Microbe-loaded activated carbon composition, process and apparatus for pretreating wastewater containing nitrile

Abstract

The application discloses a microorganism-loaded activated carbon composition, a nitrile-containing wastewater pretreatment process and device and the device, and belongs to the technical field of microorganism culture and wastewater treatment device. In view of the technical problems that the electric conduction capacity and biodegradation efficiency of biological filler are poor when an electric catalysis internal circulation aeration biological filter is used for pretreatment of nitrile-containing wastewater in the prior art, and only the biodegradability of wastewater is improved, and the organic nitrile cannot be converted into available substrate, the application provides a microorganism-loaded activated carbon composition, which comprises activated carbon loaded with Shewanella oneidensis or Rhodococcus globerulus at a mass ratio of 1:2 to 1:3, and the amount of the activated carbon loaded with Shewanella oneidensis or Rhodococcus globerulus is 10 9 ~ 10 10 CFU / g, and the composition has good electric conduction capacity and biodegradation efficiency. The application further provides a nitrile-containing wastewater pretreatment process and device, which comprises the following steps: introducing nitrile-containing wastewater into the device body, and sequentially using electric treatment and a micro-nano bubble generator for treatment, and has the advantages of low power consumption, low treatment cost, convenient and safe operation, green and environment-friendly process and the like.

Description

Technical Field

[0001] This invention belongs to the technical field of wastewater treatment devices, and more specifically, relates to an activated carbon composition loaded with microorganisms, a pretreatment process for nitrile wastewater, and a device. Background Technology

[0002] Acrylonitrile-containing chemical wastewater refers to wastewater generated during chemical production processes, especially during the production of acrylonitrile or other organic nitrile compounds. This type of wastewater contains a large amount of organic nitrile compounds, such as acrylonitrile, acetonitrile, and acrylonitrile oligomers. The treatment of nitrile-containing chemical wastewater faces several challenges: (1) Bioinhibition and toxicity: Organic nitrile compounds have a strong inhibitory effect on microorganisms. Even low concentrations of nitrile compounds can significantly affect the activity of microorganisms, which limits the application of biological treatment technologies. (2) High content of recalcitrant organic matter: The organic matter in nitrile-containing wastewater often has a complex structure and is difficult to degrade by conventional biological treatment methods. Pretreatment is required to improve its biodegradability. (3) Low treatment efficiency: Traditional physical, chemical, and biological treatment methods often fail to effectively remove pollutants from nitrile-containing wastewater, resulting in low treatment efficiency. (4) Cost and operational complexity: Some efficient treatment technologies, such as membrane treatment technology, although having good treatment effects, have high operating costs and high energy consumption, which limits their widespread application in chemical plant wastewater treatment. (5) Limitations of anaerobic treatment: Anaerobic microorganisms are extremely sensitive to environmental conditions such as pH, temperature and toxicity. The treatment process may produce malodorous gases. Furthermore, anaerobic treatment systems have certain requirements for the biodegradability of wastewater, while the biodegradability of nitrile wastewater is often poor.

[0003] The main treatment methods for nitrile chemical wastewater include the following: (1) Chemical oxidation method: adding oxidants (such as hydrogen peroxide, ozone, liquid chlorine, etc.) to oxidize and decompose organic nitrile compounds in wastewater. The disadvantage is that the cost is high and a large amount of chemical sludge may be generated. (2) Physical treatment method: including filtration, gravity sedimentation and air flotation. The process is simple and easy to manage, but it cannot effectively remove soluble wastewater components and has great limitations. (3) Electrochemical oxidation method: in the electrolytic cell, organic pollutants in wastewater undergo oxidation-reduction reactions on the electrodes and are removed. There are problems such as high energy consumption, high cost and side reactions. (4) Biological method: including SBR method, biological contact oxidation method, aerobic biochemical method, acidification pretreatment, biofiltration and addition of special bacteria. It can reduce the content of organic matter in wastewater and improve its biodegradability, but the degradation ability of organic nitrile is limited and the treatment efficiency may not be high. (5) Photocatalytic oxidation technology: using photo-excited oxidation to combine oxidants with light radiation, it can treat recalcitrant substances. There may be problems with high equipment costs and complex operation. (6) Adsorption method: such as activated carbon adsorption, resin adsorption, etc., can effectively remove organic matter in wastewater. The disadvantage is that the regeneration of the adsorbent is difficult and there may be problems with limited adsorption capacity. (7) Fenton oxidation method: high treatment efficiency, but requires the addition of a large amount of reagents, which is very costly and easily produces a large amount of chemical sludge. Moreover, many pollutants cannot be completely degraded, producing a large amount of intermediate products, and the effluent often cannot meet the requirements for reuse. (8) Electrocatalytic internal circulation aerated biological filter: combining three-dimensional electrode advanced oxidation technology and biofilm technology, it can effectively treat recalcitrant industrial wastewater. However, the equipment investment for this method may be high and the operation and maintenance are complicated.

[0004] Among the above methods, the electrocatalytic internal circulation aerated biological filter method has a relatively high pollutant removal efficiency and strong resistance to shock loads compared to other methods. Chinese invention application publication number CN113511719A, application date April 10, 2020, entitled "Electrocatalytic Internal Circulation Aerated Biological Filter and Wastewater Aeration Method," discloses an electrocatalytic internal circulation aerated biological filter comprising: a tank body, at least partially open at the top; a support structure dividing the tank body into an upper space and a lower space, allowing water to pass through; a catalyst layer disposed in the upper space; a biological packing layer stacked on top of the catalyst layer and disposed below the catalyst layer; a flow guide tube penetrating all layers and communicating with the lower space; an aeration unit disposed at the bottom of the flow guide tube; an inlet water unit disposed at the bottom of the tank body; and electrodes disposed within the catalyst layer. This scheme integrates three-dimensional electrode advanced oxidation technology with biofilm technology, but it has the following shortcomings: (1) It only improves the biodegradability of wastewater, but fails to convert organic nitrile into substrates usable by the subsequent anaerobic treatment system, and fails to improve the treatment efficiency and methanogenic yield of the anaerobic system. (2) The applied voltage (or current density) is conventional, which is not energy-saving or environmentally friendly. (3) Ordinary activated sludge is used and conventional aeration is carried out, but it has not been reported whether it has a positive and clear promoting effect on the subsequent anaerobic system.

[0005] Therefore, developing an efficient, economical, and easy-to-operate method for treating nitrile-containing chemical wastewater to reduce its negative impact on anaerobic treatment systems is a pressing technical problem in the field of wastewater treatment. Summary of the Invention

[0006] 1. The problem to be solved

[0007] In view of the technical problems in the prior art of using electrocatalytic internal circulation aerated biological filter pretreatment for nitrile wastewater, such as poor conductivity and biodegradation efficiency of biological packing material, and the failure to convert organic nitrile into usable substrates while only improving the biodegradability of wastewater, this invention provides an activated carbon composition loaded with microorganisms.

[0008] Furthermore, the present invention also provides a pretreatment device for nitrile-containing wastewater;

[0009] In addition, the present invention also provides a pretreatment process for nitrile-containing wastewater.

[0010] 2. Technical Solution

[0011] The technical solution adopted in this invention is as follows:

[0012] Based on the purpose of this invention, the first aspect of this invention provides an activated carbon composition loaded with microorganisms, comprising activated carbon loaded with Shewanella Oneida and activated carbon loaded with Rhodococcus turbidus; wherein the mass ratio of the activated carbon loaded with Shewanella Oneida to the activated carbon loaded with Rhodococcus turbidus is 1:2 to 1:3.

[0013] The number of Shewanella bacteria in Lake Oneida was 10. 9 ~10 10 CFU / g; the number of turbid Rhodococcus bacteria was 10. 9 ~10 10 CFU / g.

[0014] As described herein, *Shewanella oneda* can form a biofilm in the electrostatic system, adhering and accumulating on the electrode surface. When the nitrile wastewater pretreatment device is energized, granular activated carbon forms numerous microelectrodes, and *Shewanella oneda* attaches to the activated carbon surface, simultaneously secreting large amounts of extracellular polymers to aid in the colonization of *Rhodococcus turbidus*. Furthermore, *Shewanella oneda* possesses excellent electron transport capabilities, enhancing conductivity. *Rhodococcus turbidus* can produce nitrile hydratase and amidase, catalyzing the degradation and transformation of organic nitrile in the wastewater, thus eliminating the bio-inhibitory toxicity of chemical wastewater and facilitating efficient treatment by subsequent anaerobic systems.

[0015] As described herein, the functions of activated carbon are: (1) to serve as a colonization carrier for functional microorganisms, ensuring that functional microorganisms are not easily lost; and (2) to have a conductive effect when combined with electrotreatment. When filled in a pretreatment device for acrylonitrile-containing wastewater, it will form a large number of microelectrodes after being energized, which improves the reaction efficiency and also helps to accelerate the formation of biofilm of Shewanella osmosis in Lake Oneida.

[0016] According to any embodiment of the first aspect of the present invention, the microbial-loaded activated carbon composition, wherein the *Shewanella oneidensis* is deposited at the China Industrial Microbial Culture Collection Center, accession number CICC 25104; and the *Rhodococcus opacus* is deposited at the American Type Culture Collection, accession number ATCC 51882.

[0017] According to any embodiment of the first aspect of the present invention, the activated carbon composition loaded with microorganisms has a particle size of 5-10 mm for the activated carbon loaded with *Shewanella oneda* and a particle size of 2-6 mm for the activated carbon loaded with *Rhodococcus turbidus*.

[0018] Preparation method of activated carbon composition loaded with microorganisms:

[0019] Shewanella Oneida was inoculated into tryptone soybean broth and cultured at 30°C until the logarithmic growth phase. Sterile activated carbon granules (5–10 mm in diameter) were then added to the culture at a rate of 100 g per liter of culture. After incubation for 10–16 hours, the activated carbon granules were removed and air-dried in a cool place until the Shewanella Oneida count on the activated carbon was 10⁻⁶. 9 ~10 10 CFU / g was used to obtain activated carbon loaded with Shewanella from Lake Oneida.

[0020] *Rhodococcus turbidus* was inoculated into tryptone soybean broth medium and cultured at 26°C until the logarithmic growth phase. Sterile activated carbon granules with a particle size of 2–6 mm were then added to the bacterial culture at a rate of 100 g per liter of culture. After incubation for 16–24 hours, the activated carbon granules were removed and air-dried in a cool place until the number of *Rhodococcus turbidus* on the activated carbon was 10-1. 9 ~10 10 CFU / g yielded activated carbon loaded with turbid Rhodococcus.

[0021] Activated carbon loaded with Shewanella from Lake Oneida and activated carbon loaded with Rhodococcus turbidus were mixed uniformly at a mass ratio of 1:2 to 1:3 to obtain a microbial-loaded activated carbon composition.

[0022] Based on the purpose of this invention, a second aspect of this invention provides a pretreatment device for nitrile-containing wastewater, including a device body, wherein an anode and a cathode are arranged in parallel in the device body, and the anode and cathode are connected by a power source.

[0023] The space between the anode and cathode is filled with the activated carbon composition loaded with microorganisms; the device body is also equipped with a micro-nano bubble generator.

[0024] Preferably, the lower part of the device body is provided with a water inlet pipe, and the upper part of the device body is provided with a water outlet pipe.

[0025] Preferably, the anode is a ruthenium-iridium-titanium electrode, and the cathode is a stainless steel electrode.

[0026] Preferably, a screen is also provided at the water outlet pipe.

[0027] According to any embodiment of the second aspect of the present invention, in the acrylonitrile-containing wastewater pretreatment apparatus, the filling volume of the activated carbon composition loaded with microorganisms accounts for 1 / 2 to 2 / 3 of the volume of the apparatus body.

[0028] Based on the objectives of this invention, a third aspect of this invention provides a pretreatment process for nitrile-containing wastewater, using the aforementioned nitrile-containing wastewater pretreatment device, comprising the following steps:

[0029] S1. Introduce nitrile-containing wastewater into the main body of the device, turn on the power supply, and keep the micro-nano bubble generator off;

[0030] S2. Turn off the power supply, and the micro / nano bubble generator starts to operate;

[0031] S3. Turn off the micro-nano bubble generator and let it stand to settle.

[0032] According to any embodiment of the second aspect of the present invention, the pretreatment process for nitrile-containing wastewater is characterized in that: in step S1, the current density on the anode and cathode is controlled to be 7-15 mA / cm². 2 .

[0033] Preferably, a DC power supply is used, and the power supply is powered on for 10 to 20 minutes.

[0034] As described herein, the electrolysis reaction using an external DC power supply has the following effects: (1) Oxidation occurs directly at the anode, oxidizing the organic matter in the wastewater. (2) The applied voltage can stimulate the activity of nitrile hydratase and amidase in Rhodococcus turbidus, which can convert organic nitrile in the wastewater into volatile organic acids. These volatile organic acids can be directly utilized by the subsequent anaerobic system, which is beneficial to improving the treatment efficiency and methanogenic yield of the subsequent anaerobic system. (3) A small amount of hydroxyl radicals can be generated at the anode, which is beneficial to the oxidative degradation of organic matter in the wastewater.

[0035] According to any embodiment of the second aspect of the present invention, the pretreatment process for nitrile-containing wastewater is characterized in that: in step S2, the particle size of the micro-nano bubbles generated by the micro-nano bubble generator is 50-100 μm.

[0036] Preferably, the ventilation operation time is 15 to 25 minutes.

[0037] As described herein, using micro-nano bubbles as a gas source has the following advantages: (1) Micro-nano bubbles have a long residence time in water, which can provide the oxygen necessary for the growth and reproduction of inoculated functional microorganisms. (2) Micro-nano bubbles can form a certain amount of hydroxyl radicals, which is beneficial for the oxidation reaction of complex compounds in chemical wastewater. (3) Micro-nano bubbles have a large specific surface area, which can adsorb organic matter and trace elements in water. After sufficient contact with functional microorganisms, it is beneficial to improve the degradation efficiency of organic matter in wastewater by microorganisms. (4) After water containing micro-nano bubbles enters the subsequent anaerobic system, it can stimulate the reproduction of facultative anaerobic microorganisms in the subsequent anaerobic system, produce more extracellular enzymes, enhance the hydrolysis and acidification process of the subsequent anaerobic system, and improve the treatment efficiency of the subsequent anaerobic system.

[0038] According to any embodiment of the second aspect of the present invention, the pretreatment process for nitrile-containing wastewater is characterized in that: in step S3, the settling time is ≥5 min.

[0039] According to any embodiment of the second aspect of the present invention, the pretreatment process for nitrile-containing wastewater is characterized by: controlling the hydraulic retention time to be 7-8 hours, controlling the pH value to be 7.2-7.8 during operation, and controlling the operating temperature to be 26-30°C.

[0040] 3. Beneficial effects

[0041] (1) The activated carbon composition loaded with microorganisms of the present invention: a. By loading an activated carbon composition containing *Shewanella oneda* and *Rhodococcus turbidus*, the synergistic effect of these two microorganisms is utilized to effectively degrade organic nitrile compounds in nitrile-containing chemical wastewater. *Shewanella oneda* has good electron transport capacity, while *Rhodococcus turbidus* can produce nitrile hydratase and amidase, which catalyze the degradation and transformation of organic nitrile compounds, thereby relieving the bioinhibitory toxicity of the wastewater. b. *Shewanella oneda* can form a biofilm in the electrostatic system and adhere to and aggregate on the electrode surface. The formation of this biofilm helps to improve conductivity, making the electrocatalytic oxidation process more efficient. c. The large amount of extracellular polymers secreted by *Shewanella oneda* helps *Rhodococcus turbidus* colonize and form a stable biofilm. This stable biofilm structure is beneficial to the long-term activity of microorganisms and the continuity of wastewater treatment. d. The number of *Shewanella oneda* and *Rhodococcus turbidus* are both above 10. 9 ~10 10 Within the CFU / g range, this high concentration of microbial load helps improve the efficiency and stability of wastewater treatment. e. It does not produce secondary pollution, making it an environmentally friendly wastewater treatment technology. Through the combination of biodegradation and electrocatalytic oxidation, organic nitrile compounds can be effectively removed while reducing the use of chemical agents. f. Bioinhibition toxicity is eliminated, which is beneficial for the efficient treatment of subsequent anaerobic systems. This not only improves the overall wastewater treatment efficiency but also helps reduce the cost of subsequent treatment.

[0042] (2) The acrylonitrile-containing wastewater pretreatment device of the present invention: a. By setting parallel anodes and cathodes and filling them with activated carbon composition loaded with microorganisms, organic pollutants in acrylonitrile-containing wastewater can be effectively degraded using electrocatalytic oxidation technology. b. The micro-nano bubble generator integrated in the device can generate a large number of micro-nano bubbles, increasing the gas-liquid contact area and improving the oxygen transfer efficiency, thereby enhancing the biological treatment effect. c. The device design simplifies the operation process, has a high degree of automation, reduces manual intervention, and at the same time, reduces maintenance costs and frequency.

[0043] (3) The pretreatment process for nitrile-containing wastewater of the present invention: a. Organic nitrile is converted into volatile organic acids, which can be directly used as substrates for anaerobic reactions, thereby improving the methanogenic capacity and COD degradation efficiency of the subsequent anaerobic system. b. Compared with traditional electrolytic cell pretreatment reactors, the applied voltage of this application is mainly used to stimulate the growth of functional microorganisms and enhance the activity of degrading enzymes, thus resulting in low power consumption and low treatment cost. c. The operation steps of this process are simple and easy to control, and the use of DC power ensures the simplicity and safety of the operation process. d. This process does not generate secondary pollution and is an environmentally friendly wastewater treatment technology that meets the requirements of green and sustainable development. e. By precisely controlling the energizing time, the particle size of micro-nano bubbles, the aeration time, and the settling time, this process ensures the high efficiency and stability of wastewater treatment.

[0044] Instruction manual illustrations

[0045] Figure 1 This is a schematic diagram of the structure of the acrylonitrile-containing wastewater pretreatment device in the embodiments of this application;

[0046] In the picture:

[0047] 1. Device body; 2. Inlet pipe; 3. Outlet pipe; 4. Anode; 5. Cathode; 6. Power supply; 7. Activated carbon composition loaded with microorganisms; 8. Micro-nano bubble generator; 9. Screen. Detailed Implementation

[0048] All references cited in this invention are incorporated herein by reference in their entirety, and in the event of any inconsistency between the meanings expressed in these references and those expressed herein, the meanings expressed herein shall prevail. Furthermore, the various terms and phrases used in this invention have their general meanings known to those skilled in the art; however, this invention still seeks to provide a more detailed explanation and interpretation of these terms and phrases, and in the event of any inconsistency between the mentioned terms and their known meanings and those expressed herein, the meanings expressed herein shall prevail.

[0049] When an item is described using the combined terms “...and / or ...", the description should be understood to include any one of the listed items and all combinations thereof.

[0050] Generally, the use of the term "about" indicates an approximation that can vary depending on the desired characteristics obtained from the disclosed subject matter and will be interpreted in a context-dependent manner based on function. Therefore, those skilled in the art will be able to interpret a degree of difference on a case-by-case basis. In some cases, the number of significant figures used when expressing a particular value can be a representative technique for determining the difference allowed by the term "about." In other cases, a gradient within a range of values ​​can be used to determine the range of differences allowed by the term "about." Furthermore, all ranges in this disclosure are inclusive and composable, and references to values ​​described within a range include every value within that range.

[0051] In this invention, the term "comprising" or "containing" indicates that various ingredients may be used together in the composition of this invention. Therefore, the terms "consistent with..." and "composed of..." are included in the term "comprising" or "containing".

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terms used herein and / or include any and all combinations of one or more of the associated listed items.

[0053] Unless otherwise stated, any feature disclosed in this specification may be replaced by other equivalent or similar features. Unless otherwise stated, each feature is merely one example of a series of equivalent or similar features. The descriptions are merely to aid in understanding the invention and should not be construed as limiting the invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0054] The present invention will be further described below with reference to specific embodiments.

[0055] Example 1

[0056] This embodiment provides an activated carbon composition loaded with microorganisms and a pretreatment process for nitrile-containing wastewater, implemented using a nitrile-containing wastewater pretreatment device, the structural schematic of which is shown below. Figure 1 As shown,

[0057] The device body 1 of the nitrile wastewater pretreatment device includes an inlet pipe 2 located at the bottom and an inlet pipe 3 located at the top. Electrode plates, namely an anode 4 and a cathode 5, are inserted into the device body 1 and connected to a power supply 6. In this embodiment, a DC power supply is used. The anode 4 is a ruthenium-iridium-titanium electrode, and the cathode 5 is a stainless steel electrode. The anode 4 and cathode 5 are placed parallel to each other.

[0058] The space between the anode 4 and the cathode 5 is filled with activated carbon composition 7 loaded with microorganisms. The volume of activated carbon composition 7 loaded with microorganisms accounts for 1 / 2 to 2 / 3 of the effective volume. In this example, it is 2 / 3. The remaining volume is filled with the acrylonitrile-containing chemical wastewater to be treated.

[0059] A micro-nano bubble generator 8 is installed at the bottom of the device body 1.

[0060] In this embodiment, a water bath jacket is provided on the outside of the device body 1, which can regulate the operating temperature inside the device body 1.

[0061] A screen 9 is installed below the water outlet pipe 3 of the device body 1 to intercept the activated carbon composition 7 loaded with microorganisms and prevent the activated carbon composition 7 loaded with microorganisms from being lost.

[0062] Preparation method of activated carbon composition 7 loaded with microorganisms in device body 1:

[0063] Shewanella Oneida was inoculated into tryptone soybean broth and cultured at 30°C until the logarithmic growth phase. Sterile activated carbon granules (5–10 mm in diameter) were then added to the culture at a rate of 100 g per liter of culture. After incubation for 10–16 hours, the activated carbon granules were removed and air-dried in a cool place until the Shewanella Oneida count on the activated carbon was 10⁻⁶. 9 ~10 10 CFU / g was used to obtain activated carbon loaded with Shewanella from Lake Oneida.

[0064] *Rhodococcus turbidus* was inoculated into tryptone soybean broth medium and cultured at 26°C until the logarithmic growth phase. Sterile activated carbon granules with a particle size of 2–6 mm were then added to the bacterial culture at a rate of 100 g per liter of culture. After incubation for 16–24 hours, the activated carbon granules were removed and air-dried in a cool place until the number of *Rhodococcus turbidus* on the activated carbon was 10-1. 9 ~10 10 CFU / g yielded activated carbon loaded with turbid Rhodococcus.

[0065] Activated carbon loaded with *Shewanella oneneda* and activated carbon loaded with *Rhodococcus turbidus* were uniformly mixed at a mass ratio of 1:2 to 1:3 to obtain activated carbon composition 7 loaded with microorganisms. The ratio used in this example is 1:2.

[0066] The pretreatment process steps for nitrile-containing wastewater are as follows:

[0067] The acrylonitrile-containing chemical wastewater is continuously and evenly introduced into the inlet pipe 2 at the bottom of the main unit 1, with the hydraulic retention time controlled at 8 hours. During operation, the pH inside the acrylonitrile-containing wastewater pretreatment unit is controlled at 7.8, and the operating temperature of the acrylonitrile-containing wastewater pretreatment unit can be controlled at 30℃. The operation of the acrylonitrile-containing wastewater pretreatment unit is divided into 3 stages, which are continuously cyclical.

[0068] Stage 1: The external DC power supply 6 of the nitrile wastewater pretreatment device is powered on, the micro / nano bubble generator 8 is not operating, and when the DC power supply 9 is powered on, the current density on the anode 4 and cathode 5 is controlled to be 7 mA / cm². 2 The power-on time lasts for 15 minutes.

[0069] Phase 2: The external DC power supply 9 of the nitrile wastewater pretreatment device is disconnected, and the micro-nano bubble generator 8 starts to run, introducing micro-nano bubbles with a particle size of 50-100μm into the nitrile wastewater pretreatment device for 20 minutes.

[0070] Phase 3: The external DC power supply 9 and the micro-nano bubble generator 8 of the nitrile wastewater pretreatment device are not running, and the wastewater is allowed to settle for 5 minutes.

[0071] The COD and acrylonitrile content of the nitrile-containing wastewater before and after the pretreatment process were measured as follows:

[0072]

[0073] Wastewater pretreated by a nitrile-containing wastewater pretreatment device was added to anaerobic sludge at a volume ratio of 1:4. After thorough mixing, the mixture was incubated at 35°C for 48 hours. The cumulative methane production, coenzyme F420 concentration, and COD removal rate of the anaerobic sludge from the wastewater were then measured. The results are as follows:

[0074]

[0075] Example 2

[0076] The activated carbon composition loaded with microorganisms and the pretreatment process for nitrile-containing wastewater provided in this embodiment use the nitrile-containing wastewater pretreatment device in Example 1. The specific steps are as follows:

[0077] Shewanella Oneida was inoculated into tryptone soybean broth and cultured at 30°C until the logarithmic growth phase. Sterile activated carbon granules (5 mm diameter) were then added to the culture at a rate of 100 g per liter of culture. After incubation for 10 hours, the activated carbon granules were removed and air-dried in a cool place until the number of Shewanella Oneida on the activated carbon was approximately 10. 9 CFU / g was used to obtain activated carbon loaded with *Shewanella oneda*. *Rhodococcus turbidus* was inoculated into tryptone soybean broth medium and cultured at 26°C until the logarithmic growth phase. Sterile activated carbon particles with a particle size of 2 mm were added to the bacterial culture at a rate of 100 g per liter of bacterial culture. After incubation for 16 hours, the activated carbon particles were removed and air-dried in a cool place until the number of *Rhodococcus turbidus* on the activated carbon was approximately 10. 9CFU / g was used to obtain activated carbon loaded with Rhodococcus turbidus. Activated carbon loaded with Shewanella oneida and activated carbon loaded with Rhodococcus turbidus were mixed uniformly at a mass ratio of 1:3 to obtain activated carbon composition 7 loaded with microorganisms.

[0078] The activated carbon composition 7 loaded with microorganisms occupies half the volume of the main body 1 of the device, and the remaining volume is filled with the acrylonitrile-containing chemical wastewater to be treated. The acrylonitrile-containing chemical wastewater is continuously and uniformly introduced into the inlet pipe 2 at the bottom of the acrylonitrile-containing wastewater pretreatment device, with a hydraulic retention time controlled at 7 hours. During operation, the pH inside the acrylonitrile-containing wastewater pretreatment device is controlled at 7.2, and the operating temperature is controlled at 30℃. The operation of the acrylonitrile-containing wastewater pretreatment device is divided into three stages, continuously cyclically carried out.

[0079] Stage 1: The external DC power supply 6 of the nitrile wastewater pretreatment device is powered on, the micro / nano bubble generator 8 is not operating, and the current density on the control electrode is 15 mA / cm² when the DC power supply 6 is powered on. 2 The power-on time lasts for 15 minutes.

[0080] Phase 2: The external DC power supply 6 of the nitrile wastewater pretreatment device is disconnected, and the micro-nano bubble generator 8 starts to run, introducing micro-nano bubbles with a particle size of 50-100μm into the nitrile wastewater pretreatment device for 20 minutes.

[0081] Phase 3: The external DC power supply 6 and the micro-nano bubble generator 8 of the acrylonitrile-containing wastewater pretreatment device are not running, and the wastewater is allowed to settle for 5 minutes.

[0082] The COD and acrylonitrile content of the nitrile-containing wastewater before and after the pretreatment process were measured as follows:

[0083]

[0084] Wastewater pretreated by a nitrile-containing wastewater pretreatment device was added to anaerobic sludge at a volume ratio of 1:4. After thorough mixing, the mixture was incubated at 35°C for 48 hours. The cumulative methane production, coenzyme F420 concentration, and COD removal rate of the anaerobic sludge from the wastewater were then measured. The results are as follows:

[0085]

[0086] Comparative Example 1

[0087] The acrylonitrile-containing wastewater treatment device in this comparative example is basically the same as that in Example 1, except that ordinary activated carbon is used to fill the space between the electrodes, with the activated carbon filling volume occupying 2 / 3 of the effective volume of the device. The remaining volume is filled with the acrylonitrile-containing chemical wastewater to be treated. The acrylonitrile-containing chemical wastewater is continuously and uniformly introduced from the bottom of the device, with the hydraulic retention time controlled at 8 hours. During operation, the pH inside the acrylonitrile-containing wastewater treatment device is controlled at 7.5, and the operating temperature is controlled at 30°C. The operation is divided into 3 stages, which are continuously cyclical.

[0088] Phase 1: When the device is powered by an external DC power supply, the micro / nano bubble generator is not operating. When the DC power supply is powered on, the current density on the control electrode is 7 mA / cm². 2 The power-on time lasts for 15 minutes.

[0089] Phase 2: The external DC power supply to the device is turned off, and the micro-nano bubble generator starts to run, introducing micro-nano bubbles with a particle size of 50-100μm into the device. The aeration time is 20 minutes.

[0090] Phase 3: The external DC power supply and micro / nano bubble generator are not running. The device is left to stand and settle for 5 minutes.

[0091] The COD and acrylonitrile content before and after treatment by the measuring device are as follows:

[0092]

[0093] The treated wastewater was added to the anaerobic sludge at a volume ratio of 1:4. After thorough mixing, the mixture was incubated at 35°C for 48 hours. The cumulative methane production, coenzyme F420 concentration, and COD removal rate of the anaerobic sludge from the wastewater were then measured. The results are as follows:

[0094]

[0095] Comparative Example 2

[0096] The activated carbon composition loaded with microorganisms in this comparative example was prepared as follows: *Shewanella oneda* was inoculated into tryptone soybean broth medium and cultured at 30°C until the logarithmic growth phase. Sterile activated carbon particles with a particle size of 10 mm were added to the bacterial solution at a rate of 100 g per liter of bacterial solution. After incubation for 16 hours, the activated carbon particles were removed and air-dried in a cool place until the number of *Shewanella oneda* on the activated carbon was approximately 10. 10CFU / g was used to obtain activated carbon loaded with *Shewanella oneda*. *Rhodococcus turbidus* was inoculated into tryptone soybean broth medium and cultured at 26°C until the logarithmic growth phase. Sterile activated carbon particles with a particle size of 5 mm were added to the bacterial culture at a rate of 100 g per liter of bacterial culture. After incubation for 24 hours, the activated carbon particles were removed and air-dried in a cool place until the number of *Rhodococcus turbidus* on the activated carbon was approximately 10. 10 CFU / g was used to obtain activated carbon loaded with Rhodococcus turbidus. Activated carbon loaded with Shewanella oneida and activated carbon loaded with Rhodococcus turbidus were mixed uniformly at a mass ratio of 1:2 to obtain a microbial-loaded activated carbon composition.

[0097] The wastewater pretreatment device in this comparative example is basically the same as in Example 1, except that it does not use a micro-nano bubble generator, but instead uses aeration pipes and a conventional air compressor for aeration and oxygenation. The space between the electrodes is filled with a microbially loaded activated carbon composition, which occupies 2 / 3 of the effective volume of the device. The remaining volume is filled with the acrylonitrile-containing chemical wastewater to be treated. The acrylonitrile-containing chemical wastewater is continuously and uniformly introduced from the bottom of the device, with a hydraulic retention time controlled at 8 hours. During operation, the pH inside the device is controlled at 7.5, and the operating temperature is controlled at 30°C. The device operates in three stages, continuously cycling through each stage.

[0098] Phase 1: The device is powered by an external DC power supply, the aeration air compressor is not running, and the current density on the control electrode is 7 mA / cm² when the DC power supply is on. 2 The power-on time lasts for 15 minutes.

[0099] Phase 2: The external DC power supply to the device is disconnected, the aeration air compressor starts running, and air is introduced into the device at a flow rate of 20L / min for 20min.

[0100] Phase 3: The external DC power supply and aeration air compressor of the device are not running. Let the device stand and settle for 5 minutes.

[0101] The COD and acrylonitrile contents before and after the biological pretreatment were measured as follows:

[0102]

[0103] The treated wastewater was added to the anaerobic sludge at a volume ratio of 1:4. After thorough mixing, the mixture was incubated at 35°C for 48 hours. The cumulative methane production, coenzyme F420 concentration, and COD removal rate of the anaerobic sludge from the wastewater were then measured. The results are as follows:

[0104]

[0105] Comparative Example 3

[0106] The activated carbon composition loaded with microorganisms in this comparative example was prepared as follows: *Shewanella oneda* was inoculated into tryptone soybean broth medium and cultured at 30°C until the logarithmic growth phase. Sterile activated carbon particles with a particle size of 10 mm were added to the bacterial solution at a rate of 100 g per liter of bacterial solution. After incubation for 16 hours, the activated carbon particles were removed and air-dried in a cool place until the number of *Shewanella oneda* on the activated carbon was approximately 10. 10 CFU / g was used to obtain activated carbon loaded with *Shewanella oneda*. *Rhodococcus turbidus* was inoculated into tryptone soybean broth medium and cultured at 26°C until the logarithmic growth phase. Sterile activated carbon particles with a particle size of 5 mm were added to the bacterial culture at a rate of 100 g per liter of bacterial culture. After incubation for 24 hours, the activated carbon particles were removed and air-dried in a cool place until the number of *Rhodococcus turbidus* on the activated carbon was approximately 10. 10 CFU / g was used to obtain activated carbon loaded with Rhodococcus turbidus. Activated carbon loaded with Shewanella oneneida and activated carbon loaded with Rhodococcus turbidus were mixed uniformly at a mass ratio of 1:2 to obtain a microbial-loaded activated carbon composition.

[0107] The acrylonitrile-containing wastewater pretreatment device in this comparative example is basically the same as in Example 1. The space between the electrodes is filled with an activated carbon composition loaded with microorganisms, occupying 2 / 3 of the effective volume of the device. The remaining volume is filled with the acrylonitrile-containing chemical wastewater to be treated. The acrylonitrile-containing chemical wastewater is continuously and uniformly introduced from the bottom of the acrylonitrile-containing wastewater pretreatment device, with a hydraulic retention time controlled at 8 hours. During operation, the pH inside the acrylonitrile-containing wastewater pretreatment device is controlled at 7.5, and the operating temperature is controlled at 30°C. An external DC power supply is continuously powered during operation of the acrylonitrile-containing wastewater pretreatment device, and the current density on the electrodes is controlled at 20 mA / cm². 2 .

[0108] The COD and acrylonitrile contents before and after biological pretreatment were measured as follows:

[0109]

[0110] Pretreated wastewater was added to anaerobic sludge at a volume ratio of 1:4. After thorough mixing, the mixture was incubated at 35°C for 48 hours. The cumulative methane production, coenzyme F420 concentration, and COD removal rate of the anaerobic sludge from the wastewater were then measured. The results are as follows:

[0111]

[0112] Comparative Example 4

[0113] Shewanella Oneida was inoculated into tryptone soybean broth and cultured at 30°C until the logarithmic growth phase. Sterile activated carbon granules (10 mm diameter) were then added to the bacterial culture at a rate of 100 g per liter of culture. After incubation for 16 hours, the activated carbon granules were removed and air-dried in a cool place until the number of Shewanella Oneida on the activated carbon was approximately 10. 10 CFU / g, denoted as Functional Activated Carbon A.

[0114] The electrodes of the biological pretreatment reactor are filled with functional activated carbon A, which occupies 2 / 3 of the effective volume. The remaining volume is filled with the acrylonitrile-containing chemical wastewater to be treated. The acrylonitrile-containing chemical wastewater is continuously and uniformly introduced from the bottom of the reactor, with a hydraulic retention time controlled at 8 hours. During operation, the pH inside the reactor is controlled at 7.8, and the reactor operating temperature is controlled at 30℃. The reactor operation is divided into three stages, which are continuously cyclical. Stage 1: The reactor is powered by an external DC power supply, the micro / nano bubble generator is not running, and the current density on the electrodes is controlled at 7 mA / cm² when the DC power supply is on. 2 Phase 1: The power supply to the reactor is turned off for 15 minutes. Phase 2: The external DC power supply to the reactor is turned off, and the micro / nano bubble generator starts running, introducing micro / nano bubbles with a particle size of 50-100 μm into the reactor for 20 minutes. Phase 3: The external DC power supply to the reactor and the micro / nano bubble generator are both turned off, and the reactor is allowed to settle for 5 minutes.

[0115] The COD and acrylonitrile contents before and after treatment in the biological pretreatment reactor were measured as follows:

[0116]

[0117] Wastewater treated by the biological pretreatment reactor was added to anaerobic sludge at a volume ratio of 1:4. After thorough mixing, the mixture was incubated at 35°C for 48 hours. The cumulative methane production, coenzyme F420 concentration, and COD removal rate of the anaerobic sludge from the wastewater were then measured. The results are as follows:

[0118]

[0119] Comparative Example 5

[0120] Rhodococcus turbidus was inoculated into tryptone soybean broth medium and cultured at 26°C until the logarithmic growth phase. Sterile activated carbon granules with a particle size of 5 mm were added to the bacterial solution at a rate of 100 g per liter of bacterial solution. After incubation for 24 hours, the activated carbon granules were removed and air-dried in a cool place until the number of Rhodococcus turbidus on the activated carbon was approximately 10¹⁰ CFU / g. This activated carbon was designated as functional activated carbon B.

[0121] The electrodes of the biological pretreatment reactor are filled with functional activated carbon B, which occupies 2 / 3 of the effective volume. The remaining volume is filled with the acrylonitrile-containing chemical wastewater to be treated. The acrylonitrile-containing chemical wastewater is continuously and uniformly introduced from the bottom of the reactor, with a hydraulic retention time controlled at 8 hours. During operation, the pH inside the reactor is controlled at 7.8, and the reactor operating temperature is controlled at 30℃. The reactor operation is divided into three stages, continuously cyclically. Stage 1: The reactor is powered by an external DC power supply, but the micro / nano bubble generator is not running. When the DC power supply is on, the current density on the control electrodes is 7 mA / cm², and the energizing time is 15 minutes. Stage 2: The external DC power supply to the reactor is de-energized, and the micro / nano bubble generator starts running, introducing micro / nano bubbles with a particle size of 50–100 μm into the reactor for 20 minutes. Stage 3: The reactor is de-energized by both the external DC power supply and the micro / nano bubble generator, and the reactor is allowed to settle for 5 minutes.

[0122] The COD and acrylonitrile contents before and after treatment in the biological pretreatment reactor were measured as follows:

[0123]

[0124] Wastewater treated by the biological pretreatment reactor was added to anaerobic sludge at a volume ratio of 1:4. After thorough mixing, the mixture was incubated at 35°C for 48 hours. The cumulative methane production, coenzyme F420 concentration, and COD removal rate of the anaerobic sludge from the wastewater were then measured. The results are as follows:

[0125]

Claims

1. A pretreatment process for nitrile-containing wastewater, characterized in that: Use a pretreatment device for nitrile-containing wastewater: The device includes a device body (1), in which an anode (4) and a cathode (5) are arranged in parallel, and the anode (4) and the cathode (5) are connected by a power supply (6); The space between the anode (4) and the cathode (5) is filled with an activated carbon composition (7) loaded with microorganisms; the device body (1) is also provided with a micro-nano bubble generator (8). The microbial-loaded activated carbon composition (7) includes activated carbon loaded with Shewanella Oneida and activated carbon loaded with Rhodococcus turbidus; the mass ratio of the activated carbon loaded with Shewanella Oneida and the activated carbon loaded with Rhodococcus turbidus is 1:2 to 1:

3. The number of Shewanella bacteria in Lake Oneida was 10. 9 ~10 10 CFU / g; the number of turbid Rhodococcus bacteria was 10. 9 ~10 10 CFU / g; The *Shewanella oneidensis* of Lake Oneida is deposited at the China Industrial Microbial Culture Collection Center, accession number CICC 25104; the *Rhodococcus opacus* is deposited at the American Type Culture Collection, accession number ATCC 51882. include step: S1. Introduce acrylonitrile-containing wastewater into the main body of the device (1), turn on the power supply (6), and keep the micro-nano bubble generator (8) off; S2. Turn off the power supply (6), and the micro-nano bubble generator (8) starts to run; S3. Turn off the micro-nano bubble generator (8) and let it stand to settle.

2. The pretreatment process for nitrile-containing wastewater according to claim 1, characterized in that: The activated carbon loaded with Lake Oneida Shewanella has a particle size of 5-10 mm; the activated carbon loaded with Rhodococcus turbidus has a particle size of 2-6 mm.

3. The pretreatment process for nitrile-containing wastewater according to claim 1, characterized in that: The filling volume of the microbial-loaded activated carbon composition (7) accounts for 1 / 2 to 2 / 3 of the volume of the device body (1).

4. The pretreatment process for nitrile-containing wastewater according to claim 1, characterized in that: In step S1, the current density on the anode (4) and cathode (5) is controlled to be 7~15 mA / cm. 2 .

5. The pretreatment process for nitrile-containing wastewater according to claim 1, characterized in that: In step S2, the micro-nano bubble generator (8) produces micro-nano bubbles with a particle size of 50~100 μm.

6. The pretreatment process for nitrile-containing wastewater according to claim 1, characterized in that: In step S3, the settling time is ≥5 min.

7. The pretreatment process for nitrile-containing wastewater according to any one of claims 4-6, characterized in that: The hydraulic retention time is controlled at 7-8 h, the pH value is controlled at 7.2-7.8 during operation, and the operating temperature is controlled at 26-30 ℃.

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