CN117164114A - System and method for cooperatively strengthening low C/N ratio sewage denitrification by utilizing sulfur autotrophic denitrification - Google Patents

Abstract

The invention discloses a system and a method for cooperatively strengthening low C/N ratio sewage denitrification by utilizing sulfur autotrophic denitrification, wherein a water inlet pipeline is communicated with an inlet of an anaerobic tank, an outlet of the anaerobic tank is communicated with an inlet of an anoxic tank, the outlet of the anoxic tank is divided into two paths, one path is communicated with an inlet of an autotrophic denitrification tank/reactor, the other path is communicated with an inlet of an aerobic tank, an outlet of the autotrophic denitrification tank/reactor is communicated with the inlet of the aerobic tank and the inlet of the autotrophic denitrification tank/reactor, an outlet of the aerobic tank is communicated with an inlet of a sedimentation tank and an inlet of the anoxic tank, a water outlet of the sedimentation tank is communicated with a water outlet pipeline, and a bottom sludge outlet of the sedimentation tank is divided into two paths, wherein the other path is communicated with a sludge discharge pipeline, and the other path is communicated with the inlet of the anaerobic tank.

Description

A system that utilizes sulfur autotrophic denitrification to synergistically enhance the denitrification of low C/N ratio sewage and method

Technical field

The invention belongs to the biotechnology field of sewage treatment, and relates to a system and method for utilizing sulfur autotrophic denitrification to synergistically strengthen the denitrification of low C/N ratio sewage.

Background technique

In the process of urban domestic sewage treatment, heterotrophic denitrification using organic matter as electron donor plays a key role in the removal of nitrogen pollution in wastewater. In the process of heterotrophic denitrification and denitrification, denitrifying bacteria need to consume organic matter in wastewater as electron donors to achieve the conversion of nitrate nitrogen/nitrite nitrogen to nitrogen under anaerobic or anoxic conditions. At present, a variety of mature processes have been developed based on the principle of heterotrophic denitrification and denitrification and have been widely used, including A ² /O, SBR, MBR, oxidation ditch, etc. However, in actual wastewater treatment, insufficient carbon sources and nitrification problems are common. Problems such as liquid reflux restriction lead to poor denitrification efficiency and substandard effluent. It is generally believed that a C/N ratio in wastewater exceeding 5 can ensure better biological activity of heterotrophic denitrifying bacteria and achieve a relatively high denitrification effect in the denitrification process. When the C/N ratio in wastewater is too low, the heterotrophic denitrification process lacks sufficient electron donors, and external carbon sources must be supplemented to ensure the denitrification effect of the heterotrophic denitrification process. However, adding external carbon sources not only increases the cost of sewage treatment, but also increases the remaining sludge production and may lead to secondary pollution (effluent COD exceeds the standard). There are common problems such as poor effect and difficulty in control, that is, there is low C/N ratio sewage Commonly faced problems include incomplete denitrification during the denitrification stage, total nitrogen exceeding the standard, and the addition of external carbon sources leading to an increase in remaining sludge and effluent COD easily exceeding the standard.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a system and method for utilizing sulfur autotrophic denitrification to synergistically strengthen the denitrification of low C/N ratio sewage. The remaining sludge and the possible risk of COD exceeding the standard.

In order to achieve the above objectives, the present invention discloses a system that utilizes sulfur autotrophic denitrification to synergistically strengthen the denitrification of low C/N ratio sewage, including a sludge discharge pipe, a water inlet pipe, an anaerobic pool, an anoxic pool, an autotrophic pool, and an anaerobic pool. Denitrification tank/reactor, aerobic tank and sedimentation tank;

The water inlet pipe is connected to the entrance of the anaerobic tank, and the outlet of the anaerobic tank is connected to the entrance of the anoxic tank. The outlet of the anoxic tank is divided into two channels, one of which is connected to the entrance of the autotrophic denitrification tank/reactor. The other road is connected to the entrance of the aerobic tank, the outlet of the autotrophic denitrification tank/reactor is connected to the entrance of the aerobic tank and the entrance of the autotrophic denitrification tank/reactor, and the outlet of the aerobic tank is connected to the sedimentation tank. The entrance of the tank is connected to the entrance of the anoxic tank, and the water outlet of the sedimentation tank is connected to the water outlet pipe. The sludge outlet at the bottom of the sedimentation tank is divided into two ways, one of which is connected to the sludge discharge pipe, and the other is connected to the anaerobic The entrance to the pool is connected.

The outlet of the anoxic tank is divided into two channels, one of which is connected to the inlet of the autotrophic denitrification tank/reactor via the autotrophic denitrification pump, and the other is connected to the inlet of the aerobic tank via the heterotrophic denitrification pump.

The bottom sludge outlet of the sedimentation tank is connected to the inlet of the anaerobic tank through a sludge pump.

The outlet of the aerobic tank is connected to the inlet of the anoxic tank through the nitrification liquid reflux pump.

The outlet of the autotrophic denitrification tank/reactor is connected to the inlet of the autotrophic denitrification tank/reactor through an autotrophic pump.

It also includes aeration equipment, wherein the aeration equipment is connected with the aerobic tank.

The method of utilizing sulfur autotrophic denitrification to synergistically strengthen the denitrification of low C/N ratio sewage according to the present invention includes the following steps:

1) The sewage output from the anaerobic tank merges with the partially refluxed nitrification liquid output from the aerobic tank and enters the anoxic tank. In the anoxic tank, heterotrophic denitrifying bacteria use organic matter in the water as electron donors to carry out low C/ The denitrification reaction of N ratio sewage reduces part of the nitrate nitrogen in the sewage to nitrogen gas;

2) Divide the water output from the anoxic pool containing nitrate nitrogen into two channels, one of which enters the aerobic pool for excessive phosphorus absorption by phosphorus-accumulating bacteria, degradation of residual organic matter, and oxidation of organic nitrogen and ammonia nitrogen; the other channel enters the autotrophic The autotrophic denitrification reaction continues in the denitrification tank/reactor. In the autotrophic denitrification tank/reactor, autotrophic denitrifying bacteria are used to perform the denitrification reaction, and elemental sulfur particles are added as autotrophic denitrifying bacteria. Electron donor, relying on hydraulic scouring to accelerate the dissolution of elemental sulfur particles;

3) The supernatant output from the autotrophic denitrification tank/reactor is divided into two routes, one of which returns to the entrance of the autotrophic denitrification tank/reactor, and the other route enters the aerobic tank;

4) In the aerobic tank, the organic nitrogen and ammonia nitrogen in the sewage are oxidized into nitrate nitrogen. The water output from the aerobic tank is divided into two channels, one of which enters the anoxic tank as the reflux digestive liquid, and the other enters the sedimentation The mud and water are separated in the tank, and the sludge at the bottom of the sedimentation tank is divided into two routes, one of which is used as activated sludge and returned to the anaerobic tank, and the other is used as residual sludge for external discharge treatment.

The ratio of the amount of water output from the anaerobic tank to the anoxic tank and the amount of nitrification liquid returned from the aerobic tank to the anoxic tank is 1:2 to 4.

In the effluent of the anoxic tank, the amount of water entering the autotrophic denitrification tank/reactor accounts for 70%-90% of the total effluent of the anoxic tank.

The average particle size of elemental sulfur particles is 1.0-2.0mm.

The invention has the following beneficial effects:

During specific operation, the system and method for utilizing sulfur autotrophic denitrification to synergistically strengthen the denitrification of low C/N ratio sewage according to the present invention constructs an autotrophic denitrification tank/reactor on the heterotrophic denitrification water outlet path. The autotrophic denitrification and denitrification unit uses sulfur autotrophic denitrification to achieve the removal of residual nitrate nitrogen in low C/N ratio sewage during the heterotrophic denitrification process, effectively solving the problem of conventional processes facing low C/N ratio sewage in low carbon The problem of poor denitrification effect under low C /N ratio stability and flexibility of the system under fluctuations in sewage water quality. At the same time, it should be noted that the autotrophic denitrification tank/reactor can be directly set up as a bypass of the sewage treatment system and has no special requirements for the installation environment. It does not require significant modifications to the original sewage treatment system, and is easy to implement and control the project, reducing investment in engineering modifications. smaller.

Description of drawings

Figure 1 is a system structure diagram of the present invention.

Among them, 1 is an anaerobic tank, 2 is an anoxic tank, 2-1 is a heterotrophic denitrification pump, 2-2 is an autotrophic denitrification pump, 3 is an autotrophic denitrification tank/reactor, and 3-1 is an autotrophic denitrification tank. Nutrient pump, 4 is the aerobic tank, 4-1 is the nitrification liquid return pump, 5 is the sedimentation tank, and 5-1 is the sludge pump.

Detailed ways

In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only These are part of the embodiments of the present invention, not all of them, and are not intended to limit the scope of the disclosure of the present invention. Furthermore, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall within the scope of protection of the present invention.

A schematic structural diagram according to a disclosed embodiment of the present invention is shown in the accompanying drawings. The drawings are not drawn to scale, with certain details exaggerated and may have been omitted for purposes of clarity. The shapes of the various regions and layers shown in the figures and the relative sizes and positional relationships between them are only exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art will base their judgment on actual situations. Additional regions/layers with different shapes, sizes, and relative positions can be designed as needed.

Referring to Figure 1, the system of the present invention that uses sulfur autotrophic denitrification to synergistically enhance the denitrification of low C/N ratio sewage includes an anaerobic tank 1, an anoxic tank 2, an autotrophic denitrification tank/reactor 3, and an aerobic tank. Tank 4 and sedimentation tank 5;

The water inlet pipe is connected to the inlet of anaerobic pool 1, and the outlet of anaerobic pool 1 is connected to the inlet of anoxic pool 2. The outlet of anoxic pool 2 is divided into two paths, one of which passes through the autotrophic denitrification pump 2- 2 is connected to the inlet of the autotrophic denitrification tank/reactor 3, the other is connected to the inlet of the aerobic tank 4 through the heterotrophic denitrification pump 2-1, and the outlet of the autotrophic denitrification tank/reactor 3 is connected to the inlet of the aerobic tank 4. The inlet of the oxygen tank 4 is connected, the outlet of the aerobic tank 4 is connected with the entrance of the sedimentation tank 5, the water outlet of the sedimentation tank 5 is connected with the water outlet pipe, the bottom sludge outlet of the sedimentation tank 5 is divided into two channels, one of which is It is connected with the sludge discharge pipe, and the other channel is connected with the inlet of the anaerobic tank 1 through the sludge pump 5-1.

In this embodiment, the outlet of the aerobic pool 4 is connected to the inlet of the anoxic pool 2 through the nitrification liquid reflux pump 4-1.

In this embodiment, the outlet of the autotrophic denitrification tank/reactor 3 is connected to the inlet of the autotrophic denitrification tank/reactor 3 via the autotrophic pump 3-1.

In this embodiment, aeration equipment is also included, wherein the aeration equipment is connected with the aerobic tank 4 .

In the anoxic tank 2, heterotrophic denitrifying bacteria consume the organic matter flowing into the anaerobic tank 1 as an electron donor, and reduce the nitrate brought back by the nitrification liquid return pump 4-1 into nitrogen through heterotrophic denitrification, and then Escape into the atmosphere to achieve the removal of organic carbon and nitrates in wastewater. The water output from the anoxic tank 2 carries residual nitrate and enters the autotrophic denitrification tank/reactor 3 through the autotrophic denitrification pump 2-2; in the autotrophic denitrification tank/reactor 3, the autotrophic denitrifying bacteria The added elemental sulfur is an electron donor, and through autotrophic denitrification, the remaining nitrate inflow is reduced to nitrogen and escapes into the atmosphere, achieving deep removal of nitrate in wastewater. The autotrophic denitrification tank/reactor 3 is connected to the aerobic tank 4 through a pipeline, and performs a reflux cycle through an autotrophic pump 3-1 to improve the mixing effect, promote the dissolution of elemental sulfur particles, and replenish the lost autotrophic Denitrification sludge improves the stability and treatment efficiency of the autotrophic denitrification tank/reactor 3; in the aerobic tank 4, the aerobic environment in the aerobic tank 4 is maintained through aeration equipment, and nitrifying bacteria pass through aerobic organisms Nitrification converts ammonia nitrogen and organic nitrogen into nitrate nitrogen, wherein part of the effluent from the aerobic pool 4 flows back to the anoxic pool 2 through the nitrification liquid return pump 4-1 to supplement the anoxic pool 2 with sufficient nitrate; Part of the sludge deposited at the bottom of the sedimentation tank 5 is returned to the anaerobic tank 1 through the sludge pump 5-1, and the remaining sludge is discharged for disposal.

The method of utilizing sulfur autotrophic denitrification to synergistically strengthen the denitrification of low C/N ratio sewage according to the present invention includes the following steps:

1) The sewage output from the anaerobic pool 1 and the partially recovered nitrification liquid output from the aerobic pool 4 are uniformly combined and then enter the anoxic pool 2. In the anoxic pool 2, the heterotrophic denitrifying bacteria use the organic matter in the water to provide electrons. The body carries out denitrification reaction of low C/N ratio sewage, reducing part of the nitrate nitrogen in the sewage into nitrogen gas;

2) Divide the water output from the anoxic pool 2 containing nitrate nitrogen into two channels, one of which enters the aerobic pool 4 for excessive phosphorus absorption by phosphorus-accumulating bacteria, degradation of residual organic matter, and oxidation of organic nitrogen and ammonia nitrogen; the other part enters The autotrophic denitrification reaction continues in the autotrophic denitrification tank/reactor 3. In the autotrophic denitrification tank/reactor 3, autotrophic denitrifying bacteria are used to perform the denitrification reaction, and elemental sulfur particles are added as an autotrophic denitrification reaction. The electron donor that supports denitrifying bacteria is placed close to the water inlet of the autotrophic denitrification tank/reactor 3 and relies on hydraulic flushing to accelerate the dissolution of elemental sulfur particles;

3) The supernatant output from the autotrophic denitrification tank/reactor 3 is divided into two routes, one of which returns to the entrance of the autotrophic denitrification tank/reactor 3, and the other route enters the aerobic tank 4;

4) In the aerobic pool 4, the organic nitrogen and ammonia nitrogen in the sewage are oxidized into nitrate nitrogen. The water output from the aerobic pool 4 is divided into two channels, one of which enters the anoxic pool 2 as the return digestion liquid, and the other All the way enters the sedimentation tank 5 for mud-water separation. The sludge at the bottom of the sedimentation tank 5 is divided into two routes, one of which is returned to the anaerobic tank 1 as activated sludge, and the other is used as residual sludge for discharge treatment.

In this embodiment, the COD/TN in the low C/N ratio sewage is ≤5.0; the water enters the anoxic pool 2, where the water output from the anaerobic pool 1 to the anoxic pool 2 and the aerobic pool 4 return to The flow ratio of the nitrification solution in the anoxic tank 2 is 1:2~4.

In this embodiment, the BOD in the effluent of the anoxic tank 2 is ≤ 30 mg/L; in the effluent of the anoxic tank 2, the amount of water entering the autotrophic denitrification tank/reactor 3 accounts for 70%-90% of the total effluent of the anoxic tank 2. %, the dissolved oxygen concentration of wastewater is ≤0.5mg/L, and the pH is between 7.0-8.5.

In this embodiment, the average particle size of the elemental sulfur particles is 1.0-2.0 mm; the added elemental sulfur particles need to satisfy the sulfur-nitrogen mass ratio between the dissolved elemental sulfur and nitrate per unit time of 2.5-4.5.

In this embodiment, the controlled hydraulic retention time of the autotrophic denitrification tank/reactor 3 is 0.5-4.0h, the dissolved oxygen concentration is ≤0.5mg/L, and the pH is between 7.0-8.0.

In this embodiment, the control range of the reflux ratio of the effluent from the autotrophic denitrification tank/reactor 3 is 400%-500%.

The invention has the following characteristics:

The present invention couples an autotrophic denitrification tank/reactor 3 between an anoxic tank 2 and an aerobic tank 4, uses sulfur autotrophic denitrification to compensate for the removal of remaining nitrates in the effluent of the anoxic tank 2, and effectively strengthens the process for low C /N ratio sewage denitrification effect, reducing its requirements for the incoming water C/N ratio; at the same time, the autotrophic denitrification tank/reactor 3 can be flexibly set up in the bypass of the sewage treatment system, with no special requirements for the installation environment, and is easy to Project implementation.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that the present invention can still be modified. Modifications or equivalent substitutions may be made to the specific embodiments, and any modifications or equivalent substitutions that do not depart from the spirit and scope of the invention shall be covered by the scope of the claims of the invention.

Claims (10)

1. A system that uses sulfur autotrophic denitrification to synergistically strengthen the denitrification of low C/N ratio sewage, which is characterized by including a sludge discharge pipe, a water inlet pipe, an anaerobic tank (1), and an anoxic tank (2) , autotrophic denitrification tank/reactor (3), aerobic tank (4) and sedimentation tank (5); The water inlet pipe is connected to the entrance of the anaerobic tank (1), and the outlet of the anaerobic tank 1 is connected to the entrance of the anoxic tank (2). The outlet of the anoxic tank (2) is divided into two paths, one of which is connected to the natural gas tank. The inlet of the autotrophic denitrification tank/reactor (3) is connected, the other is connected with the inlet of the aerobic tank (4), and the outlet of the autotrophic denitrification tank/reactor (3) is connected with the inlet of the aerobic tank (4). The entrance is connected to the entrance of the autotrophic denitrification tank/reactor (3), the outlet of the aerobic tank (4) is connected to the entrance of the sedimentation tank (5) and the entrance of the anoxic tank (2), and the sedimentation tank (5) ) is connected to the water outlet pipe, and the bottom sludge outlet of the sedimentation tank (5) is divided into two ways, one of which is connected to the sludge discharge pipe, and the other is connected to the inlet of the anaerobic tank (1). 2. A system for utilizing sulfur autotrophic denitrification to synergistically strengthen low C/N ratio sewage denitrification according to claim 1, characterized in that the outlet of the anoxic tank (2) is divided into two channels, one of which is autotrophic. The denitrification pump (2-2) is connected to the inlet of the autotrophic denitrification tank/reactor (3), and the other path is connected to the inlet of the aerobic tank (4) through the heterotrophic denitrification pump (2-1). 3. The system of utilizing sulfur autotrophic denitrification to synergistically strengthen low C/N ratio sewage denitrification according to claim 1, characterized in that the bottom sludge outlet of the sedimentation tank (5) passes through the sludge pump (5-1 ) is connected with the entrance of the anaerobic tank (1). 4. The system for utilizing sulfur autotrophic denitrification to synergistically strengthen low C/N ratio sewage denitrification according to claim 1, characterized in that the outlet of the aerobic pool (4) passes through the nitrification liquid reflux pump (4-1) It is connected with the entrance of the anoxic pool (2). 5. A system for utilizing sulfur autotrophic denitrification to synergistically strengthen low C/N ratio sewage denitrification according to claim 1, characterized in that the outlet of the autotrophic denitrification tank/reactor (3) passes through an autotrophic pump ( 3-1) is connected to the inlet of the autotrophic denitrification tank/reactor (3). 6. The system of utilizing sulfur autotrophic denitrification to synergistically strengthen the denitrification of low C/N ratio sewage according to claim 1, characterized in that it also includes aeration equipment, wherein the aeration equipment and the aerobic tank (4) Connected. 7. A method for utilizing sulfur autotrophic denitrification to synergistically enhance the denitrification of low C/N ratio sewage, which is characterized by including the following steps: 1) The sewage output from the anaerobic tank (1) merges with the partially returned nitrification liquid output from the aerobic tank (4) and enters the anoxic tank (2). In the anoxic tank (2), heterotrophic denitrifying bacteria Use organic matter in the water as electron donor to carry out denitrification reaction of low C/N ratio sewage, and reduce part of the nitrate nitrogen in the sewage to nitrogen gas; 2) Divide the water output from the anoxic pool (2) containing nitrate nitrogen into two channels, one of which enters the aerobic pool (4) for excessive phosphorus absorption by phosphorus-accumulating bacteria, degradation of residual organic matter, and oxidation of organic nitrogen and ammonia nitrogen. ; The other path enters the autotrophic denitrification tank/reactor (3) to continue the autotrophic denitrification reaction. In the autotrophic denitrification tank/reactor (3), autotrophic denitrifying bacteria are used to perform the denitrification reaction. At the same time, elemental sulfur particles are added as electron donors for autotrophic denitrifying bacteria, and hydraulic flushing is used to accelerate the dissolution of elemental sulfur particles; 3) The supernatant output from the autotrophic denitrification tank/reactor (3) is divided into two routes, one of which returns to the entrance of the autotrophic denitrification tank/reactor (3), and the other route enters the aerobic tank ( 4) medium; 4) In the aerobic tank (4), the organic nitrogen and ammonia nitrogen in the sewage are oxidized into nitrate nitrogen. The water output from the aerobic tank (4) is divided into two channels, one of which enters the anoxic tank as the reflux digestive juice. (2), the other channel enters the sedimentation tank (5) for mud-water separation. The sludge at the bottom of the sedimentation tank (5) is divided into two channels, one of which is used as activated sludge and returns to the anaerobic tank (1), and the other is used as activated sludge to return to the anaerobic tank (1). The remaining sludge will be discharged for treatment. 8. The method of utilizing sulfur autotrophic denitrification to synergistically strengthen the denitrification of low C/N ratio sewage according to claim 7, characterized in that the amount of water output from the anaerobic tank (1) to the anoxic tank (2) is equal to The ratio of the amount of nitrification liquid returned from the aerobic pool (4) to the anoxic pool (2) is 1:2-4. 9. The method of utilizing sulfur autotrophic denitrification to synergistically strengthen the denitrification of low C/N ratio sewage according to claim 7, characterized in that the effluent from the anoxic tank (2) enters the autotrophic denitrification tank/ The water volume of the reactor (3) accounts for 70%-90% of the total water output of the anoxic tank (2). 10. The method of utilizing sulfur autotrophic denitrification to synergistically strengthen the denitrification of low C/N ratio sewage according to claim 7, characterized in that the average particle size of elemental sulfur particles is 1.0-2.0 mm.