CN103058375B - Anaerobic-aerobic process control method for efficient phosphorus removal and nitrogen reservation of municipal domestic sewage - Google Patents

Abstract

The invention relates to an anaerobic-aerobic process control method for efficiently removing phosphorus and retaining nitrogen in urban domestic sewage, which belongs to the field of urban domestic sewage treatment and resource utilization. The whole process of sewage regeneration represented by anaerobic-aerobic phosphorus removal and organic matter removal, followed by autotrophic denitrification process for nitrogen removal is an effective way to achieve low-carbon and efficient sewage treatment. For the anaerobic-aerobic phosphorus removal process in the whole process , since the subsequent autotrophic denitrification process has no phosphorus removal function and ammonia nitrogen is used as the influent, the total phosphorus in the effluent should be less than 0.5mg/L to meet the first-level A standard, and the nitrogen should be retained as much as possible without conversion and low loss. Under normal temperature conditions, using domestic sewage as the basis of water, the control parameters for the anaerobic-aerobic process at different temperatures are proposed. By implementing gradient oxygen limitation, the sludge age is strictly controlled, ammonia oxidation and denitrification are inhibited, and anaerobic Oxygen-aerobic process efficiently removes phosphorus and operates with low nitrogen loss.

Description

An anaerobic-aerobic process control method for efficient phosphorus removal and nitrogen retention in urban domestic sewage

technical field

The invention belongs to the field of urban domestic sewage treatment and resource utilization, and in particular relates to an anaerobic-aerobic process control method for highly efficient phosphorus removal and nitrogen retention.

Background technique

Up-to-standard discharge of sewage treatment is an important means to alleviate the crisis of water environment. China's sewage treatment plants mainly adopt the following three treatment processes: A ² /O activated sludge process, oxidation ditch and SBR. The expected goal of the A ² /O process is to remove both N and P biologically while removing organic pollution. However, the actual operation experience shows that since both denitrification and biological phosphorus removal need to consume carbon sources, there is a problem of competition for carbon sources. Moreover, there are differences in dissolved oxygen and sludge age between phosphorus removal bacteria and denitrification bacteria. The effect of nitrogen and phosphorus removal is not ideal. Oxidation ditch process forms an anoxic and aerobic alternate area in the ditch, which is conducive to nitrification and denitrification reactions. Although this process can obtain a certain denitrification effect, it cannot achieve the first-class A standard for discharge water. Although the SBR process can achieve the removal of organic matter, nitrification, and phosphorus absorption by controlling the aeration time, the anaerobic and anoxic state in the reactor can be achieved by controlling the aeration or stirring intensity, thereby completing the biological phosphorus removal and denitrification process. However, this process has the same disadvantages as A ² /O and oxidation ditch, that is, the survival competition between phosphorus-removing bacteria and nitrogen-removing bacteria. Therefore, it is difficult to achieve the first-class A standard of TN and P in the discharged water. The existing secondary sewage treatment process transformation projects are almost all based on the secondary treatment process, supplementing the advanced treatment process. That is, it is customary to consider the advanced treatment of sewage in stages, and then combine them with simple machinery to achieve advanced treatment of sewage. The actual operation of the project shows that such an upgrade not only wastes a lot of energy and material consumption, but also the treatment effect is not ideal. The fundamental reason is that there are unreasonable, uneconomical or even errors in the removal types and loads of pollutants that each unit structure undertakes in the corresponding treatment process. Therefore, the upgrading and transformation of sewage treatment plants should be considered from the overall overall process flow, clarify and adjust the tasks of each treatment unit and optimize its corresponding organic load. From the perspective of process technology, we should combine the existing process flow and site conditions of sewage treatment plants to develop key technologies for advanced sewage treatment that are simple in process, easy to operate and maintain, so as to achieve stable and efficient discharge water to meet Class A discharge standards; from economic operation From the point of view, the energy and material consumption of aeration and chemical dosing should be reduced as much as possible to achieve a low-carbon economy.

Since it is impossible for N and P to be deeply removed in one reactor at the same time, it should be realized step by step in different reactors. Biological phosphorus removal can save a lot of operating costs because no chemicals are added, and organic matter can be removed at the same time as biological phosphorus removal, so the biological phosphorus removal unit can be strengthened to achieve deep removal of phosphorus and organic matter, which is also fully in line with low-carbon economy The goal. Since a large amount of organic matter is also removed during the biological phosphorus removal, a series of denitrification processes centered on the autotrophic denitrification process should be adopted in the process of the denitrification unit without adding carbon sources. The anaerobic ammonium oxidation (ANAMMOX) phenomenon discovered in the 1990s provided the possibility for this idea, and provided a new idea for the ultimate low-carbon and efficient treatment of domestic sewage.

The whole process of sewage regeneration, through anaerobic-aerobic phosphorus removal and organic matter removal, followed by autotrophic denitrification process, realizes low-carbon and efficient removal of urban domestic sewage. The whole process of sewage regeneration puts forward new requirements for the A/O process. Since the subsequent autotrophic denitrification unit absorbs a small amount of phosphorus in addition to biological assimilation, it basically has no phosphorus removal function. The phosphorus removal is completely dependent on the A/O process, and the A/O phosphorus removal effect should reach or approach the first-level A level. The autotrophic denitrification process cannot tolerate high COD and low nitrogen substrates at the same time. A/O needs to remove as much organic matter as possible and retain as much ammonia nitrogen in the water as possible so that it does not transform and has low loss.

However, when the traditional A/O phosphorus removal process is running, it does not regulate nitrogen, and often the loss of ammonia nitrogen exceeds 50%, and the loss of total nitrogen exceeds 40%, which is extremely unfavorable to the subsequent autotrophic denitrification process, and there is a large amount of denitrification. Competing with phosphorus-accumulating bacteria in the anaerobic zone for carbon sources, reducing the efficiency of phosphorus removal. Generally, when the traditional A/O process is in operation, the phosphorus removal rate is maintained at about 80%, which is difficult to further improve. In view of this, on the basis of the traditional anaerobic-aerobic phosphorus removal process, it is imperative to propose a new A/O phosphorus removal process with high efficiency and low nitrogen loss.

Contents of the invention

The purpose of the invention is to provide an anaerobic-aerobic process regulation method with high efficiency phosphorus removal and low nitrogen loss.

The present invention uses domestic sewage as the basis of water at room temperature, proposes control parameters for the anaerobic-aerobic process at different temperatures, and realizes the efficient dephosphorization and low nitrogen loss operation of the A/O process, which is characterized in that:

When the temperature is 12-18°C, the organic load of the influent is controlled to be 0.4-0.6kgCOD/m ³ /d, the residence time ratio of the anaerobic zone and the aerobic zone is 1:4, and the volume ratio of the aerobic zone is 1:1: 1 is divided into three dissolved oxygen gradients, respectively 1.4-1.5, 1.1-1.2, 0.7-0.8mg/L, the sludge concentration is controlled at 2.0-3.0g/L, the sludge reflux ratio is 40-50%, and the sludge Age is 5-7d;

When the temperature is 18-25°C, the organic load of the influent is controlled to be 0.5-0.7kgCOD/m ³ /d, the residence time ratio of the anaerobic zone and the aerobic zone is 1:3, and the volume ratio of the aerobic zone is 1:1: 1 is divided into three dissolved oxygen gradients, respectively 1.0-1.1, 0.6-0.7, 0.4-0.5mg/L, the sludge concentration is controlled at 2.5-3.5g/L, the sludge reflux ratio is 30-40%, and the sludge The age is 4-6d.

Compared with the existing method for starting nitrosation granular sludge, the present invention has the following beneficial effects:

1) The present invention proposes operating parameters of the A/O process for different temperature ranges to achieve efficient phosphorus removal;

2) Aiming at the new mission of A/O in the whole process of sewage regeneration, the present invention proposes the control parameters of the A/O process to achieve low nitrogen loss under high-efficiency phosphorus removal;

3) The total phosphorus removal rate is greater than 90%, which is higher than the general A/O phosphorus removal process;

4) The loss of ammonia nitrogen is less than 20%, the loss of total nitrogen is less than 25%, there is no accumulation of nitrite nitrogen and nitrate nitrogen, and there is basically no denitrification. The loss of nitrogen is mainly due to biological assimilation, which satisfies the removal of total phosphorus in the whole process And for the supply of subsequent nitrogen.

Description of drawings

Figure 1 is a schematic diagram of the reactor. The test device is composed of two parts: the reaction tank and the secondary sedimentation tank. The effective volume of the reaction tank is 1083L, and its length, width and height are 2m, 0.6m and 1m respectively, and it is divided into anaerobic zone and aerobic zone. , separated by a perforated partition in the middle. The anaerobic tank is equipped with a mixer, which is a complete mixing type; the aerobic tank is a plug-flow type, and three aeration devices are evenly installed along the bottom. The secondary settling tank is a vertical flow settling tank, with central water inlet and peripheral water outlet.

Among them, (1) data acquisition system (2) mixer (3) rotameter (4) ORP probe (5) conductivity probe (6) pH probe (7) DO probe (8) aeration head (9) secondary sedimentation Pool (10) gas flow meter (11) air compressor (12) domestic sewage pump (13) sludge return pump (14) automatic sludge discharge valve.

Figure 2 is the operating effect of the reactor at a temperature of 13-16°C during winter. Nv _COD means COD volume load, that is, the amount of organic matter processed per unit volume reactor per day, kgCOD/m ³ /d, OrgN means organic nitrogen, inf means influent water, eff means effluent water. Before regulation, that is, 0-15 days, the average total phosphorus in the effluent was 1.21mg/L, the average total phosphorus removal rate was 80.95%, the average ammonia nitrogen loss rate was as high as 46.14%, and the average total nitrogen loss rate was as high as 41.85%. After regulation, that is, starting from 16 days to the 55th day of operation, the average total phosphorus in the effluent is 0.44mg/L, the average removal rate of total phosphorus is 93.02%, the total phosphorus in the effluent reaches the first-class A standard, and the average loss rate of ammonia nitrogen is only 12.74%. The average total nitrogen loss rate was only 20.61%.

Figure 3 is the nitrogen relationship diagram along the reactor during the winter period when the reactor runs to the 53rd day. Since the influent and reflux are mixed in the anaerobic section, the ammonia nitrogen decreases rapidly in the anaerobic section, and the ammonia nitrogen basically remains stable when entering the aerobic section. Oxidation of some organic nitrogen led to a slight increase in ammonia nitrogen in the effluent, but no accumulation of nitrite nitrogen and nitrate nitrogen in the whole process, and the loss of ammonia nitrogen was mainly used for biological assimilation.

Figure 4 shows the effect of reactor operation at a temperature of 22-24°C during summer. Nv _COD means COD volume load, that is, the amount of organic matter processed per unit volume reactor per day, kgCOD/m ³ /d, OrgN means organic nitrogen, inf means influent water, eff means effluent water. Before regulation, that is, 0-15 days, the average effluent total phosphorus is 1.08mg/L, the average removal rate of total phosphorus is 82.13%, the average loss rate of ammonia nitrogen is as high as 61.00%, and the average loss rate of total nitrogen is as high as 56.63%; after regulation, that is, 16 days , until the 50th day of operation, the average effluent total phosphorus was 0.44mg/L, the average total phosphorus removal rate was 93.02%, the effluent total phosphorus reached the first-class A standard, the average ammonia nitrogen loss rate was only 12.74%, and the average total nitrogen loss rate was only The total phosphorus in the effluent is 20.61%; the average total phosphorus in the effluent is 0.46mg/L, and the average total phosphorus removal rate is 92.40%. .

Figure 5 is a diagram of the nitrogen relationship along the reactor during the reactor operation to the 47th day during the summer. Since the influent and reflux are mixed in the anaerobic section, the ammonia nitrogen in the anaerobic section decreases rapidly, and enters the aerobic section, and the ammonia nitrogen basically remains stable. Oxidation of some organic nitrogen led to a slight increase of ammonia nitrogen in the effluent, but no accumulation of nitrite nitrogen and nitrate nitrogen in the whole process, and the loss of ammonia nitrogen was mainly used for biological assimilation.

Detailed ways

Example 1:

The test was carried out under the condition of 13-16°C, with urban domestic sewage as the influent. The test device consists of two parts, the reaction tank and the secondary sedimentation tank. The effective volume of the reaction tank is 1083L, and its length, width and height are 2m, 0.6m and 1m respectively. It is divided into anaerobic zone and aerobic zone, separated by a perforated partition in the middle . The anaerobic tank is equipped with a mixer, which is a complete mixing type; the aerobic tank is a plug-flow type, and three aeration devices are evenly installed along the bottom. The secondary settling tank is a vertical flow settling tank, with central water inlet and peripheral water outlet.

The test is divided into two parts, 0-15d is operated according to the design control parameters of the anaerobic-aerobic phosphorus removal process in the GB50014-2006 outdoor drainage design specification, and 16-55d is operated according to the control parameters of the present invention to compare phosphorus removal and Nitrogen loss effect.

0-15d control the influent organic load to 1.0±0.1kgCOD/m ³ /d, the residence time ratio of the anaerobic zone to the aerobic zone is 1:4, the dissolved oxygen in the aerobic zone is controlled at 2.0-2.5mg/L, and the sludge The concentration is maintained at 2.4-2.7g/L, the sludge return ratio is 40-50%, and the sludge age is 6-7d; the average total phosphorus in the effluent is 1.21mg/L, the average total phosphorus removal rate is 80.95%, and the average ammonia nitrogen loss The rate is as high as 46.14%, and the average total nitrogen loss rate is as high as 41.85%.

From 16 days onwards, reduce the influent organic load to 0.6±0.05kgCOD/m ³ /d, and the aerobic zone is divided into three dissolved oxygen gradients according to the volume ratio of 1:1:1, which are 1.4-1.5, 1.1-1.2, 0.7-0.8 mg/L, the sludge reflux ratio is reduced to 40-45%, the sludge age is controlled to 5-6d, the effluent effect is stable until 25d, and then it runs stably, the average total phosphorus in the effluent is 0.44mg/L, and the total phosphorus removal rate The average is 93.02%, the total phosphorus in the effluent reaches the first-class A standard, the average ammonia nitrogen loss rate is only 12.74%, and the average total nitrogen loss rate is only 20.61%.

Example 2

The test was carried out under the condition of 22-24°C, with urban domestic sewage as the influent. The test device consists of two parts, the reaction tank and the secondary sedimentation tank. The effective volume of the reaction tank is 1083L, and its length, width and height are 2m, 0.6m and 1m respectively. It is divided into anaerobic zone and aerobic zone, separated by a perforated partition in the middle . The anaerobic tank is equipped with a mixer, which is a complete mixing type; the aerobic tank is a plug-flow type, and three aeration devices are evenly installed along the bottom. The secondary settling tank is a vertical flow settling tank, with central water inlet and peripheral water outlet.

The test is divided into two parts, 0-15d is operated according to the design control parameters of the anaerobic-aerobic phosphorus removal process in the GB50014-2006 outdoor drainage design specification, and 16-50d is operated according to the control parameters of the present invention to compare phosphorus removal and Nitrogen loss effect.

0-15d control the influent organic load to 1.0±0.1kgCOD/m ³ /d, the residence time ratio of the anaerobic zone to the aerobic zone is 1:3, the dissolved oxygen in the aerobic zone is controlled at 2.0-2.5mg/L, and the sludge The concentration is maintained at 2.8-3.2g/L, the sludge return ratio is 35-45%, and the sludge age is 5-6d; the average total phosphorus in the effluent is 1.08mg/L, the average total phosphorus removal rate is 82.13%, and the average ammonia nitrogen loss The rate is as high as 61.00%, and the average total nitrogen loss rate is as high as 56.63%.

From 16 days onwards, reduce the influent organic load to 0.7±0.05kgCOD/m ³ /d, and the aerobic zone is divided into three dissolved oxygen gradients according to the volume ratio of 1:1:1, which are 1.0-1.1, 0.6-0.7, and 0.4-0.5 mg/L, the sludge reflux ratio is reduced to 35-40%, and the sludge age is controlled to 4-5d. After 26 days of operation, the effluent was basically stable, and after that, the average effluent total phosphorus was 0.46mg/L, the average total phosphorus removal rate was 92.40%, the effluent total phosphorus reached the first-class A standard, and the average ammonia nitrogen loss rate was only 17.69%. The total nitrogen loss rate is only 23.58%.

Claims (1)

1. An anaerobic-aerobic process control method for efficiently removing phosphorus and retaining nitrogen from urban domestic sewage, characterized in that: When the temperature is 13-16°C, the organic load of the influent is controlled to be 0.55-0.65kgCOD/m ³ /d, the residence time ratio of the anaerobic zone and the aerobic zone is 1:4, and the aerobic zone is divided according to 1:1:1 There are three dissolved oxygen gradients, respectively 1.4-1.5, 1.1-1.2, 0.7-0.8mg/L, the sludge concentration is controlled at 2.0-3.0g/L, the sludge reflux ratio is 40-45%, and the sludge age is 5-6d; When the temperature is 22-24°C, the organic load of the influent is controlled to be 0.65-0.75kgCOD/m ³ /d, the residence time ratio of the anaerobic zone to the aerobic zone is 1:3, and the aerobic zone is divided according to 1:1:1 There are three dissolved oxygen gradients, respectively 1.0-1.1, 0.6-0.7, 0.4-0.5mg/L, the sludge concentration is controlled at 2.5-3.5g/L, the sludge reflux ratio is 35-40%, and the sludge age is 4-5d.

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