Low carbon-nitrogen ratio sewage short path denitrification device and method thereof

Abstract

The application relates to a device for short-path denitrification of low-carbon-nitrogen-ratio sewage, which comprises an outer cylinder, wherein a middle cylinder and an inner cylinder are suspended in the outer cylinder, a short-path nitrification zone is arranged in the inner cylinder, a gas stripping zone is arranged above the inner cylinder and the middle cylinder, and a contact reduction zone is arranged below the inner cylinder and the middle cylinder, a sulfur autotrophic denitrification zone is arranged between the middle cylinder and the outer cylinder, and an oxygen supply system is arranged outside the outer cylinder and connected with the outer cylinder. The short-path nitrification, short-path denitrification, anaerobic ammonia oxidation, precipitation and sulfur autotrophic denitrification are integrated, the denitrification efficiency is high, the device is compact, and the land occupation is saved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sewage treatment, in particular to a short denitrification device for low carbon-nitrogen ratio sewage and a method thereof. BACKGROUND

[0002] Generally, sewage with COD / TN less than 5 is considered as a typical low-carbon source water, referred to as low C / N sewage. Such sewage comes from industrial production discharged wastewater, part of contaminated river water and groundwater, municipal secondary sewage plant effluent and nitrification sludge supernatant, etc.

[0003] Biological denitrification technology has always been the preferred technology route for treating ammonia-nitrogen wastewater, and is favored due to its stability and economy. With the continuous progress of biological technology and engineering technology, short-cut nitrification-denitrification and anaerobic ammonia oxidation, etc. efficient and economical biological denitrification technology has been deeply researched. Compared with traditional wastewater denitrification technology, short-cut nitrification-denitrification technology can theoretically save 25% of aeration energy consumption, reduce 40% of carbon source demand, and significantly improve the denitrification rate. Anaerobic ammonia oxidation technology can realize autotrophic denitrification under carbon-free conditions, and is an advanced biological denitrification technology. However, due to the difficulty in stable and efficient realization of ammonia-nitrogen nitrosation and anaerobic ammonia oxidation bacteria in practical application, the large-scale engineering application of short-cut nitrification-denitrification and anaerobic ammonia oxidation technology still faces major limitations.

[0004] For example, patent No. CN109292981B discloses a micro-nano bubble oxygen supply full-process denitrification reactor and a method thereof, which has the following defects: first, the oxygen supply in the aerobic section is provided by the micro-nano bubble generator, and no other technical means is adopted, so the short-cut nitrification reaction is unstable and easy to become full nitrification; second, the gas release section can only release small bubbles in water and cannot or can only release a small amount of dissolved oxygen, so the low dissolved oxygen environment in the anoxic section and the anaerobic section cannot be guaranteed due to the influence of the change of influent water quality and the nitrification strength in the aerobic section, and there is a risk of dissolved oxygen penetration, large dissolved oxygen fluctuation in the anoxic section and the anaerobic section, thereby destroying the short-cut denitrification and anaerobic ammonia oxidation reactions in the anoxic section and the anaerobic section, and the microbial reactions in each section are destroyed, which cannot achieve the expected effect; third, the separation zone is directly connected with the anoxic section of the reaction zone, and the mud and water in the separation zone are only separated by gravity sedimentation, which is easily affected by water quality, microbial activity, etc. to cause turbidity of the effluent.

[0005] As disclosed in Patent No. CN103508562B, an integrated swimming type self-circulation denitrification reactor has the following disadvantages: first, the reaction zone is directly supplied with oxygen by the bottom aeration head, the liquid phase in the reaction zone is quickly lifted and flushed against the hollow ball filler in the reaction zone, and it is difficult for the hollow ball filler surface to enrich microorganisms to form a biofilm, so it is difficult to create an internal anoxic or anaerobic environment for denitrifying bacteria and anaerobic ammonia oxidation bacteria; second, it is difficult to adjust the dissolved oxygen level in the liquid phase by simply adjusting the aeration flow, and the dissolved oxygen level is easily affected by factors such as fan condition, air temperature, humidity, etc.; third, the reflux pipe is refluxed from the top of the device to the same side of the bottom of the device through the connecting pipe, and this structure will cause part of the water flow to directly enter the separation zone during the lifting process, resulting in ammonia nitrogen and nitrite nitrogen escaping and the effluent exceeding the standard.

[0006] Therefore, in view of the above problems, the present application aims to improve the problems that the prior art is difficult to realize stable nitrosation and enrichment of anaerobic ammonia oxidation bacteria, and provides a device capable of stably realizing nitrosation and anaerobic ammonia oxidation. SUMMARY

[0007] The purpose of the present application is to provide a low carbon-nitrogen ratio sewage short-cut denitrification device and method.

[0008] The technical problem of the present application is mainly solved by the following technical scheme:

[0009] A low carbon-nitrogen ratio sewage short-cut denitrification device, comprising an outer cylinder, wherein a middle cylinder and an inner cylinder are suspended in the outer cylinder, and a short-cut nitrification zone is arranged in the inner cylinder, an air stripping zone is arranged above the inner cylinder and the middle cylinder, and a contact reduction zone is arranged below the inner cylinder and the middle cylinder, a sulfur autotrophic denitrification zone is arranged between the middle cylinder and the outer cylinder, and an oxygen supply system is further arranged outside the outer cylinder and connected thereto;

[0010] The short-cut nitrification zone comprises an aeration assembly, a water inlet pipe, an online pH meter and an online DO meter 1, wherein the aeration assembly comprises an aeration head arranged at the bottom of the inner cylinder and an air outlet pipe connected with the aeration head, and the water inlet pipe, the online pH meter and the online DO meter 1 are arranged at the top opening of the inner cylinder;

[0011] The air stripping zone is composed of a filler bed, an upper perforated plate and a lower perforated plate, and the upper perforated plate and the lower perforated plate are fixed between the inner cylinder and the middle cylinder;

[0012] The contact reduction zone is composed of hollow filler balls, polyurethane sponge fillers, a filler support and an online DO meter 2, the hollow filler balls are filled with the polyurethane sponge fillers, the hollow filler balls are connected in series by elastic ropes and fixed at both ends on the filler support, and the online DO meter 2 is installed above the contact reduction zone;

[0013] The sulfur autotrophic denitrification zone is composed of a filter layer, a supporting layer and an overflow weir, the filter layer is formed by mixing sulfur autotrophic denitrification filter material with carbonate-containing solid particles in a certain proportion, the sulfur autotrophic denitrification filter material is a solid particle loaded with sodium sulfide, sodium thiosulfate and elemental sulfur in a reduced state, the supporting layer is composed of a supporting plate and supporting layer filter material, the supporting plate is provided with uniformly distributed holes, and the supporting layer filter material is carbonate-containing solid particles, and the overflow weir is installed on the inner wall of the outer cylinder above the filter layer.

[0014] The oxygen supply system comprises a gas collecting hood arranged at the top end of the middle cylinder, wherein the gas collecting hood is connected with a lean oxygen air pipe provided with a lean oxygen air regulating valve, and the lean oxygen air pipe is connected with a rich oxygen air pipe provided with a rich oxygen air regulating valve through a circulating pipe provided with a circulating pipe regulating valve, and the rich oxygen air pipe is connected with a fan through an air inlet pipe, and the fan is connected with an air outlet pipe.

[0015] As a preferred solution, the rich oxygen air regulating valve is installed upstream of the connection between the rich oxygen air pipe and the circulating pipe, and the lean oxygen air regulating valve is installed upstream of the connection between the lean oxygen air pipe and the circulating pipe.

[0016] As a preferred solution, the inner cylinder and the middle cylinder are both connected by a straight cylinder segment at the upper part and a flared mouth at the lower part, wherein the angle of the lower flared mouth of the inner cylinder and the middle cylinder is 30°-60°, the distance between the bottom end of the flared mouth of the inner cylinder and the bottom of the outer cylinder is 1-5 cm, and the distance between the bottom end of the flared mouth of the middle cylinder and the bottom of the outer cylinder is 30-50 cm.

[0017] As a preferred solution, zeolite particles are added to the short-cut nitrification zone, wherein the volume of the zeolite particles accounts for 2%-20% of the volume of the nitrification functional zone, and the particle size of the zeolite particles is 40-100 mesh.

[0018] As a preferred solution, the hollow filler balls in the contact reduction zone are arranged radially in the horizontal direction.

[0019] As a preferred solution, the filler in the gas precipitation zone is one or more of Rasching ring, Pall ring, ladder ring, arc saddle, square saddle, metal ring square saddle, grid filler and corrugated filler.

[0020] A method for using a low-carbon-nitrogen-ratio sewage short-cut denitrification device, the treatment process is as follows:

[0021] Firstly, the fan blows air into the inner cylinder short-range nitrification zone, oxygen is dissolved in water and used by ammonia-oxidizing bacteria to carry out short-range nitrification reaction to convert ammonia nitrogen into nitrite nitrogen, under the action of airflow lifting, the sewage flows through the upper part of the inner cylinder and mixes with raw water in the water inlet pipe, and then enters the top gas separation zone in a radial manner, the sewage in the gas separation zone separates out oxygen and then enters the contact reduction zone, in the contact reduction zone, denitrifying bacteria on the surface of the hollow filler ball first use the carbon source in the sewage to carry out short-range denitrification to reduce the nitrate nitrogen produced in the anaerobic ammonia oxidation reaction in the previous cycle into nitrite nitrogen, then the nitrite nitrogen and ammonia nitrogen are directly reduced into nitrogen by the anaerobic ammonia oxidation bacteria in the hollow filler ball, thereby achieving the removal of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen, and the sewage flowing through the contact reduction zone is partially returned to the short-range nitrification zone from the horn at the bottom of the inner cylinder, and the other part flows to the sulfur autotrophic denitrification zone of the outer ring through the horn at the lower part of the middle cylinder, and the small amount of nitrate nitrogen produced in the anaerobic ammonia oxidation reaction is reduced into nitrogen, and finally discharged through the overflow weir above the sulfur autotrophic denitrification zone;

[0022] Wherein, zeolite particles are added in the short-range nitrification zone and are uniformly distributed in water under the action of air stripping, part of the zeolite particles are intercepted by the hollow filler ball and loaded on the filler during the circulation of the water flow through the contact reduction zone, the ammonia nitrogen adsorbed by the zeolite particles provides a part of ammonia nitrogen source for the anaerobic ammonia oxidation bacteria, and plays a role in stabilizing and buffering the ammonia nitrogen concentration.

[0023] Meanwhile, the DO of the on-line DO meter 1 is maintained in the range of 0.5-2.5 mg / L, when the DO of the on-line DO meter 2 is ≤0.3 mg / L, the opening degree of the adjusting valve of each air pipe remains unchanged, when the DO of the on-line DO meter 2 is >0.3 mg / L, the opening degree of the adjusting valve of the oxygen-poor air pipe is adjusted to be smaller, the opening degree of the adjusting valve of the circulation pipe is adjusted to be larger, and the opening degree of the adjusting valve of the oxygen-rich air pipe remains unchanged, so that part of the oxygen-poor air is circulated, the negative pressure in the gas collecting hood is increased, and more oxygen is separated out in the gas separation zone, thereby maintaining the DO of the on-line DO meter 2 below 0.3 mg / L.

[0024] The beneficial effects of the present application are as follows:

[0025] 1. In the present application, zeolite particles are added in the inner cylinder, ammonia nitrogen is adsorbed by the zeolite, and a high free ammonia environment is created on the surface of the zeolite at high pH, because ammonia-oxidizing bacteria (AOB) can tolerate higher free ammonia and pH than nitrite-oxidizing bacteria (NOB), NOB is gradually eliminated in the high free ammonia and high pH environment, so as to achieve the purpose of inhibiting the growth of NOB and enriching AOB, and realize short-range nitrification reaction; meanwhile, part of the zeolite particles are intercepted by the hollow filler ball, when the ammonia nitrogen concentration in the water flow is reduced, the zeolite particles release ammonia nitrogen, and when the ammonia nitrogen concentration in the water flow is increased, the zeolite particles adsorb ammonia nitrogen, thereby providing a stable ammonia nitrogen source for the anaerobic ammonia oxidation bacteria in the hollow filler ball.

[0026] 2. The short nitrification, short denitrification, anaerobic ammonia oxidation, precipitation, and sulfur autotrophic denitrification are integrated in one body, the nitrogen removal efficiency is high, the equipment is compact, and the land occupation is saved.

[0027] 3. The application optimizes the aeration structure design, adopts the structure of straight cylinder in the upper part and umbrella shape in the lower part, so that the zeolite particles and biological strains can realize oxygen supply demand and circulation lifting under the action of aeration lifting, microorganisms are more easily contacted with substrates, and a better survival environment is provided for the microorganisms.

[0028] 4. The application adjusts the oxygen supply amount by adjusting the lean oxygen air circulation amount and the vacuum degree above the aeration zone under the condition that the inhaled air amount remains unchanged, and realizes precise oxygen control.

[0029] 5. The application increases the sulfur autotrophic denitrification zone in the outermost circle, further reduces nitrate nitrogen in effluent, and the denitrification filter material can also filter suspended matter in the effluent, so that the effluent is stable and clear without suspended matter, and a sedimentation tank is not needed.

[0030] 6. The application is filled with fillers in the gas separation zone, has a large specific surface area, and has a large gas-liquid contact area on the surface of the filler, which is beneficial to the separation of oxygen under the action of negative pressure.

[0031] 7. The contact reduction zone is arranged in the reflux zone between the inner cylinder and the middle cylinder, the water flow is self-flowing from top to bottom by gravity, the effective strains on the surface and inside of the hollow filler ball are easy to adhere and grow and are not easy to be directly washed off by the water flow, the biological membrane is thick, and the anaerobic ammonia oxidation bacteria inside can be provided with a stable anoxic environment. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a structural schematic diagram of the application;

[0033] Figure 2 is a structural schematic diagram of the gas separation zone in the application.

[0034] In the figure: 1. outer cylinder, 2. sulfur autotrophic denitrification zone, 3. middle cylinder, 4. contact reduction zone, 5. inner cylinder, 6. gas outlet pipe, 7. fan, 8. oxygen-rich air pipe, 9. circulation pipe, 10. lean oxygen air pipe, 11. overflow weir, 12. online DO meter 2, 13. gas separation zone, 14. online DO meter 1, 15. gas collection hood, 16. online pH meter, 17. water inlet pipe, 61. aeration head, 71. air inlet pipe, 81. oxygen-rich air regulating valve, 91. circulation pipe regulating valve, 101. lean oxygen air regulating valve, 131. upper perforated plate, 132. lower perforated plate, 133. filler bed. DETAILED DESCRIPTION

[0035] The technical solutions of the present application are further specifically described below by way of examples in conjunction with the drawings.

[0036] The device for short-path denitrification of low carbon-nitrogen ratio sewage comprises an outer cylinder (1), wherein a middle cylinder (3) and an inner cylinder (5) are suspendedly arranged in the outer cylinder (1), a short-path nitrification zone (not shown) is arranged in the inner cylinder (5), a gas stripping zone (13) is arranged above the inner cylinder (5) and the middle cylinder (3), and a contact reduction zone (4) is arranged below the inner cylinder (5) and the middle cylinder (3), a sulfur autotrophic denitrification zone (2) is arranged between the middle cylinder (3) and the outer cylinder (1), and an oxygen supply system (not shown) is further arranged outside the outer cylinder (1) and connected with the outer cylinder (1);

[0037] The short-path nitrification zone comprises an aeration assembly, a water inlet pipe (17), an on-line pH meter (16) and an on-line DO meter 1 (14), wherein the aeration assembly comprises an aeration head (61) arranged at the bottom of the inner cylinder (5) and an air outlet pipe (6) connected with the aeration head (61), and the water inlet pipe (17), the on-line pH meter (16) and the on-line DO meter 1 (14) are all arranged at the top opening of the inner cylinder (5);

[0038] The gas stripping zone (13) is composed of a filler bed (133), an upper perforated plate (131) and a lower perforated plate (132), and the upper perforated plate (131) and the lower perforated plate (132) are fixed between the inner cylinder (5) and the middle cylinder (3);

[0039] The contact reduction zone (4) is composed of hollow filler balls, polyurethane sponge fillers, a filler support and an on-line DO meter 2 (12), the polyurethane sponge fillers are filled in the hollow filler balls, the hollow filler balls are connected in series by elastic ropes and fixed at both ends of the filler support, and the on-line DO meter 2 (12) is installed above the contact reduction zone (4);

[0040] The sulfur autotrophic denitrification zone (2) is composed of a filter layer, a supporting layer and an overflow weir (11), the filter layer is formed by mixing sulfur autotrophic denitrification filter material and carbonate-containing solid particles at a certain ratio, the sulfur autotrophic denitrification filter material is a solid particle loaded with sodium sulfide, sodium thiosulfate and elemental sulfur, the supporting layer is composed of a supporting plate and supporting layer filter material, the supporting plate is provided with uniformly distributed holes, the supporting layer filter material is carbonate-containing solid particles, and the overflow weir (11) is installed on the inner wall of the outer cylinder (1) above the filter layer;

[0041] The oxygen supply system comprises a gas collecting cover (15) arranged at the top end of the middle cylinder (3), wherein the gas collecting cover (15) is connected with a lean oxygen air pipe (10) in which a lean oxygen air regulating valve (101) is arranged, and the lean oxygen air pipe (10) is connected with an oxygen-rich air pipe (8) in which an oxygen-rich air regulating valve (81) is arranged through a circulation pipe (9) in which a circulation pipe regulating valve (91) is arranged, and the oxygen-rich air pipe (8) is connected with a fan (7) through an air inlet pipe (71), wherein the fan (7) is connected with an air outlet pipe (6).

[0042] As a preferred solution, the oxygen-rich air regulating valve (81) is arranged upstream of the connection between the oxygen-rich air pipe (8) and the circulation pipe (9), and the lean oxygen air regulating valve (101) is arranged upstream of the connection between the lean oxygen air pipe (10) and the circulation pipe (9).

[0043] As a preferred solution, the inner cylinder (5) and the middle cylinder (3) are both connected by a straight cylinder segment at the upper part and a trumpet mouth at the lower part, wherein the angle of the trumpet mouth of the inner cylinder (5) and the middle cylinder (3) is 30°-60°, the distance between the bottom end of the trumpet mouth of the inner cylinder (5) and the bottom of the outer cylinder (1) is 1-5 cm, and the distance between the bottom end of the trumpet mouth of the middle cylinder (3) and the bottom of the outer cylinder (1) is 30-50 cm.

[0044] As a preferred solution, zeolite particles are added to the short-cut nitrification zone, wherein the volume of the zeolite particles accounts for 2%-20% of the volume of the nitrification functional zone, and the particle size of the zeolite particles is 40-100 mesh.

[0045] As a preferred solution, the hollow filler balls in the contact reduction zone (4) are arranged radially in the horizontal direction.

[0046] As a preferred solution, the filler in the gas precipitation zone (13) is one or more of a Rasching ring, a Pall ring, a ladder ring, an arc saddle, a square saddle, a metal ring square saddle, a grid filler, and a corrugated filler.

[0047] A use method of a low carbon-nitrogen ratio sewage short-cut denitrification device, wherein the treatment process is as follows:

[0048] Firstly, the fan (7) blows air into the inner cylinder (5) to the short-range nitrification zone, oxygen dissolves in water and is used by ammonia-oxidizing bacteria to carry out short-range nitrification reaction to convert ammonia nitrogen into nitrite nitrogen, under the action of airflow lifting, the sewage flows through the upper part of the inner cylinder (5) and mixes with raw water in the water inlet pipe (17), and then enters the top gas separation zone (13) in a radial manner, the sewage in the gas separation zone (13) separates oxygen and then enters the contact reduction zone (4), the denitrifying bacteria on the surface of the hollow filler ball in the contact reduction zone (4) first use the carbon source in the sewage to carry out short-range denitrification to reduce the nitrate nitrogen produced in the anaerobic ammonia oxidation reaction in the previous cycle to nitrite nitrogen, and then the nitrite nitrogen and ammonia nitrogen are directly reduced to nitrogen by the anaerobic ammonia oxidation bacteria in the hollow filler ball, realizing the removal of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen, part of the sewage flowing through the contact reduction zone (4) flows back to the short-range nitrification zone from the trumpet at the bottom of the inner cylinder (5), and the other part flows to the sulfur autotrophic denitrification zone (2) of the outer ring through the trumpet at the lower part of the middle cylinder (3), and the small amount of nitrate nitrogen produced in the anaerobic ammonia oxidation reaction is reduced to nitrogen, and finally discharged through the overflow weir (11) above the sulfur autotrophic denitrification zone;

[0049] Wherein, zeolite particles are added in the short-range nitrification zone, which are uniformly distributed in water under the action of air stripping, and part of the zeolite particles are intercepted by the hollow filler ball and loaded on the filler during the circulation of the water flow through the contact reduction zone (4), the ammonia nitrogen adsorbed by the zeolite particles provides a part of the ammonia nitrogen source for the anaerobic ammonia oxidation bacteria, and plays a role in stabilizing and buffering the ammonia nitrogen concentration;

[0050] At the same time, the DO of the on-line DO meter 1 is maintained in the range of 0.5-2.5 mg / L, when the DO of the on-line DO meter 2 is ≤0.3 mg / L, the opening degree of the regulating valve of each air pipe remains unchanged, when the DO of the on-line DO meter 2 is >0.3 mg / L, the opening degree of the regulating valve of the oxygen-poor air pipe is adjusted to be smaller, the opening degree of the regulating valve of the circulation pipe is adjusted to be larger, and the opening degree of the regulating valve of the oxygen-rich air pipe remains unchanged, so that part of the oxygen-poor air circulates, the negative pressure in the gas collection hood increases, and more oxygen is separated in the gas separation zone, so that the DO of the on-line DO meter 2 is maintained below 0.3 mg / L.

[0051] As Figure 1As shown, low carbon-nitrogen ratio sewage enters the inner cylinder (5) through the inlet pipe (17), the fan (7) sends air into the bottom of the inner cylinder (5) through the fan outlet pipe (6) and the aeration head (61), and under the lifting effect of aeration, the water in the inner cylinder (5) flows upward. A certain proportion of zeolite particles is added in the inner cylinder, ammonia nitrogen is adsorbed by the zeolite, and a high free ammonia environment is created on the surface of the zeolite at high pH. Since ammonia-oxidizing bacteria (AOB) can tolerate higher free ammonia and pH than nitrite-oxidizing bacteria (NOB), NOB is gradually eliminated in the high free ammonia and high pH environment, achieving the purpose of inhibiting the growth of NOB and enriching AOB. The ammonia-oxidizing bacteria AOB in the inner cylinder (5) oxidize part of the ammonia nitrogen in the water into nitrous nitrogen using the dissolved oxygen in the water, realizing short-cut nitrification. The water and zeolite particles in the inner cylinder (5) rise from the bottom to the top and then flow radially to the gas stripping zone (13) above the middle cylinder (3) after mixing with the inlet water. When the water flows through the filler bed (133) in the gas stripping zone (13), a large gas-liquid contact surface is formed. The gas collector (15) above the gas stripping zone (13) is connected to the oxygen-poor air pipe (10), and the oxygen-poor air pipe (10) is in communication with the oxygen-rich air pipe (8) through the circulation pipe (9). Under the suction of the fan (7), a negative pressure is formed in the gas collector (15), breaking the dissolution equilibrium between the gas and liquid phases, allowing excess dissolved oxygen in the liquid phase to be stripped and recycled back to the fan inlet pipe (71) through the gas collector and the corresponding air pipe.

[0052] First, maintain the DO of the online DO meter 1 (14) in the range of 0.5-2.5 mg / L. When the DO of the online DO meter 2 (12) is ≤0.3 mg / L, the opening degree of the regulating valve of each air pipe remains unchanged. When the DO of the online DO meter 2 (12) is >0.3 mg / L, the opening degree of the oxygen-poor air pipe regulating valve (101) is adjusted smaller, the opening degree of the circulation pipe regulating valve (91) is adjusted larger, and the opening degree of the oxygen-rich air pipe regulating valve (81) remains unchanged, so that part of the oxygen-poor air is circulated, the negative pressure in the gas collector (15) is increased, and more dissolved oxygen is stripped in the gas stripping zone (13), thereby maintaining the DO of the online DO meter 2 (12) below 0.3 mg / L.

[0053] After the sewage passes through the gas stripping zone (13), the dissolved oxygen in the water is lower than 0.3 mg / L. At this time, the denitrifying bacteria on the surface of the hollow filler balls in the contact reduction zone (4) utilize the carbon source in the sewage for short-cut denitrification, reducing the nitrate nitrogen produced in the anaerobic ammonia oxidation reaction in the previous cycle to nitrite nitrogen. The anaerobic ammonia oxidation bacteria in the hollow filler balls utilize the ammonia nitrogen and nitrite nitrogen in the water to directly reduce them to nitrogen gas, achieving total nitrogen removal.

[0054] Meanwhile, part of the zeolite particles are intercepted by the hollow filler balls in the circulation process. When the ammonia nitrogen concentration in the water flow decreases, the zeolite particles release ammonia nitrogen; when the ammonia nitrogen concentration in the water flow increases, the zeolite particles adsorb ammonia nitrogen, thereby providing a stable ammonia nitrogen source for the anaerobic ammonia oxidation bacteria in the hollow filler balls.

[0055] Since the anaerobic ammonia oxidation reaction produces a small amount of nitrate nitrogen, part of the nitrate nitrogen in the effluent of the contact reduction zone (4) reenters the next cycle from the trumpet at the bottom of the inner cylinder (5), and the other part of the nitrate nitrogen enters the sulfur autotrophic denitrification zone (2) in the outer cylinder (1) from the trumpet at the bottom of the middle cylinder (3). The suspended solids in the water are intercepted by the filter material, and the remaining nitrate nitrogen in the water is reduced to nitrogen gas by the sulfur autotrophic denitrification bacteria, thereby achieving further removal of total nitrogen in the effluent. The treated water is discharged through the overflow weir (11) above the sulfur autotrophic denitrification zone (2).

[0056] The above has carried out the detailed explanation to the present application, but the content described is only the preferred embodiment of the present application, cannot be considered for limiting the implementation scope of the present application. All equivalent changes and improvements made according to the application scope of the present application should still belong to the patent coverage scope of the present application.

Claims

1. A short-cut nitrogen removal device for wastewater with a low carbon-to-nitrogen ratio, characterized in that: It includes an outer cylinder, in which a middle cylinder and an inner cylinder are suspended, and a short-cut nitrification zone is provided in the inner cylinder. Between the inner cylinder and the middle cylinder, there is a gas evolution zone located above and a contact reduction zone located below. Between the middle cylinder and the outer cylinder, there is a sulfur autotrophic denitrification zone. An oxygen supply system connected to the outer cylinder is also provided on the outside of the outer cylinder. The short-range nitrification zone includes an aeration assembly, an inlet pipe, an online pH meter, and an online DO meter 1. The aeration assembly includes an aeration head located at the bottom of the inner cylinder and an outlet pipe connected to the aeration head. The inlet pipe, the online pH meter, and the online DO meter 1 are all located at the top opening of the inner cylinder. The gas separation zone consists of a packing bed, an upper orifice plate, and a lower orifice plate, which are fixed between the inner cylinder and the middle cylinder. The contact reduction zone consists of hollow packing balls, polyurethane sponge packing, a packing support, and an online DO meter 2. The hollow packing balls are filled with the polyurethane sponge packing. The hollow packing balls are connected in series by elastic ropes and both ends are fixed on the packing support. The online DO meter 2 is installed above the contact reduction zone. The sulfur autotrophic denitrification zone consists of a filter media layer, a support layer, and an overflow weir. The filter media layer is composed of a mixture of sulfur autotrophic denitrification filter media and carbonate-containing solid particles. The sulfur autotrophic denitrification filter media consists of solid particles carrying sodium sulfide and sodium thiosulfate as a reduced sulfur source. The support layer consists of a support plate and support layer filter media. The support plate has uniformly distributed holes, and the support layer filter media consists of carbonate-containing solid particles. The overflow weir is installed on the inner wall of the outer cylinder above the filter media layer. The oxygen supply system includes a gas collection hood installed at the top of the middle cylinder, wherein the gas collection hood is connected to an oxygen-deficient air pipe equipped with an oxygen-deficient air regulating valve, and the oxygen-deficient air pipe is connected to an oxygen-enriched air pipe equipped with an oxygen-enriched air regulating valve through a circulation pipe. The circulation pipe is equipped with a circulation pipe regulating valve, and the oxygen-enriched air pipe is connected to a fan through an air inlet pipe, wherein the fan is connected to an air outlet pipe.

2. The low C / N ratio wastewater short-cut denitrification device according to claim 1, characterized in that: The oxygen-enriched air regulating valve is installed upstream of the connection between the oxygen-enriched air pipe and the circulation pipe, and the oxygen-deficient air regulating valve is installed upstream of the connection between the oxygen-deficient air pipe and the circulation pipe.

3. The low C / N ratio wastewater short-cut denitrification device according to claim 1, characterized in that: Both the inner cylinder and the middle cylinder are formed by connecting a straight upper section and a flared lower section. The flared lower section angle of both the inner cylinder and the middle cylinder is 30° to 60°. The distance between the bottom of the flared lower section of the inner cylinder and the bottom of the outer cylinder is 1 to 5 cm, and the distance between the bottom of the flared lower section of the middle cylinder and the bottom of the outer cylinder is 30 to 50 cm.

4. The low C / N ratio wastewater short-cut denitrification device according to claim 1, characterized in that: Zeolite particles were added to the short-range nitration zone, wherein the volume of the zeolite particles accounted for 2% to 20% of the volume of the nitration zone, and the particle size of the zeolite particles was 40 to 100 mesh.

5. A short-cut denitrification device for low C / N ratio wastewater according to claim 1, characterized in that: The hollow filler balls in the contact reduction zone are arranged radially in the horizontal direction.

6. The low C / N ratio wastewater short-cut denitrification device according to claim 1, characterized in that: The packing material in the gas separation zone is one or more of Raschig rings, Pall rings, stepped rings, arc saddles, rectangular saddles, metal ring rectangular saddles, grid packing, and corrugated packing.

7. A method for using a short-cut denitrification device for low carbon-to-nitrogen ratio wastewater, the treatment process of which is as follows: First, air is blown into the short-cut nitrification zone of the inner cylinder by a blower. Oxygen dissolves in the water and is utilized by ammonia-oxidizing bacteria to convert ammonia nitrogen into nitrite nitrogen through a short-cut nitrification reaction. Under the lifting effect of the airflow, the wastewater flows through the upper part of the inner cylinder and mixes with the raw water in the inlet pipe before entering the top gas separation zone in a radial pattern. After oxygen is released in the gas separation zone, the wastewater enters the contact reduction zone. In the contact reduction zone, denitrifying bacteria on the surface of the hollow packing balls first utilize the carbon source in the wastewater to perform short-cut denitrification, thus reversing the anaerobic ammonia oxidation reaction from the previous cycle. The generated nitrate nitrogen is reduced to nitrite nitrogen. Then, nitrite nitrogen and ammonia nitrogen are directly reduced to nitrogen gas by anaerobic ammonia oxidation bacteria inside the hollow packing ball, thus achieving the removal of ammonia nitrogen, nitrite nitrogen and nitrate nitrogen. After passing through the contact reduction zone, part of the wastewater flows back to the short-cut nitrification zone from the bell mouth at the bottom of the inner cylinder, and the other part flows to the sulfur autotrophic denitrification zone in the outer ring through the bell mouth at the bottom of the middle cylinder, where the small amount of nitrate nitrogen produced by the anaerobic ammonia oxidation reaction is reduced to nitrogen gas. Finally, it is discharged through the overflow weir above the sulfur autotrophic denitrification zone. Zeolite particles are added in the short-cut nitrification zone and are evenly distributed in the water under the action of air lifting. Some of the zeolite particles are intercepted by the hollow packing balls and loaded on the packing during the water circulation through the contact reduction zone. The ammonia nitrogen adsorbed by the zeolite particles provides a part of the ammonia nitrogen source for anaerobic ammonia oxidizing bacteria, and plays a role in stabilizing the ammonia nitrogen concentration. Meanwhile, the DO of online DO meter 1 is maintained within the range of 0.5 to 2.5 mg / L. When the DO of online DO meter 2 is ≤ 0.3 mg / L, the opening of the regulating valves of each air pipeline remains unchanged. When the DO of online DO meter 2 is > 0.3 mg / L, the opening of the regulating valve of the oxygen-deficient air pipeline is reduced, the opening of the regulating valve of the circulation pipeline is increased, and the opening of the regulating valve of the oxygen-enriched air pipeline remains unchanged. This causes some oxygen-deficient air to circulate and the negative pressure in the gas collection hood to increase, thereby causing more oxygen to be released in the gas evolution zone and maintaining the DO of online DO meter 2 below 0.3 mg / L.

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