EP4253675A1

EP4253675A1 - Online draft-in-place gravity sewage discharging device and method, and suction and blowing-off system and method

Info

Publication number: EP4253675A1
Application number: EP21896212.4A
Authority: EP
Inventors: Bin Fan; Shikun ZHU; Tingting QIAN; Hongqiao ZHANG; Yunjiao MA
Original assignee: Changshu Guoke Aiwei Rural Drainage Engineering Technology Co Ltd; Research Center for Eco Environmental Sciences of CAS
Current assignee: Changshu Guoke Aiwei Rural Drainage Engineering Technology Co Ltd; Research Center for Eco Environmental Sciences of CAS
Priority date: 2020-11-30
Filing date: 2021-05-26
Publication date: 2023-10-04
Also published as: CN112554301A; WO2022110702A1

Abstract

The present disclosure provides a device and a method for drafting air in field and in-situ unloading sewage based on gravity, and a system and a method for discharging suction sewage. The device for drafting air in field and unloading sewage based on gravity includes: a container body including a feeding port and a discharging port, wherein the feeding port is configured to allow a sewage to pass into an interior of the container body when the interior of the container body is in a negative pressure state; an air drafting assembly, located at a top of the container body and configured to discharge air from the container body in an open state until the interior of the container body is in the negative pressure state, and change from the open state to a closed state after the sewage passes into the interior of the container body; and a gravity sewage unloading assembly, located at a bottom of the container body and configured to close the discharging port of the container body in a normally closed state, and change from the normally closed state to an open state under an action of gravity of the sewage, so as to discharge the sewage from the discharging port.

Description

TECHNICAL FIELD

The present disclosure relates to a field of environmental sanitation technical, and in particular, to a device and a method for drafting air in field and in-situ unloading sewage based on gravity, and a system and a method for discharging suction sewage.

BACKGROUND

A suction sewage discharging, sometimes referred to as an indoor vacuum sewage discharging, a vacuum source separation sewage discharging, or a negative pressure source separation sewage discharging, which is a sanitary discharging manner in which a sanitary ware such as a toilet is connected to a suction pipeline, and is mainly applied in an environmental sanitation system for implementing a high-concentration discharging and collection of sanitary wastewater. The "sanitary wastewater" here refers specifically to wastewater used for discharging sanitary wastes, and the sanitary wastes include excrement, urine and kitchen wastes, but do not include washing wastewater such as bathing, laundry, and kitchen rinsing. The "suction sewage discharging" here includes a process of transferring sanitary wastewater from a sanitary ware to a location of storage, discharging or treatment and utilization, but does not include a process of storage, discharging or treatment and utilization. When an intensity of pressure in the suction pipeline is lower than an external atmospheric pressure, the sanitary ware is connected to the suction pipeline, such that the sanitary wastewater in the sanitary ware is sucked into the suction pipeline and transported to a far end, so as to implement a discharging function of sanitary wastewater. Compared with the water-flushing sanitary discharging manner relying on a hydraulic gravity to implement a pipeline transportation, the suction sewage discharging has advantages of water saving, energy saving and consumption reduction, may particularly implement a low-dilution collection of sanitary wastes such as excrement and urine, and has created favorable conditions for subsequent resource treatment and utilization.

SUMMARY

In view of this, the main object of the present disclosure is to provide a device and a method for drafting air in field and in-situ unloading sewage based on gravity, and a system and a method for discharging suction sewage.
In order to achieve the above object, the technical solutions of the present disclosure are as follows.
According to an aspect of the present disclosure, there is provided a device for drafting air in field and unloading sewage based on gravity, including: a container body including a feeding port and a discharging port, wherein the feeding port is configured to allow a sewage to pass into an interior of the container body when the interior of the container body is in a negative pressure state; an air drafting assembly, located at a top of the container body and configured to discharge air from the container body in an open state until the interior of the container body is in the negative pressure state, and change from the open state to a closed state after the sewage passes into the interior of the container body; and a gravity sewage unloading assembly, located at a bottom of the container body and configured to close the discharging port of the container body in a normally closed state, and change from the normally closed state to an open state under an action of gravity of the sewage, so as to discharge the sewage from the discharging port.
According another aspect of the present disclosure, there is provided a method for drafting air in field and unloading sewage based on gravity using the device as described above, including: opening an air drafting assembly until an interior of a container body is in a negative pressure state, when a gravity sewage unloading assembly is in a normally closed state; sucking a sewage into the interior of the container body via a feeding port of the container body in the negative pressure state; changing the gravity sewage unloading assembly from the normally closed state to an open state under an action of gravity of the sewage after closing the air drafting assembly; and discharging the sewage from a discharging port of the container body when the gravity sewage unloading assembly is in the open state.
According to another aspect of the present disclosure, there is provided a system for discharging suction sewage based on drafting air in field and unloading sewage based on gravity, including: a device for drafting air in field and unloading sewage based on gravity, including: a container body including a feeding port and a discharging port, wherein the feeding port is configured to allow a sewage to pass into an interior of the container body when the interior of the container body is in a negative pressure state; an air drafting assembly, located at a top of the container body and configured to discharge air from the container body in an open state until the interior of the container body is in the negative pressure state; and a gravity sewage unloading assembly, located at a bottom of the container body and configured to close the discharging port of the container body in a normally closed state, and change from the normally closed state to an open state under an action of gravity of the sewage, so as to discharge the sewage from the discharging port; and a sewage discharging apparatus, connected to the feeding port of the device, and configured to discharge the sewage to the feeding port of the device.
According to another aspect of the present disclosure, there is provided a method for discharging suction sewage using the system as described above, including: discharging a sewage to a feeding port of a container body using a sewage discharging apparatus when a gravity sewage unloading assembly is in a normally closed state, and simultaneously opening an air drafting assembly until an interior of the container body is in a negative pressure state; sucking the sewage into the interior of the container body via the feeding port in the negative pressure state; changing the gravity sewage unloading assembly from the normally closed state to an open state under an action of gravity of the sewage, after closing the air drafting assembly; and discharging the sewage from a discharging port of the container body when the gravity sewage unloading assembly is in the open state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic structure diagram of a device for drafting air in field and uploading sewage based on gravity according to the embodiments of the present disclosure;
FIG. 2 shows a schematic flow diagram of a method for drafting air in field and uploading sewage based on gravity according to the embodiments of the present disclosure;
FIG. 3 shows a schematic structure diagram of a system for discharging suction sewage based on drafting air in field and uploading sewage based on gravity according to the embodiments of the present disclosure; and
FIG. 4 shows a schematic flow diagram of a method for discharging suction sewage based on drafting air in field and uploading sewage based on gravity according to the embodiments of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

In order to make the objectives, technical solutions and advantages of the present disclosure more clear and explicit, the present disclosure will be further described in detail below with reference to the specific embodiments and the accompanying drawings.
In the related technologies of suction sewage discharging, it is usually necessary to construct a suction pipeline system composed of a suction pipeline, a storage container, an interface valve, a vacuum pump, etc. The intensity of pressure in the suction pipeline system is normally lower than an external atmospheric pressure, i.e., it maintains in a vacuum degree or a negative pressure state, wherein the interface valve and the vacuum pump are respectively located at a boundary position between the suction pipeline system and the external atmospheric pressure, and the vacuum pump also provides a power to forcibly discharge a gas and the like inside the suction pipeline out of the suction pipeline system, so as to maintain the intensity of pressure in the system lower than the atmospheric pressure. The suction pipeline system has the following characteristics: (1) maintaining the vacuum degree or negative pressure state has a high requirement on sealing, and if an air leakage occurs, the energy will be wasted in a lesser case, and the system will fail in a severe case; and (2) sanitary wastewater goes from a sanitary ware in an atmospheric pressure environment directly to a storage, treatment or utilization facility in the atmospheric pressure environment, and only passes through the suction pipeline system in a negative pressure environment during this process, and thus additional measurements are required to transfer the sanitary wastewater from the negative pressure environment to the atmospheric pressure environment, for example, breaking the negative pressure or using a high-lift sewage discharging pump to forcibly discharge the sanitary wastewater in the suction pipeline. This has caused several deficiencies in the practical application of the suction sewage discharging technology as followings: (1) the requirement on a vacuum pump station is relatively high, which increases the costs of constructing and operating of the pump station; (2) the sealing requirement on the suction pipeline is relatively high, which increases the costs of laying and maintaining the pipeline; (3) a sanitary ware at a user end needs to be connected to the suction pipeline through a specially-made sewage discharging interface valve, and this often results in a need to use a specially-made sanitary ware at the user end; and (4) since a relatively high negative pressure is generally maintained in the suction pipeline, a loud suction noise will be generated at the moment when the sewage discharging interface valve is opened at the user end, which will affect a user experience. When the above suction sewage discharging technology is applied to a scenario such as rural sanitation, the costs of centralizedly set pump stations and suction pipeline systems are particularly high due to scattered rural residences.
In the process of implementing the present disclosure, an air drafting assembly connected to the atmospheric pressure environment may be provided on a sewage discharging pipeline, so as to transfer sanitary wastewater in an indoor sanitary ware to an outdoor. The sewage discharging pipeline refers to a pipeline system connecting an indoor sanitary ware with an outdoor facility for discharging, treatment or utilization. An instantaneous negative pressure generated in the sewage discharging pipeline upon opening the air drafting assembly sucks the sanitary wastewater in the sanitary ware into the pipeline, then the air drafting assembly is closed such that the sewage discharging pipeline is restored to the atmospheric pressure, and after this the sanitary wastewater is unloaded from the sewage discharging pipeline under an action of gravity. As such an instantaneous negative pressure is used and a negative pressure state does not need to be maintained, there is no need to connect the sanitary ware with the sewage discharging pipeline through an interface valve, and thus it may be widely used in conventional sanitary wares, which may reduce the requirement on the sealing of a sewage pipeline, avoid a need to construct a pump station, reduces the costs of constructing and operating a pump station as well as laying and maintaining a pipeline, and may be applied in scattered rural residences, such as rural sanitation.
Specifically, according to the embodiments of the present disclosure, there is provided a device and a method for drafting air in field and in-situ unloading sewage based on gravity, and a system and a method for discharging suction sewage. FIG. 1 shows a schematic structure diagram of a device for drafting air in field and unloading sewage based on gravity according to the embodiments of the present disclosure. As shown in FIG. 1, a device 100 for drafting air in field and uploading sewage based on gravity according to the present disclosure includes: a container body 110 including a feeding port 111 and a discharging port 112, the feeding port 111 is configured to allow a sewage to pass into an interior of the container body 110 when the interior of the container body 110 is in a negative pressure state; an air drafting assembly 120 located at a top of the container body 110 and configured to discharge air from the container body 110 in an open state until the interior of the container body 110 is in the negative pressure state, and change from the open state to a closed state after the sewage passes into the interior of the container body 110; and a gravity sewage unloading assembly 130, located at a bottom of the container body 110 and configured to close the discharging port 112 of the container body in a normally closed state, and change from the normally closed state to an open state under an action of gravity of the sewage, so as to discharge the sewage from the discharging port 112.
According to the embodiments of the present disclosure, as the gravity sewage unloading assembly is in the normally closed state, an instantaneous negative pressure is generated after the air drafting assembly is opened and the air in the interior of the container body is discharged, the sewage is sucked from the feeding port into the container body under an action of the negative pressure, then the air drafting assembly is closed, the interior of the container body may be restored to a normal pressure, and the sewage may be discharged from the discharging port under an action of gravity through the gravity sewage unloading assembly. The suction sewage discharging manner under the instantaneous negative pressure is different from the suction sewage discharging manner under a normal state negative pressure. For one aspect, there is no need to construct a pump station, and the requirement on the sealing of a pipeline is relatively low, thereby reducing the costs of construction and maintenance. For another aspect, there is no need to provide a specially-made interface valve at the feeding port of the container body, i.e., at a sewage discharging port of the sanitary ware to maintain the normal state negative pressure. This simplifies the structure, and the suction sewage discharging manner of the present disclosure may be applied to conventional sanitary wares. For further another aspect, the gravity sewage unloading manner does not require power consumption and power equipment, which simplifies the structure and saves energy. For yet another aspect, the device for drafting air in field and uploading sewage based on gravity of the present disclosure may be set in a one-to-one correspondence with a sanitary ware, and is applicable for scenarios where residences are relatively scattered.
According to the embodiments of the present disclosure, the feeding port 111 of the container body 110 is connected to an external sewage discharging apparatus, and a liquid sealing apparatus is provided between the feeding port 111 and the sewage discharging apparatus. The sealing provided by the liquid sealing apparatus is beneficial to form a specific negative pressure state in the interior of the container body 110. The negative pressure state may be 5-30 kPa lower than the external atmospheric pressure, so that the sewage may smoothly pass into the interior of the container body 110.
In some embodiments, the sewage discharging apparatus may be, but not limited to, a sanitary ware such as a toilet and a sink; in some embodiments, the connection manner may be a pipeline connection; and in some embodiments, the liquid sealing apparatus may be, for example, a U-shaped pipeline.
According to the embodiments of the present disclosure, a volume of the container body 110 is 3-5 times a volume of a sewage passed at one time; and a shape of the container body 110 is a cuboid as shown in FIG. 1, but is not limited thereto.
According to the embodiments of the present disclosure, the air drafting assembly 120 is generally configured to be manually opened, such that the air drafting assembly 120 may be flexibly opened according to the use requirements of the sewage discharging apparatus, and it may be configured to be manually closed or automatically closed. An automatic closing manner is more convenient than a manual closing manner.
According to the embodiments of the present disclosure, the air drafting assembly 120 includes an exhaust fan and a switch circuit, wherein the switch circuit is configured to control an opening or closing of the exhaust fan. As the exhaust fan has a good ventilation performance, it is also beneficial to quickly restore the interior of the container body 110 to a normal pressure after the air drafting assembly 120 is closed, such that the sewage is quickly discharged from the discharging port 112 under the action of gravity. It may be understood that an air drafting assembly 120 of another structural form may also be used, such as a combined structure of an electric air suction pump and a switch circuit, as long as it may discharge air from the container body 110 in the open state to form a negative pressure state in the interior of the container body 110.
According to the embodiments of the present disclosure, the switch circuit is configured to control the exhaust fan to be automatically delay-closed after being opened, and a delay time is configured to allow the sewage discharged at one time to completely pass into the interior of the container body. In other words, the switch circuit at this time is a time-delay switch circuit, and the specific circuit structure may be a time-delay relay circuit or the like, but is not limited thereto.
In some embodiments, the delay time may be, for example, 0.3-1 second, and the delay time may be appropriately extended as a distance between the device for drafting air in field and uploading sewage based on gravity and the sewage discharging apparatus increases and an amount of sewage increases.
According to the embodiments of the present disclosure, the gravity sewage unloading assembly 130 includes a movable door 131 hinged on the container body 110; a counterweight 132 provided on the movable door 131, wherein the movable door 131 is abutted against the discharging port 112 of the container body 110 under an action of gravity of the counterweight 132, such that the gravity sewage unloading assembly 130 is in the normally closed state; and when the sewage overcomes the action of gravity of the counterweight 132, the movable door 131 is rotated relative to the container body 110 and is no longer abutted against the discharging port 112 of the container body 110, so that the gravity sewage unloading assembly is in the open state.
It may be understood that a gravity sewage unloading assembly 130 of another structural form may also be used, as long as it may change from the normally closed state to the open state under the action of gravity of the sewage, such that the sewage is discharged from the discharging port 112. The meaning of the "normally closed state" of the gravity sewage unloading assembly 130 includes that: the gravity sewage unloading assembly 130 may be automatically restored to a state to close the discharging port of the container body 110, after sewage is discharged from the discharging port 112.
Based on the device for drafting air in field and uploading sewage based on gravity as described above, the present disclosure further provides a method for drafting air in field and uploading sewage based on gravity. FIG. 2 shows a schematic flow diagram of a method for drafting air in field and unloading sewage based on gravity according to the embodiments of the present disclosure. As shown in FIG. 2, the method for drafting air in field and unloading sewage based on gravity according to the present disclosure includes step A to step D as follows.
In step A, an air drafting assembly 120 is opened until an interior of a container body 110 is in a negative pressure state, when a gravity sewage unloading assembly 130 is in a normally closed state. Alternatively, the air drafting assembly 120 is usually configured to be manually opened, and the air drafting assembly 120 is usually opened when sewage in a sewage discharging apparatus such as a toilet needs to be discharged.
In step B, sewage is sucked into the interior of the container body 110 via a feeding port 111 of the container body 110 in the negative pressure state. Alternatively, the negative pressure state may be 5-30 kPa lower than an external atmospheric pressure, so as to facilitate a smooth passage of the sewage into the interior of the container body 110.
In step C, the gravity sewage unloading assembly 130 is changed from the normally closed state to an open state under an action of gravity of the sewage after the air drafting assembly 120 is closed. Alternatively, the air drafting assembly 120 may be configured to be manually closed, or configured to be automatically delay-closed after being opened, a delay time may be, for example, 0.3-1 second, and the delay time may be appropriately extended as a distance between the device for drafting air in field and uploading sewage based on gravity and the sewage discharging apparatus increases and an amount of sewage increases.
In step D, the sewage is discharged from a discharging port 112 of the container body 110 when the gravity sewage unloading assembly 130 is in the open state. It may be understood that the gravity sewage unloading assembly 130 is automatically restored to the normally closed state, after the sewage is discharged.
Based on the device for drafting air in field and uploading sewage based on gravity as described above, the present disclosure further provides a system for discharging suction sewage based on drafting air in field and unloading sewage based on gravity. FIG. 3 shows a schematic structure diagram of a system for discharging suction sewage based on drafting air in field and unloading sewage based on gravity according to the embodiments of the present disclosure. As shown in FIG. 3, the system for discharging suction sewage according to the present disclosure includes a device 100 for drafting air in field and uploading sewage based on gravity and a sewage discharging apparatus 200. The specific structure of the device 100 for drafting air in field and uploading sewage based on gravity is described in detail in the above text, and will not be repeated here. The sewage discharging apparatus 200 may be a toilet as shown in FIG. 3, and is not limited thereto, or it may also be another sanitary ware such as a sink, or another sewage discharging apparatus from which sewage needs to be discharged.
According to the embodiments of the present application, the sewage discharging apparatus 200 is a water-flushing sanitary ware, and the system for discharging suction sewage is configured to be switchable between a first sewage discharging working mode and a second sewage discharging working mode, wherein: in the first sewage discharging working mode, clean water of a first volume is used to flush the sewage discharging apparatus 200 and generate sewage, and the air drafting assembly 120 is opened such that the sewage of the sewage discharging apparatus 200 is sucked into the container body 110; in the second sewage discharging working mode, clean water of a second volume is used to flush the sewage discharging apparatus 200 and generate sewage, and the air drafting assembly 120 is not opened, and the sewage of the sewage discharging apparatus is discharged to the container body 110 through a hydraulic gravity; wherein the first volume is less than or equal to 1.5 liters/time, and the second volume is greater than or equal to 3 liters/time.
It may be understood that in the first sewage discharging working mode, only a small amount of clean water may be used to flush the sewage discharging apparatus; and the second sewage discharging working mode corresponds to a water-flushing gravity sewage discharging, and the second sewage discharging working mode may be used in the event of a failure of the device for drafting air in field and uploading sewage based on gravity to facilitate a normal sewage discharging of the sewage discharging apparatus.
According to the embodiments of the present disclosure, the sewage discharging apparatus 200 may be triggered to flush the sewage discharging apparatus 200 with the clean water of the first volume through a flush button, and the flush button may be electrically connected to the switch circuit of the air drafting assembly 120, so as to trigger an opening of the air drafting assembly 120 simultaneously.
According to the embodiments of the present disclosure, the feeding port 111 of the container body 110 is connected to the sewage discharging apparatus 200, and a liquid sealing apparatus is provided between the feeding port 111 and the sewage discharging apparatus 200. The liquid sealing apparatus, as shown in FIG. 3, may be a U-shaped pipeline. The sealing provided by the liquid sealing apparatus is beneficial to form a specific negative pressure state in the interior of the container body 110, and the negative pressure state may be 5-30 kPa lower than an external atmospheric pressure, so as to facilitate a smooth passage of the sewage into the interior of the container body 110.
According to the embodiments of the present disclosure, the system for discharging suction sewage further includes a wastewater storage tank 300 configured to receive sewage discharged from the discharging port 112 of the device 100 for drafting air in field and uploading sewage based on gravity. The wastewater storage tank 300 may be a facility for an in-situ discharging, treatment or utilization, such as a septic tank, or may be used as a transfer station, and sewage in the wastewater storage tank 300 may be further transported by means of a pipeline or a vehicle to a facility for a centralized discharging, treatment or utilization.
Optionally, as shown in FIG. 3, the discharging port 112 may extend to an interior of the wastewater storage tank 300, but is not limited thereto, and it may be also located above the wastewater storage tank 300, or connected to the wastewater storage tank 300 through a pipeline, as long as a sufficient space may be reserved such that the gravity sewage unloading assembly 130 at the discharging port 112 is moveable relative to the container body 110.
For ease of understanding, a specific description is made by taking an establishment of a system for discharging suction sewage for an in-situ discharging, treatment and utilization for a single farmer as an example. In this example, the sewage discharging apparatus 200 is a conventional water-flushing toilet provided indoors, a U-shaped pipeline is provided in this conventional water-flushing toilet as a liquid sealing apparatus, and a three-compartment septic tank is provided in-situ outdoors as the wastewater storage tank 300. For the method and technical requirements of the three-compartment septic tank, please refer to relevant technical standards. Then, the device 100 for drafting air in field and uploading sewage based on gravity is installed above the three-compartment septic tank, the feeding port of the device 100 for drafting air in field and uploading sewage based on gravity is connected to a sewage discharging port of the sewage discharging apparatus 200, and then the effluent and the swept manure from the three-compartment septic tank are applied into the own land of the farmer.
In addition, a specific description is made by taking an establishment of a system for discharging suction sewage for a centralized discharging, treatment and utilization for a village as an example. In this example, the sewage discharging apparatus of each residence is respectively provided with a device 100 for drafting air in field and uploading sewage based on gravity, the sewage discharging apparatus 200 is a conventional water-flushing toilet provided indoors, and the device 100 for drafting air in field and uploading sewage based on gravity is provided on an outer wall of a residence adjacent to the sewage discharging apparatus 200. A two-compartment septic tank is provided for each residence as the wastewater storage tank 300, and a hydraulic retention time of the first compartment of the two-compartment septic tank is 20 days, and the hydraulic retention time of the second compartment thereof is 10 days. The discharging port of the device 100 for drafting air in field and uploading sewage based on gravity is connected to the feeding port of the septic tank through a pipeline, and a hydraulic gradient of the pipeline is not less than 5%o. A centralized manure storage tank is provided outside the village, and the hydraulic retention time of the centralized manure storage tank is designed to be 30 days. The effluent from the septic tank of each residence is gravity-transported to the centralized septic tank through the pipeline, and the sewage from the centralized septic tank is regularly applied to the nearby farmland.
Based on the system for discharging suction sewage described above, the present disclosure further provides a method for discharging suction sewage based on drafting air in field and unloading sewage based on gravity. FIG. 4 shows a schematic flow diagram of a method for discharging suction sewage based on drafting air in field and unloading sewage based on gravity according to the embodiments of the present disclosure. As shown in FIG. 4, the method for discharging suction sewage includes the following steps.
Step a: sewage is discharged to a feeding port 111 of a container body 110 using a sewage discharging apparatus 200, when a gravity sewage unloading assembly 130 is in a normally closed state, and an air drafting assembly 120 is simultaneously opened until an interior of the container body 110 is in a negative pressure state.
Step b: the sewage is sucked into the interior of the container body 110 via the feeding port 111 in the negative pressure state;
Step c: the gravity sewage unloading assembly 130 is changed from the normally closed state to an open state under an action of gravity of the sewage, after the air drafting assembly 120 is closed.
Step d: the sewage is discharged from a discharging port of the container body 110, when the gravity sewage unloading assembly 130 is in the open state.
The specific embodiments above further describe the objectives, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above descriptions are only specific embodiments of the present disclosure, and are not intended to limit the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure should be included within the protection scope of the present disclosure.

Claims

A device for drafting air in field and unloading sewage based on gravity, comprising:
a container body comprising a feeding port and a discharging port, wherein the feeding port is configured to allow a sewage to pass into an interior of the container body when the interior of the container body is in a negative pressure state;

an air drafting assembly, located at a top of the container body and configured to discharge air from the container body in an open state until the interior of the container body is in the negative pressure state, and change from the open state to a closed state after the sewage passes into the interior of the container body; and

a gravity sewage unloading assembly, located at a bottom of the container body and configured to close the discharging port of the container body in a normally closed state, and change from the normally closed state to an open state under an action of gravity of the sewage, so as to discharge the sewage from the discharging port.
The device according to claim 1, wherein the feeding port is connected to a sewage discharging apparatus, and a liquid sealing apparatus is provided between the feeding port and the sewage discharging apparatus.
The device according to claim 2, wherein the liquid sealing apparatus is a U-shaped pipeline.
The device according to claim 2, wherein the negative pressure state is 5-30 kPa lower than an external atmospheric pressure.
The device according to claim 1, 2 or 4, wherein the air drafting assembly comprises:
an exhaust fan; and

a switch circuit configured to control an opening or closing of the exhaust fan.
The device according to claim 5, wherein the switch circuit is configured to control the exhaust fan to be automatically delay-closed after being opened, and a delay time is configured to allow the sewage discharged at one time to completely pass into the interior of the container body.
The device according to claim 1, wherein the gravity sewage unloading assembly comprises:
a movable door hinged on the container body; and

a counterweight provided on the movable door;

wherein the movable door is abutted against the discharging port of the container body under an action of gravity of the counterweight, such that the gravity sewage unloading assembly is in the normally closed state; and when the sewage overcomes the action of gravity of the counterweight, the movable door is rotated relative to the container body and is no longer abutted against the discharging port of the container body, so that the gravity sewage unloading assembly is in the open state.
The device according to claim 1, wherein a volume of the container body is 3-5 times a volume of the sewage passed at one time.
A method for drafting air in field and unloading sewage based on gravity using the device according to anyone of claims 1-8, comprising:
opening an air drafting assembly until an interior of a container body is in a negative pressure state, when a gravity sewage unloading assembly is in a normally closed state;

sucking a sewage into the interior of the container body via a feeding port of the container body in the negative pressure state;

changing the gravity sewage unloading assembly from the normally closed state to an open state under an action of gravity of the sewage after closing the air drafting assembly; and

discharging the sewage from a discharging port of the container body when the gravity sewage unloading assembly is in the open state.
A system for discharging suction sewage based on drafting air in field and unloading sewage based on gravity, comprising:
a device for drafting air in field and unloading sewage based on gravity, comprising:
a container body comprising a feeding port and a discharging port, wherein the feeding port is configured to allow a sewage to pass into an interior of the container body when the interior of the container body is in a negative pressure state;

an air drafting assembly, located at a top of the container body and configured to discharge air from the container body in an open state until the interior of the container body is in the negative pressure state; and

a gravity sewage unloading assembly, located at a bottom of the container body and configured to close the discharging port of the container body in a normally closed state, and change from the normally closed state to an open state under an action of gravity of the sewage, so as to discharge the sewage from the discharging port; and

a sewage discharging apparatus, connected to the feeding port of the device, and configured to discharge the sewage to the feeding port of the device.
The system according to claim 10, wherein the feeding port is connected to the sewage discharging apparatus, and a liquid sealing apparatus is provided between the feeding port and the sewage discharging apparatus; and the liquid sealing apparatus is a U-shaped pipeline.
The system according to claim 10, wherein the sewage discharging apparatus is a water-flushing sanitary ware, and the system is configured to be switchable between a first sewage discharging working mode and a second sewage discharging working mode, wherein:
in the first sewage discharging working mode, a clean water of a first volume is used to flush the sewage discharging apparatus and generate a sewage, and the air drafting assembly is opened, so that the sewage of the sewage discharging apparatus is sucked into the container body;

in the second sewage discharging working mode, a clean water of a second volume is used to flush the sewage discharging apparatus and generate a sewage, the air drafting assembly is not opened, and the sewage of the sewage discharging apparatus is discharged to the container body through a hydraulic gravity;

wherein the first volume is less than or equal to 1.5 liters/time, and the second volume is greater than or equal to 3 liters/time.
The system according to claim 10, further comprising:
a wastewater storage tank, configured to receive the sewage discharged from the discharging port of the device.
A method for discharging suction sewage using the system according to anyone of claims 10-13, comprising:
discharging a sewage to a feeding port of a container body using a sewage discharging apparatus when a gravity sewage unloading assembly is in a normally closed state, and simultaneously opening an air drafting assembly until an interior of the container body is in a negative pressure state;

sucking the sewage into the interior of the container body via the feeding port in the negative pressure state;

changing the gravity sewage unloading assembly from the normally closed state to an open state under an action of gravity of the sewage, after closing the air drafting assembly; and

discharging the sewage from a discharging port of the container body when the gravity sewage unloading assembly is in the open state.