CN211275871U - Heavy metal contaminated soil's prosthetic devices - Google Patents
Heavy metal contaminated soil's prosthetic devices Download PDFInfo
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- CN211275871U CN211275871U CN201921781557.8U CN201921781557U CN211275871U CN 211275871 U CN211275871 U CN 211275871U CN 201921781557 U CN201921781557 U CN 201921781557U CN 211275871 U CN211275871 U CN 211275871U
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Abstract
The utility model belongs to the technical field of soil restoration, concretely relates to prosthetic devices of heavy metal contaminated soil. The device comprises a leaching system and a membrane distillation system; the device is used for restoring the polluted soil by combining the leaching system with the membrane distillation system for the first time, and compared with the prior art, the device has the advantages of small volume, high efficiency, low labor intensity, simple structure, easy realization of operation, small water consumption, high efficiency, stability, economy and environmental protection. The membrane distillation system in the device includes the power, crystallizer and at least one membrane distillation array structure, adopt the power to provide the signal of telecommunication for membrane distillation array structure, can restrain the microorganism in the waste liquid and form the contaminated layer at the face of membrane, prevent that inorganic pollution from forming the crystallization at the face of membrane, reduce the membrane material performance, better anti membrane pollution ability has, also can effectively separate the solution that is rich in heavy metal ion simultaneously, can carry out crystallization recovery to the waste liquid after the separation again, have high efficiency, economy, the advantage of environmental protection.
Description
Technical Field
The utility model belongs to the technical field of soil restoration, concretely relates to prosthetic devices of heavy metal contaminated soil.
Background
At present, the soil in China is seriously polluted by heavy metal, more than 10 percent of cultivated lands are polluted by heavy metal, so that the yield of grains is reduced by about one thousand million tons every year, the amount of inedible grains is up to one thousand two million tons due to heavy metal pollution, and at least two billion yuan of economic loss is caused.
The soil remediation technology mainly comprises three methods, namely bioremediation, chemical remediation and physical remediation, and is safe, low in cost and free of secondary pollution, but the bioremediation condition is strict and is not suitable for treating heavy metal pollution; the chemical remediation technology is easy to operate, good in effect and good in long-acting property, but leaching methods and soil property improvement methods are mostly adopted in the chemical remediation technology to remediate heavy metals in soil, but the leaching methods generate a large amount of waste liquid, the subsequent treatment is troublesome, and secondary pollution is caused; the physical remediation technology is a method for separating pollutants from soil by adopting a certain technology and means to recover the usable value of the soil, is simple to operate and good in effect, is mainly a technology for remedying heavy metals, but has the advantages of higher cost, low efficiency and higher labor intensity. Therefore, research on a new remediation method for the contaminated soil is urgently needed in the technical field of heavy metal contaminated soil.
Disclosure of Invention
Therefore, the to-be-solved technical problem of the utility model lies in overcoming the prosthetic with high costs of soil among the prior art, inefficiency, intensity of labour are big and prosthetic devices' structure is complicated, easily produce defects such as secondary pollution to a prosthetic devices and repair method of heavy metal contaminated soil are provided.
Therefore, the utility model provides the following technical scheme.
The utility model provides a heavy metal contaminated soil restoration device, which comprises,
the leaching system comprises a spiral conveyor belt arranged inside the leaching system, a spraying device arranged at the top of the leaching system and a liquid storage tank arranged at the bottom of the leaching system;
a membrane distillation system comprising, in combination,
at least one membrane distillation array structure in communication with the reservoir;
a power supply to provide an electrical signal to the membrane distillation array structure;
and the crystallizer is communicated with a liquid phase outlet of the membrane distillation array structure.
The membrane distillation array structure comprises a membrane distillation array structure,
the membrane distillation components are internally provided with distillation membranes and electrodes, the distillation membranes and the electrodes are respectively connected with the power supply, and a gas phase area and a liquid phase area are respectively arranged on two sides of each distillation membrane;
the water distribution grooves are arranged at two ends of the distillation membrane, are communicated with the liquid storage tank and are simultaneously communicated with the liquid phase area;
and the steam collector is arranged at the bottom of the membrane distillation assembly and is communicated with the gas phase area.
The membrane distillation assembly further comprises a flow guide net arranged on one side or two sides of the distillation membrane.
The membrane distillation system also comprises a condensing device and a pressure control device, wherein the pressure control device is communicated with the steam collector through the condensing device.
The spraying device comprises a doser, a spraying pool and a nozzle.
The pressure control device is communicated with the doser.
And a liquid outlet of the crystallizer is communicated with the liquid storage tank.
The membrane distillation system also comprises a circulating pump and a first heating device, and the liquid storage tank is communicated with the membrane distillation array structure through the circulating pump and the first heating device.
The membrane distillation array structure is two, and a second heating device is further arranged between the two membrane distillation array structures.
The spiral conveyor belt is made of hydrophilic materials or materials provided with a plurality of through holes;
the number of layers of the spiral conveyor belt is 5-15;
the aperture of the through hole is 0.5-2.0 mm.
The distillation membrane is a conductive distillation membrane.
The invention also provides a repairing method of the heavy metal contaminated soil repairing device, which comprises the steps of obtaining a heavy metal ion-rich solution after the heavy metal contaminated soil is washed by the leacheate;
carrying out membrane distillation separation on the solution rich in heavy metal ions to obtain a gas phase and a liquid phase;
and crystallizing the liquid phase to obtain crystals and waste liquid.
When the solution rich in heavy metal ions is subjected to membrane distillation separation, the voltage of the power supply is 1.2-5.0V, and the frequency is 200kHz-20 MHz.
The pressure of the gas phase is less than 1 atmosphere; the flow rate of the heavy metal ion-rich solution is 0.5-5 cm/S.
Heating the solution rich in heavy metal ions and then performing membrane separation treatment, wherein the heating temperature is 40-80 ℃;
and the gas phase is condensed and then mixed with the leacheate, and the condensation temperature is 5-15 ℃.
And mixing the waste liquid with the solution rich in the heavy metal ions, and performing repeated membrane distillation separation.
And the solution rich in heavy metal ions is subjected to two-stage membrane distillation separation treatment.
The preparation method of the distillation membrane comprises the following steps,
uniformly mixing the carbon nano tube, the dispersing agent and the solvent to obtain homogenate;
adding polyvinylidene chloride into the homogenate, heating in a water bath and stirring to obtain slurry;
and spraying the slurry on the surface of the polytetrafluoroethylene membrane by adopting a spraying method, and drying to obtain the distillation membrane.
The mass ratio of the carbon nano tube to the dispersing agent is (18-22): 1;
the temperature of the water bath heating is 45-55 ℃, and the stirring speed is 3-5 r/s;
the dispersant is carbon nanotube alcohol; the solvent is ethanol;
the thickness of the polytetrafluoroethylene surface slurry is 20-50 μm.
The leacheate is KH2PO4、NaH2PO4、CaCl2At least one aqueous solution of (a);
the mole fraction of the leacheate is 0.1-2.0 mol/L.
The utility model discloses technical scheme has following advantage:
1. the utility model provides a heavy metal contaminated soil remediation device, which comprises a leaching system and a membrane distillation system; the device is used for restoring the polluted soil by combining the leaching system with the membrane distillation system for the first time, and compared with the prior art, the device has the advantages of small volume, high efficiency, low labor intensity, simple structure, easy realization of operation, small water consumption, high efficiency, stability, economy and environmental protection. The leaching system in the device adopts the conveying belt with the spiral structure to carry out leaching on the soil while conveying the soil, and the soil is leached for multiple times, so that heavy metal ions in the soil can be effectively removed, the leaching efficiency is improved, and the size of the leaching system can be reduced by adopting the conveying belt with the spiral structure; the membrane distillation system in the device includes the power, crystallizer and at least one membrane distillation array structure, provide the signal of telecommunication for membrane distillation array structure through adopting the power, can restrain the microorganism in the waste liquid and form the contaminated layer at the face of membrane, prevent that inorganic pollution from forming the crystallization at the face of membrane, reduce the performance of membrane material, make membrane distillation system have better anti membrane pollution ability, also can effectively separate the solution that is rich in heavy metal ion simultaneously, can carry out crystallization recovery to the waste liquid after the separation again, have high efficiency, economy, the advantage of environmental protection.
2. The utility model provides a heavy metal contaminated soil remediation device, wherein the membrane distillation array structure comprises a membrane distillation component, a water distribution tank and a steam collector; the membrane distillation array structure comprises a membrane distillation assembly, and the membrane distillation assembly has good membrane pollution resistance, can effectively separate heavy metal ion-rich solution, and has good separation effect. In the device, voltage is applied to the distillation membrane and the electrode, so that the formation of a biological pollution layer on the membrane surface by microorganisms in the waste liquid can be inhibited, the formation of crystals on the membrane surface by inorganic pollution can be prevented, the performance of a membrane material is reduced, and the membrane distillation assembly has better membrane pollution resistance.
3. The repairing method provided by the utility model comprises the steps that the leaching solution is used for leaching the heavy metal polluted soil to obtain a solution rich in heavy metal ions; carrying out membrane distillation separation on the solution rich in heavy metal ions to obtain a gas phase and a liquid phase; and crystallizing the liquid phase to obtain crystals and waste liquid. The method can effectively reduce the content of heavy metals in the soil, realizes the recycling of the heavy metals, and is economical and environment-friendly.
The method is beneficial to separating the gas phase from the heavy metal ion solution by controlling the heating temperature and the condensation temperature; the flow rate is controlled, so that the energy consumption and the water production rate are well balanced, the water production rate is high due to the over-high flow rate, the heat energy utilization efficiency is low, the energy consumption is high, and the problem can be avoided by controlling the flow rate;
the method limits the components and preparation of the distillation membrane, the distillation membrane is a hydrophobic film, and is helpful for preventing heavy metal ions from entering a gas phase area, so that the problem of secondary pollution is avoided;
the method can reduce the adhesion of pollutants on the soil surface, promote the dissolution of the pollutants on the soil surface and achieve the aim of repairing the soil by selecting the specific leacheate.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the technical solutions in the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a device for remediating heavy metal contaminated soil according to embodiment 1 of the present invention;
fig. 2 is a schematic structural diagram of a leaching system in embodiment 1 of the present invention;
FIG. 3 is a schematic structural view of a membrane distillation system in example 1 of the present invention;
FIG. 4 is a schematic view of the internal structure of a membrane distillation module in example 1 of the present invention;
description of reference numerals:
1-leaching system; 2-a membrane distillation system;
11-a liquid storage tank; 12-a spraying device; 13-a soil reservoir; 14-a spiral conveyor belt; 15-leaching the system housing; 21-a circulating pump; 22-first heating means; 23-a first membrane distillation array configuration; 24-a power supply; 25-a crystallizer; 26-a condensing unit; 27-a pressure control device; 28-a second membrane distillation array configuration; 29-a second heating device;
121-a spray tank; 122-a spray head; 123-a medicine adding device; 231-a water distribution tank; 232-a steam collector; 233-membrane distillation assembly; 234-heavy metal ion rich solution inlet; 235-a first waste outlet; 236-gas phase exhaust port; 237-a first wire; 238-second conductive line;
2331-drainage nets; 2332-membrane distillation module housing; 2333-distillation of membranes; 2334-electrodes.
Detailed Description
The following examples are provided for better understanding of the present invention, and are not limited to the best mode, and do not limit the scope and content of the present invention, and any product that is the same or similar to the present invention, which is obtained by combining the features of the present invention with other prior art or the present invention, falls within the scope of the present invention.
The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.
Example 1
The embodiment provides a device and a method for repairing heavy metal contaminated soil, the device is shown in figure 1 and comprises,
the leaching system 1 is used for leaching heavy metal contaminated soil to obtain a solution rich in heavy metal ions; as shown in fig. 2, comprises a liquid storage tank 11 rich in heavy metal ion solution, a spraying device 12, a soil storage 13, a spiral conveyor belt 14 and a leaching system shell 15; the spraying device 12 comprises a spraying tank 121, a spray head 122 and a chemical adding device 123, an eluent is stored in the spraying tank 121, the spraying device 12 is arranged at the top of the leaching system 1, the liquid storage tank is arranged at the bottom of the leaching system, the heavy metal contaminated soil is conveyed from bottom to top by the spiral conveyor belt 14, the eluent passes through the spray head 122 and then passes through the spiral conveyor belt from top to bottom, the heavy metal contaminated soil is leached for multiple times, the soil is leached, a solution rich in heavy metal ions is obtained, the solution is collected in the liquid storage tank 11 rich in heavy metal ions, and the leached soil is conveyed to the soil storage tank 13; in this embodiment, the spiral conveyer belt is the non-woven fabrics material that permeates water, and the leacheate can permeate the non-woven fabrics and from top to bottom transmit in the leaching system, and the number of piles sets up to 10.
The membrane distillation system 2, as shown in fig. 1, includes a crystallizer 25, two membrane distillation array structures (including a first membrane distillation array structure 23 and a second membrane distillation array structure 28), a pressure control device (in this embodiment, a vacuum pump) 27, a power supply (in this embodiment, a high-frequency electrical signal generator) 24, a first heating device 22, a second heating device 29, a circulating pump 21, and a condensing device 26, wherein the crystallizer is communicated with a liquid phase outlet of the membrane distillation array structure, and a liquid outlet of the crystallizer is communicated with a liquid storage tank, and is used for performing repeated membrane distillation separation on waste liquid; the first membrane distillation array structure 23 includes a plurality of membrane distillation assemblies 233 (20 membrane distillation assemblies in this embodiment), a water distribution tank 231 and a steam collector 232, as shown in fig. 3, the water distribution tank 231 is disposed at two ends of the instant distillation membrane and is communicated with the liquid storage tank, and the steam collector is disposed at the bottom of the membrane distillation assemblies; a distillation membrane 2333, an electrode 2334 and a flow guide net 2331 are arranged in the membrane distillation assembly 233, the flow guide net is arranged on two sides of the distillation membrane, so that a gas phase region and a liquid phase region are formed on two sides of the distillation membrane, the liquid phase region is communicated with the water distribution tank, the gas phase region is communicated with the steam collector, the distillation membrane and the electrode are respectively connected with the high-frequency electric signal generator through a first lead 237 and a second lead 238, so that the distillation membrane and the electrode are charged with voltage, as shown in fig. 4; the heavy metal ion-rich solution is heated by the circulating pump 21 and the first heating device 22, then passes through the heavy metal ion-rich solution inlet 234, and then enters the water distribution tank 231 of the first membrane distillation array structure 23, under the action of the water distribution tank 231, the heavy metal ion-rich solution is evenly distributed to the membrane distillation assembly 233, the heavy metal ion-rich solution is separated by the distillation membrane to obtain a gas phase (water vapor) and a liquid phase (first waste liquid), the membrane distillation assembly is separated by the distillation membrane to form a gas phase region and a liquid phase region, the first waste liquid is discharged from the first waste liquid outlet 235, passes through the second heating device 29, and then enters the second membrane distillation array structure 28 to be separated again to obtain a second waste liquid and a gas phase (water vapor); under the action of a vacuum pump, the pressure in the gas phase area is lower than 1 atmosphere, the steam pressure difference on two sides of the distillation membrane is increased, water in the solution rich in heavy metal ions is facilitated to form steam, the steam is discharged, the water producing efficiency is improved, the steam is pumped out by the vacuum pump, is discharged from a gas phase discharge port 236 and enters a steam collector, then enters a medicine adding device 123 after passing through a condensing device 26 and the vacuum pump, is prepared into leacheate again, and flows back to the spraying pool 121 for recycling; and the second waste liquid enters a crystallizer 25, the crystallizer can accelerate the crystallization speed of the second waste liquid, crystals and third waste liquid are obtained after the second waste liquid is crystallized, the crystals are recovered, and the third waste liquid is circulated to a liquid storage tank 11 rich in heavy metal ion solution for circular separation. The distillation membrane and the electrode in the membrane distillation assembly are respectively connected with a high-frequency electric signal generator, as shown in fig. 4, so that the distillation membrane and the electrode are both loaded with voltage, in the embodiment, the voltage is 3V, the frequency is 10MHz, and the high-frequency electric field can inhibit microorganisms in the waste liquid from forming a biological pollution layer on the membrane surface of the distillation membrane, prevent inorganic pollution from forming crystals on the membrane surface, and reduce the performance of the membrane material.
Wherein the leacheate is KH with the mole fraction of 1mol/L2PO4The flow rate of the solution rich in heavy metal ions is 2 cm/S;
the method for preparing the distillation membrane used in this example includes,
(1) mixing 20g of multi-walled carbon nanotube and 2g of carbon nanotube alcohol dispersant in 20ml of alcohol, and ultrasonically oscillating for 30min to obtain homogenized slurry;
(2) adding 10g of polyvinylidene chloride into the homogenate, and stirring for 2 hours at the water bath condition of 50 ℃ at the stirring speed of 4r/s to obtain slurry;
(3) spraying the slurry on the surface of a polytetrafluoroethylene film by a spraying method, wherein the spraying thickness is 30 microns; and then placing the membrane in a ventilation environment at 40 ℃ for 36h, and completely drying to obtain the distillation membrane which is a conductive hydrophobic membrane.
Example 2
The embodiment provides a device and a method for repairing heavy metal contaminated soil, the device is shown in figure 1 and comprises,
the leaching system 1 is used for leaching heavy metal contaminated soil to obtain a solution rich in heavy metal ions; as shown in fig. 2, comprises a liquid storage tank 11 rich in heavy metal ion solution, a spraying device 12, a soil storage 13, a spiral conveyor belt 14 and a leaching system shell 15; the spraying device 12 comprises a spraying tank 121, a spray head 122 and a chemical adding device 123, the leacheate is stored in the spraying tank 121, the spraying device 12 is arranged at the top of the leaching system 1, the liquid storage tank is arranged at the bottom of the leaching system, the heavy metal contaminated soil is conveyed from bottom to top by the spiral conveyor belt 14, the leacheate passes through the spray head 122 and then passes through the spiral conveyor belt from top to bottom, the heavy metal contaminated soil is leached for multiple times, the soil is leached, a solution rich in heavy metal ions is obtained, the solution is collected in the solution storage tank 11 rich in heavy metal ions, and the leached soil is conveyed to the soil storage tank 13; in this embodiment, the spiral conveyer belt is for being provided with the material of a plurality of aperture 1.5mm through-holes (the drive belt is the teflon conveyer belt), and the leacheate can pass through the through-hole and from top to bottom transmit in the drip washing system, and the number of piles sets up to 10 layers.
The membrane distillation system 2, as shown in fig. 1, includes a crystallizer 25, two membrane distillation array structures (including a first membrane distillation array structure 23 and a second membrane distillation array structure 28), a pressure control device (in this embodiment, a vacuum pump) 27, a power supply (in this embodiment, a high-frequency electrical signal generator) 24, a first heating device 22, a second heating device 29, a circulating pump 21, and a condensing device 26, wherein the crystallizer is communicated with a liquid phase outlet of the membrane distillation array structure, and a liquid outlet of the crystallizer is communicated with a liquid storage tank, and is used for performing repeated membrane distillation separation on waste liquid; the first membrane distillation array structure 23 includes a plurality of membrane distillation assemblies 233 (20 membrane distillation assemblies in this embodiment), a water distribution tank 231 and a steam collector 232, as shown in fig. 3, the water distribution tank 231 is disposed at two ends of the distillation membrane and is communicated with the liquid storage tank, and the steam collector is disposed at the bottom of the membrane distillation assemblies; a distillation membrane 2333, an electrode 2334 and a flow guide net 2331 are arranged in the membrane distillation assembly 233, the flow guide net is arranged on two sides of the distillation membrane, so that a gas phase region and a liquid phase region are formed on two sides of the distillation membrane, the liquid phase region is communicated with the water distribution tank, the gas phase region is communicated with the steam collector, the distillation membrane and the electrode are respectively connected with the high-frequency electric signal generator through a first lead 237 and a second lead 238, so that the distillation membrane and the electrode are charged with voltage, as shown in fig. 4; the heavy metal ion-rich solution is heated by the circulating pump 21 and the first heating device 22, then passes through the heavy metal ion-rich solution inlet 234, and then enters the water distribution tank 231 of the first membrane distillation array structure 23, under the action of the water distribution tank 231, the heavy metal ion-rich solution is evenly distributed to the membrane distillation assembly 233, the heavy metal ion-rich solution is separated by the distillation membrane to obtain a gas phase (water vapor) and a liquid phase (first waste liquid), the membrane distillation assembly is separated by the distillation membrane to form a gas phase region and a liquid phase region, the first waste liquid is discharged from the first waste liquid outlet 235, passes through the second heating device 29, and then enters the second membrane distillation array structure 28 to be separated again to obtain a second waste liquid and a gas phase (water vapor); under the action of a vacuum pump, the pressure in the gas phase area is lower than 1 atmosphere, the steam pressure difference on two sides of the distillation membrane is increased, water in the solution rich in heavy metal ions is facilitated to form steam, the steam is discharged, the water producing efficiency is improved, the steam is pumped out by the vacuum pump, is discharged from a gas phase discharge port 236 and enters a steam collector, then enters a medicine adding device 123 after passing through a condensing device 26 and the vacuum pump, is prepared into leacheate again, and flows back to the spraying pool 121 for recycling; and the second waste liquid enters a crystallizer 25, the crystallizer can accelerate the crystallization speed of the second waste liquid, crystals and third waste liquid are obtained after the second waste liquid is crystallized, the crystals are recovered, and the third waste liquid is circulated to a liquid storage tank 11 rich in heavy metal ion solution for circular separation. The distillation membrane and the electrode in the membrane distillation assembly are respectively connected with a high-frequency electric signal generator, as shown in fig. 4, so that the distillation membrane and the electrode are both loaded with voltage, in the embodiment, the voltage is 5V, the frequency is 800kHz, and the high-frequency electric field can inhibit microorganisms in waste liquid from forming a biological pollution layer on the membrane surface of the distillation membrane, prevent inorganic pollution from forming crystals on the membrane surface, and reduce the performance of the membrane material.
Wherein the leacheate is NaH with the mole fraction of 1mol/L2PO4The flow rate of the solution rich in heavy metal ions is 2 cm/S;
the method for preparing the distillation membrane used in this example included,
(1) mixing 20g of multi-walled carbon nanotube and 2g of carbon nanotube alcohol dispersant in 20ml of alcohol, and ultrasonically oscillating for 30min to obtain homogenized slurry;
(2) adding 10g of polyvinylidene chloride into the homogenate, and stirring for 2 hours at the water bath condition of 50 ℃ at the stirring speed of 4r/s to obtain slurry;
(3) spraying the slurry on the surface of a polytetrafluoroethylene film by a spraying method, wherein the spraying thickness is 40 mu m; and then placing the membrane in a ventilation environment at 40 ℃ for 36h, and completely drying to obtain the distillation membrane which is a conductive hydrophobic membrane.
Example 3
The embodiment provides a device and a method for repairing heavy metal contaminated soil, the device is shown in figure 1 and comprises,
the leaching system 1 is used for leaching heavy metal contaminated soil to obtain a solution rich in heavy metal ions; as shown in fig. 2, comprises a liquid storage tank 11 rich in heavy metal ion solution, a spraying device 12, a soil storage 13, a spiral conveyor belt 14 and a leaching system shell 15; the spraying device 12 comprises a spraying tank 121, a spray head 122 and a chemical adding device 123, the leacheate is stored in the spraying tank 121, the spraying device 12 is arranged at the top of the leaching system 1, the liquid storage tank is arranged at the bottom of the leaching system, the heavy metal contaminated soil is conveyed from bottom to top by the spiral conveyor belt 14, the leacheate passes through the spray head 122 and then passes through the spiral conveyor belt from top to bottom, the heavy metal contaminated soil is leached for multiple times, the soil is leached, a solution rich in heavy metal ions is obtained, the solution is collected in the solution storage tank 11 rich in heavy metal ions, and the leached soil is conveyed to the soil storage tank 13; in this embodiment, the spiral conveyer belt is for being provided with the material of a plurality of aperture 0.8mm through-holes (the drive belt is the teflon conveyer belt), and the leacheate can pass through the through-hole and from top to bottom transmit in the drip washing system, and the number of piles sets up to 10 layers.
The membrane distillation system 2, as shown in fig. 1, includes a crystallizer 25, two membrane distillation array structures (including a first membrane distillation array structure 23 and a second membrane distillation array structure 28), a pressure control device (in this embodiment, a vacuum pump) 27, a power supply (in this embodiment, a high-frequency electrical signal generator) 24, a first heating device 22, a second heating device 29, a circulating pump 21, and a condensing device 26, wherein the crystallizer is communicated with a liquid phase outlet of the membrane distillation array structure, and a liquid outlet of the crystallizer is communicated with a liquid storage tank, and is used for performing repeated membrane distillation separation on waste liquid; the first membrane distillation array structure 23 includes a plurality of membrane distillation assemblies 233 (20 membrane distillation assemblies in this embodiment), a water distribution tank 231 and a steam collector 232, as shown in fig. 3, the water distribution tank 231 is disposed at two ends of the distillation membrane and is communicated with the liquid storage tank, and the steam collector is disposed at the bottom of the membrane distillation assemblies; a distillation membrane 2333, an electrode 2334 and a flow guide net 2331 are arranged in the membrane distillation assembly 233, the flow guide net is arranged on two sides of the distillation membrane, so that a gas phase region and a liquid phase region are formed on two sides of the distillation membrane, the liquid phase region is communicated with the water distribution tank, the gas phase region is communicated with the steam collector, the distillation membrane and the electrode are respectively connected with the high-frequency electric signal generator through a first lead 237 and a second lead 238, so that the distillation membrane and the electrode are charged with voltage, as shown in fig. 4; the heavy metal ion-rich solution is heated by the circulating pump 21 and the first heating device 22, then passes through the heavy metal ion-rich solution inlet 234, and then enters the water distribution tank 231 of the first membrane distillation array structure 23, under the action of the water distribution tank 231, the heavy metal ion-rich solution is evenly distributed to the membrane distillation assembly 233, the heavy metal ion-rich solution is separated by the distillation membrane to obtain a gas phase (water vapor) and a liquid phase (first waste liquid), the membrane distillation assembly is separated by the distillation membrane to form a gas phase region and a liquid phase region, the first waste liquid is discharged from the first waste liquid outlet 235, passes through the second heating device 29, and then enters the second membrane distillation array structure 28 to be separated again to obtain a second waste liquid and a gas phase (water vapor); under the action of a vacuum pump, the pressure in the gas phase area is lower than 1 atmosphere, the steam pressure difference on two sides of the distillation membrane is increased, water in the solution rich in heavy metal ions is facilitated to form steam, the steam is discharged, the water producing efficiency is improved, the steam is pumped out by the vacuum pump, is discharged from a gas phase discharge port 236 and enters a steam collector, then enters a medicine adding device 123 after passing through a condensing device 26 and the vacuum pump, is prepared into leacheate again, and flows back to the spraying pool 121 for recycling; and the second waste liquid enters a crystallizer 25, the crystallizer can accelerate the crystallization speed of the second waste liquid, crystals and third waste liquid are obtained after the second waste liquid is crystallized, the crystals are recovered, and the third waste liquid is circulated to a liquid storage tank 11 rich in heavy metal ion solution for circular separation. The distillation membrane and the electrode in the membrane distillation assembly are respectively connected with a high-frequency electric signal generator, as shown in fig. 4, so that the distillation membrane and the electrode are both loaded with voltage, in the embodiment, the voltage is 1.8V, the frequency is 1MHz, and the high-frequency electric field can inhibit microorganisms in the waste liquid from forming a biological pollution layer on the membrane surface of the distillation membrane, prevent inorganic pollution from forming crystals on the membrane surface, and reduce the performance of the membrane material.
Wherein the leacheate is KH with the mole fraction of 1mol/L2PO4The flow rate of the solution rich in heavy metal ions is 2 cm/S;
the method for preparing the distillation membrane used in this example included,
(1) mixing 20g of multi-walled carbon nanotube and 2g of carbon nanotube alcohol dispersant in 20ml of alcohol, and ultrasonically oscillating for 30min to obtain homogenized slurry;
(2) adding 10g of polyvinylidene chloride into the homogenate, and stirring for 2 hours at the water bath condition of 50 ℃ at the stirring speed of 5r/s to obtain slurry;
(3) spraying the slurry on the surface of a polytetrafluoroethylene film by a spraying method, wherein the spraying thickness is 12 microns; and then placing the membrane in a ventilation environment at 40 ℃ for 36h, and completely drying to obtain the distillation membrane which is a conductive hydrophobic membrane.
Test examples
The test example provides performance tests of the remediation device for heavy metal contaminated soil in examples 1-3, the test example respectively tests the content of lead and cadmium in the soil before and after leaching in examples 1-3, and the test results are shown in table 1;
table 1 performance test of the repairing apparatus for heavy metal contaminated soil in examples 1 to 3
As can be seen from Table 1, the remediation device for heavy metal contaminated soil provided by the utility model has good leaching effect and can effectively reduce the content of heavy metals in the soil;
the anti-membrane fouling capability is reflected by the condition that the water production rate is reduced, and the water production rate is reduced slowly, which shows that the anti-membrane fouling capability is good; the decline in water production rate is typically expressed using the relative water production rate (NF); the calculation method is as follows:
NF＝F0/Fn；
wherein F0The water yield per unit time (m) of the membrane distillation system when the membrane material is not polluted3/h)，FnFor the water yield per unit time (m) of the membrane distillation system after n hours of operation3H), NF is relative water yield (%).
Water yield per unit time (m)3The calculation method of/h) comprises the following steps: under the condition that other parameters are not changed, liquid backflow to the spraying tank 121 is stopped, backflow liquid is collected by other containers after the vacuum pump 27, and the volume of the backflow (namely clear water) collected within one hour is counted, so that the water yield in unit time is obtained.
As seen from the table 1, the repairing device for heavy metal contaminated soil provided by the utility model has a relative water yield of 48h when operating under the power-on condition which is obviously higher than the relative water yield of 48h when operating under the power-off condition; the electric signal is provided for the membrane distillation array structure, so that a pollution layer formed on the membrane surface by microorganisms in the waste liquid can be inhibited, inorganic pollution is prevented from forming crystals on the membrane surface, the performance of the membrane material is reduced, and the membrane distillation system has better membrane pollution resistance.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the spirit or scope of the invention.
Claims (11)
1. A device for restoring heavy metal contaminated soil is characterized by comprising,
the leaching system comprises a spiral conveyor belt arranged inside the leaching system, a spraying device arranged at the top of the leaching system and a liquid storage tank arranged at the bottom of the leaching system;
a membrane distillation system comprising, in combination,
at least one membrane distillation array structure in communication with the reservoir;
a power supply to provide an electrical signal to the membrane distillation array structure;
and the crystallizer is communicated with a liquid phase outlet of the membrane distillation array structure.
2. The remediation device of heavy metal contaminated soil according to claim 1, wherein said membrane distillation array structure comprises,
the membrane distillation components are internally provided with distillation membranes and electrodes, the distillation membranes and the electrodes are respectively connected with the power supply, and a gas phase area and a liquid phase area are respectively arranged on two sides of each distillation membrane;
the water distribution grooves are arranged at two ends of the distillation membrane, are communicated with the liquid storage tank and are simultaneously communicated with the liquid phase area;
and the steam collector is arranged at the bottom of the membrane distillation assembly and is communicated with the gas phase area.
3. The remediation device of claim 2, wherein the membrane distillation assembly further comprises a flow guide net disposed on one or both sides of the distillation membrane.
4. The remediation device of claim 2, wherein the membrane distillation system further comprises a condensing device and a pressure control device, the pressure control device being in communication with the vapor collector via the condensing device.
5. The remediation device of claim 4, wherein the spraying device comprises a doser, a spray tank and a spray head.
6. The remediation device of claim 5, wherein said pressure control means is in communication with said doser.
7. The heavy metal contaminated soil remediation device of any one of claims 1 to 6, wherein the liquid outlet of said crystallizer is in communication with said reservoir.
8. The remediation device of claim 7, wherein the membrane distillation system further comprises a circulation pump and a first heating device, and the liquid storage tank is in communication with the membrane distillation array structure through the circulation pump and the first heating device.
9. The device for remediating heavy metal contaminated soil as recited in claim 1, wherein the number of the membrane distillation array structures is two, and a second heating device is further disposed between the two membrane distillation array structures.
10. The remediation device for heavy metal contaminated soil according to claim 1, wherein the spiral conveyor belt is made of a hydrophilic material or a material provided with a plurality of through holes;
the number of layers of the spiral conveyor belt is 5-15;
the aperture of the through hole is 0.5-2.0 mm.
11. The remediation device of claim 2, wherein said distillation membrane is a conductive distillation membrane.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921781557.8U CN211275871U (en) | 2019-10-22 | 2019-10-22 | Heavy metal contaminated soil's prosthetic devices |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921781557.8U CN211275871U (en) | 2019-10-22 | 2019-10-22 | Heavy metal contaminated soil's prosthetic devices |
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| CN211275871U true CN211275871U (en) | 2020-08-18 |
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