A device and operation method for measuring sludge bed distribution by combining sonar with remote-controlled submersible

Abstract

A device and operation method for measuring the distribution of sludge beds by combining sonar with a remotely operated vehicle (ROV), comprising a remotely operated vehicle (ROV) body, a GPS positioning module, a sonar module, a data transmission module and a hull stabilizer. The remotely operated vehicle (ROV) is equipped with a GPS positioning module and a sonar module, and the bottom sludge bed structure is measured and recorded by sonar; after the movement trajectory of the remotely operated vehicle (ROV) is preset, the movement of the remotely operated vehicle (ROV) is controlled by the GPS positioning module to ensure that the sonar can automatically measure all the sludge beds to be measured. An operation method for measuring the distribution of sludge beds by combining sonar with a remotely operated vehicle (ROV) is provided. The present invention can effectively measure the bottom sludge bed structure of sewage treatment units such as stabilization ponds, surface flow artificial wetlands and sewage secondary sedimentation tanks, has good economy and practicality, and is simple, fast and low-cost to implement.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and relates to a device for measuring sludge bed distribution by combining sonar with a remote-controlled submersible, and an operating method. Background Art

[0002] Stabilization pond is a water treatment process that utilizes the self-purification ability of water to degrade pollutants. It utilizes a pond formed by natural or artificial excavation, and after the sewage is introduced, it uses microorganisms, algae and plants in the pond to purify the sewage. It has the characteristics of low operating cost, simple maintenance and convenient operation. During the long-term operation of the stabilization pond, sludge will be deposited at the bottom, the effective volume of the pond will gradually decrease, and the operation efficiency of the stabilization pond will decrease. Therefore, it is necessary to regularly desilt the stabilization pond according to the sludge deposition.

[0003] Constructed wetlands are artificially constructed surface water treatment processes that use the synergistic effects of physics, chemistry and biology to purify water. The removal rate of organic matter in artificial wetlands can reach 80-90%, which can buffer the adverse impact of changes in water quality and water volume load during operation. Surface flow artificial wetlands are the simplest form of artificial wetlands. Sewage flows through the surface of the wetland, and the soil and plant roots are used to adsorb and degrade the sewage, which plays a role in removing pollutants. It has the characteristics of low investment, simple operation and low operating costs. During the long-term operation of artificial wetlands, sludge will be deposited at the bottom. This deposition inhibits the respiration of plant roots and causes the deterioration of effluent water quality. Therefore, it is necessary to regularly desilt the surface flow artificial wetlands according to the deposition of sludge.

[0004] The secondary sedimentation tank is one of the treatment units of the sewage treatment plant. It is usually set at the end of the biochemical reaction unit to separate the activated sludge and water by gravity. The activated sludge gradually settles to the bottom of the secondary sedimentation tank under the action of gravity, and then part of it is returned to the biochemical reaction unit by the sludge pump, and part of it is discharged as residual sludge. When the secondary sedimentation tank is not designed properly or the sludge is not completely settled, sludge backmixing and other phenomena will occur, resulting in incomplete separation of mud and water. A large amount of activated sludge will be discharged with the effluent, affecting the effluent quality of the sewage treatment plant, and it needs to be optimized and transformed.

[0005] In summary, the formation state of the sludge layer in sewage treatment units such as stabilization ponds, surface flow artificial wetlands and sewage secondary sedimentation tanks is of great significance to the operation of the process. However, existing studies have shown that in sewage treatment units such as stabilization ponds, surface flow artificial wetlands and sewage secondary sedimentation tanks, due to the influence of hydraulic conditions, heterogeneous sedimentation and treatment unit configuration, the sludge bed structure formed is quite different from the theoretical one. Therefore, it is necessary to optimize the process by actually measuring the sludge bed structure to ensure efficient and stable operation.

[0006] Traditional operation uses a multi-point "pole insertion" method to determine the depth of the sludge bed. That is, a bamboo pole is inserted into the bottom of the structure, and the sludge bed depth is determined by the sludge marks left on the bamboo pole; or a hollow transparent plexiglass tube with openings at both ends is inserted into the bottom of the pool, and one end is closed and raised to the surface of the water, and the sludge bed depth is determined by measuring the sludge marks in the tube. These methods are not only low in accuracy, but also require high manpower consumption when the measurement unit area is large, and the detection cost is high. Therefore, it is of practical significance to develop a measurement method that can effectively measure the sludge bed structure at the bottom of sewage treatment units such as stabilization ponds, surface flow artificial wetlands, and sewage secondary sedimentation tanks, and has good economy and practicality.

[0007] Stabilization ponds, surface flow artificial wetlands and sewage secondary sedimentation tanks are all non-powered or micro-powered sewage treatment units, and mud and water separation will occur inside them due to low hydraulic disturbance. In the operation of stabilization ponds, surface flow artificial wetlands and sewage secondary sedimentation tanks, the formation state of the sludge layer is of great significance to the operation of their processes. Due to the influence of hydraulic conditions, heterogeneous sedimentation and treatment unit configuration, the formed sludge bed structure is quite different from the theory, so it is necessary to optimize the process by actually measuring the sludge bed structure to ensure efficient and stable operation.

[0008] Existing studies have shown that in sewage treatment units such as stabilization ponds, surface flow artificial wetlands and sewage secondary sedimentation tanks, the sludge bed structure formed is quite different from the theoretical one due to the influence of hydraulic conditions, heterogeneous sedimentation and the configuration of the treatment unit. Therefore, it is necessary to optimize the process by actually measuring the sludge bed structure to ensure efficient and stable operation. However, the traditional single-point "insertion rod" measurement has low accuracy, is time-consuming and costly. Summary of the invention

[0009] In order to overcome the shortcomings of the prior art of low measurement accuracy, long time consumption and high cost, the present invention provides a device and operation method for measuring sludge bed distribution by combining sonar with a remote-controlled submersible with high measurement accuracy, short time consumption and low cost.

[0010] The technical solution adopted by the present invention to solve its technical problem is:

[0011] A device for measuring the distribution of a sludge bed by combining sonar with a remote-controlled submersible comprises a remote-controlled submersible body, a GPS positioning module, a sonar module and a data transmission module. The remote-controlled submersible body is equipped with the GPS positioning module and the sonar module, and the sonar is used to measure and record the bottom sludge bed structure. After the movement trajectory of the remote-controlled submersible is preset, the GPS positioning module is used to control the movement of the remote-controlled submersible to ensure that the sonar can measure the entire bottom range. The data transmission module is used to control the engine of the remote-controlled submersible.

[0012] Furthermore, the main body of the submersible (ROV) is composed of a hull, an engine, a propeller, and a rechargeable lithium battery. The hull is 60-100 cm long, 30-50 cm wide, and has a maximum draft of 15-20 cm. The hull is injection molded using an engineering plastic mold, and fixing clamps are pre-installed on the bow and both sides of the hull. The hull has a sealed top cover to prevent rain or water splashing into the cabin; the engine adopts a DC permanent magnet motor with a voltage of 12V, a power of 30-50W, and a maximum speed of 3000-4000 rpm; a dual engine is used to control a dual propeller, the propeller is installed at the tail of the hull, the propeller is connected to the engine through a shaft, and the forward, backward, and steering of the hull are controlled by adjusting the speeds of the two sets of propellers respectively; the voltage of the rechargeable lithium battery is 12V, and the battery capacity is 30-50Ah. The rechargeable lithium battery is installed in the middle of the hull to power the equipment in the remotely controlled submersible (ROV).

[0013] Furthermore, the GPS positioning module is used for positioning the remote controlled submersible (ROV) and setting the running track. By analyzing the waters to be measured, the running route of the remote controlled submersible (ROV) is designed in advance, and various waypoints (waypoints) are set according to the route. The remote controlled submersible (ROV) is navigated by the GPS positioning module to navigate to each waypoint in turn. Each waypoint constitutes the running route, so that the submersible (ROV) can gradually complete the measurement of all waters.

[0014] The sonar module includes a sonar host and a full-scan sonar probe. The sonar is powered by 12V. The sonar host must have a 3D stereo imaging function with a frequency of 455 / 800KHz and a minimum detection depth of no more than 1.0m. The full-scan sonar probe is installed at the bottom of the bow through a fixing fixture at the bow, away from the propeller to avoid interference.

[0015] The data transmission module is connected to the handheld remote control terminal via wireless signals, so that the operator can manually take over the remotely operated vehicle (ROV) when necessary.

[0016] The device also includes a hull stabilizer, which is two identical engineering plastic injection-molded cone barrels, which are connected to pre-installed fixing clamps on both sides of the submersible (ROV) hull through aluminum alloy profiles to increase the stability of the hull in the water. The length of the cone barrel stabilizer is 40-60% of the total length of the hull, and the cone barrel diameter is 5-10 cm.

[0017] The preset submersible (ROV) route adopts zigzag reciprocating navigation and ensures that the sonar can fully cover the bottom of the water area. The interval between two parallel adjacent routes should not be greater than the maximum route interval L, but should not be too small to avoid increasing the measurement workload.

[0018] The maximum route interval L is calculated using the following formula:

[0019]

[0020] in:

[0021] L: the maximum allowable interval between adjacent routes, in meters;

[0022] H: water depth, in m;

[0023] α: beam angle, when the sonar measurement frequency is 455KHz, α=50°; when the sonar measurement frequency is 800KHz, α=20°;

[0024] k: safety factor, k=0.8.

[0025] An operating method for measuring sludge bed distribution by combining sonar with a remotely operated submersible, the method comprising the following steps:

[0026] (1) Design waypoints according to the actual conditions of the waters to be measured: calculate the maximum interval L of the route, and reasonably preset waypoints through GPS positioning. Each waypoint sequentially constitutes the preset running trajectory of the ROV to ensure that the ROV can measure the bottom of all waters. The forward speed of the remotely operated vehicle (ROV) is controlled at 2-4 km / h to ensure the accuracy of sonar data;

[0027] (2) After the waypoint setting is completed, the ROV is started, guided by GPS to the initial waypoint and the sonar measurement is started. The 3D stereo imaging sonar can penetrate to the surface of the mud layer at the bottom of the water area and record the mud layer structure in the sonar's own storage system;

[0028] (3) The ROV passes through all preset waypoints in sequence, completes the record of the mud layer structure at the bottom of the water area, and finally returns;

[0029] (4) Using 3D stereo imaging sonar combined with GPS, we can obtain three sets of data (X i , Y i , Z i ), where X i , Y i Represents longitude and latitude respectively, Z i Represents the water depth from the water surface to the sludge layer at the location; the actual depth of the structure minus Z i You can get the longitude and latitude (X i , Y i ) point;

[0030] (5) After combining the data of each point, the 3D structure of the sludge bed at the bottom of the entire water area is obtained.

[0031] The technical concept of the present invention is that the sonar system can detect underwater landforms and objects using the principle of echo sounding, which greatly reduces the difficulty of underwater detection. With the development of sonar technology, the method of using multi-beam sonar to measure and construct a three-dimensional terrain vector model has begun to be applied. 3D stereo imaging sonar can generate a multi-point array of beams from each sound wave transmission to form a complete three-dimensional model, thereby accurately mapping complex underwater structures.

[0032] The device for measuring the distribution of the sludge bed by combining sonar with a remotely operated vehicle (ROV) includes a remotely operated vehicle (ROV) body, a GPS positioning module, a sonar module, a data transmission module and a hull stabilizer. The remotely operated vehicle (ROV) is equipped with a GPS positioning module and a sonar module, and uses sonar to measure and record the bottom sludge bed structure. After the movement trajectory of the remotely operated vehicle (ROV) is preset, the GPS positioning module is used to control the movement of the remotely operated vehicle (ROV) to ensure that the sonar can measure the entire bottom range. The present invention can effectively measure the bottom sludge bed structure of sewage treatment units such as stabilization ponds, surface flow artificial wetlands and sewage secondary sedimentation tanks, has good economy and practicality, and is simple, fast and low-cost to implement.

[0033] The existing multi-beam sonar measurement technology is used to build a complete three-dimensional model to accurately map complex underwater structures. The sludge bed structure is constructed through sonar measurement to solve the problems of low accuracy, long time consumption and high labor cost of "rod" measurement. At the same time, the GPS positioning module is used to achieve fully automated measurement and further reduce operating costs.

[0034] The beneficial effects of the present invention are mainly manifested in: (1) the use of multi-beam 3D stereo imaging sonar increases measurement accuracy and improves measurement efficiency; (2) the use of a GPS positioning module to control the movement of a remotely operated vehicle (ROV) realizes automation of operation and further reduces operating costs. In summary, the present invention can effectively measure the sludge bed structure at the bottom of sewage treatment units such as stabilization ponds, surface flow artificial wetlands, and sewage secondary sedimentation tanks, has good economy and practicality, and is simple, fast, and low-cost to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the appearance and structure of a sonar combined with a remote-controlled submersible device.

[0036] Figure 2 It is a schematic diagram of the internal structure of a sonar combined with a remote-controlled submersible device.

[0037] Figure 3 It is the sludge bed structure at the bottom of a surface flow artificial wetland in Zhejiang. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings.

[0039] Reference Figure 1 to Figure 3 A device for measuring the distribution of sludge beds by combining sonar with a remotely operated vehicle (ROV), comprising a remotely operated vehicle (ROV) body, a GPS positioning module, a sonar module, a data transmission module and a hull stabilizer, etc., which is used in sewage treatment units such as stabilization ponds, surface flow artificial wetlands and sewage secondary sedimentation tanks to measure the sludge bed structure at the bottom of the structure.

[0040] Depend on Figure 1 As shown, the main body of the remotely operated submersible (ROV) consists of a hull 1, a sonar bracket 2, a propeller 3, a hull stabilizer 4, an aluminum alloy fixing bracket 5 and a sealing top cover 6. The hull is 100 cm long, 45 cm wide, and has a maximum draft of 20 cm. The hull is injection molded using an engineering plastic mold. Fixing fixtures are pre-installed on the head and both sides of the hull 1, and are connected and fixed to the hull stabilizer 4 through an aluminum alloy fixing bracket 5. The length of the aluminum alloy fixing bracket 5 is 30 cm. The hull stabilizer 4 is two identical engineering plastic injection-molded cone barrels, which are connected to the fixing fixtures pre-installed on both sides of the hull through an aluminum alloy profile to increase the stability of the hull in the water. The hull stabilizer 4 is 50 cm long and 8 cm in diameter. The hull has a sealing top cover 6 to prevent rain or water splashes from splashing into the cabin. The propeller 3 is installed at the tail of the hull, and the propeller is connected to the engine through a shaft. By adjusting the speed of the two sets of propellers respectively, the forward, backward and steering of the hull are controlled.

[0041] After opening the sealed top cover Figure 2 As shown, the interior of the remotely operated submersible (ROV) is composed of a hull base 11, a 3D sonar probe 12, a propeller 3, a hull stabilizer 4, an aluminum alloy fixing bracket 5, a sonar host 16, a rechargeable lithium battery 17, a GPS positioning module 18, a data transmission module 19, and an engine 20. The sonar module includes a sonar host 16 and a 3D sonar probe 12, which is the core component for underwater sludge bed measurement. The sonar host 16 is powered by 12V and has a 3D stereo imaging function with a frequency of 455 / 800KHz and a minimum detection depth of 0.8m. The 3D sonar probe 12 is installed at the bottom of the bow through a fixing fixture at the bow, away from the propeller 13 to avoid interference.

[0042] The voltage of the rechargeable lithium battery 17 is 12V, and the battery capacity is 30-50Ah. The rechargeable lithium battery 17 is installed in the middle of the hull to power all the equipment on the remotely operated submersible (ROV). The GPS positioning module 18 is used for positioning the remotely operated submersible (ROV) and setting the running track. After analyzing the waters to be measured, the operator designs the running route of the remotely operated submersible (ROV). Through the GPS positioning module to plan and preset waypoints, the remotely operated submersible (ROV) is automatically navigated to each waypoint, and the measurement of all waters is gradually completed.

[0043] The data transmission module 19 is used to control the engine 20, which can be connected to the handheld remote control terminal through a wireless signal. It is convenient for the operator to manually take over the remote control vehicle (ROV) when necessary. The engine 20 adopts a DC permanent magnet motor with a voltage of 12V, a power of 50W, and a maximum speed of 3000 rpm.

[0044] An operating method for measuring sludge bed distribution by combining sonar with a remotely operated submersible, the method comprising the following steps:

[0045] (1) Design waypoints according to the actual conditions of the waters to be measured: calculate the maximum interval L of the route, and reasonably preset waypoints through GPS positioning. Each waypoint sequentially constitutes the preset running trajectory of the ROV to ensure that the ROV can measure the bottom of all waters. The forward speed of the remotely operated vehicle (ROV) is controlled at 2-4 km / h to ensure the accuracy of sonar data;

[0046] (2) After the waypoint setting is completed, the ROV is started, guided by GPS to the initial waypoint and the sonar measurement is started. The 3D stereo imaging sonar can penetrate to the surface of the mud layer at the bottom of the water area and record the mud layer structure in the sonar's own storage system;

[0047] (3) The ROV passes through all preset waypoints in sequence, completes the record of the mud layer structure at the bottom of the water area, and finally returns;

[0048] (4) Using 3D stereo imaging sonar combined with GPS, we can obtain three sets of data (X i , Y i , Z i ), where X i , Y i Represents longitude and latitude respectively, Z i Represents the water depth from the water surface to the sludge layer at the location; the actual depth of the structure minus Z i You can get the longitude and latitude (X i , Y i ) point;

[0049] Application example: A surface flow artificial wetland in Zhejiang was selected to measure the bottom sludge bed structure. The wetland is 14.8m wide, 91.2m long, and has an average water depth of about 1.43m. The surface flow artificial wetland has been in operation for more than 400 days, and no dredging of the bottom sludge has been carried out during its operation. The current water body is black and smelly, indicating that there is a lot of sludge deposited at the bottom, which needs to be cleared and disposed of.

[0050] Since the water area to be measured is basically rectangular, zigzag navigation is adopted, the sonar frequency is 455KHz, and the beam angle α=50°. By calculation, the maximum allowable interval L of the route is 1.07m, and the actual operation interval is 1.0m. The preset waypoints are located by GPS, and each waypoint constitutes the preset operation track of the ROV in turn, so that the ROV can go back and forth in the wetland to ensure that the bottom of the entire water area can be measured. After the waypoint setting is completed, the ROV is started, guided by GPS to the initial waypoint and the sonar measurement is started. The 3D stereo imaging sonar can penetrate to the surface of the sludge layer at the bottom of the water area and record the sludge layer structure in the sonar's own storage system. During the measurement, the forward speed of the remotely operated vehicle (ROV) is controlled to 2 kilometers per hour to ensure the accuracy of the sonar data. The remotely operated vehicle (ROV) took 67 minutes to complete all measurements and collected 52,260 data.

[0051] By combining 3D stereo imaging sonar with GPS, three sets of data (X i , Y i , Z i ), where X i , Y i Represents longitude and latitude respectively, Z i Represents the water depth from the water surface to the sludge layer at the location. Subtract Z from the actual depth of the structure. i You can get the longitude and latitude (X i , Y i ) point. Based on the measured data, a 3D structure diagram of the bottom sludge bed of the surface flow constructed wetland was drawn ( Figure 3 ). The results show that the sludge bed thickness at the water inlet end of the artificial wetland is relatively small, with an average sludge bed thickness of 18.23cm. The reason may be that the water inlet scouring makes it difficult for the sludge to deposit. As the water flows into the wetland, the flow rate gradually decreases, forming a plug flow effect in the surface flow wetland. After that, the sludge gradually begins to deposit and forms a thick sludge bed near the wetland outlet. The maximum sludge bed thickness at the bottom can reach 40.21cm. The present invention effectively determines the sludge bed structure at the bottom of the surface flow artificial wetland. The implementation is simple, fast and time-saving. It has good economy and practicality, and provides technical support for subsequent dredging and wetland reconstruction.

Claims

1. A device for measuring sludge bed distribution by combining sonar with a remotely operated submersible, characterized in that: The device comprises a remote-controlled submersible body, a GPS positioning module, a sonar module and a data transmission module. The remote-controlled submersible body is equipped with a GPS positioning module and a sonar module, and the bottom sludge bed structure is measured and recorded by sonar. After the movement trajectory of the remote-controlled submersible is preset, the GPS positioning module is used to control the movement of the remote-controlled submersible to ensure that the sonar can measure the entire bottom range. The data transmission module is used to control the engine of the remote-controlled submersible, and the remote-controlled submersible is an ROV. The ROV route adopts a zigzag reciprocating navigation, and ensures that the sonar can fully cover the bottom of the water area, and the interval between two parallel adjacent routes should not be greater than the maximum route interval L; The maximum route interval L is calculated using the following formula: in: L: the maximum allowable interval between adjacent routes, in meters; H: water depth, in m; α: beam angle, when the sonar measurement frequency is 455KHz, α=50°; when the sonar measurement frequency is 800KHz, α=20°; k: safety factor, k=0.

8.

2. The device for measuring sludge bed distribution by combining sonar with remote-controlled submersible as claimed in claim 1, characterized in that: The main body of the submersible consists of a hull, an engine, a propeller, and a rechargeable lithium battery. The hull is 60-100cm long, 30-50cm wide, and has a maximum draft of 15-20cm. The hull is injection molded using an engineering plastic mold, and fixing clamps are pre-installed on the bow and both sides of the hull. The hull has a sealed top cover to prevent rain or water splashes from splashing into the cabin; the engine uses a DC permanent magnet motor with a voltage of 12v, a power of 30-50w, and a maximum speed of 3000-4000 rpm; a dual engine is used to control a dual propeller, the propeller is installed at the tail of the hull, the propeller is connected to the engine through a shaft, and the forward, backward, and steering of the hull are controlled by adjusting the speeds of the two sets of propellers respectively. The voltage of the rechargeable lithium battery is 12v, and the battery capacity is 30-50Ah. The rechargeable lithium battery is installed in the middle of the hull to power the equipment in the remote-controlled submersible.

3. The device for measuring sludge bed distribution by combining sonar with remote-controlled submersible according to claim 1 or 2, characterized in that: The GPS positioning module is used for positioning the remote-controlled submersible and setting its running track. By analyzing the waters to be measured, the running route of the remote-controlled submersible is designed in advance, and various waypoints are set according to the route. The remote-controlled submersible is navigated by the GPS positioning module to navigate to each waypoint in turn. Each waypoint constitutes the running route, so that the submersible can gradually complete the measurement of all waters.

4. The device for measuring sludge bed distribution by combining sonar with remote-controlled submersible according to claim 1 or 2, characterized in that: The sonar module includes a sonar host and a full-scan sonar probe. The sonar is powered by 12V. The sonar host must have a 3D stereo imaging function with a frequency of 455 / 800KHz and a minimum detection depth of no more than 1.0m. The full-scan sonar probe is installed at the bottom of the bow through a fixing fixture at the bow, away from the propeller to avoid interference.

5. The device for measuring sludge bed distribution by combining sonar with remote-controlled submersible according to claim 1 or 2, characterized in that: The data transmission module is connected to the handheld remote control terminal via a wireless signal.

6. The device for measuring sludge bed distribution by combining sonar with remote-controlled submersible according to claim 1 or 2, characterized in that: The device also includes a hull stabilizer, which is two identical engineering plastic injection-molded cone barrels connected to pre-installed fixing clamps on both sides of the submersible hull through aluminum alloy profiles to increase the stability of the hull in the water. The length of the cone barrel stabilizer is 40-60% of the total length of the hull, and the cone barrel diameter is 5-10 cm.

7. An operating method implemented by the device for measuring sludge bed distribution by combining sonar with a remotely operated submersible as claimed in claim 1, characterized in that: The method comprises the following steps: (1) Design waypoints according to the actual situation of the waters to be measured: calculate the maximum interval L of the route, and reasonably preset waypoints through GPS positioning. Each waypoint sequentially constitutes the preset running track of the ROV to ensure that the ROV can measure the bottom of all waters. The forward speed of the ROV is controlled at 2-4 km / h to ensure the accuracy of the sonar data; (2) After the waypoint setting is completed, the ROV is started, guided by GPS to the initial waypoint and the sonar measurement is started. The 3D stereo imaging sonar can penetrate to the surface of the mud layer at the bottom of the water area and record the mud layer structure in the sonar's own storage system; (3) The ROV passes through all preset waypoints in sequence, completes the record of the mud layer structure at the bottom of the water area, and finally returns; (4) Using 3D stereo imaging sonar combined with GPS, we can obtain three sets of data (X i , Y i , Z i ), where X i , Y i Represents longitude and latitude respectively, Z i Represents the water depth from the water surface to the sludge layer at the location; the actual depth of the structure minus Z i You can get the longitude and latitude (X i , Y i ) point sludge layer thickness; (5) After combining the data of each point, the 3D structure of the sludge bed at the bottom of the entire water area is obtained.

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