Method for treating nitrogen in high-nitrogen wastewater by using autotrophic denitrification

Abstract

The invention discloses a method for treating nitrogen in high-nitrogen wastewater by using autotrophic denitrification. The method comprises the following steps: S1, adjusting the pH value of to-be-treated high-nitrogen wastewater to 7.0-8.0 and the total nitrogen concentration to be less than or equal to 1000mg / L; s2, heating the high-nitrogen-content wastewater subjected to pH regulation in the step S1, and heating to 25-35 DEG C; s3, the high-nitrogen-content wastewater heated in S2 enters an autotrophic denitrification device from the bottom at a constant flow rate, the load of an autotrophic denitrification filter material is controlled to be 0.3-0.8 kgTN / t.d, and the water inlet flow rate is controlled to be 0.5-8 m / h; s4, enabling the wastewater to pass through the upper effluent of the autotrophic denitrification device to meet the treatment requirements. The method has the advantages of simple treatment process, wide application range, high load, small land occupation, no need of mechanical stirring, no need of additional organic carbon sources, extremely low sludge yield, effective reduction of the construction cost and the operation cost, and significant economic and environmental benefits.

Description

Technical Field

[0001] The invention relates to the technical field of environmental engineering, and in particular to a method for treating nitrogen in high-nitrogen wastewater by utilizing autotrophic denitrification. Background Art

[0002] In recent years, with the rapid development of the national economy, a large amount of sewage has been generated in industrial production and people's lives. The environmental problems caused by the large amount of sewage discharge are becoming increasingly serious, seriously affecting the development of the economy and society. Among them, the problem of eutrophication of water bodies is particularly prominent. Eutrophic waters can cause the massive reproduction of algae and other plankton under certain conditions, and the dissolved oxygen content of the water body drops sharply, leading to the death of fish and other organisms in large numbers, seriously affecting industrial and agricultural production and people's physical and mental health. Nitrogen discharged into the water body through sewage is recognized as one of the key factors leading to eutrophication of water bodies and should be strictly controlled.

[0003] At present, the main treatment method for denitrification in sewage treatment is biological denitrification, which mainly adopts heterotrophic denitrification, adding organic carbon sources to sewage and utilizing the denitrification of heterotrophic denitrifying bacteria to remove nitrogen. It has low volumetric load, long reaction time, large amount of organic carbon source, large amount of sludge, and increased effluent COD, which leads to high construction and operation costs and great difficulty in operation control. It is not suitable for the degradation of high-concentration nitrogen.

[0004] As a new type of biological denitrification method, autotrophic denitrification has been applied to wastewater denitrification in recent years. It is mainly based on replacing organic carbon sources with low-valent sulfur as electron donors, and denitrification is achieved through the autotrophic denitrification of autotrophic denitrifying bacteria. At present, it is mostly used for denitrification of low-nitrogen wastewater such as municipal sewage, and the total nitrogen of wastewater is generally less than 100mg / L. However, its application in high-nitrogen wastewater treatment is in urgent need of development.

[0005] To this end, the present application proposes a method for treating nitrogen in high-nitrogen wastewater using autotrophic denitrification. Summary of the invention

[0006] The purpose of the present invention is to solve the above technical problems and to propose a method for treating nitrogen in high-nitrogen wastewater by utilizing autotrophic denitrification.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for treating nitrogen in high-nitrogen wastewater by autotrophic denitrification comprises the following steps:

[0009] S1, adjusting the pH value of the high nitrogen-containing wastewater to be treated to 7.0-8.0 and the total nitrogen concentration to ≤1000 mg / L;

[0010] S2, heating the high nitrogen-containing wastewater after pH adjustment in S1 to a temperature between 25°C and 35°C;

[0011] S3, the high nitrogen-containing wastewater heated in S2 enters the autotrophic denitrification device from the bottom at a constant flow rate, the load of the autotrophic denitrification filter material is controlled to be 0.3-0.8kgTN / td, and the water inlet flow rate is controlled to be between 0.5-8m / h;

[0012] S4, the wastewater can meet the treatment requirements by passing through the upper effluent of the autotrophic denitrification device.

[0013] Preferably, before the high-nitrogen wastewater enters the autotrophic denitrification device from the bottom at a constant flow rate, autotrophic denitrification filter material and autotrophic denitrifying bacteria are added to the autotrophic denitrification device.

[0014] Preferably, the wastewater is heated by electric heating or steam heating.

[0015] Preferably, the autotrophic denitrification filter material is in irregular gravel or spherical shape, with an effective sulfur content of ≥70% and a specific surface area of ​​≥8×104cm 2 / g, bulk density is 1.1-1.2g / cm 3 .

[0016] Preferably, the autotrophic denitrifying bacteria are salt-tolerant denitrifying bacteria, with a maximum salt tolerance of not less than 3%, and a dosage of ≥1%.

[0017] Preferably, the filling amount of the autotrophic denitrification filter material is 1-3.5 m3.

[0018] Preferably, the wastewater enters and exits the autotrophic denitrification device in a bottom-in and top-out manner.

[0019] Preferably, the nitrogen in the wastewater is nitrate nitrogen or nitrite nitrogen.

[0020] Preferably, the denitrification process does not require the addition of an external carbon source and does not cause an increase in COD.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The denitrification method of the present invention is suitable for denitrification treatment of high and low concentration nitrogen-containing wastewater.

[0023] 2. The denitrification method of the present invention has a high treatment efficiency, up to 90% or more.

[0024] 3. The denitrification method of the present invention occupies less land, produces much less sludge than traditional methods, and greatly reduces construction and operating costs, with good economic efficiency.

[0025] 4. The denitrification method of the present invention does not require an external carbon source and is used to treat denitrification with an unbalanced C / N ratio.

[0026] 5. The denitrification method of the present invention does not cause an increase in COD and there is no risk of COD exceeding the standard.

[0027] 6. The denitrification method of the present invention is simple to operate and control, and the system runs more stably.

[0028] In summary, the treatment process of the present invention is relatively simple, has a wide range of applications, high load and small footprint, does not require mechanical stirring, does not require an external organic carbon source, has extremely low sludge output, effectively reduces construction costs and operating costs, and has significant economic and environmental benefits. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0030] A method for treating nitrogen in high-nitrogen wastewater by autotrophic denitrification comprises the following steps:

[0031] S1, adjusting the pH value of the high nitrogen-containing wastewater to be treated to 7.0-8.0 and the total nitrogen concentration to ≤1000 mg / L;

[0032] S2, heating the high nitrogen-containing wastewater after pH adjustment in S1 to a temperature between 25°C and 35°C;

[0033] S3, the high nitrogen-containing wastewater heated in S2 enters the autotrophic denitrification device from the bottom at a constant flow rate, the load of the autotrophic denitrification filter material is controlled to be 0.3-0.8kgTN / td, and the water inlet flow rate is controlled to be between 0.5-8m / h;

[0034] S4, the wastewater can meet the treatment requirements by passing through the upper effluent of the autotrophic denitrification device.

[0035] In the present invention, before the high-nitrogen wastewater enters the autotrophic denitrification device from the bottom at a constant flow rate, autotrophic denitrification filter material and autotrophic denitrifying bacteria are added to the autotrophic denitrification device.

[0036] In the present invention, the wastewater is heated by electric heating or steam heating.

[0037] In the present invention, the autotrophic denitrification filter material is in irregular gravel or spherical shape, with an effective sulfur content of ≥70% and a specific surface area of ​​≥8×104cm 2 / g, bulk density is 1.1-1.2g / cm 3 .

[0038] In the present invention, the autotrophic denitrifying bacteria are salt-tolerant denitrifying bacteria, with a maximum salt tolerance of not less than 3% and a dosage of ≥1%.

[0039] In the present invention, the filling amount of the autotrophic denitrification filter material is 1-3.5m3.

[0040] In the present invention, the wastewater enters and exits the autotrophic denitrification device in a bottom-in and top-out manner.

[0041] In the present invention, the nitrogen in the wastewater is nitrate nitrogen or nitrite nitrogen.

[0042] In the present invention, the denitrification process does not require the addition of an external carbon source and does not cause an increase in COD.

[0043] The embodiments of the method of the present invention are as follows:

[0044] Example 1

[0045] The wastewater produced by a chemical enterprise, nitrobenzene, has high COD and salt content, and a serious imbalance in the C / N ratio. The COD is processed by the enterprise itself in the workshop, and the salt content in the discharged wastewater is high, mainly nitrate. The specific water quality is as follows:

[0046] Water quality indicators pH Total nitrogen (mg / L) COD(mg / L) Numeric 6-7 985 1000

[0047] This method is used to denitrify the wastewater: take a certain amount of sewage to adjust the pH value between 7.0-8.0, control the temperature between 30-35℃, enter from the bottom of the primary denitrification device at a flow rate of 1L / h, stay for 48h, and the upper effluent flows into the outlet tank by gravity; control the sewage temperature of the outlet tank between 30-35℃, enter from the bottom of the secondary denitrification device at a flow rate of 1L / h, stay for 28h, and filter the upper effluent for testing. The total nitrogen in the effluent is 18.3mg / L, and the removal rate is 98%.

[0048] Example 2

[0049] The wastewater of a certain electroplating enterprise has a high total nitrogen content, and is mainly nitrate nitrogen. The specific water quality is as follows:

[0050] Water quality indicators pH Total nitrogen (mg / L) Ammonia nitrogen (mg / L) Numeric 7.0 150.54 18.18

[0051] This method is used to denitrify the wastewater: a certain amount of sewage is taken to adjust the pH value between 7.0-8.0, the temperature is controlled between 30-35℃, and it enters the bottom of the denitrification device at a flow rate of 6L / h, the residence time is 12h, and the upper effluent is filtered and tested. The total nitrogen in the effluent is 22.7mg / L, the ammonia nitrogen is 17.5mg / L, the nitrate nitrogen removal rate is 96%, and the effluent meets the discharge requirements (total nitrogen ≤70mg / L).

[0052] Example 3

[0053] The wastewater of a pharmaceutical enterprise has high nitrate content, high total nitrogen content, low COD content, and a serious imbalance in the C / N ratio. The specific water quality is as follows:

[0054] Water quality indicators Nitrate (mg / L) Total nitrogen (mg / L) COD(mg / L) Numeric 15511 3500 660 After dilution / 993 198

[0055] This method is applied to denitrify the wastewater: take a certain amount of wastewater to adjust the pH value between 7.0-8.0, control the temperature between 30-35℃, enter from the bottom of the primary denitrification device at a flow rate of 1L / h, stay for 48h, and the upper effluent flows into the outlet tank by gravity; control the sewage temperature of the outlet tank between 30-35℃, enter from the bottom of the secondary denitrification device at a flow rate of 0.85L / h, stay for 32h, and filter the upper effluent for testing. The total nitrogen in the effluent is 23mg / L, the removal rate is 97.7%, and the effluent meets the discharge requirements (total nitrogen ≤40mg / L).

[0056] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for treating nitrogen in high-nitrogen wastewater using autotrophic denitrification, characterized in that: The following steps are involved: S1, adjusting the pH value of the high nitrogen-containing wastewater to be treated to 7.0-8.0 and the total nitrogen concentration to ≤1000 mg / L; S2, heating the high nitrogen-containing wastewater after pH adjustment in S1 to a temperature between 25°C and 35°C; S3, the high nitrogen-containing wastewater heated in S2 enters the autotrophic denitrification device from the bottom at a constant flow rate, the load of the autotrophic denitrification filter material is controlled to be 0.3-0.8kgTN / td, and the water inlet flow rate is controlled to be between 0.5-8m / h; S4, the wastewater can meet the treatment requirements by passing through the upper effluent of the autotrophic denitrification device.

2. The method for treating nitrogen in high-nitrogen wastewater by autotrophic denitrification according to claim 1, characterized in that: Before the high-nitrogen wastewater enters the autotrophic denitrification device from the bottom at a constant flow rate, autotrophic denitrification filter material and autotrophic denitrifying bacteria are added to the autotrophic denitrification device.

3. The method for treating nitrogen in high-nitrogen wastewater by autotrophic denitrification according to claim 1, characterized in that: The wastewater is heated by electric heating or steam heating.

4. The method for treating nitrogen in high-nitrogen wastewater by autotrophic denitrification according to claim 2, characterized in that: The autotrophic denitrification filter material is in irregular gravel or spherical shape, with an effective sulfur content of ≥70% and a specific surface area of ​​≥8×104cm 2 / g, bulk density is 1.1-1.2g / cm 3 .

5. The method for treating nitrogen in high-nitrogen wastewater by autotrophic denitrification according to claim 2, characterized in that: The autotrophic denitrifying bacteria are salt-tolerant denitrifying bacteria, with a maximum salt tolerance of not less than 3% and a dosage of ≥1%.

6. The method for treating nitrogen in high-nitrogen wastewater by autotrophic denitrification according to claim 1, characterized in that: The filling amount of the autotrophic denitrification filter material is 1-3.5m3.

7. The method for treating nitrogen in high-nitrogen wastewater by autotrophic denitrification according to claim 1, characterized in that: The wastewater enters and exits the autotrophic denitrification device in a bottom-in and top-out manner.

8. The method for treating nitrogen in high-nitrogen wastewater by autotrophic denitrification according to claim 1, characterized in that: The nitrogen in the wastewater is nitrate nitrogen or nitrite nitrogen.

9. The method for treating nitrogen in high-nitrogen wastewater by autotrophic denitrification according to claim 1, characterized in that: The denitrification process does not require an external carbon source and does not cause an increase in COD.