Cultivation method of activated sludge for treating coking wastewater

Abstract

The present invention discloses a method for cultivating activated sludge for efficiently treating coking wastewater. The present invention adopts bio-fortified strains and rice husk biochar to prepare a microbial immobilization carrier, and the carrier is added to a simulated coking wastewater activated sludge treatment system to form bio-fortified activated sludge, which is successively added to simulated coking wastewater with gradually increasing phenol concentration, simulated coking wastewater with gradually increasing nitrogen-containing heterocyclic compound concentration, and simulated coking wastewater with gradually increasing polycyclic aromatic hydrocarbon concentration for three times of acclimation to obtain activated sludge after the third acclimation, and the activated sludge is applied to treat simulated coking wastewater. The activated sludge after the third acclimation of the present invention can simultaneously and efficiently degrade multiple target pollutants in the simulated coking wastewater.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater biological treatment, and in particular to a method for cultivating activated sludge for treating coking wastewater. Background Art

[0002] The large discharge volume of industrial wastewater, wide pollution range, and various types of pollutants have become the key difficulties in water treatment. Among them, coking wastewater has become the key and difficulty in industrial wastewater treatment due to its high COD, high ammonia nitrogen, strong toxicity, drastic water quality fluctuations, and difficulty in treatment. There are more than 300 types of compounds in coking wastewater, mainly including phenols, nitrogen-containing heterocyclic compounds, polycyclic aromatic hydrocarbons, etc. These substances are highly toxic and will not only cause serious harm to the environment, but also directly threaten human health.

[0003] At present, the main treatment methods for coking wastewater are physical, chemical and biological methods. At present, the use of bioaugmentation technology to treat coking wastewater is one of the research hotspots. For example, the literature: Study on the bioaugmentation treatment of phenol wastewater in sequencing batch reactor, Environmental Pollution and Control, Vol. 30, No. 5, records that 4 strains of highly efficient phenol metabolizing bacteria were used to Pseudomonas sp. ZW12, Acineobacters sp. UW7, Plesiomonas sp AW28 and Brevibacterium sp SW34 was added to the SBR reactor in three batches, and the activated sludge from the secondary sedimentation tank of a steel coking plant was used as inoculum sludge to carry out bioaugmentation treatment of coking wastewater. The experimental results showed that with the extension of bioaugmentation time, the settling performance of activated sludge was significantly improved, and it was helpful to improve the sludge granulation performance. After bioaugmentation with these four mixed bacteria, the bioaugmentation system significantly improved the phenol metabolism rate and phenol tolerance. Within 2 hours, the enhanced system can metabolize 730-960 mg / L phenol to 0 mg / L; within 6 hours, the enhanced system can completely metabolize 2080 mg / L phenol, and the metabolic capacity of phenol is increased by 1.36 times; within 6 hours, the enhanced system can remove 2400 mg / L phenol by 60.1%. However, the experiment was conducted with phenol as the single pollutant in the coking wastewater. There are a large number of pollutants in the actual coking wastewater, including not only phenols, but also a variety of polycyclic aromatic hydrocarbons and nitrogen-containing heterocyclic compounds. Due to the complex composition of coking wastewater, simply removing phenol cannot meet the purification needs of coking wastewater.

[0004] Phenol, nitrogen-containing heterocyclic compounds and polycyclic aromatic hydrocarbons such as pyridine and quinoline, naphthalene and phenanthrene are characteristic pollutants in coking wastewater. The first stage of biodegradation of phenol, nitrogen-containing heterocyclic compounds represented by pyridine and quinoline and phenol is an oxidation process, which requires electron donors and molecular oxygen. The coexistence of phenol and nitrogen-containing heterocyclic compounds will lead to competition between molecular oxygen and electron donors, thus reducing the removal efficiency. In addition, polycyclic aromatic hydrocarbons represented by naphthalene and phenanthrene have strong biological toxicity, and the activated sludge system is easily inhibited by their toxicity.

[0005] In summary, how to obtain an activated sludge that can simultaneously and efficiently treat phenol, nitrogen-containing heterocyclic compounds and polycyclic aromatic hydrocarbons in coking wastewater has become a problem that needs to be solved urgently. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for cultivating activated sludge for treating coking wastewater. The activated sludge cultivated by the present invention can efficiently degrade multiple target pollutants such as phenol, nitrogen-containing heterocyclic compounds, and polycyclic aromatic hydrocarbons in the coking wastewater. After treating the coking wastewater for four hours, the removal rate of phenol, nitrogen-containing heterocyclic compounds, and polycyclic aromatic hydrocarbons reaches more than 99%.

[0007] To achieve the above purpose, the technical solution designed by the present invention is as follows:

[0008] The present invention provides a method for cultivating activated sludge for efficiently treating coking wastewater, comprising the following steps:

[0009] (1) Preparation of microbial immobilization carrier agent:

[0010] Rhodococcus biphenylophilus Rhodococcus biphenylivorans Mixing with adsorbed biochar to prepare a microbial solid carrier agent;

[0011] (2) Bioaugmentation of activated sludge:

[0012] The activated sludge was inoculated into the SBR reactor and the first simulated coking wastewater containing 50 mg / L phenol as a single pollutant was injected to form an activated sludge coking wastewater treatment system, and the microbial immobilization carrier agent was directly added into the activated sludge coking wastewater treatment system to form a bio-enhanced activated sludge coking wastewater treatment system;

[0013] (3) The first domestication of activated sludge:

[0014] After the bio-augmented activated sludge coking wastewater treatment system runs stably, the concentration of phenol in the first simulated coking wastewater is gradually increased until it reaches 2000 mg / L of phenol, and the activated sludge is collected to obtain the activated sludge after the first acclimation;

[0015] (4) Second domestication of activated sludge:

[0016] The activated sludge after the first acclimation is inoculated into the SBR reactor and the second simulated coking wastewater containing mixed pollutants of 1000 mg / L phenol and 10 mg / L nitrogen-containing heterocyclic compounds is injected, and the concentration of the nitrogen-containing heterocyclic compounds in the second simulated coking wastewater is gradually increased until the concentration of the nitrogen-containing heterocyclic compounds reaches 300 mg / L, and the activated sludge is collected to obtain the activated sludge after the second acclimation;

[0017] (5) The third domestication of activated sludge:

[0018] The activated sludge after the second acclimation was inoculated into the SBR reactor and the third simulated coking wastewater containing various mixed pollutants such as 1000 mg / L phenol, 300 mg / L nitrogen-containing heterocyclic compounds and 2 mg / L polycyclic aromatic hydrocarbons was injected. The concentration of polycyclic aromatic hydrocarbons in the third simulated coking wastewater was gradually increased until it reached 40 mg / L of polycyclic aromatic hydrocarbons. The activated sludge was collected to obtain activated sludge for efficient treatment of coking wastewater.

[0019] Furthermore, in the step 1), the deposit number of the biphenylophilic Rhodococcus is CCTCC NO: M2019087, and the strain is named as biphenylophilic Rhodococcus B403 ( Rhodococcus biphenylivorans B403).

[0020] Furthermore, in the step (1), the specific preparation process of the microbial immobilized carrier bacterial agent is to first activate the biphenyl-loving Rhodococcus to the logarithmic phase, and then transfer the logarithmic phase Rhodococcus to the LB culture medium mixed with 1-2% biochar particles according to an inoculation amount of 1-2% by volume, and continue to culture for 10-24 hours to obtain the microbial immobilized carrier bacterial agent.

[0021] Furthermore, in the step (2), the volume of the inoculated microbial immobilization carrier agent accounts for 10% to 20% of the volume of the activated sludge; the components and contents of the first simulated coking wastewater include 50 to 2000 mg / L phenol, 40 to 80 mg / L NH4Cl, 40 mg / L KH2PO4, 20 mg / L MgSO4·7H2O, 10 mg / L CaCl2·2H2O, 480 mg / L NaHCO3 and 0.5 mL / L trace elements.

[0022] Furthermore, in the step (3), the first acclimation of the activated sludge includes six gradients, and the phenol and NH4Cl concentrations of the first simulated coking wastewater in the six gradients are: 50 mg / L, 40 mg / L; 100 mg / L, 40 mg / L; 200 mg / L, 80 mg / L; 500 mg / L, 80 mg / L; 1000 mg / L, 40 mg / L; 2000 mg / L, 40 mg / L.

[0023] Furthermore, in step (4), the nitrogen-containing heterocyclic compound is at least one of pyridine and quinoline, and the components and contents of the second simulated coking wastewater include 1000 mg / L of phenol, 10-300 mg / L of nitrogen-containing heterocyclic compounds, 40 mg / L of NH4Cl, 40 mg / L of KH2PO4, 20 mg / L of MgSO4·7H2O, 10 mg / L of CaCl2·2H2O, 480 mg / L of NaHCO3, and 0.5 mL / L of trace elements;

[0024] The second acclimation stage includes three processes, and the parameters in the three processes are as follows: in the first process, the concentration of the nitrogen-containing heterocyclic compound is gradually increased from 10 mg / L to 300 mg / L, and the full aeration mode is adopted to control the dissolved oxygen DO to 2-6 mg / L; in the second process, the concentration of the nitrogen-containing heterocyclic compound is 300 mg / L, and the full aeration mode is adopted to control the dissolved oxygen DO to 2-6 mg / L, and 80 mg / L of anhydrous sodium acetate is added to the second simulated coking wastewater; in the third process, the concentration of the nitrogen-containing heterocyclic compound is 300 mg / L, and the intermittent aeration mode is adopted, according to the alternation of aeration for 6 hours and aeration for 6 hours per day, the dissolved oxygen DO during the aeration period is 2-6 mg / L, and the dissolved oxygen DO during the aeration period is 0.1-0.2 mg / L, and 80 mg / L of anhydrous sodium acetate is added to the second simulated coking wastewater.

[0025] Further, in the step 5), the polycyclic aromatic hydrocarbons are at least one of naphthalene and phenanthrene, and the components of the third simulated coking wastewater include 1000 mg / L phenol, 150 mg / L pyridine, 150 mg / L quinoline, 2-40 mg / L polycyclic aromatic hydrocarbons, 40 mg / L NH4Cl, 40 mg / L KH2PO4, 20 mg / LMgSO4·7H2O, 10 mg / LCaCl2·2H2O, 480 mg / LNaHCO3 and 0.5 mL / L trace elements;

[0026] The third acclimation of the activated sludge includes six steps of acclimation, and the concentrations of polycyclic aromatic hydrocarbons in the six gradients of simulated coking wastewater are: 2 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 30 mg / L, and 40 mg / L, respectively.

[0027] Furthermore, the volume ratio of the activated sludge to the first simulated coking wastewater, the volume ratio of the activated sludge after the first acclimation to the second simulated wastewater, and the volume ratio of the activated sludge after the second acclimation to the third simulated wastewater are all 1:4.5-5.5.

[0028] The present invention also provides an application of activated sludge cultured by the method to treat coking wastewater containing multiple pollutants such as phenol, nitrogen-containing heterocyclic compounds, and polycyclic aromatic hydrocarbons, wherein the concentration of phenol in the coking wastewater reaches up to 1000 mg / L, the concentration of nitrogen-containing heterocyclic compounds reaches up to 300 mg / L, and the concentration of polycyclic aromatic hydrocarbons reaches up to 40 mg / L.

[0029] Furthermore, the nitrogen-containing heterocyclic compound is at least one of pyridine and quinoline, the polycyclic aromatic hydrocarbon compound is at least one of naphthalene and phenanthrene, the dissolved oxygen of the activated sludge treatment system is controlled to be 2-6 mg / L, and the temperature is 16-25°C. After the cultured activated sludge treats the coking wastewater for four hours, the removal rate of phenol, nitrogen-containing heterocyclic compounds and polycyclic aromatic hydrocarbon compounds reaches more than 99%.

[0030] The beneficial effects of the present invention are:

[0031] (1) The large specific surface area, surface charge, and porosity of biochar make it a potential target for pollutants (such as NH4 + -N) is a potential adsorbent of biochar. On the other hand, biochar has rich surface functional groups, which play a role in surface adsorption. The main adsorption process of biochar on aromatic pollutants is n-π / π-π interaction. When the pyrolysis temperature is 500°C, the number of π-π bonds is the largest. In the present invention, the preparation temperature of rice husk biochar is 500°C, which increases the number of π-π bonds and improves the adsorption of phenol and NH4 + Adsorption of -N. Phenol and NH4 + -N is rapidly absorbed by biochar and dispersed into its internal porous structure, and then decomposed by microorganisms in biochar. Adsorption of biochar-B403 carrier promotes the binding of microorganisms in activated sludge with target pollutants in simulated coking wastewater, and the binding of microorganisms in activated sludge with target pollutants in simulated coking wastewater (phenol and NH4 + -N) distance was significantly shortened; the adsorbed biochar-B403 carrier greatly enhanced the electron transfer by promoting the movement of electrons from the inside of the cell to the extracellular receptors.

[0032] (2) Bio-enhanced strain Rhodococcus biphenylophilus Rhodococcus biphenylivorans B403 has the ability to degrade phenol, but not pyridine, quinoline, naphthalene and phenanthrene. The acclimatization of activated sludge is divided into three stages, which slowly adapt the activated sludge to the coking wastewater environment with multiple high-concentration pollutants, and gradually adjust the microbial community structure, functional gene expression and metabolic pathways of the activated sludge to achieve efficient degradation of multiple pollutants.

[0033] (3) Phenol, pyridine and quinoline are characteristic pollutants in coking wastewater, and the first stage of their biodegradation is an oxidation process, which requires electron donors and molecular oxygen. The coexistence of phenol, pyridine and quinoline may lead to competition between molecular oxygen and electron donors, resulting in reduced removal efficiency. In the present invention, the second acclimation stage is divided into three processes. The first process is mainly to acclimate the removal capacity of the target pollutants of the activated sludge, and the second and third processes are mainly to acclimate the NH4 + -N, NO3 - -N removal capacity. In the first process, the concentration of nitrogen-containing heterocyclic compounds increases from 10 mg / L to 300 mg / L. The first process adopts a full aeration mode to control the dissolved oxygen DO to 2~6 mg / L. Maintaining a full aeration high dissolved oxygen mode of 2~6 mg / L is beneficial to the degradation of phenol, pyridine and quinoline under the coexistence conditions. In the final third process, an intermittent aeration mode is adopted. When there is no aeration, the dissolved oxygen DO decreases to form an anoxic / anaerobic state, which is beneficial to improving the denitrification performance of the activated sludge treatment system. In addition, in the second and third processes, the present invention also adds anhydrous sodium acetate. After a long period of acclimation, the activated sludge will cause NH4 + -N accumulation is too high, so anhydrous sodium acetate is added in the second and third processes. Anhydrous sodium acetate provides a large amount of carbon source, which helps to reduce NH4 + The accumulation of -N is beneficial to improving the ammonia nitrogen degradation capacity of activated sludge.

[0034] (4) In the presence of phenol, pyridine and quinoline, the two reactors still achieved efficient degradation of naphthalene and phenanthrene. First, the phenol concentration was high (2000 mg / L) during the first acclimatization. Second, pyridine, quinoline, naphthalene, phenanthrene and phenol have structural similarities to a certain extent, and high-concentration phenol acclimatization is conducive to the degradation of pyridine, quinoline, naphthalene and phenanthrene. During the second (pyridine and quinoline) and third acclimatizations (naphthalene and phenanthrene), the concentrations of the target pollutants, nitrogen-containing heterocyclic compounds and polycyclic aromatic hydrocarbons, increased slowly and the acclimatization time was longer, which was conducive to the gradual adaptation of the reactor to the degradation of nitrogen-containing heterocyclic compounds and polycyclic aromatic hydrocarbons. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the device for simulating the activated sludge treatment system of coking wastewater;

[0036] Figure 2 This is a graph showing the change in the removal performance of phenol, pyridine and quinoline in the reactor of Example 4;

[0037] Figure 3 This is the MLSS and MLVSS variation diagram of the reactor in Example 4;

[0038] Figure 4 This is the SVI variation diagram of the reactor in Example 4;

[0039] Figure 5 This is a graph showing the change in removal performance of phenol, pyridine, quinoline, naphthalene and phenanthrene in the reactor of Example 5;

[0040] Figure 6 This is a graph showing the phenol degradation results of adding untamed activated sludge into simulated coking wastewater in Example 6;

[0041] Figure 7 This is a graph showing the change in removal performance of phenol, pyridine, quinoline, naphthalene and phenanthrene in the reactor of Example 6;

[0042] Figure 8 This is a graph showing the change in the removal performance of ammonia nitrogen, nitrate nitrogen and nitrite nitrogen in the reactor of Example 6;

[0043] Fig. 9 The reactor of Example 4 is NH4 + -N、NO3 - -N and NO2 - -N removal. DETAILED DESCRIPTION

[0044] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand.

[0045] Example 1 Preparation of a microbial solid carrier agent by using biochar to fix biphenylophilic Rhodococcus

[0046] 1. Preparation of microbial immobilization carrier:

[0047] (1) Use LB medium to culture Rhodococcus biphenyl Rhodococcus biphenylivorans B403 (Deposit Number CCTCC NO: M2019087) was cultured in a shaker at 28°C and 200 rpm for 24 h to prepare the bioaugmentation agent.

[0048] (2) The rice husk biochar was sterilized by high-pressure steam sterilization at 121°C for 30 min. The rice husk biochar was directly purchased from a commercial source.

[0049] (3) Add 1 mL of bio-enhanced bacterial agent to 100 mL of LB liquid culture medium, then add 1 g of sterilized rice husk biochar and mix well. Incubate in a shaker at 28 °C and 200 rpm for 24 h for immobilization to obtain a microbial solid carrier bacterial agent.

[0050] Example 2 Bioaugmentation of activated sludge

[0051] (1) The activated sludge used in this example was taken from the aeration tank of the sewage treatment plant in Jiangxia District, Wuhan City. The activated sludge was washed and sieved to remove large particles of impurities before use. The concentration of mixed liquor suspended solids (MLSS) and mixed liquor volatile suspended solids (MLVSS) in the inoculated sludge were 2.16 g / L and 1.73 g / L, respectively.

[0052] (2) The formula of simulated coking wastewater (mg / mL): phenol: 50, NH4Cl: 40, KH2PO4: 40, MgSO4·7H2O: 20, CaCl2·2H2O: 10, NaHCO3: 480, trace elements: 0.5 mL / L; the formula of trace elements is as follows (mg / L): FeCl3·6H2O: 1500, KI: 150, MnCl2·4H2O: 110, ZnSO4·7H2O: 120, CuSO4·5H2O: 50, CoCl2·6H2O: 150, Na2MoO4·2H2O: 60, H3BO3: 150.

[0053] (3) The simulated coking wastewater activated sludge treatment system adopts a sequencing batch activated sludge reactor (SBR reactor). The schematic diagram of the device is shown in Figure 1 The effective volume of the reactor is 6 L, of which 1 L is activated sludge and 5 L is simulated coking wastewater.

[0054] (4) The microbial solidified carrier agent prepared in Example 1 was directly added into a simulated coking wastewater activated sludge treatment system to obtain bio-augmented activated sludge through the microbial solidified carrier agent.

[0055] Example 3 First acclimatization of activated sludge

[0056] Gradually increase the phenol concentration in the simulated wastewater and set the system parameters: set the SBR operation cycle to 24 h, including 2 h of water inlet, 18 h of reaction, 2 h of sedimentation, and 2 h of effluent. In the initial stage, the phenol concentration of the simulated coking wastewater was 50 mg / L, and the NH4Cl concentration was 40 mg / L. The initial MLSS and MLVSS concentrations of the inoculated sludge were 2.16 g / L and 1.74 g / L, respectively. The room temperature of the reactor was maintained at 25 degrees Celsius, and the DO in the reactor was 2-6 mg / L. The reactor inlet settings are shown in Table 1. The results show that the activated sludge after the first acclimation had a phenol removal rate of more than 99% for 2000 mg / L, a COD removal rate of more than 98%, and NH4 + The -N removal rate reached more than 95%, and the MLSS and MLVSS of the activated sludge were 5.42 g / L and 5.22 g / L, respectively, indicating that the biomass of the activated sludge still showed an increasing trend in the presence of high concentration of phenol. The SVI of the activated sludge was 53 mL / g, indicating that the sedimentation quality of the activated sludge was good.

[0057] Table 1 Example 3 Reactor water inlet settings

[0058]

[0059] Example 4 Second acclimatization of activated sludge

[0060] (1) The activated sludge after the first acclimation was divided into two equal parts as the inoculum sludge for acclimation in this example. The reactors were set up as follows: the SBR1 reactor (referred to as the R1 reactor) was a pyridine degradation reactor, and the SBR2 reactor (referred to as the R2 reactor) was a quinoline degradation reactor. Each reactor contained 300 mL of activated sludge and 1.5 L of simulated coking wastewater.

[0061] (2) The reactor inlet settings are shown in Table 2. The simulated coking wastewater was configured as follows (mg / L): phenol: 1000, pyridine (concentration range 10-300 mg / L), quinoline (concentration range 10-300 mg / L), NH4Cl: 40, KH2PO4: 40, MgSO4·7H2O: 20, CaCl2·2H2O: 10, NaHCO3: 480, trace elements: 0.5 mL / L, and the trace element formula was the same as in Example 1. In the initial stage, the concentrations of pyridine and quinoline in the simulated coking wastewater were 10 mg / mL, the reactor room temperature was maintained at 25°C, the DO in the reactor was 2-6 mg / L, the first and second processes adopted the full aeration mode, and the third process adopted the intermittent aeration mode to restore the denitrification performance in the reactor. The purpose of adding anhydrous sodium acetate in the second and third processes is to provide a carbon source, because the ammonia nitrogen effluent concentration is very high, and the carbon source can affect the degradation of ammonia nitrogen.

[0062] Table 2 Example 4 Reactor water inlet settings

[0063]

[0064] (3) The simulated coking wastewater of different processes was prepared according to the pyridine / quinoline concentration from low to high. In the first process, the pyridine / quinoline concentration of the simulated coking wastewater was gradually increased until it reached the highest concentration of pyridine / quinoline 300 mg / L. After the three processes, the activated sludge in the SBR1 reactor was collected as the pyridine-acclimated activated sludge, and the activated sludge in the SBR2 reactor was collected as the quinoline-acclimated activated sludge.

[0065] Combination Figure 2 As shown, Figure 2 The degradation of phenol, pyridine and quinoline in two reactors during the entire operation period (a total of 133 days) is shown, with a phenol influent concentration of 1000 mg / L and initial pyridine and quinoline influent concentrations of 10 mg / L. Figure 2 As shown, during the entire operation, the average phenol, pyridine and quinoline removal rates of the two reactors were all above 99%. Phenol, pyridine and quinoline are characteristic pollutants in coking wastewater, and the first stage of their biodegradation is an oxidation process, which requires electron donors and molecular oxygen. Previous research reports have shown that the coexistence of phenol, pyridine and quinoline will lead to competition between molecular oxygen and electron donors, resulting in reduced removal efficiency. In this embodiment, the biodegradation of phenol, pyridine and quinoline is not affected by their coexistence. This phenomenon is attributed to the fact that the first process of this embodiment adopts a high dissolved oxygen DO strategy, adopts a full aeration mode, and controls the dissolved oxygen DO to 2~6 mg / L.

[0066] Combination Fig. 9 As shown, at the end of the first process, at 73-75 days, the effluent NH4 + -N concentration is higher than influent NH4 + -N concentration, so in the second process, anhydrous sodium acetate was added in this embodiment, and NH4 + The removal rate of -N was restored to 100%, indicating that the addition of anhydrous sodium acetate in the second process was beneficial to the removal of NH4 + -N degradation.

[0067] Combination Fig. 9 As shown, at the end of the second process, the reactor effluent NO3 - -N concentration gradually increased to 110-140 mg / L, indicating that DNB in ​​the reactor was severely inhibited. In the third process of this embodiment, the denitrification performance of the activated sludge was improved by continuously adding anhydrous sodium acetate to provide a carbon source and using intermittent aeration to provide anaerobic conditions. Fig. 9As shown in the figure, after intermittent aeration and the addition of anhydrous sodium acetate, the reactor effluent NO3 - The average concentration of -N was lower than 0.03 mg / L, which significantly improved the denitrification performance of activated sludge and increased NO3 - -N removal rate.

[0068] Through three-step acclimation, the two reactors reacted with NH4 + The average removal rates of -N were 99.16%, 97.32% and 97.89% respectively. Figure 3 As shown in the figure, the MLSS and MLVSS of the activated sludge in the SBR1 reactor gradually increased from 1.39g / L and 1.60g / L to 6.62g / L and 5.91g / L, and the MLSS of the activated sludge in the SBR2 reactor gradually increased from 1.62g / L and 1.29g / L to 7.68g / L and 7.19g / L. Figure 4 As shown, the SVI showed a general downward trend with the operation of the reactor. The SVI of the activated sludge in the SBR1 reactor decreased from 100.42 mL / g to 33.20 mL / g, and the SVI of the activated sludge in the SBR2 reactor decreased from 148.53 mL / g to 46.22 mL / g.

[0069] Example 5 The third acclimatization of activated sludge

[0070] (1) The inoculated sludge used in this embodiment is the activated sludge in the SBR1 reactor or the activated sludge in the SBR2 reactor collected after the end of Example 4. The properties of the two activated sludges are basically the same. Either one can be selected for the third acclimation. The activated sludge in the SBR1 reactor is selected in this embodiment. The reactors are set as follows: the R1 reactor is a naphthalene degradation reactor, and the R2 reactor is a phenanthrene degradation reactor. Each reactor contains 300 mL of activated sludge and 1.5 L of simulated coking wastewater.

[0071] (2) The inlet settings of each reactor are shown in Table 3. The simulated coking wastewater is configured as follows (mg / L): phenol: 1000, pyridine 150, quinoline: 150, naphthalene (concentration range is 2-40 mg / L), phenanthrene (concentration range is 2-40 mg / L), NH4Cl: 40, KH2PO4: 40, MgSO4·7H2O: 20, CaCl2·2H2O: 10, NaHCO3: 480, trace elements: 0.5 mL / L, and the trace element formula is the same as in Example 2. In the initial stage, the concentrations of naphthalene and phenanthrene in the simulated coking wastewater are 10 mg / mL, the reactor room temperature is maintained at 25 degrees Celsius, and the DO in the reactor is 2-6 mg / L.

[0072] Table 3 Example 5 Reactor water inlet settings

[0073]

[0074] (3) Prepare simulated coking wastewater at different stages according to the naphthalene / phenanthrene concentration from low to high. After the initial activated sludge coking wastewater treatment system runs stably, gradually increase the naphthalene / phenanthrene concentration of the simulated coking wastewater until the highest concentration of naphthalene / phenanthrene is reached. After the cycle is over, collect the activated sludge in the reactor to obtain activated sludge that has been acclimated three times.

[0075] Figure 5 The changes in the removal performance of phenol, pyridine, quinoline, naphthalene and phenanthrene in the two reactors during the entire operation cycle (74 days in total) are shown. During the entire operation process, the average phenol removal rate of each reactor is above 99%, the average pyridine removal rate and the average quinoline removal rate in the two reactors R1 and R2 are also over 99%, and the removal rates of naphthalene and phenanthrene are also higher than 99%, indicating that the two reactors still achieve efficient degradation of naphthalene and phenanthrene under the simultaneous presence of phenol, pyridine and quinoline.

[0076] Example 6 Simultaneous degradation of phenol, nitrogen-containing heterocyclic compounds and polycyclic aromatic hydrocarbons by activated sludge after three acclimation

[0077] (1) The inoculated sludge used in this example is the activated sludge collected after the end of the cycle in Example 4. The properties of the activated sludge in the two reactors R1 and R2 are basically the same, and either one can be selected. In this example, the activated sludge in the R1 reactor is selected. The reactor contains 300 mL of activated sludge and 1.5 L of simulated coking wastewater.

[0078] (2) The simulated coking wastewater was configured as follows (mg / L): phenol: 1000, pyridine: 150, quinoline: 150, naphthalene: 40, phenanthrene: 40, NH4Cl: 40, KH2PO4: 40, MgSO4·7H2O: 20, CaCl2·2H2O: 10, NaHCO3: 480, trace elements 0.5 mL / L, the trace element formula was the same as in Example 1. The reactor room temperature was maintained at 25°C, and the DO in the reactor was 2-6 mg / L.

[0079] (3) The total operation time of the SBR reactor is 24 h. Samples are taken at 0, 2, 4, 6, 8, 10, 12, and 24 h. The effluent from the activated sludge treatment system is filtered through a 0.22 μm filter membrane and then tested for phenol, nitrogen-containing heterocyclic compounds, and polycyclic aromatic hydrocarbons. The test methods are as follows: phenol is tested by 4-aminoantipyrine spectrophotometry; ammonia nitrogen is tested by Nessler's reagent spectrophotometry; nitrate nitrogen is tested by ultraviolet spectrophotometry; nitrite nitrogen is tested by spectrophotometry; MLSS and MLVSS are tested by weight method;

[0080] Nitrogen-containing heterocyclic compounds were determined by high performance liquid chromatography, and the specific detection conditions were as follows:

[0081] 1) Pyridine detection conditions: methanol: deionized water = 60:40, flow rate 1 mL·min -1 , detection wavelength 254 nm, column temperature 25°C, injection volume 10 μL. The elution times of pyridine and 2-hydroxypyridine were approximately 2.2 min and 1.8 min;

[0082] 2) The mobile phase volume ratio of quinoline is methanol (A): deionized water (B) = 60:40, and the flow rate is 1 mL min -1 , detection wavelength 271 nm, column temperature 25°C, injection volume 10 μL. The elution times of quinoline and 2-hydroxyquinoline were approximately 2.7 min and 5.2 min.

[0083] The determination of naphthalene and phenanthrene was carried out by high performance liquid chromatography. The specific detection conditions were as follows: 80% methanol (A) + 20% deionized water (B), maintained for 20 min; the flow rate was increased by 1.2% methanol / min to 95% methanol + 5% water, maintained for 45 min. Flow rate 1 mL·min -1 , detection wavelength 254 nm, column temperature 25°C, injection volume 10 μL. The elution times of naphthalene and phenanthrene are approximately 2 min and 11 min.

[0084] (4) Changes in removal performance of phenol, pyridine, quinoline, naphthalene and phenanthrene

[0085] The results are as follows Figure 7 As shown. Figure 7 It can be seen that in the composite system of the four pollutants in the reactor, the removal rates of phenol, pyridine, quinoline, naphthalene and phenanthrene in the reactor all reached more than 99% at 4 hours, indicating that the activated sludge after three acclimation in the present invention can simultaneously degrade phenol, pyridine, quinoline, naphthalene and phenanthrene, and can simultaneously obtain a higher removal rate of the above target pollutants.

[0086] The comparative example is the activated sludge directly taken from the aeration tank of the municipal treatment plant in Example 2. Figure 6 As shown in the figure, the degradation of phenol added to the simulated coking wastewater. After 24 hours of reaction, the concentrations of phenol and ammonia nitrogen still reached more than 800 mg / L, indicating that when untamed activated sludge is added to the simulated coking wastewater containing high concentration of phenol, activated sludge collapse will occur.

[0087] (5) Changes in removal performance of ammonia nitrogen, nitrate nitrogen and nitrite nitrogen

[0088] The results are as follows Figure 8 As shown. Figure 8It can be seen that the activated sludge obtained by three acclimation cultures in this embodiment is applied to coking wastewater, and the effluent ammonia nitrogen and nitrite nitrogen are both 0, and the effluent nitrate nitrogen R1 and R2 are about 6.38 mg / L and 2.11 mg / L. This shows that the activated sludge after three acclimation cultures in the present invention also has good removal performance of ammonia nitrogen, nitrate nitrogen and nitrite nitrogen.

[0089] Although the above embodiments have been described in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all belong to the protection scope of the present invention.

Claims

1. A method for cultivating activated sludge for treating coking wastewater, characterized in that: The following steps are involved: (1) Preparation of microbial immobilization carrier agent: Rhodococcus biphenylophilus Rhodococcus biphenylivorans Mixing with adsorbed biochar to prepare a microbial solid carrier agent; (2) Bioaugmentation of activated sludge: The activated sludge was inoculated into the SBR reactor and the first simulated coking wastewater containing 50 mg / L phenol as a single pollutant was injected to form an activated sludge coking wastewater treatment system, and the microbial immobilization carrier agent was directly added into the activated sludge coking wastewater treatment system to form a bio-enhanced activated sludge coking wastewater treatment system; (3) The first domestication of activated sludge: After the bio-augmented activated sludge coking wastewater treatment system runs stably, the concentration of phenol in the first simulated coking wastewater is gradually increased until it reaches 2000 mg / L of phenol, and the activated sludge is collected to obtain the activated sludge after the first acclimation; (4) Second domestication of activated sludge: The activated sludge after the first acclimation was inoculated into the SBR reactor and the second simulated coking wastewater containing mixed pollutants of 1000 mg / L phenol and 10 mg / L nitrogen-containing heterocyclic compounds was injected, and the concentration of the nitrogen-containing heterocyclic compounds in the second simulated coking wastewater was gradually increased until the concentration of the nitrogen-containing heterocyclic compounds reached 300 mg / L, and the activated sludge was collected to obtain the activated sludge after the second acclimation; (5) The third domestication of activated sludge: The activated sludge after the second acclimation is inoculated into the SBR reactor and the third simulated coking wastewater containing a variety of mixed pollutants such as 1000 mg / L phenol, 300 mg / L nitrogen-containing heterocyclic compounds and 2 mg / L polycyclic aromatic hydrocarbons is injected, the concentration of polycyclic aromatic hydrocarbons in the third simulated coking wastewater is gradually increased until the concentration of polycyclic aromatic hydrocarbons reaches 40 mg / L, and the activated sludge is collected to obtain the activated sludge for treating coking wastewater; In the step (4), the nitrogen-containing heterocyclic compound is at least one of pyridine and quinoline, and the components and contents of the second simulated coking wastewater include 1000 mg / L of phenol, 10-300 mg / L of nitrogen-containing heterocyclic compounds, 40 mg / L of NH4Cl, 40 mg / L of KH2PO4, 20 mg / L of MgSO4·7H2O, 10 mg / L of CaCl2·2H2O, 480 mg / L of NaHCO3, and 0.5 mL / L of trace elements; The second acclimation stage includes three processes, and the parameters in the three processes are as follows: in the first process, the concentration of the nitrogen-containing heterocyclic compound is gradually increased from 10 mg / L to 300 mg / L, and the full aeration mode is adopted to control the dissolved oxygen DO to 2-6 mg / L; in the second process, the concentration of the nitrogen-containing heterocyclic compound is 300 mg / L, and the full aeration mode is adopted to control the dissolved oxygen DO to 2-6 mg / L, and 80 mg / L of anhydrous sodium acetate is added to the second simulated coking wastewater; The concentration of nitrogen-containing heterocyclic compounds in the third process was 300 mg / L. An intermittent aeration mode was adopted, with 6 hours of aeration and 6 hours of aeration alternating every day. The dissolved oxygen DO during the aeration period was 2~6 mg / L, and the dissolved oxygen DO during the aeration period was 0.1~0.2 mg / L. 80 mg / L of anhydrous sodium acetate was added to the second simulated coking wastewater.

2. The method for cultivating activated sludge for treating coking wastewater according to claim 1, characterized in that: In the step (1), the deposit number of the biphenylophilic Rhodococcus is CCTCC NO: M2019087, and the strain is named as biphenylophilic Rhodococcus B403.

3. The method for cultivating activated sludge for treating coking wastewater according to claim 1, characterized in that: In the step (1), the specific preparation process of the microbial immobilized carrier bacterial agent is to first activate the biphenylophilic Rhodococcus to the logarithmic phase, then transfer the biphenylophilic Rhodococcus bacterial liquid in the logarithmic phase to an LB culture medium mixed with 1-2% by mass of biochar particles according to an inoculation amount of 1-2% by volume, and continue to culture for 10-24 hours to obtain the microbial immobilized carrier bacterial agent.

4. The method for cultivating activated sludge for treating coking wastewater according to claim 1, characterized in that: In the step (2), the volume of the inoculated microbial immobilization carrier inoculum accounts for 10% to 20% of the volume of the activated sludge; the components and contents of the first simulated coking wastewater include 50 to 2000 mg / L phenol, 40 to 80 mg / L NH4Cl, 40 mg / L KH2PO4, 20 mg / L MgSO4·7H2O, 10 mg / L CaCl2·2H2O, 480 mg / L NaHCO3 and 0.5 mL / L trace elements.

5. The method for cultivating activated sludge for treating coking wastewater according to claim 1, characterized in that: In the step (3), the first acclimation of the activated sludge includes six gradients, and the phenol and NH4Cl concentrations of the first simulated coking wastewater in the six gradients are: 50 mg / L, 40 mg / L; 100 mg / L, 40 mg / L; 200 mg / L, 80 mg / L; 500 mg / L, 80 mg / L; 1000 mg / L, 40 mg / L; 2000 mg / L, 40 mg / L.

6. The method for cultivating activated sludge for treating coking wastewater according to claim 1, characterized in that: In the step (5), the polycyclic aromatic hydrocarbons are at least one of naphthalene and phenanthrene, and the components of the third simulated coking wastewater include 1000 mg / L phenol, 150 mg / L pyridine, 150 mg / L quinoline, 2-40 mg / L polycyclic aromatic hydrocarbons, 40 mg / L NH4Cl, 40 mg / L KH2PO4, 20 mg / LMgSO4·7H2O, 10 mg / LCaCl2·2H2O, 480 mg / L NaHCO3 and 0.5 mL / L trace elements; The third acclimation of the activated sludge includes six steps of acclimation, and the concentrations of polycyclic aromatic hydrocarbons in the six gradients of simulated coking wastewater are: 2 mg / L, 5 mg / L, 10 mg / L, 20 mg / L, 30 mg / L, and 40 mg / L, respectively.

7. The method for cultivating activated sludge for treating coking wastewater according to claim 1, characterized in that: The volume ratio of the activated sludge to the first simulated coking wastewater, the volume ratio of the activated sludge after the first acclimation to the second simulated wastewater, and the volume ratio of the activated sludge after the second acclimation to the third simulated wastewater are all 1:4.5-5.

5.

8. An application of the activated sludge obtained by the culturing method according to any one of claims 1 to 7 in treating coking wastewater containing multiple pollutants such as phenol, nitrogen-containing heterocyclic compounds and polycyclic aromatic hydrocarbons, characterized in that: Among them, the concentration of phenol in coking wastewater reached as high as 1000 mg / L, the concentration of nitrogen heterocyclic compounds reached as high as 300 mg / L, and the concentration of polycyclic aromatic hydrocarbons reached as high as 40 mg / L.

9. The use according to claim 8, characterized in that: The nitrogen-containing heterocyclic compound is at least one of pyridine and quinoline, the polycyclic aromatic hydrocarbon compound is at least one of naphthalene and phenanthrene, the dissolved oxygen of the activated sludge treatment system is controlled to be 2-6 mg / L, and the temperature is 16-25°C. After the cultured activated sludge treats the coking wastewater for four hours, the removal rate of phenol, nitrogen-containing heterocyclic compounds and polycyclic aromatic hydrocarbon compounds reaches more than 99%.

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