A device and method for simulating freeze-thaw-electro-osmosis dewatering and decontamination of silt

Abstract

The present application belongs to the technical field of contaminated sludge treatment, and particularly relates to a sludge dewatering and decontamination test device and method simulating freeze-thaw-electroosmosis, which comprises: a model box module, the model box module being used for containing a sludge sample; an electroosmosis module, the electroosmosis module being arranged in the model box module and being used for applying an electric field to the sludge sample and discharging water and heavy metal pollutants in the model box module in an electroosmosis stage; a freeze-thaw module, the model box module and the electroosmosis module being placed in the freeze-thaw module, the freeze-thaw module being used for discharging water and heavy metal pollutants in the sludge in a freeze-thaw stage and adjusting the environmental temperature in the model box module in the electroosmosis stage; and an acquisition module, the acquisition module being used for acquiring temperature data in the model box module, electric field data applied by the electroosmosis module, water sample data of the water and heavy metal pollutants, and crack change information of the sludge sample. A sludge dewatering and decontamination simulation test method using the above device is also provided. The device can significantly improve the test efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of contaminated sludge treatment, and particularly relates to a sludge dewatering and decontamination test device and method simulating freeze-thaw-electro-osmosis. BACKGROUND

[0002] In recent years, in order to change the water quality of lakes, ensure the normal flood discharge capacity of river channels, and improve the navigation capacity of ports and waterways, China has begun to plan large-scale dredging and desilting of some lakes, river channels, ports and waterways. The disposal method of on-site stacking is usually adopted, which will cause the following environmental problems: first, the sludge has the characteristics of high clay content and high water content, and simple stacking will cause waste of land resources; second, the sludge often contains a large amount of heavy metal pollutants, which is easy to cause secondary pollution to the surrounding soil and groundwater if not treated. Therefore, it is particularly crucial to implement dewatering and volume reduction and synchronous decontamination treatment of sludge.

[0003] Electro-osmosis is an electrochemical method that uses electric field as driving force to induce directional migration of water molecules and heavy metal ions, and has a fast dewatering speed and is suitable for low permeability soil, which has gradually shown great potential in sludge dewatering and synchronous decontamination. However, this technology also has obvious defects: soil cracking is serious in the later stage of electro-osmosis, resulting in low efficiency and high energy consumption, which to some extent limits the application of this technology in practice.

[0004] Freeze-thaw method as an environmentally friendly technology has received extensive attention in recent years. This technology has the advantages of economy and simultaneous dewatering and decontamination, but when the water content of sludge is low, the effect is often not good, and it is difficult to achieve deep dewatering and decontamination of sludge by simply using freeze-thaw method.

[0005] Combining freeze-thaw with electro-osmosis may be a more effective method for sludge dewatering and decontamination. Some scholars have done some exploratory work through some simple test devices, such as repeatedly pre-freezing and thawing the sludge in a refrigerator to enhance the mobility of heavy metal ions in the sludge, then stirring the frozen and thawed sludge evenly, and finally placing the sludge in a simple electro-osmosis test device for electro-osmosis decontamination, which effectively improves the decontamination efficiency of the sludge, but still has the following shortcomings:

[0006] ①The main goal is to remove heavy metal pollutants in sludge, and it cannot realize the integration of sludge dewatering and decontamination.

[0007] ②Freeze-thaw and electro-osmosis are carried out in two sets of test devices, which has low efficiency and cannot simulate the freeze-thaw process under complex temperature boundary.

[0008] ③During the test process, real-time monitoring of test data cannot be carried out.

[0009] ④The freezing temperature and electro-osmosis intervention time are set by human beings, which cannot maximize the efficiency of sludge dewatering and decontamination.

[0010] ⑤ During electroosmosis, fine particles migrate, and in the later stages, they are prone to clogging near the cathode electrode plate, resulting in low efficiency in drainage and decontamination.

[0011] Therefore, developing an intelligent and integrated experimental device and method for sludge dewatering and pollution removal that is highly efficient, economical, and can simulate the freeze-thaw electroosmotic coupling effect has significant engineering value and practical significance. Summary of the Invention

[0012] The purpose of this invention is to provide a test apparatus and method for simulating freeze-thaw-electroosmosis sludge dewatering and decontamination, so as to solve the above-mentioned problems.

[0013] To achieve the above objectives, the present invention provides the following solution:

[0014] A simulated freeze-thaw-electroosmosis sludge dewatering and decontamination test device includes:

[0015] A model box module, which is used to hold sludge samples;

[0016] An electroosmosis module is installed inside the model box module. The electroosmosis module is used to apply an electric field to the sludge sample and to remove water and heavy metal pollutants from the model box module during the electroosmosis stage.

[0017] The freeze-thaw module, the model box module and the electroosmosis module are both placed inside the freeze-thaw module. The freeze-thaw module is used to remove moisture from the sludge and remove heavy metal pollutants during the freeze-thaw stage, and to regulate the ambient temperature inside the model box module during the electroosmosis stage.

[0018] The acquisition module is used to acquire temperature data inside the model box module, electric field data applied by the electroosmosis module, water sample data of moisture and heavy metal pollutants, and crack change information of the sludge sample.

[0019] Optionally, the model box module includes:

[0020] Box;

[0021] A sludge sample box is fixedly connected inside the box. The sludge sample box is used to hold sludge samples and is provided with a viewing window for observation.

[0022] The water collection area is formed by one side of the sludge sample box and the inner wall of the box. The water collection area is connected to the sludge sample box. The electroosmosis module is installed inside the sludge sample box. The water collection area is used to temporarily store water and heavy metal pollutants discharged from the sludge. A drainage hole is opened on one side of the bottom of the water collection area.

[0023] A reverse filtration module is in communication with the water outlet end of the sludge sample box, and a water outlet end of the reverse filtration module is in communication with the water collecting area, and the reverse filtration module prevents the water outlet end of the sludge sample box from being blocked.

[0024] Optionally, the sludge sample box is made of double-layer hollow transparent organic glass around and at the bottom, and the sludge sample box is located on the front panel and is engraved with grid lines.

[0025] Optionally, the electro-osmosis module comprises:

[0026] A first frozen electrode plate and a second frozen electrode plate are installed in the sludge sample box, the first frozen electrode plate is located near the water collecting area, and the first frozen electrode plate is provided with a fluid flow channel; the first frozen electrode plate and the second frozen electrode plate are electrically connected with the acquisition module, and the acquisition module is used for providing electric energy.

[0027] Optionally, the first frozen electrode plate comprises:

[0028] An outer heat insulation plate one is provided with a channel for fluid passing through;

[0029] An inner metal plate one is fixedly connected with the outer heat insulation plate one, and the structure of the inner metal plate one matches that of the outer heat insulation plate one; the inner metal plate one is used for contacting with the sludge sample;

[0030] A frozen liquid flow channel one is fixedly connected between the outer heat insulation plate one and the inner metal plate one, and frozen liquid enters the frozen liquid flow channel one through a frozen liquid inlet one and is discharged from the frozen liquid flow channel one through a frozen liquid outlet one;

[0031] A semicircular cylindrical sealing protrusion and a groove one are arranged between the outer heat insulation plate one and the inner metal plate one, and are used for sealing the gap edge between the outer heat insulation plate one and the inner metal plate one after the outer heat insulation plate one and the inner metal plate one are spliced.

[0032] Optionally, the second frozen electrode plate comprises:

[0033] An outer heat insulation plate two;

[0034] An inner metal plate two is fixedly connected with the outer heat insulation plate two, and the outer heat insulation plate two and the inner metal plate two match in structure; the inner metal plate two is used for contacting with the sludge sample, and an anti-electric corrosion coating is applied to the surface of the inner metal plate two;

[0035] A frozen liquid flow channel two is fixedly connected between the outer heat insulation plate two and the inner metal plate two, and frozen liquid enters the frozen liquid flow channel two through a frozen liquid inlet two and is discharged from the frozen liquid flow channel two through a frozen liquid outlet two;

[0036] A semi-cylindrical sealing protrusion and groove are arranged between the outer layer of heat insulation board and the inner layer of metal plate, for sealing the gap between the outer layer of heat insulation board and the inner layer of metal plate after they are spliced.

[0037] Optionally, the reverse filtration module comprises:

[0038] A high-strength nylon plate outer frame is filled with a sand cushion layer, and the particle size of the sand cushion layer increases in the fluid flow direction;

[0039] A plurality of PVC drainage flower pipes are buried in the sand cushion layer, and the plurality of PVC drainage flower pipes are arranged in a matrix;

[0040] A large-aperture geotextile is fixed to the side of the high-strength nylon plate outer frame close to the silt sample box;

[0041] A small-aperture geotextile is fixed to the side of the high-strength nylon plate outer frame close to the catchment area.

[0042] Optionally, the freeze-thaw module comprises:

[0043] A constant temperature room;

[0044] A movable platform is slidably arranged at the inside bottom of the constant temperature room through horizontal telescopic guide rails, the model box module is placed in the movable platform, and the top end of the horizontal telescopic guide rail located at one end outside the constant temperature room is detachably connected with a vertical support through a movable bolt, and the vertical support is arranged vertically with the horizontal telescopic guide rail;

[0045] An LED cold light lamp is fixed to the inside top of the constant temperature room;

[0046] A temperature control cold bath box one is located outside the constant temperature room, and the inlet end and the outlet end of the temperature control cold bath box one are respectively connected with the refrigerant outlet one and the refrigerant inlet one through refrigerant inlet and outlet corrugated pipes one;

[0047] A temperature control cold bath box two is located outside the constant temperature room, and the inlet end and the outlet end of the temperature control cold bath box two are respectively connected with the refrigerant outlet two and the refrigerant inlet two through refrigerant inlet and outlet corrugated pipes two.

[0048] A silt dewatering and decontamination test method for simulating freeze-thaw-electro-osmosis, using the above-mentioned silt dewatering and decontamination test device for simulating freeze-thaw-electro-osmosis, comprises the following steps:

[0049] Fill the silt sample containing the pollution source into the model box module;

[0050] The control of the freeze-thaw module adjusts the temperature boundary of the silt sample at both ends in the model box module and the ambient temperature, carries out the silt dewatering and decontamination test of different freezing temperature gradients and different freeze-thaw cycle numbers, and determines the optimal freezing temperature gradient and freeze-thaw cycle number by using a multi-objective algorithm.

[0051] After the freeze-thaw cycle test under the optimal freeze-thaw condition determined above, the electro-osmosis module is controlled to carry out the electro-osmosis test to continue to discharge water and heavy metal pollutants.

[0052] The water sample data of water and heavy metal pollutants in the freeze-thaw stage and the electro-osmosis stage are obtained by the acquisition module, and the dewatering efficiency of the silt and the removal efficiency of the heavy metal ions are counted.

[0053] Optionally, the step of determining the optimal freezing temperature gradient and freeze-thaw cycle number by the multi-objective algorithm comprises:

[0054] According to the image data captured by the front high-definition digital camera in the acquisition module, the image processing technology is used to analyze the settlement amount change of the intersection points of the n grid lines in the front part of the silt sample after N freeze-thaw cycles under different freezing temperature gradients, and a first target optimization function is constructed with the settlement amount as the independent variable;

[0055] The surface image of the silt sample after N freeze-thaws under different freezing temperature gradients is processed by the top high-definition digital camera in the acquisition module, the area of the crack is calculated by counting the number of pixel points, and a second target optimization function is constructed with the crack area as the independent variable;

[0056] The first target function and the second target function are combined to establish a unified multi-objective optimization function, and the optimal freezing temperature gradient and freeze-thaw cycle number can be obtained when the function reaches a minimum value. Compared with the prior art, the present application has the following advantages and technical effects:

[0057] In use, the silt sample is placed in the model box module, and the model box module is placed in the freeze-thaw module, the freeze-thaw cycle of the silt sample placed in the model box module is carried out by the freeze-thaw module, and the electro-osmosis effect of the silt sample is generated by the electro-osmosis module, the freeze-thaw and electro-osmosis combined silt dewatering and decontamination test can be realized by setting the freeze-thaw condition and the electro-osmosis condition, the optimal freeze-thaw condition can be found, and compared with the traditional technology, the present application can realize the removal of pollutants and water in the silt in an integrated manner, the electro-osmosis module and the freeze-thaw module are integrated in a set of device to avoid sample transfer, and the test efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0058] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description only show some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without any creative effort:

[0059] Figure 1 Structure diagram of the present application;

[0060] Figure 2 Structure diagram of the present application;

[0061] Figure 3 Structure diagram of the present application;

[0062] Figure 4 Structure diagram of the present application;

[0063] Figure 5 Structure diagram of the present application;

[0064] Figure 6 Structure diagram of the present application;

[0065] Figure 7 Processing process diagram of the surface crack image of the silt sample obtained by the silt dewatering and decontamination test device simulating freeze-thaw-electro-osmosis;

[0066] Figure 8 Processing process diagram of the side surface image of the silt sample obtained by the silt dewatering and decontamination test device simulating freeze-thaw-electro-osmosis;

[0067] Wherein, 11, silt sample box; 111, grid lines; 12, catchment area; 121, drainage hole; 21, frozen electrode plate one; 211, outer layer of heat insulation plate one; 212, inner layer of metal plate one; 213, frozen liquid flow one; 214, frozen liquid inlet one; 215, frozen liquid outlet one; 216, semicylindrical sealing protrusion and groove one; 217, fixed nut one; 22, frozen electrode plate two; 221, outer layer of heat insulation plate two; 222, inner layer of metal plate two; 223, frozen liquid flow two; 224, frozen liquid inlet two; 225, frozen liquid outlet two; 226, anticorrosion coating; 227, semicylindrical sealing protrusion and groove two; 228, fixed nut two; 23, adjustable telescopic rod; 31, temperature-controlled cold bath box one; 311, frozen electrode plate inlet and outlet liquid bellows one; 32, temperature-controlled cold bath box two; 321, frozen electrode plate inlet and outlet liquid bellows two; 33, constant temperature room; 34, LED cold light lamp; 35, movable platform; 36, horizontal telescopic guide rail; 37, vertical support; 38, movable bolt; 41, direct current power supply; 42, wire; 43, wide-mouth bottle; 44, electronic balance; 45, collection box; 46, collection computer; 47, front high-definition digital camera; 48, top high-definition digital camera; 61, high-strength nylon plate outer frame; 62, sand cushion layer; 63, PVC drainage hose; 64, large-pore geotextile; 65, small-pore geotextile. DETAILED DESCRIPTION

[0068] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0069] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0070] Reference Figures 1 to 8 The present application discloses a silt dewatering and decontamination test device simulating freeze-thaw-electroosmosis, comprising:

[0071] The model box module is used for containing the silt sample;

[0072] The electroosmosis module is arranged in the model box module, and is used for applying an electric field to the silt sample and discharging water and heavy metal pollutants in the model box module in the electroosmosis stage;

[0073] The freeze-thaw module, the model box module and the electro-osmosis module are placed in the freeze-thaw module, and the freeze-thaw module is used for removing water in the silt and removing heavy metal pollutants in a freeze-thaw stage and adjusting the environmental temperature in the model box module in an electro-osmosis stage;

[0074] The acquisition module is used for acquiring temperature data in the model box module, electric field data applied by the electro-osmosis module, water sample data of water and heavy metal pollutants and crack change information of the silt sample.

[0075] In use, the silt sample is placed in the model box module, and the model box module is placed in the freeze-thaw module, the silt sample placed in the model box module is subjected to freeze-thaw circulation through the freeze-thaw module, and the silt sample can be subjected to electro-osmosis effect through the electro-osmosis module by applying an electric field to the silt sample, the silt dewatering and pollution removal test can be realized through freeze-thaw and electro-osmosis combination by setting freeze-thaw conditions and electro-osmosis conditions, and the best freeze-thaw condition can be found conveniently, compared with the traditional technology, the device can integrally realize removal of pollutants and water in the silt, the electro-osmosis module and the freeze-thaw module are integrated in a set of device to avoid sample transfer, and the test efficiency is improved.

[0076] As an optional implementation, the model box module comprises:

[0077] The box body;

[0078] The silt sample box 11 is fixed in the box body, and the silt sample box 11 is used for containing the silt sample, and the silt sample box 11 is provided with a viewing window for observation;

[0079] The water collecting area 12 is formed by the silt sample box 11 on one side and the inner wall of the box body, the water collecting area 12 is provided in communication with the silt sample box 11, the electro-osmosis module is arranged in the silt sample box 11, the water collecting area 12 is used for temporarily storing water and heavy metal pollutants discharged from the silt, and a drain hole 121 is formed in one side of the bottom of the water collecting area 12;

[0080] The inverted filter module is in communication with the water outlet end of the silt sample box 11 at the water inlet end, and the water outlet end of the inverted filter module is in communication with the water collecting area 12, and the inverted filter module prevents the water outlet end of the silt sample box 11 from being blocked.

[0081] As an optional implementation, the silt sample box 11 is made of double-layer hollow transparent organic glass around the silt sample box 11 and the bottom, and the silt sample box 11 is located on the front panel and is engraved with grid lines 111.

[0082] The model box module includes a sludge sample box 11 for containing a sludge sample and a water collection area 12 for temporarily storing water and heavy metal pollutants discharged from the sludge. The sludge sample box 11 is open at the top and has a double-layer hollow transparent organic glass around the periphery and at the bottom, which can effectively reduce heat loss during the test; a grid line 111 is drawn on the front panel of the sludge sample box 11, which facilitates subsequent processing of the settlement amount of n grid line intersection points through digital image technology.

[0083] As an optional implementation, the electro-osmosis module includes:

[0084] A first frozen electrode plate 21 and a second frozen electrode plate 22 are installed in the sludge sample box 11, the first frozen electrode plate 21 is located near the water collection area 12, and the first frozen electrode plate 21 is provided with a fluid flow channel; the first frozen electrode plate 21 and the second frozen electrode plate 22 are electrically connected with the acquisition module, and the acquisition module is used to provide electric energy.

[0085] As an optional implementation, the first frozen electrode plate 21 includes:

[0086] An outer thermal insulation plate 211 is provided with a fluid passing channel;

[0087] An inner metal plate 212 is fixedly connected with the outer thermal insulation plate 211, and the structure of the inner metal plate 212 matches that of the outer thermal insulation plate 211; the inner metal plate 212 is used to contact the sludge sample;

[0088] A frozen liquid flow channel 213 is fixedly connected between the outer thermal insulation plate 211 and the inner metal plate 212, and the frozen liquid enters the frozen liquid flow channel 213 through a frozen liquid inlet 214 and is discharged from the frozen liquid flow channel 213 through a frozen liquid outlet 215;

[0089] A semicircular cylindrical sealing protrusion and groove 216 is arranged between the outer thermal insulation plate 211 and the inner metal plate 212, and is used to seal the gap between the outer thermal insulation plate 211 and the inner metal plate 212 after the outer thermal insulation plate 211 and the inner metal plate 212 are spliced.

[0090] As an optional implementation, the second frozen electrode plate 22 includes:

[0091] An outer thermal insulation plate 221 is provided with a fluid passing channel;

[0092] An inner metal plate 222 is fixedly connected with the outer thermal insulation plate 221, and the structure of the outer thermal insulation plate 221 matches that of the inner metal plate 222; the inner metal plate 222 is used to contact the sludge sample, and an anti-electric corrosion coating 226 is applied to the surface of the inner metal plate 222;

[0093] The frozen liquid flow channel two 223 is fixed between the outer layer heat insulation plate two 221 and the inner layer metal plate two 222, the frozen liquid enters the frozen liquid inlet two 224 of the frozen liquid flow channel two 223 and is discharged from the frozen liquid outlet two 225 of the frozen liquid flow channel two 223;

[0094] The semicylindrical sealing protrusion and groove two 227 are arranged between the outer layer heat insulation plate two 221 and the inner layer metal plate two 222, and are used for sealing the gap edge between the outer layer heat insulation plate two 221 and the inner layer metal plate two 222 after the outer layer heat insulation plate two 221 and the inner layer metal plate two 222 are spliced.

[0095] The electroosmosis module comprises a frozen electrode plate one 21, a frozen electrode plate two 22, an adjustable telescopic rod 23, a temperature-controlled cold bath box one 31, a temperature-controlled cold bath box two 32, a constant temperature chamber 33, a direct current power supply 41 and a wire 42.

[0096] The frozen electrode plate one 21 comprises an outer layer heat insulation plate one 211, an inner layer metal plate one 212, a “serpentine” frozen liquid flow channel one 213, a frozen liquid inlet one 214, a frozen liquid outlet one 215, a semicylindrical sealing protrusion and groove one 216 and a fixed nut one 217.

[0097] The frozen electrode plate one 21 is designed as an “inverted E shape”, facilitating the discharge of water and heavy metal pollutants in the test process; the outer layer heat insulation plate one 211 is a copper plate with good electric conductivity and heat conductivity, so that the freezing and thawing process and the electroosmosis process can be realized; the inner layer metal plate one 212 is a nylon plate with high thermal resistance, which can reduce the heat loss in the freezing process and improve the freezing efficiency; the frozen liquid flow channel one 213 is in a “serpentine” structure and is arranged between the inner and outer layers, so that the temperature at both ends of the sample can be more uniform, improving the test precision; the semicylindrical sealing protrusion and groove one 216 is arranged at the upper part and both sides between the inner and outer layers to prevent leakage of the frozen liquid; and the outer layer heat insulation plate one 211 and the inner layer metal plate one 212 are connected to form a whole through the four fixed nuts one 217.

[0098] The frozen electrode plate two 22 comprises an outer layer heat insulation plate two 221, an inner layer metal plate two 222, a frozen liquid flow channel two 223, a frozen liquid inlet two 224, a frozen liquid outlet two 225, an anticorrosive coating 226, a semicylindrical sealing protrusion and groove two 227 and a fixed nut two 228.

[0099] The frozen electrode plate two 22 is different from the frozen electrode plate one 21 in the following aspects:

[0100] The frozen electrode plate two 22 is designed as a "rectangle" to maximize the freezing and conductivity efficiency; an anti-electric corrosion coating is painted around the inner layer, and the anti-electric corrosion coating is selected as graphene, which can effectively slow down the corrosion of the inner layer metal plate in the electric osmosis process, and significantly improve the efficiency of dehydration and pollution removal in the electric osmosis stage; a semicircular cylindrical sealing protrusion and a groove 227 are arranged between the inner and outer layers along the edge, which can prevent the leakage of the frozen liquid.

[0101] The arrangement directions of the frozen liquid flow channel one 213 and the frozen liquid flow channel two 223 in the above two frozen electrode plates are different; the frozen liquid flow channel one 213 of the frozen electrode plate one 21 is arranged vertically, and the frozen liquid flow channel two 223 of the right frozen electrode plate two 22 is arranged horizontally.

[0102] As an optional implementation, the reverse filtration module comprises:

[0103] The high-strength nylon plate outer frame 61 is filled with a sand cushion layer 62, and the particle size of the sand cushion layer 62 increases in turn along the fluid flow direction, which is similar to the design of the earth-rock dam filter layer, and can play a filtering and drainage effect;

[0104] A plurality of PVC drainage flower pipes 63 are buried in the sand cushion layer 62, and the plurality of PVC drainage flower pipes 63 are arranged in a matrix, which can further speed up the drainage of the silt sample;

[0105] The large-aperture geotextile 64 is fixed to one side of the high-strength nylon plate outer frame 61 close to the silt sample box 11, which can prevent soil particles from entering the sand cushion layer to some extent, avoid blockage, and accelerate the entry of water and pollutants into the sand cushion layer to speed up the drainage effect;

[0106] The small-aperture geotextile 65 is fixed to one side of the high-strength nylon plate outer frame 61 close to the catchment area 12, which can effectively prevent particles in the sand cushion layer from being carried out by water during the drainage process.

[0107] As an optional implementation, the freeze-thaw module comprises:

[0108] The constant-temperature room 33;

[0109] The movable platform 35 is slidably arranged at the inside bottom of the constant-temperature room 33 through the horizontal telescopic guide rail 36, the model box module is placed in the movable platform 35, the horizontal telescopic guide rail 36 is located at one end outside the constant-temperature room 33 and is detachably connected with the top end of the vertical support 37 through the movable bolt 38, and the vertical support 37 is arranged perpendicularly to the horizontal telescopic guide rail 36;

[0110] The LED cold light lamp 34 is fixed to the inside top of the constant-temperature room 33;

[0111] The temperature-controlled cold bath box one 31 is located outside the constant temperature room 33, and the inlet end and the outlet end of the temperature-controlled cold bath box one 31 are respectively connected with the refrigerant outlet one 215 and the refrigerant inlet one 214 through the refrigerant inlet-outlet corrugated pipe one 311 of the refrigeration electrode plate;

[0112] The temperature-controlled cold bath box two 32 is located outside the constant temperature room 33, and the inlet end and the outlet end of the temperature-controlled cold bath box two 32 are respectively connected with the refrigerant outlet two 225 and the refrigerant inlet two 224 through the refrigerant inlet-outlet corrugated pipe two 321 of the refrigeration electrode plate.

[0113] The freeze-thaw module includes the temperature-controlled cold bath box one 31 and the temperature-controlled cold bath box two 32, the temperature-controlled cold bath box one 31 is connected with the refrigerant inlet one 214 and the refrigerant outlet one 215 of the refrigeration electrode plate one through the refrigerant inlet-outlet corrugated pipe one 311 and the refrigeration electrode plate one, and the temperature-controlled cold bath box two 32 is connected with the refrigerant inlet two 224 and the refrigerant outlet two 225 of the refrigeration electrode plate two through the refrigerant inlet-outlet corrugated pipe two 321 and the refrigeration electrode plate two, so that the temperature boundary of the silt sample at two ends of the silt sample in the freeze-thaw-electroosmotic process can be accurately controlled.

[0114] The refrigerant outlet of the temperature-controlled cold bath box two 32 is connected with the refrigerant inlet two 224 of the refrigeration electrode plate two 22 close to the bottom side, so that the freezing efficiency of the test can be maximized.

[0115] The constant temperature room 33 is arranged outside the model box module, the temperature-controlled cold bath box, the direct current power supply, the electronic balance, the collection box and the collection computer are arranged outside the constant temperature room 33, and the rest are arranged in the constant temperature room 33.

[0116] One LED cold light lamp 34 is arranged on each of the left side and the right side in the constant temperature room 33, and the light source direction of the LED cold light lamp 34 is 45° with the surface of the silt sample.

[0117] In addition, the constant temperature room 33 is provided with a movable platform 35, the movable platform is located on the horizontal telescopic guide rail 36, the horizontal telescopic guide rail and the vertical support 37 are connected through the movable bolt 38, so that the installation and dismounting of the vertical support are realized.

[0118] As an optional implementation manner, the acquisition module includes:

[0119] The direct current power supply 41 is electrically connected with the inner metal plate two 222 through the wire 42, and the negative pole is electrically connected with the inner metal plate one 212 through another wire 42;

[0120] The front high-definition digital camera 47 and the top high-definition digital camera 48 are respectively arranged on the front side and the top of the silt sample box 11, and the front high-definition digital camera 47 and the top high-definition digital camera 48 are arranged in the constant temperature room 33.

[0121] A wide-mouthed jar 43, the liquid inlet end is connected with the drainage hole 121 through a hose, the wide-mouthed jar 43 is placed on the electronic balance 44;

[0122] A collection box 45, one end is electrically connected with the electronic balance 44, the front high-definition digital camera 47 and the top high-definition digital camera 48, and the other end of the collection box 45 is electrically connected with the collection computer 46.

[0123] The positive and negative poles of the direct current power supply 41 are connected with the inner layer metal plate two 222 of the frozen electrode plate two 22 and the inner layer metal plate one 212 of the frozen electrode plate one 21 through wires 42, for providing the required voltage between the two ends of the sample in the freeze-thaw-electro-osmosis process.

[0124] The data collection module includes the wide-mouthed jar 43, the electronic balance 44, the collection box 45, the collection computer 46, the front high-definition digital camera 47 and the top high-definition digital camera 48.

[0125] The wide-mouthed jar 43 is connected with the drainage hole 121 of the water collecting area, for collecting the water quantity and heavy metal pollutants discharged by the silt sample. The electronic balance 44 is used for real-time monitoring of the drainage quantity of the silt sample. Two high-definition digital cameras are arranged at the front side and the top of the silt sample box, which are the front high-definition digital camera 47 and the top high-definition digital camera 48, respectively. The front high-definition digital camera is used to capture the consolidation process of the silt sample under repeated freeze-thaw cycles, and the top high-definition digital camera is used to monitor the evolution law of surface cracks of the silt sample under freeze-thaw cycles. The electronic balance, the front high-definition digital camera and the top high-definition digital camera are connected with the collection computer 46 through the collection box 45, so as to display and record the above test results in real time.

[0126] A silt dewatering and pollution removal test method for simulating freeze-thaw-electro-osmosis, using the silt dewatering and pollution removal test device for simulating freeze-thaw-electro-osmosis, comprising the following steps:

[0127] S1, preparing a silt sample containing a pollution source, and filling the silt sample in the model box module;

[0128] Measuring the initial moisture content: the silt without heavy metal pollution with a certain initial moisture content is placed in a barrel, and a stirrer is used to stir it uniformly, and three silt samples are taken out, each not less than 50g, and then placed in a 65° oven for drying, and then the initial moisture content is measured.

[0129] Preparation of silt sample: select heavy metal ions as pollution source, the reagent for preparing heavy metal contaminated silt is the solution of corresponding heavy metal compound, set the pollution concentration as X (mass of heavy metal ions: mass of dry silt), design the water content as W; on the basis of the above initial water content, calculate the required mass of heavy metal compound and the mass of deionized water; first dissolve the heavy metal compound in deionized water, then mix it with the silt sample in the barrel by stirring, after stirring, seal it with plastic wrap, and let it stand for 24 hours to ensure uniformity; apply a layer of vaseline along the side wall of the silt sample box, fill the silt in the barrel into the silt sample box to 3 / 4 height, and get the silt sample with heavy metal pollution concentration X and water content W; finally, place the model box module into the constant temperature room 33.

[0130] S2, assemble and set the temperature gradient to be executed in the freeze-thaw module, perform freeze-thaw cycle test, and obtain test data and images through the acquisition module;

[0131] S3, when performing N times of freeze-thaw cycle test under different freezing temperature gradients, change the temperature gradient to be executed in step S2, and then perform freeze-thaw cycle test;

[0132] A high-definition digital camera is arranged in front of and behind the silt sample box 11, the height, angle and distance of the front high-definition digital camera 47 and the top high-definition digital camera 48 are adjusted, so that the grid lines 111 in front of the silt sample box can be clearly displayed in the center of the screen of the front high-definition digital camera 47, and the surface of the silt sample in the silt sample box 11 can be clearly displayed in the center of the screen of the top high-definition digital camera 48.

[0133] Temperature gradient setting: first, set the temperature of the constant temperature room 33 to a constant positive temperature T0; turn on the temperature control cold bath box two 32 and set it to freezing temperature T2, and keep the temperature control cold bath box one 31 set to positive temperature T1, that is, the left side is the warm end,

[0134] the right side is the cold end, so that the temperature of the left side cold freezing liquid flow channel one 213 and the temperature of the right side cold freezing liquid flow channel two 223 form a stable temperature gradient grad(T)=(T1-T2) / L (L is the spacing between the two cold electrode plates).

[0135] One freeze-thaw cycle: the sample is continuously frozen for 12 hours under the temperature gradient formed in the above step, then the temperature of the two temperature control cold bath boxes is adjusted to positive temperature T3, so that the sample is continuously melted at positive temperature T3 for 12 hours, thereby forming a freeze-thaw cycle; during the melting process, the consolidation process and surface crack evolution law of the silt sample are monitored in real time through the high-definition digital camera, and the total amount of drainage of the silt sample is monitored in real time through the electronic balance.

[0136] N times of freeze-thaw cycle: repeat the above steps to complete N times of freeze-thaw cycle test.

[0137] S4, determining the optimal freezing temperature gradient and the number of freeze-thaw cycles after analyzing the data;

[0138] The determination of the optimal freezing temperature gradient and the number of freeze-thaw cycles comprises the following steps:

[0139] According to the image results of N freeze-thaw cycles under different freezing temperature gradients, the optimal freezing temperature gradient and the number of freeze-thaw cycles can be determined, comprising the following steps:

[0140] Constructing a first objective function: based on the image data captured by the front high-definition digital camera, using image processing technology to analyze the settlement amount change of the intersection points of the first n grid lines of the silt sample after N freeze-thaw cycles under different freezing temperature gradients, and constructing a first objective optimization function with the settlement amount as the independent variable:

[0141]

[0142] T is the freezing temperature gradient;

[0143] N is the number of freeze-thaw cycles;

[0144] n is the number of intersection points of the grid lines on the surface of the silt sample;

[0145] hi is the initial height value of the i-th intersection point of the grid lines;

[0146] hi is the height value of the i-th intersection point of the grid lines of the silt sample after freezing and thawing;

[0147] Constructing a second objective function: processing the surface images of the silt sample obtained by the top high-definition digital camera after N freeze-thaw cycles under different freezing temperature gradients, calculating the area of the cracks by counting the number of pixel points, and constructing a second objective optimization function with the crack area as the independent variable:

[0148] g(T,N)=1-r

[0149] T is the freezing temperature gradient;

[0150] N is the number of freeze-thaw cycles;

[0151] r is the crack rate of the silt sample after freezing and thawing;

[0152] Constructing a unified multi-objective function: the first objective function and the second objective function are combined to establish a unified multi-objective optimization function, and the optimal freezing temperature gradient and the number of freeze-thaw cycles can be obtained when the function reaches the minimum value:

[0153]

[0154] a is the weight coefficient of the first objective function, and b is the weight coefficient of the second objective function.

[0155] S5, on the basis of the freeze-thaw test of the optimal freezing temperature gradient and the number of freeze-thaw cycles, starting the electro-osmosis module to carry out a drainage process, and acquiring test data by the acquisition module;

[0156] The direct current power supply is turned on, the voltage value of the direct current power supply is set according to the potential gradient of 1 V / cm, the electro-osmosis time is 24 h, and the electronic balance 44 is used to monitor the change of the drainage amount of the silt sample in real time during the electro-osmosis process.

[0157] S6, test result processing and analysis.

[0158] After the test is completed, the solution in the wide-mouth bottle 43 is taken out, the content of heavy metals and the water amount in the solution are measured, the total energy consumption values of the freeze-thaw and electro-osmosis stages are calculated, the water amount drained and the heavy metal amount removed per unit energy consumption are obtained, a certain mass of silt samples at different sections from left to right in the silt sample box 11 are taken out for drying, the water content of the silt sample is measured, and the dehydration efficiency of different sections from left to right in the silt sample box 11 is calculated; the silt samples after drying are ground and sieved, the occurrence form of heavy metals in the silt sample is determined according to the Tessier five-step extraction method, and then the concentrations of various forms of heavy metals in the silt sample are measured by using an atomic absorption spectrophotometer, so that the residual concentration and removal efficiency of heavy metal ions at different sections from left to right in the silt sample box are calculated.

[0159] The distance between the frozen electrode plate one 21 and the frozen electrode plate two 22 can be changed by three adjustable telescopic rods, so that the influence of different temperature gradients and potential gradients on the silt dehydration and pollution removal effect can be explored.

[0160] The flexible control of the test target temperature in the temperature-controlled cold bath box one 31 and the temperature-controlled cold bath box two 32 can also enable the silt freeze-thaw dehydration and pollution removal test under various complex environmental boundary conditions such as bidirectional freezing and bidirectional thawing.

[0161] During the simulation of the silt sample cycle freeze-thaw process, the temperature of the constant temperature room 33 remains unchanged and is always positive, and the target temperature is preferably 2-5 DEG C.

[0162] A large number of cracks will be generated in the silt sample in the later electro-osmosis stage, the silt sample is subjected to secondary freeze-thaw by opening the temperature-controlled cold bath box one 31 and the temperature-controlled cold bath box two 32, and the method of changing the freezing direction or the freezing mode can make the surface partial cracks of the silt sample heal, so that the dehydration and pollution removal efficiency in the electro-osmosis stage can be improved.

[0163] Compared with the traditional technology, the present application has the following effects:

[0164] 1. The frozen electrode plate in the present application is divided into two layers, the inner layer is a high thermal conductivity copper plate, and the outer layer is a high thermal resistance nylon plate, and a "serpentine" frozen liquid channel is arranged between the inner and outer layers, which can realize freezing and thawing process and electroosmosis process.

[0165] 2. The frozen electrode plate in the present application comprises left and right two blocks, the left frozen electrode plate is designed as "inverted E shape", which is helpful for the discharge of sample moisture and heavy metal pollutants, and the right frozen electrode plate is designed as "rectangle", and the inner layer surface is painted with an anti-electric corrosion coating, which can significantly improve the freezing and conductivity efficiency.

[0166] 3. The sample box in the present application is opened at the top, and the periphery and bottom are made of double-layer hollow transparent organic glass, which can reduce the heat loss in the test; in addition, through flexible control of the target temperature of the constant temperature room and the left and right two temperature-controlled cold bath boxes, a variety of complex environment boundary underlaying sludge dewatering and pollution removal tests such as one-way freezing, two-way freezing, two-way thawing and the like can be carried out, and the double-layer hollow design of the sample box combined with the inner and outer combined temperature control mode greatly improves the test precision.

[0167] 4. In the sand cushion layer, PVC drainage flower pipes are uniformly arranged along the height and horizontal direction, the drainage flower pipes are composed of horizontal sections and tail inclined sections, which can slow down the clogging problem of the inverse filtration module during the test.

[0168] 5. In the present application, intelligent means such as coupling digital image tracking and real-time drainage monitoring are used, and a "best freezing-thawing cycle number" and "best freezing temperature gradient" determination method is proposed by using multi-objective optimization algorithm.

[0169] 6. When a large number of cracks are generated in the sludge sample in the later stage of electroosmosis, the temperature-controlled cold bath box can be opened to carry out secondary freezing and thawing of the sample, and the method of changing the freezing direction or freezing mode is used to heal part of the cracks on the surface of the sludge sample, and further carrying out secondary electroosmosis test can significantly improve the dewatering and pollution removal efficiency in the electroosmosis stage.

[0170] 7. The test device used in the present application can carry out the dewatering and pollution removal test of sludge under the coupling action of freezing-thawing-electroosmosis, realizes the intelligentization and integration of sludge deep dewatering and pollution removal, has low device cost, simple operation method, and high test result reliability.

[0171] 8. The present application adopts the freezing-thawing-electroosmosis coupling mode, combines digital image processing technology and multi-objective optimization algorithm, realizes the intelligentization and integration of dewatering and pollution removal, and significantly improves the efficiency of sludge dewatering and pollution removal; in addition, the composite temperature control mode of the constant temperature room combined with the temperature-controlled cold bath box not only can simulate various complex temperature boundaries, but also can improve the test precision and reliability of the test results.

[0172] In the description of the present application, it needs to be understood that the terms "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0173] The above-described embodiments are only to describe the preferred modes of the present application, and not to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A test device for simulating freeze-thaw-electroosmotic dewatering and decontamination of sludge, characterized by, The application relates to a model box module for containing a silt sample; an electro-osmosis module arranged in the model box module, the electro-osmosis module being used for applying an electric field to the silt sample and discharging water and heavy metal pollutants in the model box module in an electro-osmosis stage; a freeze-thaw module, the model box module and the electro-osmosis module being placed in the freeze-thaw module, the freeze-thaw module being used for removing water and heavy metal pollutants in the silt in a freeze-thaw stage and adjusting the environmental temperature in the model box module in the electro-osmosis stage; and an acquisition module for acquiring temperature data in the model box module, electric field data applied by the electro-osmosis module, water sample data of the water and heavy metal pollutants and crack change information of the silt sample. The model box module comprises a box body, a silt sample box (11) fixedly connected in the box body, the silt sample box (11) being used for containing a silt sample, the silt sample box (11) being provided with a viewing window for observation, a water collecting area (12) formed by one side of the silt sample box (11) and the inner wall of the box body, the water collecting area (12) being arranged in communication with the silt sample box (11), the electro-osmosis module being arranged in the silt sample box (11), the water collecting area (12) being used for temporarily storing the water and heavy metal pollutants discharged from the silt, and a drain hole (121) being formed in one side of the bottom of the water collecting area (12). The electro-osmosis module comprises a refrigeration electrode plate one (21) and a refrigeration electrode plate two (22) installed in the silt sample box (11), the refrigeration electrode plate one (21) being located on the side close to the water collecting area (12), the refrigeration electrode plate one (21) being provided with a channel for fluid flow, the refrigeration electrode plate one (21) and the refrigeration electrode plate two (22) being electrically connected with the acquisition module, and the acquisition module being used for providing electric energy. The refrigeration electrode plate one (21) comprises an outer heat insulation plate one (211) provided with a channel for fluid flow, an inner metal plate one (212) fixedly connected with the outer heat insulation plate one (211) and matched with the structure of the outer heat insulation plate one (211), the inner metal plate one (212) being used for contacting with the silt sample, a refrigeration liquid flow channel one (213) fixedly connected between the outer heat insulation plate one (211) and the inner metal plate one (212), refrigeration liquid entering the refrigeration liquid flow channel one (213) through a refrigeration liquid inlet one (214) and being discharged from the refrigeration liquid flow channel one (213) through a refrigeration liquid outlet one (215). ​ ​ ​ ​ ​ ​ 2. The apparatus for testing dewatering and decontamination of sludge by simulating freeze-thaw-electroosmosis according to claim 1, characterized in that: ​ 3. The apparatus for simulating freeze-thaw-electro-osmotic dewatering and decontamination of silt according to claim 1, characterized in that, ​ ​ 4. The apparatus for simulating freeze-thaw-electro-osmotic dewatering and decontamination of silt according to claim 3, characterized in that, ​ ​ ​ ​ Half-cylindrical sealing protrusion and groove one (216) is arranged between the outer layer heat insulation plate one (211) and the inner layer metal plate one (212), and is used for sealing the gap edge between the outer layer heat insulation plate one (211) and the inner layer metal plate one (212) after the outer layer heat insulation plate one (211) and the inner layer metal plate one (212) are spliced.

5. The apparatus for simulating freeze-thaw-electro-osmotic dewatering and decontamination of silt according to claim 4, wherein The frozen electrode plate two (22) comprises: An outer layer heat insulation plate two (221); An inner layer metal plate two (222) is fixedly connected with the outer layer heat insulation plate two (221), the outer layer heat insulation plate two (221) and the inner layer metal plate two (222) are matched in structure, the inner layer metal plate two (222) is used for being in contact with the silt sample, and an anti-electric corrosion coating (226) is coated on the surface of the inner layer metal plate two (222); A frozen liquid flow channel two (223) is fixedly connected between the outer layer heat insulation plate two (221) and the inner layer metal plate two (222), frozen liquid enters the frozen liquid flow channel two (223) through a frozen liquid inlet two (224) and is discharged from a frozen liquid outlet two (225) of the frozen liquid flow channel two (223); Half-cylindrical sealing protrusion and groove two (227) are arranged between the outer layer heat insulation plate two (221) and the inner layer metal plate two (222), and are used for sealing the gap edge between the outer layer heat insulation plate two (221) and the inner layer metal plate two (222) after the outer layer heat insulation plate two (221) and the inner layer metal plate two (222) are spliced.

6. The apparatus for simulating freeze-thaw-electro-osmotic dewatering and decontamination of silt according to claim 1, wherein The anti-filtering module comprises: A high-strength nylon plate outer frame (61) is filled with a sand cushion layer (62) inside, and the particle size of the sand cushion layer (62) increases in turn along the fluid flow direction; A plurality of PVC drainage flower pipes (63) are embedded in the sand cushion layer (62), and a plurality of the PVC drainage flower pipes (63) are arranged in a matrix; A large-aperture geotextile (64) is fixedly connected to one side of the high-strength nylon plate outer frame (61) close to the silt sample box (11); A small-aperture geotextile (65) is fixedly connected to one side of the high-strength nylon plate outer frame (61) close to the catchment area (12).

7. The apparatus for simulating freeze-thaw-electro-osmotic dewatering and decontamination of silt according to claim 5, wherein The freeze-thaw module comprises: A constant-temperature room (33); A movable platform (35) is slidably arranged at the inside bottom of the constant-temperature room (33) through a horizontal telescopic guide rail (36), the model box module is placed in the movable platform (35), one end of the horizontal telescopic guide rail (36) located outside the constant-temperature room (33) is detachably connected with the top end of a vertical support (37) through a movable bolt (38), and the vertical support (37) is arranged perpendicularly to the horizontal telescopic guide rail (36); An LED cold light lamp (34) is fixed to the inside top of the constant-temperature room (33); A temperature control cold bath box one (31) is located outside the constant-temperature room (33), and the inlet end and the outlet end of the temperature control cold bath box one (31) are respectively communicated with the frozen liquid outlet one (215) and the frozen liquid inlet one (214) through a frozen electrode plate inlet and outlet liquid corrugated pipe one (311). A temperature-controlled cold bath box two (32) is located outside the constant temperature chamber (33), and the inlet end and the outlet end of the temperature-controlled cold bath box two (32) are respectively connected with the refrigerant outlet two (225) and the refrigerant inlet two (224) through refrigerant inlet and outlet corrugated pipes two (321).

8. A method for simulating the dewatering and decontamination of sludge by freeze-thaw electroosmosis, using the device for simulating the dewatering and decontamination of sludge by freeze-thaw electroosmosis according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: Filling a silt sample containing a pollution source in the model box module; Controlling the freeze-thaw module to adjust the temperature boundary of the silt sample at both ends in the model box module and the environmental temperature, carrying out silt dewatering and pollution removal tests under different freezing temperature gradients and different freeze-thaw cycle numbers, and determining the optimal freezing temperature gradient and freeze-thaw cycle number by using a multi-objective algorithm; After the freeze-thaw cycle test under the optimal freeze-thaw conditions determined above, controlling the electro-osmosis module to carry out an electro-osmosis test to continue to discharge water and heavy metal pollutants; Obtaining water sample data of water and heavy metal pollutants in the freeze-thaw stage and the electro-osmosis stage by the acquisition module, and calculating the dewatering efficiency of the silt and the removal efficiency of the heavy metal ions.

9. The method according to claim 8, wherein, The step of determining the optimal freezing temperature gradient and freeze-thaw cycle number by the multi-objective algorithm comprises: According to the image data captured by the front high-definition digital camera in the acquisition module, the settlement amount change of the intersection points of the n grid lines in the front part of the silt sample after N freeze-thaw cycles under different freezing temperature gradients is analyzed by using image processing technology, and a first target optimization function is constructed with the settlement amount as the independent variable; The surface images of the silt sample after N freeze-thaw cycles under different freezing temperature gradients are processed by using the top high-definition digital camera in the acquisition module, the area of the cracks is calculated by counting the number of pixel points, and a second target optimization function is constructed with the crack area as the independent variable; The first target function and the second target function are combined to establish a unified multi-objective optimization function, and the optimal freezing temperature gradient and freeze-thaw cycle number can be obtained when the function reaches a minimum value.

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