A coking wastewater treatment device and treatment method

Abstract

The application discloses a coking wastewater treatment device and method, and belongs to the technical field of industrial organic wastewater treatment, and solves the problems of insufficient oxygen supply and low mass transfer efficiency in the traditional aerobic bacteria culture process in the prior art. In the device, a biofilm carrier is filled in a reactor, a liquid inlet of a micro-nano bubble generator is connected with the reactor, a micro-nano bubble outlet of the micro-nano bubble generator is connected with the reactor, and an air inlet of the micro-nano bubble generator is connected with the atmosphere. The method comprises the following steps: enriching mixed bacteria from activated sludge and domesticating the mixed bacteria; filling the biofilm carrier in the reactor, dividing coking wastewater to be treated into multiple portions, adding nutrients to at least one portion of the coking wastewater to be treated, and then injecting the coking wastewater into the reactor, inoculating the domesticated seed liquid into the reactor, and performing biofilm formation of the mixed bacteria on the biofilm carrier; introducing micro-nano bubbles into the reactor; and adding the remaining coking wastewater into the reactor after adding nutrients, and then injecting the coking wastewater into the reactor for degradation. The application can be used for treating coking wastewater.

Description

Technical Field

[0001] This invention belongs to the field of industrial organic wastewater treatment technology, and particularly relates to a treatment device and method for coking wastewater. Background Technology

[0002] In actual production processes, high concentrations of organic matter (e.g., containing phenols, polycyclic aromatic hydrocarbons, and heterocyclic compounds) are both a hot topic and a challenge in coking wastewater treatment.

[0003] Because coking wastewater contains many biological inhibitors and recalcitrant substances, traditional aerobic coking wastewater treatment devices typically include an air supply unit 1 and a reactor 2. (See...) Figure 1 The gas supply unit 1 supplies oxygen into the reactor 2 to provide oxygen for the aerobic bacteria. However, due to insufficient oxygen supply and low mass transfer efficiency during the aerobic bacteria cultivation process, the treatment effect on organic matter is limited. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a treatment device and method for coking wastewater, which solves the problems of insufficient oxygen supply and low mass transfer efficiency in the traditional aerobic bacteria cultivation process in the prior art.

[0005] The objective of this invention is mainly achieved through the following technical solutions:

[0006] The present invention provides a coking wastewater treatment device including a reactor, a micro-nano bubble generator and a biofilm carrier. The biofilm carrier is filled in the reactor. The liquid inlet of the micro-nano bubble generator is connected to the reactor, the micro-nano bubble outlet of the micro-nano bubble generator is connected to the reactor, and the air inlet of the micro-nano bubble generator is connected to the atmosphere.

[0007] Furthermore, the micro-nano bubble generator's micro-nano bubble outlet is located at the bottom of the reactor.

[0008] Furthermore, it also includes a circulation pump located between the liquid inlet of the micro / nano bubble generator and the reactor.

[0009] Furthermore, a filter screen is provided at the outlet where the reactor connects to the circulating pump, on the connecting pipeline between the circulating pump and the reactor, and / or at the inlet of the circulating pump.

[0010] Furthermore, the circulating pump and the connecting pipeline are sealed together by a sealing connector.

[0011] The present invention also provides a method for treating coking wastewater, using the above-mentioned coking wastewater treatment apparatus, and the treatment method includes the following steps:

[0012] Step 1: Enrich the mixed microbial community from the activated sludge, acclimate the mixed microbial community to obtain the acclimatized seed liquid;

[0013] Step 2: Fill the reactor with biofilm carrier, inoculate the acclimated seed liquid into the reactor, divide the coking wastewater to be treated into multiple portions, add nutrients to at least one portion of the coking wastewater and inject it into the reactor, inoculate the acclimated seed liquid into the reactor, and carry out biofilm formation of mixed microorganisms on the biofilm carrier.

[0014] Step 3: Introduce micro-nano bubbles into the reactor;

[0015] Step 4: Add nutrients to the remaining coking wastewater and inject it into the reactor for degradation, thus completing the treatment of the coking wastewater.

[0016] Furthermore, in step 2, the film attachment includes the following steps:

[0017] Step 21: Fill the reactor with a biofilm carrier;

[0018] Step 22: Inoculate the domesticated seed solution into the reactor;

[0019] Step 23: Divide the coking wastewater to be treated into multiple portions, add nutrients to at least one portion of the coking wastewater and inject it into the reactor to aerate and react the reactor.

[0020] Step 24: Maintain aeration and replace the existing coking wastewater containing nutrients in the reactor with another batch of coking wastewater containing nutrients to be treated, and carry out the reaction.

[0021] Step 25: Repeat step 24 until a biofilm with aerobic bacteria attached to its surface is formed on the biofilm carrier.

[0022] Furthermore, in step 23, after adding nutrients to the coking wastewater to be treated and before dividing the nutrient-containing coking wastewater into multiple portions, the following steps are also included:

[0023] Adjust the pH of the coking wastewater containing nutrients to 6.5–7.5.

[0024] Furthermore, aeration includes the following steps:

[0025] Step 231: Aerate the reactor with micro-nano bubbles;

[0026] Step 232: Aerate the reactor with air;

[0027] Step 233: Repeat steps 231 and 232 until step 25 is completed.

[0028] Furthermore, the micro-nano bubble aeration pressure is 0.3–0.6 MPa, the micro-nano bubble aeration inlet flow rate is 50–70 mL / min, and the micro-nano bubble aeration time is 1.5–2.5 h.

[0029] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0030] A) The coking wastewater treatment device provided by the present invention uses a micro-nano bubble generator to replace the traditional aerator to increase oxygen in the reactor. The micro-nano bubbles can exist in the reactor for a long time without breaking, thereby greatly improving the oxygen mass transfer efficiency.

[0031] B) In the coking wastewater treatment device provided by the present invention, a biofilm carrier for biofilm formation is provided in the reactor. Aerobic bacteria grow on the biofilm carrier and basically do not produce sludge. Therefore, it is not necessary to set up a stirring device in the reactor. While achieving the effect of oxygen supply, it can effectively avoid the inactivation of aerobic bacteria due to shear force and mechanical force caused by stirring. Furthermore, since the aerobic bacteria are solidified on the biofilm carrier, they will not enter the micro-nano bubble generator, thereby avoiding the aerobic bacteria from being subjected to high pressure and high impact force in the micro-nano bubble generator.

[0032] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0033] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0034] Figure 1 This is a schematic diagram of the structure of an air aeration reactor in the prior art;

[0035] Figure 2 This is a schematic diagram of the structure of the coking wastewater treatment device provided by the present invention;

[0036] Figure 3 This is a schematic diagram of the sealing connection component in the coking wastewater treatment device provided by the present invention;

[0037] Figure 4 This is a suspension diagram of the seed liquid after domestication in Example 1 of the present invention;

[0038] Figure 5 This is an image of the polyurethane sponge after the membrane attachment is completed in Embodiment 1 of the present invention;

[0039] Figure 6 This is a comparison chart of the phenol removal rates of Example 1 and Comparative Example 1 of the present invention.

[0040] Figure label:

[0041] 1-Gas supply unit; 2-Reactor; 3-Micro-nano bubble generator; 4-Circulation pump; 5-Rotor; 6-Connecting protrusion; 7-Rigid blade ring; 8-Elastic ring. Detailed Implementation

[0042] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0043] Microbubbles are tiny bubbles with diameters between the micro and nanometer scale. They possess advantages such as long residence time in water, high mass transfer efficiency, and high zeta potential, and are widely used in aquaculture, crop growth, and wastewater treatment. This invention provides oxygen to aerobic bacteria through air microbubbles, promoting their growth and the degradation of organic pollutants.

[0044] This invention provides a treatment device for coking wastewater, see [link to device]. Figures 2 to 3 The system includes a reactor 2, a micro / nano bubble generator 3, and a biofilm carrier. The biofilm carrier is filled in the reactor 2. The liquid inlet of the micro / nano bubble generator 3 is connected to the reactor 2 through a circulating pump 4. The micro / nano bubble outlet of the micro / nano bubble generator 3 is connected to the reactor 2. The air inlet of the micro / nano bubble generator 3 is connected to the atmosphere.

[0045] Traditional aeration methods produce large bubbles that rise rapidly, grow larger, and then burst, limiting oxygen mass transfer. In contrast, the coking wastewater treatment device provided by this invention uses a micro-nano bubble generator instead of a traditional aerator to oxygenate reactor 2. These micro-nano bubbles can persist for extended periods in the acclimated seed liquid without bursting, thus significantly improving oxygen mass transfer efficiency.

[0046] Meanwhile, in existing technologies, no solidification device is installed in reactor 2, and the aerobic bacteria are in a free state in reactor 2. This results in the generation of a large amount of sludge during the treatment of coking wastewater, preventing the aerobic bacteria at the bottom of the sludge from contacting oxygen and thus preventing their survival. Therefore, existing technologies often require a stirring device in the reactor. In the coking wastewater treatment device of this invention, a biofilm carrier for biofilm formation is provided in reactor 2. The aerobic bacteria grow on the biofilm carrier and basically do not produce sludge. Therefore, it is not necessary to install a stirring device in reactor 2. While achieving the effect of oxygen supply, it can effectively avoid the inactivation of aerobic bacteria due to shear force and mechanical force caused by stirring. Furthermore, since the aerobic bacteria are solidified on the biofilm carrier, they will not enter the micro-nano bubble generator 3, thus avoiding the high pressure and high impact force of the micro-nano bubble generator 3 on the aerobic bacteria.

[0047] It is understandable that, in order to achieve the overall circulation of coking wastewater in the treatment device, the above-mentioned treatment device also includes a circulation pump 4 located between the inlet of the micro-nano bubble generator 3 and the reactor 2. That is, the outlet of the reactor 2 is connected to the inlet of the circulation pump 4, and the outlet of the circulation pump 4 is connected to the inlet of the micro-nano bubble generator 3.

[0048] In order to further increase the residence time of nanobubbles in reactor 2, the microbubble outlet of the aforementioned micro-nanobubble generator 3 is located at the bottom of reactor 2.

[0049] To prevent solids in the coking wastewater from clogging the micro-circulation pump 4 and / or the nanobubble generator, filter screens are provided at the outlet of the reactor 2 connected to the circulation pump 4, on the connecting pipe between the circulation pump 4 and the reactor 2, and / or at the inlet of the circulation pump 4. The filter screens can effectively filter and treat the solids in the coking wastewater.

[0050] It is understandable that the flow of coking wastewater to be treated is involved between the circulating pump 4 and the connecting pipeline, therefore, the two can be sealed together by a sealing connector.

[0051] For example, see Figure 3 The sealing connector includes a sealing ring, a clamp, and multiple rotating rods 5. The sealing ring is located at the end of the connecting pipe. The multiple rotating rods 5 are connected to each other by the clamp to form a whole. One end of the rotating rod 5 is defined as the pivot end, and the other end is the connecting end. The pivot end of the rotating rod 5 is rotatably connected to the outer wall of the connecting pipe. The connecting end of the rotating rod 5 is provided with a connecting protrusion 6 facing the circulation pump 4. The circulation pump 4 is provided with a connecting groove corresponding to the position of the connecting protrusion 6. Along the direction gradually away from the rotating rod 5, the connecting protrusion 6 is inclined away from the side of the connecting pipe. For example, the shape of the connecting protrusion 6 can be trapezoidal. The long side of the trapezoid is connected to the rotating rod 5, and the short side of the trapezoid is inserted into the connecting groove. In this way, during the connection process between the connecting pipe and the circulating pump 4, the sealing ring is placed between the connecting pipe and the circulating pump 4. The rotating rod 5 is rotated so that the connecting protrusion 6 is initially inserted into the connecting groove. The clamp is tightened. As the clamp is tightened, the connecting protrusion 6 is continuously inserted into the connecting groove. The inclined side wall of the connecting protrusion 6 will continuously squeeze the side wall of the connecting groove, causing the circulating pump 4 to move towards the connecting pipe, thereby squeezing the sealing ring to form an effective sealing connection and improving the connection sealing between the connecting pipe and the circulating pump 4.

[0052] To further improve the sealing performance of the connection between the connecting pipeline and the circulating pump 4, the sealing ring is, for example, a rigid blade ring 7 and an elastic ring 8 that wraps around the rigid blade ring 7. The end face of the circulating pump 4 facing the connecting pipeline is provided with a groove corresponding to the position of the rigid blade ring 7. During the compression process of the sealing ring, the rigid blade ring 7 drives the elastic ring 8 to undergo elastic deformation and gradually enter the groove, thereby forming a multi-section sealing connection, further improving the sealing performance of the connection between the connecting pipeline and the circulating pump 4.

[0053] This invention also provides a method for treating coking wastewater, including an aerobic bacteria enrichment and acclimatization process and a micro-nano bubble-enhanced degradation process, using the aforementioned coking wastewater treatment device. The treatment method specifically includes the following steps:

[0054] Step 1: Enrich the mixed microbial community from the activated sludge, and acclimate the mixed microbial community so that it still has good growth and degradation ability under high concentration of phenol, and obtain the acclimatized seed liquid.

[0055] Step 2: Fill reactor 2 (e.g., a 4.6L plexiglass tank) with biofilm carrier (e.g., polyurethane sponge, activated carbon, porous ceramics, PE (polyethylene) filler or fiber filler). The amount of biofilm carrier is 25-35% of the total volume of reactor 2. Inoculate reactor 2 with acclimated seed liquid. The amount of acclimated seed liquid inoculated is 5-10% of the volume of the coking wastewater to be treated. Divide the coking wastewater to be treated into multiple portions. Add nutrients to at least one portion of the coking wastewater and inject it into reactor 2. Mixed microbial biofilm is formed on the biofilm carrier, and a yellow biofilm with aerobic bacteria uniformly attached to the surface is formed on the biofilm carrier.

[0056] Step 3: Connect the micro-nano bubble generator 3 into the reactor 2. Connect the air inlet of the micro-nano bubble generator 3 to the atmosphere. Connect the liquid inlet and the micro-nano bubble outlet of the micro-nano bubble generator 3 to the reactor 2 respectively. Introduce micro-nano bubbles into the reactor 2 to provide oxygen for the growth of aerobic bacteria. The air inlet flow rate of the micro-nano bubbles is 40-60 ml / min.

[0057] Step 4: Inject the remaining coking wastewater with different phenol concentrations (400-800 mg / L) into reactor 2. After degradation for 8-24 hours, open the drain valve at the bottom of reactor 2 to discharge the treated coking wastewater.

[0058] Compared with the prior art, the beneficial effects of the coking wastewater treatment method provided by the present invention are basically the same as those of the coking wastewater treatment device provided above, and will not be described in detail here.

[0059] Considering that a continuous supply of microbubbles might lead to excessively high temperatures within reactor 2, affecting the amount of microbubbles generated, microbubbles are intermittently introduced into reactor 2 in step 3. This is because intermittent introduction of microbubbles ensures that the coking wastewater does not flow continuously within the microbubble generator 3, thus avoiding the problem of reduced microbubble generation due to increased wastewater temperature. Simultaneously, it also maintains the activity of aerobic bacteria in the biofilm.

[0060] Considering the interaction between the phenol concentration in the coking wastewater and the air flow rate of the micro-nano bubble generator 3, as well as the bubble supply time and interval in each cycle, in order to further improve the treatment effect of the coking wastewater, micro-nano bubbles are introduced intermittently in stages according to the phenol concentration in the coking wastewater. Specifically, the relationship between the stages and the corresponding intermittent process parameters is as follows:

[0061] The phenol concentration is 700-800 mg / L, the air inlet flow rate of the micro-nano bubble generator 3 is 55-60 ml / min, and the bubble supply time in each cycle is 4-6 h with an interval of 1-2 h.

[0062] The phenol concentration is 500-700 mg / L, the air inlet flow rate of the micro-nano bubble generator 3 is 50-55 ml / min, and the bubble supply time in each cycle is 2-4 h, with an interval time of 2-4 h.

[0063] The phenol concentration is 400-500 mg / L, the air inlet flow rate of the micro-nano bubble generator 3 is 40-50 ml / min, and the bubble supply time in each cycle is 1-2 hours, with an interval of 1-2 hours.

[0064] To ensure the enrichment effect of the mixed microbial community, step 1 above includes the following steps:

[0065] Step 11: Take activated sludge and inoculate it into the enrichment medium (e.g., beef extract peptone enrichment medium), with the activated sludge accounting for 2% to 10% of the mass of the enrichment medium;

[0066] Step 12: Incubate at 25–35°C and 120–140 rpm in a shaking incubator until the bacterial cell concentration (OD) reaches a certain level. 600 The value reached 1.5;

[0067] Step 13: Inoculate the bacterial culture obtained in Step 12 into an inorganic salt medium at an inoculum volume of 4-6% and culture until OD. 600 Reached 1.0;

[0068] Step 14: Place the bacterial solution obtained in Step 13 in a refrigerator at 4°C for cold storage as seed solution to be domesticated.

[0069] Similarly, to ensure the acclimatization effect of the mixed microbial community, step 1 above includes the following steps:

[0070] Step 11': Inoculate the seed culture to be domesticated into an inorganic culture medium with a concentration of 200 mg / L phenol, and after domestication for 24-48 h, the first generation of domesticated seed culture is obtained;

[0071] Step 12': Take a portion (e.g., 10 ml) of the first-generation domesticated seed solution and inoculate it into an inorganic culture medium with a concentration of 400 mg / L phenol. After domestication for 24–48 h, the second-generation domesticated seed solution is obtained.

[0072] Step 13': Take a portion (e.g., 10 ml) of the second-generation domesticated seed solution and inoculate it into an inorganic culture medium with a concentration of 600 mg / L phenol. After domestication for 24–48 h, the third-generation domesticated seed solution is obtained.

[0073] Step 14': Take a portion (e.g., 10 ml) of the third-generation domesticated seed culture and inoculate it into an inorganic culture medium with a concentration of 800 mg / L phenol. After domestication for 24–48 h, store the bacterial culture in a refrigerator at 4 °C as the domesticated seed culture.

[0074] To ensure the effectiveness of the biofilm formation, step 2 above includes the following steps:

[0075] Step 21: Fill reactor 2 with a biofilm carrier;

[0076] Step 22: Inoculate the domesticated seed liquid into reactor 2;

[0077] Step 23: Add nutrients to the coking wastewater to be treated, adjust the pH of the coking wastewater containing nutrients to 6.5-7.5, divide the coking wastewater to be treated into multiple portions, each portion having a volume of 3-3.5L, take one portion of the coking wastewater to be treated, add nutrients, and inject it into reactor 2, aerate reactor 2, and react at room temperature for 36-72h;

[0078] Step 24: Maintain aeration and replace the existing coking wastewater containing nutrients in reactor 2 with another batch of coking wastewater containing nutrients. React at room temperature for 36-72 hours.

[0079] Step 25: Repeat step 24 at least 10 times (e.g., 10 to 15 times) for 20 to 30 days of incubation until a yellow biofilm with aerobic bacteria uniformly attached to the surface is formed on the biofilm carrier.

[0080] To further improve the biofilm formation effect and efficiency, the above aeration process adopts the following steps:

[0081] Step 231: Micro-nano bubble aeration is carried out on reactor 2. The micro-nano bubble aeration pressure is 0.3-0.6 MPa, the micro-nano bubble aeration inlet flow rate is 50-70 mL / min, and the micro-nano bubble aeration time is 1.5-2.5 h.

[0082] Step 232: Aerate reactor 2 with air at an air flow rate of 180-220 mL / min for 2.6-3.5 h.

[0083] Step 233: Repeat steps 231 and 232 until step 25 is completed.

[0084] Example 1

[0085] In this example, aerobic bacteria targeting phenol were selected from the activated sludge of the aerobic tank in the wastewater treatment plant of a chemical plant in Ningdong.

[0086] Specifically, the method for enhancing aerobic microbial treatment of coking wastewater using micro-nano bubbles includes the following steps:

[0087] Step a: Prepare beef extract peptone medium, which consists of 5 g / L beef extract, 10 g / L peptone and 5 g / L NaCl;

[0088] Step b: Activated sludge taken from the aerobic tank of a wastewater treatment plant in Ningdong was added to beef extract peptone medium at a dosage of 5% by mass and cultured in a constant temperature shaking incubator at 30℃ and 130 rpm until the bacterial cell concentration (OD) reached the target concentration. 600 The value reached 1.5;

[0089] Step c: Take the bacterial culture obtained in step b and inoculate it into beef extract peptone medium with the same formulation, repeating 4 times until there are no obvious activated sludge particles in the medium, and OD... 600 Reached 1.0;

[0090] Step d: Place the bacterial solution from the last culture medium in a refrigerator at 4°C for storage as a seed culture to be domesticated;

[0091] Step e: Prepare an inorganic salt culture medium for acclimatization, containing 100 mg / L ammonia nitrogen and 200 mg / L phenol. Inoculate the seed culture to be acclimatized into the inorganic salt culture medium and incubate it in a constant temperature shaking incubator at 30°C and 130 rpm until the phenol degradation rate reaches 70%. Then, transfer the bacterial culture in certain volumes sequentially to inorganic culture medium containing 400 mg / L phenol and 600 mg / L phenol to continue acclimatization until the aerobic bacteria exhibit good growth and degradation capabilities in an inorganic salt culture medium containing 800 mg / L phenol. Store this bacterial culture as the acclimatized seed culture. See [link to relevant documentation]. Figure 4 ;

[0092] Step g: Fill a 4.6L plexiglass container with 30% polyurethane sponge. Add the acclimated seed solution and the coking wastewater to be treated at a mass ratio of 1:15. The coking wastewater to be treated (per liter) contains nutrients including 400mg phenol, 1.388g sodium acetate (trihydrate), 0.432g ammonium sulfate, 0.5g KH2PO4, 0.3g Na2HPO4, 0.06g MgSO4, 0.01g FeSO4·7H2O, and 1g NaCl. React at room temperature for 48h, then replace the coking wastewater and continue the reaction for another 48h. Repeat this process 15 times. After 30 days of cultivation, until a uniformly attached yellow biofilm of aerobic bacteria forms on the surface of the polyurethane sponge. See [link to relevant documentation]. Figure 5 During this process, the reactor is aerated;

[0093] Step h: Inject one of the remaining portions of coking wastewater (3.5L) into the reactor, turn on the micro-nano bubble generator, adjust the pressure to 0.5MPa, the air intake to 60mL / min, and run the micro-nano aeration for 2 hours. Then turn off the micro-nano bubble generator, turn on the aerator, the air intake to 220mL / min, and run the normal aeration for 3 hours. Then run the micro-nano aeration for 2 hours, and the normal aeration for 3 hours. The total residence time is 10 hours.

[0094] Step i: Inject the remaining coking wastewater with a phenol content of 400 mg / L and a COD content of 1800 mg / L into the reactor. After degradation for 18 hours, open the drain valve at the bottom of the reactor to discharge the treated coking wastewater. The phenol degradation rate in the treated coking wastewater is 99.59%, and the COD degradation rate is 89.52%.

[0095] Comparative Example 1

[0096] The only difference between this comparative example and Example 1 is that the entire reactor system does not contain a micro-nano bubble generator. The entire reaction process is aerated by a regular air pump. The formulation of the coking wastewater, other steps, and corresponding process parameters remain the same.

[0097] It should be noted that this comparative example is only for comparing the effects of micro-nano bubbles and air aeration on the treatment effect, and does not indicate that the steps and process parameters of this comparative example belong to the prior art.

[0098] Tests showed that the phenol degradation rate was 58.24% and the COD degradation rate was 48.37%.

[0099] The comparison chart of phenol removal rates between Example 1 and Comparative Example 1 is shown below. Figure 6 ,from Figure 6It can be seen that the removal rate of phenol by using micro-nano bubbles is significantly higher than that by using air aeration.

[0100] Example 2

[0101] In this example, aerobic bacteria targeting phenol were selected from the activated sludge of the aerobic tank in the wastewater treatment plant of a chemical plant in Ningdong.

[0102] Specifically, the method for enhancing aerobic microbial treatment of coking wastewater using micro-nano bubbles includes the following steps:

[0103] Step a: Prepare beef extract peptone medium, which consists of 5 g / L beef extract, 10 g / L peptone and 5 g / L NaCl;

[0104] Step b: Activated sludge taken from the aerobic tank of a wastewater treatment plant in Ningdong was added to beef extract peptone medium at a dosage of 8% by mass and cultured in a constant temperature shaking incubator at 35°C and 120 rpm until the bacterial cell concentration (OD) reached the target concentration. 600 The value reached 1.5;

[0105] Step c: Take the bacterial culture obtained in step b and inoculate it into beef extract peptone medium with the same formulation, repeating 5 times until there are no obvious activated sludge particles in the medium, and OD... 600 Reached 1.0;

[0106] Step d: Place the bacterial solution from the last culture medium in a refrigerator at 4°C for storage as a seed culture to be domesticated;

[0107] Step e: Prepare an inorganic salt culture medium for acclimatization, with an ammonia nitrogen content of 100 mg / L and a phenol content of 200 mg / L. Inoculate the seed culture to be acclimatized into the inorganic salt culture medium and incubate it in a constant temperature shaking incubator at 25°C and 140 rpm for 24 h until the phenol degradation rate is 70%. Then, transfer a certain amount of the bacterial culture to inorganic culture medium containing 400 mg / L phenol and inorganic culture medium containing 600 mg / L phenol respectively and continue acclimatization for 48 h. Until the aerobic bacteria have good growth and degradation ability after acclimatization in inorganic salt culture medium containing 800 mg / L phenol for 36 h, store the bacterial culture in a refrigerator at 4°C and use the bacterial culture at this time as the acclimatized seed culture.

[0108] Step g: Fill a 4.6L plexiglass container with 35% polyurethane sponge. Add the acclimated seed solution and the coking wastewater to be treated to the plexiglass container at a mass ratio of 1:10. The coking wastewater to be treated (per liter) contains nutrients including 400mg phenol, 1.388g sodium acetate (trihydrate), 0.432g ammonium sulfate, 0.5g KH2PO4, 0.3g Na2HPO4, 0.06g MgSO4, 0.01g FeSO4·7H2O, and 1g NaCl. React at room temperature for 72h, then replace the coking wastewater to be treated and continue the reaction for 36h. Repeat 18 times. After 27 days of cultivation, until a uniform yellow biofilm of aerobic bacteria forms on the surface of the polyurethane sponge, the reactor is aerated during this process.

[0109] Step h: Inject one of the remaining portions of coking wastewater (3.5L) into the reactor, turn on the micro-nano bubble generator, adjust the pressure to 0.3MPa, the air intake to 70mL / min, and run the micro-nano aeration for 1.5 hours. Then turn off the micro-nano bubble generator, turn on the aerator, and run the air intake to 200mL / min for 2.5 hours of normal aeration, followed by another 1.5 hours of micro-nano aeration and another 2.5 hours of normal aeration, for a total retention time of 8 hours.

[0110] Step i: Inject the remaining coking wastewater with a phenol content of 400 mg / L and a COD content of 1800 mg / L into the reactor. After degradation for 24 hours, open the drain valve at the bottom of the reactor to discharge the treated coking wastewater. The phenol degradation rate in the treated coking wastewater is 99.0%, and the COD degradation rate is 90%.

[0111] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for treating coking wastewater, characterized in that, A coking wastewater treatment device is used, comprising a reactor, a micro / nano bubble generator, and a biofilm carrier. The biofilm carrier fills the reactor. The inlet of the micro / nano bubble generator is connected to the reactor, the outlet of the micro / nano bubble generator is connected to the reactor, and the air inlet of the micro / nano bubble generator is connected to the atmosphere. The treatment method includes the following steps: Step 1: Enriching mixed microbial communities from activated sludge and acclimating the mixed microbial communities to obtain acclimated seed liquid; Step 2: Filling the reactor with the biofilm carrier, inoculating the reactor with the acclimated seed liquid, dividing the coking wastewater to be treated into multiple portions, adding nutrients to at least one portion of the coking wastewater and injecting it into the reactor, and inoculating the reactor with the acclimated seed liquid to allow the mixed microbial communities to form a biofilm on the biofilm carrier; Step 3: Introducing micro / nano bubbles into the reactor; Step 4: Adding nutrients to the remaining coking wastewater and injecting it into the reactor for degradation, thus completing the treatment of the coking wastewater. In step 2, the biofilm formation includes the following steps: Step 21: Fill the reactor with a biofilm carrier; Step 22: Inoculate the reactor with the acclimated seed solution; Step 23: Divide the coking wastewater to be treated into multiple portions, add nutrients to at least one portion of the coking wastewater and inject it into the reactor, and inoculate the reactor with the acclimated seed solution, aerating and reacting the reactor; Step 24: Maintaining aeration, replace the existing coking wastewater containing nutrients in the reactor with another portion of coking wastewater containing nutrients, and react; Step 25: Repeat step 24 until a biofilm with aerobic bacteria attached to its surface is formed on the biofilm carrier; When the phenol concentration is 700-800 mg / L, the air inlet flow rate of the micro-nano bubble generator is 55-60 ml / min, and the bubble supply time in each cycle is 4-6 hours with an interval of 1-2 hours; when the phenol concentration is 500-700 mg / L, the air inlet flow rate of the micro-nano bubble generator is 50-55 ml / min, and the bubble supply time in each cycle is 2-4 hours with an interval of 2-4 hours; when the phenol concentration is 400-500 mg / L, the air inlet flow rate of the micro-nano bubble generator is 40-50 ml / min, and the bubble supply time in each cycle is 1-2 hours with an interval of 1-2 hours. The aeration includes the following steps: Step 231: aerating the reactor with micro-nano bubbles; Step 232: aerating the reactor with air; Step 233: repeating steps 231 and 232 until step 25 is completed. A circulating pump is located between the liquid inlet of the micro-nano bubble generator and the reactor, and the circulating pump is sealed to the connecting pipeline through a sealing connector. The sealing connector includes a sealing ring, a clamp, and multiple rotating rods. The sealing ring is located at the end of the connecting pipe. The multiple rotating rods are connected to each other by the clamp to form a whole. The pivot end of the rotating rod is rotatably connected to the outer wall of the connecting pipe. The connecting end of the rotating rod is provided with a connecting protrusion facing the circulation pump. The circulation pump is provided with a connecting groove corresponding to the position of the connecting protrusion. Along the direction gradually away from the rotating rod, the connecting protrusion is inclined towards the side of the connecting pipe away from the connecting pipe. The shape of the connecting protrusion is trapezoidal. The long side of the trapezoid is connected to the rotating rod, and the short side of the trapezoid is inserted into the connecting groove. The sealing ring includes a rigid blade ring and an elastic ring that wraps around the rigid blade ring. The end face of the circulating pump facing the connecting pipeline is provided with a groove corresponding to the position of the rigid blade ring. During the compression process of the sealing ring, the rigid blade ring drives the elastic ring to undergo elastic deformation and gradually enter the groove to form a multi-section sealing connection.

2. The method for treating coking wastewater according to claim 1, characterized in that, The micro-nano bubble generator has its micro-nano bubble outlet located at the bottom of the reactor.

3. The method for treating coking wastewater according to claim 1, characterized in that, A filter screen is provided at the outlet of the reactor connected to the circulating pump, on the connecting pipeline between the circulating pump and the reactor, and / or at the inlet of the circulating pump.

4. The method for treating coking wastewater according to claim 1, characterized in that, In step 23, after adding nutrients to the coking wastewater to be treated and before dividing the nutrient-containing coking wastewater into multiple portions, the following steps are also included: Adjust the pH of the coking wastewater containing nutrients to 6.5~7.

5.

5. The method for treating coking wastewater according to claim 1, characterized in that, The micro-nano bubble aeration pressure is 0.3~0.6MPa, the micro-nano bubble aeration inlet flow rate is 50~70mL / min, and the micro-nano bubble aeration time is 1.5~2.5h.

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