A system and method suitable for decentralized domestic sewage treatment

Abstract

The invention discloses a system and method suitable for decentralized domestic sewage treatment, comprising a water inlet pipe, a reaction tank, a sedimentation tank and a water production pipe which are connected in sequence; an intermittent water outlet pipe and a continuous water outlet pipe with an on-off valve are connected between the reaction tank and the sedimentation tank; a sedimentation tank inclined pipe is arranged in the sedimentation tank, the water production pipe and the intermittent water outlet pipe are arranged at the upper part of the sedimentation tank inclined pipe, and the continuous water outlet pipe is arranged at the lower part of the sedimentation tank inclined pipe; the reaction tank is divided into at least two compartments, each compartment is provided with an aeration device, and the aeration device in each compartment can be opened and closed separately; the invention arranges a continuous water outlet pipe and an intermittent water outlet pipe in a traditional intermittently operated SBR process system, which can be switched to an intermittent operation mode or a continuous operation mode according to changes in the amount of sewage, thereby being able to better adapt to changes in the amount of sewage and being suitable for decentralized domestic sewage treatment.

Description

Technical Field

[0001] The present invention relates to the field of sewage treatment, and in particular to a system and method suitable for decentralized domestic sewage treatment. Background Art

[0002] The full name of the traditional SBR method is the sequencing batch activated sludge method, which is a new type of aerobic biological treatment technology. It uses a variable intermittent reactor to provide time-programmed sewage treatment, rather than space-programmed sewage treatment provided by continuous flow. The traditional SBR method performs basic operations such as water inflow, reaction (aeration), sedimentation, water discharge, and standby (idle) in chronological order. From the beginning of sewage inflow to the end of the standby time is a cycle, and this cycle is repeated to achieve the purpose of sewage purification.

[0003] MBR (Membrane Bioreactor): A new water treatment technology that combines a membrane separation unit with a biological treatment unit. The membrane components replace the terminal secondary sedimentation tank of the traditional biological treatment technology, maintain a high concentration of activated sludge in the bioreactor, and increase the organic load of biological treatment. It is also a biochemical method, which mainly relies on the synthesis and decomposition of microorganisms to remove water quality indicators in the water. The MBR (Membrane Bioreactor) method has high construction costs and high technical requirements for operation and maintenance. The ability to resist shock loads is poor. In order to meet the discharge standards and reduce the impact of changes in water quality and water volume, most of them are currently set up in front of the treatment equipment. The longer the residence time, the stronger the buffering capacity, which increases the floor space and construction investment. In addition, the later operation and maintenance have high requirements for personnel, and the maintenance and replacement costs of membrane components are high. In addition, the replaced membrane components are solid waste and difficult to be treated greenly.

[0004] In recent years, with the improvement of rural living environment, rural domestic sewage treatment has been vigorously developed. In the northern region, for example, in Tianjin, there are thousands of rural sewage treatment stations, and each village has one or more treatment stations. Unlike urban or city sewage treatment plants, which are concentrated, they are decentralized small-scale sewage treatment systems. Most of the rural domestic sewage treatment in Baodi District, Ninghe District, etc. adopts MBR technology (in the south, due to the high temperature, the anoxic-aerobic-sedimentation technology is adopted, and there are also different technologies such as artificial rapid infiltration and purification tanks).

[0005] In the actual operation process, due to the large changes in water quality and water volume of decentralized domestic sewage, especially rural sewage, it is greatly affected by the number of residents and living habits. For example, the drainage volume in rural areas is large during breakfast, lunch and dinner, and less at other times. The drainage patterns in different seasons are also different. The above-mentioned MBR process and SBR process are not well adapted to decentralized domestic sewage treatment. Summary of the invention

[0006] The object of the present invention is to provide a system and method suitable for decentralized domestic sewage treatment to solve the problems existing in the above-mentioned prior art. A continuous outlet pipe and an intermittent outlet pipe are set in the traditional intermittently operated SBR process system, which can switch to an intermittent operation mode or a continuous operation mode according to the change of sewage volume, thereby being able to better adapt to the change of sewage volume and being suitable for decentralized domestic sewage treatment.

[0007] To achieve the above object, the present invention provides the following solutions:

[0008] The present invention provides a system suitable for decentralized domestic sewage treatment, comprising a water inlet pipe, a reaction tank, a sedimentation tank and a water production pipe which are connected in sequence; an intermittent water outlet pipe and a continuous water outlet pipe with an on-off valve are connected between the reaction tank and the sedimentation tank; a sedimentation tank inclined pipe is arranged in the sedimentation tank, the water production pipe and the intermittent water outlet pipe are arranged at the upper part of the sedimentation tank inclined pipe, and the continuous water outlet pipe is arranged at the lower part of the sedimentation tank inclined pipe; the reaction tank is divided into at least two compartments, each compartment is provided with an aeration device, and the aeration device in each compartment can be opened and closed separately.

[0009] Preferably, the reaction tank is divided into four compartments, and two adjacent compartments are connected at the bottom or the top to form an S-shaped flow path for the sewage.

[0010] Preferably, a sludge return pipe is provided between the sedimentation tank and the reaction tank.

[0011] Preferably, a decanter is provided between the reaction tank and the intermittent water outlet pipe or the continuous water outlet pipe, and sewage flows out of the reaction tank and enters the intermittent water outlet pipe or the continuous water outlet pipe after passing through the decanter.

[0012] Preferably, a filter cloth is provided between the sedimentation tank and the water production pipe, and the sewage flows out from the water production pipe after being filtered by the filter cloth.

[0013] Preferably, it comprises a dosing device, and the drugs added by the dosing device include glucose and PAC polyaluminium chloride.

[0014] The present invention also provides a method suitable for decentralized domestic sewage treatment, comprising the following steps:

[0015] (1) Setting a sewage volume threshold. When the amount of sewage to be treated is less than the sewage volume threshold, select the intermittent operation mode. When the amount of sewage to be treated exceeds the sewage volume threshold, select the continuous operation mode.

[0016] (2) When intermittent operation is selected:

[0017] (2.1) The sewage enters the reaction tank through the water inlet pipe, and the water inlet is stopped when the designed liquid level is reached;

[0018] (2.2) Carrying out aeration reaction;

[0019] (2.3) Stop aeration reaction and enter the sedimentation stage;

[0020] (2.4) After the sedimentation stage is completed, the produced water is discharged to the outside through the water production pipe;

[0021] (3) When selecting continuous operation mode:

[0022] (3.1) The aeration device of the first compartment is turned off to make it an anoxic tank; sewage continuously flows into the first compartment through the water inlet pipe, and at the same time, the sludge in the sedimentation tank also flows back into the first compartment;

[0023] (3.2) Turn on the aeration devices of other cells to make them aerobic tanks; sewage enters the first cell continuously and flows through other cells in sequence;

[0024] (3.3) When the sewage level in the reaction tank reaches the set level, the sewage enters the sedimentation tank for sedimentation;

[0025] (3.4) The sewage after sedimentation is discharged to the outside through the water production pipe.

[0026] Preferably, the dissolved oxygen in the anoxic tank in step (3.1) is controlled at 0.2-0.5 mg / L, and the dissolved oxygen in the aerobic tank in step (3.2) is controlled at 2-4 mg / L.

[0027] Preferably, in step (3.4), the sewage is precipitated from bottom to top through the inclined tube of the sedimentation tank and then discharged outward through the water production pipe.

[0028] Preferably, when the carbon source or the influent carbon source is insufficient, a reagent is added into the reaction tank, and the reagent is glucose.

[0029] Compared with the prior art, the present invention has achieved the following technical effects:

[0030] (1) The present invention sets a continuous outlet pipe and an intermittent outlet pipe in a traditional SBR process system, which can be switched to an intermittent operation mode or a continuous operation mode according to changes in the amount of sewage. When the amount of sewage to be treated is small, the SBR process is intermittently operated, which can reduce the operating cost. When the amount of sewage to be treated is large, the continuous operation mode is adopted, which can improve the sewage treatment efficiency, thereby being able to better adapt to changes in the amount of sewage and being suitable for decentralized domestic sewage treatment;

[0031] (2) The present invention adopts a continuous operation mode when the amount of sewage is large, which can reduce the volume of the regulating tank in front of the reaction tank, thereby reducing the construction investment and better meeting the needs of decentralized sewage treatment in rural areas;

[0032] (3) The present invention provides a sedimentation tank inclined pipe in the sedimentation tank. During continuous operation, sewage passes through the sedimentation tank inclined pipe for sedimentation and then flows out through the water production pipe, thereby improving the sewage treatment effect during continuous operation, especially when there is sludge return. During intermittent operation, sewage does not need to pass through the sedimentation tank inclined pipe, thereby ensuring the efficiency during intermittent operation. Therefore, the present invention can better adapt to different treatment methods and ensure or improve the effect or efficiency of sewage treatment.

[0033] (4) The reaction tank of the present invention is divided into multiple grids that are interconnected to form an S-shaped flow path. On the one hand, the anoxic tank and the aerobic tank can be formed by opening and closing the aeration device, respectively, as different process units to treat different pollution sources. On the other hand, the water flow can be diverted to form an S-shaped flow pattern, thereby increasing the mixing degree of sewage in the reaction tank to further improve the treatment effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] 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 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 these drawings without paying creative labor.

[0035] Figure 1 is a process flow chart of the present invention;

[0036] Figure 2 It is a schematic diagram of the top view of the structure of the system of the present invention;

[0037] Figure 3 for Figure 2 A schematic diagram of a side cross-sectional structure;

[0038] Among them, 1. water inlet pipe; 2. reaction tank; 3. sedimentation tank; 4. water production pipe; 5. aeration device; 6. aeration pipe; 7. blower; 8. electric control box; 9. dosing device; 10. decanter; 11. continuous water outlet pipe; 12. intermittent water outlet pipe; 13. filter cloth; 14. sedimentation tank inclined pipe; 15. sludge return pipe. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of 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.

[0040] The purpose of the present invention is to provide a system and method suitable for decentralized domestic sewage treatment to solve the problems existing in the prior art. A continuous outlet pipe and an intermittent outlet pipe are set in a traditional intermittently operated SBR process system, which can switch to an intermittent operation mode or a continuous operation mode according to changes in the amount of sewage, thereby being able to better adapt to changes in the amount of sewage and being suitable for decentralized domestic sewage treatment.

[0041] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] The present invention provides a system suitable for decentralized domestic sewage treatment, such as Figure 2-3As shown, it includes an inlet pipe 1, a reaction tank 2, a sedimentation tank 3 and a water production pipe 4 which are connected in sequence, wherein the inlet pipe 1 can be connected to a raw water pump for sending sewage into the reaction tank 2, and a regulating tank can be arranged before the inlet pipe 1 for temporarily storing sewage, and the amount of sewage entering the reaction tank 2 can be adjusted according to the amount of sewage to be treated. For example, if the amount of sewage to be treated increases occasionally due to the influence of precipitation, the sewage can be temporarily stored in the regulating tank and an intermittent operation mode can be adopted; when there are factors such as continuous precipitation that cause the amount of sewage to continue to increase, the regulating tank may no longer meet the requirements of regulating the water volume due to its limited volume, and the continuous operation mode can be turned on. Therefore, the present invention adopts a method of switching between continuous operation and intermittent operation, which can reduce the dependence on the volume of the regulating tank, so that a smaller regulating tank can be built to reduce engineering investment and cost. The system also includes an electric control box 8, which automatically or manually controls the operation of each device in the system. The reaction tank 2 is divided into at least two compartments, each compartment is provided with an aeration device 5, the aeration device 5 can be an aeration plate or an aeration pipe, the aeration device 5 is connected to the blower 7 through the aeration pipe 6, the blower 7 provides a gas source for the aeration device 5, the aeration device 5 in each compartment can be opened and closed individually, and this process can be achieved by setting an on-off valve on the aeration pipe 6, and the valve can be an electromagnetic valve, which can be remotely controlled or automatically controlled. During intermittent operation, the aeration device 5 of each compartment can be opened to enable the SBR (sequencing batch activated sludge process) treatment process. During continuous operation, the aeration device 5 of the first compartment can be closed and the aeration devices 5 of other compartments can be opened to form an anoxic environment in the first compartment and an aerobic environment in other compartments, so as to meet the demand for sewage treatment in the continuous operation state. An intermittent water outlet pipe 12 with an on-off valve and a continuous water outlet pipe 11 are connected between the reaction tank 2 and the sedimentation tank 3. The on-off valve can be an electric valve or a manual valve. When the system is in intermittent operation, the valve of the intermittent water outlet pipe 12 is opened (the valve of the continuous water outlet pipe 11 is closed at this time), so that the sewage enters the sedimentation tank 3 from the reaction tank 2 through the intermittent water outlet pipe 12. When the system is in continuous operation, the valve of the continuous water outlet pipe 11 is opened (the valve of the intermittent water outlet pipe 12 is closed at this time), so that the sewage enters the sedimentation tank 3 from the reaction tank 2 through the continuous water outlet pipe 11.It should be noted that the intermittent water outlet pipe 12 and the continuous water outlet pipe 11 are respectively connected at different positions on the sedimentation tank 3 in vertical height. Specifically, a sedimentation tank inclined pipe 14 is provided in the sedimentation tank 3, the intermittent water outlet pipe 12 is provided at the upper part of the sedimentation tank inclined pipe 14, and the continuous water outlet pipe 11 is provided at the lower part of the sedimentation tank inclined pipe 14; in addition, the water production pipe 4 is provided at the upper part of the sedimentation tank inclined pipe 14. Therefore, when the system of the present invention is in continuous operation, the sewage is precipitated through the sedimentation tank inclined pipe 14 and then flows out through the water production pipe 4, thereby improving the treatment effect of the sewage during continuous operation, especially when there is sludge backflow; during intermittent operation, the sewage does not need to pass through the sedimentation tank inclined pipe 14, which can ensure the efficiency during intermittent operation, so that the present invention can better adapt to different treatment methods and ensure or improve the effect or efficiency of sewage treatment. Therefore, the present invention sets a continuous outlet pipe 11 and an intermittent outlet pipe 12 in the traditional SBR process system, which can switch to an intermittent operation mode or a continuous operation mode according to the change of sewage volume. When the amount of sewage to be treated is small, the SBR process can be operated intermittently, which can reduce the operation cost. When the amount of sewage to be treated is large, the continuous operation mode can be adopted, which can improve the sewage treatment efficiency, thereby being able to better adapt to the change of sewage volume and being suitable for decentralized domestic sewage treatment.

[0043] The reaction tank 2 can be divided into four interconnected grids, and the grids can be separated by baffles. The position of the baffles is not unique. Therefore, the size of each grid can be adjusted according to the actual process and conditions, that is, the size of each grid can be equal or unequal. It should be noted that after the baffle is set, the adjacent grids can be connected at the top or at the bottom. In order to further achieve the effect of treating sewage, the connecting position can also be set at intervals. For example, the first grid and the second grid are connected at the bottom, and the second grid and the third grid are connected through the top. Further, the third grid and the fourth grid are connected again through the bottom. Of course, the connection order from the first grid to the fourth grid can also be, first the top, then the bottom, and then the top. No matter which connection mode is used, the sewage can form an S-shaped flow path in the reaction tank 2. On the one hand, each grid forms an incompletely connected reaction tank 2, which can form an anoxic tank and an aerobic tank respectively by opening and closing the aeration device 5 to treat different pollution sources. On the other hand, the water flow can be diverted to form an S-shaped flow mode to improve the mixing degree of sewage in the reaction tank 2, so as to further improve the treatment effect.

[0044] A sludge return pipe 15 may be provided between the sedimentation tank 3 and the reaction tank 2. The sludge return pipe 15 is used to return the sludge in the sedimentation tank 3 into the reaction tank 2. A reflux pump may be installed on the sludge return pipe 15 to drive the reflux of the sludge. It should be noted that the sludge return pipe 15 should be connected to the first cell of the reaction tank 2, that is, the returned sludge can flow to other cells through the first cell in the reaction tank 2; the sludge can provide a favorable environment for the growth of microorganisms, and is conducive to the reproduction of microorganisms and nitrifying bacteria in an aerobic environment, thereby being able to degrade or adsorb organic pollution such as carbon and ammonia nitrogen in sewage.

[0045] A decanter 10 may be provided between the reaction tank 2 and the intermittent outlet pipe 12 and the continuous outlet pipe 11. The decanter 10 may be installed in the reaction tank 2, that is, the intermittent outlet pipe 12 and the continuous outlet pipe 11 are arranged in parallel at the outlet of the decanter 10, so that the sewage in the reaction tank 2 passes through the decanter 10 and then enters the intermittent outlet pipe 12 or the continuous outlet pipe 11. The decanter 10 can be divided into siphon type, rotary type, self-floating type, mechanical type and other types, which belong to the existing equipment. The decanter 10 is generally a device for regularly removing clarified water in the SBR process. It has the function of decanting clarified water from the surface of the static reaction tank 2 without stirring the sediment, and ensuring the water quality of the effluent during intermittent operation. The present invention arranges the decanter 10 in parallel on the decanter 10, which can be used both in intermittent operation and in continuous operation, so that the amount of sludge entering the sedimentation tank 3 can be reduced during continuous operation to ensure the effluent quality of the sedimentation tank 3.

[0046] A filter cloth 13 can be provided between the sedimentation tank 3 and the water production pipe 4. The filter cloth 13 can be provided inside the sedimentation tank 3. The sewage after sedimentation is filtered by the filter cloth 13 and then flows out of the water production pipe 4. It can be filtered again before water production to further improve the quality of water production.

[0047] A dosing device 9 can also be provided, and the dosing device 9 adds reagents to the front end and the rear end of the reaction tank 2 respectively. The added reagents include glucose and PAC polyaluminium chloride, and the amount of the added reagents is adjusted according to the actual amount of water treated. Among them, glucose is mainly added to the front end of the reaction tank 2 to provide a carbon source for denitrifying bacteria, and is added when the carbon source and the influent carbon source are insufficient; PAC polyaluminium chloride is mainly added to the front end of the reaction tank 2 (it can also be added to the rear end of the reaction tank 2) for phosphorus removal, and is added according to the total phosphorus content of the influent combined with the effluent standard. Sodium hypochlorite can also be added to the final produced water for disinfection.

[0048] The present invention also provides a method suitable for decentralized domestic sewage treatment, such as Figure 1 Shown and combined Figure 2-3 , the decentralized domestic sewage treatment system mentioned above can be applied, including the following steps:

[0049] (1) Setting a sewage volume threshold. The sewage volume threshold is set according to the processing capacity of the equipment actually constructed, and the processing capacity needs to be determined by investigation and analysis based on the needs of the actual site constructed; for example, the sewage volume threshold set by the system in a certain area is 100 tons / day. When the sewage volume to be processed is less than the sewage volume threshold, the intermittent operation mode is selected. When the sewage volume to be processed exceeds the sewage volume threshold (for example, 110 tons / day), the continuous operation mode is selected. As for how to monitor the amount of sewage, a flow monitoring device can be set on the inlet side of the system (if a regulating tank is set, the sewage volume can also be fed back according to the change of the liquid level of the regulating tank). When the sewage volume is monitored to exceed or fall below the sewage volume threshold, the system operation mode can be manually switched from intermittent operation mode to continuous operation mode, or from continuous operation mode to intermittent operation mode; of course, the sewage volume signal can also be transmitted to the automatic control device so that the switch signal can be transmitted to the solenoid valve on the continuous outlet pipe 11 or the intermittent outlet pipe 12 to achieve automatic control.

[0050] (2) When the intermittent operation mode is selected, the SBR mode can be used. In this operation mode, water inlet, reaction, precipitation, water outlet, standby, etc. are all carried out in the reaction tank 2. Specifically:

[0051] (2.1) Sewage enters the reaction tank 2 through the water inlet pipe 1, and the water inflow stops when the designed liquid level is reached. It should be noted that the designed liquid level is the optimal water level of the system during intermittent operation, which can be designed and determined according to the system's processing capacity in the early stage of system design;

[0052] (2.2) turning on the aeration device 5 to carry out an aeration reaction. If the reaction tank 2 is divided into multiple compartments, turning on the aeration device 5 in each compartment;

[0053] (2.3) After a period of reaction, check whether the various treatment data in the sewage have reached the treatment target. If so, stop the aeration reaction. If not, continue the aeration reaction until the treatment target is reached, and then enter the sedimentation stage;

[0054] (2.4) When the water quality meets the requirements, the sedimentation stage ends, and the valve of the continuous water outlet pipe 11 is opened to allow the sewage to enter the sedimentation tank 3 and be discharged to the outside through the water production pipe 4.

[0055] (3) When the continuous operation mode is selected, the anoxic + aerobic + inclined tube sedimentation mode can be used. The water flow direction of the reaction tank 2 is the same as that of the intermittent operation, but it flows continuously:

[0056] (3.1) The reaction tank 2 is divided into multiple compartments. The aeration device 5 of the first compartment is turned off. The solenoid valve system can be set to automatically start and stop according to the switching process to control the dissolved oxygen within a certain range, which serves as an anoxic tank. The sewage continuously enters the first compartment from the water inlet pipe 1. At the same time, the sludge from the sedimentation tank 3 also flows back into the first compartment. The primary function of the anoxic tank is denitrification. The denitrifying bacteria use the organic matter in the sewage as a carbon source to remove the NO3 - and NO2 - Reduced to N2 and released into the air, BOD concentration continues to decrease, NO3 - The concentration also dropped significantly;

[0057] (3.2) Open the aeration device 5 of the other compartments of the reaction tank 2. The solenoid valve system can be set to automatically start and stop according to the switching process to control the dissolved oxygen within a certain range, so as to serve as an aerobic tank; the sewage enters the first compartment continuously and flows through the other compartments in sequence. Under the aeration state, the microorganisms and nitrifying bacteria that multiply in large quantities in the activated sludge can degrade or adsorb organic pollutants such as carbon and ammonia nitrogen in the water to achieve the purpose of purifying the water quality; the aeration device 5 can use a tubular rubber microporous aerator with a good oxygen transfer rate;

[0058] (3.3) As the amount of sewage entering the reaction tank 2 gradually increases, the sewage level in the reaction tank 2 gradually rises. When the set level is reached, the valve of the continuous outlet pipe 11 is opened to allow the sewage to enter the sedimentation tank 3 for sedimentation;

[0059] (3.4) The sewage after settling in the sedimentation tank 3 is discharged outward through the water production pipe 4. A filter cloth 13 can also be arranged before the water production pipe 4 to enable filtering again before water production, thereby further improving the sewage treatment effect.

[0060] The dissolved oxygen in the anoxic tank in step (3.1) can be controlled at 0.2-0.5 mg / L, and the dissolved oxygen in the aerobic tank in step (3.2) can be controlled at 2-4 mg / L.

[0061] In step (3.4), a sedimentation tank inclined pipe 14 can be arranged in the sedimentation tank 3, the continuous outlet pipe 11 is arranged at the lower part of the sedimentation tank inclined pipe 14, and the water production pipe 4 is arranged at the upper part of the sedimentation tank inclined pipe 14. During continuous operation, the sewage is precipitated through the sedimentation tank inclined pipe 14 and then flows out through the water production pipe 4, thereby improving the sewage treatment effect during continuous operation, especially when there is sludge backflow.

[0062] If the carbon source in the reaction tank 2 and the carbon source in the influent are insufficient, a reagent can be added to the reaction tank 2. The reagent is glucose. The amount of glucose added is added according to actual needs, and it is mainly added at the front end of the reaction tank 2. In addition, PAC polyaluminum chloride can also be added to the reaction tank 2 for phosphorus removal. It is added according to the total phosphorus content of the influent and the effluent standard, and it is mainly added at the front end of the reaction tank 2 (it can also be added at the rear end of the reaction tank 2).

[0063] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A system suitable for decentralized domestic sewage treatment, characterized in that: It comprises a water inlet pipe, a reaction tank, a sedimentation tank and a water production pipe which are connected in sequence; an intermittent water outlet pipe and a continuous water outlet pipe with an on-off valve are connected between the reaction tank and the sedimentation tank; a sedimentation tank inclined pipe is arranged in the sedimentation tank, the water production pipe and the intermittent water outlet pipe are arranged at the upper part of the sedimentation tank inclined pipe, and the continuous water outlet pipe is arranged at the lower part of the sedimentation tank inclined pipe; the reaction tank is divided into at least two compartments, each compartment is provided with an aeration device, and the aeration device in each compartment can be opened and closed separately; A sludge return pipe is provided between the sedimentation tank and the reaction tank; A decanter is arranged between the reaction tank and the intermittent water outlet pipe or the continuous water outlet pipe. Sewage flows out of the reaction tank and enters the intermittent water outlet pipe or the continuous water outlet pipe after passing through the decanter.

2. The system for decentralized domestic sewage treatment according to claim 1, characterized in that: The reaction pool is divided into four compartments, and two adjacent compartments are connected at the bottom or the top to form an S-shaped flow path for sewage.

3. The system for decentralized domestic sewage treatment according to claim 1, characterized in that: A filter cloth is arranged between the sedimentation tank and the water production pipe, and the sewage flows out from the water production pipe after being filtered by the filter cloth.

4. The system for decentralized domestic sewage treatment according to claim 1, characterized in that: It comprises a dosing device, and the drugs added by the dosing device include glucose and PAC polyaluminium chloride.

5. A method for decentralized domestic sewage treatment, using the system for decentralized domestic sewage treatment according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) Setting a sewage volume threshold. When the amount of sewage to be treated is less than the sewage volume threshold, select the intermittent operation mode. When the amount of sewage to be treated exceeds the sewage volume threshold, select the continuous operation mode. (2) When intermittent operation is selected: (2.1) The sewage enters the reaction tank through the water inlet pipe, and the water inlet is stopped when the designed liquid level is reached; (2.2) Carrying out aeration reaction; (2.3) Stop aeration reaction and enter the sedimentation stage; (2.4) After the sedimentation stage is completed, the produced water is discharged to the outside through the water production pipe; (3) When selecting continuous operation mode: (3.1) The aeration device of the first compartment is turned off to make it an anoxic tank; sewage continuously flows into the first compartment through the water inlet pipe, and at the same time, the sludge in the sedimentation tank also flows back into the first compartment; (3.2) Turn on the aeration devices of other cells to make them aerobic tanks; sewage enters the first cell continuously and flows through other cells in sequence; (3.3) When the sewage level in the reaction tank reaches the set level, the sewage enters the sedimentation tank for sedimentation; (3.4) The sewage after sedimentation is discharged to the outside through the water production pipe.

6. The method for decentralized domestic sewage treatment according to claim 5, characterized in that: In step (3.1), the dissolved oxygen in the anoxic tank is controlled at 0.2-0.5 mg / L, and in step (3.2), the dissolved oxygen in the aerobic tank is controlled at 2-4 mg / L.

7. The method for decentralized domestic sewage treatment according to claim 5, characterized in that: In step (3.4), the sewage is precipitated from bottom to top through the inclined tube of the sedimentation tank and then discharged outward through the water production pipe.

8. The method for decentralized domestic sewage treatment according to claim 5, characterized in that: When the carbon source and the influent carbon source are insufficient, a reagent is added into the reaction tank, and the reagent is glucose.

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