, the relationship between J2 and the COD value A of phenol-ammonia wastewater is:

[0089] J2=1.8×10 -2 (AC)+J1.

[0090] Furthermore, the preset threshold C is 3000 mg / L.

[0091] When the COD value A in the phenol-ammonia wastewater is below the preset threshold value C, the current density is J1, which can effectively electrochemically treat the organic matter in the phenol-ammonia wastewater. However, when the COD value A exceeds the preset threshold value C, the current density needs to be increased accordingly to effectively treat the phenol-ammonia wastewater.

[0092] Furthermore, the current density J ranges from 5 to 46 mA / cm 2 .

[0093] Furthermore, the current density J1 ranges from 5 to 10 mA / cm 2 .

[0094] Furthermore, during the electrolysis treatment in step S3.2, the pH value ranges from 3 to 10.

[0095] Furthermore, during the electrolysis treatment in step S3.2, the electrolyte concentration is 0.008 to 0.012 mol / L.

[0096] Furthermore, during the electrolysis treatment in step S3.2, the electrolyte concentration is 0.01 mol / L.

[0097] Furthermore, during the electrolysis treatment in step S3.2, the electrolysis time is 80 to 120 minutes.

[0098] Furthermore, during the electrolysis treatment in step S3.2, the electrolysis time is 100 minutes.

[0099] Furthermore, the electrolyte is one or more of sodium sulfate and potassium sulfate.

[0100] Furthermore, the electrolysis treatment process in step S3.2 is carried out under a protective gas atmosphere.

[0101] Furthermore, the protective gas is nitrogen or helium.

[0102] Furthermore, the protective gas is nitrogen.

[0103] The electrochemical detoxification device 103 can remove residual oils in the phenol-ammonia wastewater, destroy the molecular structure of toxic substances, reduce the concentration of oils and poisons, and further reduce the COD concentration, thereby improving the biodegradability of the phenol-ammonia wastewater in subsequent biochemical treatment.

[0104] Further, the phenol ammonia wastewater pretreatment method also includes the following steps:

[0105] S4. Hydrolyze and acidify the effluent treated in step S3.2.

[0106] Furthermore, in step S4., phenol-resistant microorganisms are subjected to targeted screening, proliferation and storage.

[0107] Furthermore, the environmental conditions for the targeted screening and proliferation of phenol-resistant microorganisms are:

[0108] The pH value is 6-7, the temperature is 25-35°C, and the phenol concentration is 100-300 mg / L.

[0109] Hydrolysis and acidification can further reduce the concentration of phenols and ammonia in the water. Furthermore, by enriching and multiplying microorganisms that can adapt to toxic substances (primarily phenols and ammonia) in the wastewater, when the effluent index of the electrolytic detoxification system increases, the microorganisms can be quickly replenished, increasing the biomass concentration and ensuring that the index fluctuation of the effluent of phenols and ammonia is relatively gentle, which is beneficial for subsequent treatment.

[0110] In traditional phenol-ammonia wastewater pretreatment system 100, due to the excessively high phenol-ammonia content in the wastewater and the lack of monitoring devices, the phenol-ammonia wastewater with excessively high concentrations can cause a large number of microorganisms to die in the hydrolysis and acidification step. If the microbial flora is waiting to recover on its own, it will take several months or even half a year, which will have a serious impact on the treatment efficiency of the phenol-ammonia wastewater. Moreover, due to a malfunction of the electrochemical detoxification device 103, the treatment effect of the phenol-ammonia wastewater is significantly reduced. The phenol-ammonia wastewater processed by the electrochemical detoxification device 103 enters the hydrolysis and acidification step, which also has a significant adverse effect on the survival of microorganisms due to the excessively high phenol-ammonia concentration. Waiting for the flora to recover also requires a considerable period of time. However, the present invention carries out directional screening, proliferation and storage of phenol-resistant microorganisms, can reduce the risk of the above-mentioned problems, and improves the treatment efficiency of the pretreatment system.

[0111] In a second aspect, the present invention provides a phenol-ammonia wastewater pretreatment system 100 used in the aforementioned phenol-ammonia wastewater pretreatment method, comprising:

[0112] The regulating tank 101 is used to accommodate phenol-ammonia wastewater;

[0113] The emergency storage tank 102 is connected to the regulating tank 101 and is used to receive and temporarily store the phenol-ammonia wastewater in the regulating tank 101 when the COD value A of the phenol-ammonia wastewater is higher than the limit value B;

[0114] The electrochemical detoxification device 103 is connected to the regulating tank 101 and is used to receive the phenol-ammonia wastewater in the regulating tank 101 and perform electrolytic treatment when the COD value A of the phenol-ammonia wastewater is not higher than the limit value B;

[0115] A COD monitoring device 104 is used to monitor the COD value A of the phenol-ammonia wastewater in the regulating tank 101;

[0116] The control computer 105 is electrically connected to the COD monitoring device 104 to receive the electrical signal transmitted by the COD monitoring device 104;

[0117] The hydrolysis and acidification device 106 is connected to the electrochemical detoxification device 103 and is used to hydrolyze and acidify the water after the electrolysis treatment;

[0118] Limit value B is the maximum COD value of phenol-ammonia wastewater that can be treated by the electrochemical detoxification device 103.

[0119] The regulating tank 101 in the present invention is not only used to accommodate wastewater, but also plays a preliminary homogenizing role to overcome the heterogeneity of the phenol-ammonia wastewater as much as possible and improve the dispersion of pollutants therein. For example, the homogenizing method can be stirring.

[0120] Furthermore, the capacity of the emergency storage tank 102 satisfies the requirement that the hydraulic retention time of the phenol-ammonia wastewater is not less than 24 hours.

[0121] Furthermore, the phenol-ammonia wastewater pretreatment system 100 further includes a pH value monitoring device 107 for monitoring the pH value of the phenol-ammonia wastewater in the regulating tank 101 .

[0122] Furthermore, the phenol-ammonia wastewater pretreatment system 100 further includes a temperature monitoring device 108 for monitoring the temperature of the phenol-ammonia wastewater in the regulating tank 101 .

[0123] Furthermore, the COD monitoring device 104, the pH value monitoring device 107 and the temperature monitoring device 108 may be independent monitoring devices or monitoring devices capable of simultaneously monitoring multiple indicators including but not limited to COD, pH value and temperature.

[0124] Furthermore, the electrochemical detoxification device 103 includes a power supply 103a; and a control computer 105 is electrically connected to the power supply 103a to control the current density J according to the COD value A of the phenol-ammonia wastewater.

[0125] Furthermore, the current density J of the power source 103 a is adjustable.

[0126] Furthermore, the electrochemical detoxification device 103 further includes a protective gas source 103b for providing protective gas for the electrolytic treatment process in step S3.2.

[0127] Furthermore, the electrochemical detoxification device 103 also includes a reagent dosing module 103c for adding an oxidant to the phenol-ammonia wastewater.

[0128] Furthermore, the electrochemical detoxification device 103 further includes an electrochemical device 103d.

[0129] For example, the electrochemical device 103d is an electrolytic cell.

[0130] Furthermore, the hydrolysis acidification device 106 is of full mixing type, upflow type or baffled type.

[0131] Furthermore, the phenol-ammonia wastewater pretreatment system 100 also includes a biological expansion device 109 connected to the hydrolysis and acidification device 106 for targeted screening, proliferation and storage of phenol-resistant microorganisms.

[0132] Furthermore, the phenol-ammonia wastewater pretreatment system 100 further includes a nutrient dosing device 110 connected to the hydrolysis-acidification device 106 for adding nutrients to the hydrolysis-acidification device 106 .

[0133] Furthermore, the nutrients include one or more of organic carbon, nitrogen, phosphorus, and trace elements. Specific embodiments

[0135] Example 1

[0136] This specific embodiment provides a phenol-ammonia wastewater pretreatment system 100, comprising: a regulating tank 101 for accommodating phenol-ammonia wastewater; an emergency storage tank 102, connected to the regulating tank 101, for receiving and temporarily storing the phenol-ammonia wastewater in the regulating tank 101 when the COD value A of the phenol-ammonia wastewater is higher than the limit value B; an electrochemical detoxification device 103, connected to the regulating tank 101, for receiving the phenol-ammonia wastewater in the regulating tank 101 and performing electrolytic treatment when the COD value A of the phenol-ammonia wastewater is not higher than the limit value B; a COD monitoring device 104, for monitoring the COD value A of the phenol-ammonia wastewater in the regulating tank 101; a control computer 105, electrically connected to the COD monitoring device 104 to receive the electrical signal transmitted by the COD monitoring device 104; and a hydrolysis and acidification device 106, connected to the water outlet of the electrochemical detoxification device 103, for hydrolyzing and acidifying the water body after electrolysis treatment.

[0137] The capacity of the emergency storage tank 102 in the present embodiment is 840 cubic meters, and it is 24 hours to meet the hydraulic retention time of phenol-ammonia wastewater.Phenol-ammonia wastewater pretreatment system 100 also comprises pH value monitoring device 107 and temperature monitoring device 108.Specifically, the COD monitoring device 104, pH value monitoring device 107 and temperature monitoring device 108 that the present embodiment uses are COD online automatic monitoring instrument, band remote transmission glass electrode pH meter, band remote transmission thermocouple thermometer, and using method are installed in the position of mixing in the regulating tank 101.Aforesaid COD online automatic monitoring instrument, band remote transmission glass electrode pH meter, band remote transmission thermocouple thermometer use common online monitoring instrument on the market and get final product, do not go into details at this.

[0138] The electrochemical detoxification device 103 in this embodiment includes a power supply 103a; a control computer 105 is electrically connected to the power supply 103a to control the current density J according to the COD value A of the phenol-ammonia wastewater.

[0139] The current density J of the power supply 103a is adjustable. In this embodiment, the current density J is adjusted by controlling the voltage of the power supply 103a. The electrochemical detoxification device 103 further includes a protective gas source 103b, a reagent dosing module 103c, and an electrochemical device 103d. The protective gas source 103b provides nitrogen; the reagent dosing module 103c adds hydrogen peroxide, an oxidant, to the phenol-ammonia wastewater in the regulating tank 101 when the COD value A reaches the limit value B, to improve the degradation capacity of phenols in the phenol-ammonia wastewater in an emergency.

[0140] The purpose of adding hydrogen peroxide is: if the volume of phenol-ammonia wastewater with COD higher than the limit value B is greater than the capacity of the emergency storage tank 102, this part of the phenol-ammonia wastewater that should not enter the electrochemical detoxification device 103 enters the electrochemical detoxification device 103. In this case, the reagent dosing module 103c adds the oxidant hydrogen peroxide to the phenol-ammonia wastewater to quickly reduce the COD value.

[0141] The reagent dosing module 103c is a temporary backup measure, manually controlled, and the dosage is determined by individual tests based on the actual COD value of the phenol-ammonia wastewater. The electrochemical device 103d is an electrolytic cell. In this embodiment, the electrolytic cell has a titanium anode and a graphite cathode.

[0142] The hydrolysis and acidification device 106 in the present embodiment is a fully mixed type. The phenol-ammonia wastewater pretreatment system 100 also includes a biological expansion device 109, which is connected to the hydrolysis and acidification device 106 and is used for directional screening, proliferation and storage of phenol-resistant microorganisms. The phenol-ammonia wastewater pretreatment system 100 also includes a nutrient dosing device 110, which is connected to the hydrolysis and acidification device 106 and is used for adding nutrients to the hydrolysis and acidification device 106. The nutrients include organic carbon, nitrogen, phosphorus, and trace elements.

[0143] Example 2

[0144] In this specific embodiment, the limit value B is set to 5000 mg / L and the preset threshold value C is set to 3000 mg / L. Phenol-ammonia wastewater is introduced into the regulating tank 101. The COD value A of the phenol-ammonia wastewater in the regulating tank 101 is monitored to be 2800 mg / L, which is lower than the limit value B. The phenol-ammonia wastewater is introduced into the electrochemical detoxification device 103 for electrolysis treatment. Since the COD value A of the phenol-ammonia wastewater is not higher than the preset threshold value C, the current density J is fixed at J1; J1 is 6 mA / cm 2 .

[0145] During the electrolytic treatment process, the pH value fluctuates between 6 and 8. The pH value is determined by the front-end coal chemical production system and is acceptable within this range. Abnormal pH values ​​are rare and require immediate production halt and repair. Once the pH value is restored, production can resume.

[0146] The electrolyte concentration is 0.01 mol / L. The electrolyte in this embodiment is sodium sulfate. The electrolysis time is 100 min. The protective gas provided by protective gas source 103b is nitrogen.

[0147] After electrolysis treatment in electrochemical detoxification unit 103, the phenol-ammonia wastewater is passed to hydrolysis and acidification unit 106 for hydrolysis and acidification. In this embodiment, hydrolysis and acidification unit 106 is an upflow unit. Sludge with good settling properties from hydrolysis and acidification unit 106 is introduced into bio-expansion unit 109, where phenol-resistant microorganisms are targeted for screening, proliferation, and storage. The environmental conditions for targeted screening and proliferation of phenol-resistant microorganisms are: a pH of approximately 6.5, a temperature of approximately 35°C, and a phenol concentration of approximately 300 mg / L.

[0148] The phenol concentration of the phenol-ammonia wastewater treated by the phenol-ammonia wastewater pretreatment method and the phenol-ammonia wastewater pretreatment system 100 of this embodiment is controlled within 50 mg / L.

[0149] Example 3

[0150] In this specific embodiment, limit value B is set to 5000mg / L, and preset threshold value C is set to 3000mg / L. In regulating tank 101, phenol-ammonia waste water is fed. When the COD value A of the phenol-ammonia waste water monitored in regulating tank 101 is 4000mg / L and lower than limit value B, the phenol-ammonia waste water is fed into electrochemical detoxification device 103 and electrolytic treatment is carried out. Because the COD value A of the phenol-ammonia waste water is 4000mg / L and higher than preset threshold value C, the current density J is a variable value J2.

[0151] The relationship between J2 and the COD value A of the phenol-ammonia wastewater is: J2 = 1.8 × 10-2 (AC) + J1. In this embodiment, J1 is 10 mA / cm 2 , J2 is 28mA / cm 2 The J2 value is adjusted in real time by the computer program of the control computer 105 according to the COD monitoring value. The COD value A of 4000 mg / L is a temporary value at a certain moment in the treatment process, but the J2 value is not higher than 46 mA / cm 2 .

[0152] During the electrolysis treatment, the pH value fluctuates within the range of 7 to 7.5.

[0153] The electrolyte concentration is 0.01 mol / L. The electrolyte in this embodiment is sodium sulfate. The electrolysis time is 100 min. The protective gas provided by protective gas source 103b is nitrogen.

[0154] After electrolysis treatment in electrochemical detoxification unit 103, the phenol-ammonia wastewater is passed to hydrolysis and acidification unit 106 for hydrolysis and acidification. In this embodiment, hydrolysis and acidification unit 106 is a baffled flow unit. Sludge with good settling properties from hydrolysis and acidification unit 106 is introduced into bio-expansion unit 109, where phenol-resistant microorganisms are targeted for screening, proliferation, and storage. The environmental conditions for targeted screening and proliferation of phenol-resistant microorganisms are: a pH of approximately 7, a temperature of approximately 30°C, and a phenol concentration of 280 mg / L.

[0155] The phenol concentration of the phenol-ammonia wastewater treated by the phenol-ammonia wastewater pretreatment method and the phenol-ammonia wastewater pretreatment system 100 of this embodiment is controlled within 50 mg / L.

[0156] Example 4

[0157] In this specific embodiment, the limit value B is set to 5000 mg / L, and the preset threshold value C is set to 3000 mg / L. Phenol-ammonia wastewater is introduced into the regulating tank 101. When the COD monitoring device 104 detects that the COD value A of the phenol-ammonia wastewater in the regulating tank 101 is higher than the limit value B, the phenol-ammonia wastewater is introduced into the emergency storage tank 102. Professional personnel then conduct an inspection of the front-end coal chemical production system and eliminate related faults.

[0158] Comparative Example 1

[0159] In this comparative example, phenol-ammonia wastewater generated by the coal chemical industry was treated by conventional flotation, coagulation, hydrolysis and acidification pretreatment methods.

[0160] In the phenol-ammonia wastewater treated by the above-mentioned traditional pretreatment system, the COD concentration fluctuates greatly, exceeding the treatment capacity of the secondary treatment system (the treatment system after the pretreatment system), causing the secondary treatment system to collapse and the COD in the treated phenol-ammonia wastewater not meeting the requirements.

[0161] Comparative Example 2

[0162] This comparative example is basically the same as Example 3. Phenol-ammonia wastewater is introduced into the regulating tank 101. It is monitored that the COD value A (4000 mg / L) of the phenol-ammonia wastewater in the regulating tank 101 is lower than the limit value B. The phenol-ammonia wastewater is introduced into the electrochemical detoxification device 103 for electrolytic treatment.

[0163] The difference between this comparative example and Example 3 is that, although the COD value A of the phenol-ammonia wastewater is higher than the preset threshold value C, the current density J during the electrolysis treatment in this comparative example is a fixed value J1 (10 mA / cm2 ).

[0164] The rest is the same as Example 3.

[0165] The phenol concentration of the phenol-ammonia wastewater treated by the phenol-ammonia wastewater pretreatment method and the phenol-ammonia wastewater pretreatment system 100 of this comparative example is 800 mg / L, which exceeds the limit that the secondary treatment system can withstand.

[0166] The present invention has been described in detail above with reference to specific exemplary embodiments. However, it should be understood that various modifications and variations may be made without departing from the scope of the present invention as defined by the appended claims. The detailed description and accompanying drawings should be considered merely illustrative and not restrictive, and any such modifications and variations, if any, are intended to fall within the scope of the present invention as described herein. In addition, the background technology is intended to illustrate the current status and significance of the present technology and is not intended to limit the present invention or its application areas.

[0167] More specifically, although exemplary embodiments of the present invention have been described herein, the present invention is not limited to these embodiments, but rather includes any and all embodiments that may be recognized by those skilled in the art based on the foregoing detailed description, such as combinations between the various embodiments, adaptations, and / or substitutions. The limitations in the claims are to be interpreted broadly based on the language used in the claims and are not limited to the examples described in the foregoing detailed description or during the prosecution of this application, which examples should be considered non-exclusive. Any steps recited in any method or process claim may be performed in any order and are not limited to the order set forth in the claims. Therefore, the scope of the invention should be determined solely by the appended claims and their legal equivalents, rather than by the description and examples given above.

Claims

1. A phenol-ammonia wastewater pretreatment method, characterized in that, The following steps are involved: S1. Monitor the COD value A of phenol-ammonia wastewater in the regulating tank; S2. Determine the relationship between the COD value A and the limit value B of the phenol-ammonia wastewater; the limit value B is the maximum COD value of the phenol-ammonia wastewater that can be treated by electrolysis; the limit value B is 5000 mg / L; S3.2 If step S2. The COD value of the phenol-ammonia wastewater A is not higher than the limit B, the phenol-ammonia wastewater is electrolyzed; In step S3.2, the current density during the electrolysis treatment is J, and the current density J satisfies the following relationship: If the COD value A of the phenol-ammonia wastewater is not higher than the preset threshold value C, the current density J is a fixed value J1; If the COD value A of the phenol-ammonia wastewater is higher than the preset threshold value C, the current density J is changed to a value J2; Wherein, the relationship between the J2 and the COD value A of the phenol-ammonia wastewater is: J2=1.8×10 -2 (A-C)+J1; The preset threshold C is 3000 mg / L.

2. phenol ammonia wastewater pretreatment method according to claim 1, is characterized in that, The current density J1 ranges from 5 to 10 mA / cm 2 .

3. phenol ammonia wastewater pretreatment method according to claim 1, is characterized in that, During the electrolysis treatment in step S3.2, the pH value ranges from 3 to 10; and the electrolyte concentration ranges from 0.008 to 0.012 mol / L.

4. phenol ammonia wastewater pretreatment method according to claim 1, is characterized in that, The electrolysis treatment process in step S3.2 is carried out under a protective gas atmosphere.

5. phenol ammonia wastewater pretreatment method according to claim 1, is characterized in that, The following steps are also included: S4. Hydrolyze and acidify the effluent treated in step S3.

2.

6. phenol ammonia wastewater pretreatment method according to claim 5, is characterized in that, In the step S4., phenol-resistant microorganisms are subjected to targeted screening, proliferation and storage.

7. The phenol-ammonia wastewater pretreatment method according to claim 6, wherein The conditions for the targeted screening and proliferation of phenol-resistant microorganisms are: The pH value is 6~7, the temperature is 25~35℃, and the phenol concentration is 100~300mg / L.

8. The phenol ammonia wastewater pretreatment system according to any one of claims 1 to 7, wherein: include: Equalization tank, used to accommodate phenol-ammonia wastewater; An emergency storage tank is connected to the regulating tank and is used to receive and temporarily store the phenol-ammonia wastewater in the regulating tank when the COD value A of the phenol-ammonia wastewater is higher than the limit value B; An electrochemical detoxification device is connected to the regulating tank and is used to receive the phenol-ammonia wastewater in the regulating tank and perform electrolytic treatment when the COD value A of the phenol-ammonia wastewater is not higher than the limit value B; COD monitoring device, used to monitor the COD value A of phenol-ammonia wastewater in the regulating tank; a control computer, electrically connected to the COD monitoring device to receive the electrical signal transmitted by the COD monitoring device; A hydrolysis and acidification device, connected to the electrochemical detoxification device, for hydrolyzing and acidifying the water body after electrolysis treatment; The limit value B is the maximum COD value of phenol-ammonia wastewater that can be treated by the electrochemical detoxification device.

9. The phenol-ammonia wastewater pretreatment system according to claim 8, wherein The electrochemical detoxification device comprises a power source; The control computer is electrically connected to the power supply to control the current density J according to the COD value A of the phenol-ammonia wastewater.

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