A method for treating coking wastewater by using micro-nano bubbles to enhance aerobic bacteria

Abstract

The present invention discloses a method for treating coking wastewater by strengthening aerobic bacteria with micro-nano bubbles, which 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. The method comprises: enriching a mixed bacterial community from activated sludge and taming the mixed bacterial community; filling a biofilm carrier in a reactor, 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 tamed seed liquid into the reactor, and forming a biofilm of the mixed bacterial community on the biofilm carrier; introducing micro-nano bubbles into the reactor; and adding nutrients to the remaining coking wastewater and injecting it into the reactor for degradation. The method can be used for the treatment of coking wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial organic wastewater treatment, and in particular relates to a method for treating coking wastewater by using micro-nano bubbles to enhance aerobic bacteria. Background Art

[0002] The pollutants in coking wastewater are of various types and complex composition, including phenols, polycyclic aromatic hydrocarbons, heterocyclic compounds, sulfides, cyanides and other toxic substances. In the actual production process, high concentrations of organic matter are the hot spots and difficulties in the treatment of this type of wastewater.

[0003] Since coking wastewater contains many biological inhibitory substances and substances that are difficult to be treated biologically, the traditional aerobic coking wastewater treatment device usually includes an air supply unit 1 and a reactor 2. Figure 1 The gas supply unit 1 supplies oxygen into the reactor 2 to provide oxygen for aerobic bacteria. 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] In view of the above analysis, the present invention aims to provide a method for treating coking wastewater by using micro-nano bubbles to enhance aerobic bacteria, 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 purpose of the present invention is mainly achieved through the following technical solutions:

[0006] The present invention provides a method for treating coking wastewater by using micro-nano bubbles to enhance aerobic microorganisms, comprising the following steps:

[0007] Step 1: enriching a mixed bacterial community from activated sludge, domesticating the mixed bacterial community, and obtaining domesticated seed liquid;

[0008] Step 2: Filling the biofilm carrier in the reactor, 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, inoculating the acclimated seed liquid into the reactor, and forming a mixed bacterial colony biofilm on the biofilm carrier;

[0009] Step 3: introducing micro-nano bubbles into the reactor;

[0010] Step 4: Add nutrients to the remaining coking wastewater and inject it into the reactor for degradation to complete the treatment of the coking wastewater.

[0011] Furthermore, in step 2, the filling amount of the biofilm carrier is 25-35% of the total volume of the reactor.

[0012] Furthermore, in step 2, the volume percentage of the domesticated seed liquid inoculation to the coking wastewater to be treated is 5-10%.

[0013] Furthermore, in step 3, the air intake flow rate of the micro-nano bubbles is 40 to 60 ml / min.

[0014] Furthermore, in step 4, the degradation time is 8 to 24 hours.

[0015] Furthermore, in step 3, micro-nano bubbles are intermittently introduced into the reactor.

[0016] Furthermore, the phenol concentration in the coking wastewater is 700-800 mg / L, the air intake flow rate of the micro-nano bubbles is 55-60 ml / min, and the bubble supply time is 4-6 hours and the intermittent time is 1-2 hours in each cycle; the phenol concentration is 500-700 mg / L, the air intake flow rate of the micro-nano bubbles is 50-55 ml / min, and the bubble supply time is 2-4 hours and the intermittent time is 2-4 hours in each cycle; the phenol concentration is 400-500 mg / L, the air intake flow rate of the micro-nano bubbles is 40-50 ml / min, and the bubble supply time is 1-2 hours and the intermittent time is 1-2 hours in each cycle.

[0017] Further, in step 1, the enrichment comprises the following steps:

[0018] Step 11: taking activated sludge and inoculating it into enrichment medium;

[0019] Step 12: Cultivate at a constant temperature until the bacterial concentration reaches 1.5;

[0020] Step 13: Inoculate the bacterial solution obtained in step 12 into the inorganic salt medium and culture until the OD 600 Reach 1.0;

[0021] Step 14: Refrigerate the bacterial solution obtained in step 13 as the seed solution to be domesticated.

[0022] Furthermore, in step 1, domestication includes the following steps:

[0023] Step 11': inoculating the seed solution to be domesticated into an inorganic culture medium to obtain the first generation domesticated seed solution after domestication;

[0024] Step 12': taking part of the first generation domesticated seed solution and inoculating it into an inorganic culture medium to obtain the second generation domesticated seed solution after domestication;

[0025] Step 13': taking part of the second generation domesticated seed solution and inoculating it into an inorganic culture medium, and obtaining the third generation domesticated seed solution after domestication;

[0026] Step 14': Take part of the third generation domesticated seed solution and inoculate it into an inorganic culture medium, and store it in a refrigerator after domestication to serve as the domesticated seed solution.

[0027] Furthermore, the phenol concentration in the inorganic culture medium in step 11 ' is less than the phenol concentration in the inorganic culture medium in step 12' and less than the phenol concentration in the inorganic culture medium in step 13' and less than the phenol concentration in the inorganic culture medium in step 14'.

[0028] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0029] A) The method for treating coking wastewater with micro-nano bubbles enhanced by aerobic microorganisms provided by the present invention uses air micro-nano bubbles to replace the traditional aeration method to oxygenate the reactor. The micro-nano bubbles can exist in the reactor for a long time without bursting, thereby greatly improving the mass transfer efficiency of oxygen.

[0030] B) In the method for treating coking wastewater with micro-nano bubbles enhanced by aerobic microorganisms provided by the present invention, a biofilm carrier for biofilm formation is provided in the reactor, and the aerobic bacteria grow on the biofilm carrier, and basically no sludge is generated, so there is no need to set a stirring device in the reactor. While achieving the effect of oxygen supply, the inactivation of aerobic bacteria due to shear force and mechanical force caused by stirring can be effectively avoided; and because the aerobic bacteria are solidified on the biofilm carrier, they will not enter the micro-nano bubble generator, thereby preventing the aerobic bacteria from being subjected to high pressure and high impact force in the micro-nano bubble generator.

[0031] Other features and advantages of the present invention will be described in the following description, and part of them will become obvious from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0033] Figure 1 It is a structural schematic diagram of an air aeration reactor in the prior art;

[0034] Figure 2 A schematic diagram of the structure of a treatment device in the method for treating coking wastewater by using micro-nano bubbles to enhance aerobic microorganisms provided by the present invention;

[0035] Figure 3 A schematic diagram of the structure of a sealing connector in the method for treating coking wastewater with micro-nano bubbles enhanced by aerobic microorganisms provided by the present invention;

[0036] Figure 4 This is a suspension diagram of the seed solution after domestication in Example 1 of the present invention;

[0037] Figure 5This is a picture of the polyurethane sponge after film formation in Example 1 of the present invention;

[0038] Figure 6 It is a comparison chart of phenol removal rates of Example 1 of the present invention and Comparative Example 1.

[0039] Reference numerals:

[0040] 1-gas supply unit; 2-reactor; 3-micro-nano bubble generator; 4-circulation pump; 5-rotating rod; 6-connecting protrusion; 7-rigid blade ring; 8-elastic ring. DETAILED DESCRIPTION

[0041] Preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used to explain the principles of the present invention together with the embodiments of the present invention.

[0042] Micro-nano bubbles are tiny bubbles with diameters between the micro-nano level. They have the advantages of long residence time in water, high mass transfer efficiency, high Zeta potential, etc., and are widely used in aquaculture, crop growth, sewage treatment, etc. The present invention provides oxygen to aerobic bacteria through air micro-nano bubbles, promotes the growth of aerobic bacteria and the degradation of organic pollutants.

[0043] The present invention provides a method for treating coking wastewater by using micro-nano bubbles to enhance aerobic microorganisms. Figures 2 to 3 , including the enrichment and domestication process of aerobic bacteria and the micro-nano bubble enhanced degradation process, specifically including the following steps:

[0044] Step 1: enriching a mixed bacterial community from activated sludge, domesticating the mixed bacterial community so that the mixed bacterial community still has good growth and degradation capabilities under high concentrations of phenol, and obtaining domesticated seed liquid;

[0045] Step 2: Filling a biofilm carrier (e.g., polyurethane sponge, activated carbon, porous ceramic, PE (polyethylene) filler or fiber filler) in a reactor 2 (e.g., a 4.6L organic glass barrel), wherein the filling amount of the biofilm carrier is 25-35% of the total volume of the reactor 2, inoculating the tamed seed liquid into the reactor 2, wherein the inoculation amount of the tamed seed liquid accounts for 5-10% of the volume percentage of the coking wastewater to be treated, dividing the coking wastewater to be treated into a plurality of portions, adding nutrients to at least one portion of the coking wastewater and then injecting it into the reactor 2, forming a mixed bacterial community biofilm on the biofilm carrier, and forming a yellow biofilm with aerobic bacteria evenly attached to the surface on the biofilm carrier;

[0046] Step 3: Connect the micro-nano bubble generator 3 to 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, and the air inlet flow rate of the micro-nano bubbles is 40-60 ml / min;

[0047] Step 4: Add nutrients to the remaining coking wastewater with different phenol concentrations (400-800 mg / L) and inject it into the reactor 2. After degradation for 8-24 hours, open the drain valve at the lower end of the reactor 2 to discharge the treated coking wastewater.

[0048] The conventional aeration method generates relatively large bubbles, which rise rapidly, gradually grow larger, and then burst, resulting in the restriction of oxygen mass transfer. Compared with the prior art, the method for treating coking wastewater with micro-nano bubbles enhanced by aerobic microorganisms provided by the present invention uses air micro-nano bubbles instead of conventional aeration methods to oxygenate the reactor 2, and the micro-nano bubbles can exist in the reactor 2 for a long time without bursting, thereby greatly improving the oxygen mass transfer efficiency.

[0049] At the same time, in the prior art, no solidification device is provided in the reactor 2, and the aerobic bacteria are in a free state in the reactor 2, resulting in a large amount of sludge being generated during the treatment of the coking wastewater, so that the aerobic bacteria at the bottom of the sludge cannot contact with oxygen and cannot survive, so it is often necessary to set a stirring device in the reactor in the prior art. In the method of micro-nano bubble enhanced aerobic microorganism treatment of coking wastewater of the present invention, a biofilm carrier for biofilm is provided in the reactor 2, and the aerobic bacteria grow on the biofilm carrier, and basically no sludge is generated, so there is no need to set a stirring device in the 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; and, because the aerobic bacteria are solidified on the biofilm carrier, they will not enter the micro-nano bubble generator 3, so that the aerobic bacteria can be prevented from being subjected to high pressure and high impact in the micro-nano bubble generator 3.

[0050] Considering that the uninterrupted supply of micro-nano bubbles may cause the temperature in the reactor 2 to be too high, affecting the amount of micro-nano bubbles generated, in the above step 3, micro-nano bubbles are intermittently introduced into the reactor 2. This is because the intermittent introduction of micro-nano bubbles can ensure that the coking wastewater does not flow in the micro-nano bubble generator 3 for a long time, thereby avoiding the problem of a decrease in the number of micro-nano bubbles generated due to the increase in the temperature of the coking wastewater, and at the same time, it can also maintain the activity of aerobic bacteria in the biofilm.

[0051] Considering that the phenol concentration in the coking wastewater interacts with the air intake flow rate of the micro-nano bubble generator 3, the bubble supply time in each cycle and the intermittent time, in order to further improve the treatment effect of the coking wastewater, micro-nano bubbles are intermittently introduced according to the phenol concentration classification in the coking wastewater. Specifically, the corresponding relationship between the classification and the corresponding intermittent process parameters is as follows:

[0052] The phenol concentration is 700-800 mg / L, the air flow rate of the micro-nano bubble generator 3 is 55-60 ml / min, and in each cycle, the bubble supply time is 4-6 hours, and the intermittent time is 1-2 hours;

[0053] The phenol concentration is 500-700 mg / L, the air flow rate of the micro-nano bubble generator 3 is 50-55 ml / min, and in each cycle, the bubble supply time is 2-4 hours, and the intermittent time is 2-4 hours;

[0054] The phenol concentration is 400-500 mg / L, the air intake flow rate of the micro-nano bubble generator 3 is 40-50 ml / min, and in each cycle, the bubble supply time is 1-2 hours and the intermittent time is 1-2 hours.

[0055] In order to ensure the enrichment effect of the mixed flora, in the above step 1, the enrichment includes the following steps:

[0056] Step 11: taking activated sludge and inoculating it into an enrichment medium (for example, beef extract peptone enrichment medium), wherein the activated sludge accounts for 2% to 10% of the mass percentage of the enrichment medium;

[0057] Step 12: Cultivate in a shaker at 25-35°C and 120-140 rpm until the bacterial concentration (OD 600 ) reaches 1.5;

[0058] Step 13: Inoculate the bacterial solution obtained in step 12 into the inorganic salt medium at an inoculum volume of 4-6% and culture until the OD 600 Reach 1.0;

[0059] Step 14: The bacterial solution obtained in step 13 is placed in a refrigerator at 4°C and stored as the seed solution to be domesticated.

[0060] Similarly, in order to ensure the domestication effect of the mixed flora, in the above step 1, domestication includes the following steps:

[0061] Step 11': inoculating the seed solution to be domesticated into an inorganic culture medium with a concentration of 200 mg / L phenol, and after domestication for 24 to 48 hours, obtaining the first generation domesticated seed solution;

[0062] Step 12': taking a portion (e.g., 10 ml) of the first generation domesticated seed solution and inoculating it into an inorganic culture medium with a concentration of 400 mg / L phenol, and after domestication for 24 to 48 hours, obtaining the second generation domesticated seed solution;

[0063] Step 13': taking a portion (e.g., 10 ml) of the second generation domesticated seed solution and inoculating it into an inorganic culture medium with a concentration of 600 mg / L phenol, and after domestication for 24 to 48 hours, obtaining the third generation domesticated seed solution;

[0064] Step 14': Take a portion (eg, 10 ml) of the third generation domesticated seed solution and inoculate it into an inorganic culture medium containing 800 mg / L phenol. After domestication for 24 to 48 hours, store the bacterial solution in a refrigerator at 4°C as the domesticated seed solution.

[0065] In order to ensure the biofilm effect, in the above step 2, the biofilm formation includes the following steps:

[0066] Step 21: Filling the biofilm carrier into the reactor 2;

[0067] Step 22: inoculating the domesticated seed solution into the reactor 2;

[0068] Step 23: adding nutrients to the coking wastewater to be treated, adjusting the pH of the coking wastewater to be treated containing the nutrients to 6.5-7.5, dividing the coking wastewater to be treated into a plurality of portions, wherein the volume of each portion of the coking wastewater to be treated is 3-3.5 L, taking one portion of the coking wastewater to be treated, adding the nutrients, and injecting it into the reactor 2, aerating the reactor 2, and reacting at room temperature for 36-72 hours;

[0069] Step 24: maintaining the aeration state, replacing the existing coking wastewater containing nutrients to be treated in the reactor 2 with another portion of coking wastewater containing nutrients to be treated, and reacting at room temperature for 36 to 72 hours;

[0070] Step 25: Repeat step 24 at least 10 times (for example, 10 to 15 times) and cultivate for 20 to 30 days until a yellow biofilm with aerobic bacteria evenly attached to the surface is formed on the biofilm carrier.

[0071] In order to further improve the biofilm formation effect and biofilm formation efficiency, the above aeration adopts the following steps:

[0072] Step 231: performing micro-nano bubble aeration on the reactor 2, wherein the micro-nano bubble aeration pressure is 0.3-0.6 MPa, the micro-nano bubble aeration air flow rate is 50-70 mL / min, and the micro-nano bubble aeration time is 1.5-2.5 h;

[0073] Step 232: aerating the reactor 2 with air, wherein the air aeration flow rate is 180 to 220 mL / min, and the air aeration time is 2.6 to 3.5 h;

[0074] Step 233: Repeat steps 231 and 232 until step 25 is completed.

[0075] Exemplarily, the above-mentioned method for treating coking wastewater by micro-nano bubble-enhanced aerobic microorganisms adopts a device with the following structure:

[0076] See also Figure 2 The device includes a reactor 2, a micro-nano bubble generator 3 and a circulation pump 4, the liquid inlet of the micro-nano bubble generator 3 is connected to the reactor 2 through the circulation pump 4, the micro-nano bubble outlet of the micro-nano bubble generator 3 is connected to the reactor 2, and the air inlet of the micro-nano bubble generator 3 is connected to the atmosphere.

[0077] In order to further increase the residence time of the nanobubbles in the reactor 2 , the micro-nano bubble outlet of the micro-nano bubble generator 3 is located at the bottom of the reactor 2 .

[0078] In order to prevent solids in the coking wastewater to be treated from clogging the microcirculation pump 4 and / or the nanobubble generator, a filter is provided at the liquid outlet connecting the reactor 2 and the circulation pump 4, on the connecting pipeline between the circulation pump 4 and the reactor 2, and / or at the liquid inlet of the circulation pump 4. The filter can effectively filter and treat the solids in the coking wastewater.

[0079] It can be understood that the circulation pump 4 and the connecting pipeline involve the flow of the coking wastewater to be treated, so the two can be sealed and connected via a sealing connector.

[0080] For example, see Figure 3The sealing connection comprises a sealing ring, a clamp and a plurality of rotating rods 5. The sealing ring is arranged at the end of the connecting pipeline. The plurality of rotating rods 5 are connected to each other through the clamp to form a whole. One end of the rotating rod 5 is defined as a pivot end, and the other end is defined as a connecting end. The pivot end of the rotating rod 5 is rotatably connected to the outer wall of the connecting pipeline. The connecting end of the rotating rod 5 is provided with a connecting protrusion 6 facing the circulating pump 4. The circulating 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 toward the side of the connecting pipeline away from the connecting pipeline. Exemplarily, the shape of the connecting protrusion 6 can be a trapezoid. 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 pipeline and the circulating pump 4, the sealing ring is placed between the connecting pipeline and the circulating pump 4, the rotating rod 5 is rotated so that the connecting protrusion 6 is initially inserted into the connecting groove, and the clamp is tightened. As the clamp is continuously tightened, the connecting protrusion 6 is continuously inserted into the connecting groove, and the inclined side walls of the connecting protrusion 6 will continuously squeeze the side walls of the connecting groove, so that the circulating pump 4 moves toward the direction of the connecting pipeline, thereby squeezing the sealing ring to form an effective sealing connection, thereby improving the connection sealing between the connecting pipeline and the circulating pump 4.

[0081] In order to further improve the sealing performance of the connection between the connecting pipeline and the circulation pump 4, as for the structure of the sealing ring, exemplarily, the sealing ring includes a rigid blade ring 7 and an elastic ring 8 wrapping the rigid blade ring 7, and the end face of the circulation pump 4 facing the connecting pipeline is provided with a blade groove corresponding to the position of the rigid blade ring 7. During the extrusion process of the sealing ring, the rigid blade ring 7 will drive the elastic ring 8 to undergo elastic deformation and gradually enter the blade groove, thereby forming a multi-section sealing connection, further improving the sealing performance of the connection between the connecting pipeline and the circulation pump 4.

[0082] Example 1

[0083] In this example, aerobic bacteria targeting phenol were enriched from the activated sludge in the aerobic tank of the sewage treatment plant in Ningdong.

[0084] Specifically, the method for treating coking wastewater by micro-nano bubble-enhanced aerobic microorganisms comprises the following steps:

[0085] Step a: preparing a beef extract peptone medium, the ingredients of which include 5 g / L beef extract, 10 g / L peptone and 5 g / L NaCl;

[0086] Step b: Add 5% by mass of activated sludge from a wastewater treatment aerobic tank of a coal chemical plant in Ningdong to beef extract peptone medium, and culture in a constant temperature shaking box at 30°C and 130rpm until the bacterial concentration (OD 600 ) reaches 1.5;

[0087] Step c: Take the culture medium obtained in step b and inoculate it into beef extract peptone culture medium of the same formula for 4 times until there are no obvious activated sludge particles in the culture medium and the OD 600 Reach 1.0;

[0088] Step d: The bacterial solution in the last culture medium is placed in a refrigerator at 4°C and stored as the seed solution to be domesticated;

[0089] Step e: prepare an inorganic salt culture medium for acclimation, wherein the ammonia nitrogen content is 100 mg / L and the phenol content is 200 mg / L, inoculate the seed solution to be acclimated into the inorganic salt culture medium, place it in a constant temperature oscillating box and culture it at 30°C and 130 rpm until the phenol degradation rate reaches 70%, transfer a certain amount of the bacterial solution to an inorganic culture medium containing 400 mg / L phenol and an inorganic culture medium containing 600 mg / L phenol in turn to continue acclimation until the aerobic bacteria have good growth and degradation capabilities in the inorganic salt culture medium containing 800 mg / L phenol, and save the bacterial solution at this time as the seed solution after acclimation, see Figure 4 ;

[0090] Step g: Fill a 4.6L organic glass barrel with 30% polyurethane sponge, put the acclimated seed liquid and the coking wastewater to be treated into the organic glass barrel at a mass ratio of 1:15, and the coking wastewater to be treated containing nutrients (per liter) includes 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 to be treated and continue to react for 48h, repeat 15 times, and after 30 days of cultivation, until a yellow biofilm formed by aerobic bacteria evenly attached to the surface of the polyurethane sponge is formed, see Figure 5 , during which the reactor is aerated;

[0091] Step h: inject the remaining portion of the coking wastewater (3.5 L) into the reactor, turn on the micro-nano bubble generator, adjust the pressure to 0.5 MPa, the air intake to 60 mL / min, operate in micro-nano aeration for 2 hours, turn off the micro-nano bubble generator, turn on the aerator, the air intake flow rate is 220 mL / min, normal aeration for 3 hours, then micro-nano aeration for 2 hours, normal aeration for 3 hours, and a total residence time of 10 hours;

[0092] Step i: inject the remaining coking wastewater with a phenol content of 400 and a COD content of 1800 mg / L into the reactor. After degradation for 18 hours, open the drain valve at the lower end 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%.

[0093] Comparative Example 1

[0094] The treatment process of this comparative example is different from that of Example 1 only in that the entire reactor system does not contain a micro-nano bubble generator, the entire reaction process is aerated by an ordinary air pump, and the formula of the coking wastewater, other steps and corresponding process parameters remain consistent.

[0095] 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 it cannot be said that the steps and process parameters of this comparative example belong to the prior art.

[0096] The results showed that the degradation rate of phenol was 58.24% and the degradation rate of COD was 48.37%.

[0097] See the comparison chart of phenol removal rate of Example 1 and Comparative Example 1. Figure 6 ,from Figure 6 It can be seen that the removal rate of phenol by using micro-nano bubbles is significantly higher than that by using air aeration.

[0098] Example 2

[0099] In this example, aerobic bacteria targeting phenol were enriched from the activated sludge in the aerobic tank of the sewage treatment plant in Ningdong.

[0100] Specifically, the method for treating coking wastewater by micro-nano bubble-enhanced aerobic microorganisms comprises the following steps:

[0101] Step a: preparing a beef extract peptone medium, the ingredients of which include 5 g / L beef extract, 10 g / L peptone and 5 g / L NaCl;

[0102] Step b: Add 8% by mass of activated sludge from a wastewater treatment aerobic tank of a coal chemical plant in Ningdong to beef extract peptone medium, and culture in a constant temperature shaking box at 35°C and 120rpm until the bacterial concentration (OD 600 ) reaches 1.5;

[0103] Step c: Take the culture medium obtained in step b and inoculate it into beef extract peptone culture medium of the same formula for 5 times until there are no obvious activated sludge particles in the culture medium and the OD 600 Reach 1.0;

[0104] Step d: The bacterial solution in the last culture medium is placed in a refrigerator at 4°C and stored as the seed solution to be domesticated;

[0105] Step e: preparing an inorganic salt culture medium for acclimation, wherein the ammonia nitrogen content is 100 mg / L and the phenol content is 200 mg / L, inoculating the seed solution to be acclimated into the inorganic salt culture medium, placing it in a constant temperature oscillating box for culturing at 25° C. and 140 rpm, and acclimating it for 24 hours until the phenol degradation rate is 70%, transferring a certain amount of the bacterial solution to an inorganic culture medium containing 400 mg / L phenol and an inorganic culture medium containing 600 mg / L phenol in sequence, and continuing to acclimate for 48 hours respectively, until the aerobic bacteria have good growth and degradation capabilities after acclimation in the inorganic salt culture medium containing 800 mg / L phenol for 36 hours, and storing the bacterial solution in a refrigerator at 4° C., and storing the bacterial solution at this time as the seed solution after acclimation;

[0106] Step g: filling a 4.6L organic glass barrel with 35% polyurethane sponge, putting the acclimated seed liquid and the coking wastewater to be treated in a mass ratio of 1:10 into the organic glass barrel, and the coking wastewater to be treated containing nutrients (per liter) includes 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, reacting at room temperature for 72h, then replacing the coking wastewater to be treated and continuing to react for 36h, repeating 18 times, and after 27 days of cultivation, until a yellow biofilm formed by aerobic bacteria evenly attached to the surface of the polyurethane sponge is formed, and the reactor is aerated during this process;

[0107] Step h: inject the remaining portion of coking wastewater (3.5 L) into the reactor, turn on the micro-nano bubble generator, adjust the pressure to 0.3 MPa, the air intake to 70 mL / min, operate in micro-nano aeration for 1.5 hours, turn off the micro-nano bubble generator, turn on the aerator, the air intake flow rate is 200 mL / min, normal aeration for 2.5 hours, then micro-nano aeration for 1.5 hours, normal aeration for 2.5 hours, and a total residence time of 8 hours;

[0108] Step i: inject the remaining coking wastewater with a phenol content of 400 and a COD content of 1800 mg / L into the reactor. After degradation for 24 hours, open the drain valve at the lower end 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%.

[0109] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for treating coking wastewater by using micro-nano bubbles to enhance aerobic microorganisms, characterized in that: The steps include: Step 1: enriching a mixed bacterial community from activated sludge, domesticating the mixed bacterial community, and obtaining domesticated seed liquid; Step 2: Filling the biofilm carrier in the reactor, 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, inoculating the acclimated seed liquid into the reactor, and forming a biofilm with a mixed bacterial community on the biofilm carrier; Step 3: introducing micro-nano bubbles into the reactor; Step 4: Add nutrients to the remaining coking wastewater and inject it into the reactor for degradation, thereby completing the treatment of the coking wastewater; The device used in the method includes a reactor, a micro-nano bubble generator and a circulation pump, wherein the liquid inlet of the micro-nano bubble generator is connected to the reactor through the circulation pump, 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; The circulation pump and the connecting pipeline between the circulation pump and the reactor are sealed and connected via a sealing connector; The sealing connection member comprises a sealing ring, a clamp and a plurality of rotating rods, the sealing ring being arranged at the end of the connecting pipeline, the plurality of rotating rods being connected to each other through the clamp to form a whole, the pivot end of the rotating rod being rotatably connected to the outer wall of the connecting pipeline, the connecting end of the rotating rod being provided with a connecting protrusion facing the circulation pump, the circulating pump being provided with a connecting groove corresponding to the position of the connecting protrusion, and along the direction gradually away from the rotating rod, the connecting protrusion is inclined towards the side of the connecting pipeline away from the connecting pipeline in the direction gradually away from the rotating rod, the shape of the connecting protrusion is a trapezoid, 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; in the process of connecting the connecting pipeline and the circulating pump, the sealing ring is placed between the connecting pipeline and the circulating pump, the rotating rod is rotated so that the connecting protrusion is initially inserted into the connecting groove, the clamp is tightened, the connecting protrusion is inserted into the connecting groove, the inclined side wall of the connecting protrusion squeezes the side wall of the connecting groove so that the circulating pump moves toward the connecting pipeline; The sealing ring includes a rigid blade ring and an elastic ring wrapping the rigid blade ring. The end surface of the circulating pump facing the connecting pipeline is provided with a blade groove corresponding to the position of the rigid blade ring. During the extrusion process of the sealing ring, the rigid blade ring drives the elastic ring to gradually enter the blade groove to form a multi-section sealing connection. In step 1, the enrichment comprises the following steps: Step 11: taking activated sludge and inoculating it into enrichment medium; Step 12: Cultivate at a constant temperature until the bacterial concentration reaches 1.5; Step 13: Inoculate the bacterial solution obtained in step 12 into the inorganic salt medium and culture until the OD 600 Reach 1.0; Step 14: refrigerate the bacterial solution obtained in step 13 as the seed solution to be domesticated; In step 2, the biofilm formation comprises the following steps: Step 21: Filling the biofilm carrier into the reactor; Step 22: inoculating the domesticated seed solution into the reactor; Step 23: adding nutrients to the coking wastewater to be treated, dividing the coking wastewater to be treated into multiple portions, taking one portion of the coking wastewater to be treated, adding nutrients, and injecting it into the reactor, aerating the reactor, and reacting; Step 24: maintaining the aeration state, using another portion of the coking wastewater to be treated containing nutrients to replace the existing coking wastewater to be treated containing nutrients in the reactor, and reacting; Step 25: Repeat step 24 at least 10 times, and culture until a yellow biofilm with aerobic bacteria evenly attached to the surface is formed on the biofilm carrier; The aeration adopts the following steps: Step 231: performing micro-nano bubble aeration on the reactor; Step 232: aerating the reactor with air; Step 233: Repeat steps 231 and 232 until step 25 is completed.

2. The method for treating coking wastewater by using micro-nano bubbles to enhance aerobic microorganisms according to claim 1, characterized in that: In the step 2, the filling amount of the biofilm carrier is 25-35% of the total volume of the reactor.

3. The method for treating coking wastewater by micro-nano bubble-enhanced aerobic microorganisms according to claim 1, characterized in that: In the step 2, the volume percentage of the seed liquid after acclimation to the coking wastewater to be treated is 5-10%.

4. The method for treating coking wastewater by micro-nano bubble-enhanced aerobic microorganisms according to claim 1, characterized in that: In step 3, the air intake flow rate of the micro-nano bubbles is 40 to 60 ml / min.

5. The method for treating coking wastewater by using micro-nano bubbles to enhance aerobic microorganisms according to claim 1, characterized in that: In step 4, the degradation time is 8 to 24 hours.

6. The method for treating coking wastewater by using micro-nano bubbles to enhance aerobic microorganisms according to claim 1, characterized in that: In the step 3, micro-nano bubbles are intermittently introduced into the reactor.

7. The method for treating coking wastewater by using micro-nano bubbles to enhance aerobic microorganisms according to claim 6, characterized in that: The phenol concentration in the coking wastewater is 700-800 mg / L, the air intake flow rate of the micro-nano bubbles is 55-60 ml / min, and in each cycle, the bubble supply time is 4-6 hours, and the intermittent time is 1-2 hours; The phenol concentration is 500-700 mg / L, the air flow rate of the micro-nano bubbles is 50-55 ml / min, and in each cycle, the bubble supply time is 2-4 hours, and the intermittent time is 2-4 hours; The phenol concentration is 400-500 mg / L, the air intake flow rate of the micro-nano bubbles is 40-50 ml / min, and in each cycle, the bubble supply time is 1-2 hours and the intermittent time is 1-2 hours.

8. The method for treating coking wastewater by using micro-nano bubbles to enhance aerobic microorganisms according to any one of claims 1 to 7, characterized in that: In step 1, the domestication comprises the following steps: Step 11': inoculating the seed solution to be domesticated into an inorganic culture medium to obtain the first generation domesticated seed solution after domestication; Step 12': taking part of the first generation domesticated seed solution and inoculating it into an inorganic culture medium to obtain the second generation domesticated seed solution after domestication; Step 13': taking part of the second generation domesticated seed solution and inoculating it into an inorganic culture medium, and obtaining the third generation domesticated seed solution after domestication; Step 14': Take part of the third generation domesticated seed solution and inoculate it into an inorganic culture medium, and store it in a refrigerator after domestication to serve as the domesticated seed solution.

9. The method for treating coking wastewater by using micro-nano bubbles to enhance aerobic microorganisms according to claim 8, characterized in that: The phenol concentration in the inorganic culture medium in step 11' is less than the phenol concentration in the inorganic culture medium in step 12' and less than the phenol concentration in the inorganic culture medium in step 13' and less than the phenol concentration in the inorganic culture medium in step 14'.

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