Ship engine tail gas washing wastewater treatment device and operation method thereof

Abstract

The invention provides a ship engine tail gas washing wastewater treatment device and an operation method thereof, belongs to the technical field of ship wastewater treatment, and solves the problem that the existing ship tail gas washing wastewater treatment technology has obvious limitation. The PH adjusting box, the first control valve, the electrostatic flocculation device, the second control valve and the centrifugal machine are sequentially connected, a waste liquid outlet of the centrifugal machine can be communicated with the first discharge pipeline or the membrane separator, an outlet of the membrane separator is communicated with the second discharge pipeline through the seventh control valve, and the input end of the sixth control valve is communicated with the outlet of the membrane separator. Two ends of the fifth control valve are respectively communicated with the output end of the sixth control valve and the inlet of the membrane separator, two ends of the third control valve are respectively communicated with the output end of the sixth control valve and the inlet of the centrifugal machine, and the wastewater monitoring device can monitor the quality of wastewater at the outlet of the centrifugal machine and the outlet of the membrane separator. The device can efficiently remove various pollutants in the washing wastewater.

Description

Technical Field

[0001] The present invention belongs to the technical field of ship wastewater treatment, and in particular relates to a ship engine exhaust gas washing wastewater treatment device and an operating method thereof. Background Art

[0002] In the shipping industry, ships, the primary mode of transport for global trade, produce large amounts of exhaust gases containing pollutants such as sulfur oxides, particulate matter, and heavy metals. To address increasingly stringent environmental regulations, marine engine exhaust treatment systems, particularly exhaust scrubbers, have become widely used.

[0003] Exhaust gas scrubbers effectively remove harmful substances from exhaust gases through a water scrubbing process, but they also produce large amounts of highly polluted wastewater. This wastewater contains not only heavy metals like lead, mercury, and copper, but also acidic substances like sulfuric acid. If discharged directly into the ocean without proper treatment, it can cause severe pollution to the marine environment, threatening marine life and disrupting ecological balance.

[0004] Existing ship exhaust gas washing wastewater treatment technology has significant limitations: traditional physical separation methods, such as simple sedimentation and filtration, are difficult to remove fine suspended matter and soluble pollutants in the wastewater, while chemical treatment methods require the consumption of large amounts of chemical agents, which not only increases treatment costs but may also cause secondary pollution. In addition, biological treatment methods are difficult to implement due to the complex and toxic composition of the wastewater. Summary of the Invention

[0005] In view of this, in order to solve the problem of significant limitations of existing ship exhaust scrubbing wastewater treatment technology, the present invention proposes a ship engine exhaust scrubbing wastewater treatment device and an operating method thereof.

[0006] To achieve the above object, the present invention adopts the following technical solutions: A ship engine exhaust gas washing wastewater treatment device is used to treat ship engine exhaust gas washing wastewater, including a pH adjustment module and a wastewater treatment module; The pH regulating module includes a lifting pump, a medicine box, a metering pump and a pH regulating box. The medicine box is connected to the pH regulating box through the metering pump, and the output end of the lifting pump is connected to the inlet of the pH regulating box. The wastewater treatment module includes a first control valve, an electrostatic flocculation device, a second control valve, a centrifuge, a wastewater monitoring device, a membrane separator, a third control valve, a fourth control valve, a fifth control valve, a sixth control valve and a seventh control valve. The outlet of the pH regulating box is connected to the inlet of the electrostatic flocculation device through the first control valve, and the outlet of the electrostatic flocculation device is connected to the inlet of the centrifuge through the second control valve. The fourth control valve has a first port, a second port and a third port. The first port can be connected to the second port or the third port. The waste liquid outlet of the centrifuge is connected to the first port of the fourth control valve, the second port of the fourth control valve is connected to the first discharge pipeline, the third port of the fourth control valve is connected to the inlet of the membrane separator, and the outlet of the membrane separator is connected to the second discharge pipeline through the seventh control valve. The input end of the sixth control valve is connected to the outlet of the membrane separator, the two ends of the fifth control valve are respectively connected to the output end of the sixth control valve and the inlet of the membrane separator, and the two ends of the third control valve are respectively connected to the output end of the sixth control valve and the inlet of the centrifuge. The wastewater monitoring device can monitor the water quality of the wastewater at the outlet of the centrifuge and the outlet of the membrane separator.

[0007] As an optimal method for the above-mentioned ship engine exhaust gas washing wastewater treatment device, the electrostatic flocculation device includes an electrochemical power supply and an electrostatic flocculation box. The electrostatic flocculation box is provided with a waste liquid inlet, an electrostatic flocculation channel and a waste liquid outlet which are connected in sequence. A plurality of iron electrodes are provided in the electrostatic flocculation channel, and the plurality of iron electrodes are all connected to the electrochemical power supply wires. As an optimal method for the above-mentioned ship engine exhaust gas washing wastewater treatment device, the electrostatic flocculation channel includes a plurality of electrostatic flocculation tubes spaced apart and parallel to each other in the vertical direction and a plurality of short vertical pipes parallel to each other. The plurality of electrostatic flocculation tubes are connected by short vertical pipes staggered between adjacent electrostatic flocculation tubes to form a single passage.

[0008] As a preferred method of the above-mentioned ship engine exhaust gas washing wastewater treatment device, the waste liquid outlet of the electrostatic flocculation box is provided with a one-way valve, and the wastewater flows into the centrifuge through the one-way valve.

[0009] As a preferred method of the above-mentioned ship engine exhaust gas washing wastewater treatment device, the wastewater treatment module also includes a waste residue collection box, and the waste residue collection box is connected to the waste residue outlet of the centrifuge.

[0010] As an optimal method for the above-mentioned ship engine exhaust gas washing wastewater treatment device, the membrane separator is provided with multiple parallel tubular membranes, and multiple filter holes are provided on the cylindrical surface of the tubular membranes. The apertures of the filter holes of the multiple tubular membranes decrease from the outside to the inside.

[0011] As an optimal method of the above-mentioned ship engine exhaust gas washing wastewater treatment device, the wastewater treatment module also includes a controller, which can receive real-time data from the wastewater monitoring device and control the switching behavior of the third control valve, the fourth control valve, the fifth control valve, the sixth control valve and the seventh control valve.

[0012] As a preferred method of the above-mentioned ship engine exhaust gas washing wastewater treatment device, the pH adjustment module also includes a pH sensor, and the pH sensor is arranged in the pH adjustment box.

[0013] The present invention also provides an operating method of a ship engine exhaust gas washing wastewater treatment device, which uses the above-mentioned ship engine exhaust gas washing wastewater treatment device, comprising: S1: The wastewater enters the pH regulating tank under the traction of the lifting pump. The reagent tank pumps alkali solution into the pH regulating tank through the metering pump to adjust the pH value of the wastewater in the pH regulating tank; S2: The alkaline wastewater after pH adjustment enters the electrostatic flocculation device, which can condense the impurities in the wastewater into agglomerates; S3: After flocculation, the wastewater enters the centrifuge. Under the high-speed centrifugal action of the centrifuge, the impurity flocculants in the wastewater are separated from the wastewater; S4: The wastewater monitoring device detects the wastewater flowing out of the centrifuge; If the quality of the wastewater meets the standard, the first port of the fourth control valve is connected to the second port, and the wastewater flowing out of the centrifuge is directly discharged from the first discharge management; If the wastewater quality does not meet the standards, the first port of the fourth control valve is connected to the third port, and the wastewater flowing out of the centrifuge enters the membrane separator, where the wastewater is further filtered under the action of the multi-stage membrane of the membrane separator; S5: The wastewater monitoring device detects the wastewater discharged from the membrane separator; If the pH, PAHS, turbidity and sulfite (nitrate) content in the wastewater reaches the IMO discharge standard, the seventh control valve opens and the wastewater is discharged directly from the second discharge pipeline; If one or two of the pH, PAHS, turbidity and sulfite (nitrate) content in the wastewater fail to meet the IMO emission standards, the fifth and sixth control valves will be opened to execute a small waste liquid circulation; If more than three of the pH, PAHS, turbidity, and sulfite (nitrate) contents in the wastewater fail to meet the IMO emission standards, the sixth control valve and the third control valve are opened to execute the waste liquid large circulation.

[0014] As a preferred embodiment of the method for operating the above-mentioned ship engine exhaust gas washing wastewater treatment device, in S1, the pH value of the wastewater in the pH regulating tank is adjusted until the pH value of the wastewater reaches 8 or 9.

[0015] Compared with the prior art, the beneficial effects of the ship engine exhaust gas washing wastewater treatment device and the operation method thereof provided by the present invention are: (1) The present invention provides a ship engine exhaust gas washing wastewater treatment device and an operating method thereof. The ship engine exhaust gas washing wastewater treatment device efficiently removes various pollutants in the washing wastewater by integrating three core technologies: electrostatic flocculation + centrifugal separation + membrane filtration.

[0016] (2) The present invention provides a ship engine exhaust gas washing wastewater treatment device and its operation method. In the pH adjustment module, by adding alkaline solution to the wastewater, the pH value of the wastewater is adjusted, thereby achieving the pH value of the sea discharge wastewater in compliance with regulations. At the same time, the efficiency of each treatment unit is optimized, so that the overall process has both high efficiency and stability.

[0017] (3) The present invention provides a ship engine exhaust gas washing wastewater treatment device and an operating method thereof. The ship engine exhaust gas washing wastewater treatment device reduces the volume of the entire device and improves the space utilization rate of the ship by integrating multiple devices into the same device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings: Figure 1 1. It is a structural schematic diagram of a ship engine exhaust gas washing wastewater treatment device provided by a specific embodiment of the present invention; Figure 2 It is a structural schematic diagram of an electrostatic flocculation box of a ship engine exhaust gas washing wastewater treatment device provided by a specific embodiment of the present invention.

[0019] In the picture: 1. Lifting pump; 2. Reagent box; 3. Metering pump; 4. pH regulating box; 5. First control valve; 6. Electrostatic flocculation device; 7. Second control valve; 8. Centrifuge; 9. Wastewater monitoring device; 10. Membrane separator; 11. Third control valve; 12. Fourth control valve; 13. Fifth control valve; 14. Sixth control valve; 15. Seventh control valve; 16. First discharge pipeline; 17. Second discharge pipeline; 18. Controller; 19. Waste residue collection box; 61. Electrochemical power source; 62. Waste liquid inlet; 63. Electrostatic flocculation channel; 64. Waste liquid outlet; 65. Iron electrode. DETAILED DESCRIPTION The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features therein can be combined with each other in the absence of conflict, and the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0020] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0021] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0022] In the description of this embodiment, terms such as "upper," "lower," and "right" are used to refer to positions or locations based on the positions or locations shown in the accompanying drawings. These terms are intended solely to facilitate description and simplify operation, and are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meaning.

[0023] See also Figure 1-2Description of this embodiment. The present invention provides a ship engine exhaust gas washing wastewater treatment device and an operation method thereof. The ship engine exhaust gas washing wastewater treatment device is used to treat ship engine exhaust gas washing wastewater. The ship engine exhaust gas washing wastewater treatment device includes a pH adjustment module and a wastewater treatment module; the pH adjustment module includes a lifting pump 1, a reagent box 2, a metering pump 3 and a pH adjustment box 4, the reagent box 2 is connected to the pH adjustment box 4 through the metering pump 3, and the output end of the lifting pump 1 is connected to the inlet of the pH adjustment box 4; the wastewater treatment module includes a first control valve 5, an electrostatic flocculation device 6, a second control valve 7, a centrifuge 8, a wastewater monitoring device 9, a membrane separator 10, a third control valve 11, a fourth control valve 12, a fifth control valve 13, a sixth control valve 14 and a seventh control valve 15, the outlet of the pH adjustment box 4 is connected to the inlet of the electrostatic flocculation device 6 through the first control valve 5, and the electrostatic flocculation device 6 is connected to the inlet of the electrostatic flocculation device 6. The outlet of the flocculation device 6 is connected to the inlet of the centrifuge 8 through the second control valve 7. The fourth control valve 12 has a first port, a second port and a third port. The first port can be connected to the second port or the third port. The waste liquid outlet 64 of the centrifuge 8 is connected to the first port of the fourth control valve 12. The second port of the fourth control valve 12 is connected to the first discharge pipeline 16. The third port of the fourth control valve 12 is connected to the inlet of the membrane separator 10. The outlet of the membrane separator 10 is connected to the second discharge pipeline 17 through the seventh control valve 15. The input end of the sixth control valve 14 is connected to the outlet of the membrane separator 10. The two ends of the fifth control valve 13 are respectively connected to the output end of the sixth control valve 14 and the inlet of the membrane separator 10. The two ends of the third control valve 11 are respectively connected to the output end of the sixth control valve 14 and the inlet of the centrifuge 8. The wastewater monitoring device 9 can monitor the water quality of the wastewater at the outlet of the centrifuge 8 and the outlet of the membrane separator 10.

[0024] This marine engine exhaust scrubber wastewater treatment unit integrates three core technologies: electrostatic flocculation, centrifugal separation, and membrane filtration. It efficiently removes various pollutants from wastewater. A pH adjustment module dynamically controls wastewater pH, optimizing the performance of each treatment unit and ensuring both high efficiency and stability throughout the process. This marine engine exhaust scrubber wastewater treatment unit provides a more environmentally friendly solution for marine exhaust scrubber wastewater treatment, filling a technological gap and delivering significant economic and environmental benefits.

[0025] Optionally, the electrostatic flocculation device 6 includes an electrochemical power source 61 and an electrostatic flocculation box. The electrostatic flocculation box has a waste liquid inlet 62, an electrostatic flocculation channel 63, and a waste liquid outlet 64, which are sequentially connected. The electrostatic flocculation channel 63 is provided with multiple iron electrodes, each of which is connected to the electrochemical power source 61 by wires. Under the power of the electrochemical power source 61, the iron ions in the iron electrodes and the hydroxide ions in the wastewater form highly active flocculation groups, which adsorb suspended impurities in the wastewater and condense into impurity flocs.

[0026] Optionally, the electrostatic flocculation channel 63 includes a plurality of electrostatic flocculation tubes spaced apart and parallel to each other in the vertical direction and a plurality of short vertical tubes parallel to each other. The plurality of electrostatic flocculation tubes are connected by short vertical tubes staggered between adjacent electrostatic flocculation tubes to form a single passage. Iron electrodes are provided at both ends of each electrostatic flocculation tube. In this embodiment, there are five electrostatic flocculation tubes. Counting from top to bottom, the first and second electrostatic flocculation tubes are connected through a short vertical tube arranged on the right, the second and third electrostatic flocculation tubes are connected through a short vertical tube arranged on the left, the third and fourth electrostatic flocculation tubes are connected through a short vertical tube arranged on the right, and the fourth and fifth electrostatic flocculation tubes are connected through a short vertical tube arranged on the left. The waste liquid inlet 62 is connected to the left end of the first electrostatic flocculation tube, and the waste liquid outlet 64 is connected to the right side of the fifth electrostatic flocculation tube.

[0027] Optionally, the waste liquid outlet 64 of the electrostatic flocculation box is provided with a one-way valve, through which waste water flows into the centrifuge 8. The one-way valve can prevent waste water in the centrifuge 8 from flowing into the electrostatic flocculation box.

[0028] Optionally, the wastewater treatment module further comprises a waste residue collection box 19 , which is in communication with the waste residue outlet of the centrifuge 8 . The waste residue collection box 19 is used to collect impurities separated by the centrifuge 8 .

[0029] Optionally, the membrane separator 10 is provided with a plurality of parallel tubular membranes, each having a plurality of filtration holes formed on its cylindrical surface. The pore sizes of the filtration holes of the plurality of tubular membranes decrease from the outside to the inside. When wastewater enters the tubular membranes, pollutants in the wastewater that are smaller than the pore size of the filtration holes pass through the tubular membranes along with the wastewater, while pollutants that are larger than the pore size of the filtration holes remain within the tubular membranes. Within the membrane separator 10, the pore sizes of the filtration holes of the plurality of tubular membranes decrease from the outside to the inside, thereby forming a multi-stage filtration process.

[0030] Optionally, the wastewater treatment module further includes a controller 18, which can receive real-time data from the wastewater monitoring device 9 and control the switching behavior of the third control valve 11, the fourth control valve 12, the fifth control valve 13, the sixth control valve 14 and the seventh control valve 15.

[0031] Optionally, the pH adjustment module further includes a pH sensor, which is disposed in the pH adjustment box 4. The pH sensor is used to detect the pH value of the wastewater in the pH adjustment box 4.

[0032] The present invention also provides an operating method of a ship engine exhaust gas washing wastewater treatment device, which uses the above-mentioned ship engine exhaust gas washing wastewater treatment device, comprising: S1: The wastewater enters the pH regulating tank 4 under the traction of the lifting pump 1, and the reagent tank 2 pumps alkali solution into the pH regulating tank 4 through the metering pump 3 to adjust the pH value of the wastewater in the pH regulating tank 4 until the pH value of the wastewater reaches 8 or 9.

[0033] S2: The alkaline wastewater after pH adjustment enters the electrostatic flocculation device 6, which can condense the impurities in the wastewater into agglomerates.

[0034] S3: After the flocculation, the wastewater enters the centrifuge 8. Under the high-speed centrifugal action of the centrifuge 8, the impurity flocculants in the wastewater are separated from the wastewater.

[0035] S4: The wastewater monitoring device 9 detects the wastewater flowing out of the centrifuge 8.

[0036] If the quality of the wastewater meets the standard, the first port and the second port of the fourth control valve 12 are connected, and the wastewater flowing out of the centrifuge 8 is directly discharged from the first discharge management.

[0037] If the quality of the wastewater does not meet the standards, the first port of the fourth control valve 12 is connected to the third port, and the wastewater flowing out of the centrifuge 8 enters the membrane separator 10, where the wastewater is further filtered under the action of the multi-stage membrane of the membrane separator 10.

[0038] S5: The wastewater monitoring device 9 detects the wastewater discharged from the membrane separator 10.

[0039] If the pH, PAHS, turbidity and sulfite (nitrate) content in the wastewater reach the IMO emission standards, the seventh control valve 15 is opened and the wastewater is directly discharged from the second discharge pipeline 17.

[0040] If one or two of the pH, PAHS, turbidity and sulfite (nitrate) content in the wastewater do not meet the IMO emission standards, the fifth control valve 13 and the sixth control valve 14 are opened to perform a small waste liquid circulation.

[0041] If more than three of the pH, PAHS, turbidity, and sulfite (nitrate) content in the wastewater fail to meet the IMO emission standards, the sixth control valve 14 and the third control valve 11 are opened to execute a large waste liquid circulation.

[0042] During operation, the marine engine exhaust scrubber wastewater treatment system draws the engine washwater from the vessel into the pH adjustment tank 4, driven by lift pump 1. Metering pump 3 then pumps NaOH solution from reagent tank 2 into the pH adjustment tank 4 to adjust the wastewater's pH to 8 or 9, meeting discharge and flocculation requirements. The pH-adjusted alkaline wastewater then enters the electrostatic flocculation tank. Powered by an electrochemical power source 61, the iron ions in the electrodes and the hydroxide ions in the water form highly active flocculation groups, which absorb suspended impurities in the wastewater and form flocculent clusters. Afterwards, the wastewater mixed with impurity flocs enters the centrifuge 8. Under the action of high-speed centrifugation, the large impurity flocs in the waste liquid are separated from the wastewater and sent to the waste residue collection box 19. After the separated wastewater flows out of the centrifuge 8, it is tested by the wastewater monitoring device 9. If the wastewater quality meets the standards, that is, if the pH, PAHS, turbidity and sulfite (nitrate) content in the wastewater meet the IMO emission standards, the controller 18 controls the first port of the fourth control valve 12 to connect with the second port, so that the outlet of the centrifuge 8 is connected with the first discharge pipeline 16, so that the wastewater is directly discharged without passing through the subsequent membrane separator 10. On the contrary, if the wastewater quality does not meet the standards, the controller 18 controls the first port of the fourth control valve 12 to connect with the third port, so that the outlet of the centrifuge 8 is connected with the membrane separator 10, and the wastewater enters the membrane separator 10. Wastewater that does not meet the standards enters the membrane separator 10, where it is further filtered by the multi-stage membranes. The discharged wastewater is then tested again by the wastewater monitoring device 9. If the wastewater meets the standards, it is directly discharged from the second discharge pipeline 17. If the wastewater does not meet the standards slightly, that is, if one or two of the pH, PAHS, turbidity, and sulfite (nitrate) content in the wastewater do not meet the IMO emission standards, the fifth control valve 13 and the sixth control valve 14 are opened, the seventh control valve 15 and the third control valve 11 remain closed, and the wastewater is returned to the inlet of the membrane filter, performing a small waste liquid circulation until the wastewater meets the standards. If the wastewater does not meet the standards seriously, that is, if more than three of the pH, PAHS, turbidity, and sulfite (nitrate) content in the wastewater do not meet the IMO emission standards, the sixth control valve 14 and the third control valve 11 are opened, the seventh control valve 15 and the fifth control valve 13 remain closed, and the wastewater is returned to the inlet of the centrifuge 8, performing a large waste liquid circulation until the wastewater meets the standards.

[0043] Obviously, the embodiments of the present invention disclosed above are intended only to help illustrate the present invention. The embodiments do not describe all details in detail, nor do they limit the invention to the specific embodiments described. Numerous modifications and variations are possible based on the contents of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. It is not necessary and impossible to list all embodiments here.

Claims

1. A ship engine exhaust gas washing wastewater treatment device for treating ship engine exhaust gas washing wastewater, characterized in that: Including pH adjustment module and wastewater treatment module; The pH regulating module comprises a lifting pump (1), a medicine box (2), a metering pump (3) and a pH regulating box (4); the medicine box (2) is connected to the pH regulating box (4) via the metering pump (3); and the output end of the lifting pump (1) is connected to the inlet end of the pH regulating box (4); The wastewater treatment module comprises a first control valve (5), an electrostatic flocculation device (6), a second control valve (7), a centrifuge (8), a wastewater monitoring device (9), a membrane separator (10), a third control valve (11), a fourth control valve (12), a fifth control valve (13), a sixth control valve (14) and a seventh control valve (15); the outlet of the pH regulating box (4) is connected to the inlet of the electrostatic flocculation device (6) through the first control valve (5); the outlet of the electrostatic flocculation device (6) is connected to the inlet of the centrifuge (8) through the second control valve (7); the fourth control valve (12) has a first port, a second port and a third port; the first port can be communicated with the second port or the third port; the waste liquid outlet (64) of the centrifuge (8) is connected to the fourth control valve (12) The first port of the fourth control valve (12) is connected to the first discharge pipeline (16), the second port of the fourth control valve (12) is connected to the first discharge pipeline (16), the third port of the fourth control valve (12) is connected to the inlet of the membrane separator (10), the outlet of the membrane separator (10) is connected to the second discharge pipeline (17) through the seventh control valve (15), the input end of the sixth control valve (14) is connected to the outlet of the membrane separator (10), the two ends of the fifth control valve (13) are respectively connected to the output end of the sixth control valve (14) and the inlet of the membrane separator (10), the two ends of the third control valve (11) are respectively connected to the output end of the sixth control valve (14) and the inlet of the centrifuge (8), and the wastewater monitoring device (9) can monitor the water quality of the wastewater at the outlet of the centrifuge (8) and the outlet of the membrane separator (10).

2. The marine engine exhaust gas washing wastewater treatment device according to claim 1, characterized in that: The electrostatic flocculation device (6) comprises an electrochemical power source (61) and an electrostatic flocculation box. The electrostatic flocculation box is provided with a waste liquid inlet (62), an electrostatic flocculation channel (63) and a waste liquid outlet (64) which are connected in sequence. A plurality of iron electrodes are provided in the electrostatic flocculation channel (63), and the plurality of iron electrodes are all connected to the electrochemical power source (61) wires.

3. The ship engine exhaust gas washing wastewater treatment device according to claim 2, characterized in that: The electrostatic flocculation channel (63) comprises a plurality of electrostatic flocculation tubes spaced apart and parallel to each other in the vertical direction and a plurality of short vertical tubes parallel to each other. The plurality of electrostatic flocculation tubes are connected by the short vertical tubes staggered between adjacent electrostatic flocculation tubes to form a single channel.

4. The ship engine exhaust gas washing wastewater treatment device according to claim 2, characterized in that: The waste liquid outlet (64) of the electrostatic flocculation box is provided with a one-way valve, and the waste water flows into the centrifuge (8) through the one-way valve.

5. The ship engine exhaust gas washing wastewater treatment device according to claim 1, characterized in that: The wastewater treatment module further comprises a waste residue collection box (19), which is connected to the waste residue outlet of the centrifuge (8).

6. The ship engine exhaust gas washing wastewater treatment device according to claim 1, characterized in that: The membrane separator (10) is provided with a plurality of tubular membranes parallel to each other, and a plurality of filtering holes are provided on the cylindrical surface of the tubular membranes. The apertures of the filtering holes of the plurality of tubular membranes decrease sequentially from the outside to the inside.

7. The ship engine exhaust gas washing wastewater treatment device according to claim 1, characterized in that: The wastewater treatment module further comprises a controller (18), which is capable of receiving real-time data from the wastewater monitoring device (9) and controlling the switching behavior of the third control valve (11), the fourth control valve (12), the fifth control valve (13), the sixth control valve (14) and the seventh control valve (15).

8. The ship engine exhaust gas washing wastewater treatment device according to claim 1, characterized in that: The pH regulating module further comprises a pH sensor, which is arranged in the pH regulating box (4).

9. A method for operating a ship engine exhaust gas washing wastewater treatment device, characterized in that: The ship engine exhaust gas washing wastewater treatment device according to any one of claims 1 to 8 comprises: S1: The wastewater enters the pH regulating tank (4) under the traction of the lifting pump (1), and the reagent tank (2) pumps alkali solution into the pH regulating tank (4) through the metering pump (3) to adjust the pH value of the wastewater in the pH regulating tank (4); S2: The alkaline wastewater after pH adjustment enters the electrostatic flocculation device (6), which can condense the impurities in the wastewater into agglomerates; S3: After flocculation, the wastewater enters the centrifuge (8). Under the high-speed centrifugal action of the centrifuge (8), the impurity flocculants in the wastewater are separated from the wastewater; S4: The wastewater monitoring device (9) detects the wastewater flowing out of the centrifuge (8); If the quality of the wastewater meets the standard, the first port of the fourth control valve (12) is connected to the second port, and the wastewater flowing out of the centrifuge (8) is directly discharged from the first discharge management; If the quality of the wastewater does not meet the standard, the first port of the fourth control valve (12) is connected to the third port, and the wastewater flowing out of the centrifuge (8) enters the membrane separator (10), and the wastewater is further filtered under the action of the multi-stage membrane of the membrane separator (10); S5: The wastewater monitoring device (9) detects the wastewater discharged from the membrane separator (10); If the pH, PAHS, turbidity and sulfite (nitrate) content in the wastewater reach the IMO discharge standard, the seventh control valve (15) is opened and the wastewater is directly discharged from the second discharge pipeline (17); If one or two of the pH, PAHS, turbidity and sulfite (nitrate) content in the wastewater do not meet the IMO emission standards, the fifth control valve (13) and the sixth control valve (14) are opened to perform a small waste liquid circulation; If more than three of the pH, PAHS, turbidity, and sulfite (nitrate) content in the wastewater fail to meet the IMO emission standards, the sixth control valve (14) and the third control valve (11) are opened to execute the waste liquid large circulation.

10. The operating method of the ship engine exhaust gas washing wastewater treatment device according to claim 9, characterized in that: In S1, the pH value of the wastewater in the pH regulating tank (4) is adjusted until the pH value of the wastewater reaches 8 or 9.

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