A device and method for enhancing the performance of sewage biological treatment by using sludge alkaline fermentation liquid

Abstract

The application discloses a device and method for enhancing sewage biological treatment performance by using sludge alkaline fermentation liquid, and solves the technical problems of high energy consumption and complex operation in the prior art. The device comprises a grid, 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. The middle part of the anoxic tank is provided with a flow guide plate, and suspended biological fillers are arranged between the plates. The middle part of the aerobic tank is provided with combined fillers. 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 application can effectively improve the sewage treatment performance, improve the total nitrogen removal rate, improve the treatment load of the anoxic tank, enhance the operation stability of the sewage treatment system, reduce the dosage of the added carbon source, reduce the sludge volume and reduce the carbon emission of the sewage plant.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage and sludge treatment, and particularly relates to a device and method for enhancing the performance of sewage biological treatment by using sludge alkaline fermentation liquid. BACKGROUND

[0002] Stable and efficient removal of total nitrogen in sewage is an important task for municipal sewage treatment plants. The low carbon-nitrogen ratio of the influent in China's municipal sewage treatment plants leads to poor denitrification effect. Sewage plants often add sodium acetate and other carbon sources to achieve efficient denitrification, but this significantly increases the operating cost of municipal sewage treatment plants, which is not conducive to the carbon neutral operation of sewage plants. Finding an economic and efficient carbon source is an urgent demand for sewage treatment plants, and it has important practical significance for stable and efficient removal of total nitrogen in sewage. Sewage biological treatment is accompanied by the generation of a large amount of excess sludge, and alkaline fermentation can effectively promote the hydrolysis and acidification of excess sludge and accumulate high concentrations of volatile fatty acids in the fermentation liquid. Using sludge alkaline fermentation liquid (SAFL) as a biological denitrification carbon source can effectively improve the total nitrogen removal efficiency, and can also promote sludge reduction and resource utilization, which is conducive to the carbon neutral operation of sewage plants.

[0003] However, due to the inhibition of the activity of acid-producing functional microorganisms under alkaline conditions, a large amount of dissolved organic matter in the SAFL is not converted into volatile fatty acids, which limits the improvement of the quality of sludge alkaline fermentation liquid. On the other hand, SAFL also contains a large amount of humic acid and other refractory organic matter, which will cause the increase of dissolved organic matter (DOM) in the effluent of the biological denitrification process when used as a carbon source. DOM is a key factor affecting the quality of the effluent of sewage plants, and is also a major factor restricting the advanced treatment and reuse of secondary effluent. As a precursor of disinfection by-products, it will increase the environmental risk of effluent discharge into natural water bodies. Therefore, it is urgent to explore the technology for enhancing the production of volatile fatty acids by sludge alkaline fermentation microorganisms and to find a method for controlling the DOM in the effluent of the biological denitrification process when using SAFL as a carbon source.

[0004] The researchers at home and abroad study the method for improving the acid production of sludge alkaline fermentation, mainly including pretreatment technology, pH gradient control method, etc. The pretreatment technology mainly improves the hydrolysis efficiency of sludge through high temperature, high ferrate and other means, and then promotes the acid production; the pH gradient control method mainly controls the pH in the fermentation process step by step, first promotes the sludge hydrolysis through a higher pH, and then reduces the pH to promote the enrichment and activity improvement of the hydrolysis acidification bacteria. These methods can effectively improve the sludge hydrolysis acidification effect, but these methods often have problems of high energy consumption, complex operation, etc., which limit the application of these technical methods. In addition, at present, there are few reports on the control method of DOM in the effluent of the biological denitrification process when SAFL is used as a carbon source. The above problems greatly limit the application of sludge alkaline fermentation liquid to promote the biological treatment of wastewater, so it is of great practical significance to explore the measures for efficiently strengthening the performance of wastewater biological treatment by using sludge alkaline fermentation liquid. SUMMARY

[0005] The technical problem solved by the present application is that: in view of the problems that a large amount of dissolved organic matter is not converted into volatile fatty acids in the sludge alkaline fermentation process, which limits the improvement of the quality of sludge alkaline fermentation liquid, and the SAFL contains a large amount of humic acid and other refractory organic matter, which leads to the increase of DOM in the effluent of the biological denitrification process when the SAFL is used as a carbon source, a process device and method for efficiently strengthening the performance of wastewater biological treatment by using sludge alkaline fermentation liquid are provided, which can effectively reduce the DOM in the effluent of the biological denitrification process when the SAFL is used as a carbon source on the basis of ensuring the improvement of the performance of sludge alkaline fermentation for producing volatile fatty acids, has good denitrification effect, high sludge resource utilization efficiency, low energy consumption, convenient operation and management, stable process operation.

[0006] To achieve the above object, the present application provides the following technical scheme:

[0007] In a first aspect, the present application provides a device for enhancing the performance of sewage biological treatment by using sludge alkaline fermentation liquid, comprising a grid, 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 grid is connected with the primary sedimentation tank, the first outlet of the primary sedimentation tank is communicated with the inlet of the anoxic tank, the second outlet of the primary sedimentation tank is communicated with the inlet of the sludge mixing tank, the outlet of the anoxic tank is communicated with the inlet of the aerobic tank, the first outlet of the aerobic tank is communicated with the secondary sedimentation tank, the second outlet of the aerobic tank is communicated with the anoxic tank, the first outlet of the secondary sedimentation tank is communicated with an external pipeline, the second outlet of the secondary sedimentation tank is respectively communicated with the anoxic tank and the sludge mixing tank, the outlet of the sludge mixing tank is communicated with the inlet of the sludge alkaline fermentation tank, the outlet of the sludge alkaline fermentation tank is communicated with the inlet of the sludge conditioning tank, the sludge conditioning tank is further connected with an acid dosing pipe, a coagulant dosing tank and a magnesium chloride dosing tank, the outlet of the sludge conditioning tank is communicated with the inlet of the filter press, the outlet of the filter press is provided with a flow guide pipe, and the flow guide pipe is connected with the anoxic tank.

[0008] Further, the middle part of the anoxic tank is provided with a flow guide plate, the included angle between the flow guide plate and the wall surface is 10-20°, and suspended biological fillers are arranged between the plates.

[0009] Further, the suspended biological fillers are made of high-density polyethylene material, the diameter of the fillers is 10-25 mm, the height of the fillers is 7-10 mm, and the density is 0.94-0.98 g / cm 3 , and the specific surface area is >600 m 2 / m 3 .

[0010] Further, the middle part of the aerobic tank is provided with combined fillers, the specific surface area of the combined fillers is >300 m 2 / m 3 , the density is 1.1-1.4 g / cm 3 , and the diameter is 50-150 mm.

[0011] Further, the sludge alkaline fermentation tank is provided with a mechanical stirring device, and an alkali dosing tank is further connected with 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 of the sludge alkaline fermentation tank is not greater than 20% of the height of the tank body.

[0012] Further, the sludge conditioning tank is provided with a rapid stirrer, the rapid stirrer 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 sludge conditioning tank is not greater than 10% of the tank body.

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

[0014] S1: The sewage first passes through a grid, and then enters a primary sedimentation tank. After treatment by the primary sedimentation tank, the sewage enters an anoxic tank, and the primary sludge precipitated in the primary sedimentation tank enters a sludge mixing tank;

[0015] S2: After the sewage enters the anoxic tank, it is mixed with the nitrification liquid refluxed 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 the nitrifying bacteria with a long generation cycle, improve the nitrification effect of the aerobic tank, and then complete the separation of sludge and water in the secondary sedimentation tank to obtain effluent. Part of the remaining sludge is refluxed to the anoxic tank to ensure that the biological tank contains sufficient sludge concentration (3000-3800 mg / L). The rest of the remaining sludge enters the sludge mixing tank;

[0017] S4: After the primary sludge and the remaining sludge are uniformly mixed in the sludge mixing tank, they enter the sludge alkaline fermentation tank. The pH in the sludge alkaline fermentation tank is adjusted, the mechanical stirring device is stirred in an intermittent stirring manner, and the temperature is controlled to ferment the sludge;

[0018] S5: After fermentation is completed, the sludge mixture enters the sludge conditioning tank. At this time, magnesium chloride is added by opening the magnesium chloride dosing tank, stirring at 200 rpm for 5 min, then adjusting the pH by opening the acid dosing tank, and then opening the coagulant dosing tank. After stirring at 200 rpm for 1 min, the stirring speed is reduced to 100 rpm. After stirring for 10 min, stop and stand for 30 min;

[0019] S6: After coming out of the sludge conditioning tank, it enters the filter press to complete the separation of sludge and water, and the obtained sludge alkaline fermentation liquid is refluxed to the anoxic tank as the denitrification carbon source. The sludge is discharged.

[0020] Further, in step S2, the sludge alkaline fermentation liquid is derived from the liquid after pressure filtration of the filter press. The dosage of the sludge alkaline fermentation liquid is determined according to the concentrations of the influent COD and total nitrogen, 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 efficiently 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 can promote the colonization of denitrifying bacteria, improve the activity and total amount of denitrifying bacteria in the tank, 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. Every 8 hours, 4 hours are at 150rpm and 4 hours are at 0rpm. 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 thus 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 polyaluminum chloride concentration 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 produce at least 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 can 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 equipped with suspended biological fillers, and the aerobic tank is equipped with composite fillers, 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, and has low energy consumption and low carbon emissions, achieving the excellent results of efficient, stable and low carbon emissions in the sewage biological treatment process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only show some of the embodiments of the present application, and all other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

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

[0029] In the figure, 1 is a grid, 2 is a primary sedimentation tank, 3 is suspended biological filler, 4 is an anoxic tank, 5 is a combined filler, 6 is an aerobic tank, 7 is a secondary sedimentation tank, 8 is a sludge mixing tank, 9 is an alkali dosing tank, 10 is a sludge alkali fermentation tank, 11 is a mechanical stirring device, 12 is an acid dosing tank, 13 is a coagulant dosing tank, 14 is a magnesium chloride dosing tank, 15 is a sludge conditioning tank, 16 is a rapid stirrer, and 17 is a filter press. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort belong to the protection scope of the present application. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the fact that those skilled in the art can realize it. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist and is not within the protection scope of the present application.

[0031] Embodiment 1

[0032] In this embodiment, a small-scale experimental device is used, and the domestic sewage treated is taken from a municipal sewage treatment plant in Nanjing, with COD of 145-220 mg / L, NH4 + -N of 25-32 mg / L, total nitrogen concentration of 31-39 mg / L, and PO4 3- -P of 2.7-3.4 mg / L. After the sewage is treated by the grid, it enters the primary sedimentation tank, and is deposited for 1.5 h. Then, the sewage enters the anoxic tank. In the first week of operation, no sludge alkali fermentation liquid is added. Then, according to the ratio of the COD and total nitrogen concentration of the influent, the ratio of the COD and total nitrogen concentration is adjusted to 8 by adding the sludge alkali fermentation liquid. The included angle between the guide plate and the wall surface in the anoxic tank is 15°. The suspended biological filler is made of high-density polyethylene material, with a filler diameter of 25 mm, a filler height of 10 mm, and a specific gravity of 0.96 g / cm 3 . The specific surface area is 680 m 2 / m 3; aerobic tank combined packing, specific surface area 320 m 2 / m 3 , density 1.3 g / cm 3 , diameter 100 mm. The sludge used was a mixture of primary sludge and excess sludge, with a sludge concentration of 21.7 ± 0.4 g / L, a total COD of 20.2 ± 0.8 g / L, a pH of 6.9-7.4, and a soluble COD of 317 ± 46 mg / L. The sludge alkaline fermentation tank was mechanically stirred, with a selection of 3-blade stirring paddles, an angle of inclination of 30°, a ratio of diameter to tank diameter of 0.5, a distance from the bottom of the tank of 15% of the height of the tank, a pH in the fermentation tank of 10 ± 0.3, and a stirrer that was stirred in an intermittent manner (4 h at 150 rpm and 4 h at 0 rpm every 8 h), with a sludge retention time of 8 days, and a temperature of 35°C. After the reactor was operated for 15 d, the fermented sludge at the sludge outlet had a SCOD of 7192 ± 218 mg / L, a volatile fatty acid concentration of 4169 ± 208 mg COD / L, and a high volatile fatty acid proportion. The rapid stirrer of the sludge conditioning tank used 4-blade mechanical stirring paddles, with a ratio of diameter to tank diameter of 0.8, an angle of inclination of 40° at the root of the blade, an angle of inclination of 30° at the top of the blade, a distance from the bottom of the conditioning tank of 10% of the height of the tank, a molar ratio of magnesium ions to phosphate radicals of 1.5:1, stirring at 200 rpm for 5 min, adjusting the pH to 7.5, a polyaluminum chloride concentration of 50 mg / L, stirring at 200 rpm for 1 min, then reducing the stirring speed to 100 rpm, stopping after stirring for 10 min, and then standing for 30 min, before entering the filter press to complete the separation of sludge and water, and the sludge alkaline fermentation liquid was returned to the anoxic tank as a denitrification carbon source. The denitrifying bacteria enriched in the anoxic tank reduced nitrate nitrogen to nitrogen gas using the easily degradable carbon source in the sludge alkaline fermentation liquid. After the above device and method were operated for 45 d, 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 was 0.63 ± 0.11 mg / L.

[0033] Example 2:

[0034] The difference between Example 1 and Example 2 is that the wastewater treated was taken from a park wastewater treatment plant, with a COD of 151-234 mg / L, an NH4 + -N concentration of 34-41 mg / L, and a total nitrogen concentration of 42-54 mg / L, and a PO4 3-P 4.3-5.1 mg / L. The sewage was treated by a grid and then entered a primary sedimentation tank, which was settled for 1.5 h, and then the sewage entered an anoxic tank. In the first week, no sludge alkaline fermentation liquid was added. Then, according to the ratio of the concentrations of COD and total nitrogen in the influent, the ratio of the concentrations of COD and total nitrogen was adjusted to 7 by adding sludge alkaline fermentation liquid. The angle between the guide plate and the wall surface in the anoxic tank was 10°. The suspended biological filler was made of high-density polyethylene material, with a filler diameter of 10 mm, a filler height of 7 mm, and a density of 0.94 g / cm 3 ; the specific surface area was 820 m 2 / g 3 ; the specific surface area of the combined filler in the aerobic tank was 380 m 2 / g 3 , the density was 1.1 g / cm 3 , and the diameter was 50 mm. The sludge used was a mixture of primary sludge and excess sludge, with a sludge concentration of 19.1 ± 0.2 g / L, a total sludge COD of 18.6 ± 0.5 g / L, a pH of 6.8-7.1, and a dissolved COD of 278 ± 44 mg / L. The sludge alkaline fermentation tank was mechanically stirred, with 3 stirring blades at an inclination angle of 30°, a ratio of the diameter to the tank diameter of 0.3, and a distance from the bottom of the tank to the tank height of 10%. The pH in the fermentation tank was 10 ± 0.3. The stirrer was stirred in an intermittent stirring mode (4 h at 150 rpm and 4 h at 0 rpm every 8 hours), with a sludge retention time of 7 days and a controlled temperature of 30°C. After the reactor was continuously operated for 15 days, the fermentation liquid SCOD at the sludge outlet was 5929 ± 221 mg / L, and the volatile fatty acid concentration was 3551 ± 161 mg COD / L. The rapid stirrer of the sludge conditioning tank used 4-blade mechanical stirring blades, with a ratio of the diameter to the tank diameter of 0.6, a blade root inclination angle of 50°, a blade top inclination angle of 20°, and a distance from the bottom of the conditioning tank to the tank of 10%. The molar ratio of magnesium ions to phosphate was 1.3:1, the stirring was performed at 200 rpm for 5 min, the pH was adjusted to 7.5, the polyaluminum chloride concentration was 60 mg / L, the stirring was performed at 200 rpm for 1 min, then the stirring speed was reduced to 100 rpm, the stirring was stopped after 10 min, and the system was allowed to stand for 30 min. Then, the sludge water separation was completed in a filter press, and the sludge alkaline fermentation liquid was returned to the anoxic tank as a denitrification carbon source. The enriched denitrifying bacteria in the anoxic tank reduced nitrate nitrogen to nitrogen gas using the easily degradable carbon source in the sludge alkaline fermentation liquid. After the above device and method were operated for 50 days, the effluent COD was 35.2 ± 4.3 mg / L, the TN concentration was 11.2 ± 0.8 mg / L, the NH4 + -N concentration was 0.58 ± 0.12 mg / L.

[0035] Example 3:

[0036] The domestic sewage was taken from another municipal sewage treatment plant in Nanjing, and the COD, NH4+-N, total nitrogen and PO43--P concentrations were 131-184 mg / L, 27-33 mg / L, 38-45 mg / L and 3.4-4.6 mg / L, respectively. The sewage was treated by a grid and then entered an initial sedimentation tank for 1.5 h. Then the sewage entered an anoxic tank. In the first week, no sludge alkaline fermentation liquid was added. Then, according to the ratio of the COD to the total nitrogen concentration in the influent, the ratio of the COD to the total nitrogen concentration was adjusted to 9 by adding the sludge alkaline fermentation liquid. The angle between the guide plate and the wall surface in the anoxic tank was 10°. The suspended biological filler was made of high-density polyethylene material, and the filler diameter was 25 mm and the filler height was 10 mm. The density was 0.96 g / cm3. The specific surface area was 680 m2 / g. The filler in the aerobic tank was combined, and the specific surface area was 350 m2 / g, the density was 1.4 g / cm3, and the diameter was 150 mm. The sludge used was a mixture of the primary sludge and the excess sludge, and the sludge concentration was 16.3±0.3 g / L. The total COD of the sludge was 15.2±0.6 g / L, the pH was 6.9-7.3, and the soluble COD was 205±42 mg / L. The sludge alkaline fermentation tank was mechanically stirred, and the stirring paddle had three leaves with an inclination angle of 30°. The ratio of the diameter to the tank diameter was 0.2, and the distance from the paddle to the bottom of the tank was 10% of the height of the tank. The pH in the fermentation tank was 10±0.3. The stirrer was stirred in an intermittent manner (4 h at 150 rpm and 4 h at 0 rpm in every 8 h). The sludge retention time was 6 days, and the temperature was controlled at 25°C. After the reactor was continuously operated for 15 days, the SCOD of the fermentation liquid at the sludge outlet was 4906±157 mg / L, and the volatile fatty acid concentration was 2955±198 mg COD / L. The fast stirrer of the sludge conditioning tank used a mechanical stirring paddle with four leaves. The ratio of the diameter to the tank diameter was 0.7. The inclination angle of the root of the leaf was 30°, and the inclination angle of the top of the leaf was 25°. The distance from the leaf to the bottom of the conditioning tank was 10% of the height of the tank. The molar ratio of the magnesium ion to the phosphate was 1.2:1. The stirring was performed at 200 rpm for 5 min. The pH was adjusted to 7.4. The polyaluminum chloride concentration was 30 mg / L. After stirring at 200 rpm for 1 min, the stirring speed was reduced to 100 rpm. After stirring for 10 min, the stirring was stopped and the sludge was allowed to stand for 30 min. Then the sludge was introduced into a filter press to complete the separation of the sludge and the water. The sludge alkaline fermentation liquid was returned to the anoxic tank as a denitrification carbon source. The denitrifying bacteria enriched in the anoxic tank reduced the nitrate nitrogen to nitrogen gas by using the easily degradable carbon source in the sludge alkaline fermentation liquid. 3 2 3 2 3 3 + ​​​​​​- N concentration 0.71 ± 0.18 mg / L.

[0037] The above shows and describes the basic principles and main features of the present application and the advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for enhancing the performance of a sewage biological treatment using sludge alkaline fermentation broth, the method being used in an apparatus for enhancing the performance of a sewage biological treatment using sludge alkaline fermentation broth, characterized by, The device 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 grid (1) is connected with the primary sedimentation tank (2), the first outlet of the primary sedimentation tank (2) is communicated with the inlet of the anoxic tank (4), the second outlet of the primary sedimentation tank (2) is communicated with the inlet of the sludge mixing tank (8), the outlet of the anoxic tank (4) is communicated with the inlet of the aerobic tank (6), the first outlet of the aerobic tank (6) is communicated with the secondary sedimentation tank (7), the second outlet of the aerobic tank (6) is communicated with the anoxic tank (4), the first outlet of the secondary sedimentation tank (7) is communicated with an external pipeline, the second outlet of the secondary sedimentation tank (7) is respectively communicated with the anoxic tank (4) and the sludge mixing tank (8), the outlet of the sludge mixing tank (8) is communicated with the inlet of the sludge alkaline fermentation tank (10), the outlet of the sludge alkaline fermentation tank (10) is communicated with the inlet of the sludge conditioning tank (15), the sludge conditioning tank (15) is further connected with 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 communicated with the inlet of the filter press (17), the outlet of the filter press (17) is provided with a flow guide pipe, the flow guide pipe is connected with the anoxic tank (4), and the collected sludge alkaline fermentation liquid is used to supplement the carbon source required for denitrification of the anoxic tank (4); The mechanical stirring device (11) is arranged in the sludge alkaline fermentation tank (10), and the inlet is further connected with an alkali dosing tank (9); the mechanical stirring device (11) 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 stirring paddle to the bottom of the tank body of the sludge alkaline fermentation tank (10) is not greater than 20% of the height of the tank body; The method comprises the following steps: S1: sewage first passes through the grid (1), and then enters the primary sedimentation tank (2), after being treated by the primary sedimentation tank, the sewage enters the anoxic tank (4), and the primary sludge precipitated is introduced into the sludge mixing tank (8); S2: after the sewage enters the anoxic tank (4), the sewage is mixed with the nitrification liquid refluxed 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, the sewage enters the aerobic tank (6) to further remove COD and ammonia nitrogen, and then the sludge-water separation is completed in the secondary sedimentation tank (7) to obtain effluent, part of the residual sludge is refluxed to the anoxic tank (4) to ensure that the biological tank contains sufficient sludge concentration, and the remaining residual sludge enters the sludge mixing tank (8); S4: after the primary sludge and the residual sludge are uniformly mixed in the sludge mixing tank (8), the sludge enters the sludge alkaline fermentation tank (10), the pH in the sludge alkaline fermentation tank (10) is adjusted, the mechanical stirring device (11) is stirred in an intermittent stirring mode, the temperature is controlled, and the sludge is fermented. The pH in the sludge alkaline fermentation tank (10) is adjusted to 10±0.3, and stirring is carried out in an intermittent stirring manner, 4h 150rpm and 4h 0rpm in every 8 hours, the sludge retention time is 6-9 days, and the temperature is controlled at 25-35℃; S5: After the fermentation is completed, the sludge mixed solution enters the sludge conditioning tank (15), at this time, the magnesium chloride dosing tank (14) is opened to add magnesium chloride, 200rmp is stirred for 5min, then the acid dosing tank (12) is opened to adjust the pH, and then the coagulant dosing tank (13) is opened, 200rpm is stirred for 1min, then the stirring speed is reduced to 100rmp, stirring is stopped after 10min, and standing is carried out for 30min; The molar ratio of magnesium ions to phosphate radicals 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, so that the polyaluminum chloride concentration is 30-60mg / L; S6: After coming out of the sludge conditioning tank (15), it enters the filter press (17) to complete the separation of sludge and water, and the obtained sludge alkaline fermentation liquid is used as a denitrification carbon source and is returned to the anoxic tank (4), and sludge is discharged.

2. The method according to claim 1, wherein the method is characterized by, The middle part of the anoxic tank (4) is provided with a guide plate, the included angle between the guide plate and the wall surface is 10-20°, and the suspended biological filler (3) is arranged between the plates.

3. The method according to claim 2, wherein the method is characterized by, The suspended biological filler (3) is made of high-density polyethylene, the diameter of the filler is 10-25 mm, the height of the filler is 7-10 mm, and the density is 0.94-0.98 g / cm 3 . The specific surface area is >600 m 2 / g 3 .

4. The method according to claim 1, wherein the method is characterized by, The aerobic tank (6) is provided with a combined filler (5) in the middle part, the specific surface area of the combined filler (5) is >300m 2 / m 3 , the density is 1.1-1.4g / cm 3 , and the diameter is 50-150mm.

5. The method according to claim 1, wherein the method is characterized by, The sludge conditioning tank (15) is provided with a rapid stirrer (16), the rapid stirrer (16) adopts a 4-blade mechanical stirring paddle, the ratio of the diameter to the tank diameter is 0.6-0.8, the blade root inclination angle is 30-50°, the blade top inclination angle is 20-30°, and the distance from the bottom of the sludge conditioning tank (15) is not more than 10% of the tank body.

6. The method according to claim 1, wherein the method is characterized by, In step S2, the sludge alkaline fermentation liquid is derived from the liquid after filtration of the filter press (17), and the dosing amount of the sludge alkaline fermentation liquid is determined according to the influent COD and total nitrogen concentration, so that the ratio of total COD to total nitrogen concentration is 7-9.

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