CN112048500A

CN112048500A - Paracoccus denitrificans/Shewanella/graphene/calcium alginate denitrification gel microsphere as well as preparation method and application thereof

Info

Publication number: CN112048500A
Application number: CN202010816280.9A
Authority: CN
Inventors: 陈银广; 蒋萌; 董磊
Original assignee: Tongji University
Current assignee: Tongji University
Priority date: 2020-08-14
Filing date: 2020-08-14
Publication date: 2020-12-08

Abstract

The invention discloses paracoccus denitrificans/Shewanella/graphene/calcium alginate denitrification gel microspheres and a preparation method and application thereof, and belongs to the technical field of environmental protection. According to the invention, denitrifying microorganisms P.dentificans, S.oneidensis MR-1 and graphene are embedded by calcium alginate to form P.dentificans/S.oneidensis MR-1/graphene/calcium alginate denitrifying gel microspheres, the prepared microspheres have strong toxic and harmful environmental impact resistance, and can realize the recycling of strains and materials, when the microspheres are applied to an anaerobic denitrifying system polluted by nitrate or nitrate composite, the time required by the nitrate to reach 90% removal rate can be greatly shortened, and the accumulation of intermediate products of nitrite and nitrous oxide is reduced.

Description

Paracoccus denitrificans/Shewanella/graphene/calcium alginate denitrification gel microsphere as well as preparation method and application thereof

Technical Field

The invention relates to a paracoccus denitrificans/Shewanella/graphene/calcium alginate denitrification gel microsphere and a preparation method and application thereof, belonging to the technical field of environmental protection.

Background

Over the past few decades, with the increasing human activities and the large scale use of nitrogen-containing fertilizers, it has inevitably resulted in the introduction of large amounts of bioavailable nitrogen, such as nitrates, into the environment. The microbial anaerobic denitrification is an important component of the global nitrogen cycle process, and the process of reducing nitrate in soil or water into nitrogen provides an effective way for the removal and transformation of nitrate in the environment. However, the actual bio-anaerobic denitrification process is slow and there is also some accumulation of intermediate products of the nitrate reduction process, such as nitrite and nitrous oxide. Not only does the presence of nitrite jeopardize the survival of aquatic organisms and human health, its accumulation can also affect the proper functioning of functional microorganisms in sewage treatment systems. Nitrous oxide is a potential greenhouse gas with 300 times the greenhouse potential of carbon dioxide, and is a very important ozone depletion source, estimated as the current trend of increasing nitrous oxide emissions (around 7%), it will become the largest ozone depleting substance in the 21 st century. In addition, nitrate pollution is usually accompanied by pollution of petroleum, volatile phenols and heavy metals, and according to literature reports, organic pollutants represented by phenols and heavy metals represented by uranium can inhibit microbial denitrification to different degrees and can cause accumulation of a large amount of intermediate products, namely nitrite and nitrous oxide. Therefore, how to remarkably promote the anaerobic denitrification efficiency of microorganisms in nitrate-polluted water bodies, particularly nitrate-combined-polluted water bodies, and reduce the accumulation of intermediate products is a problem which needs to be solved urgently at present.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a denitrifying paracoccus denitrificans/Shewanella/graphene/calcium alginate gel microsphere and a preparation method and application thereof, the denitrifying microorganisms P.densihisans, S.oneidensis MR-1 and graphene are embedded by calcium alginate to form the P.densihisans/S.oneidensis MR-1/graphene/calcium alginate gel microsphere, the prepared microsphere has strong toxic and harmful environment impact resistance, the bacterial strain and material can be recycled, when the microsphere is applied to an anaerobic denitrification system polluted by nitrate or polluted by nitrate, the time required by 90% of nitrate removal rate can be greatly shortened, and the accumulation of intermediate products of nitrite and nitrous oxide is reduced.

In order to achieve the technical purpose, the technical scheme of the invention is as follows:

a preparation method of paracoccus denitrificans/Shewanella/graphene/calcium alginate denitrification gel microspheres comprises the following steps:

will OD₆₀₀Adding 3 bacterial liquid of paracoccus denitrificans P.Denitrificans and S.oneidensis MR-1 bacterial liquid of Shewanella S.oneidensis into the graphene dispersion liquid, uniformly mixing to obtain mixed liquid, and obtaining the OD of P.Denitrificans in the mixed liquid₆₀₀OD of 3, P.dentificans and S.oneidenesis MR-1₆₀₀The ratio of (1: 5) to (1: 5) is 5:1, and the concentration of graphene is 0.1-1 mg/mL; then uniformly mixing the mixed solution with an isometric sodium alginate solution, and dropwise adding the mixed solution to a proper amount of CaCl₂In the solution, the concentration of the sodium alginate solution is 20-40 g/L, CaCl₂The mass concentration of the solution is 0.5-4%, and the target microspheres are obtained after stirring reaction for 2 hours at room temperature.

Preferably, the OD of p.dentificans in the mixed solution₆₀₀OD of 3, P.dentificans and S.oneidenesis MR-1₆₀₀The ratio of (1: 2) is 0.5mg/mL of graphene, 30g/L of sodium alginate solution and CaCl₂The mass concentration of the solution was 2%.

The paracoccus denitrificans/Shewanella/graphene/calcium alginate denitrification gel microsphere prepared by the preparation method is adopted.

The microspheres are applied to the anaerobic denitrification process.

Preferably, the steps are: headAdding organic pollutants or heavy metal pollutants into a denitrification culture medium, then adding microspheres, and then adding CH₃COONa, adjusting pH of the system with an acid-base regulator, and blowing N₂Removing oxygen, sealing, sterilizing, and then carrying out anaerobic denitrification culture under the conditions that the carbon-nitrogen ratio is 1-8, the temperature is 10-35 ℃, and the pH is 6.0-9.0.

Further preferably, the denitrification medium comprises the following components: 21.36mM KNO₃,10.66 mM NH₄Cl,0.41mM MgSO₄·7H₂O,17.93mM KH₂PO₄,32.76mM Na₂HPO₄3.00mM lactic acid Lactate, 0.2g/L yeast extract and 1mL/L trace elements; wherein each 1mL of trace elements contains 7.3mg of Na₂-EDTA、2.43mg FeCl₃·6H₂O、0.02mg MnCl₂·4H₂O、0.242mg Na₂MoO₄·2H₂O、0.135mg CuCl₂·2H₂O and 0.34mg ZnCl₂。

Further preferably, the organic contaminant is phenol, and the concentration of phenol in the denitrification medium is 0.5 mM.

Further preferably, the organic contaminant is uranium, and the concentration of uranium in the denitrification medium is 0.08 mM.

Further preferably, the addition amount of the microspheres is: 1.5mL of microspheres were added per 100mL of denitrification medium.

Further preferably, the anaerobic denitrification culture is performed at a carbon-nitrogen ratio of 5, a temperature of 30 ℃ and a pH of 7.0.

From the above description, it can be seen that the present invention has the following advantages:

the inventors found in the study that when s.oneidensis MR-1 is added alone to an anaerobic denitrification medium containing p.dentrificans for anaerobic denitrification, s.oneidensis MR-1 can only enhance the denitrification efficiency of p.dentrificans by promoting the generation of nanowires of microorganisms having conductive properties, whereas when s.oneidensis MR-1 and nanographene sheets are added together to an anaerobic denitrification medium containing p.dentrificans for anaerobic denitrification, on the one hand, s.oneidensis MR-1 can enhance the denitrification efficiency of p.dentrificans by promoting the generation of nanowires, and nanographene sheets can enhance the denitrification efficiency by inter-species electron transfer with the denitrifying microorganisms p.dentrificans, on the other hand, the co-presence of nanographene sheets and p.dentrificans can promote the generation of pigments of conductive pigments in the s.onensis MR function, and further enhance the transfer of the conductive pigments in the cells of s.extracellular Denitrica, further promoting the reduction efficiency of the P.Denitrificans on nitrate and reducing the accumulation of intermediate products of nitrite and nitrous oxide.

According to the invention, denitrifying microorganisms P.dentifrices, S.oneidensis MR-1 and graphene are embedded by calcium alginate to form P.dentifrices/S.oneidensis MR-1/graphene/calcium alginate, the microspheres have strong toxic and harmful environmental impact resistance, and can realize the recycling of strains and materials, in addition, in a nitrate pollution (nitrate-phenol composite pollution/nitrate-uranium composite pollution) anaerobic denitrification system, the S.oneidensis MR-1, the nano graphene sheet and the denitrifying microorganism P.dentifrices in the microspheres are mutually cooperated, so that the electron transfer rate of the P.dentifrices can be greatly improved, the anaerobic denitrification efficiency of the P.dentifrices is remarkably accelerated, the time required by the nitrate removal rate reaching 90% is greatly shortened, and the accumulation of intermediate products and nitrous oxide is reduced.

According to the invention, the anaerobic denitrification efficiency can be further improved by optimizing the microsphere preparation conditions and the denitrification conditions.

Drawings

FIG. 1 is an image of the denitrifying gel microspheres PSG, PS, PG and P prepared by the invention;

FIG. 2 is the average time required for the nitrate removal rate to reach 90% in 5-time recycling of the denitrifying gel microspheres PSG, PS, PG and P in the absence of other contaminants in example 1;

FIG. 3 is the average maximum cumulative concentration of nitrite in the course of 5 times of recycling of the denitrifying gel microspheres PSG, PS, PG, P in the absence of other contaminants of example 1;

FIG. 4 is the average highest cumulative concentration of nitrous oxide during 5 times of recycling of the denitrifying gel microspheres PSG, PS, PG, P in the absence of other contaminants of example 1;

FIG. 5 is the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the denitrifying gel microsphere PSG, PS, GS and S after 1 time of utilization in the absence of other pollutants in example 1;

FIG. 6 is the average time required for the nitrate removal rate to reach 90% in 5-time repeated utilization of the denitrifying gel microspheres PSG, PS, PG and P in the presence of phenol in example 1;

FIG. 7 is the average time required for the nitrate removal rate to reach 90% in the 5-time recycling process of the denitrification gel microspheres PSG, PS, PG and P in the presence of uranium in example 1;

Detailed Description

The features of the invention will be further elucidated by the following examples, without limiting the claims of the invention in any way.

Example 1

Separately culturing denitrifying microorganisms paracoccus denitrificans P, Denitrificans (American model culture collection and storage, strain No. ATCC 19367, the same below) and Shewanella S.oneidensis MR-1 (American model culture collection and storage, strain No. ATCC 700550, the same below) in aerobic condition to stationary phase of microorganism growth, centrifuging, collecting and resuspending to obtain OD₆₀₀3 of P.dentitificans bacterial liquid and S.oneidedensis MR-1 bacterial liquid; ultrasonically dispersing graphene into distilled water to obtain a graphene dispersion liquid;

the container selected for culturing the denitrification system is an aseptic anaerobic bottle, and a denitrification culture medium contains the following components: 21.36mM KNO₃,10.66mM NH₄Cl,0.41mM MgSO₄·7H₂O,17.93mM KH₂PO₄,32.76 mM Na₂HPO₄3.00mM lactic acid Lactate, 0.2g/L yeast extract and 1mL/L trace elements; wherein each 1mL of trace elements contains 7.3mg of Na₂-EDTA、2.43mg FeCl₃·6H₂O、0.02mg MnCl₂·4H₂O、0.242mg Na₂MoO₄·2H₂O、0.135mg CuCl₂·2H₂O and 0.34mg ZnCl₂。

Preparation of denitrifying gel microspheres:

preparation of denitrifying gel microspheres PSG: will OD₆₀₀Adding 3 of P.dentitificans bacterial liquid and S.oneidedensis MR-1 bacterial liquid into the graphene dispersion liquid, uniformly mixing to obtain a mixed liquid, and obtaining the OD of P.dentitificans in the mixed liquid₆₀₀OD of 3, P.dentificans and S.oneidenesis MR-1₆₀₀The ratio of (1: 2) and the concentration of graphene is 0.5 mg/mL; then uniformly mixing the mixed solution with an isometric sodium alginate solution, and dropwise adding the mixed solution to a proper amount of CaCl₂In the solution, the concentration of the sodium alginate solution is 30g/L, CaCl₂The mass concentration of the solution is 2% (w/v), and the target P.Denitrificans/S.oneidensis MR-1/graphene/calcium alginate denitrifying gel microsphere PSG is obtained after stirring and reacting for 2h at room temperature.

Preparation of denitrifying gel microsphere PS: the same method as that for preparing the microspheres PSG was used to prepare p.densitificans/s.oneidedensis MR-1/calcium alginate denitrifying gel microspheres PS, with the only difference that the graphene dispersion was replaced with the same volume of distilled water.

Preparation of the denitrifying gel microsphere PG: the same method as that for preparing the microsphere PSG is adopted to prepare the P, denitirificans/graphene/calcium alginate denitrifying gel microsphere PG, and the difference is that OD is used₆₀₀The S.oneidensis MR-1 strain at 3 was replaced by the same volume of distilled water.

Preparation of denitrifying gel microspheres GS: preparing graphene/S.oneidensis MR-1/calcium alginate denitrifying gel microspheres GS by the same method as preparing the microspheres PSG, and only distinguishing the difference that OD is used₆₀₀The 3 P.dentificans broth was replaced with the same volume of distilled water.

Preparation of denitrifying gel microspheres P: p. Denitrificans/calcium alginate denitrifying gel microspheres P were prepared by the same method as for the microspheres PSG, except that OD was adjusted₆₀₀S.onei of 3The dentists MR-1 bacterial liquid and the graphene dispersion liquid are replaced by distilled water with the same volume.

Preparation of denitrifying gel microspheres S: s. oneidensis MR-1/calcium alginate denitrifying gel microspheres S are prepared by the same method as for preparing the microspheres PSG, except that OD is added₆₀₀The same volume of distilled water was replaced with 3 p.

Preparing blank sodium alginate gel microspheres: s. oneidensis MR-1/calcium alginate denitrifying gel microspheres S are prepared by the same method as for preparing the microspheres PSG, except that OD is added₆₀₀The same volume of distilled water was replaced with 3 of P.dentificans bacterial liquid, S.oneidensis MR-1 bacterial liquid, and graphene dispersion liquid.

The prepared denitrification gel microspheres PSG, PS, PG, GS, P and S are applied to an anaerobic denitrification process, and the specific experimental steps are as follows:

experimental group 1: 1.5mL of microspheres were added to 100mL of the above denitrification medium, followed by addition of CH₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 30 deg.C and pH of 7.0 at carbon-nitrogen ratio of 5. After the anaerobic denitrification culture is finished, the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the PSG, PS, GS and S microspheres is tested, and is shown in FIG. 5. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90%, the maximum cumulative concentration of nitrite and the highest cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the results are shown in figures 2-4 after 5 times of averaging.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 51.8%, 42.2% and 21.8%, the average maximum cumulative concentration of nitrite is reduced by 89.6%, 80.6% and 72.9%, and the average maximum cumulative concentration of nitrous oxide is reduced by 84.1%, 70.4% and 66.1%.

The results show that compared with the microspheres S, PS and GS, the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the microsphere PSG is improved by 4.10, 2.92 and 2.35. This indicates that P.dentifrices or graphene alone cannot promote the production of a large amount of cytochrome in S.oneidensis MR-1 in the anaerobic denitrification system, but that P.dentifrices, graphene and S.oneidensis MR-1 can promote the production of a large amount of cytochrome in S.oneidenedisis MR-1 when they coexist.

Experimental group 2: phenol was added to 100mL of the above denitrification medium to a concentration of 0.5mM, 1.5mL of microspheres was added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 30 deg.C and pH of 7.0 at carbon-nitrogen ratio of 5. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90 percent, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the results are shown in figure 6 after 5 times of averaging.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 48.1%, 24.8% and 17.1%, the average maximum cumulative concentration of nitrite is reduced by 81.8%, 77.8% and 42.8%, and the average maximum cumulative concentration of nitrous oxide is reduced by 85.0%, 83.3% and 40.0%.

Experimental group 3: first, uranium was added to 100mL of the above-mentioned denitrification medium to a concentration of 0.08mM, then 1.5mL of microspheres were added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 30 deg.C and pH of 7.0 at carbon-nitrogen ratio of 5. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90% in each anaerobic denitrification process is tested, and the results are shown in figure 7 after 5 times of averaging.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 35.2%, 27.4% and 16.8%, the average maximum cumulative concentration of nitrite is reduced by 21.1%, 18.6% and 10.4%, and the average maximum cumulative concentration of nitrous oxide is reduced by 33.1%, 25.4% and 20.6%.

Example 2

Preparation of denitrifying gel microspheres:

preparation of denitrifying gel microspheres PSG: will OD₆₀₀Adding 3 of P.dentitificans bacterial liquid and S.oneidedensis MR-1 bacterial liquid into the graphene dispersion liquid, uniformly mixing to obtain a mixed liquid, and obtaining the OD of P.dentitificans in the mixed liquid₆₀₀OD of 3, P.dentificans and S.oneidenesis MR-1₆₀₀The ratio of (1) to (5) is 0.1 mg/mL; then uniformly mixing the mixed solution with an isometric sodium alginate solution, and dropwise adding the mixed solution to a proper amount of CaCl₂In the solution, the concentration of the sodium alginate solution is 20g/L, CaCl₂The mass concentration of the solution is 0.5% (w/v), and the target P.dentificas/S.oneidensis MR-1/graphene/calcium alginate denitrification gel microsphere PSG is obtained after stirring and reacting for 2h at room temperature.

Preparation of denitrifying gel microsphere PS: p. dentrificans/s. oneidensis MR-1/calcium alginate denitrifying gel microspheres SP were prepared in the same way as microspheres PSG, except that the graphene dispersion was replaced with the same volume of distilled water.

Preparation of denitrifying gel microspheres P: miningPreparation of P. Denitrificans/calcium alginate denitrifying gel microspheres P in the same way as for the microspheres PSG, except that OD is adjusted₆₀₀The s.oneidensis MR-1 bacterial solution and graphene dispersion of 3 were replaced by the same volume of distilled water.

experimental group 1: to 100mL of the same denitrification medium as in example 1 was added 1.5m microspheres, followed by CH₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 10 deg.C and pH of 6.0 under carbon-nitrogen ratio of 2. And after the anaerobic denitrification culture is finished, testing the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the PSG, PS, GS and S microspheres. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90 percent, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the average value is taken for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 33.6%, 21.9% and 14.5%, the average maximum cumulative concentration of nitrite is reduced by 46.4%, 38.5% and 47.6%, and the average maximum cumulative concentration of nitrous oxide is reduced by 36.4%, 29.9% and 21.4%.

The results show that compared with the microspheres S, PS and GS, the characteristic absorption peak intensities of the cytochrome contained in the extracellular polymer in the microsphere PSG are improved by 1.01, 0.81 and 0.77.

Experimental group 2: phenol was added to 100mL of the same denitrification medium as in example 1 to a concentration of 0.5mM, 1.5mL of microspheres were added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 10 deg.C and pH of 6.0 under carbon-nitrogen ratio of 2. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90 percent, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the average value is taken for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 20.1%, 14.1% and 11.1%, the average maximum cumulative concentration of nitrite is reduced by 50.2%, 32.6% and 18.9%, and the average maximum cumulative concentration of nitrous oxide is reduced by 54.6%, 48.5% and 24.1%.

Experimental group 3: first, uranium was added to 100mL of the same denitrification medium as in example 1 to a concentration of 0.08mM, then 1.5mL of microspheres were added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 10 deg.C and pH of 6.0 under carbon-nitrogen ratio of 2. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90% in each anaerobic denitrification process is tested, and the average value is obtained for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 20.6%, 18.7% and 8.0%, the average maximum cumulative concentration of nitrite is reduced by 22.3%, 25.9% and 8.4%, and the average maximum cumulative concentration of nitrous oxide is reduced by 20.5%, 21.4% and 18.0%.

Example 3

Preparation of denitrifying gel microspheres:

preparation of denitrifying gel microspheres PSG: will OD₆₀₀Adding 3 of P.dentitificans bacterial liquid and S.oneidedensis MR-1 bacterial liquid into the graphene dispersion liquid, uniformly mixing to obtain a mixed liquid, and obtaining the OD of P.dentitificans in the mixed liquid₆₀₀OD of 3, P.dentificans and S.oneidenesis MR-1₆₀₀The ratio of (1: 5) and the concentration of graphene is 1 mg/mL; then uniformly mixing the mixed solution with an isometric sodium alginate solution, and dropwise adding the mixed solution to a proper amount of CaCl₂In the solution, the concentration of the sodium alginate solution is 40g/L, CaCl₂The mass concentration of the solution is 4% (w/v), and the target P.Denitrificans/S.oneidensis MR-1/graphene/calcium alginate denitrifying gel microsphere PSG is obtained after stirring and reacting for 2h at room temperature.

Preparation of denitrifying gel microspheres P: p. Denitrificans/calcium alginate denitrifying gel microspheres P were prepared by the same method as for the microspheres PSG, except that OD was adjusted₆₀₀S. oneidenesis MR-1 of 3And replacing the bacteria liquid and the graphene dispersion liquid with distilled water with the same volume.

experimental group 1: to 100mL of the same denitrification medium as in example 1 was added 1.5m microspheres, followed by CH₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 35 deg.C and pH of 9.0 at a carbon-nitrogen ratio of 8. And after the anaerobic denitrification culture is finished, testing the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the PSG, PS, GS and S microspheres. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90 percent, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the average value is taken for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 40.8%, 33.7% and 18.8%, the average maximum cumulative concentration of nitrite is reduced by 58.6%, 64.1% and 53.2%, and the average maximum cumulative concentration of nitrous oxide is reduced by 63.8%, 51.2% and 43.3%.

The results show that compared with the microspheres S, PS and GS, the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the microsphere PSG is improved by 1.89, 1.64 and 1.25.

Experimental group 2: phenol was added to 100mL of the same denitrification medium as in example 1 to a concentration of 0.5mM, 1.5mL of microspheres were added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 35 deg.C and pH of 9.0 at a carbon-nitrogen ratio of 8. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90 percent, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the average value is taken for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 31.3%, 19.3% and 14.3%, the average maximum cumulative concentration of nitrite is reduced by 67.9%, 44.5% and 28.3%, and the average maximum cumulative concentration of nitrous oxide is reduced by 67.7%, 60.4% and 21.6%.

Experimental group 3: first, uranium was added to 100mL of the same denitrification medium as in example 1 to a concentration of 0.08mM, then 1.5mL of microspheres were added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 35 deg.C and pH of 9.0 at a carbon-nitrogen ratio of 8. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90% in each anaerobic denitrification process is tested, and the average value is obtained for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 18.1%, 10.9% and 10.8%, the average maximum cumulative concentration of nitrite is reduced by 12.5%, 11.6% and 27.8%, and the average maximum cumulative concentration of nitrous oxide is reduced by 15.4%, 8.5% and 11.9%.

Example 4

Preparation of denitrifying gel microspheres:

preparation of denitrifying gel microspheres PSG: will OD₆₀₀Adding 3 of P.dentitificans bacterial liquid and S.oneidedensis MR-1 bacterial liquid into the graphene dispersion liquid, uniformly mixing to obtain a mixed liquid, and obtaining the OD of P.dentitificans in the mixed liquid₆₀₀OD of 3, P.dentificans and S.oneidenesis MR-1₆₀₀The ratio of (1: 2) and the concentration of graphene is 1 mg/mL; then uniformly mixing the mixed solution with an isometric sodium alginate solution, and dropwise adding the mixed solution to a proper amount of CaCl₂In the solution, the concentration of the sodium alginate solution is 20g/L, CaCl₂The mass concentration of the solution is 2% (w/v), and the target P.Denitrificans/S.oneidensis MR-1/graphene/calcium alginate denitrifying gel microsphere PSG is obtained after stirring and reacting for 2h at room temperature.

Preparation of denitrifying gel microspheres P: p. Denitrificans/calcium alginate denitrifying gel microspheres P were prepared by the same method as for the microspheres PSG, except that OD was adjusted₆₀₀The s.oneidensis MR-1 bacterial solution and graphene dispersion of 3 were replaced by the same volume of distilled water.

Preparation of denitrifying gel microspheres S: using and preparing microsphere PSG phaseThe same method for preparing S.oneidensis MR-1/calcium alginate denitrifying gel microsphere S only differs from the method that OD is added₆₀₀The same volume of distilled water was replaced with 3 p.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 37.1%, 26.4% and 19.3%, the average maximum cumulative concentration of nitrite is respectively reduced by 37.5%, 33.6% and 34.8%, and the average maximum cumulative concentration of nitrous oxide is respectively reduced by 41.3%, 38.8% and 24.9%.

The results show that compared with the microspheres S, PS and GS, the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the microsphere PSG is improved by 1.98, 1.79 and 1.52.

Experimental group 2: first to 100mL of the same denitrification medium as in example 1 was added phenol to a concentration of 0.5mM, 1.5mL of microspheres was added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 10 deg.C and pH of 6.0 under carbon-nitrogen ratio of 2. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90 percent, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the average value is taken for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 24.0%, 20.7% and 14.7%, the average maximum cumulative concentration of nitrite is reduced by 52.7%, 37.4% and 24.0%, and the average maximum cumulative concentration of nitrous oxide is reduced by 46.8%, 55.3% and 26.4%.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 20.1%, 17.6% and 15.1%, the average maximum cumulative concentration of nitrite is reduced by 15.6%, 14.3% and 11.5%, and the average maximum cumulative concentration of nitrous oxide is reduced by 24.1%, 17.6% and 14.5%.

Example 5

Preparation of denitrifying gel microspheres:

denitrificationPreparation of gel microsphere PSG: will OD₆₀₀Adding 3 of P.dentitificans bacterial liquid and S.oneidedensis MR-1 bacterial liquid into the graphene dispersion liquid, uniformly mixing to obtain a mixed liquid, and obtaining the OD of P.dentitificans in the mixed liquid₆₀₀OD of 3, P.dentificans and S.oneidenesis MR-1₆₀₀The ratio of (1) to (5) is 5:1, and the concentration of the graphene is 0.5 mg/mL; then uniformly mixing the mixed solution with an isometric sodium alginate solution, and dropwise adding the mixed solution to a proper amount of CaCl₂In the solution, the concentration of the sodium alginate solution is 40g/L, CaCl₂The mass concentration of the solution is 1% (w/v), and the target P.Denitrificans/S.oneidensis MR-1/graphene/calcium alginate denitrifying gel microsphere PSG is obtained after stirring and reacting for 2h at room temperature.

Preparation of denitrifying gel microspheres S: s. oneidensis MR-1/calcium alginate denitrifying gel microspheres S are prepared by the same method as for preparing the microspheres PSG, except that OD is added₆₀₀3 bacteria of P.dentificans andthe graphene dispersion was replaced with the same volume of distilled water.

experimental group 1: to 100mL of the same denitrification medium as in example 1 was added 1.5m microspheres, followed by CH₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 35 deg.C and pH of 7.0 at a carbon-nitrogen ratio of 8. And after the anaerobic denitrification culture is finished, testing the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the PSG, PS, GS and S microspheres. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90 percent, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the average value is taken for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 28.6%, 24.3% and 23.9%, the average maximum cumulative concentration of nitrite is respectively reduced by 41%, 32.2% and 36.1%, and the average maximum cumulative concentration of nitrous oxide is respectively reduced by 62%, 36.8% and 44.4%.

The results show that compared with the microspheres S, PS and GS, the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the microsphere PSG is improved by 1.42, 1.22 and 1.1.

Experimental group 2: phenol was added to 100mL of the same denitrification medium as in example 1 to a concentration of 0.5mM, 1.5mL of microspheres were added, and CH was added₃COONa with NaOH orHCl pH adjustment of the System, bubbling N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 35 deg.C and pH of 7.0 at a carbon-nitrogen ratio of 8. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90 percent, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the average value is taken for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 30.0%, 22.5% and 24.4%, the average maximum cumulative concentration of nitrite is reduced by 66.1%, 45.4% and 28.6%, and the average maximum cumulative concentration of nitrous oxide is reduced by 71.3%, 64.9% and 28.8%.

Experimental group 3: first, uranium was added to 100mL of the same denitrification medium as in example 1 to a concentration of 0.08mM, then 1.5mL of microspheres were added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 35 deg.C and pH of 7.0 at a carbon-nitrogen ratio of 8. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90% in each anaerobic denitrification process is tested, and the average value is obtained for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 26.8%, 29.2% and 20.9%, the average maximum cumulative concentration of nitrite is reduced by 21.0%, 11.5% and 14.4%, and the average maximum cumulative concentration of nitrous oxide is reduced by 21.7%, 17.3% and 11.9%.

Example 6

Preparation of denitrifying gel microspheres:

preparation of denitrifying gel microspheres PSG: will OD₆₀₀Adding the P.dentitificans bacterial liquid and the S.oneidensis MR-1 bacterial liquid which are both 3 into the graphene dispersion liquid, and uniformly mixing to obtain the graphene dispersion liquidMixed solution, OD of P.Denitrificans in the obtained mixed solution₆₀₀OD of 3, P.dentificans and S.oneidenesis MR-1₆₀₀The ratio of (1: 5) and the concentration of graphene is 0.1 mg/mL; then uniformly mixing the mixed solution with an isometric sodium alginate solution, and dropwise adding the mixed solution to a proper amount of CaCl₂In the solution, the concentration of the sodium alginate solution is 30g/L, CaCl₂The mass concentration of the solution is 3% (w/v), and the target P.Denitrificans/S.oneidensis MR-1/graphene/calcium alginate denitrifying gel microsphere PSG is obtained after stirring and reacting for 2h at room temperature.

Preparing blank sodium alginate gel microspheres: using and preparingBall PSG preparation of S.oneidensis MR-1/calcium alginate denitrifying gel microspheres S in the same way as the ball PSG except that OD is adjusted₆₀₀The same volume of distilled water was replaced with 3 of P.dentificans bacterial liquid, S.oneidensis MR-1 bacterial liquid, and graphene dispersion liquid.

experimental group 1: to 100mL of the same denitrification medium as in example 1 was added 1.5m microspheres, followed by CH₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 30 deg.C and pH of 8.0 at carbon-nitrogen ratio of 5. And after the anaerobic denitrification culture is finished, testing the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the PSG, PS, GS and S microspheres. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90 percent, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the average value is taken for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 41.3%, 37.5% and 16.9%, the average maximum cumulative concentration of nitrite is respectively reduced by 66.5%, 51.2% and 47.1%, and the average maximum cumulative concentration of nitrous oxide is respectively reduced by 53.3%, 46.9% and 45.3%.

The results show that compared with the microspheres S, PS and GS, the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the microsphere PSG is improved by 2.35, 2.11 and 1.48.

Experimental group 2: phenol was added to 100mL of the same denitrification medium as in example 1 to a concentration of 0.5mM, 1.5mL of microspheres were added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and adjusting carbon-nitrogen ratioAnaerobic denitrification culture was carried out at 30 ℃ and pH 8.0 at 5. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90 percent, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the average value is taken for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 32.4%, 19.2% and 14.0%, the average maximum cumulative concentration of nitrite is reduced by 69.3%, 56.4% and 30.8%, and the average maximum cumulative concentration of nitrous oxide is reduced by 72.3%, 60.4% and 24.0%.

Experimental group 3: first, uranium was added to 100mL of the same denitrification medium as in example 1 to a concentration of 0.08mM, then 1.5mL of microspheres were added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 30 deg.C and pH of 8.0 at carbon-nitrogen ratio of 5. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90% in each anaerobic denitrification process is tested, and the average value is obtained for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 20.7%, 13.5% and 14.3%, the average maximum cumulative concentration of nitrite is reduced by 16.7%, 10.4% and 9.8%, and the average maximum cumulative concentration of nitrous oxide is reduced by 14.4%, 11.6% and 10.6%.

Example 7

Preparation of denitrifying gel microspheres:

preparation of denitrifying gel microspheres PSG: will OD₆₀₀Adding 3 of P.dentitificans bacterial liquid and S.oneidedensis MR-1 bacterial liquid into the graphene dispersion liquid, uniformly mixing to obtain a mixed liquid, and obtaining the OD of P.dentitificans in the mixed liquid₆₀₀OD of 3, P.dentificans and S.oneidenesis MR-1₆₀₀In a ratio of 1:5The concentration of the graphene is 0.3 mg/mL; then uniformly mixing the mixed solution with an isometric sodium alginate solution, and dropwise adding the mixed solution to a proper amount of CaCl₂In the solution, the concentration of the sodium alginate solution is 35g/L, CaCl₂The mass concentration of the solution is 1.5% (w/v), and the target P.dentificans/S.oneidensis MR-1/graphene/calcium alginate denitrification gel microsphere PSG is obtained after stirring and reacting for 2h at room temperature.

Preparing blank sodium alginate gel microspheres: s. oneidensis MR-1/calcium alginate denitrifying gel microspheres S are prepared by the same method as for preparing the microspheres PSG, except that OD is added₆₀₀3 pThe same volume of distilled water is replaced by the can bacterial liquid, the S.oneidensis MR-1 bacterial liquid and the graphene dispersion liquid.

experimental group 1: to 100mL of the same denitrification medium as in example 1 was added 1.5m microspheres, followed by CH₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 25 deg.C and pH of 7.0 under the condition of carbon-nitrogen ratio of 4. And after the anaerobic denitrification culture is finished, testing the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the PSG, PS, GS and S microspheres. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90 percent, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the average value is taken for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 38.0%, 18.9% and 16.8%, the average maximum cumulative concentration of nitrite is respectively reduced by 63.3%, 42.4% and 65.2%, and the average maximum cumulative concentration of nitrous oxide is respectively reduced by 46.9%, 30.1% and 31.6%.

The results show that compared with the microspheres S, PS and GS, the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the microsphere PSG is improved by 1.82, 1.47 and 1.21.

Experimental group 2: phenol was added to 100mL of the same denitrification medium as in example 1 to a concentration of 0.5mM, 1.5mL of microspheres were added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 25 deg.C and pH of 7.0 under the condition of carbon-nitrogen ratio of 4. The PSG, PS, PG and P microspheres are recycled for 5 times, and each time of anaerobic denitrification is testedThe time required for the nitrate removal rate to reach 90%, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in the process were averaged 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 26.3%, 18.1% and 10.8%, the average maximum cumulative concentration of nitrite is reduced by 44.1%, 38.8% and 24.6%, and the average maximum cumulative concentration of nitrous oxide is reduced by 41.3%, 40.1% and 18.9%.

Experimental group 3: first, uranium was added to 100mL of the same denitrification medium as in example 1 to a concentration of 0.08mM, then 1.5mL of microspheres were added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 25 deg.C and pH of 7.0 under the condition of carbon-nitrogen ratio of 4. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90% in each anaerobic denitrification process is tested, and the average value is obtained for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 21.0%, 17.5% and 9.8%, the average maximum cumulative concentration of nitrite is reduced by 14.3%, 13.4% and 7.7%, and the average maximum cumulative concentration of nitrous oxide is reduced by 15.4%, 10% and 11.4%.

Example 8

Preparation of denitrifying gel microspheres:

preparation of denitrifying gel microspheres PSG: will OD₆₀₀Adding 3 of P.dentitificans bacterial liquid and S.oneidedensis MR-1 bacterial liquid into the graphene dispersion liquid, uniformly mixing to obtain a mixed liquid, and obtaining the OD of P.dentitificans in the mixed liquid₆₀₀OD of 3, P.dentificans and S.oneidenesis MR-1₆₀₀The ratio of (1) to (5) is 0.8 mg/mL; then uniformly mixing the mixed solution with an isometric sodium alginate solution, and dropwise adding the mixed solution to a proper amount of CaCl₂In solution, whereinThe concentration of the sodium alginate solution is 25g/L, CaCl₂The mass concentration of the solution is 2.5% (w/v), and the target P.dentificans/S.oneidensis MR-1/graphene/calcium alginate denitrification gel microsphere PSG is obtained after stirring and reacting for 2h at room temperature.

experimental group 1: to 100mL of the same denitrification medium as in example 1 was added 1.5m microspheres, followed by CH₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 15 deg.C and pH of 8.0 at carbon-nitrogen ratio of 6. And after the anaerobic denitrification culture is finished, testing the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the PSG, PS, GS and S microspheres. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90 percent, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the average value is taken for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 34.4%, 28.1% and 14%, the average maximum cumulative concentration of nitrite is respectively reduced by 58.8%, 45.0% and 43.3%, and the average maximum cumulative concentration of nitrous oxide is respectively reduced by 60.6%, 58.4% and 46.2%.

The results show that compared with the microspheres S, PS and GS, the characteristic absorption peak intensity of the cytochrome contained in the extracellular polymer in the microsphere PSG is improved by 1.57, 1.08 and 0.86.

Experimental group 2: phenol was added to 100mL of the same denitrification medium as in example 1 to a concentration of 0.5mM, 1.5mL of microspheres were added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 15 deg.C and pH of 8.0 at carbon-nitrogen ratio of 6. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90 percent, the maximum cumulative concentration of nitrite and the maximum cumulative concentration of nitrous oxide in each anaerobic denitrification process are tested, and the average value is taken for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 37.0%, 20.8% and 10.2%, the average maximum cumulative concentration of nitrite is reduced by 68.1%, 34.2% and 21.1%, and the average maximum cumulative concentration of nitrous oxide is reduced by 6.8%, 63.2% and 19.4%.

Experimental group 3: first, uranium was added to 100mL of the same denitrification medium as in example 1 to a concentration of 0.08mM, then 1.5mL of microspheres were added, and CH was added₃COONa, adjusting the pH of the system with NaOH or HCl, blowing N₂Removing oxygen for 5min, sealing with butyl rubber diaphragm and aluminum cover, sterilizing at 121 deg.C for 15min, and performing anaerobic denitrification culture at 15 deg.C and pH of 8.0 at carbon-nitrogen ratio of 6. The PSG, PS, PG and P microspheres are recycled for 5 times, the time required for the nitrate removal rate to reach 90% in each anaerobic denitrification process is tested, and the average value is obtained for 5 times.

The results show that compared with the microspheres P, PG and PS, the average time required for the nitrate removal rate to reach 90% in the anaerobic denitrification system in which the microspheres PSG are positioned is respectively shortened by 26.5%, 18.6% and 13.6%, the average maximum cumulative concentration of nitrite is reduced by 24.1%, 14.6% and 11.4%, and the average maximum cumulative concentration of nitrous oxide is reduced by 19.60%, 12.2% and 11.0%.

It should be understood that the detailed description of the invention is merely illustrative of the invention and is not intended to limit the invention to the specific embodiments described. It will be appreciated by those skilled in the art that the present invention may be modified or substituted equally as well to achieve the same technical result; as long as the use requirements are met, the method is within the protection scope of the invention.

Claims

1. A preparation method of paracoccus denitrificans/Shewanella/graphene/calcium alginate denitrification gel microspheres is characterized by comprising the following steps:

will OD₆₀₀3 bacteria of Paracoccus denitrificans P.Denitricifica and Shewanella S.oneidensis MR-1 were addedUniformly mixing the graphene dispersion liquid to obtain a mixed liquid, wherein the OD of the P.Denitrificans in the mixed liquid is obtained₆₀₀OD of 3, P.dentificans and S.oneidenesis MR-1₆₀₀The ratio of (1: 5) to (1: 5) is 5:1, and the concentration of graphene is 0.1-1 mg/mL; then uniformly mixing the mixed solution with an isometric sodium alginate solution, and dropwise adding the mixed solution to a proper amount of CaCl₂In the solution, the concentration of the sodium alginate solution is 20-40 g/L, CaCl₂The mass concentration of the solution is 0.5-4%, and the target microspheres are obtained after stirring reaction for 2 hours at room temperature.

2. The method according to claim 1, wherein the mixed solution contains OD of P₆₀₀OD of 3, P.dentificans and S.oneidenesis MR-1₆₀₀The ratio of (1: 2) is 0.5mg/mL of graphene, 30g/L of sodium alginate solution and CaCl₂The mass concentration of the solution was 2%.

3. Paracoccus denitrificans/shewanella/graphene/calcium alginate denitrification gel microspheres prepared by the preparation method of claim 1 or 2.

4. Use of the microspheres of claim 3 in an anaerobic denitrification process.

5. The use of claim 4, characterized by the steps of: firstly, adding organic pollutants or heavy metal pollutants into a denitrification culture medium, then adding microspheres, and then adding CH₃COONa, adjusting pH of the system with an acid-base regulator, and blowing N₂Removing oxygen, sealing, sterilizing, and then carrying out anaerobic denitrification culture under the conditions that the carbon-nitrogen ratio is 1-8, the temperature is 10-35 ℃, and the pH is 6.0-9.0.

6. The use according to claim 5, wherein the denitrification medium comprises the following components: 21.36mM KNO₃,10.66mM NH₄Cl,0.41mM MgSO₄·7H₂O,17.93mM KH₂PO₄,32.76mM Na₂HPO₄3.00mM lactic acid Lactate, 0.2g/L yeast extract and 1mL/L trace elements; wherein each 1mL of trace elements contains 7.3mg of Na₂-EDTA、2.43mg FeCl₃·6H₂O、0.02mg MnCl₂·4H₂O、0.242mg Na₂MoO₄·2H₂O、0.135mg CuCl₂·2H₂O and 0.34mg ZnCl₂。

7. The use according to claim 5, wherein the organic contaminant is phenol and the concentration of phenol in the denitrification medium is 0.5 mM.

8. Use according to claim 5, wherein the organic contaminant is uranium, the concentration of uranium in the denitrification medium being 0.08 mM.

9. The use of claim 5, wherein the microspheres are added in an amount of: 1.5mL of microspheres were added per 100mL of denitrification medium.

10. The use according to claim 5, wherein the anaerobic denitrification culture is carried out at a carbon to nitrogen ratio of 5, a temperature of 30 ℃ and a pH of 7.0.