A double sedimentation sewage treatment device for high ammonia nitrogen and low carbon nitrogen ratio sewage

Abstract

The present invention discloses a dual-precipitation sewage treatment device for high-ammonia-nitrogen, low-carbon-nitrogen ratio sewage, comprising a biochemical reaction unit, a solid-liquid separation unit, and an equipment room, which are sequentially arranged. The biochemical reaction unit includes an anaerobic reaction zone, an anoxic reaction zone 1, an aerobic reaction zone, and an anoxic reaction zone 2, which are connected in sequence. A nitrification liquid return pipeline runs through the aerobic reaction zone, the anoxic reaction zone 1, and the anaerobic reaction zone and is located above each reaction zone. The solid-liquid separation unit includes a solid-liquid separation zone 1 and a solid-liquid separation zone 2 located above the solid-liquid separation zone 1. The sludge return pipeline runs through the solid-liquid separation zone 1, the anoxic reaction zone 2, the aerobic reaction zone, the anoxic reaction zone 1, and the anaerobic reaction zone and is located below the solid-liquid separation zone 1. The system of the present invention is highly integrated, occupies a small area, and has a high degree of automation. It can effectively reduce the impact of water volume changes on the sewage treatment system and has excellent treatment effects on domestic sewage with high ammonia-nitrogen, low carbon-nitrogen ratio, and a large flow rate variation coefficient.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and specifically designs a double-precipitation sewage treatment device for sewage with high ammonia nitrogen and low carbon-nitrogen ratio. Background Art

[0002] Decentralized domestic sewage is characterized by large fluctuations in water quality and quantity, intermittent discharge, and high management costs. Routine drainage monitoring or monitoring primarily focuses on indicators such as COD, ammonia nitrogen, total nitrogen, and total phosphorus. Typically, untreated domestic sewage has a COD concentration no greater than 350 mg / L, ammonia nitrogen no greater than 40 mg / L, total nitrogen no greater than 50 mg / L, and total phosphorus no greater than 5 mg / L. The carbon-nitrogen ratio (C / N) is typically between 5 and 8. This C / N ratio is a key indicator of nutrient sufficiency in domestic sewage, as a high C / N ratio favors biological reactions. However, in some areas, influent ammonia nitrogen and total nitrogen concentrations are elevated above typical values, while the C / N ratio is far below typical values, effectively failing to meet normal biochemical reactions. This is typical of high-ammonia-nitrogen, low-C / N ratio sewage, making it challenging to treat. Furthermore, with my country's increasingly stringent regulations on sewage discharge, existing sewage treatment systems and processes often struggle to consistently meet effluent standards. Therefore, the proper design of sewage treatment processes and corresponding control systems is crucial.

[0003] At present, traditional sewage treatment technology and control methods are generally used to treat decentralized domestic sewage with high ammonia nitrogen and low carbon nitrogen ratio. This often manifests as the problem that the effluent cannot stably meet the standards, especially the removal effect of total nitrogen is not ideal, and it is difficult to meet the drainage requirements. The reasons are mainly analyzed in four points: (1) The water volume of decentralized domestic sewage fluctuates greatly, and constant flow control cannot be achieved. This causes the water inlet lift pump to fluctuate with the change of the liquid level in the front-end regulating tank, and even intermittent operation, which has a certain impact on the biochemical system. Especially when the influent volume is large, it will have a greater impact on the secondary sedimentation tank at the rear end of the biochemical pool, thereby affecting the stability of the effluent water quality; (2) The use of traditional processes such as AO and AAO is not effective in removing total nitrogen, especially in the anaerobic reaction zone and the anoxic reaction zone. Due to the use of aeration stirring or natural flow without stirring, there will be short-flow or even reaction dead zones, which will cause the effluent, especially the total nitrogen, to fail to meet the standard stably; (3) The impact of water quality fluctuations was not considered at the beginning of the design, and the equipment structure was relatively fixed. When the influent water quality fluctuated greatly, the effluent could not meet the standard stably because the zones could not be flexibly adjusted; (4) In order to save costs, there is a lack of carbon source supplement mechanism for low carbon-nitrogen ratio sewage, and there is also a lack of reasonable water distribution methods, which affects the treatment effect of low carbon-nitrogen ratio sewage.

[0004] In summary, the present invention improves the existing sewage treatment equipment by analyzing the water quality and quantity characteristics of decentralized high-ammonia-nitrogen and low-carbon-nitrogen ratio sewage, realizes the stable operation of the system, ensures that the effluent can stably meet the standards, and ensures the removal effect of total nitrogen, providing a feasible solution for the treatment of decentralized high-ammonia-nitrogen domestic sewage. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a double-precipitation sewage treatment device for sewage with high ammonia nitrogen concentration and low carbon-nitrogen ratio. The sewage treated by the device can stably meet the standards and ensure the removal effect of total nitrogen.

[0006] The object of the present invention is achieved in the following ways:

[0007] A dual-precipitation sewage treatment device for high-ammonia nitrogen and low-carbon-nitrogen ratio sewage comprises a biochemical reaction unit, a solid-liquid separation unit and an equipment room arranged in sequence, wherein the biochemical reaction unit comprises an anaerobic reaction zone, an anoxic reaction zone 1, an aerobic reaction zone, and anoxic reaction zone 2 connected in sequence, and a nitrification liquid return pipeline passes through the aerobic reaction zone, the anoxic reaction zone 1 and the anaerobic reaction zone and is located above each reaction zone; the solid-liquid separation unit comprises a solid-liquid separation zone 1 and a solid-liquid separation zone 2 located above the solid-liquid separation zone 1, and a sludge return pipeline passes through the solid-liquid separation zone 1, the anoxic reaction zone 2, the aerobic reaction zone, the anoxic reaction zone 1 and the anaerobic reaction zone and is located below the solid-liquid separation zone 1.

[0008] The anaerobic reaction zone, anoxic reaction zone 1, aerobic reaction zone, anoxic reaction zone 2, and solid-liquid separation zone 2 are connected through a water inlet pipe, and a plurality of water inlets are provided on the water inlet pipe. An anaerobic zone water inlet valve is provided at the water inlet of the anaerobic reaction zone, an anoxic reaction zone 1 water inlet valve is provided at the water inlet of the anoxic reaction zone 1, and an anoxic reaction zone 1 water inlet valve is provided at the water inlet of the anoxic reaction zone 2.

[0009] The nitrification liquid reflux pipeline is provided with an anoxic reaction zone 1 reflux valve in the anoxic reaction zone 1, and is provided with an anaerobic zone reflux valve in the anaerobic reaction zone.

[0010] The anaerobic reaction zone can be freely converted between the anaerobic reaction zone and the anoxic zone according to the opening and closing of the valve on the nitrification liquid return pipeline, and the anoxic reaction zone 2 can be freely converted between the anoxic zone and the aerobic zone according to the opening and closing and the opening size of the valve on the aeration pipe; the anaerobic reaction zone, the anoxic reaction zone 1, and the anoxic reaction zone 2 can all realize free distribution of influent by opening and closing the valve and opening size of the water inlet pipeline of each reaction zone.

[0011] The nitrification liquid return pipeline can transport the mixed liquid in the aerobic reaction zone to the anaerobic reaction zone or the anoxic reaction zone 1 according to the opening and closing of the valve on the return pipeline. The return mixed liquid flow rate is 2 to 6 times the system inlet water flow rate.

[0012] The sludge return pipeline transports the bottom sewage of solid-liquid separation zone 1 to the anaerobic reaction zone. The sewage flow rate is 0.2 to 1 times the system inlet flow rate. The return mode is one or more combinations of air stripping return and pump return.

[0013] The equipment room is equipped with a blower control cabinet, a first dosing device, a second dosing device, and a second reflux device. The dosing pipeline connected to the first dosing device runs through the anaerobic reaction zone, anoxic reaction zone 1, aerobic reaction zone, anoxic reaction zone 2, and solid-liquid separation zone 2. Dosing ports are provided in each of the anaerobic reaction zone, anoxic reaction zone 1, aerobic reaction zone, and anoxic reaction zone 2, each equipped with a dosing valve. The dosing pipeline connected to the second dosing device runs through the anoxic reaction zone 2 and solid-liquid separation zone 1, each equipped with a dosing port, each equipped with a dosing valve. The control cabinet may contain a PLC, frequency converter, relay, etc.

[0014] The aerobic reaction zone is provided with a first reflux device, which is connected to the nitrification liquid reflux pipeline, and the sludge reflux pipeline is connected to the second reflux device in the equipment room.

[0015] The first dosing device can separately or simultaneously add chemicals to the anaerobic reaction zone, anoxic reaction zone 1, and anoxic reaction zone 2 via dosing line 1. The chemicals are one or more combinations of a composite carbon source, sodium acetate, glucose, and methanol. The second dosing device can separately or simultaneously add chemicals to the anoxic reaction zone 2 and solid-liquid separation zone 1 via dosing line 2. The chemicals are one or more combinations of polyaluminum chloride, polyferric chloride, aluminum sulfate, ferric chloride, and ferrous sulfate. If the dosing effect in the solid-liquid separation zone 1 is not obvious, dosing in the anoxic reaction zone 2 can be used to increase the flocculation reaction time and flocculation effect, which is more conducive to the removal of the pollutant TP.

[0016] Aeration systems are installed at the bottom of the aerobic reaction zone and anoxic reaction zone 2. Specifically, aeration pipes are installed at the bottom of each of these zones, and the solid-liquid separation zone 1. These pipes are connected to the blower system within the equipment room. Aeration valves are installed on the aeration pipes in the aerobic reaction zone and in the anoxic reaction zone 2. This allows for transitions from anoxic to aerobic zones, enabling flexible transitions between different process types.

[0017] The anaerobic reaction zone, anoxic reaction zone 1, and anoxic reaction zone 2 are each equipped with a liquid mixing and disturbance device. The device is a propeller agitator, paddle agitator, turbine agitator, or submersible flow impeller, with the impeller rotating at a speed of no less than 980 rpm. This prevents short-circuiting and even reaction dead zones, ensuring that the effluent, especially total nitrogen, meets standards.

[0018] The reaction zones are separated by partitions.

[0019] Each reaction zone of the biochemical reaction unit is provided with fillers.

[0020] A solid-liquid separation zone 1 mud discharge pipe is provided at the bottom of the solid-liquid separation zone 1, and an automatic mud discharge device for the solid-liquid separation zone 1 is provided on the mud discharge pipe.

[0021] A solid-liquid separation zone 2 mud discharge pipe is provided at the bottom of the solid-liquid separation zone 2, and an automatic solid-liquid separation zone 2 mud discharge device is provided on the mud discharge pipe.

[0022] The bottom of solid-liquid separation zone 1 and solid-liquid separation zone 2 is a cone or pyramid structure with a cone surface inclination of not less than 45 degrees. The bottom mud discharge pipe is equipped with a pump, electric valve, solenoid valve, manual valve or one or more combinations. The solid-liquid separation method can be one or more combinations of horizontal flow, vertical flow, inclined pipe / inclined plate. The hydraulic load of solid-liquid separation zone 1 can be between 1.0-2.0m 3 / (m 2 ·h), the hydraulic load of solid-liquid separation zone 2 can be between 0.4-1.0m 3 / (m 2 h). Flocculants may be added to the solid-liquid separation zone 1 and the front end. The sludge coagulants formed are larger and easier to settle. Therefore, a larger hydraulic load is set. The solid-liquid separation zone 2 is for reprecipitation of the sewage in zone 1. The sludge floccules are small and difficult to settle. Therefore, the hydraulic load is smaller than that of the solid-liquid separation zone 1.

[0023] The solid-liquid separation zone 2 is connected to a water outlet pipe, which passes through a disinfection device in the equipment room and is then discharged to the outside.

[0024] By utilizing the device of the present invention, a constant water inlet flow rate can be achieved by relying on the PLC, 380V water inlet lift pump, frequency converter and programmed control logic in the control cabinet.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention has a good treatment effect on domestic sewage with high ammonia nitrogen, low carbon-nitrogen ratio and large flow variation coefficient. The overall system is highly integrated, occupies a small area, and has a high degree of automation. The design of constant water inlet flow can effectively reduce the impact of water volume changes on the sewage treatment system; the back-end is equipped with two anoxic reaction zones to realize free switching of various operating modes according to the inlet water quality, and can have an excellent treatment effect on pollutants, especially total nitrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the overall structure of a double-precipitation sewage treatment device for high-ammonia-nitrogen and low-carbon-nitrogen ratio sewage provided by the present invention.

[0028] In the figure, 1-a double precipitation sewage treatment device for high ammonia nitrogen and low carbon nitrogen ratio sewage, 2-anaerobic reaction zone, 3-anoxic reaction zone 1, 4-aerobic reaction zone, 5-anoxic reaction zone 2, 6-solid-liquid separation zone 1, 7-solid-liquid separation zone 2, 8-equipment room, 9-reflux device 1, 10-control cabinet, 11-first dosing device, 12-blast device, 13-second dosing device, 14-reflux device 2, 15-sludge return pipeline 2, 16-dosing pipeline 2, 17-dosing pipeline 1, 18-reflux pipeline 1, 19-aeration pipe, 20-inlet Water pipe, 21-water inlet, 22-water outlet, 23-water inlet valve of anaerobic zone, 23-1-water inlet valve of anoxic reaction zone 1, 23-2-water inlet valve of anoxic reaction zone 2, 24-reflux valve in anaerobic zone, 24-1-reflux valve in anoxic reaction zone 1, 25-aeration valve 1, 25-1-aeration valve 2, 26-dosing valve, 27-sludge reflux valve, 28-sludge discharge pipe of solid-liquid separation zone 1, 28-1-automatic sludge discharge device of solid-liquid separation zone 1, 29-sludge discharge pipe of solid-liquid separation zone 2, 29-1-automatic sludge discharge device of solid-liquid separation zone 2. DETAILED DESCRIPTION

[0029] The present invention is further explained below by means of specific examples:

[0030] like Figure 1 As shown, a double-precipitation sewage treatment device for high-ammonia-nitrogen and low-carbon-nitrogen ratio sewage includes a biochemical reaction unit, a solid-liquid separation unit and an equipment room 8 arranged in sequence. The biochemical reaction unit includes an anaerobic reaction zone 2, an anoxic reaction zone 1 3, an aerobic reaction zone 4, and an anoxic reaction zone 2 5 connected in sequence. The nitrification liquid return pipeline 18 runs through the aerobic reaction zone 4, the anoxic reaction zone 1 3 and the anaerobic reaction zone 2 and is located at the upper part of each reaction zone; the solid-liquid separation unit includes a solid-liquid separation zone 1 6 and a solid-liquid separation zone 2 7 located above the solid-liquid separation zone 1 6. The sludge return pipeline 15 runs through the solid-liquid separation zone 1 6, the anoxic reaction zone 2 5, the aerobic reaction zone 4, the anoxic reaction zone 1 3 and the anaerobic reaction zone 2 and is located at the lower part of the solid-liquid separation zone 1 6. A water inlet pipe 20 is provided through the anaerobic reaction zone 2, the anoxic reaction zone 1 3, the aerobic reaction zone 4, the anoxic reaction zone 2 5, and the solid-liquid separation zone 2 7. The water inlet pipe 20 is provided with an anaerobic zone water inlet valve 23 at the water inlet of the anaerobic reaction zone 2, an anoxic reaction zone 1 water inlet valve 23-1 at the water inlet of the anoxic reaction zone 1 3, and an anoxic reaction zone 1 water inlet valve 23-2 at the water inlet of the anoxic reaction zone 2 5. The nitrification liquid reflux pipeline 18 is provided with an anoxic reaction zone 1 reflux valve 24-1 in the anoxic reaction zone 1 3 and an anaerobic zone reflux valve 24 in the anaerobic reaction zone 2.

[0031] The anaerobic reaction zone can be freely switched between the anaerobic reaction zone and the anoxic zone according to the opening and closing of the valve 24 on the nitrification liquid return pipe 18, and the anoxic reaction zone 2 can be freely switched between the anoxic zone and the aerobic zone according to the opening and closing and the opening size of the valve 25-1 on the aeration pipe; the anaerobic reaction zone, the anoxic reaction zone 1, and the anoxic reaction zone 2 can all realize free distribution of influent by opening and closing and the opening size of the valves 23, 23-1, and 23-2 of the water inlet pipes of each reaction zone.

[0032] The nitrification liquid return line 18 transports the mixed liquid from the aerobic reaction zone to the anaerobic reaction zone or anoxic reaction zone 1, depending on the opening and closing of the valve on the return line. The return mixed liquid flow rate is 2 to 6 times the system inlet flow rate. The sludge return line 15 transports the bottom sewage from the solid-liquid separation zone 1 to the anaerobic reaction zone, and the transported sewage flow rate is 0.2 to 1 times the system inlet flow rate. The return method can be one or a combination of air stripping reflux and pump reflux.

[0033] The equipment room is equipped with a blower 12, a control cabinet 10, a first dosing device 11, a second dosing device 13, and a second reflux device 14. The dosing pipeline connected to the first dosing device 11 runs through the anaerobic reaction zone 2, the anoxic reaction zone 1 3, the aerobic reaction zone 4, the anoxic reaction zone 2 5, and the solid-liquid separation zone 2 7. Each of these zones is equipped with a dosing port, each equipped with a dosing valve 26. The dosing pipeline connected to the second dosing device 13 runs through the anoxic reaction zone 2 5 and the solid-liquid separation zone 1 6. Each of these zones is equipped with a dosing port, each equipped with a dosing valve 26. The control cabinet may contain a PLC, a frequency converter, a relay, and other components. A first reflux device 9 is installed in the aerobic reaction zone 4 and is connected to the nitrification solution reflux pipeline 18.

[0034] The first dosing device 11 can add drugs separately or simultaneously in the anaerobic reaction zone, the anoxic reaction zone 1, and the anoxic reaction zone 2 through the dosing pipeline 117. The drugs are one or more combinations of a composite carbon source, sodium acetate, glucose, and methanol. The second dosing device 13 can add drugs separately or simultaneously in the anoxic reaction zone 2 and the solid-liquid separation zone 1 through the dosing pipeline 216. The drugs are one or more combinations of polyaluminum chloride, polyferric chloride, aluminum sulfate, ferric chloride, and ferrous sulfate.

[0035] An aeration pipe 19 is provided at the lower portion of the aerobic reaction zone 4, the anoxic reaction zone 2 5, and the solid-liquid separation zone 1 6, and the aeration pipe 19 is connected to the blower 12 in the equipment room 8. An aeration valve 25 is provided on the aeration pipe 19 of the aerobic reaction zone 4, and an aeration valve 25-1 is provided on the aeration pipe 19 of the anoxic reaction zone 2 5; the sludge return pipeline 15 is connected to the second reflux device 14 in the equipment room 8.

[0036] Anaerobic reaction zone 2, anoxic reaction zone 1 3, and anoxic reaction zone 2 5 are each equipped with a liquid mixing and disturbance device. This device is a propeller agitator, paddle agitator, turbine agitator, or submersible flow impeller, with the impeller speed being no less than 980 rpm. The reaction zones are separated by partitions. Each zone of the biochemical reaction unit is filled with filler.

[0037] The solid-liquid separation zone 2 7 is connected to the water outlet pipe 22 , and the water outlet pipe 22 passes through the disinfection device in the equipment room 8 to the outside.

[0038] The bottom of the solid-liquid separation zone 1 is provided with a solid-liquid separation zone 1 mud discharge pipe 28, and the mud discharge pipe is provided with an automatic mud discharge device 28-1; the bottom of the solid-liquid separation zone 2 is provided with a solid-liquid separation zone 2 mud discharge pipe 29, and the mud discharge pipe is provided with an automatic mud discharge device 29-1. The bottom of the solid-liquid separation zone 1 and the solid-liquid separation zone 2 is a cone or pyramid structure, and the inclination angle of the cone surface is not less than 45°. The mud discharge pipe at the bottom is installed with one or more combinations of pumps, electric valves, solenoid valves, and manual valves. The solid-liquid separation method can be one or more combinations of horizontal flow, vertical flow, inclined pipe / inclined plate. The hydraulic load of the solid-liquid separation zone 1 can be between 1.0-2.0m 3 / (m 2 ·h), the hydraulic load of solid-liquid separation zone 2 can be between 0.4-1.0m 3 / (m 2 ·h).

[0039] During operation: sewage mainly enters anaerobic reaction zone 2, anoxic reaction zone 1 3, aerobic reaction zone 4, anoxic reaction zone 2 5, solid-liquid separation zone 1 6, solid-liquid separation zone 2 7 in sequence through the water inlet pipe 22, among which a small part of sewage enters from the water inlet of anoxic reaction zone 1 3 and anoxic reaction zone 2 4, and finally the effluent from solid-liquid separation zone 2 7 is disinfected by the disinfection device in the equipment room 8 and then discharged.

[0040] Example 2

[0041] Specific application examples:

[0042] 1. Example 1 A sewage treatment plant with a treatment capacity of 20 t / d was used to culture and acclimate microorganisms by adding activated sludge until stable operation, and the COD, ammonia nitrogen, total nitrogen, and total phosphorus values ​​of the effluent were detected;

[0043] 2. The fillers arranged in each area of ​​the biochemical reaction unit are elastic fillers, soft fillers, composite fillers or one or more combinations thereof. The reagent added by the first dosing device is a carbon source, which is one or more combinations of methanol, sodium acetate, glucose, and composite carbon sources. The reagent added by the second dosing device is a flocculant, which is one or a combination of PAC and PAM. When the equipment is running stably, this embodiment uses automatic control to keep the water inlet flow constant at 0.83m 3 / h±0.02m 3 / h (i.e. 20t / d). The influent water quality fluctuates greatly, with COD concentration ranging from 39.68 to 228.88 mg / L, ammonia nitrogen concentration ranging from 10.41 to 65.6 mg / L, total nitrogen concentration ranging from 11.09 to 68 mg / L, and total phosphorus concentration ranging from 0.457 to 5.312 mg / L. The average influent C / N ratio is 2.22, indicating that the sewage is high in ammonia nitrogen and low in carbon-nitrogen ratio, with large fluctuations in water quality and difficult to treat.

[0044] 3. After sewage enters the equipment, sludge inoculation is first performed. This involves adding sludge to the anaerobic or anoxic reaction zone at a sludge concentration of 3500 mg / L. The total volume of the anaerobic, anoxic, and aerobic tanks is 61.34 m³. This requires 214.69 kg of absolute dry sludge, equivalent to 1.07 tons of sludge at 80% moisture content (calculated as 1 ton). Simultaneously, the agitators, aeration fans, and reflux pumps in the anaerobic and anoxic reaction zones are activated. After sludge addition, the system is aerated for two days to observe the SV30 (V / 30) value, the sludge state, and floc formation. Water is then intermittently introduced via a lift pump at a rate of 20% each time. Observe the SV30, sludge state, and floc formation daily. Gradually increase the influent load until the designed treatment capacity of 20 t / d is reached. Finally, the system enters the stable operation phase. Daily influent and effluent samples are collected for testing during the commissioning and stabilization phases.

[0045] 4. Using the device of Example 1, after nearly a month of stable operation, all indicators were able to stably meet the standards. The average concentration of COD effluent index was 45.73 mg / L (≤50 mg / L), the average concentration of ammonia nitrogen effluent index was 2.54 mg / L (≤5 mg / L), the average concentration of total nitrogen effluent index was 8.12 mg / L (≤15 mg / L), and the average concentration of total phosphorus effluent index was 1.82 mg / L (≤3 mg / L).

[0046] The above describes in detail preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art based on the concepts of the present invention through logical analysis, reasoning, or limited experimentation based on the existing technology should be within the scope of protection defined by the claims.

Claims

1. A double-precipitation sewage treatment device for high-ammonia-nitrogen and low-carbon-nitrogen ratio sewage, comprising a biochemical reaction unit, a solid-liquid separation unit and an equipment room (8) arranged in sequence, characterized in that The biochemical reaction unit comprises an anaerobic reaction zone (2), an anoxic reaction zone 1 (3), an aerobic reaction zone (4), and anoxic reaction zone 2 (5) connected in sequence, and a nitrification liquid return pipe (18) passes through the aerobic reaction zone (4), the anoxic reaction zone 1 (3) and the anaerobic reaction zone (2) and is located at the upper part of each reaction zone; the solid-liquid separation unit comprises a solid-liquid separation zone 1 (6) and a solid-liquid separation zone 2 (7) located above the solid-liquid separation zone 1 (6); a sludge return pipe (15) passes through the solid-liquid separation zone 1 (6), the anoxic reaction zone 2 (5), the aerobic reaction zone (4), the anoxic reaction zone 1 (3) and the anaerobic reaction zone (2) and is located at the lower part of the solid-liquid separation zone 1 (6); the anaerobic reaction The anaerobic reaction zone (2), the anoxic reaction zone 1 (3), the aerobic reaction zone (4), the anoxic reaction zone 2 (5), and the solid-liquid separation zone 2 (7) are connected by a water inlet pipe (20); a plurality of water inlets are provided on the water inlet pipe (20), an anaerobic zone water inlet valve (23) is provided at the water inlet of the anaerobic reaction zone (2), an anoxic reaction zone 1 water inlet valve (23-1) is provided at the water inlet of the anoxic reaction zone 1 (3), and an anoxic reaction zone 1 water inlet valve (23-2) is provided at the water inlet of the anoxic reaction zone 2 (5); the nitrification liquid reflux pipeline (18) is provided with an anoxic reaction zone 1 reflux valve (24-1) in the anoxic reaction zone 1 (3), and an anaerobic zone reflux valve (24) in the anaerobic reaction zone (2).

2. The double-precipitation sewage treatment device for high-ammonia-nitrogen and low-carbon-nitrogen ratio sewage according to claim 1 is characterized in that The equipment room is provided with an air blowing device (12), a control cabinet (10), a first dosing device (11), a second dosing device (13) and a second reflux device (14); a dosing pipeline connected to the first dosing device (11) passes through the anaerobic reaction zone (2), the anoxic reaction zone 1 (3), the aerobic reaction zone (4), the anoxic reaction zone 2 (5) and the solid-liquid separation zone 2 (7); dosing ports are provided in the anaerobic reaction zone (2), the anoxic reaction zone 1 (3), the aerobic reaction zone (4) and the anoxic reaction zone 2 (5); and dosing valves (26) are provided at the dosing ports; a dosing pipeline connected to the second dosing device (13) passes through the anoxic reaction zone 2 (5) and the solid-liquid separation zone 1 (6); dosing ports are provided in the anoxic reaction zone 2 (5) and the solid-liquid separation zone 1 (6); and dosing valves (26) are provided at the dosing ports.

3. The double-precipitation sewage treatment device for high-ammonia-nitrogen and low-carbon-nitrogen ratio sewage according to claim 1 is characterized in that An aeration pipe (19) is provided at the lower portion of the aerobic reaction zone (4), the anoxic reaction zone 2 (5) and the solid-liquid separation zone 1 (6), and the aeration pipe (19) is connected to the blower device (12) in the equipment room (8). An aeration valve (25) is provided on the aeration pipe (19) of the aerobic reaction zone (4), and an aeration valve (25-1) is provided on the aeration pipe (19) of the anoxic reaction zone 2 (5). The sludge return pipeline (15) is connected to the second return device (14) in the equipment room (8).

4. The double-precipitation sewage treatment device for high-ammonia-nitrogen and low-carbon-nitrogen ratio sewage according to claim 1 is characterized in that A first reflux device (9) is provided in the aerobic reaction zone (4), and the first reflux device (9) is connected to the nitrification liquid reflux pipeline (18).

5. The double-precipitation sewage treatment device for high-ammonia-nitrogen and low-carbon-nitrogen ratio sewage according to claim 1 is characterized in that The anaerobic reaction zone (2), the anoxic reaction zone 1 (3), and the anoxic reaction zone 2 (5) are all provided with a liquid mixing disturbance device.

6. The double-precipitation sewage treatment device for high-ammonia-nitrogen and low-carbon-nitrogen ratio sewage according to claim 1 is characterized in that The reaction zones are separated by partitions.

7. The double-precipitation sewage treatment device for high-ammonia-nitrogen and low-carbon-nitrogen ratio sewage according to claim 1 is characterized in that Each reaction zone of the biochemical reaction unit is provided with fillers.

8. The double-precipitation sewage treatment device for high-ammonia-nitrogen and low-carbon-nitrogen ratio sewage according to claim 7 is characterized in that The solid-liquid separation zone 2 (7) is connected to the water outlet pipe (22), and the water outlet pipe (22) passes through the disinfection device in the equipment room (8) to the outside.

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