Double-sludge-age composite denitrification reactor and method based on carbon source recovery

Abstract

The double-sludge-age composite denitrification reactor based on carbon source recovery comprises an intermediate water tank, an A2 / O reactor, a sedimentation tank and the like, and the A2 / O reactor is divided into an anaerobic zone, an anoxic zone and an aerobic zone. A sewage treatment conventional flora and an anaerobic ammonia oxidation biological membrane are cultured to form a double-sludge-age composite nitrogen removal system with coexistence of the anaerobic ammonia oxidation flora and the conventional flora and combination of long sludge age and short sludge age, and coupling of whole-course autotrophic nitrogen removal and heterotrophic nitrogen removal based on anaerobic ammonia oxidation is realized in the same reactor. The carbon source recovery effluent is subjected to anaerobic zone heterotrophic nitrogen removal, anoxic zone autotrophic nitrogen removal, aerobic zone nitration reaction and the like in the system, so that the autotrophic nitrogen removal contribution rate reaches about 22.22%, and about 20% of carbon source in the denitrification nitrogen removal process and about 12% of aeration energy consumption in the nitration process are saved; the consumption of a carbon source and a nitrogen source, the aeration energy consumption and the like can be reduced while relatively high effluent quality is ensured, and the operation cost of the system is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection and sewage treatment, and in particular relates to a double-sludge-age composite denitrification reactor and a method based on carbon source recovery. Background Art

[0002] Since my country's urban sewage has the characteristic of low C / N ratio, it is difficult to achieve maximum resource utilization directly through anaerobic treatment technology. The above problem can be solved by using carbon source recovery technology such as magnetic separation to recover carbon sources in urban sewage. After carbon source recovery treatment, urban sewage still has the characteristic of low C / N ratio. Most of my country's sewage treatment plants use technology based on nitrification-denitrification principle to treat sewage, which not only requires the addition of carbon source to enhance denitrification, but also requires higher aeration energy consumption to enhance nitrification reaction, which has the disadvantages of high carbon source consumption, high energy consumption, and high sludge production.

[0003] Autotrophic denitrification based on anaerobic ammonia oxidation is a new and economical denitrification technology with the advantages of high denitrification load, no need for carbon source addition, and low energy consumption. However, this technology faces bottleneck problems such as low ammonia nitrogen concentration, high carbon source concentration and low temperature in the application of urban sewage treatment: under low ammonia nitrogen concentration and low temperature conditions, anaerobic ammonia oxidizing bacteria grow slowly, and nitrite is difficult to regulate, resulting in nitrite oxidizing bacteria competing with anaerobic ammonia oxidizing bacteria for nitrite nitrogen, while high carbon source concentration will cause a large number of heterotrophic bacteria to reproduce and grow, competing with anaerobic ammonia oxidizing bacteria for substrates and living space, and it is difficult for the effluent to reach a high level, requiring further treatment. The present invention combines autotrophic denitrification with traditional nitrification and denitrification heterotrophic denitrification processes, taking advantage of each other's strengths and weaknesses, and achieving efficient denitrification of sewage with low carbon source consumption by coupling autotrophic denitrification and heterotrophic denitrification, thereby reducing carbon source consumption and energy consumption. Summary of the invention

[0004] In order to solve the problems of high carbon source consumption, high energy consumption and so on of the existing carbon source recovery sewage treatment technology, the present invention provides a double sludge age composite denitrification reactor and method based on carbon source recovery, which realizes efficient denitrification of sewage with low carbon source consumption by coupling autotrophic denitrification and heterotrophic denitrification, saving energy consumption and carbon source consumption.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A double-sludge-age composite denitrification reactor based on carbon source recovery, comprising an intermediate water tank, an A 2 / O reactor, sedimentation tank and central control system, the A 2 The A / O reactors are connected to the intermediate water tank and the sedimentation tank respectively. 2The / O reactor is provided with an anaerobic zone, an anoxic zone and an aerobic zone, a partition is provided between the three zones, and the three zones are connected through pipes provided on the partition, agitators are provided in the three zones, an anoxic zone is provided with an anoxic aeration system, the aerobic zone is provided with an aerobic aeration system, and an anaerobic ammonia oxidizing bacteria biofilm suspended filler is also added to the anoxic zone;

[0007] The sedimentation tank is provided with a slow agitator and an external reflux system, one end of the external reflux system is connected to the bottom of the sedimentation tank, and the other end leads to the anaerobic zone;

[0008] The stirrer, the anoxic aeration system, the aerobic aeration system, the slow stirrer and the external reflux system are all provided with circuits connected to the central control system.

[0009] The A 2 The / O reactor is also provided with an internal reflux system, one end of which is connected to the side of the aerobic zone through a pipeline, and the other end leads to the bottom of the anoxic zone. The internal reflux system is provided with a circuit connected to the central control system.

[0010] The anoxic aeration system is provided with a microporous aerator and an air pump.

[0011] The aerobic aeration system is provided with a microporous aerator and a fan.

[0012] The anaerobic ammonium oxidizing bacteria biofilm suspended filler is of K3 type.

[0013] The filling rate of the anaerobic ammonium oxidizing bacteria biofilm filler is 20%.

[0014] A double-sludge-age composite denitrification method based on carbon source recovery comprises the following steps:

[0015] Step 1: Start A 2 / O process: Inoculation of sludge in the reactor to start A 2 / O reactor, after sludge inoculation, it is activated by aeration to form a suspended sludge (short sludge age) heterotrophic denitrification zone;

[0016] Step 2: enriching anaerobic ammonium oxidizing bacteria: inoculating the suspended filler with anaerobic ammonium oxidizing bacteria biofilm in the anoxic zone and adding sodium nitrite to restore and strengthen the activity of the anaerobic ammonium oxidizing biofilm to form a biofilm (long sludge age) autotrophic denitrification zone, thereby forming a double sludge age composite denitrification system of suspended sludge (short sludge age) heterotrophic denitrification zone and biofilm (long sludge age) autotrophic denitrification zone;

[0017] Step 3: Regulate micro-aerobic nitrification: After the double-sludge-age composite denitrification system is formed, stop adding sodium nitrite, use aerobic / anoxic intermittent aeration in the anoxic zone, the aeration time is 5-20min, the dissolved oxygen concentration in the anoxic zone is controlled at 0.1-0.3mg / L, and the internal reflux system and the external reflux system are opened through the central control system at the same time;

[0018] Step 4: Normal operation: After the reactor is running stably, the anoxic zone is aerated intermittently, the internal reflux system is closed through the central control system and the external reflux ratio of the external reflux system is controlled to 100%.

[0019] The time of the activation by exposure to air is 3 days.

[0020] The aeration time of the intermittent aeration is 15 minutes aerobic / 15 minutes anoxic.

[0021] In the step three, the internal reflux ratio is 0%-150%, and the external reflux ratio is 100%.

[0022] Compared with the prior art, the dual-sludge-age composite denitrification reactor and method based on carbon source recovery of the present invention has the following characteristics and beneficial effects:

[0023] 1. By cultivating conventional sewage treatment bacteria and anaerobic ammonium oxidation biofilm in the same reactor, a dual-sludge-age composite denitrification system with coexistence of anaerobic ammonium oxidation bacteria and conventional bacteria, and a combination of long sludge age and short sludge age is formed, and the coupling of full-process autotrophic denitrification and heterotrophic denitrification based on anaerobic ammonium oxidation is realized in the same reactor. Compared with the existing technology, this system not only does not require an external carbon source during operation, but also saves about 20% of carbon source in the denitrification denitrification process, and about 12% of aeration energy consumption in the nitrification process. Therefore, the system can reduce carbon source consumption and energy consumption while ensuring high effluent quality;

[0024] 2. The denitrification effect of the present invention without adding a nitrogen source is not much different from the denitrification effect of adding a nitrogen source in the prior art, so the present invention can save nitrogen sources compared with the prior art;

[0025] 3. In the present invention, autotrophic denitrification and heterotrophic denitrification are combined, and the contribution rate of autotrophic denitrification is above 20%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of a dual-sludge-age composite denitrification reactor based on carbon source recovery according to an embodiment of the present invention;

[0027] Figure 2 The present invention is a flow chart of a dual-sludge-age composite denitrification method based on carbon source recovery according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.

[0029] In order to solve the problems of high energy consumption and high carbon source consumption in the existing carbon source recovery sewage treatment technology, a dual-sludge-age composite denitrification reactor and method based on carbon source recovery is provided in the present invention, which realizes the coupling of full-process autotrophic denitrification and heterotrophic denitrification based on anaerobic ammonia oxidation in the same reactor, thereby achieving the purpose of efficient denitrification of sewage with low carbon source consumption, saving energy consumption and saving carbon source consumption.

[0030] like Figure 1 As shown, a double-sludge-age composite denitrification reactor based on carbon source recovery includes an intermediate water tank 1, A 2 / O reactor 2, sedimentation tank 3 and central control system 4, the A 2 / O reactor 2 is connected to intermediate water tank 1 and sedimentation tank 3 respectively. The water in intermediate water tank 1 is pumped into the reactor through water inlet pump 1.1. 2 The / O reactor is provided with an anaerobic zone a, an anoxic zone b and an aerobic zone c, a partition 2.1 is provided between the three zones, and the three zones are connected through a pipeline provided on the partition 2.1, and a stirrer 2.2 is provided in each of the three zones, an anoxic zone b is provided with an anoxic aeration system, and the aerobic zone c is provided with an aerobic aeration system, and an anaerobic ammonia oxidizing bacteria biofilm suspension filler 2.6 is also added to the anoxic zone b;

[0031] The sedimentation tank 3 is provided with a slow agitator 3.1 and an external reflow system, one end of which is connected to the bottom of the sedimentation tank 3 and the other end is connected to the anaerobic zone a. The precipitated sludge at the bottom of the sedimentation tank 3 is returned to the anaerobic zone a through the external reflow pump 3.2.

[0032] The A 2 The / O reactor is also provided with an internal reflux system, one end of which is connected to the side of the aerobic zone c through a pipeline, and the other end leads to the bottom of the anoxic zone b, and the sludge from the aerobic zone c is refluxed to the anoxic zone b through the internal reflux pump 2.7.

[0033] The anoxic aeration system is provided with a microporous aerator 2.3 and an air pump 2.5.

[0034] The aerobic aeration system is provided with a microporous aerator 2.3 and a fan 2.4.

[0035] The anaerobic ammonia oxidizing bacteria biofilm suspension filler 2.6 can be selected as K3 type, and the filling rate is about 20%.

[0036] The water inlet pump 1.1, the stirrer 2.2, the fan 2.4, the air pump 2.5, the internal reflux pump 2.7, the slow stirrer 3.1 and the external reflux pump 3.2 are all provided with circuits connected to the central control system 4.

[0037] The central control system 4 adjusts the agitator 2.2 through the frequency converter to ensure that the suspended sludge and suspended filler in the reactor are in a good mixed state. The central control system 4 adjusts the speed of the slow agitator 3.1 through the frequency converter to prevent dead sludge; the operating frequency of the fan 2.4 and the air pump 2.5 can be adjusted through the frequency converter, so as to achieve precise control of the aeration amount of the reactor; the shaft power of the water inlet pump 1.1, the internal reflux pump 2.7 and the external reflux pump 3.2 can be adjusted through the frequency converter, so as to achieve precise control of the water inlet flow rate and the internal and external reflux amounts.

[0038] like Figure 2 As shown, a dual-sludge-age composite denitrification method based on carbon source recovery comprises the following steps:

[0039] Step 1: Start A 2 / O process: Inoculation of sludge in the reactor to start A 2 / O reactor, after sludge inoculation, it is activated by air drenching for about 3 days to form a suspended sludge (short sludge age) heterotrophic denitrification zone;

[0040] Step 2, enriching anaerobic ammonia-oxidizing bacteria: inoculating 2.6 suspended fillers with anaerobic ammonia-oxidizing bacteria biofilm in the anoxic zone b and adding sodium nitrite to restore and strengthen the activity of the anaerobic ammonia-oxidizing biofilm, the concentration of the added sodium nitrite is from low to high, the concentration is between 2-10 mg / L, the filler filling rate is about 20%, after the anoxic zone b forms a biofilm (long sludge age) autotrophic denitrification zone, a double sludge age composite denitrification system of suspended sludge (short sludge age) heterotrophic denitrification zone and biofilm (long sludge age) autotrophic denitrification zone is formed in the reactor;

[0041] Step 3, regulating micro-aerobic nitrification: after the double-sludge-age composite denitrification system is formed, stop adding sodium nitrite, and at the same time, open the internal reflux system and the external reflux system through the central control system 4, and adopt aerobic / anoxic intermittent aeration in the anoxic zone b, and the aeration time is 5-20min, preferably 15min. During aerobic aeration, the anoxic aeration system is opened through the central control system to control the dissolved oxygen concentration at 0.1-0.3mg / L, and during anoxic aeration, the anoxic aeration system is closed;

[0042] Step 4, regulating the internal and external reflux system: adjust the internal and external reflux ratio of the internal and external reflux system through the central control system 4, so that the internal reflux ratio is gradually adjusted from 0%-150% to 0%, thereby further increasing the ammonia nitrogen concentration of the anoxic zone inlet water and strengthening the autotrophic denitrification process. During this period, the ammonia nitrogen concentration of the inlet and outlet water is measured to ensure that the reduction in the internal reflux amount will not significantly affect the denitrification effect of the reactor, and finally close the internal reflux system; control the external reflux ratio at 100%.

[0043] When the reactor is running stably, the anoxic aeration system is regulated by the central control system 4 to maintain intermittent aeration in the anoxic zone b, the external reflow ratio of the external reflow system is adjusted to 100%, and the aerobic aeration system is adjusted to maintain the dissolved oxygen concentration in the aerobic zone c at 1-3 mg / L. After the sewage is treated with double sludge age composite denitrification and nitrification in the aerobic zone c, the effluent ammonia nitrogen is ≤2 mg / L, the total nitrogen is ≤10 mg / L, and the effluent water quality is stable.

[0044] In the embodiment, the specifications of the reactor 2 can be selected to be 3.60m long, 1.20m wide, 2.00m high, and 8.64m in volume. 3 , effective volume is 7.80m 3 The length, width and height of the sedimentation tank 3 can be selected as 1.20m, 1.20m, 1.80m, and the overflow height can be set to 1.60m; intermittent aeration of 15min aerobic / 15min anoxic is selected; the ambient temperature is 18-22℃.

[0045] Among them, the average effluent ammonia nitrogen and total nitrogen concentrations in step one are 2.60±4.30mg / L and 11.60±3.80mg / L, respectively, and the average removal rates of ammonia nitrogen and total nitrogen are 87.80% and 47.90%, respectively; the average effluent ammonia nitrogen in step two is 0.71mg / L, the average effluent total inorganic nitrogen concentration is 7.19±1.47mg / L, and the average removal rates of ammonia nitrogen and total nitrogen are 94.11% and 71.47%, respectively; the average effluent ammonia nitrogen in step three is 1.00mg / L, the total nitrogen is 8.84mg / L, and the ammonia nitrogen removal rate and total nitrogen removal rate are 97.00% and 74.00%, respectively. It can be seen that the effluent water quality in step one does not meet the A-level standard of Beijing's "Water Pollutant Discharge Standards for Urban Wastewater Treatment Plants" (DB11 / 890-2012), and the effluent water quality in steps two and three can meet the above standards. This is because step one is equivalent to traditional A 2 / O process without adding an external carbon source, the effluent water quality requires an external carbon source to meet the discharge standards in engineering; step two is equivalent to the traditional anaerobic ammonia oxidation process, which requires continuous addition of a nitrogen source to ensure the effluent water quality, and the effluent water quality is easily affected by the influent ammonia nitrogen concentration, etc.; in step three, the double-sludge-age composite denitrification process of the present invention does not require external carbon source and nitrogen source, indicating that after regulating the micro-aerobic nitrite, the system does not need to add an external carbon source and nitrogen source.

[0046] Calculations show that the contribution rate of autotrophic denitrification in the present invention reaches about 22.22%, while also being able to save about 20% of the carbon source in the denitrification process and about 12% of the aeration energy consumption in the nitrification process.

[0047] In addition, after comparative studies, it was found that traditional A 2When the / O process is used to treat the carbon source recovery effluent (C / N<3), the total nitrogen concentration of the effluent is 11.6±3.8 mg / L when no carbon source is added, which cannot meet the A-level standard of Beijing's "Water Pollutant Discharge Standard for Urban Sewage Treatment Plants" (DB11 / 890-2012). In order to meet this standard, based on the influent carbon source of 108 mg / L, an additional addition of about 70 mg / L of carbon source is required to make the effluent total nitrogen concentration about 9 mg / L. When treating the same carbon source recovery effluent (C / N<3), the total nitrogen in the effluent of the present invention is lower than the A-level standard limit of Beijing's "Water Pollutant Discharge Standard for Urban Sewage Treatment Plants" (DB11 / 890-2012), and the effluent water quality is stable. Therefore, it can be considered that when treating the same carbon source recovery effluent (C / N<3), the present invention is superior to the traditional A-level standard. 2 The / O process saves about 65% of carbon source.

[0048] The double-sludge-age composite denitrification reactor and method based on carbon source recovery of the present invention realizes the complementary advantages of autotrophic denitrification and heterotrophic denitrification double-sludge-age composite denitrification in the same reactor, thereby reducing carbon source consumption and energy consumption, the contribution rate of autotrophic denitrification is more than 20%, and about 20% of the carbon source in the denitrification denitrification process and about 12% of the aeration energy consumption in the nitrification process are saved; in a comparative study, it can even save about 65% of the carbon source.

[0049] For ordinary technicians in this technical field, based on the above principles, several changes and improvements can be made to the reactor and method of the present invention, and these changes and improvements should also be included in the scope of protection of the present invention.

Claims

1. A dual-sludge-age composite denitrification reactor based on carbon source recovery, characterized in that: It includes an intermediate water tank (1), A 2 / O reactor (2), sedimentation tank (3) and central control system (4), the A 2 The A / O reactor (2) is connected to the intermediate water tank (1) and the sedimentation tank (3) respectively. 2 An anaerobic zone (a), an anoxic zone (b) and an aerobic zone (c) are provided in the reactor, a partition (2.1) is provided between the three zones, and the three zones are connected via a pipeline provided on the partition (2.1), a stirrer (2.2) is provided in each of the three zones, an anoxic zone (b) is provided with an anoxic aeration system, and the aerobic zone (c) is provided with an aerobic aeration system, and an anaerobic ammonia-oxidizing bacteria biofilm suspended filler (2.6) is also added to the anoxic zone (b); The sedimentation tank (3) is provided with a slow agitator (3.1) and an external reflux system, one end of the external reflux system is connected to the bottom of the sedimentation tank (3), and the other end is connected to the anaerobic zone (a); The stirrer (2.2), the anoxic aeration system, the aerobic aeration system, the slow stirrer (3.1) and the external reflux system are all provided with circuits connected to the central control system (4).

2. A dual-sludge-age composite denitrification reactor based on carbon source recovery according to claim 1, characterized in that: The A 2 The / O reactor is also provided with an internal reflux system, one end of which is connected to the side of the aerobic zone (c) through a pipeline, and the other end leads to the bottom of the anoxic zone (b). The internal reflux system is provided with a circuit connected to the central control system (4).

3. A dual-sludge-age composite denitrification reactor based on carbon source recovery according to claim 1, characterized in that: The anoxic aeration system is provided with a microporous aerator (2.3) and an air pump (2.5).

4. A dual-sludge-age composite denitrification reactor based on carbon source recovery according to claim 1, characterized in that: The aerobic aeration system is provided with a microporous aerator (2.3) and a fan (2.4).

5. A dual-sludge-age composite denitrification reactor based on carbon source recovery according to claim 1, characterized in that: The anaerobic ammonium oxidizing bacteria biofilm suspended filler (2.6) is of K3 type.

6. A dual-sludge-age composite denitrification reactor based on carbon source recovery according to claim 1, characterized in that: The filling rate of the anaerobic ammonium oxidizing bacteria biofilm suspension filler is 20%.

7. A dual-sludge-age composite denitrification method based on carbon source recovery, characterized in that: The steps include: Step 1: Start A 2 / O process: Inoculation of sludge in the reactor to start A 2 / O reactor, after sludge inoculation, it is activated by aeration to form a suspended sludge (short sludge age) heterotrophic denitrification zone; Step 2, enriching anaerobic ammonium oxidizing bacteria: inoculating the suspended filler (2.6) attached with anaerobic ammonium oxidizing bacteria biofilm in the anoxic zone (b) and adding sodium nitrite to restore and strengthen the activity of the anaerobic ammonium oxidizing biofilm to form a biofilm (long sludge age) autotrophic denitrification zone, thereby forming a double sludge age composite denitrification system of a suspended sludge (short sludge age) heterotrophic denitrification zone and a biofilm (long sludge age) autotrophic denitrification zone; Step 3, regulating micro-aerobic nitrification: after the double-sludge-age composite denitrification system is formed, stop adding sodium nitrite, adopt aerobic / anoxic intermittent aeration in the anoxic zone (b), the aeration time is 5-20min, the dissolved oxygen concentration in the anoxic zone (b) is controlled at 0.1-0.3mg / L during aeration, and at the same time, start the internal reflux system and the external reflux system through the central control system (4); Step 4, regulating the internal and external reflux systems: adjusting the internal and external reflux ratios of the internal and external reflux systems through the central control system (4) so ​​that the internal reflux ratio is 0% and the external reflux ratio is 100%.

8. A dual-sludge-age composite denitrification method based on carbon source recovery according to claim 7, characterized in that: The time of the activation by exposure to air is 3 days.

9. A dual-sludge-age composite denitrification method based on carbon source recovery according to claim 7, characterized in that: The aeration time of the intermittent aeration is 15 minutes aerobic / 15 minutes anoxic.

10. A dual-sludge-age composite denitrification method based on carbon source recovery according to claim 7, characterized in that: In the step 3, the internal reflux ratio is 0%-150%, and the external reflux ratio is 100%.

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