A microbial treatment method for high nitrate nitrogen wastewater

Abstract

The present invention relates to the technical field of nitrate nitrogen wastewater treatment, and discloses a microbial treatment method for high nitrate nitrogen wastewater, comprising the following steps: adding a microbial carrier to a wastewater treatment device, and then inoculating denitrifying Paracoccus with a preservation number of CGMCC No.28691 ( Paracoccus denitrificans )392A9, and biofilm formation; the nitrate nitrogen content in the wastewater is controlled to be no higher than 11000 mg / L, the pH is controlled to be 5.0-8.0, and the wastewater is passed into the wastewater treatment device for microbial denitrification. The method of the present invention can effectively reduce the nitrate nitrogen concentration in high nitrate nitrogen wastewater, simplify the wastewater pretreatment process, reduce the amount of dilution water, and can achieve effective treatment of high nitrate nitrogen wastewater under both anaerobic and aerobic conditions.

Description

Technical Field

[0001] The invention relates to the technical field of nitrate nitrogen wastewater treatment, and in particular to a microbial treatment method for high nitrate nitrogen wastewater. Background Art

[0002] The industrial, agricultural and daily life emissions contain a large amount of nitrate nitrogen (NO3 - -N) wastewater will cause ecological and environmental problems such as regional water quality deterioration and eutrophication of water bodies, and nitrate nitrogen and nitrite nitrogen converted from it will also be toxic to humans and animals. Therefore, the wastewater needs to be denitrified before discharge to remove the nitrate nitrogen. The nitrate nitrogen content in wastewater generated by some pharmaceutical, photovoltaic, nitrogen fertilizer manufacturing and other industries is very high, far exceeding the standard of total nitrogen concentration of influent of general sewage treatment plants <50mg / L. It is difficult to effectively remove nitrate nitrogen using conventional methods, which brings great challenges to the treatment of high nitrate nitrogen wastewater.

[0003] The microbial method uses the denitrification effect of microorganisms to convert nitrate nitrogen in wastewater into nitrogen gas. It is one of the common methods for denitrification of nitrate nitrogen wastewater. Compared with physical and biological methods, it has the advantages of no secondary pollution, high treatment efficiency, and simple operation. At present, the microbial treatment method can achieve a good denitrification effect on low-concentration nitrate nitrogen wastewater, but it is limited by the nitrate nitrogen concentration that microorganisms can adapt to and effectively treat. When used for the treatment of high nitrate nitrogen wastewater, it is necessary to use a large amount of water to dilute the wastewater in advance, or reduce the nitrate nitrogen content through physical and chemical methods. The pretreatment process is relatively complicated and the cost is high. Summary of the invention

[0004] In order to solve the above technical problem, that is, when microbial methods are used to treat high nitrate nitrogen wastewater, the pretreatment process is relatively complicated and the cost is relatively high, the present invention provides a microbial treatment method for high nitrate nitrogen wastewater. The method can effectively reduce the nitrate nitrogen concentration in high nitrate nitrogen wastewater, simplify the wastewater pretreatment process, reduce the amount of dilution water, and can achieve effective treatment of high nitrate nitrogen wastewater under both anaerobic and aerobic conditions.

[0005] The specific technical scheme of the present invention is:

[0006] A microbial treatment method for high nitrate nitrogen wastewater comprises the following steps:

[0007] (1) adding the microbial carrier into a wastewater treatment device, inoculating Paracoccus denitrificans 392A9 with a deposit number of CGMCC No. 28691, and forming biofilm;

[0008] (2) The nitrate nitrogen content in the wastewater is controlled to be no higher than 11000 mg / L, the pH is controlled to be between 5.0 and 8.0, and the wastewater is passed into a wastewater treatment device for microbial denitrification.

[0009] The denitrifying Paracoccus 392A9 used in the above method has been deposited in the General Microbiology Center of the China Culture Collection Administration on October 20, 2023. The address of the depository is No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing. The deposit number is CGMCC No. 28691, and the microbial classification is named Paracoccus denitrificans.

[0010] Paracoccus denitrificans 392A9 can tolerate higher nitrate nitrogen concentrations and adapt to a wider pH range. It can survive and achieve efficient removal of nitrate nitrogen when the nitrate nitrogen concentration is not higher than 11000 mg / L and the pH is 5.0-8.0. Therefore, the present invention uses the strain to treat high nitrate nitrogen wastewater. When the nitrate nitrogen content in the wastewater is not higher than 11000 mg / L and the pH is 5.0-8.0, microbial denitrification can be directly performed without reducing the nitrate nitrogen content through pretreatment, and a better nitrate nitrogen removal effect can be achieved; when the nitrate nitrogen content in the wastewater is higher than 11000 mg / L or the pH is not within the range of 5.0-8.0, although it is necessary to reduce the nitrate nitrogen content to not higher than 11000 mg / L and adjust the pH to 5.0-8.0 through pretreatment, the pretreatment process can be simplified and the amount of dilution water and pH adjustment reagents can be reduced.

[0011] In addition, Paracoccus denitrifyingus 392A9 can tolerate high concentrations of nitrate nitrogen under both aerobic and anaerobic conditions and achieve efficient removal of nitrate nitrogen, so the requirement for dissolved oxygen content in wastewater is relatively low. Therefore, in the process of microbial denitrification, the present invention can flexibly select anaerobic and aerobic processes according to different needs, and there is no need to strictly control the dissolved oxygen content in the wastewater.

[0012] Preferably, in step (2), after adding nutrients to the wastewater, it is introduced into the wastewater treatment device; the nutrients include: KH2PO4, MgSO4, MnSO4, CaCl2, FeSO4, Na2MoO4, CuSO4, ZnSO4, CoCl2, H3BO3, recovery promoting factor (Rpf), and carbon source.

[0013] By adding the above nutrients, the activity of Paracoccus denitrifyingus 392A9 can be improved, thereby improving the removal efficiency of nitrate nitrogen in wastewater.

[0014] Preferably, the nutrients include KH2PO4, RM nutrient solution and a carbon source; the RM nutrient solution contains the following components: MgSO4, MnSO4, CaCl2, FeSO4, Na2MoO4, CuSO4, ZnSO4, CoCl2, H3BO3 and a recovery-promoting factor.

[0015] Preferably, the resuscitation promoting factor is extracted from Micrococcus luteus.

[0016] Preferably, the amount of KH2PO4 added to the wastewater is 0.4-0.7 g / L; the amount of RM nutrient solution added to the wastewater is 1-1.5 mL / L; the ratio of COD to nitrate nitrogen content added by the carbon source to the wastewater is 6.6-7.5:1.

[0017] Preferably, step (1) specifically comprises the following steps: adding the microbial carrier into the wastewater treatment device, then introducing debugging water with a nitrate nitrogen content of 450-550 mg / L, and then inoculating denitrifying Paracoccus 392A9, mixing, and completing biofilm formation when the nitrate nitrogen removal rate reaches 80% or above.

[0018] Preferably, the dosage of the microbial carrier is: 1 to 2 g of the microbial carrier per liter of effective volume of the wastewater treatment device.

[0019] Preferably, the denitrifying Paracoccus 392A9 is inoculated in the form of bacterial powder, and the amount of live bacteria in the bacterial powder is 1.5×10 10 ~2.6×10 10 cfu / g, the inoculation amount in the debugging water is 3-4g / L.

[0020] Preferably, the method for preparing the bacterial powder comprises the following steps:

[0021] (A) Paracoccus denitrificans 392A9 was inoculated on solid culture medium and cultured until a single colony grew;

[0022] (B) picking a single bacterial colony for seed culture to obtain seed liquid;

[0023] (C) inoculating the seed liquid into a fermentation medium to perform fermentation culture to obtain a bacterial liquid;

[0024] (D) Drying the bacterial solution to obtain bacterial powder.

[0025] Preferably, in step (A), the solid culture medium comprises components in the following concentrations: yeast extract 4-6 g / L, trypsin 8-13 g / L, NaCl 8-13 g / L, KNO3 1-3 g / L, and agar 15-20 g / L.

[0026] Preferably, step (B) specifically comprises the following steps: picking a single colony and inoculating it into a seed culture medium, culturing it at 25-30°C for 2-3 days to obtain a primary seed solution; inoculating the primary seed solution into the seed culture medium at an inoculation rate of 1-3%, culturing it at 25-30°C for 2-3 days to obtain a seed solution; the seed culture medium comprises the following components in the following concentrations: yeast extract 4-6 g / L, trypsin 8-13 g / L, NaCl 8-13 g / L, and KNO3 1-3 g / L.

[0027] Preferably, in step (C), the fermentation medium comprises components in the following concentrations: yeast extract 4-6 g / L, trypsin 8-13 g / L, NaCl 8-13 g / L, KNO3 1-3 g / L; the fermentation culture temperature is 25-30°C, the dissolved oxygen content in the fermentation medium is 2-5 mg / L, the pH is 7-8, and the fermentation time is 36-48 h.

[0028] Preferably, in step (2), during the microbial denitrification treatment, the water temperature in the wastewater treatment device is controlled at 25-30°C.

[0029] Preferably, in step (2), when the nitrate nitrogen content in the wastewater is higher than 11000 mg / L, wastewater with a nitrate nitrogen content lower than 11000 mg / L is used for dilution.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] (1) In the process of treating high nitrate nitrogen wastewater, the present invention adopts a new strain Paracoccus denitrificans 392A9, which can adapt to higher nitrate nitrogen concentrations and a wider pH range, and can achieve efficient removal of nitrate nitrogen under both aerobic and anaerobic conditions. However, at present, within the species to which this strain belongs (Paracoccus denitrificans), there has been no report of any strain that has tolerance and treatment capabilities for high concentrations of nitrate nitrogen that can reach a level comparable to that of strain 392A9.

[0032] (2) The present invention can improve the activity of Paracoccus denitrifyingus 392A9 by pre-adding specific nutrients to the wastewater, thereby improving the nitrate nitrogen removal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the effect of influent pH on the aerobic denitrification effect of strain 392A9.

[0034] Figure 2 This is the aerobic continuous water inlet and outlet test device used in Example 2.

[0035] Figure 3This is the effect of the amount of glucose added to the influent on the aerobic denitrification effect of strain 392A9.

[0036] Figure 4 This is the effect of HRT on the aerobic denitrification effect of strain 392A9.

[0037] Figure 5 This is the anaerobic continuous water inlet and outlet test device used in Example 3.

[0038] Figure 6 This is the effect of influent pH on the anaerobic nitrogen removal effect of strain 392A9.

[0039] Figure 7 This is the effect of the amount of glucose added to the influent on the anaerobic denitrification effect of strain 392A9.

[0040] Figure 8 This is the effect of HRT on the anaerobic nitrogen removal effect of strain 392A9. DETAILED DESCRIPTION

[0041] The present invention will be further described below in conjunction with the embodiments.

[0042] Overall embodiment

[0043] A microbial treatment method for high nitrate nitrogen wastewater comprises the following steps:

[0044] (1) adding the microbial carrier into a wastewater treatment device, inoculating Paracoccus denitrificans 392A9 with a deposit number of CGMCC No. 28691, and forming biofilm;

[0045] (2) The nitrate nitrogen content in the wastewater is controlled to be no higher than 11000 mg / L, the pH is controlled to be between 5.0 and 8.0, and the wastewater is passed into a wastewater treatment device for microbial denitrification.

[0046] As a specific implementation method, in step (2), after adding nutrients to the wastewater, it is then introduced into a wastewater treatment device; the nutrients include: KH2PO4, MgSO4, MnSO4, CaCl2, FeSO4, Na2MoO4, CuSO4, ZnSO4, CoCl2, H3BO3, recovery promoting factors, and carbon sources.

[0047] As a specific implementation manner, the nutrients include KH2PO4, RM nutrient solution and carbon source; the RM nutrient solution contains the following components: MgSO4, MnSO4, CaCl2, FeSO4, Na2MoO4, CuSO4, ZnSO4, CoCl2, H3BO3, and recovery promoting factor; the amount of KH2PO4 added to the wastewater is 0.4-0.7 g / L; the amount of RM nutrient solution added to the wastewater is 1-1.5 mL / L; the ratio of COD to nitrate nitrogen content added by the carbon source to the wastewater is 6.6-7.5:1.

[0048] As a specific implementation method, step (1) specifically includes the following steps: adding the microbial carrier to the wastewater treatment device, then introducing debugging water with a nitrate nitrogen content of 450-550 mg / L, and then inoculating denitrifying Paracoccus 392A9, mixing, and completing biofilm formation when the nitrate nitrogen removal rate reaches 80% or above.

[0049] As a specific implementation manner, the dosage of the microbial carrier is: 1 to 2 g of the microbial carrier per liter of effective volume of the wastewater treatment device.

[0050] As a specific embodiment, the denitrifying Paracoccus 392A9 is inoculated in the form of bacterial powder, and the amount of live bacteria in the bacterial powder is 1.5×10 10 ~2.6×10 10 cfu / g, the inoculation amount in the debugging water is 3-4g / L.

[0051] As a specific implementation, the method for preparing the bacterial powder comprises the following steps:

[0052] (A) Paracoccus denitrificans 392A9 was inoculated on solid culture medium and cultured until a single colony grew;

[0053] (B) picking a single bacterial colony for seed culture to obtain seed liquid;

[0054] (C) inoculating the seed liquid into a fermentation medium to perform fermentation culture to obtain a bacterial liquid;

[0055] (D) Drying the bacterial solution to obtain bacterial powder.

[0056] As a specific embodiment, in step (A), the solid culture medium includes components with the following concentrations: yeast extract 4-6 g / L, trypsin 8-13 g / L, NaCl 8-13 g / L, KNO3 1-3 g / L, and agar 15-20 g / L.

[0057] As a specific implementation method, step (B) specifically includes the following steps: picking a single colony and inoculating it into a seed culture medium, culturing it at 25-30°C for 2-3 days to obtain a primary seed solution; inoculating the primary seed solution into the seed culture medium at an inoculation rate of 1-3%, culturing it at 25-30°C for 2-3 days to obtain a seed solution; the seed culture medium includes the following components in the following concentrations: yeast extract 4-6 g / L, trypsin 8-13 g / L, NaCl 8-13 g / L, and KNO3 1-3 g / L.

[0058] As a specific embodiment, in step (C), the fermentation medium includes components with the following concentrations: yeast extract 4-6 g / L, trypsin 8-13 g / L, NaCl 8-13 g / L, KNO3 1-3 g / L; the fermentation culture temperature is 25-30°C, the dissolved oxygen content in the fermentation medium is 2-5 mg / L, the pH is 7-8, and the time is 36-48 h.

[0059] As a specific implementation, in step (2), when the nitrate nitrogen content in the wastewater is higher than 11000 mg / L, wastewater with a nitrate nitrogen content lower than 11000 mg / L is used for dilution.

[0060] As a specific implementation, in step (2), during the microbial denitrification treatment, the water temperature in the wastewater treatment device is controlled to be 25-30°C. Specific embodiments

[0062] The present invention is described below by means of specific examples. It should be understood that these examples are intended to further introduce and demonstrate the purpose, technical scheme and technical effect of the present invention, and are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0063] The strain 392A9 described in the following examples all refers to Paracoccus denitrificans 392A9 with a deposit number of CGMCC No.28691.

[0064] The medium preparation method used in the following examples is as follows:

[0065] (1) Wastewater culture medium:

[0066] The source of the wastewater is high nitrate wastewater from a new material in Hubei, the main component of which is sodium nitrate. The quality of the wastewater is shown in Table 1. KH2PO4 0.5 g / L was added to the wastewater, and the pH was adjusted to 7.0 with NaOH to obtain the prepared wastewater.

[0067] Table 1 Water quality of high nitrate wastewater

[0068] index unit Numeric COD mg / L 80364 TOC mg / L 41391 <![CDATA[NH3-N]]> mg / L 0 TP mg / L 5 <![CDATA[NO2 - -N]]> mg / L 0 <![CDATA[NO3 - -N]]> mg / L 10000 TN mg / L 10000 TDS ％ 1.20 pH / 5

[0069] Wastewater liquid culture medium: prepared by filtering and sterilizing the prepared wastewater using a sterile 0.22 μm filter membrane.

[0070] Wastewater solid culture medium: The prepared wastewater was filtered and sterilized with a sterile 0.22μm filter membrane to obtain solution A; 4% agar solution was prepared with distilled water and sterilized at 121℃ for 20min to obtain solution B. The mixture was mixed at a ratio of solution A: solution B = 1:1 (v / v) and then introduced into a sterile culture dish to obtain a wastewater solid separation medium.

[0071] (2) LB medium:

[0072] Yeast extract 5g / L, tryptone 10g / L, NaCl 10g / L, solvent is water; pH natural. Sterilized at 121℃ for 20min.

[0073] (3) RM nutrient solution:

[0074] Rpf crude solution 10mL, MgSO4·7H2O 0.3g / L, MnSO4·H2O 0.2g / L, CaCl2 0.2g / L, FeSO4·7H2O 0.2g / L, Na2MoO4·2H2O 0.008g / L, CuSO4·5H2O 0.006g / L, ZnSO4·7H2O 0.009g / L, CoCl2·6H2O0.0001g / L, H3BO3 0.015g / L; pH = 6. The preparation method of Rpf crude solution can be found in patent ZL202211094469.7 A composite for promoting the separation and cultivation of anaerobic microorganisms and its application.

[0075] (4) Strain fermentation medium (SNM):

[0076] SNM liquid medium: 5 g / L yeast extract, 10 g / L tryptone, 10 g / L NaCl, 2 g / L KNO3, water as solvent; pH 7.0. Sterilized at 121°C for 20 min.

[0077] SNM solid medium: Add 20 g / L agar to SNM liquid medium and sterilize at 121°C for 20 min.

[0078] Example 1: Screening and identification of strains

[0079] 1.1 Preliminary screening of bacterial strains

[0080] The strains are derived from a pharmaceutical and chemical source strain library (containing more than 6,000 strains) accumulated by the team of the present invention through long-term scientific research. The strains in the library are all isolated from pharmaceutical and chemical related samples (such as wastewater, soil, PBR biological pretreatment system, activated sludge system, etc.).

[0081] According to the characteristics of wastewater and the source of strain isolation, 2000 strains of bacteria were selected from the library for screening. The strains were activated using a 96-well plate filled with LB medium. After culturing for 2 days, each bacterial solution was inoculated at a 1% inoculum into a wastewater liquid medium (containing NO3 - -N 5000mg / L) in a 96-well plate, the system was placed in a micro-oscillator and cultured at 30°C. The OD within 3 days was selected using an enzyme marker. 600 >0.5 to screen strains with high nitrate resistance, which were used as re-screening strain I.

[0082] Results: A total of 8 strains of rescreened strain I were obtained.

[0083] 1.2 Strain rescreening

[0084] After the above-mentioned rescreened strain I was activated in LB medium for 2 days, each bacterial solution was inoculated at a 1% inoculum into 3 mL of liquid medium containing 4-fold diluted wastewater (containing NO3 - -N 2500mg / L) in a test tube, the system was incubated at 150r / min and 30℃, and the NO3 in the system was evaluated using nitrate nitrogen test paper. - -N content, select the system NO3 within 5 days - -N removal rate ≥ 50%, and repeatedly streaked the strains on wastewater solid culture medium to obtain strains that grow stably on wastewater as re-screening strain II.

[0085] Results: One strain of rescreening II was obtained, named 392A9.

[0086] 1.3 Strain identification

[0087] The genomic DNA of strain 392A9 was extracted using a genome extraction kit, and 16SrDNA was amplified by PCR and sequenced for molecular biological identification. The upstream primer and downstream primer used in PCR amplification were:

[0088] Upstream primer 27F: 5'-GAGAGTTTGATCMTGGCTCAG-3'

[0089] Downstream primer 1492R: 5′-TACGGYTACCTTGTTACGAC-3′

[0090] The purification and sequencing of PCR products were completed by Shanghai Bioengineering. The obtained 16S rDNA sequence of the strain was compared in the EzBioCloud database. The results showed that the strain belonged to Paracoccus denitrificans, so it was named: Paracoccus denitrificans 392A9.

[0091] Example 2: Denitrification effect of strain 392A9 under aerobic conditions (small test)

[0092] 2.1 Test apparatus

[0093] The test device is a continuous water inlet and outlet device, which simulates the on-site treatment system to the greatest extent possible to test the treatment effect of the bacteria on high nitrate wastewater. Figure 2 As shown in the figure, it consists of an inlet pool, a strain pool and an outlet pool connected in sequence. The effective volume of each pool is 3L. The inlet pool is used to supplement nutrients and accommodate wastewater, and a stirring system is installed at the bottom. The strain treatment pool is a strain biochemical treatment pool, and an aeration system is installed at the bottom. The wastewater in the inlet pool is lifted to the strain pool by a peristaltic pump; the outlet pool is used to collect the treated wastewater.

[0094] 2.2 Water Intake

[0095] The source of the wastewater is high nitrate wastewater from a new material in Hubei, the main component of which is sodium nitrate. The wastewater quality is shown in Table 1 above. KH2PO4 0.5g / L, RM nutrient solution 1mL / L and a certain amount of glucose were added and adjusted to a certain pH as the influent.

[0096] 2.3 Adding bacteria

[0097] The strain 392A9 was cultured on LB solid medium at 30°C for 2 days, a single colony was picked and inoculated into LB liquid medium, and cultured at 150 r / min and 30°C until the logarithmic phase to obtain the seed solution of the strain 392A9.

[0098] Add 1 mL / L of RM nutrient solution to the bacterial seed pool, adjust the starting pH of the bacterial seed pool system to 7.0, and inoculate the seed solution of strain 392A9 into the bacterial seed treatment pool at an inoculation rate of 10%.

[0099] 2.4 Effect of influent pH on aerobic denitrification

[0100] No additional glucose was added to the influent, the DO of the bacterial pool was controlled to be ≥2.0 mg / L, the water temperature was 25-30 °C, the influent pH was set to 5.0, 6.0, 7.0, 8.0, and 9.0, respectively, and the effect of the bacterial strains on wastewater treatment within 10 days of HRT in the bacterial pool was checked. The results are shown in Figure 1 . Figure 1 In the above, denitrification rate is the TN removal rate.

[0101] The results showed that when the influent pH was adjusted to 5.0-6.0, the denitrification rate reached 50%, and then as the influent pH increased, the denitrification rate gradually decreased. The reason is speculated to be that during the aerobic denitrification reaction stage, the pH of the bacterial pool system showed an upward trend. The higher the influent pH, the higher the pH of the bacterial pool system. For example, when the influent pH was 5.0, the pH of the bacterial pool finally stabilized at around 9.0; and when the influent pH was 9.0, the pH of the bacterial pool system was as high as 11.0. The ultra-high pH of the system inhibited the growth and metabolism of the bacteria.

[0102] Conclusion: Strain 392A9 can perform aerobic denitrification in the influent pH range of 5.0-9.0. The influent pH should be controlled in the range of 5.0-6.0, with the optimum being 5.0.

[0103] 2.5 Effect of carbon source dosage on aerobic denitrification effect

[0104] The influent pH was adjusted to 5.0, the DO of the bacterial pool was controlled to be ≥2.0 mg / L, the water temperature was 25-30 °C, the influent glucose addition was set to 0, 5 g / L, 10 g / L, and 15 g / L, and the treatment effect of the bacterial pool HRT 10 days on the wastewater was checked. The results are shown in Figure 3 . Figure 3 In the above, denitrification rate is the TN removal rate.

[0105] The results showed that when glucose was added to the influent, the denitrification rate was significantly promoted. As the amount of glucose gradually increased, the denitrification rate also increased. However, when the amount of glucose added was 15-20g / L, the denitrification rate reached a maximum of about 99.5%.

[0106] Conclusion: Strain 392A9 can perform aerobic denitrification without the addition of glucose. The addition of glucose can improve its denitrification effect. The amount of glucose added in the influent should be controlled at 15-20 g / L, with the optimal amount being 15 g / L.

[0107] 2.6 Effect of HRT on aerobic denitrification

[0108] The influent pH was adjusted to 5.0, and 15 g / L of glucose was added. The DO of the bacterial pool was controlled to be ≥ 2.0 mg / L and the water temperature was 25-30 °C. The effects of different bacterial pool HRTs (5d, 6d, 7d, 8d, 9d, 10d) on the bacterial treatment effect were examined. The results are shown in the table. Figure 4 . Figure 4 In the above, denitrification rate is the TN removal rate.

[0109] The results showed that when the HRT was in the range of 5 to 10 days, the denitrification rate gradually increased with the extension of HRT, and reached the maximum denitrification rate of 99.5% at HRT 9 days.

[0110] Conclusion: The optimal HRT of strain 392A9 for aerobic denitrification is 9 days.

[0111] 2.7 Effect of aerobic wastewater treatment under optimal conditions

[0112] The influent pH was adjusted to 5.0, and 15 g / L of glucose was added. The DO of the strain pool was controlled to be ≥ 2.0 mg / L and the water temperature was 25-30 °C. The treatment effect of the strains in the strain pool HRT 9d on wastewater was checked. The results are shown in Table 2.

[0113] Table 2 Effect of strain 392A9 on aerobic treatment of high nitrate wastewater

[0114] Water Intake Water Removal rate Volumetric load HRT unit mg / L mg / L ％ <![CDATA[kg / (m 3 ·d)]]> d COD 98567 9810 90.0 9.9 9 TOC 54754 5436 90.1 5.5 9 <![CDATA[NO3 - -N]]> 10000 55 99.5 1.1 9 TN 10000 55 99.5 1.1 9

[0115] Note: In Table 2, the wastewater influent COD and TOC are the data after adding glucose.

[0116] The results showed that strain 392A9 could directly treat wastewater with a nitrate nitrogen concentration of 10,000 mg / L, and achieve a denitrification rate of 99.5% at HRT9d, with a denitrification volumetric load of 1.1 kg / (m 3 ·d) and simultaneously achieve efficient removal of wastewater COD and TOC, with a removal rate of about 90%. During aerobic denitrification, the required TOC / TN is about 5.0 and COD / TN is about 8.9.

[0117] Example 3: Denitrification effect of strain 392A9 under anaerobic conditions (small test)

[0118] 3.1 Test apparatus

[0119] The test device is a continuous water inlet and outlet device, which simulates the on-site treatment system to the greatest extent possible to test the treatment effect of the bacteria on high nitrate wastewater. Figure 5 As shown in the figure, it consists of an inlet pool, a strain pool and an outlet pool connected in sequence. The effective volume of each pool is 3L. The inlet pool is used to supplement nutrients and accommodate wastewater, and a stirring system is installed at the bottom. The strain treatment pool is a strain biochemical treatment pool, and a stirring system is installed at the bottom. The wastewater in the inlet pool is lifted to the strain pool by a peristaltic pump; the outlet pool is used to collect the treated wastewater.

[0120] 3.2 Water Intake

[0121] Same as Example 2.

[0122] 3.3 Adding bacteria

[0123] Same as Example 2.

[0124] 3.4 Effect of influent pH on anaerobic denitrification effect

[0125] No additional glucose was added to the influent, the DO of the bacterial pool was controlled to be ≤0.5 mg / L, the water temperature was 25-30 °C, the influent pH was set to 5.0, 6.0, 7.0, 8.0, and 9.0, respectively, and the effect of the bacterial strains on wastewater treatment within 10 days of HRT in the bacterial pool was checked. The results are shown in Figure 6 . Figure 6 In the above, denitrification rate is the TN removal rate.

[0126] The results showed that when the influent pH was adjusted to 6.0-7.0, the denitrification rate reached 50%, and the pH of the bacterial pool system was stable at around 9.0, while when the influent pH was lower or higher, the denitrification rate decreased. The reason is speculated: During the anaerobic denitrification reaction stage, when the influent pH was 5.0, the pH of the bacterial pool finally stabilized at around 7.5; and when the influent pH was 8.0-9.0, the pH of the bacterial pool system was as high as 10.0, and the ultra-high pH of the system inhibited the growth and metabolism of the bacteria.

[0127] Conclusion: Strain 392A9 can perform anaerobic denitrification in the influent pH range of 5.0-9.0. The influent pH should be controlled at 6.0-7.0, with the optimum being 6.0.

[0128] 3.5 Effect of carbon source dosage on anaerobic nitrogen removal effect

[0129] The influent pH was adjusted to 6.0, the DO of the bacterial pool was controlled to be ≤0.5mg / L, the water temperature was 25-30℃, the influent glucose addition amount was set to 0, 1g / L, 3g / L, 5g / L, 10g / L, and the treatment effect of the bacterial pool HRT 10d on the wastewater was checked. The results are shown in Figure 7 . Figure 7 In the above, denitrification rate is the TN removal rate.

[0130] The results showed that when glucose was added to the influent, the denitrification rate was significantly promoted, but when the glucose addition amount was 3-10g / L, the denitrification rate reached a maximum of about 65%.

[0131] Conclusion: Strain 392A9 can perform anaerobic denitrification without the addition of glucose. The addition of glucose can improve its denitrification effect. The amount of glucose added in the influent should be controlled at 3-10 g / L, with the optimal amount being 3 g / L.

[0132] 3.6 Effect of HRT on anaerobic denitrification

[0133] The influent pH was adjusted to 6.0, and 3 g / L of glucose was added. The DO of the bacterial pool was controlled to be ≤ 0.5 mg / L and the water temperature was 25-30 °C. The effects of different bacterial pool HRTs (5d, 10d, 15d, 20d) on the bacterial treatment effect were examined. The results are shown in the table. Figure 8 . Figure 8 In the above, denitrification rate is the TN removal rate.

[0134] The results showed that when the HRT was between 5 and 10 days, the denitrification rate gradually increased with the extension of HRT. When the HRT was 5 days, the denitrification rate was only 22.2%; when the HRT was 15 days, the maximum denitrification rate reached 98.9%. If the HRT was extended further, the denitrification rate would not increase any more.

[0135] Conclusion: The optimal HRT of strain 392A9 for anaerobic denitrification is 15 days.

[0136] 3.7 Effect of anaerobic wastewater treatment under optimal conditions

[0137] The influent pH was adjusted to 6.0, and 3 g / L of glucose was added. The DO of the strain pool was controlled to be ≤ 0.5 mg / L and the water temperature was 25-30 °C. The treatment effect of the strains in the strain pool HRT 15d on wastewater was checked. The results are shown in Table 3.

[0138] Table 3 Effect of strain 392A9 on anaerobic treatment of high nitrate wastewater

[0139] Water Intake Water Removal rate Volumetric load HRT unit mg / L mg / L ％ <![CDATA[kg / (m 3 ·d)]]> d COD 85364 20410 76.1 4.3 15 TOC 42796 9365 78.1 2.2 15 <![CDATA[NO3 - -N]]> 10000 106 98.9 0.7 15 TN 10000 106 98.9 0.7 15

[0140] Note: In Table 3, the wastewater influent COD and TOC are the data after adding glucose.

[0141] The results showed that strain 392A9 could directly treat wastewater with nitrate nitrogen content of 10,000 mg / L, and achieved a denitrification rate of 98.9% and a denitrification volumetric load of 0.7 kg / (m 3 ·d) and simultaneously achieve efficient removal of wastewater COD and TOC, with a removal rate of more than 75%. During anaerobic denitrification, the required TOC / TN is about 3.4 and COD / TN is about 6.6.

[0142] Example 4: Anaerobic denitrification process

[0143] 4.1 Wastewater quality

[0144] High-concentration wastewater is high-nitrate nitrogen wastewater, and low-concentration wastewater is low-nitrate nitrogen wastewater. The water quality of the two is shown in Table 4.

[0145] Table 4 Water quality of high-concentration wastewater and low-concentration wastewater

[0146]

[0147]

[0148] 4.2 Wastewater preparation

[0149] 4.2.1 Initial deployment

[0150] The initial preparation is carried out according to the nitrate nitrogen concentration of the wastewater. The high-concentration wastewater: low-concentration wastewater = 1:1 (v / v, i.e., water volume ratio) is mixed to obtain mixed wastewater, the water quality of which is shown in Table 5.

[0151] Table 5 Water quality of mixed wastewater

[0152] index unit Numeric COD mg / L 37662 TOC mg / L 13645 <![CDATA[NH3-N]]> mg / L 152 TP mg / L 23 <![CDATA[NO2 - -N]]> mg / L 27 <![CDATA[NO3 - -N]]> mg / L 10726 TN mg / L 13383 TDS ％ 1.90 pH / 9

[0153] 4.2.2 Re-deployment

[0154] The second step is to adjust the nutrition and pH. Add 0.5g / L KH2PO4 and 1mL / L RM nutrient solution to the mixed wastewater, supplement glucose according to COD / nitrate nitrogen = 6.6, about 30g / L glucose, and adjust the wastewater pH to 6.0-6.5 with H2SO4.

[0155] 4.3 Bacteria fermentation production

[0156] The strain 392A9 was streaked on a SNM solid culture medium plate and cultured at 30°C for 2 days. A single colony was picked out and placed in 3 mL of SNM liquid culture medium and cultured at 150 rpm and 30°C for 2 days to prepare a primary seed solution.

[0157] Then, the first-level seed solution was inoculated into 300 mL of SNM liquid culture medium at a 1% inoculation amount, and cultured at 150 rpm and 30° C. for 2 days to obtain the second-level seed solution.

[0158] The secondary seed liquid was fermented in a 50L fermentation tank, and the fermentation conditions were as follows: the bacterial inoculation amount was 1%, the fermentation medium was SNM liquid medium, the temperature was controlled at 25-30°C, the DO was controlled at 2-5mg / L, the pH was controlled at 7-8 (pH was adjusted by H2SO4 and NaOH), and the fermentation time was 36h to obtain bacterial liquid.

[0159] The bacterial liquid was prepared into bacterial powder by vacuum freeze drying, and the live bacterial count of the bacterial powder was 1.5×10 10 cfu / g.

[0160] 4.4 Initial commissioning

[0161] The device used in this example is an enlarged version of the pilot device in Example 3, and the effective volume of each tank is 180 L. Granular activated carbon is added to the bacterial pool as a microbial carrier, and the amount of granular activated carbon added is 1.5 g / L (i.e., 1.5 g of granular activated carbon is added per liter of effective volume).

[0162] The bacterial pool is treated by anaerobic process. The initial state of the bacterial pool is to add debugging water (mixed wastewater is diluted to a nitrate nitrogen concentration of 536mg / L, and RM nutrient solution is supplemented with 1mL / L), adjust the starting pH of the bacterial pool system to 7.0, and the temperature is about 30℃, and inoculate the bacterial powder in the bacterial pool according to the inoculation amount of 3g / L (that is, 3g of bacterial powder is inoculated in every liter of debugging water), stir, so that the initial system and bacterial powder are stirred evenly, and when the nitrate nitrogen removal rate of the initial system reaches 80% and the bacterial activity is good, the initial debugging of the bacterial pool is considered to be completed.

[0163] 4.5 Operating condition control

[0164] Influent: The influent is the wastewater after re-adjustment. During operation, the pH of the influent is controlled at 6.0-6.5.

[0165] Bacteria pool: During operation, DO is controlled at <0.5mg / L, water temperature is 25-30℃, and the HRT of wastewater in the bacteria pool is 10d.

[0166] 4.6 Wastewater treatment effect

[0167] The treatment effect of nitrate nitrogen in wastewater is shown in Table 6. By adopting the method of this embodiment, direct microbial anaerobic treatment of wastewater with nitrate nitrogen of 10726 mg / L can be achieved, and at HRT 10d, the nitrate nitrogen removal rate can reach 98.8%, and the nitrate nitrogen treatment volume load can reach 1.1 kg / (m 3 ·d).

[0168] Table 6 Anaerobic nitrate removal effect

[0169] Water Intake Water Removal rate Volumetric load HRT unit mg / L mg / L ％ <![CDATA[kg / (m 3 ·d)]]> d <![CDATA[NO3 - -N]]> 10726 123 98.8 1.1 10

[0170] Example 5: Aerobic denitrification process

[0171] 5.1 Wastewater quality

[0172] Same as Example 4.

[0173] 5.2 Wastewater preparation

[0174] Same as Example 4.

[0175] 5.3 Bacteria fermentation production

[0176] Same as Example 4.

[0177] 5.4 Initial commissioning

[0178] The device used in this example is an enlarged version of the pilot device in Example 2, and the effective volume of each tank is 180 L. Granular activated carbon is added to the bacterial pool as a microbial carrier, and the amount of granular activated carbon added is 1.5 g / L (i.e., 1.5 g of granular activated carbon is added per liter of effective volume).

[0179] The bacterial pool is treated by anaerobic process. The initial state of the bacterial pool is to add debugging water (mixed wastewater is diluted to a nitrate nitrogen concentration of 536mg / L, and RM nutrient solution is supplemented with 1mL / L), adjust the starting pH of the bacterial pool system to 7.0, and the temperature is about 30℃, and inoculate the bacterial powder in the bacterial pool according to the inoculation amount of 3g / L (that is, 3g of bacterial powder is inoculated in every liter of debugging water), stir, so that the initial system and bacterial powder are stirred evenly, and when the nitrate nitrogen removal rate of the initial system reaches 80% and the bacterial activity is good, the initial debugging of the bacterial pool is considered to be completed.

[0180] 5.5 Operating Condition Control

[0181] Influent: The influent is the wastewater after re-adjustment. During operation, the pH of the influent is controlled at 6.0-6.5.

[0182] Bacteria pool: During operation, DO is controlled at ≥2.0 mg / L, the water temperature is 25-30°C, and the HRT of wastewater in the bacteria pool is 10 days.

[0183] 5.6 Wastewater treatment effect

[0184] The treatment effect of nitrate nitrogen in wastewater is shown in Table 7. By adopting the method of this embodiment, direct microbial aerobic treatment of wastewater with nitrate nitrogen of 10726 mg / L can be achieved, and at HRT 6d, the nitrate nitrogen removal rate can reach 98.4%, and the nitrate nitrogen treatment volume load can reach 1.8 kg / (m 3 ·d).

[0185] Table 7 Aerobic nitrate removal effect

[0186] Water Intake Water Removal rate Volumetric load HRT unit mg / L mg / L ％ <![CDATA[kg / (m 3 ·d)]]> d <![CDATA[NO3 - -N]]> 10726 102 98.4 1.8 6

[0187] Unless otherwise defined, all technical terms and scientific terms used in the present invention have the same meanings as those commonly understood by ordinary technicians in the field to which the present disclosure belongs. Unless otherwise specified, the raw materials and equipment used in the present invention are conventional raw materials and equipment in the field and can be obtained from conventional commercial channels; unless otherwise specified, the methods used in the present invention are conventional methods in the field.

[0188] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A microbial treatment method for high nitrate nitrogen wastewater, characterized in that: The following steps are involved: (1) Add the microbial carrier to the wastewater treatment device and then inoculate the denitrifying Paracoccus with the deposit number of CGMCC No.28691 ( Paracoccus denitrificans ) 392A9, and carry out film formation; (2) The nitrate nitrogen content in the wastewater is controlled at 10,000-11,000 mg / L and the pH is controlled at 5.0-8.

0. The wastewater is then passed into the wastewater treatment device for microbial denitrification.

2. The microbial treatment method according to claim 1, characterized in that: In step (2), after adding nutrients to the wastewater, it is then introduced into the wastewater treatment device; the nutrients include: KH2PO4, MgSO4, MnSO4, CaCl2, FeSO4, Na2MoO4, CuSO4, ZnSO4, CoCl2, H3BO3, recovery promoting factor, and carbon source.

3. The microbial treatment method according to claim 1, characterized in that: Step (1) specifically includes the following steps: adding the microbial carrier to the wastewater treatment device, then introducing debugging water with a nitrate nitrogen content of 450-550 mg / L, and then inoculating denitrifying Paracoccus 392A9, mixing, and completing biofilm formation when the nitrate nitrogen removal rate reaches 80% or above.

4. The microbial treatment method according to claim 3, characterized in that: The dosage of the microbial carrier is: 1-2 g of the microbial carrier per liter of effective volume of the wastewater treatment device.

5. The microbial treatment method according to claim 3, characterized in that: The denitrifying Paracoccus 392A9 was inoculated in the form of bacterial powder, and the amount of live bacteria in the bacterial powder was 1.5×10 10 ~2.6×10 10 cfu / g, the inoculation amount in the debugging water is 3~4g / L.

6. The microbial treatment method according to claim 5, characterized in that: The preparation method of the bacterial powder comprises the following steps: (A) Paracoccus denitrificans 392A9 was inoculated on solid culture medium and cultured until a single colony grew; (B) Pick a single colony for seed culture to obtain seed liquid; (C) inoculating the seed liquid into a fermentation medium to perform fermentation culture to obtain a bacterial liquid; (D) Drying the bacterial liquid and grinding it into powder to obtain bacterial powder.

7. The microbial treatment method according to claim 6, characterized in that: In step (A), the solid culture medium comprises the following components in concentrations: 4-6 g / L yeast extract, 8-13 g / L tryptone, 8-13 g / L NaCl, 1-3 g / L KNO3, and 15-20 g / L agar.

8. The microbial treatment method according to claim 6, characterized in that: Step (B) specifically includes the following steps: picking a single colony and inoculating it into a seed culture medium, culturing it at 25-30°C for 2-3 days to obtain a primary seed solution; inoculating the primary seed solution into the seed culture medium at an inoculum amount of 1-3%, culturing it at 25-30°C for 2-3 days to obtain a seed solution; the seed culture medium includes the following components in the following concentrations: yeast extract 4-6 g / L, trypsin 8-13 g / L, NaCl 8-13 g / L, and KNO3 1-3 g / L.

9. The microbial treatment method according to claim 6, characterized in that: In step (C), the fermentation medium includes components with the following concentrations: yeast extract 4-6 g / L, trypsin 8-13 g / L, NaCl 8-13 g / L, KNO3 1-3 g / L; the fermentation culture temperature is 25-30°C, the dissolved oxygen content in the fermentation medium is 2-5 mg / L, the pH is 7-8, and the time is 36-48 hours.

10. The microbial treatment method according to claim 1, characterized in that: In step (2), during the microbial denitrification process, the water temperature in the wastewater treatment device is controlled to be 25-30°C.

Images