A green and efficient microbial treatment method for removing nitrate nitrogen in high-salinity wastewater

Abstract

The present application belongs to the technical field of nitrate nitrogen wastewater treatment, and particularly relates to a green and efficient microbial treatment method for removing nitrate nitrogen in high-salinity wastewater. The method inoculates a methanotroph with nitrate assimilation and reduction function into wastewater containing nitrate nitrogen to remove the nitrate nitrogen in the wastewater, so that the final effluent nitrate nitrogen reaches the standard, and no intermediate products such as nitrous oxide and nitrogen are produced, and the removed nitrogen from the wastewater can also be recovered by collecting the biomass precipitate. Compared with the traditional biological denitrification process, the method can remove nitrate nitrogen and organic matter in a single reactor, reducing the requirements for reactor size and subsequent energy costs; at the same time, the microbial treatment method of the present application is simple to operate, the reaction is mild, the removal efficiency of nitrate nitrogen is high, and it can be applied to wastewater with a wide range of salinity for denitrification treatment, and has wide application value in sewage treatment projects.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of nitrate nitrogen wastewater treatment. More specifically, it relates to a green and efficient microbial treatment method for removing nitrate nitrogen from high-salinity wastewater. BACKGROUND

[0002] Nitrogen (N) is an important chemical element, and the cycle of nitrogen in the ecosystem is crucial to ecological balance. With frequent industrial production activities and increasing agricultural nitrogen fertilizer application, a large amount of active nitrogen exists in wastewater generated by human activities, and direct discharge will cause great nitrogen load to the natural ecological environment, thereby causing a series of ecological problems caused by nitrogen pollution. At present, the main approach for treating nitrate nitrogen in wastewater is biological denitrification, which first oxidizes ammonia nitrogen to nitrate nitrogen (nitrification) and then reduces nitrate nitrogen to nitrogen gas (denitrification) to effectively remove nitrate nitrogen in water. However, during the nitrification-denitrification process, N2O may be released as a byproduct, which as a potent greenhouse gas exacerbates global warming. On the other hand, it is challenging to remove nitrate nitrogen from high-salinity wastewater. High-salinity environments can inhibit the metabolism and growth of microorganisms, and the growth rate of many microorganisms will be significantly reduced. Salt can inhibit enzyme activity and cellular metabolic processes, resulting in a slower rate of cell proliferation and affecting the efficiency of nitrogen removal by microorganisms.

[0003] Microorganisms with the function of aerobic heterotrophic reduction of nitrate nitrogen have been studied, and the assimilative reduction of nitrate nitrogen by microorganisms is one of the important processes of nitrogen transformation in the environment. After nitrate nitrogen is reduced to ammonium by heterotrophic bacteria, biomass nitrogen is synthesized and stored in the microorganism, and no intermediate products such as N2O are produced, which is an environmentally friendly nitrogen transformation process. Compared with the traditional biological denitrification process by autotrophic nitrifying bacteria and heterotrophic denitrifying bacteria, nitrate assimilating bacteria can remove nitrate nitrogen and organic matter in a single reactor, reducing the requirement for reactor size and subsequent energy costs. At the same time, the pathway for removing nitrate nitrogen through assimilation is shorter, which means that microorganisms can remove nitrogen in the environment faster than the nitrification-denitrification process. For example, Chinese Patent Application CN103923867A discloses a mixed microbial consortium microbial preparation composed of Pseudomonas stutzeri, Pseudomonas chlororaphis, Pseudomonas pseudoalcaligenes, and Pseudomonas oleovorans, which is used to treat wastewater containing nitrate nitrogen. It needs to be cultured for 4 days to achieve complete denitrification, and the denitrification efficiency still needs to be further improved.

[0004] Therefore, there is an urgent need to develop a green and environmentally friendly method for removing nitrate nitrogen from high-salinity wastewater to address the challenge of high-salinity and high-activity nitrogen content in wastewater generated by current human activities. SUMMARY

[0005] The present application aims to overcome the defects and deficiencies in the prior art that it takes 4 days to achieve complete denitrification after culturing and the denitrification efficiency still needs to be further improved, and provides the application of Methylophaga murata in treating high-nitrate nitrogen wastewater.

[0006] Another object of the present application is to provide a green and efficient microbial treatment method for removing nitrate nitrogen in high-salinity wastewater.

[0007] The above objects of the present application are achieved by the following technical solutions.

[0008] The present application protects the application of Methylophaga murata in treating high-nitrate nitrogen wastewater, and the Methylophaga murata was deposited at the Guangdong Microbial Culture Collection Center on February 28, 2012, with a deposit number of GDMCC NO: 1.508.

[0009] Further, the Methylophaga murata is changed to Methylophaga muralis.

[0010] The present application protects a microbial treatment method for removing nitrate nitrogen in high-salinity wastewater, which comprises the following steps: adjusting the pH value of the nitrate nitrogen-containing wastewater to 6-9, inoculating Methylophaga murata bacterial liquid therein, thoroughly mixing, and performing microbial denitrification under aerobic conditions.

[0011] The Methylophaga murata bacterial liquid is in the form of adhering to a microbial carrier or is directly put into the nitrate nitrogen-containing wastewater.

[0012] The Methylophaga murata was deposited at the Guangdong Microbial Culture Collection Center on February 28, 2012, with a deposit number of GDMCC NO: 1.508.

[0013] Further, the OD 600 value of the Methylophaga murata bacterial liquid is greater than or equal to 0.8.

[0014] Preferably, the inoculation amount of the Methylophaga murata bacterial liquid is 5%-40% based on the volume percentage of the nitrate nitrogen-containing wastewater.

[0015] Further, the Methylophaga murata bacterial liquid is in the form of adhering to a microbial carrier or is directly put into the nitrate nitrogen-containing wastewater.

[0016] Further, when the Methylophaga murata bacterial solution is directly put into the nitrate-containing wastewater, the inoculation amount of the Methylophaga murata bacterial solution is 5% to 15%, and more preferably 8 to 12%.

[0017] Further, when the Methylophaga murata bacterial solution is put into the nitrate-containing wastewater in the form of being attached to the microbial carrier, the inoculation amount of the Methylophaga murata bacterial solution is 30% to 40%.

[0018] When the scale of the wastewater to be treated is small, and the volume of the nitrate-containing wastewater is ≤1L, the Methylophaga murata bacterial solution can also be directly put into the nitrate-containing wastewater to quickly perform the microbial denitrification process.

[0019] When the scale of the wastewater to be treated is large, and the volume of the nitrate-containing wastewater is >1L, the Methylophaga murata bacterial solution is put into the nitrate-containing wastewater in the form of being attached to the microbial carrier (i.e., the immobilized microbial technology), which can more quickly perform the microbial denitrification process. This is because the immobilized microbial technology can make the microorganisms highly dense and maintain the biological activity, and under suitable conditions, the microorganisms can quickly and massively proliferate. This technology applied to wastewater treatment is beneficial to increasing the concentration of microorganisms (especially special functional microorganisms) in the biological reactor, resisting the influence of the adverse environment, separating the solid and liquid after the reaction, and shortening the time required for treatment.

[0020] Further, the preparation method of the Methylophaga murata bacterial solution comprises the following steps:

[0021] S1. inoculating the Methylophaga murata on a solid culture medium and culturing until single colonies grow;

[0022] S2. picking the single colonies obtained in step S1 to perform seed culture to obtain a seed solution;

[0023] S3. inoculating the seed solution obtained in step S2 into a liquid culture medium to perform expansion culture to obtain the Methylophaga murata bacterial solution.

[0024] Further, the OD 600 value is the absorbance of the bacterial solution measured at a wavelength of 600 nm.

[0025] When the Methylophaga murata bacterial solution is put into the nitrate-containing wastewater in the form of being attached to the microbial carrier, the preparation method of the Methylophaga murata bacterial solution comprises the following steps:

[0026] S1. inoculating Methylophaga murata on solid culture medium and culturing until single colonies grow;

[0027] S2. picking single colonies obtained in step S1 to perform seed culture to obtain seed liquid;

[0028] S3. inoculating the seed liquid obtained in step S2 into liquid culture medium to perform expansion culture; after the OD 600 value of the bacterial liquid is ≥0.8, putting sterilized microbial carriers into the bacterial liquid to continue culturing, so that the Methylophaga murata bacterial liquid is fully attached to the microbial carriers to obtain the Methylophaga murata bacterial liquid.

[0029] Further, the time for the continued culturing is 10-14 h.

[0030] Further, the sterilization preferably is high-pressure steam sterilization at 121℃ for 20 minutes.

[0031] Specifically, in step S3, the seed liquid obtained in step S2 is inoculated into liquid culture medium to perform expansion culture; a spectrophotometer is used to detect the absorbance of the bacterial liquid at 600 nm to monitor the growth of the Methylophaga murata bacterial liquid, and after the OD 600 value of the bacterial liquid is ≥0.8, putting sponge filler and sandstone particles, which are sterilized at 121℃ for 20 minutes and naturally cooled, into the bacterial liquid at a mass ratio of 1:2 to continue culturing the bacterial liquid at a temperature of 30℃ and a rotation speed of 160 rpm for 12 h to obtain the Methylophaga murata bacterial liquid.

[0032] Preferably, the microbial carriers include one or more of sponge filler, sandstone particles, and activated carbon.

[0033] Further, the Methylophaga murata bacterial liquid is fixed on the microbial carriers by physical adsorption.

[0034] Further, the mixing ratio of the Methylophaga murata bacterial liquid and the microbial carriers is 1:(15-30) L / g, preferably 1:18 L / g.

[0035] Further, the wastewater containing nitrate nitrogen includes nutrients.

[0036] Still further, the nutrients or the liquid culture medium include carbon source, nitrogen source, inorganic salt, trace element, and vitamin.

[0037] Further, the carbon source is mainly derived from methanol. The carbon source provides energy and carbon skeleton required for cell growth.

[0038] Further, the nitrogen source is mainly derived from one or more of nitrate, ammonium salt, amino acid. The nitrogen source can provide nitrogen element required for cell synthesis of protein and nucleic acid.

[0039] Further, the inorganic salt is mainly derived from one or more of phosphate, sulfate, magnesium salt, potassium salt, sodium salt, and specifically includes one or more of potassium nitrate, potassium dihydrogen phosphate, magnesium sulfate, sodium chloride, sodium bicarbonate, sodium carbonate. The inorganic salt can provide macroelement required for cell growth.

[0040] Further, the trace element includes one or more of iron, manganese, copper, zinc, cobalt, boron, calcium. Specifically, iron can be derived from ferrous sulfate heptahydrate, manganese can be provided by manganese chloride tetrahydrate, boron can be provided by boric acid, calcium can be derived from calcium chloride, cobalt can be provided by cobalt chloride hexahydrate, copper can be provided by copper sulfate pentahydrate, and zinc can be provided by zinc sulfate heptahydrate. Although the demand for trace elements is small, they are essential for cell growth.

[0041] Further, the vitamin is preferably vitamin B12. Vitamins are involved in a variety of biochemical reactions in cells and have a promoting effect on cell growth.

[0042] Specifically, as a preferred embodiment, the nutrient substance (or liquid medium) (1L) contains potassium nitrate (1g), potassium dihydrogen phosphate (1g), magnesium sulfate (0.22g), sodium chloride (30g), methanol (10mL), trace element solution (1mL), vitamin B12 (20μg), and additionally 2mol / L sodium bicarbonate solution and 1mol / L sodium carbonate solution are prepared, and 50mL and 10mL of each are added to each liter of medium.

[0043] Further, the trace element solution (1L) contains manganese chloride tetrahydrate (4.0g), ferrous sulfate heptahydrate (2.0g), boric acid (1.0g), calcium chloride (1.0g), cobalt chloride hexahydrate (1.6g), copper sulfate pentahydrate (1.5g), and zinc sulfate heptahydrate (3.0g).

[0044] Preferably, the temperature for microbial denitrification is 20-32℃, more preferably 28-32℃. The temperature for microbial denitrification is consistent with the growth temperature, because it is necessary to maintain good biological activity of the microorganism during denitrification. The Methylophaga murata bacterial solution can grow and maintain good activity at the above-mentioned temperature, and can perform microbial denitrification.

[0045] Further, the temperature for culturing the Methylophaga murata bacterial solution is 20-32℃.

[0046] Preferably, the temperature of the liquid culture of the Methylophaga murata is 28-32℃.

[0047] Further, the rotation speed of the liquid culture of the Methylophaga murata is 120-200 rpm, preferably 150-180 rpm.

[0048] Further, the culture medium is used after sterilization, and the sterilization condition is preferably 121℃ for 20 min, and used after cooling to room temperature.

[0049] Further, the vitamin B12 solution is injected into the culture medium after passing through a 0.22 μm filter after sterilization and cooling of the culture medium.

[0050] Further, the solid culture medium is obtained by adding 1.5%-3% (mass percentage of the liquid culture medium) agar powder to the liquid culture medium, preferably 2%.

[0051] Further, the nitrate nitrogen in the wastewater containing nitrate nitrogen is 10-200 mg / L. When the concentration of nitrate nitrogen in the water body does not exceed 200 mg / L, the microbial treatment method of the present application can convert all the nitrate nitrogen contained in the culture medium into biomass nitrogen and store it in the microorganism within 14 hours, achieving the purpose of denitrification of the water environment.

[0052] Compared with the prior art, the present application has the following beneficial effects:

[0053] The microbial treatment method of the present application inoculates a strain of salt-tolerant bacteria with nitrate assimilation and reduction function into wastewater containing nitrate nitrogen to remove nitrate nitrogen in the wastewater. When the nitrate nitrogen in the effluent reaches the standard, all the nitrate nitrogen is converted into biomass nitrogen and stored in the microorganism, without producing intermediate products such as nitrous oxide and nitrogen gas. At the same time, the removed nitrogen from the wastewater can be recovered by collecting the biomass precipitate. Compared with the traditional biological denitrification process, this method can remove nitrate nitrogen and organic matter in a single reactor, reducing the requirement for reactor size and subsequent energy cost. At the same time, the microbial treatment method of the present application is simple to operate, mild in reaction, high in removal efficiency of nitrate nitrogen, and can be applied to wastewater with a wide range of salinity for denitrification treatment, and has wide application value in sewage treatment engineering. BRIEF DESCRIPTION OF DRAWINGS

[0054] Figure 1 is a data statistical graph of the denitrification effect of Methylophaga murata in the laboratory on a small scale.

[0055] Figure 2 is a schematic diagram of the reactor.

[0056] Figure 3 Figure 2 is a data statistical chart of the growth of Methylophaga murata under different initial nitrate nitrogen concentration conditions.

[0057] Figure 4 Figure 3 is a data statistical chart of the denitrification effect of Methylophaga murata under different initial nitrate nitrogen concentration conditions.

[0058] Figure 5 Figure 4 is a data statistical chart of the conversion of nitrate nitrogen by Methylophaga murata under different initial nitrate nitrogen concentration conditions.

[0059] Figure 6 Figure 5 is a statistical table chart of the nitrogen conversion related functional metabolic genes carried by Methylophaga murata.

[0060] Figure 7 Figure 6 is a statistical table chart of the salt tolerance strategy related functional metabolic genes carried by Methylophaga murata.

[0061] Figure 8 Figure 7 is a data statistical chart of the denitrification effect of Pseudomonas chengduensis under the same salinity. DETAILED DESCRIPTION

[0062] The present application will be further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present application in any form. Unless otherwise specified, the reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the technical field.

[0063] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0064] Methylophaga murata was deposited in the Guangdong Microbial Culture Collection Center on February 28, 2012, and the deposit number is GDMCC NO: 1.508.

[0065] Pseudomonas chengduensis was deposited in the Guangdong Microbial Culture Collection Center on July 20, 2020, and the deposit number is GDMCC NO: 1.2017.

[0066] The above two strains are directly purchased from the Guangdong Microbial Culture Collection Center, and the preservation information can be directly obtained by inquiring the Guangdong Microbial Culture Collection Center.

[0067] Example 1 Preparation of Methylophaga murata pure bacterial liquid

[0068] The method for preparing the pure Methylophaga murata liquid culture includes the following steps:

[0069] S1. Inoculate Methylophaga murata on solid culture medium and cultivate until single colonies grow;

[0070] S2. Pick the single colonies obtained in step S1 to carry out seed culture at 30°C for 48h to obtain seed liquid;

[0071] S3. Inoculate the seed liquid obtained in step S2 into liquid culture medium and carry out expansion culture at 30°C to obtain Methylophaga murata liquid culture. Use a spectrophotometer to detect the absorbance of the liquid culture at 600nm to monitor the growth of the microorganism. When the OD value of the liquid culture is greater than 0.8, pour the sponge filler and sandstone particles, which have been sterilized by high-pressure steam at 121°C for 20min and naturally cooled, into the liquid culture at a mass ratio of 1:2. Continue to cultivate the liquid culture at a temperature of 30°C and a rotation speed of 160rpm for 12h to fix the microorganism and the carrier by physical adsorption. The mixing ratio of Methylophaga murata liquid culture and the microorganism carrier is 1:18L / g. 600

[0072] The suitable culture medium (1L, liquid culture medium here) for cultivating Methylophaga murata contains potassium nitrate (1g), potassium dihydrogen phosphate (1g), magnesium sulfate (0.22g), sodium chloride (30g), methanol (10mL), trace element solution (1mL), vitamin B12 (20μg), and additionally prepared 2mol / L sodium bicarbonate solution and 1mol / L sodium carbonate solution, 50mL and 10mL of which are added into each liter of the culture medium. The trace element solution (1L) contains manganese chloride tetrahydrate (4.0g), ferrous sulfate heptahydrate (2.0g), boric acid (1.0g), calcium chloride (1.0g), cobalt chloride hexahydrate (1.6g), copper sulfate pentahydrate (1.5g), and zinc sulfate heptahydrate (3.0g). The culture medium is sterilized at 121°C for 20min and used after cooling to room temperature. The vitamin B12 solution is injected into the culture medium after the culture medium is sterilized and cooled by passing through a 0.22μm filter membrane.

[0073] The solid culture medium is prepared by adding 2% (mass percentage of the liquid culture medium) agar powder to the liquid culture medium.

[0074] Example 2: Experiment on the denitrification effect of Methylophaga murata in a small scale in the laboratory

[0075] 1. Experimental method ​

[0076] A green and efficient microbial treatment method for removing nitrate nitrogen in high salinity wastewater, specifically comprising the following steps:

[0077] According to the step S3 of Example 1, 10 mL of bacterial solution was inoculated into 100 mL of suitable liquid medium, and potassium nitrate was added to the liquid medium to make the initial nitrate nitrogen content 200 mg / L. Under aerobic conditions, without adding sponge filler and gravel particles, the liquid medium was cultured at 30°C and 150 rpm, and the effluent was collected every two hours. The effluent was filtered through a 0.22 μm filter membrane, and the extracellular nitrate nitrogen was determined. The concentration of nitrate nitrogen was determined by phenol disulfonic acid spectrophotometry.

[0078] 2. Experimental results

[0079] The conversion of Methylophaga murata to nitrate nitrogen under the condition of initial nitrate nitrogen concentration of 200 mg / L is shown in Figure 1 The results show that under laboratory small-scale culture conditions, the speed of microbial denitrification is faster and the efficiency is higher, and the effect of complete removal of nitrate nitrogen is achieved in 10 h. Even without adding fillers to enrich and fix the microorganisms, good nitrate nitrogen removal effect can be achieved.

[0080] Example 3: Denitrification effect of Methylophaga murata in the reactor (large scale)

[0081] 1. Experimental method

[0082] A green and efficient microbial treatment method for removing nitrate nitrogen in high salinity wastewater, specifically comprising the following steps:

[0083] S1. Use the existing reactor in the laboratory, and the device schematic diagram is shown in Figure 2 The top is provided with a water inlet and a water outlet, and the Methylophaga murata bacterial solution is put into the reactor in the form of a microbial carrier prepared in Example 1, and the addition amount is 37% of the reactor volume. The total volume of the reactor is 5 L, of which the liquid medium (the same as in Example 1) is 60% of the reactor volume. The upper part is left as a gas phase space. The stirrer circulates the water flow clockwise at 60 r / min to make the microorganisms fully contact with the culture medium. The reactor temperature is maintained at 30°C by using an electric heating jacket during the entire operation period. The reactor is operated in cycles, including sampling period, reaction period, precipitation period and drainage period. During the water inlet period, the peristaltic pump is used to enter from the corresponding water inlet, and the high salinity wastewater to be treated is added. During the drainage period, the supernatant is discharged, and sodium bicarbonate and potassium dihydrogen phosphate are added as buffer to control the pH value, and sodium bicarbonate and potassium dihydrogen phosphate can also be used as inorganic carbon source and phosphorus source substrate by microorganisms.

[0084] S2. Set up three independent reactors, adjust the nitrate nitrogen concentration in the high salinity wastewater to be 10 mg / L, 100 mg / L and 200 mg / L respectively by adding potassium nitrate, and adjust the initial pH of the wastewater to 8 (use hydrochloric acid and sodium hydroxide to adjust). Then put the microbial carrier and bacteria liquid mixture prepared in Example 1 into the reactor, and the addition amount is 37% of the total liquid volume in the reactor. Start the reactor under aerobic conditions, and collect water samples every two hours during the operation of the reactor. After filtration through a 0.22 μm filter membrane, the extracellular nitrate nitrogen is determined. At 0 hours, 8 hours and 16 hours of cultivation, 10 mL of effluent water sample is taken for determination of extracellular inorganic nitrogen and intracellular organic nitrogen. The concentration of nitrate nitrogen is determined by phenol disulfonic acid spectrophotometry; the concentration of nitrite nitrogen is determined by diazotization coupling spectrophotometry; the concentration of ammonium nitrogen is determined by sodium reagent spectrophotometry; and the intracellular organic nitrogen is determined by alkaline potassium persulfate ultraviolet spectrophotometry after centrifugation of the water sample and washing the precipitate three times with sterile ultrapure water.

[0085] 2. Experimental results

[0086] Start the reactor, adjust the initial nitrate nitrogen concentration in the initial influent, and obtain the growth of Methylophaga murata under different conditions as shown in Figure 3 With the increase of initial nitrate nitrogen concentration, the growth rate of microorganisms is faster, and the final cumulative biomass in the reactor is higher. When the content of nitrate nitrogen is not more than 200 mg / L, the cultivation time needs to last at least 18 h; when the content of nitrate nitrogen is greater than 200 mg / L, the cultivation time is appropriately prolonged according to the actual detection situation.

[0087] The denitrification effect of Methylophaga murata under different initial nitrate nitrogen concentrations is shown in Figure 4 When the concentration of nitrate nitrogen in the water body is not more than 200 mg / L, the nitrate nitrogen contained in the culture medium will be completely converted into biomass nitrogen stored in the microorganism within 14 hours, achieving the purpose of water body environmental denitrification.

[0088] The conversion of nitrate nitrogen by Methylophaga murata under different initial nitrate nitrogen concentrations is shown in Figure 5 The assimilation and reduction of nitrate nitrogen by microorganisms go through three stages of nitrate nitrogen→nitrite nitrogen→ammonium nitrogen. Since nitrite nitrogen may have a toxic effect when accumulated in the body, a small amount of nitrite nitrogen can be detected extracellularly when the initial nitrate nitrogen concentration is high, but when the effluent nitrate nitrogen reaches the standard, all the nitrate nitrogen is converted into biomass nitrogen stored in the microorganism, without producing intermediate products such as nitrous oxide, nitrogen gas, etc. At the same time, the removed nitrogen from the wastewater can be recovered by collecting the biomass precipitate.

[0089] Example 4 Determination of nitrogen conversion and salt tolerance strategy related functional metabolic genes carried by Methylophaga murata

[0090] 1. Experimental method

[0091] Methylophaga murata genome information (GenBank No. GCF_001720165.1) was downloaded from the GenBank DNA sequence database of the National Center for Biotechnology Information, and ORFs were predicted by using Prodigal on the Methylophaga murata genome, and the predicted ORFs were subjected to kofam database alignment by DIAMOND blastx (v2.0.15) for functional gene annotation.

[0092] 2. Experimental results

[0093] The inventors' team found that the Methylophaga murata strain contains only complete nitrate assimilation reduction functional genes (nasA, nasD, nasE) in multiple nitrogen conversion pathways, and has multiple nitrate transport genes (nrtA, nrtB, nrtC, nrtP), which can rapidly transport nitrate nitrogen in wastewater into cells to undergo nitrate assimilation reduction process, and will not occur other possible intermediate product nitrate nitrogen conversion pathways, and also has the functions of assimilating and reducing nitrite nitrogen in wastewater (nasD, nasE) and assimilating ammonium nitrogen (amt, glnA, gltB, gltD, gdhA) Figure 6 ) in wastewater. On the other hand, this strain contains multiple salt tolerance strategy genes, including intracellular Na + transport to extracellular strategy (nqrB, nqrE, nqrF), absorption of extracellular K+ to maintain osmotic pressure strategy (kdpC, kup, phaA, phaC, phaG), synthesis of soluble small molecule compounds to maintain osmotic pressure strategy (ectA, ectB, ectC, otsA, gdh, proA, proC, proB) Figure 7 ) The diverse salt adaptation strategies enable the Methylophaga murata strain to be applied in a wider range of wastewater (0.3-20 wt% in terms of sodium chloride concentration) for denitrification treatment in the present application.

[0094] Comparative Example 1 A microbial treatment method for removing nitrate nitrogen in high-salinity wastewater

[0095] The difference from Example 3 is that Methylophaga murata is replaced by Pseudomonas chengduensis with nitrate nitrogen assimilation reduction function to carry out the enrichment process as in Example 1 and the experimental process as in Example 2, the initial influent nitrate nitrogen concentration is ensured to be 200 mg / L, and the rest of the culture conditions are the same as in Example 2.

[0096] The results, as shown in Figure 8 The denitrification rate and the denitrification effect of Pseudomonas chengduensis after 16 hours are lower than those of Methylophaga murata, a plateau is reached at 14 hours, and the decrease of the nitrate nitrogen concentration in the wastewater is very small with the continuous increase of the denitrification time.

[0097] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods and are included in the protection scope of the present application.

Claims

1. A microbial treatment method for removing nitrate nitrogen from high salinity wastewater, characterized by, Comprising the following steps: The pH value of the wastewater containing nitrate nitrogen is adjusted to 6-9, and the bacterial solution is inoculated into the wastewater Methylophaga murata The bacterial solution is mixed thoroughly, and the denitrification is carried out under aerobic conditions. Wherein, the Methylophaga murata The bacterial solution is in the form of adhering to the microbial carrier or is directly put into the wastewater containing nitrate nitrogen. The Methylophaga murata It was preserved in Guangdong Provincial Microbial Culture Collection Center on February 28, 2012, and the preservation number is GDMCC NO: 1.

508. The Methylophaga murata The method for preparing the bacterial solution comprises the following steps: S1. Incubate Methylophaga murata Inoculate solid medium and incubate until single colonies grow; S2. Pick up the single colony obtained in step S1 for seed culture to obtain a seed solution; S3. The seed liquid obtained in step S2 is inoculated into liquid culture medium for expansion culture to obtain a bacterial liquid. Methylophaga murata Bacterial liquid.

2. The microorganism treatment method according to claim 1, characterized by, The Methylophaga murata OD of the bacterial solution 600 value ≥ 0.

8.

3. The method of claim 2, wherein the microorganism is a bacterium. The Methylophaga murata OD value of the bacterial solution after being put into the wastewater containing nitrate nitrogen 600 ≤ 0.

1.

4. The method of claim 2, wherein the microorganism is a bacterium. in an amount of 0.1 to 10% by volume based on the volume of the wastewater containing nitrate nitrogen Methylophaga murata The inoculation amount of the bacterial solution is 5% to 40%.

5. The microorganism treatment method according to any one of claims 1 to 4, characterized by, The Methylophaga murata The method for preparing the bacterial solution comprises the following steps: S1. Incubate Methylophaga murata Inoculate solid medium and incubate until single colonies grow; S2. Pick up the single colony obtained in step S1 for seed culture to obtain a seed solution; S3. Inoculate the seed culture obtained in step S2 into the liquid culture medium for expansion culture; when the OD of the bacterial culture... 600 Once the value is ≥0.8, a sterilized microbial carrier is added to the bacterial culture, and cultivation continues. Methylophaga murata The bacterial solution fully adheres to the microbial carrier, thus obtaining... Methylophaga murata Bacterial solution.

6. The method of claim 1, wherein the microorganism is a bacterium. The microbial carrier comprises one or more of sponge filler, sandstone particles and activated carbon.

7. The method of claim 1, wherein the microorganism is a bacterium. The wastewater containing nitrate nitrogen comprises nutrients.

8. The method of claim 1, wherein the microorganism is a bacterium. The temperature of the microbial denitrification is 20-32℃.

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