Biological treatment method for dye intermediate production wastewater

Abstract

The invention discloses a biological treatment method for dye intermediate production wastewater. The treatment method comprises the following steps: firstly, screening biological bacteria with high-efficiency degradation capability on specific pollutants of the dye intermediate wastewater, carrying out domestication culture on the biological bacteria, and then carrying out biological purification treatment on the dye intermediate wastewater by utilizing the biological bacteria, the method specifically comprises the following steps: 1, screening and domesticating biological bacteria; 2, biological purification treatment: feeding the wastewater into an adjusting tank to adjust the pH value of the wastewater to 6-9 and the temperature to 20-35 DEG C; feeding into a biological reaction tank inoculated with microbial flora capable of efficiently degrading dye intermediate wastewater for biological treatment; and finally feeding into a membrane bioreactor for deep treatment. According to the biological treatment method for the dye intermediate production wastewater, refractory organic matters in the dye intermediate wastewater can be efficiently removed, the treatment efficiency and the treatment effect of the wastewater can be improved, meanwhile, the treatment cost of the dye intermediate wastewater can be effectively reduced, and secondary pollution generated in the wastewater treatment process can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and relates to a biological treatment method for organic wastewater, in particular to a biological treatment method for dye intermediate production wastewater. Background Art

[0002] With the rapid development of the dye industry, the production scale of dye intermediates is also expanding. However, a large amount of wastewater is generated in the production process of dye intermediates. These wastewaters have the characteristics of complex composition, high concentration, and high toxicity. They contain high-concentration difficult-to-degrade organic matter such as aniline and phenol, as well as salt and heavy metals. If they are directly discharged without effective treatment, they will cause serious pollution to the environment. At present, for dye intermediate wastewater, ordinary biological treatment or advanced oxidation combined with biological treatment is generally used. The advanced oxidation mainly includes: Fenton oxidation, ozone oxidation, iron-carbon micro-electrolysis, etc. After the advanced oxidation treatment improves the biodegradability of the wastewater, biochemical treatment is used to further reduce the COD, ammonia nitrogen, total nitrogen, etc. of the wastewater to achieve the standard discharge of wastewater. However, the above-mentioned advanced oxidation method has the problems of large construction investment, high operating cost, and possible secondary pollution. Relying entirely on traditional biological treatment has the disadvantages of long treatment cycle, large fluctuation of effluent water quality, and poor system resistance to shock load. Therefore, a more efficient, economical and environmentally friendly method for treating dye intermediate production wastewater is needed.

[0003] The existing technology for treating dye intermediate wastewater includes a treatment process combining physicochemical pretreatment + biological treatment + physicochemical deep treatment. Among them, physicochemical pretreatment mainly includes chemical oxidation (such as Fenton oxidation, ozone oxidation, wet oxidation, etc.), extraction, adsorption, precipitation, filtration, concentration-incineration and other process technologies. These methods can remove some suspended matter and organic matter in the wastewater, and at the same time improve the biodegradability of the wastewater by chemically oxidizing and decomposing the difficult-to-degrade organic matter in the wastewater; biological treatment mainly includes traditional activated sludge method, SBR, MBR, biological contact oxidation and other processes, but because the common biological flora in traditional biological treatment has poor tolerance and low degradation efficiency to characteristic pollutants such as aniline and phenol in dye intermediate wastewater, the biochemical system has problems such as low volume load and poor operation stability, which seriously affects the stable discharge of the system effluent, so further deep treatment is required; deep treatment technologies mainly include chemical oxidation, activated carbon adsorption, membrane filtration, etc. Although these methods can effectively remove organic matter in wastewater, the treatment cost is high and it is easy to cause secondary pollution. In addition, the above-mentioned treatment methods generally have disadvantages such as complex process flow, high equipment investment and operating costs, and the connection and coordinated operation between different treatment processes require careful management and control, otherwise it may affect the stability and treatment effect of the entire treatment system.

[0004] It can be seen that the biological method utilizes the metabolism of microorganisms to convert organic matter in wastewater into harmless substances. It has the advantages of low treatment cost and no secondary pollution. However, there is still room for further improvement in treatment efficiency and effect. Screening, domesticating and cultivating biological bacteria that can efficiently degrade difficult-to-degrade organic matter in dye intermediate wastewater, and developing biological treatment technology methods based on the biological bacteria that can efficiently treat dye intermediate wastewater is currently a research hotspot in dye intermediate wastewater treatment. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a biological treatment method for dye intermediate production wastewater, which can effectively remove refractory organic matter in wastewater and improve the treatment efficiency and treatment effect of wastewater, while achieving the technical effect of reducing treatment costs and reducing secondary pollution.

[0006] The technical solution of the present invention is as follows:

[0007] The present invention provides a biological treatment method for dye intermediate production wastewater as follows: firstly, biological bacteria with high efficiency in degrading characteristic pollutants (including aniline and / or phenol) of dye intermediate wastewater are screened from nature and domesticated and cultured, and then the dye intermediate wastewater is subjected to biological purification treatment using the biological bacteria; specifically, the method comprises the following steps:

[0008] Step 1: Screening and domestication of biological bacteria.

[0009] First, bacterial strains that are tolerant to dye intermediate production wastewater are screened from nature. Preferably, biological bacteria capable of degrading characteristic pollutants in dye intermediate wastewater can be screened from the soil near the dye intermediate production environment (including the soil near the dye intermediate production workshop, the soil near the dye intermediate wastewater discharge port, etc.), and the dominant microbial flora is obtained by multiple screening in an enriched culture medium containing dye intermediates.

[0010] Then, the screened dominant microbial flora is domesticated, and the domesticated microbial flora (strain) is inoculated into a culture medium with gradually increasing dye intermediate concentrations, and after multiple generations of cultivation, the microorganisms are adapted to the high-concentration dye intermediate wastewater environment; preferably, the bacterial count OD inoculated into the culture medium with gradually increasing dye intermediate concentrations is 415nm =0.2-0.4, the culture conditions are temperature 25-35°C, pH 6.5-8.5, and dissolved oxygen controlled at 2-4 mg / L.

[0011] Step 2: Biological purification treatment

[0012] First, the dye intermediate wastewater is sent to the regulating tank to adjust the pH value of the wastewater to 6-9 and the temperature to 20-35°C to meet the requirements of subsequent biological treatment.

[0013] Then, the conditioned wastewater is sent to a bioreactor for biological treatment. The bioreactor is inoculated with the microbial flora screened and domesticated in step 1 that can efficiently degrade the dye intermediate wastewater. The inoculation amount OD 415nm =0.2-0.4. The microbial flora is composed of various microorganisms such as Bacillus and Pseudomonas (the amount of Bacillus and Pseudomonas is about OD 415nm =0.2-0.4, the ratio of the two is 1:1-1:3), which can quickly and effectively degrade the organic matter in the wastewater produced by the dye intermediates; under suitable conditions, the microbial flora uses the organic matter in the wastewater as nutrients, carries out metabolic activities, and converts the organic matter into harmless substances.

[0014] The biological reaction pool can adopt various biological treatment processes such as activated sludge method, biofilm method, etc.

[0015] In the activated sludge process bioreactor, the domesticated microbial flora is put into the bioreactor, the mixed liquor suspended solids (MLSS) concentration is controlled at 3000-8000 mg / L, the hydraulic retention time (HRT) is 2-5 days, and the dissolved oxygen is controlled at 1.5-6 mg / L.

[0016] In the biofilm bioreactor, microorganisms are attached to the surface of the filler to form a biofilm. The filler can be a porous composite filler made of polyethylene, polypropylene and other materials. The specific surface area of ​​the filler is 100-240m 2 / m 3 , which can provide sufficient attachment area for microorganisms and promote their growth and reproduction. The hydraulic retention time (HRT) of wastewater in the biofilm reactor is 2-5 days, and the dissolved oxygen is controlled at 1.5-6 mg / L, which can ensure that microorganisms have enough time to carry out metabolic activities and convert organic matter into harmless substances.

[0017] The wastewater after biological treatment is further treated by membrane bioreactor (MBR). The membrane assembly of MBR is microfiltration membrane or ultrafiltration membrane with a pore size of 0.01-0.4μm. MBR further removes residual organic matter and microorganisms in the wastewater to improve the quality of the treated effluent.

[0018] A small amount of biological sludge (sludge containing microorganisms, residual sludge) will be produced during the biological treatment process, which needs to be treated. The sludge is treated by concentration, dehydration, drying and other treatment processes. After the water content of the sludge is reduced to a certain level, it is finally disposed of by incineration, landfill, etc. The sludge is concentrated by gravity concentration, and the concentration time is 10-26h, which can effectively reduce the water content of the sludge. The sludge is dehydrated by a plate and frame filter press or a belt filter press. The water content of the dehydrated sludge is 60-85%, which can meet the final disposal requirements of the sludge.

[0019] Furthermore, the step 1, screening and domestication of biological bacteria, is specifically carried out according to the following method:

[0020] Collect soil samples near the dye intermediate production workshop or the dye intermediate wastewater discharge outlet, and add them to a conical flask containing enrichment culture medium at a ratio of 0.1-0.2 g / mL; or collect soil samples near the dye intermediate production workshop and the dye intermediate wastewater discharge outlet, and add them to conical flasks containing enrichment culture medium at a ratio of 0.1-0.2 g / mL respectively;

[0021] Place the conical flask in a shaker and culture for 3-5 days at a temperature of 25-35°C and a rotation speed of 100-200 r / min; then take a portion of the culture solution (10-20 mL) and transfer it to a fresh enrichment medium, repeat the culture 3-4 times to obtain a dominant microbial flora;

[0022] After culturing two different dominant microbial communities from two different soil samples, the same bacterial count ratio (OD 415nm =0.2, the ratio of the two is 1:1) mixed, and then co-acclimated and cultured;

[0023] The screened microbial strains were expressed in terms of bacterial count OD 415nm =0.2-0.4 is inoculated into a culture medium containing different concentrations of dye intermediates; the initial dye intermediate concentration is 0.1 g / L, which is gradually increased to 1 g / L; the other components of the culture medium are the same as those of the enrichment medium, the culture conditions are a temperature of 25-35°C, a pH value of 6.5-8.5, and dissolved oxygen is controlled at 2-4 mg / L; each time the dye intermediate concentration is increased, 2-3 generations of microorganisms are cultured until the microorganisms can stably grow at a dye intermediate concentration of 1 g / L.

[0024] Furthermore, the components of the enrichment medium include:

[0025] Glucose: 0.8-1.6g / L (grams / liter)

[0026] Peptone: 0.5-1.0g / L

[0027] Yeast extract: 0.3-0.5g / L

[0028] Dye intermediate: 0.1g / L

[0029] Salts: 0.3-0.8g / L

[0030] K2HPO4: 0.2-0.3g / L

[0031] MgSO4·7H2O:0.1-0.2g / L

[0032] pH value is 6.9-7.1;

[0033] The dye intermediate is a combination of one or more of p-resorcinol, m-phenylenediamine and p-nitroaniline;

[0034] The salt is a combination of one or more of KaCl, NaCl, NH4Cl, and KNO3.

[0035] The beneficial effects of the present invention are:

[0036] The biological treatment method for dye intermediate production wastewater of the present invention can effectively remove refractory organic matter in the dye intermediate wastewater, improve the treatment efficiency and treatment effect of the wastewater, and effectively ensure that the effluent of the wastewater treatment system stably meets the discharge standards. At the same time, it can effectively reduce the treatment cost of the dye intermediate wastewater and reduce the secondary pollution generated in the wastewater treatment process.

[0037] The biological treatment method for dye intermediate production wastewater provided by the present invention has the following advantages over the existing dye intermediate wastewater treatment technology:

[0038] (1) Low processing cost

[0039] Compared with chemical treatment, the present invention adopts biological treatment, and the cultivation and operation cost of microorganisms is relatively low. It does not need to use expensive chemical agents, and does not produce a large number of by-products that need subsequent treatment, such as iron mud.

[0040] (2) Good treatment effect

[0041] Through the screening and domestication of microorganisms, the microbial flora of the present invention can effectively degrade complex organic matter (such as resorcinol, m-phenylenediamine, and p-nitroaniline) in the wastewater produced by dye intermediates. After biological treatment and deep treatment, the COD removal rate of the wastewater can reach more than 90%, which can make the treated wastewater meet strict discharge standards. In addition, the biological treatment and deep treatment system of the present invention can maintain continuous and stable operation during the treatment of dye intermediate wastewater containing phenols or anilines, and has a strong impact resistance to fluctuations in the influent water quality (up to 400 mg / L), while effectively ensuring the effluent water quality requirements after the system treatment. In the existing microbial treatment technology, when the concentration of pollutants in the dye intermediate wastewater fluctuates by more than 200 mg / L, the strain will become ineffective or even die.

[0042] (3) High processing efficiency

[0043] The existing microbial treatment technology usually takes more than 5 days to treat dye intermediate wastewater with a pollutant concentration of no more than 200 mg / L, while the technology provided by the present invention only takes 4 days to treat dye intermediate wastewater with a pollutant concentration of no more than 400 mg / L. And the entire treatment process mainly relies on the biodegradation of microorganisms, and no secondary pollution will be generated. The amount of residual sludge generated in the biological treatment process is relatively small, which can be directly landfilled after exposure to sunlight and dehydration, or further subjected to anaerobic fermentation and other treatments to achieve resource recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The present invention is a process flow chart of the biological treatment method for dye intermediate production wastewater. DETAILED DESCRIPTION

[0045] Now in conjunction with the accompanying drawings and specific embodiments, the present invention will be further described in detail. These embodiments should be understood to be only used to illustrate the present invention without limiting the scope of protection of the present invention. After reading the content of the present invention, those skilled in the art can make various modifications to the present invention, and these equivalent changes and modifications also fall into the scope of protection defined by the present invention. The chemical reagents used in the following examples are all common commercial products, and the purity is chemically pure unless otherwise specified.

[0046] Example 1

[0047] The biological treatment method of dye intermediate (resorcinol) production wastewater of the present invention is as follows: firstly, biological bacteria with high efficiency in degrading characteristic pollutants (resorcinol) of dye intermediate wastewater are screened from nature and domesticated and cultured, and then the biological bacteria are used to perform biological purification treatment on the dye intermediate (resorcinol) wastewater; specifically, the following steps are included:

[0048] Step 1: Microbial screening and domestication

[0049] 10g of soil samples near the dye intermediate (resorcinol) production workshop and the dye intermediate (resorcinol) wastewater discharge port were collected and added to conical flasks containing 100mL of enrichment medium. The components of the enrichment medium include: glucose, 0.8g / L; peptone, 0.5g / L; yeast extract, 0.3g / L; resorcinol, 0.1g / L; NaCl (or KCl), 0.8g / L; K2HPO4, 0.2g / L; MgSO4·7H2O, 0.1g / L; the pH value of the enrichment medium was adjusted to 7.0 with NaOH or HCl.

[0050] The conical flask was placed in a shaker and cultured for 4 days at a temperature of 30°C and a rotation speed of 150 r / min. Then 10 mL of the culture solution was transferred to a fresh enrichment medium, and the above steps were repeated for 3-4 times to obtain a dominant microbial flora. The microbial flora was composed of a variety of microorganisms such as Bacillus and Pseudomonas (the bacterial count of Bacillus and Pseudomonas was about OD 415nm =0.2, the ratio of the two is 1:0.9-1.1). If the above steps fail, change the soil sampling location and repeat the above steps until the dominant microbial flora is successfully cultured.

[0051] The method for determining the success of the culture of the dominant microbial flora is to visually observe that the bacterial flora can survive and multiply in large quantities on the enrichment medium containing the characteristic substance (resorcinol). The method for determining the ratio of two different bacterial species (Bacillus and Pseudomonas) is to determine the ratio of the two different bacterial species by plate count method.

[0052] After culturing two different dominant microbial communities from two different soil samples, the same bacterial count ratio (OD 415nm =0.2, the ratio of the two is 1:1) and then they are co-cultured.

[0053] The dominant microbial flora obtained in the previous step was expressed as OD 415nm =0.2 was inoculated into a culture medium containing different concentrations of resorcinol (simulated dye intermediate pollutant). The initial concentration of resorcinol was 0.1 g / L, and the concentration was increased by about 10% each time, gradually increasing to 1 g / L. The other components of the culture medium were the same as those of the enrichment medium, and the culture conditions were a temperature of 28±2°C, a pH value of 7.5±0.1, and dissolved oxygen of 2.9-3.3 mg / L. Each time the dye intermediate concentration was increased, 2-3 generations of microorganisms were cultured until the microorganisms were able to grow stably at a dye intermediate (resorcinol) concentration of 1 g / L. The domesticated microbial flora was obtained.

[0054] Step (ii) Biological treatment

[0055] Biological treatment processes such as Figure 1 As shown: the dye intermediate wastewater first enters the pH adjustment device to adjust the pH value to 7.0, then enters the biological treatment system (this embodiment uses an activated sludge bioreactor) for biological treatment, and finally enters the membrane bioreactor (MBR) for deep treatment before meeting the discharge standards.

[0056] The specific operation steps of the biological treatment process are as follows:

[0057] (2.1) Take 1000L of dye intermediate wastewater, then add dilute hydrochloric acid or sodium hydroxide solution to the wastewater, adjust the pH to 6.0, inject it into the biological treatment system, and adjust the temperature to 30±2℃.

[0058] (2.2) The domesticated microbial flora obtained in step (1) was inoculated into the biological treatment system at an MLSS concentration of 4000 mg / L. The inoculation method adopted in this embodiment was direct injection of the culture solution containing the bacterial strain. The dissolved oxygen concentration was controlled to 3 mg / L by an aeration device, the hydraulic retention time (HRT) of the biological treatment system was set to 100 hours (starting from the time of inoculation of the microbial flora), and the reaction temperature was 30°C.

[0059] (2.3) Deep processing

[0060] After the dye intermediate wastewater in the biological treatment system is inoculated with microbial flora for a set time, it is sent to the membrane bioreactor (MBR) for deep treatment. The membrane component of the MBR uses a hollow fiber membrane (microfiltration membrane) with a pore size of 0.2μm. Under the operating pressure of 0.2MPa, the wastewater is further filtered to remove residual organic matter and microorganisms.

[0061] Table 1: Treatment results of wastewater with different concentrations in Example 1

[0062]

[0063] Table 1 proves that the biological treatment method for dye intermediate production wastewater provided in this embodiment can achieve a COD removal rate of more than 96%. The treated wastewater can meet strict discharge standards.

[0064] A small amount of biological sludge (sludge containing microorganisms, residual sludge) will be produced in the biological treatment process provided in this embodiment, and the sludge needs to be treated. The steps of sludge treatment include concentration, dehydration, drying, etc. After the moisture content of the sludge is reduced to a certain level, it is finally disposed of by incineration, landfill, etc. The sludge is concentrated by gravity concentration method, and the concentration time is 10-26h, which can effectively reduce the moisture content of the sludge. The sludge is dehydrated by a plate and frame filter press or a belt filter press. The moisture content of the dehydrated sludge is 60-85%, which can meet the final disposal requirements of the sludge.

[0065] Example 2

[0066] The biological treatment method of dye intermediate (metaphenylenediamine) production wastewater of the present invention is as follows: firstly, biological bacteria with high efficiency in degrading characteristic pollutants (metaphenylenediamine) of dye intermediate wastewater are screened from nature and domesticated and cultured, and then the biological bacteria are used to perform biological purification treatment on dye intermediate (metaphenylenediamine) wastewater; specifically, the following steps are included:

[0067] Step 1: Microbial screening and domestication

[0068] 15g of soil samples were collected from the dye intermediate (m-phenylenediamine) production workshop and the dye intermediate (m-phenylenediamine) wastewater discharge port, and added to conical flasks containing 100mL of enrichment medium. The components of the enrichment medium include: glucose, 1g / L; peptone, 0.6g / L; yeast extract, 0.4g / L; m-phenylenediamine, 0.1g / L; NH4Cl, 0.3g / L; K2HPO4, 0.3g / L; MgSO4·7H2O, 0.1g / L; HCl was used to adjust the pH value of the enrichment medium to 6.9.

[0069] The conical flask was placed in a shaker and cultured for 5 days at a temperature of 25°C ± 2 and a rotation speed of 300 r / min. Then 20 mL of the culture solution was transferred to a fresh enrichment medium and cultured 3-4 times to obtain a dominant microbial flora. The microbial flora was composed of a variety of microorganisms such as Bacillus and Pseudomonas (the bacterial count of Bacillus and Pseudomonas was about OD 415nm =0.4, the ratio of the two is 1:3). If the above steps fail, change the soil sampling location and repeat the above steps until the dominant microbial flora is successfully cultured.

[0070] The method for determining the successful cultivation of the dominant microbial flora and the method for determining the ratio of two different species (Bacillus and Pseudomonas) are the same as those in Example 1 and are not described in detail here. In this example, the type of characteristic pollutants added to the culture medium is different from that in Example 1, resulting in a different ratio of the dominant microbial flora screened out.

[0071] After culturing two different dominant microbial communities from two different soil samples, the same bacterial count ratio (OD 415nm =0.2, the ratio of the two is 1:1) and then they are co-cultured.

[0072] The microbial flora obtained in the above steps was expressed as OD 415nm =0.4 was inoculated into a culture medium containing different concentrations of dye intermediate (m-phenylenediamine). The initial concentration of m-phenylenediamine was 0.1 g / L, which was gradually increased to 1 g / L. The other components of the culture medium were the same as those of the enrichment medium, and the culture conditions were a temperature of 25°C, a pH value of 8.5, and dissolved oxygen of 4 mg / L. Each time the concentration of the dye intermediate (m-phenylenediamine) was increased, 2-3 generations of microorganisms were cultured until the microorganisms could grow stably at a concentration of 1 g / L dye intermediate (m-phenylenediamine). The domesticated microbial flora was obtained.

[0073] Step (ii) Biological treatment

[0074] Biological treatment processes such as Figure 1As shown: the dye intermediate wastewater first enters the pH adjustment device to adjust the pH value to 7.0, then enters the biological treatment system (this embodiment uses an activated sludge bioreactor) for biological treatment, and finally enters the membrane bioreactor (MBR) for deep treatment before meeting the discharge standards.

[0075] The specific operation steps of the biological treatment process are as follows:

[0076] (2.1) Take 1000L of dye intermediate wastewater, then add dilute hydrochloric acid or sodium hydroxide solution to the wastewater, adjust the pH to 7.0, inject it into the biological treatment system, and adjust the temperature to 25±2℃.

[0077] (2.2) The domesticated microbial flora obtained in step (1) is inoculated into the biological treatment system at an MLSS concentration of 4000 mg / L, and the inoculation method is direct injection of the culture solution containing the bacterial strain. The dissolved oxygen concentration is controlled to 3 mg / L by an aeration device, the hydraulic retention time (HRT) of the biological treatment system is set to 98 hours (starting from the time of inoculation of the microbial flora), and the reaction temperature is 28°C.

[0078] (2.3) Deep processing

[0079] After the dye intermediate wastewater in the biological treatment system is inoculated with microbial flora for a set time, it is sent to the membrane bioreactor (MBR) for deep treatment. The membrane component of the MBR uses a hollow fiber membrane (microfiltration membrane) with a pore size of 0.2μm. Under the operating pressure of 0.2MPa, the wastewater is further filtered to remove residual organic matter and microorganisms.

[0080] Table 2: Treatment results of wastewater with different concentrations in Example 2

[0081]

[0082] After the treatment in the above specific implementation method, the COD removal rate of dye intermediate production wastewater can reach more than 93%. The treated wastewater can meet strict discharge standards.

[0083] Example 3

[0084] The present invention discloses a biological treatment method for dye intermediate (p-nitroaniline) production wastewater as follows: firstly, a biological bacterium having high efficiency in degrading characteristic pollutants (p-nitroaniline) in dye intermediate wastewater is screened and cultivated, and then the biological bacterium is used to perform biological purification treatment on the dye intermediate wastewater; the method specifically comprises the following steps:

[0085] Step 1: Microbial screening and domestication

[0086] 20g of soil samples were collected from the dye intermediate (p-nitroaniline) production workshop and the dye intermediate (p-nitroaniline) wastewater discharge port, and added to conical flasks containing 100mL of enrichment medium. The components of the enrichment medium include: glucose, 1.6g / L; peptone, 1.0g / L; yeast extract, 0.5g / L; p-nitroaniline, 0.1g / L; KNO3, 0.5g / L; K2HPO4, 0.2g / L; MgSO4·7H2O, 0.2g / L; NaOH was used to adjust the pH value of the enrichment medium to 7.1.

[0087] The conical flask was placed in a shaker and cultured for 3 days at a temperature of 35°C and a rotation speed of 100 r / min. Then 15 mL of the culture solution was transferred to a fresh enrichment medium and cultured 3-4 times to obtain a dominant microbial flora. The microbial flora consisted of a variety of microorganisms such as Bacillus and Pseudomonas (the bacterial count of Bacillus and Pseudomonas was about OD 415nm =0.3, the ratio of the two is 1:2). If the above steps fail, change the soil sampling location and repeat the above steps until the dominant microbial flora is successfully cultured.

[0088] The method for determining whether the dominant microbial flora has been successfully cultured and the method for determining the ratio of two different bacterial species (Bacillus and Pseudomonas) are the same as those in Example 1 and are not described in detail herein.

[0089] After culturing two different dominant microbial communities from two different soil samples, the same bacterial count ratio (OD 415nm =0.2, the ratio of the two is 1:1) and then they are co-cultured.

[0090] The microbial flora obtained in the above steps was expressed as OD 415nm =0.3 was inoculated into a culture medium containing different concentrations of dye intermediate (p-nitroaniline). The initial dye intermediate concentration was 0.1 g / L, which was gradually increased to 1 g / L. The other components of the culture medium were the same as those of the enrichment medium, and the culture conditions were 35°C, pH 6.5, and dissolved oxygen 2 mg / L. Each time the p-nitroaniline concentration was increased, 2-3 generations of microorganisms were cultured until the microorganisms could grow stably at a concentration of 1 g / L dye intermediate (p-nitroaniline). The domesticated microbial flora was obtained.

[0091] Step (ii) Biological treatment

[0092] Biological treatment processes such as Figure 1As shown: the dye intermediate wastewater first enters the pH adjustment device to adjust the pH value to 7.0, then enters the biological treatment system (activated sludge bioreactor) for biological treatment, and finally enters the membrane bioreactor (MBR) for deep treatment before meeting the discharge standards.

[0093] The specific operation steps of the biological treatment process are as follows:

[0094] (2.1) Take 1000L of dye intermediate wastewater, add dilute hydrochloric acid or sodium hydroxide solution to the wastewater, adjust the pH to 9.0, inject it into the biological treatment system, and adjust the temperature to 20±2℃.

[0095] (2.2) The domesticated microbial flora obtained in step (1) is inoculated into the biological treatment system at an MLSS concentration of 8000 mg / L. The hydraulic retention time (HRT) of the biological treatment system is 92 hours (starting from the time of inoculation of the microbial flora), and the reaction temperature is 20±2°C. During the reaction, the dissolved oxygen concentration is controlled to be 5.9-6.1 mg / L by an aeration device.

[0096] (2.3) After the dye intermediate wastewater in the biological treatment system is inoculated with microbial flora for a set time, it enters the membrane bioreactor (MBR) for deep treatment. The membrane component of the MBR uses a hollow fiber membrane (microfiltration membrane) with a pore size of 0.2μm. Under an operating pressure of 0.3MPa, the wastewater is further filtered to remove residual organic matter and microorganisms.

[0097] Table 3: Treatment results of dye intermediate wastewater with different concentrations in Example 3

[0098]

[0099] After the treatment in the above specific implementation method, the COD removal rate of dye intermediate production wastewater can reach more than 90%. The treated wastewater can meet strict discharge standards.

[0100] The above display only describes the main features and inventive points of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above-mentioned embodiments. Without departing from the present invention and the scope of protection, the present invention may have various changes, and these changes and improvements will fall within the scope of protection claimed by the present invention. The scope of protection claimed by the present invention is limited by the attached claims and their equivalents.

Claims

1. A biological treatment method for dye intermediate production wastewater, characterized in that: Firstly, biological bacteria with high efficiency in degrading characteristic pollutants of dye intermediate wastewater are screened from nature and domesticated and cultured, and then the dye intermediate wastewater is subjected to biological purification treatment using the biological bacteria; The specific steps include: Step 1: Screening and domestication of biological bacteria; First, biological bacteria with the ability to degrade characteristic pollutants in dye intermediate wastewater are screened from the soil near the dye intermediate production environment, and the dominant microbial flora is obtained by multiple screening in an enrichment medium containing dye intermediates; Then, the screened dominant microbial flora is domesticated, and the domesticated microbial flora is inoculated into a culture medium with gradually increasing dye intermediate concentrations. After multiple generations of cultivation, the microorganisms are adapted to the high-concentration dye intermediate wastewater environment; the bacterial count OD inoculated into the culture medium with gradually increasing dye intermediate concentrations is 415nm =0.2-0.4, the culture conditions are temperature 25-35°C, pH 6.5-8.5, and dissolved oxygen controlled at 2-4 mg / L; Step 2: biological purification treatment; First, the dye intermediate wastewater is sent to the regulating tank to adjust the pH value of the wastewater to 6-9 and the temperature to 20-35°C to meet the requirements of subsequent biological treatment; Then, the conditioned wastewater is sent to a bioreactor for biological treatment, and the bioreactor is inoculated with a microbial flora that is screened and domesticated in step 1 and can efficiently degrade dye intermediate wastewater; the microbial flora includes Bacillus and Pseudomonas, and the amount of Bacillus and Pseudomonas inoculated is OD 415nm =0.2-0.4, the ratio of the two is 1:1-1:3; After biological treatment, the wastewater is further treated with a membrane bioreactor (MBR) to further remove residual organic matter and microorganisms in the wastewater.

2. The biological treatment method for dye intermediate production wastewater according to claim 1, characterized in that: The step 1, screening and domestication of biological bacteria, is specifically carried out in the following manner: Collect soil samples near the dye intermediate production workshop or the dye intermediate wastewater discharge outlet, and add them to a conical flask containing enrichment culture medium at a ratio of 0.1-0.2 g / mL; or collect soil samples near the dye intermediate production workshop and the dye intermediate wastewater discharge outlet, and add them to conical flasks containing enrichment culture medium at a ratio of 0.1-0.2 g / mL respectively; Place the conical flask in a shaker and culture for 3-5 days at a temperature of 25-35°C and a rotation speed of 100-200 r / min; then take a portion of the culture solution and transfer it to a fresh enrichment medium, repeat the culture 3-4 times to obtain a dominant microbial flora; The two different dominant microbial flora obtained from the two different soil samples were mixed at the same bacterial amount ratio and then co-cultured; The screened microbial flora was expressed as OD 415nm =0.2-0.4 is inoculated into a culture medium containing different concentrations of dye intermediates; the initial dye intermediate concentration is 0.1 g / L, which is gradually increased to 1 g / L; the other components of the culture medium are the same as those of the enrichment medium, the culture conditions are a temperature of 25-35°C, a pH value of 6.5-8.5, and dissolved oxygen is controlled at 2-4 mg / L; each time the dye intermediate concentration is increased, 2-3 generations of microorganisms are cultured until the microorganisms can stably grow at a dye intermediate concentration of 1 g / L.

3. The biological treatment method for dye intermediate production wastewater according to claim 2, characterized in that: The components of the enrichment medium include: Glucose: 0.8-1.6g / L Peptone: 0.5-1.0g / L Yeast extract: 0.3-0.5g / L Dye intermediate: 0.1g / L Salts: 0.3-0.8g / L K2HPO4: 0.2-0.3g / L MgSO4·7H2O:0.1-0.2g / L The pH value is 6.9-7.

1.

4. The biological treatment method for dye intermediate production wastewater according to claim 3, characterized in that: The dye intermediate is a combination of one or more of p-resorcinol, m-phenylenediamine and p-nitroaniline; the salt is a combination of one or more of KaCl, NaCl, NH4Cl and KNO3.

5. The biological treatment method for dye intermediate production wastewater according to claim 1, characterized in that: The biological reaction tank is an activated sludge biological reaction tank; In the activated sludge process bioreactor, the domesticated microbial flora is put into the bioreactor, the MLSS concentration of the mixed liquor is controlled at 3000-8000 mg / L, the hydraulic retention time HRT is 2-5 days, and the dissolved oxygen is controlled at 1.5-6 mg / L.

6. The biological treatment method for dye intermediate production wastewater according to claim 1, characterized in that: The bioreactor is a biofilm bioreactor. In the biofilm bioreactor, microorganisms are attached to the surface of the filler to form a biofilm. The specific surface area of ​​the filler is 100-240m 2 / m 3 , which can provide sufficient attachment area for microorganisms and promote their growth and reproduction; the hydraulic retention time HRT of wastewater in the biofilm biological reactor is 2-5 days, and the dissolved oxygen is controlled at 1.5-6 mg / L.

7. The biological treatment method for dye intermediate production wastewater according to claim 6, characterized in that: The filler is a porous composite filler; the porous composite filler is polyethylene or polypropylene.

8. The biological treatment method for dye intermediate production wastewater according to claim 1, characterized in that: The membrane component of MBR is a microfiltration membrane or an ultrafiltration membrane with a pore size of 0.01-0.4μm.

9. The biological treatment method for dye intermediate production wastewater according to claim 8, characterized in that: The small amount of sludge generated during the biological treatment process is incinerated or landfilled after the moisture content of the sludge is reduced to a certain level through sludge concentration, sludge dehydration and / or sludge drying treatment processes.

10. The biological treatment method for dye intermediate production wastewater according to claim 9, characterized in that: The sludge is concentrated by gravity concentration method, and the concentration time is 10-26h; the sludge is dehydrated by plate and frame filter press or belt filter press, and the moisture content of the dehydrated sludge is 60-85%.

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