Method for deeply removing total nitrogen in water through autotrophic-heterotrophic sulfur denitrification and application

Abstract

The invention discloses a method for deeply removing total nitrogen in water through autotrophic-heterotrophic sulfur denitrification and application, and relates to the technical field of sewage treatment deep deamination. Comprising the following steps: S1, putting a suspended sulfur carrier into a biological contact oxidation pond; s2, sulfur autotrophic denitrification strains are added into the biological contact oxidation pond, the adding amount of the strains is 2-5 kg / m < 3 > of a carrier, and stuffy aeration is conducted for 48-240 hours after water is fed; s3, after changing the water, adding a sulfur heterotrophic denitrification strain into the biological contact oxidation pond according to the addition amount of 2-3 kg / m < 3 > of the carrier, and carrying out stuffy aeration for 24-48 hours; s4, group sensing factors are added into the biological contact oxidation pond, the adding amount is 0.01-0.03 / kg / m < 3 >, and stuffy aeration is conducted for 24 h; and S5, introducing to-be-treated sewage for denitrification. According to the sewage treatment method disclosed by the invention, under the condition that the organic matter content (COD value) is relatively low, a carbon source does not need to be additionally added to remove total nitrogen, so that the effluent reaches the IV-class standard of surface water.

Description

Technical Field

[0001] The present invention relates to the technical field of deep denitrification of sewage treatment, and in particular to a method and application of deep denitrification of sulfur-containing carriers, heterotrophic sulfur microorganisms and autotrophic sulfur microorganisms. Background Art

[0002] As the country pays more and more attention to the environment, the emission standards of sewage treatment plants are becoming more and more stringent, among which total nitrogen is an indicator that is difficult for sewage treatment plants to meet. At present, in order to ensure that total nitrogen meets the standard, sewage treatment plants mostly use additional carbon sources in the denitrification process, such as acetic acid or sludge digestion liquid, waste molasses, etc. This not only increases the cost of sewage treatment, but also causes an increase in effluent COD if it is not well controlled, which in turn affects the effluent.

[0003] The removal of total nitrogen relies on denitrifying microorganisms, most of which are heterotrophic microorganisms. Autotrophic denitrifying microorganisms also exist in nature, but most of them have harsh growth conditions and are affected by carbon sources. They cannot compete with heterotrophic denitrifying microorganisms and are easily replaced by heterotrophic microorganisms when applied on a large scale. Summary of the invention

[0004] In view of this, the main purpose of the present invention is to provide a method for deep removal of total nitrogen in water by autotrophic-heterotrophic sulfur denitrification. The method combines heterotrophic and autotrophic sulfur denitrifying bacteria, uses a sulfur-containing carrier, and utilizes a quorum sensing signal molecule to rationally regulate their ecological niches, so as to achieve an autotrophic and heterotrophic combined denitrification process in a reactor, and the total nitrogen in the effluent can reach the surface water Class IV standard.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for deep removal of total nitrogen in water by autotrophic-heterotrophic sulfur denitrification comprises the following steps:

[0007] S1. Adding suspended sulfur carrier into the biological contact oxidation pond;

[0008] S2. Add sulfur autotrophic denitrifying bacteria to the biological contact oxidation pond at a dosage of 2-5 kg / m 3 Carrier, after entering the water, expose to air for 48-240 hours, and control the dissolved oxygen to be no higher than 1mg / L;

[0009] S3. After water change, add sulfur heterotrophic denitrifying bacteria to the biological contact oxidation tank at a dosage of 2-3 kg / m 3 Carrier, exposure for 24-48 hours, control the dissolved oxygen to be no higher than 1mg / L;

[0010] S4. Add quorum sensing signal molecules to the biological contact oxidation tank at a dosage of 0.01-0.03 / kg / m 3 , 24h exposure;

[0011] S5. Pass the wastewater to be treated for denitrification.

[0012] Furthermore, the suspended sulfur carrier in step S1 is prepared from sulfur powder and polyurethane, and the specific surface area of ​​the suspended sulfur carrier is not less than 2000m 2 ·m -3 The shape is a cube or a cuboid, the side length is 1.5-2.5 cm, and it can remain suspended in water. The sulfur loading capacity of the suspended sulfur carrier is 2-5 kg / m 3 Carrier volume.

[0013] Specifically, sulfur powder is mixed with polyurethane raw materials at a mass ratio of 1:10-20 for foaming, prepolymer and foaming agent are mixed under stirring at a speed of 120-170 rpm, the mixture is solidified at a certain temperature (75-85° C.) to form a carrier, and then cut into specified sizes to form a suspended sulfur carrier.

[0014] Furthermore, in step S1, the dosage of the suspended sulfur carrier is 30%-50% of the volume of the biological contact oxidation pond.

[0015] Furthermore, the biological contact oxidation tank in step S1 is a plurality of square-shaped monomer tanks.

[0016] Furthermore, the biological contact oxidation pond in step S1 is of a baffled corridor type, with a length-to-width ratio of no more than 5:1 and a width of less than 6.0 m.

[0017] Furthermore, the sulfur heterotrophic denitrifying bacteria in step S3 is selected from at least one of Thauera, Comamonas Methylotenera and Anaerolineae.

[0018] Furthermore, the sulfur autotrophic denitrifying bacteria in step S2 is selected from at least one of Thiobacillus denitrificans, Thiobacillus thiooxidans, Thiobacillus ferrooxidans, Thiobacillus novellas, Thiobacillus intermedius, and Thiobacillus perometabolis.

[0019] Furthermore, the quorum sensing signal molecule in step S4 can also be referred to as a quorum sensing factor, which is selected from at least one of C14-HSL, C6-HSL, 3-oxo-C8-HSL, and 3-oxo-C14-HSL (all of which are homoserine lactones).

[0020] C14-HSL (acyl homoserine lactone) stimulates bacterial growth, migration and protease activity, C6-HSL (N-hexanoyl-L-homoserine lactone) affects cell metabolism. 3-oxo-C8-HSL (N-(3-oxooctanoyl)-L-homoserine lactone) participates in the quorum sensing of denitrifying bacteria; (N-(3-oxotetradecanoyl)-L-homoserine lactone) is a quorum sensing inducer and participates in the mechanism of regulating quorum sensing.

[0021] Furthermore, during denitrification in step S5, the concentration of dissolved oxygen in the sewage in the device is controlled to be 0.5-0.8 mg / L, and the sewage retention time is 6-12 hours.

[0022] The denitrification load of the method for removing total nitrogen in water is 1.2-2.4 kg NO3--N / (m 3 Filler.d); the total nitrogen removal rate can reach 50-95%; the treatment depth can reach effluent TN ≤ 1.5 mg / L.

[0023] This process is suitable for sewage treatment in urban sewage treatment plants and low carbon-nitrogen ratio industrial wastewater treatment; it utilizes the combined action of autotrophic denitrifying microorganisms and autotrophic denitrifying microorganisms to remove total nitrogen from sewage.

[0024] The main features are: (1) combining the autotrophic sulfur denitrification process with the heterotrophic sulfur denitrification process to realize the conversion of total nitrogen into nitrogen gas through the autotrophic nitrification process in the reactor; (2) changing the traditional sewage treatment heterotrophic denitrification process to an autotrophic-heterotrophic denitrification process, the denitrification process can be completed without an external carbon source; (3) the process can be directly used for low carbon-nitrogen ratio sewage treatment; or directly connected to the rear end of the aerobic tank of the urban sewage treatment plant to continue to remove total nitrogen; (4) the process mainly consists of five parts: water inlet, reaction zone, effluent, aeration device, and monitoring system; (5) the main body of the reaction tank is a plug flow biological contact oxidation tank, which can be set up with different numbers of square monomer tanks according to the situation, or it can be set up as a baffled corridor type; its length-to-width ratio is not greater than 5:1, and to ensure uniform distribution of the carrier, its width should be less than 6.0m; (6) a suspended carrier is provided in the reaction tank, usually a polyurethane suspended carrier with a specific surface area of ​​not less than 2000m 2 ·m -3 The shape is a cube or a cuboid with a side length of 1.5-2.5 cm, ensuring that there are three environments: aerobic, anoxic, and facultative, and that it can remain suspended in water; (7) The process denitrification load is 1.2-2.4 kg NO3--N / (m3 Filler.d); (8) Oxygen is provided to the reactor through the aeration device to control the concentration of dissolved oxygen in the sewage in the device to be 0.5-0.8 mg / L; (9) In order to ensure the smooth progress of autonitrification and denitrification, autotrophic nitrification bacteria and autotrophic denitrification bacteria need to be added at the beginning of the reactor. The addition method is to first add autotrophic denitrification bacteria to make it grow fixedly, and then add heterotrophic denitrification bacteria to achieve the purpose of growing autotrophic denitrification bacteria inside the carrier and growing autotrophic nitrification bacteria on the surface of the carrier. Finally, add group sensing factors to control the coordinated progress of autotrophic-heterotrophic denitrification.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] (1) The sewage treatment method of the present invention can remove total nitrogen without adding additional carbon sources when the organic matter content (COD value) is low, so that the effluent meets the surface water Class IV standard.

[0027] (2) The present invention can realize the combined denitrification of heterotrophic and autotrophic microorganisms in the same reactor.

[0028] (3) The method provided by the present invention can be directly used for low carbon-nitrogen ratio sewage treatment; or directly connected to the rear end of the aerobic tank of a municipal sewage treatment plant to continue to remove total nitrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 These are naked eye observation images and scanning electron microscope scanning images of the carrier provided in the embodiments of the present invention.

[0030] Figure 2 It is the nitrogen content of the sewage entering and leaving the biological fluidized bed reactor into which the autotrophic denitrifying microbial culture solution has been placed provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0031] Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the connotation of the present invention, so the present invention is not limited to the specific implementation disclosed below.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0033] Example 1 Preparation of Suspended Sulfur Carrier

[0034] The sulfur powder and the polyurethane raw material are mixed in a ratio of 1:15 (mass ratio) for foaming, and the prepolymer and the foaming agent are added under stirring at a speed of 150 rpm. The mixed material is cured at 80°C to form a carrier, which is then cut into a suspended sulfur carrier with a side length of 1.5-2.5 cm. The specific surface area of ​​the carrier is 2500m 2 ·m -3 , sulfur loading is 2.2kg / m 3 (carrier volume), and the carrier can remain suspended in water.

[0035] The surface and internal electron microscope images are as follows Figure 1 shown.

[0036] Example 2 Cultivation of biological fluidized carrier

[0037] The 2x2 cm suspended sulfur carrier prepared in Example 1 was placed in an autotrophic denitrifying microbial culture solution (the autotrophic microbial content was not less than 2x10 10 / L) for 4 days. Then, it was placed in a culture medium for heterotrophic denitrification microorganisms for 2 days (the content of heterotrophic denitrification microorganisms was not less than 2x10 10 / L), forming a stable biological dual autotrophic carrier. Sulfur autotrophic denitrifying microorganisms include one or more of Thiobacillus denitrificans, Thiobacillus thiooxidans, Thiobacillus ferrooxidans, Thiobacillus novellas, Thiobacillus intermedius, and Thiobacillus perometabolis. In this embodiment, a mixture of Thiobacillus denitrificans, Thiobacillus thiooxidans, and Thiobacillus intermedius is specifically selected. Heterotrophic denitrifying microorganisms are one or more of Thauera, Comamonas Methylotenera, and Anaerolineae. In this embodiment, Thauera and Comamonas Methylotenera are specifically selected.

[0038] Example 3 Application of biological fluidized carrier in sewage treatment

[0039] In a sewage treatment plant, sewage enters an aerobic biological oxidation tank, and after the organic matter in the water is basically removed, it then enters an autotrophic-heterotrophic sulfur denitrification biological fluidized bed reactor, in which 40% of the cultured biological fluidized carrier (obtained in Example 2) is placed. The dissolved oxygen concentration is controlled to be 1.0 mg / L, the residence time is 6 hours, and the ammonia nitrogen and nitrate nitrogen in the inlet and outlet water are measured.

[0040] like Figure 2 As shown, the average nitrate nitrogen in the reactor inlet is 35 mg / L; the average nitrate nitrogen in the outlet is 1.2 mg / L, which meets the surface water Class IV standard. The reactor has been running stably for one year and is limited by temperature. This shows that the process can remove total nitrogen without adding new carbon sources. The sulfur-containing suspended carrier provides good living conditions for autotrophic and heterotrophic denitrifying bacteria, and the group sensing factor controls autotrophic and heterotrophic denitrification.

[0041] Example 4 Application of deep denitrification in sewage treatment plants

[0042] In a sewage treatment plant, the biological contact oxidation pond is equipped with different numbers of square single pools or baffled corridors according to the actual situation. The length-to-width ratio is not greater than 5:1. To ensure uniform distribution of carriers, the width should be less than 6.0m. The average nitrate-nitrogen content in the influent of the biological contact oxidation pond is 26.7±3.7mg / L.

[0043] At the beginning of the reactor startup, autotrophic denitrifying bacteria and heterotrophic denitrifying bacteria and group sensitivity factors need to be added at one time. First, 40% of the carrier (obtained in Example 1) is added, and then the autotrophic denitrifying bacteria are added. In this example, a mixture of denitrifying Thiobacillus, Thiobacillus thiooxidans, and Thiobacillus ferrooxidans is specifically selected, and the addition amount is 4kg / m 3 The carrier was exposed to the air for 144 hours after entering the water (the dissolved oxygen was controlled to be no higher than 1 mg / L) to allow it to grow fixedly. After changing the water, heterotrophic nitrifying bacteria were added. In this embodiment, methylotrophic Comamucoidea and anaerobic Fungi were specifically selected, and the addition amount was 2.5 kg / m 3 The carrier was exposed to air for 36 hours (the dissolved oxygen was controlled to be no higher than 1 mg / L). Finally, the group sensing factors C14-HSL and 3-oxo-C8-HSL were added, and the total amount of addition was 0.02 / kg / m 3 , and operate normally after 24 hours of aeration. Oxygen is provided to the reactor through the aeration device, and the concentration of dissolved oxygen in the sewage in the device is controlled to be between 0.5-0.8 mg / L, and the retention time is 8 hours.

[0044] The denitrification load of this process is 2.1kgNO3-N / (m 3 Filler.d); The total nitrogen removal rate reaches 95%, and the treatment depth can reach effluent TN ≤ 1.5 mg / L.

[0045] Comparative Example 1

[0046] The difference between this embodiment and embodiment 4 is that the loaded body is a ball ring packing.

[0047] In this embodiment, the total nitrogen removal rate is only 75%.

[0048] Comparative Example 2

[0049] The difference between this embodiment and embodiment 4 is that:

[0050] Without adding autotrophic sulfur denitrifying bacteria, heterotrophic sulfur denitrifying bacteria and group sensitivity factors, the reactor was started by natural biofilm formation. The operation stability of this embodiment was poor, and the total nitrogen removal rate was only 42%.

[0051] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for deep removal of total nitrogen in water by autotrophic-heterotrophic sulfur denitrification, characterized in that: The following steps are involved: S1. Adding suspended sulfur carrier into the biological contact oxidation pond; S2. Add sulfur autotrophic denitrifying bacteria to the biological contact oxidation pond at a dosage of 2-5 kg / m 3 Carrier, after entering the water, expose to air for 48-240 hours, and control the dissolved oxygen to be no higher than 1mg / L; S3. After water change, add sulfur heterotrophic denitrifying bacteria to the biological contact oxidation tank at a dosage of 2-3 kg / m 3 Carrier, suffocate and expose for 24-48 hours, control the dissolved oxygen to be no higher than 1mg / L; S4. Add quorum sensing signal molecules to the biological contact oxidation tank at a dosage of 0.01-0.03 / kg / m 3 , 24h exposure; S5. Pass the wastewater to be treated for denitrification.

2. The method according to claim 1, characterized in that The suspended sulfur carrier in step S1 is prepared from sulfur powder and polyurethane, and the specific surface area of ​​the suspended sulfur carrier is not less than 2000m 2 ·m -3 The shape is a cube or a cuboid, the side length is 1.5-2.5 cm, and it can remain suspended in water. The sulfur loading capacity of the suspended sulfur carrier is 2-5 kg / m 3 Carrier volume.

3. The method according to claim 1, characterized in that In step S1, the dosage of the suspended sulfur carrier is 30%-50% of the volume of the biological contact oxidation pond.

4. The method according to claim 1, characterized in that: The biological contact oxidation tank in step S1 is a plurality of square-shaped monomer tanks.

5. The method according to claim 1, characterized in that The biological contact oxidation pond in step S1 is of a baffled corridor type, with a length-to-width ratio of no more than 5:1 and a width of less than 6.0 m.

6. The method according to claim 1, characterized in that The sulfur heterotrophic denitrifying bacteria in step S3 are selected from at least one of the genus Tauesella, the methylotrophic Comamucella and the class Anaerobic Fungi.

7. The method according to claim 1, characterized in that The sulfur autotrophic denitrifying bacteria in step S2 are selected from at least one of Thiobacillus denitrificans, Thiobacillus thiooxidans, Thiobacillus ferrooxidans, Thiobacillus novelta, Thiobacillus intermedia and Thiobacillus metabolica incomplete.

8. The method according to claim 1, characterized in that The colony sensing signal molecule in step S4 is selected from at least one of C14-HSL, C6-HSL, 3-oxo-C8-HSL, and 3-oxo-C14-HSL.

9. The method according to claim 1, characterized in that: During denitrification in step S5, the concentration of dissolved oxygen in the sewage in the device is controlled to be 0.5-0.8 mg / L, and the sewage retention time is 6-12 hours.

10. Use of the method according to any one of claims 1 to 9 in the removal of total nitrogen from low carbon-nitrogen ratio sewage or the rear end of an aerobic tank in a municipal sewage treatment plant.

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