A membrane carrier detachable municipal tail water nitrate nitrogen deep removal pipe and its integrated application method

Abstract

The present invention discloses a membrane carrier detachable municipal tail water nitrate nitrogen deep removal pipe and its integrated application method, including a pool body, a switchable nitrate nitrogen deep removal pipeline, a diffusion device, a switchable water outlet, and a switchable water inlet; the switchable nitrate nitrogen deep removal pipeline is parallel to the width side and is located in the center of the pool body, and is composed of a pipe body, a plurality of card slots and a plurality of membrane carriers. The present invention does not require additional carbon source addition, reduces operating costs, and avoids secondary pollution caused by excessive carbon source input and its metabolism; meets the requirements of upgrading and transformation, and has a good treatment effect; the device is detachable and easy to maintain, and the membrane carrier can be removed from the pipeline, which is convenient for replacement when it fails or is damaged. The membrane carrier that has formed a film in situ can be replaced without waiting for the replaced membrane carrier to form a film, and the treatment effect can be kept stable for a long time, and is also suitable for emergency treatment of nitrate nitrogen pollution in water bodies.

Description

Technical Field

[0001] The invention relates to the technical field of municipal tail water treatment, in particular to a membrane carrier detachable municipal tail water nitrate nitrogen deep removal pipe and an integrated application method thereof. Background Art

[0002] In 2021, the national sewage discharge volume reached 62.5 billion cubic meters, and a total of 2,827 sewage treatment plants were built. The annual sewage discharge volume has increased rapidly year by year. These treated sewage are called municipal tailwater, which must meet the "Level A" standard of the "Pollutant Discharge Standard for Urban Sewage Treatment Plants" (GB 18918-2002) before it can be discharged. Among them, the pollutants in municipal tailwater are mainly nitrate nitrogen, with a concentration of about 15 mg / L. The discharge of nitrogen not only leads to eutrophication of water bodies, but also easily converts into carcinogenic nitrite, which seriously endangers human health and safety.

[0003] On the one hand, the standard reached when municipal tailwater is discharged (total nitrogen: 15 mg / L) is far from the minimum standard of the receiving water body (Surface Water Environmental Quality Standard (GB 3838-2002) Class V, total nitrogen: 2.0 mg / L). The vast majority of municipal tailwater is directly discharged into surface water after treatment. Due to the huge difference in pollutant concentrations, municipal tailwater has become a source of pollution for surface water, which is easy to cause damage to the surface water environment and ecosystem. On the other hand, upgrading and transformation is the general trend of the development of sewage treatment plants and the latest requirement of the country. In response to this, Beijing, Tianjin, Jiangsu, Zhejiang and other places have formulated more stringent sewage discharge standards (Table 1) based on the local economic and technological level and the environmental capacity of the receiving water body, especially for total nitrogen (TN), ammonia nitrogen (NH3-N) and other indicators. Higher requirements have been put forward, and local sewage treatment plants are required to upgrade and transform, and deeply treat municipal tailwater to achieve quasi-Class IV to V discharge standards.

[0004] Table 1 Requirements for total nitrogen in local water pollutant emission standards

[0005]

[0006]

[0007] The current method of removing nitrate nitrogen is mainly based on the principle of denitrification, that is, relying on exogenous carbon sources as electron donors to convert nitrate nitrogen into nitrogen gas for denitrification. At present, most sewage treatment plants deeply denitrify tailwater by setting up denitrifying biofilters, artificial wetlands and denitrifying moving bed biofilm reactors. The denitrifying biofilter metabolizes organic carbon sources through the denitrifying bacteria attached to the surface of the filter material to carry out the denitrification process, but it needs to be backwashed to drive nitrogen during operation, which is complicated to operate and has high energy consumption. Using the rhizosphere adsorption of artificial wetlands for denitrification is also a common method in sewage treatment plants. However, the construction of artificial wetlands requires a large area of ​​land, and its treatment effect is unstable and easily affected by seasonal factors. The denitrifying moving bed biofilm reactor promotes the proliferation of microorganisms on the carrier under stirring to form a denitrifying biofilm, but the carrier required by the reactor is expensive, difficult to clean after use, and causes secondary pollution after abandonment. The invention patent with application number 201910871213.4 discloses "a denitrification biological turntable for urban sewage denitrification". The invention designs a turntable structure to enrich the electroactive biofilm and adopts the principle of electrochemical denitrification. It does not require the addition of carbon source for denitrification. However, this structure is difficult to operate and maintain. For example, when a metal fan blade is damaged, the entire turntable needs to be replaced. In addition, before the invention is used, it is necessary to enrich microorganisms on the metal fan blades in situ to form an electroactive biofilm. This process takes about 1 to 2 weeks, and the acclimation period is relatively long.

[0008] Therefore, for municipal tail water, there is an urgent need for a tail water deep denitrification equipment that requires no carbon source input, is easy to maintain, and has simple settings to meet the requirements of upgrading sewage treatment plants and linking with municipal tail water and surface water standards. Summary of the invention

[0009] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and to provide a membrane carrier-detachable municipal tail water nitrate-nitrogen deep removal pipe and an integrated application method thereof. The membrane carrier-detachable municipal tail water nitrate-nitrogen deep removal pipe and an integrated application method thereof can not only perform deep denitrification of municipal tail water without carbon source input, meeting the requirements of upgrading and transformation, but also have simple configuration and easy maintenance. The detachable membrane carrier has the characteristics of rapid enrichment of microorganisms, and the damaged membrane carrier can be replaced after ex situ domestication.

[0010] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0011] A membrane carrier detachable municipal tail water nitrate nitrogen deep removal pipe comprises a tank body, a switchable nitrate nitrogen deep removal pipeline, a diffusion device, a switchable water outlet hole, and a switchable water inlet hole.

[0012] The pool body is a rectangular pool constructed of concrete with a length-to-width ratio of 1 to 1.5.

[0013] The switchable nitrate nitrogen deep removal pipeline is parallel to the width side and is located in the center of the pool body, and comprises a pipe body, a plurality of slots and a plurality of membrane carriers.

[0014] The tube body is made of PVC, the tube thickness is 1cm, and it can be opened from the side to facilitate replacement of the membrane carrier.

[0015] A plurality of card slots are arranged on the inner side of the tube body, the width of the card slots is equal to the thickness of the membrane carrier, the depth of the card slots is 0.5 cm, and the number of the card slots is equal to the number of the membrane carriers.

[0016] Several membrane carriers are fixed in the tube body through several slots, including 2 stainless steel meshes, 1 biochemical cotton and several metal nails. The stainless steel meshes are placed on both sides of the biochemical cotton, aligned parallel to the biochemical cotton, and fixed with several metal nails. Each stainless steel mesh is 0.1 cm thick and has 100 meshes. Each biochemical cotton is 0.3 cm thick.

[0017] The diffusion equipment is placed on both sides of the switchable nitrate nitrogen deep removal pipeline at the water inlet and outlet to control the water flow speed and direction.

[0018] The switchable water outlet holes are located at the upper positions on both sides of the pool body.

[0019] The switchable water inlet hole is located below the switchable water outlet hole.

[0020] An integrated application method of a membrane carrier detachable municipal tail water nitrate nitrogen deep removal pipe comprises the following steps.

[0021] Step 1: Set up membrane carriers in series: Determine the number of membrane carriers according to the effluent water quality requirements and power them in series mode.

[0022] Step 11: Determine the minimum supply current I min :This method adopts the electrochemical denitrification method, which directly provides electrons to the denitrification reaction on the membrane carrier through electric current, without the input of external carbon source, saving energy and avoiding secondary pollution. In addition, in order to ensure the growth of electroactive biofilm, the current density J of the membrane carrier is min Not less than 5A / m 2 , minimum supply current I min The calculation formula is as follows:

[0023] I min =0.25πd 2 J min ①

[0024] Where, d represents the inner diameter of the switchable nitrate nitrogen deep removal pipeline, J min Indicates the minimum current density of the membrane carrier.

[0025] Step 12: Determine the number n of membrane carriers by the following formula:

[0026]

[0027] Where k represents the number of electrons transferred in the electrochemical denitrification reaction; F represents the Faraday constant; V represents the volume of municipal tailwater to be treated; C 初始 represents the initial nitrate nitrogen concentration; C 目标 represents the target concentration of nitrate nitrogen after treatment; I represents the supply current; t represents the hydraulic retention time; M N Represents the relative atomic mass of nitrogen.

[0028] Step 2: Enrichment of electroactive microorganisms to form electroactive biofilm: Enrichment of electroactive microorganisms on the membrane carrier, the middle layer of biochemical cotton promotes the adsorption of microorganisms by the membrane carrier, and the electroactive biofilm is formed on the stainless steel mesh. Based on the detachable characteristics of the membrane carrier, this process can form an electroactive biofilm in situ in the tube, or it can be set up in a culture pool to form a film ex situ and then moved to the tube.

[0029] Step 3: Introduce municipal tail water: Open the switchable water inlet hole and introduce the municipal tail water to be treated; turn on the diffusion equipment to allow the water in the pool to circulate in the pool in the specified direction.

[0030] Step 4: Long-term stable treatment of municipal tail water: The electroactive biofilm dominated by electroactive microorganisms has the ability to directly metabolize electrons, and supplies electricity to the membrane carrier in the tube through the cathode of the external circuit, directly providing electrons for the denitrification reaction on the membrane carrier, which can effectively remove nitrate nitrogen from the tail water. When the membrane carrier is damaged during long-term operation, it can be replaced with a membrane carrier that has formed an electroactive biofilm ectopically, which is convenient for equipment maintenance and beneficial for long-term stable treatment of municipal tail water.

[0031] The present invention has the following beneficial effects:

[0032] 1. No additional carbon source is required, which reduces operating costs and avoids secondary pollution caused by excessive carbon source and its metabolism. The present invention enriches microorganisms on the membrane carrier to form an electroactive biofilm dominated by electroactive microorganisms, connects the cathode of the external circuit to the membrane carrier, directly provides electrons, replaces the exogenous carbon source to supply denitrifying bacteria, so that nitrate nitrogen is converted into nitrogen gas, and completes the denitrification process.

[0033] 2. It meets the requirements of upgrading and transformation, and has good treatment effect. The electrons provided by the cathode of the external circuit move very quickly, and can provide a large number of electrons for the denitrification reaction in a short time. The electroactive biofilm formed on the membrane carrier also has a strong metabolic ability for electrons, which can quickly remove a large amount of nitrate nitrogen and efficiently treat municipal tail water.

[0034] 3. The device is detachable and easy to maintain. The membrane carrier can be removed from the pipeline, which is convenient for replacement when it fails or is damaged. The membrane carrier that has formed a membrane in situ can be replaced without waiting for the replaced membrane carrier to form a membrane. The treatment effect can be kept stable for a long time and it is also suitable for emergency treatment of nitrate nitrogen pollution in water bodies. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The schematic diagram of the structure of a detachable membrane carrier municipal tail water nitrate nitrogen deep removal pipe of the present invention is shown.

[0036] Figure 2 A schematic diagram of the integrated application of the present invention is shown.

[0037] Figure 3 A schematic diagram of the water flow direction when the present invention is in operation is shown.

[0038] Figure 4 The relationship between the number of membrane carriers of the present invention and the hydraulic retention time is shown.

[0039] Among them are:

[0040] 1. Pool body; 2. Switchable nitrate nitrogen deep removal pipeline, 21. Pipe body, 22. Card slot, 23. Membrane carrier; 3. Diffusion device; 4. Switchable water outlet hole; 5. Switchable water inlet hole. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific preferred embodiments.

[0042] In the description of the present invention, it should be understood that the terms "left side", "right side", "upper part", "lower part" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. "First", "second" and the like do not indicate the importance of the components, and therefore cannot be understood as limiting the present invention. The specific dimensions used in this embodiment are only for illustrating the technical solution, and do not limit the scope of protection of the present invention.

[0043] like Figure 1 , 2 As shown, a membrane carrier detachable municipal tail water nitrate nitrogen deep removal pipe includes a tank body 1, a switchable nitrate nitrogen deep removal pipeline 2, a diffusion device 3, a switchable water outlet 4, and a switchable water inlet 5.

[0044] The pool body is a rectangular pool constructed of concrete with a length-to-width ratio of 1 to 1.5.

[0045] The switchable nitrate nitrogen deep removal pipeline is located in the center of the pool body parallel to the width side, including a tube body 21, a plurality of slots 22 and a plurality of membrane carriers 23. The tube body is made of PVC, with a thickness of 1 cm, and can be opened from the side to facilitate the replacement of the membrane carrier. A plurality of slots are arranged on the inner side of the tube body, the width of the slot is equal to the thickness of the membrane carrier, the depth of the slot is 0.5 cm, and the number of slots is equal to the number of membrane carriers. A plurality of membrane carriers are fixed in the tube body through a plurality of slots, including 2 pieces of stainless steel mesh, 1 piece of biochemical cotton and a plurality of metal nails. The stainless steel mesh is placed on both sides of the biochemical cotton, aligned parallel to the biochemical cotton, and fixed with a plurality of metal nails. Each piece of stainless steel mesh is 0.1 cm thick and has 100 meshes. Each piece of biochemical cotton is 0.3 cm thick.

[0046] The diffusion equipment is placed on both sides of the switchable nitrate nitrogen deep removal pipeline at the water inlet and outlet to control the water flow speed and direction.

[0047] The switchable water outlet holes are located at the upper positions on both sides of the pool body.

[0048] The switchable water inlet hole is located below the switchable water outlet hole.

[0049] The specific mechanism of action of the present invention is as follows:

[0050] (1) Replace the exogenous carbon source, the external circuit directly provides electrons to the denitrification process, efficiently provides electrons, reduces costs, and avoids secondary pollution

[0051] The cathode of the external circuit is connected to the membrane carrier, which directly supplies electrons to the denitrification process and avoids the addition of exogenous carbon sources. The membrane carrier consists of 2 pieces of stainless steel mesh and 1 piece of biochemical cotton. The biochemical cotton has adsorption properties and can attract a large number of microorganisms to enrich on the surface of the stainless steel mesh. Under the stimulation of electric current, an electroactive biofilm dominated by electroactive microorganisms is formed. Electroactive microorganisms have the ability to directly metabolize the electrons supplied by the external circuit, and the aggregates (electroactive biofilms) formed can quickly convert nitrate nitrogen into nitrogen gas.

[0052] (2) The membrane carrier is detachable and easy to replace. It can enrich microorganisms in situ or ex situ to form an electroactive biofilm, which can maintain the long-term efficient and stable denitrification of the equipment. It can also be used as an emergency pollution treatment equipment.

[0053] The membrane carrier is fixed in the tube body by a slot, and has the characteristics of being detachable and replaceable. Therefore, at the initial startup, if the acclimation time is not considered, it is possible to choose to enrich the microorganisms in situ to form an electroactive biofilm; if it is necessary to run the present invention quickly, it is possible to choose to place the membrane carrier that has formed a film ex situ in the tube body. In addition, in the long-term operation of the equipment, damage to the membrane carrier is an unavoidable problem. A damaged membrane carrier will lead to a decrease in the denitrification capacity of the equipment, and replacing the membrane carrier as a whole before running it requires a lot of acclimation and film formation time, and wastes a lot of financial and human resources. The detachable design of a single membrane carrier of the present invention allows it to be replaced with a membrane carrier that has been acclimated ex situ to form a film after damage, thereby maintaining the long-term stability of the denitrification effect of the present invention, and can be used as an emergency nitrate nitrogen pollution treatment equipment.

[0054] An integrated application method of a membrane carrier detachable municipal tail water nitrate nitrogen deep removal pipe comprises the following steps.

[0055] Step 1: Set up membrane carriers in series: Determine the number of membrane carriers according to the effluent water quality requirements and power them in series mode.

[0056] Step 11: Determine the minimum supply current I min :This method adopts the electrochemical denitrification method, which directly provides electrons to the denitrification reaction on the membrane carrier through electric current, without the input of external carbon source, saving energy and avoiding secondary pollution. In addition, in order to ensure the growth of electroactive biofilm, the current density J of the membrane carrier is min Not less than 5A / m 2 , minimum supply current I min The calculation formula is as follows:

[0057] I min =0.25πd 2 J min ①

[0058] Where, d represents the inner diameter of the switchable nitrate nitrogen deep removal pipeline, J min Indicates the minimum current density of the membrane carrier.

[0059] Step 12: Determine the number n of membrane carriers by the following formula:

[0060]

[0061] Where k represents the number of electrons transferred in the electrochemical denitrification reaction; F represents the Faraday constant; V represents the volume of municipal tailwater to be treated; C 初始 represents the initial nitrate nitrogen concentration; C 目标 represents the target concentration of nitrate nitrogen after treatment; I represents the supply current; t represents the hydraulic retention time; M N Represents the relative atomic mass of nitrogen.

[0062] Step 2: Enrichment of electroactive microorganisms to form electroactive biofilm: Enrichment of electroactive microorganisms on the membrane carrier, the middle layer of biochemical cotton promotes the adsorption of microorganisms by the membrane carrier, and the electroactive biofilm is formed on the stainless steel mesh. Based on the detachable characteristics of the membrane carrier, this process can form an electroactive biofilm in situ in the tube, or it can be set up in a culture pool to form a film ex situ and then moved to the tube.

[0063] Step 3: Introduce municipal tail water: Open the switchable water inlet hole and introduce the municipal tail water to be treated; turn on the diffusion device to make the water in the pool circulate in the pool in the specified direction (such as Figure 3 shown).

[0064] Step 4: Long-term stable treatment of municipal tail water: The electroactive biofilm dominated by electroactive microorganisms has the ability to directly metabolize electrons, and supplies electricity to the membrane carrier in the tube through the cathode of the external circuit, directly providing electrons for the denitrification reaction on the membrane carrier, which can effectively remove nitrate nitrogen from the tail water. When the membrane carrier is damaged during long-term operation, it can be replaced with a membrane carrier that has formed an electroactive biofilm ectopically, which is convenient for equipment maintenance and beneficial for long-term stable treatment of municipal tail water.

[0065] The nitrogen element in the tail water is basically present in the form of nitrate nitrogen, so in the embodiment of the present invention, it can be considered that the total nitrogen content is equal to the nitrate nitrogen content.

[0066] Example 1: Achieving Standard A of Jiangsu Province's "Pollutant Emission Standards for Urban Sewage Treatment Plants" (Draft for Approval)

[0067] Taking the use of the present invention to treat 10t of municipal tail water to meet Standard A of Jiangsu Province's "Pollutant Discharge Standards for Urban Wastewater Treatment Plants" (draft for approval) as an example, the initial nitrate nitrogen concentration is 15mg / L, and the target concentration of nitrate nitrogen after treatment is 12mg / L.

[0068] The pool body is designed to be 8m long, 6m wide and 1.2m high, and the inner diameter of the switchable nitrate nitrogen deep removal pipeline is 1m.

[0069] Membrane carriers are set up in series:

[0070] (1) Determine the minimum supply current I min : Minimum supply current I min The calculation formula is as follows:

[0071] I min =0.25πd 2 J min ①

[0072] Where, d represents the switchable nitrate nitrogen depth removal pipeline with an inner diameter of 1m, J min Indicates that the minimum current density of the membrane carrier is 5A / m 2.

[0073] Therefore, the power supply current in this embodiment should be no less than 3.9A, and in this example, 4A is used.

[0074] (2) Determine the number n of membrane carriers by the following formula:

[0075]

[0076] In the formula, k represents the number of electrons transferred in the electrochemical denitrification reaction, which is 5; F represents the Faraday constant, which is 96485C / mol; V represents the volume of municipal tailwater to be treated, which is 10m 3 ; C 初始 Indicates that the initial nitrate nitrogen concentration is 15 mg / L; C 目标 indicates that the target concentration of nitrate nitrogen after treatment is 12 mg / L; I indicates that the power supply current is 4A; t indicates that the hydraulic retention time is 2h; M N The relative atomic mass of nitrogen is 14.

[0077] According to formula ②, the number of membrane carriers in this embodiment is 36, and 36 slots need to be set in the tube.

[0078] Enriching electroactive microorganisms to form electroactive biofilms: In this embodiment, there is no need to quickly start the equipment, and a membrane carrier is selected to in situ enrich electroactive microorganisms to form electroactive biofilms.

[0079] (1) Place the new membrane carrier in a switchable nitrate nitrogen deep removal pipeline, connect it in series with the cathode of the external circuit, and supply 3.9A current (I min ).

[0080] (2) The pipe is filled with municipal tail water. Under the stimulation of electric current and the adsorption of biochemical cotton, the electroactive microorganisms in the tail water are enriched on the stainless steel mesh of the membrane carrier. After colonization and proliferation, they evolve into mature electroactive biofilms. This process takes about 10 to 14 days.

[0081] Introduce municipal tail water: Open the switchable water inlet hole to introduce the municipal tail water to be treated; turn on the diffusion equipment to make the water in the pool flow in the specified direction ( Figure 3 ) circulates in the pool.

[0082] Long-term and stable treatment of municipal tail water: When the membrane carrier is damaged during long-term operation, it can be replaced with a membrane carrier that has formed an electroactive biofilm ectopically to maintain the treatment effect of the equipment.

[0083] Example 2: Meeting Class V Standard of Surface Water Environmental Quality Standard (GB 3838-2002)

[0084] In order to make the municipal tail water closer to the surface water quality and avoid damaging the surface water ecological environment, taking the use of the present invention to treat 10t of municipal tail water to meet the Class V standard of the "Surface Water Environmental Quality Standard" (GB 3838-2002) as an example, the initial nitrate nitrogen concentration is 15mg / L, and the target concentration of nitrate nitrogen after treatment is 2mg / L.

[0085] In this embodiment, the hydraulic retention time is extended from 2 hours to 3 hours, the current electron supply is improved, and the number of membrane carriers in the switchable nitrate nitrogen deep removal pipeline is increased to meet the treatment requirements of this example.

[0086] The pool body is designed to be 8m long, 8m wide and 1.2m high, and the inner diameter of the switchable nitrate nitrogen deep removal pipeline is 1m.

[0087] Membrane carriers are set up in series:

[0088] (1) Determine the minimum supply current I min : Minimum supply current I min The calculation formula is as follows:

[0089] I min =0.25πd 2 J min ①

[0090] Where, d represents the switchable nitrate nitrogen depth removal pipeline with an inner diameter of 1m, J min Indicates that the minimum current density of the membrane carrier is 5A / m 2 .

[0091] Therefore, the power supply current in this embodiment should be no less than 3.9A, and in this example, 10A is taken.

[0092] (2) Determine the number n of membrane carriers by the following formula:

[0093]

[0094] In the formula, k represents the number of electrons transferred in the electrochemical denitrification reaction, which is 5; F represents the Faraday constant, which is 96485C / mol; V represents the volume of municipal tailwater to be treated, which is 10m 3 ; C 初始 Indicates that the initial nitrate nitrogen concentration is 15 mg / L; C 目标 indicates that the target concentration of nitrate nitrogen after treatment is 2 mg / L; I indicates that the power supply current is 10 A; t indicates that the hydraulic retention time is 3 h; M N The relative atomic mass of nitrogen is 14.

[0095] According to formula ②, the number of membrane carriers in this embodiment is 42, and 42 slots need to be set in the tube.

[0096] Enriching electroactive microorganisms to form electroactive biofilms: In this embodiment, there is no need to quickly start the equipment, and a membrane carrier is selected to in situ enrich electroactive microorganisms to form electroactive biofilms.

[0097] (1) Place the new membrane carrier in a switchable nitrate nitrogen deep removal pipeline, connect it in series with the cathode of the external circuit, and supply 3.9A current (I min ).

[0098] (2) The pipe is filled with municipal tail water. Under the stimulation of electric current and the adsorption of biochemical cotton, the electroactive microorganisms in the tail water are enriched on the stainless steel mesh of the membrane carrier. After colonization and proliferation, they evolve into mature electroactive biofilms. This process takes about 10 to 14 days.

[0099] Introduce municipal tail water: Open the switchable water inlet hole to introduce the municipal tail water to be treated; turn on the diffusion equipment to make the water in the pool flow in the specified direction ( Figure 3 ) circulates in the pool.

[0100] Long-term and stable treatment of municipal tail water: When the membrane carrier is damaged during long-term operation, it can be replaced with a membrane carrier that has formed an electroactive biofilm ectopically to maintain the treatment effect of the equipment.

[0101] Example 3: Emergency treatment of nitrate nitrogen pollution in surface water

[0102] In order to deal with the situation where the sewage treatment plant has insufficient treatment capacity or the surface water is directly discharged with pollutants, the following emergency treatment scheme for nitrate nitrogen pollution in surface water is designed. Taking the treatment of 1 ton of sewage by the present invention as an example, the initial nitrate nitrogen concentration is 20 mg / L, and the target concentration of nitrate nitrogen after treatment is 2 mg / L.

[0103] The design directly places the switchable deep nitrate nitrogen removal pipeline in the river channel or sets it near the river channel. The inner diameter of the switchable deep nitrate nitrogen removal pipeline is 1m.

[0104] Membrane carriers are set up in series:

[0105] (1) Determine the minimum supply current I min : Minimum supply current I min The calculation formula is as follows:

[0106] I min =0.25πd 2 J min ①

[0107] Where, d represents the switchable nitrate nitrogen depth removal pipeline with an inner diameter of 1m, J min Indicates that the minimum current density of the membrane carrier is 5A / m 2 .

[0108] Therefore, the power supply current in this embodiment should be no less than 3.9A, and in this example, 10A is taken.

[0109] (2) Determining the number n of membrane carriers: In emergency treatment, the membrane carrier arrangement of the present invention is limited by the site and has high requirements for hydraulic retention time. Therefore, in actual treatment, Figure 4 Determine the number n of membrane carriers.

[0110] Enriching electroactive microorganisms to form electroactive biofilms: This embodiment requires rapid startup of the device, selecting a membrane carrier that has formed a film ectopically and placing it in the tube body, and the method for forming the membrane carrier is as described above.

[0111] Pass sewage in: Pass sewage directly into the switchable nitrate nitrogen deep removal pipeline.

[0112] Long-term and stable treatment of municipal tail water: When the membrane carrier is damaged during long-term operation, it can be replaced with a membrane carrier that has formed an electroactive biofilm ectopically to maintain the treatment effect of the equipment.

[0113] The preferred embodiments of the present invention are described in detail above; however, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all belong to the protection scope of the present invention.

Claims

1. A membrane carrier detachable municipal tail water nitrate nitrogen deep removal pipe, characterized in that: It includes a pool body, a switchable nitrate nitrogen deep removal pipeline, a diffusion device, a switchable water outlet, and a switchable water inlet; The pool is a rectangular pool constructed of concrete with a length-to-width ratio of 1 to 1.5; The switchable nitrate nitrogen deep removal pipeline is located in the center of the tank parallel to the width side; The switchable nitrate nitrogen deep removal pipeline comprises a pipe body, a plurality of card slots and a plurality of membrane carriers; A plurality of membrane carriers are fixed in the tube body through a plurality of slots, and the membrane carriers include 2 stainless steel meshes, 1 biochemical cotton and a plurality of metal nails; the stainless steel meshes are respectively placed on both sides of the biochemical cotton, aligned parallel to the biochemical cotton, and fixed with a plurality of metal nails; each stainless steel mesh is 0.1 cm thick, and has 100 meshes; each biochemical cotton is 0.3 cm thick; The diffusion equipment is placed on both sides of the water inlet and outlet of the switchable nitrate nitrogen deep removal pipeline to control the water flow speed and direction; The switchable water outlets are located at the upper part of both sides of the pool body; The switchable water inlet hole is located below the switchable water outlet hole.

2. The membrane carrier detachable municipal tail water nitrate nitrogen deep removal pipe according to claim 1, characterized in that: The tube body is made of PVC, the tube thickness is 1cm, and it can be opened from the side to facilitate replacement of the membrane carrier.

3. The membrane carrier detachable municipal tail water nitrate nitrogen deep removal pipe according to claim 1, characterized in that: A plurality of card slots are arranged on the inner side of the tube body, the width of the card slots is equal to the thickness of the membrane carrier, the depth of the card slots is 0.5 cm, and the number of the card slots is equal to the number of the membrane carriers.

4. The integrated application method of the membrane carrier detachable municipal tail water nitrate nitrogen deep removal pipe according to any one of claims 1 to 3, characterized in that: The steps include: Step 1: Set up membrane carriers in series: determine the number of membrane carriers according to the effluent water quality requirements, and power them in series mode; Step 11: Determine the minimum supply current I min :This method adopts the electrochemical denitrification method, which directly provides electrons to the denitrification reaction on the membrane carrier through electric current, without the input of external carbon source, saving energy and avoiding secondary pollution; in addition, in order to ensure the growth of electroactive biofilm, the current density J of the membrane carrier is min Not less than 5A / m 2 , minimum supply current I min The calculation formula is as follows: I min =0.25πd 2 J min Where, d represents the inner diameter of the switchable nitrate nitrogen deep removal pipeline, J min Indicates the minimum current density of the membrane carrier; Step 12: Determine the number n of membrane carriers by the following formula: Where k represents the number of electrons transferred in the electrochemical denitrification reaction; F represents the Faraday constant; V represents the volume of municipal tailwater to be treated; C 初始 represents the initial nitrate nitrogen concentration; C 目标 represents the target concentration of nitrate nitrogen after treatment; I represents the supply current; t represents the hydraulic retention time; M N represents the relative atomic mass of nitrogen; Step 2, enriching electroactive microorganisms and forming electroactive biofilms: Enriching electroactive microorganisms on the membrane carrier, the biochemical cotton in the middle layer promotes the adsorption of microorganisms by the membrane carrier, and forming electroactive biofilms on the stainless steel mesh; based on the detachable characteristics of the membrane carrier, this process can form electroactive biofilms in situ in the tube, or set up a culture pool to form the film ex situ and then move it into the tube; Step 3: introducing municipal tail water: opening the switchable water inlet hole and introducing the municipal tail water to be treated; turning on the diffusion device to allow the water in the pool to circulate in the pool in a specified direction; Step 4. Long-term stable treatment of municipal tail water: The electroactive biofilm dominated by electroactive microorganisms has the ability to directly metabolize electrons. The membrane carrier in the tube is powered by the cathode of the external circuit, which directly provides electrons for the denitrification reaction on the membrane carrier, and can efficiently remove nitrate nitrogen from the tail water. When the membrane carrier is damaged during long-term operation, it can be replaced with a membrane carrier that has formed an electroactive biofilm ectopically, which is convenient for equipment maintenance and beneficial to the long-term stable treatment of municipal tail water.

Images