Septic tank gas monitoring robot

Abstract

The utility model belongs to the technical field of monitoring, and particularly relates to a septic tank gas monitoring robot which comprises a robot body, a controller, a sampling device, a concentration detection module, a concentration adjusting device, an alarm module, a network communication module, a cloud server and a remote monitoring server. The sampling device, the concentration detection module, the concentration adjusting device, the alarm module and the network communication module are electrically connected with the controller; the sampling device is used for collecting harmful gas; the concentration detection module detects the concentration of the harmful gas; the concentration adjusting device comprises an exhaust fan and a biological stock solution dispenser, and the exhaust fan and the biological stock solution dispenser are both electrically connected with the controller; the control module is used for controlling starting and stopping of the alarm module, the exhaust fan and the biological stock solution dispenser according to the gas concentration signal; the remote monitoring server is also used for sending the gas concentration signal to the cloud server through the network communication module, and the controller and the remote monitoring server perform data transmission through the cloud server, so that the concentration of harmful gas can be reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of monitoring, and in particular relates to a septic tank gas monitoring robot. Background Art

[0002] The dangers of septic tank operations mainly come from excessively high concentrations of harmful gases or extreme lack of oxygen in the tank, which can cause poisoning or even sudden death to people entering the space. The sludge deposited in the septic tank is prone to produce harmful gases such as methane, ammonia, hydrogen sulfide, and carbon monoxide. In a confined space with poor air circulation, the space is occupied by gases with a high specific gravity and the oxygen content is extremely low. After construction workers enter, they may suffocate due to lack of oxygen. When flammable gases such as methane or carbon monoxide exist in a confined space, or when painting, spraying, or using flammable and explosive solvents are carried out in it, sparks generated by welding, cutting, and other operations may cause fires or explosions. Therefore, it is extremely critical to dilute and reduce the concentration of harmful gases in the septic tank. Utility Model Content

[0003] In order to solve the above technical problems, the utility model provides a septic tank gas monitoring robot to solve the problem that the existing septic tank operation is dangerous due to the excessive concentration of harmful gases in the septic tank.

[0004] The technical solution adopted by the utility model is as follows: a septic tank gas monitoring robot, including a robot body, a controller, a sampling device, a concentration detection module, a concentration adjustment device, an alarm module, a network communication module, a cloud server and a remote monitoring server;

[0005] The sampling device, concentration detection module and concentration adjustment device are all arranged on the robot body;

[0006] The sampling device, concentration detection module, concentration adjustment device, alarm module and network communication module are all electrically connected to the controller;

[0007] The sampling device is used to collect harmful gases and transport the harmful gases to the concentration detection module;

[0008] The concentration detection module is used to detect the concentration of harmful gases, generate a gas concentration signal, and feed back the gas concentration signal to the controller;

[0009] The concentration adjustment device includes an exhaust fan and a biological stock solution dispenser, and the exhaust fan and the biological stock solution dispenser are both electrically connected to the controller and are both arranged on the robot body;

[0010] The exhaust end of the exhaust fan extends into the septic tank to exhaust harmful gases;

[0011] The delivery end of the biological stock solution delivery device extends into the underground network pipe for delivering the biological stock solution;

[0012] The controller is used to control the opening and closing of the alarm module, the exhaust fan and the biological stock solution dispenser according to the gas concentration signal; it is also used to send the gas concentration signal to the cloud server through the network communication module, and the controller and the remote monitoring server transmit data through the cloud server.

[0013] Furthermore, it also includes a display and a control button, both of which are arranged on the robot body, and the display is electrically connected to the controller;

[0014] The controller controls the display content of the display according to the gas concentration signal;

[0015] The exhaust fan and the biological stock solution dispenser are both electrically connected to a control button, and the control button can control the opening and closing of the exhaust fan and the biological stock solution dispenser.

[0016] Furthermore, it also includes a low-altitude hazard source monitoring module, which includes three first cameras, which are respectively arranged on the front, left and right side walls of the robot body head, collect hazard source image information around the robot body installation position, generate a first image signal, and feed back the first image signal to the controller;

[0017] The controller is used to control the opening and closing of the alarm module according to the first image signal; it is also used to send the first image signal to the cloud server through the network communication module, and the controller and the remote monitoring server perform data transmission through the cloud server.

[0018] Furthermore, the sampling device includes a vacuum pump, a dryer and an air circuit switch. The vacuum pump is used to draw harmful gases from the septic tank into the dryer. The dryer is connected to the concentration detection module through the air circuit switch. The air circuit switch is used to transport the harmful gases in the dryer to the concentration detection module. The vacuum pump and the air circuit switch are electrically connected to the controller.

[0019] Furthermore, the concentration detection module includes a methane sensor, a carbon monoxide sensor, a hydrogen sulfide sensor and an ammonia sensor, and the methane sensor, the carbon monoxide sensor, the hydrogen sulfide sensor and the ammonia sensor are all electrically connected to the controller.

[0020] Furthermore, the methane sensor is an infrared sensor; the carbon monoxide sensor, the hydrogen sulfide sensor and the ammonia sensor are all electrochemical sensors.

[0021] Furthermore, it also includes a temperature sensor, which is arranged on the robot body, detects the ambient temperature of the installation position of the robot body, generates a temperature detection signal, and feeds back the temperature detection signal to the controller.

[0022] Furthermore, an anti-theft device is included, the anti-theft device includes a mounting frame, a second camera and a prompter, the mounting frame is arranged on one side of the robot body, the second camera is arranged on the mounting frame, and the second camera is electrically connected to the controller;

[0023] The second camera collects image information of the installation position of the robot body, generates a second image signal, and feeds back the second image signal to the controller;

[0024] The controller is used to control the opening and closing of the prompter according to the second image signal; it is also used to send the second image signal to the cloud server through the network communication module, and the controller and the remote monitoring server transmit data through the cloud server.

[0025] Furthermore, it also includes a liquid level sensor, which is arranged in the septic tank and is used to detect the liquid level height of the sewage in the septic tank.

[0026] Beneficial effects of the utility model:

[0027] The monitoring personnel can remotely monitor the server to access the server, start the sampling device through the controller to collect harmful gases, and transport the harmful gases to the concentration detection module, enter the concentration detection module, detect the concentration of harmful gases, generate gas concentration signals, and feed back the gas concentration signals to the controller. The controller controls the alarm module, the exhaust fan and the biological stock solution dispenser according to the gas concentration signal. When the gas concentration exceeds the preset concentration range, the controller controls the alarm module to alarm, and the controller starts the exhaust fan to extract the gas in the septic tank to achieve the purpose of reducing the concentration of harmful gases. At the same time, by starting the biological stock solution dispenser, biological stock solution is added into the septic tank to degrade harmful gases, thereby reducing the concentration of harmful gases in the detection environment. The controller is also used to send the gas concentration signal to the cloud server through the network communication module. The controller and the remote monitoring server transmit data through the cloud server, which is convenient for the monitoring personnel to monitor the concentration of harmful gases in real time and perform remote operations, which greatly improves the intelligence of the septic tank monitoring robot and effectively avoids dangerous situations in the septic tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a signal flow diagram of the utility model; DETAILED DESCRIPTION

[0029] The following is a further detailed description of the implementation of the present invention in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0030] In the description of the present invention, unless otherwise specified, "multiple" means two or more; the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0031] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Example

[0033] like Figure 1 As shown, a septic tank gas monitoring robot includes a robot body, a controller, a sampling device, a concentration detection module, a concentration adjustment device, an alarm module, a network communication module, a cloud server and a remote monitoring server; in this embodiment, the controller is a single-chip microcomputer, preferably a STM32H series high-performance single-chip microcomputer; the alarm module adopts a voice sound and light alarm of Taichuang (home appliances), model TCSG-110; the network communication module is GPRS to realize wireless transmission, realize the networking of the monitoring system, and is used to access the Internet through a router and the like to realize the connection with the server, upload the detection information to the urban sewage pipe network safety monitoring system in real time, and realize information interaction; the remote monitoring server is a computer;

[0034] The sampling device, concentration detection module and concentration adjustment device are all arranged on the robot body;

[0035] The sampling device, concentration detection module, concentration adjustment device, alarm module and network communication module are all electrically connected to the controller;

[0036] The sampling device is used to collect harmful gases and transport the harmful gases to the concentration detection module;

[0037] The concentration detection module is used to detect the concentration of harmful gases, generate a gas concentration signal, and feed back the gas concentration signal to the controller;

[0038] The concentration adjustment device includes an exhaust fan and a biological stock solution dispenser, and the exhaust fan and the biological stock solution dispenser are both electrically connected to the controller and are both arranged on the robot body;

[0039] The exhaust end of the exhaust fan extends into the septic tank to exhaust harmful gases;

[0040] The delivery end of the biological stock solution delivery device extends into the underground network pipe for delivering the biological stock solution;

[0041] The controller is used to control the opening and closing of the alarm module, the exhaust fan and the biological stock solution dispenser according to the gas concentration signal; it is also used to send the gas concentration signal to the cloud server through the network communication module, and the controller and the remote monitoring server transmit data through the cloud server.

[0042] As a preferred solution, it also includes a display and a control button, both of which are arranged on the robot body, and the display is electrically connected to the controller;

[0043] The controller controls the display content of the display according to the gas concentration signal;

[0044] The exhaust fan and the biological stock solution dispenser are both electrically connected to a control button, and the control button can control the opening and closing of the exhaust fan and the biological stock solution dispenser.

[0045] By setting a display on the robot head, the controller can control the display to display the gas concentration according to the gas concentration signal, so that the on-site operator can check the gas concentration in real time, and by setting control buttons on the robot body, the on-site operator can control the opening and closing of the exhaust fan and the biological stock solution dispenser through the control buttons on the robot body. When the gas concentration exceeds the preset concentration range, the exhaust fan is started to extract the gas in the septic tank to achieve the purpose of reducing the concentration of harmful gases. By starting the biological stock solution dispenser, the biological stock solution is added into the septic tank to degrade the harmful gas. In this embodiment, the liquid outlet of the biological stock solution dispenser is connected to the delivery pipe and the delivery pipe is extended into the septic tank, thereby degrading the harmful gas. The biological stock solution is a biological strain. In this embodiment, the biological strain is a composite probiotic, and the type is XZ8805 septic tank special strain.

[0046] In this embodiment, the display is also used to display city intelligence publicity.

[0047] As a preferred solution, it also includes a low-altitude hazard source monitoring module, which includes three first cameras, which are respectively arranged on the front, left and right side walls of the robot body head, collect hazard source image information around the robot body installation position, generate a first image signal, and feed back the first image signal to the controller;

[0048] The controller is used to control the opening and closing of the alarm module according to the first image signal; it is also used to send the first image signal to the cloud server through the network communication module, and the controller and the remote monitoring server perform data transmission through the cloud server.

[0049] By arranging the first cameras on the front, left and right side walls of the robot body head for video monitoring, surrounding dangerous sources can be monitored in real time and low-altitude supervision can be carried out to avoid fire or explosion.

[0050] In this embodiment, there are "No Fireworks" signs on both sides of the robot's arms, supplemented by light indications, to avoid fire or explosion.

[0051] As a preferred embodiment, the sampling device includes a vacuum pump, a dryer and an air circuit switch. The vacuum pump is used to draw harmful gases from the septic tank into the dryer. The dryer is connected to the concentration detection module through the air circuit switch. The air circuit switch is used to transport the harmful gases in the dryer to the concentration detection module. The vacuum pump and the air circuit switch are electrically connected to the controller.

[0052] In the present embodiment, the dryer comprises a dry closed chamber, a dry air inlet, a dry air outlet and a desiccant, wherein the dry air inlet and the dry air outlet are provided on the dry closed chamber, and the desiccant is arranged in the dry closed chamber; the suction end of the vacuum pump is placed in the septic tank, and the air outlet end of the vacuum pump is connected with the dry air inlet of the dry closed chamber, and the vacuum pump draws harmful gases from the septic tank into the dry closed chamber, and the desiccant adopts color-changing silica gel, and after the harmful gases are dried and impurities are removed by the desiccant, the harmful gases in the dry closed chamber are transported to the concentration detection module through the air circuit switcher, and the air inlet of the air circuit switcher is connected with the dry air outlet of the dry closed chamber, and the air circuit switcher adopts a solenoid valve, which has an air inlet end and an air outlet end, and is switched by the working state of the battery valve, and the solenoid valve is electrically connected to the controller; The sampling power source adopts a vacuum pump, which has good airtightness and will not produce large vibration and noise, ensuring stable and reliable operation of the equipment. In this embodiment, the vacuum pump adopts a pump-suction variable-cycle gas sampling method, and the instrument is installed away from the site to avoid corrosion and flooding. The variable cycle means that the gas sampling cycle is variable. Specifically, the normal sampling cycle is 15 minutes. When the concentration exceeds the limit and an alarm is issued or the remote monitoring server changes the parameters, the sampling cycle is changed to 8 minutes, which can ensure the sampling frequency while reducing the system power consumption.

[0053] As a preferred solution, the concentration detection module includes a methane sensor, a carbon monoxide sensor, a hydrogen sulfide sensor and an ammonia sensor, and the methane sensor, the carbon monoxide sensor, the hydrogen sulfide sensor and the ammonia sensor are all electrically connected to the controller.

[0054] The methane sensor is used to detect the concentration of methane gas in harmful gases, generate a methane concentration signal, and feed back the methane concentration signal to the controller; the controller controls the opening and closing of the alarm module, the exhaust fan and the biological stock solution dispenser according to the methane concentration signal;

[0055] The carbon monoxide sensor is used to detect the concentration of carbon monoxide gas in harmful gases, generate a carbon monoxide concentration signal, and feed back the carbon monoxide concentration signal to the controller; the controller controls the opening and closing of the alarm module, the exhaust fan and the biological stock solution dispenser according to the carbon monoxide concentration signal;

[0056] The hydrogen sulfide sensor is used to detect the concentration of hydrogen sulfide gas in harmful gases, generate a hydrogen sulfide concentration signal, and feed back the hydrogen sulfide concentration signal to the controller; the controller controls the opening and closing of the alarm module, the exhaust fan and the biological stock solution dispenser according to the hydrogen sulfide concentration signal;

[0057] The ammonia sensor is used to detect the concentration of ammonia in harmful gases, generate an ammonia concentration signal, and feed back the ammonia concentration signal to the controller; the controller controls the opening and closing of the alarm module, the exhaust fan and the biological stock solution dispenser according to the ammonia concentration signal.

[0058] When the concentrations of methane, ammonia, hydrogen sulfide and carbon monoxide exceed the set concentration range, the controller will control the alarm module to send an alarm signal, and simultaneously turn on the exhaust fan and the biological stock solution dispenser, thereby reducing the concentrations of methane, ammonia, hydrogen sulfide and carbon monoxide in the detection environment.

[0059] As a preferred solution, the methane sensor adopts an infrared sensor; the carbon monoxide sensor, hydrogen sulfide sensor and ammonia sensor all adopt electrochemical sensors. The methane sensor adopts an infrared sensor, model JW-05, which specifically calculates the methane gas concentration through infrared absorption spectrum, with high accuracy, long adjustment cycle, long life, low maintenance, and built-in temperature compensation; the carbon monoxide sensor, hydrogen sulfide sensor and ammonia sensor all adopt electrochemical sensors, which have high sensitivity, strong interchangeability and low maintenance; the concentrations of carbon monoxide, hydrogen sulfide gas and ammonia are calculated by generating analog voltage through electrochemical reaction, the carbon monoxide sensor model is MQ2-CO-φ14X14, the hydrogen sulfide sensor model is FST100-G107-S, and the ammonia sensor model is MQ-E3-NH3.

[0060] As a preferred solution, a temperature sensor is also included. The temperature sensor is arranged on the robot body, detects the ambient temperature of the robot body installation position, generates a temperature detection signal, and feeds back the temperature detection signal to the controller. The ambient temperature of the robot body installation position is detected by the temperature sensor to avoid excessively high ambient temperature and potential safety hazards of fire. The temperature sensor is a temperature probe temperature sensor of Shanghai Feilong, model WZP-330-9.

[0061] As a preferred solution, an anti-theft device is further included, the anti-theft device comprising a mounting frame, a second camera and a prompter, the mounting frame is arranged on one side of the robot body, the second camera is arranged on the mounting frame, and the second camera is electrically connected to the controller;

[0062] The second camera collects image information of the installation position of the robot body, generates a second image signal, and feeds back the second image signal to the controller;

[0063] The controller is used to control the opening and closing of the prompter according to the second image signal; it is also used to send the second image signal to the cloud server through the network communication module, and the controller and the remote monitoring server transmit data through the cloud server.

[0064] The robot body is monitored by setting a second camera on one side of the robot body to prevent the robot body from being stolen. The second camera collects image information of the installation position of the robot body, generates a second image signal, and feeds back the second image signal to the controller; the controller controls the opening and closing of the prompter according to the second image signal. In this embodiment, the prompter is a speaker. When the robot body is stolen, the controller controls the speaker to alarm and prompt the monitoring personnel to deal with it in time. The brand of the speaker is QQCHINAPA and the model is LTH-904.

[0065] In this embodiment, the anti-theft device also includes a manhole cover anti-theft module, which includes an angle sensor. The angle sensor is electrically connected to the controller. The locking status of the manhole cover is detected by the angle sensor. When the manhole cover body is opened and is in a state of a certain inclination angle, the angle sensor senses that the manhole cover body is in an open state. At this time, the controller controls the alarm module to turn on.

[0066] As a preferred solution, a liquid level sensor is also included, which is arranged in the septic tank to detect the liquid level height of the sewage in the septic tank. By setting the liquid level sensor, the liquid level in the septic tank can be monitored to avoid the liquid level exceeding the limit and causing safety hazards. In this embodiment, the brand of the liquid level sensor is BXUAN and the model is M18.

[0067] The working mode of the utility model is as follows:

[0068] When in use, the monitoring personnel can remotely monitor the server computer to access the server, and start the vacuum pump through the controller to suck the mixed gas in the monitored environment into the dryer. The mixed gas is dried and impurities removed by the dryer and then enters the concentration detection module. The methane gas concentration is calculated through the infrared absorption spectrum of the infrared sensor, and the concentration of carbon monoxide, hydrogen sulfide gas and ammonia is calculated through the electrochemical sensor using the electrochemical reaction to generate analog voltage. When the gas concentration exceeds the preset concentration range, the controller starts the exhaust fan to extract the gas in the septic tank to achieve the purpose of reducing the concentration of harmful gases. At the same time, by starting the biological stock solution dispenser, biological stock solution is added into the septic tank to degrade harmful gases, thereby reducing the concentration of methane gas, carbon monoxide, hydrogen sulfide gas and ammonia in the detection environment;

[0069] The on-site operator sets a display on the robot head, and the controller can control the display to display the gas concentration according to the gas concentration signal, so that the on-site operator can check the gas concentration in real time. By setting control buttons on the robot body, the on-site operator can control the opening and closing of the exhaust fan and the biological stock solution dispenser through the control buttons on the robot body.

[0070] At the same time, the utility model can also detect the ambient temperature, prevent the manhole cover from being stolen, prevent theft itself and sewage overflow, etc. The utility model also provides a GPRS wireless communication module to upload the detection information to the urban sewage pipe network security monitoring system in real time and realize information interaction.

[0071] When installing the robot body, the holes under the two legs at the bottom of the robot body are connected and fastened to the pre-prepared ground cage, and all pipelines and pipe networks enter the equipment from the legs.

[0072] The utility model is described in detail above. The description of the specific embodiments is only used to help understand the method and core idea of ​​the utility model. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the utility model, the utility model can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the utility model.

Claims

1. A septic tank gas monitoring robot, characterized in that: It includes a robot body, a controller, a sampling device, a concentration detection module, a concentration adjustment device, an alarm module, a network communication module, a cloud server and a remote monitoring server; The sampling device, concentration detection module and concentration adjustment device are all arranged on the robot body; The sampling device, concentration detection module, concentration adjustment device, alarm module and network communication module are all electrically connected to the controller; The sampling device is used to collect harmful gases and transport the harmful gases to the concentration detection module; The concentration detection module is used to detect the concentration of harmful gases, generate a gas concentration signal, and feed back the gas concentration signal to the controller; The concentration adjustment device includes an exhaust fan and a biological stock solution dispenser, and the exhaust fan and the biological stock solution dispenser are both electrically connected to the controller and are both arranged on the robot body; The exhaust end of the exhaust fan extends into the septic tank to exhaust harmful gases; The delivery end of the biological stock solution delivery device extends into the underground network pipe for delivering the biological stock solution; The controller is used to control the opening and closing of the alarm module, the exhaust fan and the biological stock solution dispenser according to the gas concentration signal; it is also used to send the gas concentration signal to the cloud server through the network communication module, and the controller and the remote monitoring server transmit data through the cloud server.

2. A septic tank gas monitoring robot according to claim 1, characterized in that: It also includes a display and a control button, both of which are arranged on the robot body, and the display is electrically connected to the controller; The controller controls the display content of the display according to the gas concentration signal; The exhaust fan and the biological stock solution dispenser are both electrically connected to a control button, and the control button can control the opening and closing of the exhaust fan and the biological stock solution dispenser.

3. A septic tank gas monitoring robot according to claim 1, characterized in that: It also includes a low-altitude hazard source monitoring module, which includes three first cameras, which are respectively arranged on the front, left and right side walls of the robot body head, collect hazard source image information around the robot body installation position, generate a first image signal, and feed back the first image signal to the controller; The controller is used to control the opening and closing of the alarm module according to the first image signal; it is also used to send the first image signal to the cloud server through the network communication module, and the controller and the remote monitoring server perform data transmission through the cloud server.

4. A septic tank gas monitoring robot according to claim 1, characterized in that: The sampling device includes a vacuum pump, a dryer and an air circuit switch. The vacuum pump is used to draw harmful gases from the septic tank into the dryer. The dryer is connected to the concentration detection module through the air circuit switch. The air circuit switch is used to transport the harmful gases in the dryer to the concentration detection module. The vacuum pump and the air circuit switch are electrically connected to the controller.

5. The septic tank gas monitoring robot according to claim 1, characterized in that: The concentration detection module includes a methane sensor, a carbon monoxide sensor, a hydrogen sulfide sensor and an ammonia sensor, and the methane sensor, the carbon monoxide sensor, the hydrogen sulfide sensor and the ammonia sensor are all electrically connected to the controller.

6. A septic tank gas monitoring robot according to claim 5, characterized in that: The methane sensor is an infrared sensor; the carbon monoxide sensor, hydrogen sulfide sensor and ammonia sensor are all electrochemical sensors.

7. A septic tank gas monitoring robot according to claim 1, characterized in that: It also includes a temperature sensor, which is arranged on the robot body, detects the ambient temperature of the installation position of the robot body, generates a temperature detection signal, and feeds back the temperature detection signal to the controller.

8. The septic tank gas monitoring robot according to claim 1, characterized in that: Also includes an anti-theft device, the anti-theft device includes a mounting frame, a second camera and a prompter, the mounting frame is arranged on one side of the robot body, the second camera is arranged on the mounting frame, and the second camera is electrically connected to the controller; The second camera collects image information of the installation position of the robot body, generates a second image signal, and feeds back the second image signal to the controller; The controller is used to control the opening and closing of the prompter according to the second image signal; it is also used to send the second image signal to the cloud server through the network communication module, and the controller and the remote monitoring server transmit data through the cloud server.

9. The septic tank gas monitoring robot according to claim 1, characterized in that: It also includes a liquid level sensor, which is arranged in the septic tank and is used to detect the liquid level height of the sewage in the septic tank.

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