CN109650561B - A kind of denitrification functional filler and its preparation and application - Google Patents

Abstract

The invention discloses a denitrification functional filler and its preparation and application. It consists of the following components in parts by mass, reduced iron powder 20-30%, activated carbon 8-10%, sulfur 30-40%, metal catalyst 2-6%, binder 15-20%, pore-forming agent 3- 5%, pH adjuster 3‑5%, and 15‑20% water based on the sum of the mass of the components. It belongs to the denitrification functional filler that reduces the amount of carbon source added. The denitrification functional filler is prepared by the following preparation method: the components are prepared and mixed according to the described mass ratio, and 15-20% of the water of the sum of the mass of the components is slowly added to form a viscous mixed material, The mixed material is placed in a mold, the mold is placed in a vacuum drying oven for drying, and after demolding, drying is performed in a vacuum drying oven to form pores to prepare a denitrification functional filler.

Description

A kind of denitrification functional filler and its preparation and application

technical field

The invention relates to nitrogen-containing domestic sewage and industrial wastewater treatment technology, in particular to a denitrification functional filler and its preparation and application.

Background technique

With the development of the economy, due to the improvement of human living standards and the excessive use of agricultural fertilizers, a large amount of nitrogen-containing domestic sewage and industrial wastewater are discharged into the water body. Excessive nitrogen content will cause eutrophication of the water body, and can be converted into Nitrite nitrogen, which is the "Three Consistent" substances, is a serious threat to human health. When the human body ingests excessive nitrate nitrogen, it will cause abdominal pain, diarrhea, vomiting, essential hypertension, respiratory infection, abnormal immune system, and increase the risk of birth defects in the central nervous system of the baby. In addition, nitrate nitrogen will be converted into nitrite nitrogen in the human body, which is 11 times more toxic than nitrate nitrogen, and will induce a series of diseases, affect human health, and cause adverse effects on society. Therefore, the research and development of economical and efficient wastewater denitrification treatment technology has become the focus and hotspot in the field of water pollution control engineering. At present, researchers at home and abroad can generally divide nitrate nitrogen removal technology into physical method, chemical method and biological method according to different treatment methods. Physical methods include ion exchange resin method, reverse osmosis membrane method and electrodialysis membrane method. The chemical method mainly reduces nitrate nitrogen through catalysts. Commonly used catalytic reducing agents include active metals (such as Fe, Al, etc.) and non-metals (such as hydrogen, etc.). Biological method refers to the use of autotrophic or heterotrophic microorganisms for denitrification to finally convert nitrate nitrogen into nitrogen gas, so as to achieve complete removal of nitrate. Because biological denitrification technology has the advantages of high efficiency and low energy consumption. According to the different carbon sources required by microorganisms, groundwater biological denitrification technology can be divided into heterotrophic denitrification technology and autotrophic denitrification technology. Among many denitrification technologies, biological denitrification technology has the characteristics of economy, high efficiency and no secondary pollution. In recent years, the research on the denitrification function of anaerobic reactors has become a hot spot.

In traditional autotrophic denitrification reactors, people only use iron autotrophic denitrification technology or sulfur autotrophic denitrification technology to remove nitrogen. Among them, simply through the iron autotrophic denitrification technology, the iron carbon filler will generate a large amount of OH ^- when the galvanic reaction occurs in the water, so that the pH of the water will continue to rise, which is not suitable for the survival of microorganisms; Ferric oxide will be formed on the surface of the filler, which hinders the progress of the micro-electrolysis reaction and the growth of microorganisms. Similarly, a large amount of H ⁺ will be generated during the simple sulfur autotrophic denitrification reaction, which will make the pH in the reactor continue to increase. decline, ultimately unsuitable for microbial growth, and high concentrations of SO ₄ ^2- can cause accumulation of nitrous nitrogen.

SUMMARY OF THE INVENTION

The main function of the filler is to accommodate the attached microorganisms, it is the carrier for the growth of microorganisms, and provides a stable environment for microorganisms to inhabit and reproduce. quantity. At the same time, the packing has a mandatory turbulent effect on the water flow, so that the water flow can be redistributed and its flow direction can be changed, so that the water flow can be distributed more uniformly under the cross section of the reactor. The filler has a certain retention effect on the suspended solids in the water. Due to the presence of fillers in the reactor, the concentration of suspended solids in the effluent is greatly reduced. Therefore, the role of fillers in the sewage treatment process is very important. Therefore, the development of suitable biological fillers is the premise for the promotion and application of biological denitrification technology in the field of water treatment in the future.

In order to solve the above technical problems, the present invention provides a denitrification functional filler and its preparation and application, specifically a denitrification functional filler with reduced carbon source dosage. Through the integrated filler, the iron autotrophic denitrification technology and the sulfur autotrophic denitrification technology were creatively combined, which solved the problem of too high or too low pH in the reactor, and no accumulation of nitrate nitrogen and nitrite nitrogen was found. And has a good removal effect. In this filler, iron powder and activated carbon are used to generate iron-carbon micro-electrolysis in water, and ferrous iron and reducing hydrogen are produced to reduce nitrate nitrogen to nitrogen. At the same time, iron acts as an oxygen scavenger to capture and consume dissolved oxygen in groundwater, creating In the anaerobic environment necessary for the denitrification process, denitrifying bacteria use hydrogen and sulfur as electron donors, which can reduce the addition of organic carbon sources, thereby achieving autotrophic denitrification. Nitrate nitrogen is removed by biochemical methods. At the same time, the filler has fast film hanging speed, good denitrification performance under the best operating process parameters, and is widely available and inexpensive.

In order to achieve the purpose of the present invention, the present invention provides a denitrification functional filler. The denitrification functional filler is composed of the following components in parts by mass: 20-30% of reduced iron powder, 8-10% of activated carbon, and 30-30% of sulfur. 40%, metal catalyst 2-5%, binder 15-20%, pore-forming agent 3-5%, pH adjuster 3-5%.

In the denitrification functional filler provided by the present invention, the metal catalyst is selected from one or more of copper powder, magnesium powder, tin powder, manganese powder and titanium powder.

In the denitrification functional filler provided by the present invention, the binder is one or more of calcium sulfate, sodium alginate, gum arabic and polyvinyl alcohol.

In the denitrification functional filler provided by the present invention, the pore-forming agent is selected from one or both of ammonium bicarbonate and ammonium oxalate.

In the denitrification functional filler provided by the present invention, the pH adjuster is selected from one or more of sodium bicarbonate, sodium dihydrogen phosphate, sodium hydroxide and calcium carbonate.

In the denitrification functional filler provided by the present invention, the particle size of the reduced iron powder is 150-200 mesh; the particle size of the activated carbon is 150-200 mesh; the particle size of the sulfur particle is 0.5-1 mm; the metal catalyst The particle size is 150-200 mesh.

In the denitrification functional filler provided by the present invention, the denitrification functional filler is a sphere with a diameter of 9-12 mm.

On the other hand, the present invention provides the preparation method of the above-mentioned denitrification functional filler, comprising the following steps:

Mix the components according to the stated mass ratio, slowly add 15-20% water of the sum of the mass of the components to form a viscous mixed material, place the mixed material in the mold, put the mold It is placed in a vacuum drying oven to dry, and after demoulding, it is dried in a vacuum drying oven to make pores to make denitrification functional fillers. Optionally, the preparation process of the denitrification functional filler consists of the above steps.

In the preparation method of the denitrification functional filler provided by the present invention, the drying conditions in the vacuum drying box for placing the mold are drying at 45-60° C. for 6-8 hours;

In the preparation method of the denitrification functional filler provided by the present invention, the drying conditions for drying the pores in a vacuum drying oven are drying at 100-120°C.

Another object of the present invention is to provide an application of a denitrification functional filler in an anaerobic reactor that reduces the amount of carbon source added.

In the application of the denitrification functional packing provided by the present invention in the anaerobic reactor, the dissolved oxygen concentration of the sewage in the anaerobic reactor is 1.0-2.0 mg/L, and the ratio of the COD concentration to the nitrate nitrogen concentration in the sewage is 3≥C/N≥1.5; if C/N is greater than 3, the heterotrophic denitrifying bacteria in the reactor will dominate, and the heterotrophic bacteria and autotrophic bacteria are in a competitive relationship. reduce, the filler loses its effect;

The volume of the denitrification functional filler is 50-80% of the volume of the anaerobic reactor;

In the anaerobic reactor, heterotrophic denitrifying bacteria, iron autotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria are screened as dominant bacteria.

Beneficial effects of the present invention:

(1) The filler has a large specific surface area, above 245.6 m ² /g, which provides sufficient space for the attachment of microorganisms, so that as many microorganisms as possible exist in the reactor. At the same time, the filler will also change the flow direction of the water flow, so that the wastewater and microorganisms are fully contacted, and the removal efficiency of pollutants is improved.

(2) The iron powder and activated carbon in the filler form an iron-carbon micro-electrolysis reaction in water, producing reduced hydrogen [H] and ferrous iron, and [H] and ferrous iron reduce part of the nitrate nitrogen to nitrogen.

(3) Iron acts as an oxygen scavenger to capture dissolved oxygen in the consumed water and create an anaerobic environment necessary for the denitrification process.

(4) Denitrifying bacteria use hydrogen and elemental sulfur as electron donors to form iron autotrophic denitrification reaction and sulfur autotrophic denitrification reaction to denitrify, reducing the addition of sulfur organic carbon sources and reducing costs. At the same time, due to the long generation cycle of autotrophic denitrifying bacteria, the amount of sludge produced is small, which avoids the occurrence of sludge bulking.

(5) Combining the iron autotrophic denitrification reaction with the sulfur autotrophic denitrification reaction, the alkali generated in the iron-carbon micro-electrolysis can have a neutralization reaction with the acid generated in the sulfur autotrophic denitrification to maintain the acid-base in the reactor. balance, so that the pH in the reactor is stabilized in a range suitable for the growth of denitrifying bacteria.

(6) When the ratio of COD concentration to nitrate nitrogen concentration in actual sewage is 3≥C/N≥1.5, the anaerobic reactor using the denitrification functional filler prepared by the present invention does not need to add additional carbon source, and can realize self- Support denitrification, the use of biochemical methods to remove nitrate nitrogen.

Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the description, claims and drawings.

Description of drawings

The accompanying drawings are used to provide a further understanding of the technical solutions of the present invention, and constitute a part of the specification. They are used to explain the technical solutions of the present invention together with the embodiments of the present application, and do not limit the technical solutions of the present invention.

Fig. 1 is the denitrification principle diagram of the denitrification functional filler of the present invention.

Figure 2. Comparison of the removal effects of conventional volcanic rock fillers and denitrification functional fillers.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that, the embodiments in the present application and the features in the embodiments may be arbitrarily combined with each other if there is no conflict.

In the embodiment of the present invention, the present invention provides a denitrification functional filler. The denitrification functional filler is composed of the following components in parts by mass: reduced iron powder 20-30%, activated carbon 8-10%, sulfur 30% -40%, metal catalyst 2-5%, binder 15-20%, pore-forming agent 3-5%, pH adjuster 3-5%.

In the embodiment of the present invention, the metal catalyst is selected from one or more of copper powder, magnesium powder, tin powder, manganese powder and titanium powder.

In the embodiment of the present invention, the binder is one or more of calcium sulfate, sodium alginate, gum arabic and polyvinyl alcohol.

In the embodiment of the present invention, the pore-forming agent is selected from one or both of ammonium bicarbonate and ammonium oxalate.

In the embodiment of the present invention, the pH adjusting agent is selected from one or more of sodium bicarbonate, sodium dihydrogen phosphate, sodium hydroxide and calcium carbonate.

In the embodiment of the present invention, the particle size of the reduced iron powder is 150-200 mesh; the particle size of the activated carbon is 150-200 mesh; the particle size of the sulfur particle is 0.5-1 mm; the particle size of the metal catalyst is 150 mesh -200 mesh.

In the embodiment of the present invention, the denitrification functional filler is a sphere with a diameter of 9-12 mm.

As shown in Figure 1, after the low C/N wastewater enters the anaerobic reactor, a part of the heterotrophic denitrifying bacteria utilizes the organic carbon source to generate a heterotrophic denitrification reaction to convert the nitrate nitrogen into nitrogen; the iron-carbon filler is in the water Iron-carbon micro-electrolysis occurs to produce [H] and ferrous iron, and nitrate nitrogen is reduced to nitrogen or ammonia nitrogen; iron-autotrophic denitrifying bacteria use the hydrogen produced by iron-carbon micro-electrolysis as an electron donor to convert nitrate nitrogen into Nitrogen; Sulfur autotrophic denitrifying bacteria convert nitrate to nitrogen using sulfur as an electron donor. At the same time, the acid produced in the sulfur autotrophic reaction is neutralized with the alkali produced in the iron autotrophic reaction, so that the pH in the water body is stabilized in a range suitable for the growth of microorganisms.

In the embodiment of the present invention, the used heterotrophic denitrifying bacteria, iron autotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria are taken from the sludge in the anaerobic concentration tank of Beijing Gaobeidian Sewage Plant.

The C/N described in the examples and comparative examples of the present invention is the ratio of COD concentration to nitrate nitrogen concentration.

Example 1

In the present embodiment, the denitrification functional filler used in the low C/N wastewater biological denitrification technology to reduce the addition of carbon sources, the preparation steps are as follows:

1) Raw material selection: the selected reduced iron powder is 200 meshes; the activated carbon is 200 meshes; the particle size of the sulfur particles is 0.5-1mm; the copper powder is 200 meshes;

2) Preparation of denitrification functional filler: mix the components according to a certain mass ratio, including 30% of reduced iron powder, 10% of activated carbon, 5% of copper powder, 30% of sulfur, 15% of calcium sulfate, and 5% of ammonium bicarbonate , sodium hydroxide 5%. Slowly add water with a mass of 15% of the mass of each component to form a viscous mixed material, fill the mixed material into a spherical mold with a particle size of 9 mm, and dry the material in a vacuum drying oven at 60 ° C for 8 hours. Then take it out of the mold, and dry it in a vacuum drying oven at 100°C to make pores to make an iron-carbon-sulfur integrated filler, that is, a denitrification functional filler.

3) Domestication and screening of dominant bacteria: C/N=1.5-2, pH=7.0, nitrate nitrogen wastewater with an influent concentration of 30±5mg/L was filled with the denitrification functional filler and sludge obtained in step 2). In the anaerobic reactor, the volume of the filler is 50% of the volume of the reactor, and the amount of sludge added is 4000mg/L. Through circulating water, it runs stably for one month, and is acclimated and screened. After screening, heterotrophic denitrifying bacteria, iron The predominant bacteria in the anaerobic reactor were trophotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria.

4) Application of denitrification functional filler: sewage is introduced into the anaerobic reactor obtained in step 3) that has been domesticated and screened for dominant bacteria. When the hydraulic retention time HRT=4h, the effluent concentration of nitrate nitrogen wastewater is 1.5-4.5mg/L, and the removal effect reaches 85-95%. The effluent SO ₄ ^2- concentration is less than 80 mg/L, and the effluent pH=6.8±0.2. Its effluent nitrate removal rate is better than other fillers.

Example 2

In the present embodiment, the denitrification functional filler used in the low C/N wastewater biological denitrification technology to reduce the addition of carbon sources, the preparation steps are as follows:

1) Raw material selection: the selected reduced iron powder is 200 mesh; the activated carbon is 200 mesh; the particle size of sulfur particles is 0.5-1 mm; the copper powder is 200 mesh; the magnesium powder is 200 mesh;

2) Preparation of denitrification functional filler: mix the components according to a certain mass ratio, including 30% of reduced iron powder, 10% of activated carbon, 3% of copper powder, 2% of magnesium powder, 30% of sulfur, and 15% of sodium alginate , ammonium bicarbonate 5%, sodium dihydrogen phosphate 5%. Slowly add water with a mass of 15% of the total mass of each component to form a viscous shape, fill the mixed material into a spherical mold with a particle size of 9 mm, dry the material in a vacuum drying box at 60 ° C for 8 hours, and then remove from the mold It is taken out of the vacuum drying box and dried at 100 °C in a vacuum drying oven to make pores to make iron-carbon-sulfur integrated fillers, that is, denitrification functional fillers.

3) Domestication and screening of dominant bacteria: C/N=1.5-2, pH=7.0, nitrate nitrogen wastewater with an influent concentration of 30±5mg/L was filled with the denitrification functional filler and sludge obtained in step 2). In the anaerobic reactor, the volume of the filler is 50% of the volume of the reactor, and the amount of sludge added is 4000mg/L. Through circulating water, it runs stably for one month, and is acclimated and screened. After screening, heterotrophic denitrifying bacteria, iron The predominant bacteria in the anaerobic reactor were trophotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria.

4) Application of denitrification functional filler: sewage is introduced into the anaerobic reactor obtained in step 3) that has been domesticated and screened for dominant bacteria. When the hydraulic retention time HRT=4h, the effluent concentration of nitrate nitrogen wastewater is 2.3-5mg/L, and the removal effect reaches 83-92%. SO ₄ ^2- concentration is less than 80mg/L, effluent pH=6.8±0.2. Its effluent nitrate removal rate is better than other fillers.

Example 3

In the present embodiment, the denitrification functional filler used in the low C/N wastewater biological denitrification technology to reduce the addition of carbon sources, the preparation steps are as follows:

1) Selection of raw materials: the selected reduced iron powder is 200 mesh; the activated carbon is 200 mesh; the particle size of sulfur particles is 0.5-1mm; the manganese powder is 200 mesh; the tin powder is 200 mesh;

2) Preparation of denitrification functional filler: mix the components according to a certain mass ratio, including 25% of reduced iron powder, 8% of activated carbon, 3% of manganese powder, 2% of tin powder, 38% of sulfur, 18% of gum arabic, Ammonium oxalate 3%, calcium carbonate 3%. Slowly add water with a mass of 15% of the total mass of each component to form a viscous shape, fill the mixed material into a spherical mold with a particle size of 9 mm, dry the material in a vacuum drying box at 60 ° C for 8 hours, and then remove from the mold It is taken out of the vacuum drying box and dried at 120 ℃ to make holes to make iron-carbon-sulfur integrated fillers, namely denitrification functional fillers.

3) Domestication and screening of dominant bacteria: C/N=1.5-2, pH=7.0, nitrate nitrogen wastewater with an influent concentration of 30±5mg/L was filled with the denitrification functional filler and sludge obtained in step 2). In the anaerobic reactor, the volume of the filler is 50% of the volume of the reactor, and the amount of sludge added is 4000mg/L. Through circulating water, it runs stably for one month, and is acclimated and screened. After screening, heterotrophic denitrifying bacteria, iron The predominant bacteria in the anaerobic reactor were trophotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria.

4) Application of denitrification functional filler: sewage is introduced into the anaerobic reactor obtained in step 3) that has been domesticated and screened for dominant bacteria. When the hydraulic retention time HRT=4h, the effluent concentration of nitrate nitrogen wastewater is 3.1-5.8mg/L, and the removal effect reaches 81-90%. The effluent SO ₄ ^2- concentration is less than 100mg/L, and the effluent pH=6.8±0.2. Its effluent nitrate removal rate is better than other fillers.

Example 4

In the present embodiment, the denitrification functional filler used in the low C/N wastewater biological denitrification technology to reduce the addition of carbon sources, the preparation steps are as follows:

1) Raw material selection: the selected reduced iron powder is 200 mesh; the activated carbon is 200 mesh; the particle size of the sulfur particles is 0.5-1mm; the titanium powder is 200 mesh; the tin powder is 200 mesh;

2) Preparation of denitrification functional filler: mix the components according to a certain mass ratio, including 30% reduced iron powder, 10% activated carbon, 3% titanium powder, 2% tin powder, 31% sulfur, and 18% polyvinyl alcohol , ammonium oxalate 3%, calcium carbonate 3%. Slowly add water with a mass of 15% of the mass of each component to form a viscous shape, fill the mixed material into a spherical mold with a particle size of 9mm, dry the material in a vacuum drying box at 45 ° C for 8 hours, and then remove from the mold It is taken out of the vacuum drying box and dried at 120 ℃ to make holes to make iron-carbon-sulfur integrated fillers, namely denitrification functional fillers.

3) Domestication and screening of dominant bacteria: C/N=1.5-2, pH=7.0, nitrate nitrogen wastewater with an influent concentration of 30±5mg/L was filled with the denitrification functional filler and sludge obtained in step 2). In the anaerobic reactor, the volume of the filler is 50% of the volume of the reactor, and the amount of sludge added is 4000mg/L. Through circulating water, it runs stably for one month, and is acclimated and screened. After screening, heterotrophic denitrifying bacteria, iron The predominant bacteria in the anaerobic reactor were trophotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria.

4) Application of denitrification functional filler: sewage is introduced into the anaerobic reactor obtained in step 3) that has been domesticated and screened for dominant bacteria. When the hydraulic retention time HRT=4h, the effluent concentration of nitrate nitrogen wastewater is 4.2-7.4mg/L, and the removal effect reaches 76-86%. The effluent SO ₄ ^2- concentration is less than 70mg/L, and the effluent pH=7.1±0.2. Its effluent nitrate removal rate is better than other fillers.

Example 5

In the present embodiment, the denitrification functional filler used in the low C/N wastewater biological denitrification technology to reduce the addition of carbon sources, the preparation steps are as follows:

1) Raw material selection: the selected reduced iron powder is 200 mesh; the activated carbon is 200 mesh; the particle size of sulfur particles is 0.5-1mm; the copper powder is 200 mesh; the magnesium powder is 200 mesh; the tin powder is 200 mesh;

2) Preparation of denitrification functional filler: All components are prepared and mixed according to a certain mass ratio, including 20% of reduced iron powder, 10% of activated carbon, 2% of copper powder, 2% of magnesium powder, 2% of tin powder, and 40% of sulfur. Calcium sulfate 15%, ammonium bicarbonate 5%, sodium hydroxide 2%, sodium dihydrogen phosphate 2%. Slowly add water with a mass of 15% of the total mass of each component to form a viscous shape, fill the mixed material into a spherical mold with a particle size of 9 mm, dry the material in a vacuum drying box at 60 ° C for 8 hours, and then remove from the mold It is taken out from the vacuum drying box and dried at 120°C in a vacuum drying oven to make pores to make iron-carbon-sulfur integrated fillers, that is, denitrification functional fillers.

3) Domestication and screening of dominant bacteria: C/N=1.5-2, pH=7.0, nitrate nitrogen wastewater with an influent concentration of 30±5mg/L was filled with the denitrification functional filler and sludge obtained in step 2). In the anaerobic reactor, the volume of the filler is 50% of the volume of the reactor, and the amount of sludge added is 4000mg/L. Through circulating water, it runs stably for one month, and is acclimated and screened. After screening, heterotrophic denitrifying bacteria, iron The predominant bacteria in the anaerobic reactor were trophotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria.

4) Application of denitrification functional filler: sewage is introduced into the anaerobic reactor obtained in step 3) that has been domesticated and screened for dominant bacteria. It is 30±5mg/L, and the dissolved oxygen concentration is 1.0-2.0mg/L. After a month of stable operation, when the hydraulic retention time HRT=4h, the effluent concentration is 3.5-5.3mg/L, and the removal effect reaches 82-88 %, the effluent SO ₄ ^2- concentration is less than 100 mg/L, and the effluent pH=6.3±0.2. Its effluent nitrate removal rate is better than other fillers.

Example 6

In the present embodiment, the denitrification functional filler used in the low C/N wastewater biological denitrification technology to reduce the addition of carbon sources, the preparation steps are as follows:

1) Raw material selection: the selected reduced iron powder is 200 mesh; the activated carbon is 200 mesh; the particle size of sulfur particles is 0.5-1mm; the copper powder is 200 mesh; the manganese powder is 200 mesh; the titanium powder is 200 mesh;

2) Preparation of denitrification functional filler: mix the components according to a certain mass ratio, including 30% of reduced iron powder, 8% of activated carbon, 2% of copper powder, 2% of manganese powder, 2% of titanium powder, and 32% of sulfur. Calcium sulfate 15%, ammonium bicarbonate 5%, sodium bicarbonate 2%, sodium dihydrogen phosphate 2%. Slowly add water with a mass of 15% of the total mass of each component to form a viscous shape, fill the mixed material into a spherical mold with a particle size of 9 mm, dry the material in a vacuum drying box at 60 ° C for 8 hours, and then remove from the mold It is taken out of the vacuum drying box and dried at 100 °C in a vacuum drying oven to make pores to make iron-carbon-sulfur integrated fillers, that is, denitrification functional fillers.

3) Domestication and screening of dominant bacteria: C/N=1.5-2, pH=7.0, nitrate nitrogen wastewater with an influent concentration of 30±5mg/L was filled with the denitrification functional filler and sludge obtained in step 2). In the anaerobic reactor, the volume of the filler is 50% of the volume of the reactor, and the amount of sludge added is 4000mg/L. Through circulating water, it runs stably for one month, and is acclimated and screened. After screening, heterotrophic denitrifying bacteria, iron The predominant bacteria in the anaerobic reactor were trophotrophic denitrifying bacteria and sulfur autotrophic denitrifying bacteria.

4) Application of denitrification functional filler: sewage is introduced into the anaerobic reactor obtained in step 3) that has been domesticated and screened for dominant bacteria, C/N=1.5-2, pH=7.0, and nitrate nitrogen concentration in the sewage. When the hydraulic retention time HRT=4h, the effluent concentration of nitrate nitrogen wastewater is 4.1-5.4mg/L, and the removal effect reaches 82-87%. The effluent SO ₄ ^2- concentration is less than 80mg/L, and the effluent pH=6.8±0.2. Its effluent nitrate removal rate is better than other fillers.

Comparative Example 1

Under the conditions of an average influent nitrate nitrogen concentration of 30mg/L, C/N=1.5-2, hydraulic retention time HRT=4h, and dissolved oxygen concentration of 1.0-2.0mg/L, in two identical reactors The conventional volcanic rock filler and the denitrification functional filler prepared in Example 3 were respectively added. The volume of the filler was 50% of the volume of the reactor. The removal effect of the reactor using conventional volcanic rock packing and packing with denitrification function is shown in Figure 2.

The dominant bacteria in the reactor using the conventional packing of volcanic rock are heterotrophic denitrifying bacteria, but when C/N=1.5-2, the living conditions of the heterotrophic bacteria are not good, which will cause the denitrification process to be incomplete and produce nitrous. Nitrogen accumulation, while denitrification effect is general.

It can be seen from Figure 2 that when using conventional volcanic rock fillers, the removal efficiency is 50%, while when using denitrification functional fillers, the removal rate can reach 85%. If the reactor with conventional volcanic rock packing is used to obtain a good removal effect, glucose is used as the carbon source, and its C/N=6.4-7.5, which is much larger than the carbon source required by the functional packing.

In the technical solution of the present invention, C/N=1.5-2, which reduces the dependence on the organic carbon source in the traditional biological denitrification process, and does not need to add an additional carbon source to the sewage.

Note that the above are only preferred embodiments of the present invention. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention. The scope is determined by the scope of the appended claims.

Claims (6)

1. The filler with the denitrification function comprises, by mass, 20-30% of reduced iron powder, 8-10% of activated carbon, 30-40% of sulfur, 2-6% of metal catalyst, 15-20% of adhesive, 3-5% of pore-forming agent, 3-5% of pH regulator and 15-20% of water accounting for the sum of the mass of the components;

the metal catalyst is selected from one or more of copper powder, magnesium powder, tin powder, manganese powder and titanium powder;

the adhesive is one or more of calcium sulfate, sodium alginate, Arabic gum and polyvinyl alcohol;

the pore-forming agent is selected from one or two of ammonium bicarbonate or ammonium oxalate;

the pH regulator is selected from one or more of sodium bicarbonate, sodium dihydrogen phosphate, sodium hydroxide and calcium carbonate;

the specific surface area of the denitrification functional filler is 245.6m²More than g.

2. The denitrification functional filler as set forth in claim 1,

the particle size of the reduced iron powder is 150-200 meshes; the particle size of the active carbon is 150-200 meshes; the particle size of the sulfur particles is 0.5-1 mm; the particle size of the metal catalyst is 150-200 meshes.

3. The denitrification functional filler according to claim 1 or 2, wherein,

the denitrification functional filler is a sphere with the diameter of 9-12 mm.

4. A method for preparing the denitrification functional filler of any one of claims 1 to 3, comprising the following steps:

the components are mixed uniformly according to the mass ratio, water accounting for 15-20% of the mass of the components is slowly added to form a viscous mixed material, the mixed material is placed in a mold, the mold is placed in a vacuum drying box for drying, and after demolding, the pore is dried in the vacuum drying box to form the denitrification functional filler.

5. The method for preparing the denitrification functional filler according to claim 4, wherein the drying conditions in the vacuum drying oven for placing the mold are 45-60 ℃ for 6-8 h;

the drying condition of drying and pore-forming in the vacuum drying oven is 100-120 ℃.

6. Use of the denitrification functional filler of any one of claims 1 to 3 in an anaerobic reactor.

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