Device and method for realizing deep denitrification and sludge reduction by continuous flow a / o in-situ hydrolysis acidification coupled with short-cut denitrification and anaerobic ammonia oxidation

Abstract

The device and method for realizing deep denitrification and sludge reduction by continuous flow A / O in-situ hydrolysis acidification coupled with short-cut denitrification and anaerobic ammonia oxidation belong to the field of sewage treatment technology. The device is sequentially connected by a sewage tank (1), a sludge storage tank (2), an anoxic biochemical tank (5), a sedimentation tank (8) and an aerobic biochemical tank (12). In the anoxic biochemical tank (5), the residual sludge is subjected to in-situ hydrolysis acidification to be converted into small-molecule organic matter; the short-cut denitrifying bacteria utilize the easily degradable organic matter in the sewage and the hydrolysis acidification to convert nitrate into nitrite; meanwhile, the anaerobic ammonia oxidation bacteria utilize the nitrite to directly oxidize the ammonia nitrogen in the sewage into nitrogen, thereby realizing the in-situ hydrolysis coupling short-cut denitrification and anaerobic ammonia oxidation process. In the aerobic biochemical tank (12), only the filler biofilm is present, which can advantageously enrich the nitrifying bacteria and efficiently perform nitrification. The method realizes deep denitrification of low-COD / N sewage while reducing the sludge, and significantly saves energy and reduces consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to a device and method for realizing deep denitrification and sludge reduction by continuous flow A / O in-situ hydrolysis acidification coupled with short-cut denitrification anaerobic ammonia oxidation, and belongs to the technical field of biological wastewater treatment, which is widely applicable to municipal wastewater treatment plants with low COD / N. BACKGROUND

[0002] In most areas of China, the organic matter concentration of the influent in municipal wastewater treatment is generally low, which cannot meet the demand for denitrification. Therefore, in the face of increasingly stringent wastewater discharge standards, wastewater treatment plants have to add additional carbon sources to complete the denitrification requirement. On the one hand, this greatly increases the operating cost of the wastewater treatment plant; and the addition of a large amount of carbon source also causes an increase in the production of excess sludge, and the difficulty and cost of sludge treatment and disposal also increase.

[0003] As an autotrophic denitrification technology, anaerobic ammonia oxidation can directly utilize nitrite to oxidize ammonia nitrogen to nitrogen, without the need for additional carbon source, thereby greatly saving aeration energy consumption and reducing sludge production. Short-cut denitrification reduces nitrate to nitrite, which can provide an important substrate for the anaerobic ammonia oxidation process. Compared with short-cut nitrification, this technology is more stable and easy to control, and is particularly suitable for low COD / N municipal wastewater treatment. Therefore, the application of short-cut denitrification anaerobic ammonia oxidation technology to wastewater treatment plants not only eliminates the dependence on carbon source, but also reduces sludge production.

[0004] The treatment and disposal of excess sludge has become a key problem that cannot be ignored in the operation of wastewater treatment plants, and wastewater treatment generally exists the phenomenon of "paying more attention to water and less attention to sludge". At present, the treatment of sludge mostly needs additional anaerobic digestion facilities, which not only increases the investment and operating cost, but also many wastewater treatment plants do not reserve land, which makes it difficult to implement. If the excess sludge can be hydrolyzed and acidified in-situ in the biochemical tank, not only the sludge treatment problem can be solved, but also carbon source can be provided for the denitrification process, which can solve the problems of denitrification and sludge treatment at the same time.

[0005] In summary, the present method combines in-situ hydrolysis acidification with short-cut denitrification anaerobic ammonia oxidation in the continuous flow treatment system widely used in wastewater treatment plants, in order to realize deep denitrification and sludge reduction of low COD / N municipal wastewater. SUMMARY

[0006] The application aims to provide a device and method for realizing deep denitrification and sludge reduction by continuous flow A / O in-situ hydrolysis acidification coupled with short-cut denitrification and anaerobic ammonia oxidation. The specific principle is as follows: wastewater and residual sludge enter an anoxic biochemical tank according to a certain proportion, and backflow sludge and backflow nitrated liquid also enter at the same time. In the anoxic biochemical tank, fermenting functional bacteria can hydrolyze and acidify the difficult-to-biodegrade organic matter in raw water and residual sludge, and convert them into small-molecule biodegradable organic matter, thereby realizing sludge reduction while producing carbon source. Short-cut denitrification bacteria utilize the biodegradable organic matter in raw water and produced in the hydrolysis acidification process to perform short-cut denitrification to convert nitrate into nitrite. Anaerobic ammonia oxidation bacteria on the biofilm utilize the nitrite produced in the short-cut denitrification process to directly oxidize the ammonia nitrogen in raw water and produced in the hydrolysis acidification process into nitrogen. The whole process realizes on-site production and use of carbon source and nitrite, and realizes the synergistic effect of fermenting functional bacteria, short-cut denitrification bacteria and anaerobic ammonia oxidation bacteria. The sludge-water mixture is separated in a sedimentation tank, and the supernatant enters a subsequent pure biofilm aerobic biochemical tank to complete nitrification of residual ammonia nitrogen and further removal of residual organic matter. The aerobic biochemical tank adopts a pure biofilm system, which can advantageously enrich nitrifying bacteria and has high nitrification efficiency.

[0007] The device for realizing deep denitrification and sludge reduction by continuous flow A / O in-situ hydrolysis acidification coupled with short-cut denitrification and anaerobic ammonia oxidation is characterized by comprising a sewage tank (1), a sludge storage tank (2), an anoxic biochemical tank (5), a sedimentation tank (8), an aerobic biochemical tank (12) and a PLC control system (19). Sewage and residual sludge enter the first compartment of the anoxic biochemical tank (5) through a sewage pump (3) and a sludge pump (4) respectively, and at the same time, return sludge from the sedimentation tank (8) pumped by a sludge return pump (9) and return nitrification liquid from the aerobic biochemical tank (12) pumped by a nitrification liquid return pump (17) also enter the first compartment. The sludge-water mixture sequentially passes through the subsequent compartments of the anoxic biochemical tank (5) and then enters the sedimentation tank (8) for sludge-water separation, the supernatant enters the intermediate water tank (10) and then enters the aerobic biochemical tank (12) through a secondary lifting pump (11), sequentially flows through the subsequent compartments of the aerobic biochemical tank (12) and then flows out from the effluent pipe. Polyethylene suspended fillers (6) are added to the anoxic biochemical tank (5) for retaining anaerobic ammonia oxidation bacteria, and a stirrer (7) is arranged for stirring and mixing. High-density polyethylene suspended fillers (13) are added to the aerobic biochemical tank (12) for retaining nitrifying bacteria. An aeration disc (16) is arranged in the aerobic biochemical tank (12) and is supplied with air by a blower (14), and the aeration amount is controlled by an electromagnetic flowmeter (15). An on-line monitor (18) is arranged in the aerobic biochemical tank (12) to monitor the DO and pH in the aerobic biochemical tank (12) in real time. All the instruments and equipment are connected to the PLC control system (19) for control and digital visualization is realized through a display (20). The device and method for realizing deep denitrification and sludge reduction by continuous flow A / O in-situ hydrolysis acidification coupled with short-cut denitrification and anaerobic ammonia oxidation are characterized by comprising the following contents.

[0008] 1) System start-up: Inoculate ordinary residual sludge and anaerobic fermentation sludge from a sewage treatment plant in the anoxic biochemical tank (5) at a mass ratio of 10:1 to 20:1, and the mixed sludge concentration MLSS reaches 3000 to 4000 mg / L, of which the MLVSS accounts for more than 70%. At the same time, inoculate mature anaerobic ammonia oxidation biofilm fillers (6) in the anoxic biochemical tank (5) at a filling ratio of 10% to 20%. Inoculate only mature nitrifying biofilm fillers (13) in the aerobic biochemical tank (12) at a filling ratio of 30% to 50%, which is a pure biofilm system. The sewage tank (1) is for domestic sewage, and the sludge storage tank (2) is for residual sludge from a sewage treatment plant.

[0009] 2) System operation:

[0010] The residual sludge concentration in the sludge storage tank is 8000-10000 mg / L, the volume ratio of the sewage and residual sludge is 100:1-200:1, the sludge reflux ratio is 50%-75%, the anoxic biochemical tank (5) does not discharge residual sludge; the nitrification liquid reflux ratio is controlled in the range of 200%-400%, when the effluent nitrate concentration of the anoxic biochemical tank (5) is lower than 2 mg / L, the reflux ratio is increased, and vice versa.

[0011] The hydraulic retention time of the anoxic biochemical tank (5) is controlled in the range of 6-10 h, when the sludge concentration in the anoxic biochemical tank (5) rises more than 500 mg / L, the hydraulic retention time of the anoxic biochemical tank (5) is prolonged; the hydraulic retention time of the aerobic biochemical tank (12) is controlled in the range of 3-5 h, when the ammonia nitrogen concentration of the effluent of the aerobic biochemical tank (12) is higher than 2 mg / L, the hydraulic retention time of the aerobic biochemical tank (12) is prolonged, and vice versa; the dissolved oxygen in the last compartment of the aerobic biochemical tank (12) is controlled in the range of 2-3 mg / L.

[0012] When the sludge concentration of the anoxic biochemical tank (5) rises more than 1000 mg / L, anaerobic fermentation seed sludge is supplemented to the anoxic biochemical tank (5) to strengthen in-situ hydrolysis acidification, the sludge concentration of the anaerobic fermentation seed sludge is 5000-6000 mg / L, and the supplemented volume is 5%-10% of the volume of the anoxic biochemical tank (5).

[0013] The device and method for realizing deep denitrification and sludge reduction by continuous flow A / O in-situ hydrolysis acidification coupled short-range denitrification anaerobic ammonia oxidation have the following advantages:

[0014] 1) The problem of carbon source deficiency in the denitrification of low COD / N sewage is solved, and the short-range denitrification anaerobic ammonia oxidation technology is applied, so that the energy consumption, cost and environmental impact of sewage treatment are greatly reduced;

[0015] 2) The system not only does not produce residual sludge, but also can treat external residual sludge at the same time, so that the reduction and resource utilization of residual sludge are realized;

[0016] 3) The simultaneous treatment of sewage and sludge is realized, no additional structure is needed, the operation is simple, the implementability is strong, and the device can be widely applied to the upgrading and reconstruction of existing sewage treatment plants. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is the device diagram of the application.

[0018] Figure 1 In the figure, 1 is a sewage tank, 2 is a sludge storage tank, 3 is a sewage pump, 4 is a sludge pump, 5 is an anoxic biochemical tank, 6 is an anaerobic tank with a diameter of 25 mm and a specific surface area of 500 m 2 / m 3Polyethylene filler; 7-stirrer; 8-settling tank; 9-sludge return pump; 10-intermediate water tank; 11-secondary lifting pump; 12-aerobic biochemical tank; 13-diameter 25mm specific surface area 500m 2 / m 3 Polyethylene filler; 14-blower; 15-electromagnetic flowmeter; 16-aeration disc; 17-nitrification liquid return pump; 18-online monitor; 19-PLC control system; 20-display. DETAILED DESCRIPTION

[0019] In order to make the method of implementing the present application more clear, the present application is further described in detail with reference to the specific examples and the accompanying drawings. It should be noted that the following examples are only for illustration and to help understand the core idea and technical solution of the present application. The protection scope of the present application is not limited thereto.

[0020] System start-up: In the anoxic biochemical tank (5), inoculate ordinary residual sludge and anaerobic fermentation sludge from a sewage treatment plant at a mass ratio of 10:1, and the sludge concentration MLSS of the mixed sludge reaches 3500mg / L, wherein the MLVSS content is 75%. At the same time, inoculate mature anaerobic ammonia oxidation biofilm filler (6) in the anoxic biochemical tank (5) at a filling ratio of 20%. Inoculate only mature nitrification biofilm filler (13) in the aerobic biochemical tank (12) at a filling ratio of 40%, which is a pure biofilm system. The sewage tank (1) is for domestic sewage, and the sludge storage tank (2) is for residual sludge from a sewage treatment plant.

[0021] System operation parameters:

[0022] The residual sludge concentration in the sludge storage tank is 8000mg / L, the volume ratio of sewage and residual sludge is 150:1, the sludge return ratio is 60%, and the anoxic biochemical tank (5) does not discharge residual sludge; the nitrification liquid return ratio is 300%. The hydraulic retention time of the anoxic biochemical tank (5) is 8h, the hydraulic retention time of the aerobic biochemical tank (12) is 4h, and the dissolved oxygen in the last compartment of the aerobic biochemical tank (12) is controlled at 2-3mg / L.

[0023] The test uses domestic sewage from a certain community as raw water, and the specific water quality is as follows: ammonia nitrogen concentration: 40-50mg / L, nitrite concentration: 0-0.5mg / L; nitrate concentration: 0-1mg / L; COD concentration: 100-150mg / L; and the sludge from the secondary sedimentation tank of a certain sewage treatment plant is used as the source of residual sludge, and the sludge concentration is 8000-10000mg / L.

[0024] The test operation results show that after the system is stably operated, the effluent water quality is as follows: the TN concentration of the effluent is 9-11mg / L, the COD concentration is 25-35mg / L, and the ammonia nitrogen concentration is <2mg / L. The system can additionally treat residual sludge up to 0.67% of the influent amount per day.

[0025] It should be noted that the implementation methods not drawn or described in the drawings or the text of the specification are in the form known to those skilled in the art, and are not described in detail. In addition, the above definitions of each element are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and cannot be simply changed or replaced. Any modification made within the spirit and principles of the present application should be included within the scope of protection of the present application.

Claims

1. A method for achieving deep denitrification and sludge reduction by continuous flow A / O in-situ hydrolysis acidification coupled with short-cut denitrification and anaerobic ammonia oxidation, which comprises a sewage tank (1), a sludge storage tank (2), an anoxic biochemical tank (5), a sedimentation tank (8), an aerobic biochemical tank (12) and a PLC control system (19); sewage in the sewage tank (1) and residual sludge in the sludge storage tank (2) enter the first compartment of the anoxic biochemical tank (5) through a sewage pump (3) and a sludge pump (4) respectively, and at the same time, return sludge pumped in from the sedimentation tank (8) through a sludge return pump (9) and return nitrification liquid pumped in from the aerobic biochemical tank (12) through a nitrification liquid return pump (17) also enter the first compartment; the sludge-water mixture sequentially passes through the subsequent compartments of the anoxic biochemical tank (5) and then enters the sedimentation tank (8) for sludge-water separation, the supernatant enters an intermediate water tank (10) and then enters the aerobic biochemical tank (12) through a secondary lifting pump (11), sequentially flows through the subsequent compartments of the aerobic biochemical tank (12) and then flows out from a water outlet pipe; polyethylene suspended filler A is added to the anoxic biochemical tank (5) for retaining anaerobic ammonia oxidation bacteria, and a stirrer (7) is arranged for stirring and mixing; polyethylene suspended filler B is added to the aerobic biochemical tank (12) for retaining nitrifying bacteria; an aeration disc (16) is arranged in the aerobic biochemical tank (12) and is supplied with air by a blower (14), and the aeration amount is controlled by an electromagnetic flowmeter (15); an on-line monitor (18) is arranged in the aerobic biochemical tank (12) for real-time monitoring of DO and pH in the aerobic biochemical tank (12); all instruments and equipment are connected with the PLC control system (19) and realize digital visualization through a display (20); characterized in that comprising the following steps: 1) System start-up: inoculate the anoxic biochemical tank (5) with ordinary residual sludge and anaerobic fermentation sludge from a sewage treatment plant at a mass ratio of 10:1 to 20:1, the sludge concentration MLSS after mixing reaches 3000 to 4000 mg / L, and the MLVSS accounts for more than 70%; at the same time, inoculate the anoxic biochemical tank (5) with polyethylene suspended filler A with mature anaerobic ammonia oxidation biofilm at a filling ratio of 10% to 20%; inoculate the aerobic biochemical tank (12) with polyethylene suspended filler B with mature nitrifying biofilm at a filling ratio of 30% to 50%, which is a pure biofilm system; the sewage tank (1) contains domestic sewage, and the sludge storage tank (2) contains residual sludge treated in a sewage plant; 2) System operation: the concentration of residual sludge in the sludge storage tank is 8000 to 10000 mg / L, the volume ratio of sewage to residual sludge is 100:1 to 200:1, the sludge return ratio is 50% to 75%, and the anoxic biochemical tank (5) does not discharge residual sludge; the nitrification liquid return ratio is controlled within the range of 200% to 400%, and when the nitrate concentration of the effluent from the anoxic biochemical tank (5) is less than 2 mg / L, the return ratio is increased, and vice versa. ​ The hydraulic retention time of the anoxic biochemical tank (5) is controlled in the range of 6-10 h, when the sludge concentration in the anoxic biochemical tank (5) rises to more than 500 mg / L, the hydraulic retention time of the anoxic biochemical tank (5) is prolonged; the hydraulic retention time of the aerobic biochemical tank (12) is controlled in the range of 3-5 h, when the ammonia nitrogen concentration of the effluent of the aerobic biochemical tank (12) is higher than 2 mg / L, the hydraulic retention time of the aerobic biochemical tank (12) is prolonged, otherwise the hydraulic retention time is shortened; the dissolved oxygen in the last compartment of the aerobic biochemical tank (12) is controlled in the range of 2-3 mg / L; When the sludge concentration in the anoxic biochemical tank (5) rises to more than 1000 mg / L, anaerobic fermentation sludge is supplemented to the anoxic biochemical tank (5) to strengthen in-situ hydrolysis acidification, the sludge concentration of the anaerobic fermentation sludge is 5000-6000 mg / L, and the supplement volume is 5%-10% of the volume of the anoxic biochemical tank (5).

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