Device and method for enhancing biological sewage treatment performance by using sludge alkaline fermentation liquor

Abstract

The invention discloses a device and a method for enhancing biological sewage treatment performance by using sludge alkaline fermentation liquor, and solves the technical problems of high energy consumption and complicated operation in the prior art. Comprising a grating, a primary sedimentation tank, an anoxic tank, an aerobic tank, a secondary sedimentation tank, a sludge mixing tank, a sludge alkaline fermentation tank, a sludge conditioning tank and a filter press, guide plates are arranged in the middle of the anoxic tank, suspended biological filler is arranged between the plates, combined filler is arranged in the middle of the aerobic tank, and the filter press is arranged in the anoxic tank. The sludge conditioning tank is provided with an acid dosing tank, a coagulant dosing tank, a magnesium chloride dosing tank and a rapid stirrer. The sewage treatment performance can be effectively improved, the total nitrogen removal rate is increased, the treatment load of an anoxic tank is increased, the operation stability of a sewage treatment system is enhanced, the addition amount of an external carbon source is reduced, the sludge volume is reduced, and the carbon emission of a sewage plant is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of sewage and sludge treatment, and in particular to a device and method for enhancing sewage biological treatment performance by utilizing sludge alkaline fermentation liquid. Background Art

[0002] The stable and efficient removal of total nitrogen in sewage is an important task facing urban sewage treatment plants. Urban sewage treatment plants generally have the problem of low influent carbon-nitrogen ratio resulting in poor denitrification effect. Sewage treatment plants mostly achieve the purpose of efficient denitrification by adding carbon sources such as sodium acetate, but this will significantly increase the operating costs of urban sewage treatment plants. Finding economical and efficient carbon sources is an urgent need facing sewage treatment plants, and it has important practical significance for the stable and efficient removal of total nitrogen in sewage. Biological treatment of sewage is accompanied by the generation of a large amount of excess sludge. Alkaline fermentation can effectively promote the hydrolysis and acidification of excess sludge and accumulate high concentrations of volatile fatty acids in the fermentation broth. Using excess sludge alkaline fermentation broth (SAFL) as a carbon source for biological denitrification can effectively improve the removal efficiency of total nitrogen and promote the reduction and resource utilization of sludge.

[0003] However, since the activity of acid-producing microorganisms in fermentation is inhibited in an alkaline environment, a large amount of dissolved organic matter in SAFL has not been converted into volatile fatty acids, which in turn limits the improvement of the quality of sludge alkaline fermentation liquid. On the other hand, SAFL also contains a large amount of difficult-to-degrade organic matter such as humic acid, which, as a carbon source, will cause an increase in dissolved organic matter (DOM) in the effluent of the biological denitrification process. DOM is a key factor affecting the effluent quality of sewage treatment plants and the main factor restricting the deep treatment and reuse of secondary effluent. As a precursor of disinfection by-products, it will increase the environmental risk of effluent being discharged into natural water bodies. Therefore, it is urgent to explore the enhancement technology of volatile fatty acids produced by sludge alkaline fermentation microorganisms and find a method to control DOM in the effluent of biological denitrification processes when SAFL is used as a carbon source.

[0004] Domestic and foreign researchers have studied methods to improve the acid production of sludge alkaline fermentation, mainly including pretreatment technology, pH gradient control method, etc. Pretreatment technology mainly improves the hydrolysis efficiency of sludge by means of high temperature, ferrate, etc., thereby promoting acid production; pH gradient control method mainly controls the pH of the fermentation process step by step, first promoting sludge hydrolysis by a higher pH, and then lowering the pH to promote the enrichment and activity of hydrolytic acidifying bacteria. These methods can effectively improve the sludge hydrolysis and acidification effect, but these methods often have problems such as high energy consumption and complex operation, which limits the application of these technical methods. In addition, there are currently few reports on the control methods of DOM in the effluent of biological denitrification process when SAFL is used as a carbon source. The above problems greatly limit the application of sludge alkaline fermentation broth to promote sewage biological treatment. Therefore, it is of great practical significance to explore measures to efficiently enhance the performance of sewage biological treatment using sludge alkaline fermentation broth. Summary of the invention

[0005] The technical problem solved by the present invention is: in view of the disadvantage that a large amount of soluble organic matter still exists in the process of sludge alkaline fermentation and has not been converted into volatile fatty acids, which limits the improvement of the quality of the sludge alkaline fermentation liquid, and the problem that SAFL contains a large amount of humic acid and other difficult-to-degrade organic matter, which leads to an increase in the soluble organic matter in the effluent of the biological denitrification process. A process device and method for efficiently enhancing the biological treatment performance of sewage by utilizing sludge alkaline fermentation liquid are provided. On the basis of ensuring the improvement of the performance of volatile fatty acids produced by sludge alkaline fermentation, the DOM in the effluent of the biological denitrification process when SAFL is used as a carbon source can be effectively reduced, the denitrification effect is good, the sludge resource utilization efficiency is high, the energy consumption is low, the operation and management are convenient, and the process operation is stable.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] In the first aspect, the present invention provides a device for enhancing the biological treatment performance of sewage by using sludge alkaline fermentation liquid, comprising a grille, a primary sedimentation tank, an anoxic tank, an aerobic tank, a secondary sedimentation tank, a sludge mixing tank, a sludge alkaline fermentation tank, a sludge conditioning tank and a filter press; wherein the grille is connected to the primary sedimentation tank, the first outlet of the primary sedimentation tank is connected to the inlet of the anoxic tank, the second outlet of the primary sedimentation tank is connected to the inlet of the sludge mixing tank, the outlet of the anoxic tank is connected to the inlet of the aerobic tank, the first outlet of the aerobic tank is connected to the secondary sedimentation tank, the second outlet of the aerobic tank is connected to the anoxic tank, and the The first outlet of the secondary sedimentation tank is connected to an external pipeline, the second outlet of the secondary sedimentation tank is connected to the anoxic tank and the sludge mixing tank respectively, the outlet of the sludge mixing tank is connected to the inlet of the sludge alkaline fermentation tank, the outlet of the sludge alkaline fermentation tank is connected to the inlet of the sludge conditioning tank, the sludge conditioning tank is also connected to an acid dosing pipe, a coagulant dosing tank and a magnesium chloride dosing tank, the outlet of the sludge conditioning tank is connected to the inlet of a filter press, the outlet of the filter press is provided with a guide pipe, the guide pipe is connected to the anoxic tank, and the collected sludge alkaline fermentation liquid is used to supplement the carbon source required for denitrification in the anoxic tank.

[0008] Furthermore, a guide plate is provided in the middle of the anoxic pool, the angle between the guide plate and the wall surface is 10-20 degrees, and suspended biological fillers are arranged between the plates.

[0009] Furthermore, the suspended biological filler is made of high-density polyethylene, with a filler diameter of 10-25 mm, a filler height of 7-10 mm, and a density of 0.94-0.98 g / cm 3 , surface area>600m 2 / m 3 .

[0010] Furthermore, a composite filler is provided in the middle of the aerobic pool, and the specific surface area of ​​the composite filler is greater than 300m 2 / m 3 , density is 1.1-1.4g / cm 3 , diameter is 50-150mm.

[0011] Furthermore, a mechanical stirring device is provided in the sludge alkaline fermentation tank, and an alkali dosing tank is also connected to the inlet; the mechanical stirring device selects a 3-blade stirring paddle, the inclination angle of the stirring paddle is 30°, the ratio of the diameter to the tank diameter is 0.2-0.5, and the distance from the bottom of the tank body is not more than 20% of the height of the tank body.

[0012] Furthermore, a rapid agitator is provided in the sludge conditioning tank, and the rapid agitator adopts a 4-blade mechanical stirring paddle, the ratio of the diameter to the tank diameter is 0.6-0.8, the inclination angle of the blade root is 30-50°, the inclination angle of the blade top is 20-30°, and the distance from the bottom of the conditioning tank is not more than 10% of the tank body.

[0013] In a first aspect, the present invention provides a method for enhancing the biological treatment performance of sewage using sludge alkaline fermentation liquid, comprising the following steps:

[0014] S1: The sewage first passes through the screen and then enters the primary sedimentation tank. After being treated in the primary sedimentation tank, the sewage enters the anoxic tank, and the settled primary sludge enters the sludge mixing tank;

[0015] S2: After the sewage enters the anoxic tank, it is mixed with the nitrification liquid returned from the aerobic tank. At this time, the sludge alkaline fermentation liquid enters the anoxic tank as the carbon source required for denitrification;

[0016] S3: Then it enters the aerobic tank to further remove COD and ammonia nitrogen. The combined biological filler in the middle of the aerobic tank can enrich nitrifying bacteria with a longer period of time and improve the nitrification effect of the aerobic tank. Then the mud and water are separated in the secondary sedimentation tank to obtain effluent. Part of the remaining sludge is returned to the anoxic tank to ensure that the biological pool contains sufficient sludge concentration (3000-3800mg / L), and the rest of the remaining sludge enters the sludge mixing tank;

[0017] S4: The primary sludge and the residual sludge are mixed evenly in the sludge mixing tank and then enter the sludge alkaline fermentation tank. The pH in the sludge alkaline fermentation tank is adjusted, and the mechanical stirring device is stirred in an intermittent stirring manner to control the temperature and ferment the sludge;

[0018] S5: After fermentation is completed, the sludge mixture enters the sludge conditioning tank. At this time, the magnesium chloride dosing tank is opened to add magnesium chloride, and stirred at 200 rpm for 5 minutes. Then the acid dosing tank is opened to adjust the pH. Then the coagulant dosing tank is opened. After stirring at 200 rpm for 1 minute, the stirring speed is reduced to 100 rpm. After stirring for 10 minutes, stop and let it stand for 30 minutes.

[0019] S6: After being poured out from the sludge conditioning tank, it enters the filter press to complete the mud-water separation. The obtained sludge alkaline fermentation liquid is returned to the anoxic tank as a denitrification carbon source, and the sludge is discharged.

[0020] Furthermore, in step S2, the sludge alkaline fermentation liquid is derived from the liquid after filtration by the filter press, and the amount of the sludge alkaline fermentation liquid added is based on the influent COD and total nitrogen concentrations, so that the ratio of total COD to total nitrogen concentration is 7-9. The volatile fatty acids contained in the sludge alkaline fermentation liquid are high-quality carbon sources for biological denitrification, which can effectively improve the denitrification efficiency. At the same time, the various beneficial factors contained in the sludge alkaline fermentation liquid help to increase the diversity of microorganisms and the stability of sludge flocs. The suspended biological filler in the middle of the tank body can promote the colonization of denitrifying bacteria, increase the activity and total amount of denitrifying bacteria in the tank body, and ensure stable and efficient denitrification function.

[0021] Furthermore, in step S4, the pH in the sludge alkaline fermentation tank is adjusted to 10±0.3, and stirring is performed in an intermittent stirring manner, 4h 150rpm, 4h 0rpm every 8 hours, the sludge retention time is 6-9 days, and the temperature is controlled at 25-35°C. Under the premise of ensuring the dissolution and conversion of a large amount of sludge organic matter, this condition can promote the formation of microbial floc structure, enhance the activity of acid-producing functional microorganisms, and thereby produce a large amount of volatile fatty acids.

[0022] Furthermore, in step S5, the molar ratio of magnesium ions to phosphate in the sludge conditioning tank is 1.2-1.5:1, the pH is adjusted to 7.4-7.6, and then the coagulant dosing tank is opened to make the concentration of polyaluminium chloride 30-60 mg / L. Under this strategy, the removal effect of phosphate and difficult-to-biodegrade organic matter in the sludge alkaline fermentation liquid can be improved, the quality of the fermentation liquid can be improved, and the efficient denitrification process can be ensured; then it enters the filter press to complete the mud-water separation, and the obtained sludge alkaline fermentation liquid is returned to the anoxic tank as a denitrification carbon source, and the sludge is discharged.

[0023] Based on the above technical solution, the embodiments of the present invention can at least produce the following technical effects:

[0024] (1) The sludge alkaline fermentation tank of the present invention is provided with a three-blade mechanical stirring paddle. Under the intermittent stirring strategy, the continuous stirring stage can promote the uniform distribution of pH, sludge organic matter and microorganisms, and improve the hydrolysis effect of organic matter. The stopping stirring stage can promote the formation of microbial floc structure, thereby providing barrier protection for acid-producing functional bacteria, reducing the adverse effects of the alkaline environment on microorganisms, improving the activity of acid-producing functional microorganisms, promoting the conversion of soluble organic matter into volatile fatty acids, and ensuring efficient and stable acid production effect.

[0025] (2) The present invention is provided with a sludge conditioning tank. By adding magnesium chloride and a coagulant and adjusting the pH, it is possible to simultaneously achieve the effects of removing ammonia nitrogen, phosphate, and difficult-to-degrade organic matter in the fermentation liquid and improving the sludge dewatering performance, thereby improving the quality of the fermentation liquid and providing a high-quality carbon source for the denitrification process, reducing the adverse effects of using sludge alkaline fermentation liquid as a carbon source on the biological denitrification process, and reducing the utilization of commercial carbon sources.

[0026] (3) The anoxic tank of the present invention is provided with a suspended filler, and the aerobic tank is provided with a combined filler, which can effectively promote the enrichment of denitrifying bacteria and nitrifying bacteria, greatly improve the process denitrification efficiency, and improve the removal effect of organic matter in sewage. The device has low equipment requirements and is easy to operate. The method can effectively improve the efficiency and stability of sludge alkaline fermentation acid production, reduce the adverse effects on effluent water quality, have low energy consumption and low carbon emissions, and achieve the excellent effects of high efficiency, stability and low carbon emissions in the sewage biological treatment process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0028] Figure 1 It is a schematic diagram of the structure of the device of the present invention;

[0029] Among them, 1. screen; 2. primary sedimentation tank; 3. suspended filler; 4. anoxic tank; 5. combined filler; 6. aerobic tank; 7. secondary sedimentation tank; 8. sludge mixing tank; 9. alkali dosing tank; 10. sludge alkaline fermentation tank; 11. mechanical stirring device; 12. acid dosing tank; 13. coagulant dosing tank; 14. magnesium chloride dosing tank; 15. sludge conditioning tank; 16. rapid agitator; 17. filter press. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0031] Embodiment 1:

[0032] This example uses a small test device. The domestic sewage treated is taken from a municipal sewage treatment plant in Nanjing. The COD is 145-220 mg / L, NH4 + -N 25-32mg / L, total nitrogen concentration 31-39mg / L, PO4 3- -P 2.7-3.4mg / L. After the sewage is treated by the screen, it enters the primary sedimentation tank, where it settles for 1.5h, and then enters the anoxic tank. No sludge alkaline fermentation liquid was added during the first week of operation. Then, according to the ratio of influent COD to total nitrogen concentration, the ratio of COD to total nitrogen concentration was adjusted to 8 by adding sludge alkaline fermentation liquid. The angle between the guide plate and the wall in the anoxic tank was 15°. The suspended filler was made of high-density polyethylene, with a filler diameter of 25mm, a filler height of 10mm, and a density of 0.96g / cm 3 , specific surface area 680m 2 / m 3; Aerobic pool composite filler, select specific surface area 320m 2 / m 3 , density 1.3g / cm 3 , diameter 100mm. The sludge used is a mixture of primary sludge and residual sludge, with a sludge concentration of 21.7±0.4g / L, a total COD of 20.2±0.8g / L, a pH of 6.9-7.4, and a soluble COD of 317±46mg / L. The sludge alkaline fermentation tank is mechanically stirred, and a 3-blade stirring paddle is selected, with an inclination angle of 30°, a diameter-to-tank diameter ratio of 0.5, and a distance from the bottom of the tank body of 15% of the tank body height. The pH in the fermentation tank is adjusted to 10±0.3, and the agitator is stirred in an intermittent manner (4h 150rpm, 4h 150rpm every 8 hours). 0rpm) for stirring, the sludge retention time is 8 days, the temperature is controlled at 35°C, and after the reactor continues to operate for 15 days, the SCOD of the fermented liquid at the mud outlet can reach 7192±218mg / L, and the concentration of volatile fatty acids is 4169±208mgCOD / L, and the proportion of volatile fatty acids is relatively high; the fast agitator of the sludge conditioning tank adopts a 4-blade mechanical stirring paddle, the ratio of the diameter to the tank diameter is 0.8, the inclination angle of the blade root is 40°, the inclination angle of the blade top is 30°, and the distance from the bottom of the conditioning tank is 10% of the tank body , so that the molar ratio of magnesium ion to phosphate is 1.5:1, stir at 200 rpm for 5 minutes, adjust the pH to 7.5, the concentration of polyaluminium chloride is 50 mg / L, stir at 200 rpm for 1 minute, reduce the stirring speed to 100 rpm, stop stirring after 10 minutes, and let it stand for 30 minutes, and then enter the filter press to complete the mud and water separation, and the sludge alkaline fermentation liquid is returned to the anoxic tank as a denitrification carbon source; the denitrifying bacteria enriched in the anoxic tank use the easily degradable carbon source in the sludge alkaline fermentation liquid to reduce nitrate nitrogen to nitrogen gas. After the above device and method were operated for 45 days, the effluent COD was 30.5±3.8 mg / L, the TN concentration was 9.2±0.7 mg / L, and the NH4 + -N concentration 0.63±0.11mg / L.

[0033] Embodiment 2:

[0034] The difference from Example 1 is that the treated sewage is taken from a sewage treatment plant in a certain park, with COD 151-234 mg / L, NH4 + -N 34-41mg / L, total nitrogen concentration 42-54mg / L, PO4 3--P 4.3-5.1mg / L. After the sewage is treated by the screen, it enters the primary sedimentation tank. The sewage is settled in the primary sedimentation tank for 1.5h, and then enters the anoxic tank. No sludge alkaline fermentation liquid is added in the first week of operation. Then, according to the ratio of COD to total nitrogen concentration in the influent, the ratio of COD to total nitrogen concentration is adjusted to 7 by adding sludge alkaline fermentation liquid. The angle between the guide plate and the wall in the anoxic tank is 10°. The suspended filler is made of high-density polyethylene, with a filler diameter of 10mm, a filler height of 7mm, and a density of 0.94g / cm 3 , specific surface area 820m 2 / m 3 ; Aerobic pool composite filler, select specific surface area 380m 2 / m 3 , density 1.1g / cm 3 , diameter 50mm. The sludge used is a mixture of primary sludge and residual sludge, with a sludge concentration of 19.1±0.2g / L, a total sludge COD of 18.6±0.5g / L, a pH of 6.8-7.1, and a soluble COD of 278±44mg / L. The sludge alkaline fermentation tank is mechanically stirred, and a 3-blade stirring paddle is selected with an inclination angle of 30°, a diameter-to-tank diameter ratio of 0.3, and a distance from the bottom of the tank body of 10% of the tank body height. The pH in the fermentation tank is 10±0.3, and the agitator is stirred in an intermittent stirring mode (4h150rpm, 4h0rpm every 8 hours). The sludge retention time is 7 days, and the temperature is controlled at 30°C. After the reactor continues to run for 15d, the SCOD of the fermentation liquid at the mud outlet is 5929±221mg / L, and the concentration of volatile fatty acids is 3551±161mg COD / L; the rapid agitator of the sludge conditioning tank adopts a 4-blade mechanical stirring paddle, the ratio of the diameter to the tank diameter is 0.6, the inclination angle of the blade root is 50°, the inclination angle of the blade top is 20°, and the distance from the bottom of the conditioning tank is 10% of the tank body, so that the molar ratio of magnesium ion to phosphate is 1.3:1, stirring at 200 rpm for 5 minutes, adjusting the pH to 7.5, the concentration of polyaluminium chloride is 60 mg / L, stirring at 200 rpm for 1 minute, reducing the stirring speed to 100 rpm, stirring for 10 minutes and then stopping, and standing for 30 minutes, and then entering the filter press to complete the mud and water separation, and the sludge alkaline fermentation liquid is returned to the anoxic tank as a denitrification carbon source; the denitrifying bacteria enriched in the anoxic tank use the easily degradable carbon source in the sludge alkaline fermentation liquid to reduce nitrate nitrogen to nitrogen gas. After the above device and method were operated for 50 days, the effluent COD was 35.2±4.3mg / L, TN concentration was 11.2±0.8mg / L, NH4 + -N concentration 0.58±0.12mg / L.

[0035] Embodiment 3:

[0036] The difference from Example 1 is that the treated domestic sewage is taken from another municipal sewage treatment plant in Nanjing, with COD 131-184mg / L, NH4+-N 27-33mg / L, total nitrogen concentration 38-45mg / L, PO43--P 3.4-4.6mg / L. After the sewage is treated by the grid, it enters the primary sedimentation tank, and the primary sedimentation tank is settled for 1.5h, and then the sewage enters the anoxic tank. No sludge alkaline fermentation liquid is added in the first week of operation, and then the ratio of COD to total nitrogen concentration is adjusted to 9 by adding sludge alkaline fermentation liquid according to the ratio of influent COD to total nitrogen concentration. The angle between the guide plate and the wall in the anoxic tank is 10°, and the suspended filler is made of high-density polyethylene material, with a filler diameter of 25mm, a filler height of 10mm, and a density of 0.96g / cm 3 , specific surface area 680m 2 / m 3 ; Aerobic pool composite filler, select specific surface area 350m 2 / m 3 , density 1.4g / cm 3 , diameter 150mm. The sludge used is a mixture of primary sludge and residual sludge, with a sludge concentration of 16.3±0.3g / L, a total sludge COD of 15.2±0.6g / L, a pH of 6.9-7.3, and a soluble COD of 205±42mg / L. The sludge alkaline fermentation tank is mechanically stirred, and a 3-blade stirring paddle is selected with an inclination angle of 30°, a diameter-to-tank diameter ratio of 0.2, and a distance from the bottom of the tank body of 10% of the tank body height. The pH in the fermentation tank is adjusted to 10±0.3, and the agitator is stirred in an intermittent stirring mode (4h 150rpm, 4h 0rpm every 8 hours). The sludge retention time is 6 days, and the temperature is controlled at 25°C. After the reactor continues to run for 15 days, the SCOD of the fermentation liquid at the mud outlet is 4906±157mg / L, and the concentration of volatile fatty acids is 2955±198mg COD / L; the rapid agitator of the sludge conditioning tank adopts a 4-blade mechanical stirring paddle, the ratio of the diameter to the tank diameter is 0.7, the inclination angle of the blade root is 30°, the inclination angle of the blade top is 25°, and the distance from the bottom of the conditioning tank is 10% of the tank body, so that the molar ratio of magnesium ion to phosphate is 1.2:1, stirring at 200 rpm for 5 minutes, adjusting the pH to 7.4, the concentration of polyaluminium chloride is 30 mg / L, stirring at 200 rpm for 1 minute, reducing the stirring speed to 100 rpm, stirring for 10 minutes and then stopping, and standing for 30 minutes, and then entering the filter press to complete the mud and water separation, and the sludge alkaline fermentation liquid is returned to the anoxic tank as a denitrification carbon source; the denitrifying bacteria enriched in the anoxic tank use the easily degradable carbon source in the sludge alkaline fermentation liquid to reduce nitrate nitrogen to nitrogen gas. After the above device and method were operated for 30 days, the effluent COD was 31.9±2.1mg / L, TN concentration was 8.9±0.5mg / L, NH4 +-N concentration 0.71±0.18mg / L.

[0037] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of the present invention to be protected is defined by the attached claims and their equivalents.

Claims

1. A device for enhancing the biological treatment performance of sewage using sludge alkaline fermentation liquid, characterized in that: It comprises a grid (1), a primary sedimentation tank (2), an anoxic tank (4), an aerobic tank (6), a secondary sedimentation tank (7), a sludge mixing tank (8), a sludge alkaline fermentation tank (10), a sludge conditioning tank (15) and a filter press (17); wherein, The grille (1) is connected to a primary sedimentation tank (2); a first outlet of the primary sedimentation tank (2) is connected to an inlet of an anoxic tank (4); a second outlet of the primary sedimentation tank (2) is connected to an inlet of a sludge mixing tank (8); an outlet of the anoxic tank (4) is connected to an inlet of an aerobic tank (6); a first outlet of the aerobic tank (6) is connected to a secondary sedimentation tank (7); a second outlet of the aerobic tank (6) is connected to the anoxic tank (4); a first outlet of the secondary sedimentation tank (7) is connected to an external pipeline; and a second outlet of the secondary sedimentation tank (7) is connected to the anoxic tank (4) and the sludge mixing tank (8), respectively. The outlet of the sludge mixing tank (8) is connected to the inlet of the sludge alkaline fermentation tank (10), and the outlet of the sludge alkaline fermentation tank (10) is connected to the inlet of the sludge conditioning tank (15). The sludge conditioning tank (15) is also connected to an acid dosing tank (12), a coagulant dosing tank (13) and a magnesium chloride dosing tank (14). The outlet of the sludge conditioning tank (15) is connected to the inlet of a filter press (17). The outlet of the filter press (17) is provided with a guide pipe, which is connected to the anoxic tank (4). The collected sludge alkaline fermentation liquid is used to supplement the carbon source required for denitrification in the anoxic tank (4).

2. The device for enhancing the biological treatment performance of sewage by using sludge alkaline fermentation liquid according to claim 1, characterized in that: A guide plate is provided in the middle of the anoxic pool (4), the angle between the guide plate and the wall surface is 10-20 degrees, and suspended biological fillers (3) are provided between the plates.

3. The device for enhancing the biological treatment performance of sewage by using sludge alkaline fermentation liquid according to claim 2, characterized in that: The suspended biological filler (3) is made of high-density polyethylene, with a filler diameter of 10-25 mm, a filler height of 7-10 mm, and a density of 0.94-0.98 g / cm 3 , surface area>600m 2 / m 3 .

4. The device for enhancing the biological treatment performance of sewage by using sludge alkaline fermentation liquid according to claim 1, characterized in that: A composite filler (5) is provided in the middle of the aerobic pool (6), and the specific surface area of ​​the composite filler (5) is greater than 300 m 2 / m 3 , density is 1.1-1.4g / cm 3 , diameter is 50-150mm.

5. The device for enhancing the biological treatment performance of sewage by using sludge alkaline fermentation liquid according to claim 1, characterized in that: The sludge alkaline fermentation tank (10) is provided with a mechanical stirring device (11), and an alkali dosing tank (9) is also connected at the inlet; the mechanical stirring device (11) is a three-blade stirring paddle, the inclination angle of the stirring paddle is 30°, the ratio of the diameter to the tank diameter is 0.2-0.5, and the distance from the bottom of the tank body (3) is not greater than 20% of the height of the tank body.

6. The device for enhancing the biological treatment performance of sewage by using sludge alkaline fermentation liquid according to claim 1, characterized in that: The sludge conditioning tank (15) is provided with a rapid agitator (16), which adopts a 4-blade mechanical stirring paddle, the ratio of the diameter to the tank diameter is 0.6-0.8, the inclination angle of the blade root is 30-50°, the inclination angle of the blade top is 20-30°, and the distance from the bottom of the conditioning tank (8) is not more than 10% of the tank body.

7. A method for enhancing the biological treatment performance of sewage by using sludge alkaline fermentation liquid, using the device for enhancing the biological treatment performance of sewage by using sludge alkaline fermentation liquid according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: The sewage first passes through the screen (1) and then enters the primary sedimentation tank (2). After being treated in the primary sedimentation tank, the sewage enters the anoxic tank (4), and the settled primary sludge enters the sludge mixing tank (8); S2: After the sewage enters the anoxic tank (4), it is mixed with the nitrification liquid returned from the aerobic tank (6). At this time, the sludge alkaline fermentation liquid enters the anoxic tank (4) as the carbon source required for denitrification; S3: Then it enters the aerobic tank (6) to further remove COD and ammonia nitrogen, and then completes the mud-water separation in the secondary sedimentation tank (7) to obtain effluent. Part of the remaining sludge is returned to the anoxic tank (4) to ensure that the biological tank contains sufficient sludge concentration, and the remaining remaining sludge enters the sludge mixing tank (8); S4: the primary sludge and the residual sludge are mixed evenly in the sludge mixing tank (8) and then enter the sludge alkaline fermentation tank (10), the pH in the sludge alkaline fermentation tank (10) is adjusted, and the mechanical stirring device (11) stirs in an intermittent stirring manner to control the temperature and ferment the sludge; S5: After fermentation is completed, the sludge mixture enters the sludge conditioning tank (15). At this time, the magnesium chloride dosing tank (14) is opened to add magnesium chloride, and stirred at 200 rpm for 5 minutes. Then, the acid dosing tank (12) is opened to adjust the pH. Then, the coagulant dosing tank (13) is opened, and after stirring at 200 rpm for 1 minute, the stirring speed is reduced to 100 rpm, and the stirring is stopped after 10 minutes, and the mixture is allowed to stand for 30 minutes. S6: After coming out of the sludge conditioning tank (15), it enters the filter press (17) to complete the separation of mud and water. The obtained sludge alkaline fermentation liquid is returned to the anoxic tank (4) as a denitrification carbon source, and the sludge is discharged.

8. The method for enhancing the performance of sewage biological treatment by using sludge alkaline fermentation liquid according to claim 7, characterized in that: In step S2, the sludge alkaline fermentation liquid comes from the liquid filtered by the filter press (17), and the dosage of the sludge alkaline fermentation liquid is based on the influent COD and total nitrogen concentrations so that the ratio of total COD to total nitrogen concentration is 7-9.

9. The method for enhancing the performance of sewage biological treatment by using sludge alkaline fermentation liquid according to claim 7, characterized in that: In step S4, the pH in the sludge alkaline fermentation tank (10) is adjusted to 10±0.3, and stirring is performed in an intermittent stirring manner, 4 hours at 150rpm and 4 hours at 0rpm every 8 hours, the sludge retention time is 6-9 days, and the temperature is controlled at 25-35°C.

10. The method for enhancing the performance of sewage biological treatment by using sludge alkaline fermentation liquid according to claim 7, characterized in that: In step S5, the molar ratio of magnesium ion to phosphate in the sludge conditioning tank (15) is 1.2-1.5:1, the pH is adjusted to 7.4-7.6, and then the coagulant dosing tank (13) is opened to make the concentration of polyaluminium chloride 30-60 mg / L.

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