CN104150697A - Three-level deep rapid purification device and method for heavy metals in underground water - Google Patents

Abstract

A three-stage deep and rapid purification device for heavy metals in groundwater, which removes suspended solids and colloids in groundwater through an advanced oxidation screening system, and then uses a surface repair system to build a three-stage deep purification system, using the huge root system of plants to build a first-stage absorption layer; Red mud mesoporous molecular sieves and activated carbon are used to construct a secondary enrichment layer; fly ash molecular sieves, zero-valent nano-iron, and nano-aerators are used to construct a three-stage net capture layer, and three-stage deep purification of heavy metals in groundwater is carried out. After three-stage purification , the concentration of heavy metals is close to zero, and the system has no secondary pollution, and the fixed heavy metals in the treatment process will eventually be absorbed by plants continuously. After the treatment of the present invention, the concentration and content of heavy metals in the groundwater decrease quickly and are effective for a long time.

Description

A three-stage deep rapid purification device and purification method for heavy metals in groundwater

technical field

The invention relates to a combined device for removing heavy metals in groundwater, in particular to a combined device for three-stage deep and rapid purification of heavy metals in groundwater.

The invention also relates to a method for treating heavy metals in groundwater by using the above-mentioned device.

Background technique

Nowadays, the shortage of water resources and the pollution of rivers are becoming more and more serious. The deteriorating water crisis not only exists in the pollution of rivers and lakes and other places, but also the crisis caused by groundwater pollution is becoming more and more serious. Once groundwater is polluted, it will take a lot of time and cost to purify it. Although there are laws to manage surface water, the laws and systems for managing groundwater are not perfect. As a result, fundamental solutions to pollution sources have not yet been taken. Groundwater is still being polluted. Among them, due to the serious harm of heavy metals in groundwater to the human body and the difficulty of removal, the impact of heavy metals in groundwater has become a major problem in groundwater treatment.

The commonly used method is the physical and chemical complexation of heavy metals in organic matter. The complexed heavy metals not only occupy the space position, but also easily lead to soil blockage and compaction, which has become a fatal defect in the treatment of heavy metals in groundwater. At the same time, toxic metals and salts are easy to accumulate and gel. .

Contents of the invention

The purpose of the present invention is to provide a three-stage deep rapid purification device for heavy metals in groundwater.

Another object of the present invention is to provide a method for purifying heavy metals in groundwater using the above-mentioned device.

In order to achieve the above object, the groundwater heavy metal three-stage deep rapid purification device provided by the present invention has the main structure as follows:

The groundwater lifting system is equipped with a rotatable filter screen on the inner wall of a lifting well. The filter screen plate is equipped with a needle cleaner. In the well, it is lifted to the advanced oxidation screening system;

The advanced oxidation screening system is divided into upper and lower parts by a porous plate. Above the porous plate is a sump, which is filled with mixed fillers for screening. The mixed fillers are quartz sand, modified manganese sand and natural zeolite. A mixture of molecular sieves, a nano-aeration head connected to a nano-aerator is embedded in the mixed packing; a baffle is arranged above the mixed packing, and an aeration tube is provided on the other side of the baffle, and the aeration tube is equipped with multiple Fine-hole aeration hole, the aeration hole is vertically upward, and an ultrasonic generator is installed on one side of the aeration pipe;

The water inlet side of the advanced oxidation screening system is provided with a water inlet weir, and the other side corresponding to the water inlet weir is provided with a reflux tank;

Under the perforated plate, there are closely arranged cylindrical pressure-dividing chambers to divide the space and prevent excessive local pressure from breaking through the perforated plate; below the pressure-dividing chamber is the outlet pool, the outer wall of the outlet pool is painted with light-proof black paint, and the inner wall is uniform A layer of non-metal doped photocatalyst is loaded, and an ultraviolet sterilizing lamp is installed at the bottom, and a nano aeration head connected to a nano aerator is installed between the ultraviolet sterilizing lamps, and the remaining space inside the effluent pool is filled with semiconductor loaded fillers;

One end of the water outlet pool is connected to a ventilation pipe, which is connected to the water inlet weir of the advanced oxidation screening system at the same time; the water outlet of the water outlet pool is connected to the water storage tank and the water outlet of the water storage tank through a three-way pipe, as a filter for advanced oxidation screening. The water channel for backwashing of the system;

The water outlet of the water storage tank in the advanced oxidation screening system is connected to the water distribution pipe buried under the surface absorption layer of the surface repair system through the ozone quenching device. The water distribution pipe is a perforated PVC pipe, and the pipe is wrapped with a geotextile to prevent clogging. Wrapped iron-carbon filler, with micro-electrolysis function;

The surface absorption layer is equipped with an alkaline injection device. Below the surface absorption layer are the second-level enrichment layer and the third-level net capture layer. The surface absorption layer is a mixture of soil and Flory diatomaceous earth to prevent soil loss. The surface absorption layer plants are planted above to absorb heavy metals; the secondary enrichment layer is composed of activated carbon and red mud mesoporous molecular sieve; the third-level net capture layer is filled with fly ash molecular sieve and zero-valent nano-iron; anger;

The soil compaction agent is injected around the surface repair system as an impermeable partition wall, and the bottom is a fine sand layer.

The three-stage deep and rapid purification device for groundwater heavy metals, wherein the porous plate of the advanced oxidation screening system has two layers, and a layer of stainless steel mesh is laid and fixed in the middle.

The three-stage deep and rapid purification device for heavy metals in groundwater, wherein the non-metal-doped photocatalyst uniformly loaded on the inner wall of the outlet pool is nano TiO ₂ powder.

The three-stage deep and rapid purification device for heavy metals in groundwater, wherein the semiconductor-loaded filler in the effluent pool is the filler loaded with nano- _TiO2 powder on the surface of three-dimensional network polypropylene.

The three-stage deep rapid purification device for groundwater heavy metals, wherein the volume ratio of quartz sand, modified manganese sand and natural zeolite molecular sieve in the mixed filler of the advanced oxidation screening system is 5:2:1, and the particle size is 0.5-1.2mm , with an inhomogeneity coefficient of 2, it is a multifunctional mixed filler integrating filtration, adsorption, ion exchange, coagulation and removal of heavy metals.

The three-stage deep rapid purification device for heavy metals in groundwater, wherein the mixed volume ratio of soil and Flory diatomite in the surface absorption layer is 2-3:1; activated carbon and red mud mesoporous molecular sieve in the secondary enrichment layer The volume mixing ratio is 2-3:1, the particle size of activated carbon is 5mm-20mm, and the particle size of red mud mesoporous molecular sieve is 5mm-10mm; the volume of fly ash molecular sieve and zero-valent nano-iron The ratio is 7:1, the sieve particle size of fly ash molecules is 2mm-5mm, and the particle size of zero-valent nano-iron is 2mm-5mm.

In the three-stage deep rapid purification device for heavy metals in groundwater, the aeration pipe of the advanced oxidation screening system is connected to an aerator through a flow meter.

The method for purifying groundwater heavy metal purification by utilizing upper device provided by the present invention:

Turn on the alkaline injection device to inject alkaline solution, control the pH of the surface soil layer of the surface restoration system to be slightly alkaline, and prevent the precipitation of heavy metals;

After the wastewater in the lifting well is removed by the advanced oxidation screening system to remove the suspended solid colloids in the groundwater, the residual ozone contained in the effluent is reduced by the ozone quencher, and then enters the surface restoration system through the water distribution pipe, and the huge root system of the plants in the surface absorption layer is used in turn. Absorb heavy metals, absorb and enrich the heavy metals that have not been fully absorbed by the secondary enrichment layer, under the action of red mud molecular sieve filler, absorb and neutralize the small molecular acids produced by anaerobic partial acidification, adjust the pH of sewage, and make the internal environment of the device It is more suitable for plants and microorganisms to survive, and at the same time create an alkaline environment to fix heavy metals in sewage, prevent them from leaching, use small molecular organic matter to supply plant nutrients, and absorb and absorb heavy metals in the process of plant growth for heavy metal biostabilization and secondary enrichment The heavy metals adsorbed by the layer are metabolized by the plants in the surface absorption layer, and then absorbed by the three-stage net capture layer. After the absorption-enrichment two-layer treatment, a small amount of residual heavy metals in the groundwater are kept, and the heavy metals in the three-stage net capture layer are kept at an ultra-low level. within the concentration range, and use zero-valent nano-iron to replace it, fundamentally prevent heavy metals from re-entering the groundwater; at the same time, the nano-bubbles emitted by the nano-aeration hair arranged in the three-stage net capture layer are finely dispersed in the groundwater to be treated , prevent the complexation of heavy metals and organic matter, promote the net capture effect of zero-valent iron on heavy metals, and promote the slow release of heavy metals in fly ash molecular sieves. After slow release, heavy metals are captured by zero-valent nano-iron to form colloids or microparticles , Floating under the action of nano-bubbles, the heavy metals carrying the blocking layer rise to the surface absorption layer, adhere to the Flory diatomaceous earth and be absorbed by plants.

Said method, wherein, the plants planted on the surface absorption layer of the surface restoration system are windmill grass, centipede grass, tobacco and cockscomb.

The method, wherein, the average irradiation dose of the ultraviolet germicidal lamp of the advanced oxidation screening system is above 300J/m ² .

This application removes suspended solids and colloids in groundwater through an advanced oxidation screening system. Nano-titanium dioxide crystals in the system are used as photocatalysts to excite highly oxidative free negative ions under the irradiation of ultraviolet lamps. The energy can also occur and strengthen the generation of free negative ions to achieve the photocatalytic effect; while the free negative ions and their release from the covalent bond leave vacancies, and simultaneously produce micro-electrolysis effects with the charges on the surface of the nanobubbles. Then use the surface repair system to build a three-level deep purification system, using the huge root system of plants to build a first-level absorption layer; using red mud mesoporous molecular sieves and activated carbon to build a second-level enrichment layer; and then using fly ash molecular sieves, zero-valent nano-iron, The nano-aerator builds a three-stage net capture layer, and the three-stage deep purification of heavy metals in the groundwater. After the three-stage purification, the concentration of heavy metals is close to zero. It will be continuously absorbed by plants, and after the treatment of the present invention, the concentration and content of heavy metals in groundwater will decrease quickly and be effective for a long time.

Description of drawings

Fig. 1 is a schematic diagram of a three-stage deep and rapid purification device for heavy metals in groundwater according to the present invention.

Fig. 2 is a device schematic diagram of the advanced oxidation screening system labeled 5 in Fig. 1 .

Explanation of main component symbols in the attached drawings:

1 partition wall; 2 plants; 3 alkaline injection device; 4 ozone quenching device; 5 advanced oxidation screening system; 6 water distribution pipe; 7 nanometer aeration head; 8 fine sand layer; Three-level net catch layer; 12 second-level enrichment layer; 13 surface absorption layer; 14 lifting pump; 15 needle cleaner; 16 first valve; 17 second valve; 18 booster pump; Flow plate; 21 mixed filler; 22 tee pipe; 23 aeration pipe; 24 reflux tank; 25 porous plate; 26 partial pressure chamber; 27 water storage tank; 28 third valve; Filler; 32 ultraviolet sterilization lamp; 33 outlet pool; 34 ventilation pipe; 35 ultrasonic generator; 39 nano aerator.

Detailed ways

The invention discloses a combination device for three-stage deep and rapid purification of heavy metals in groundwater, which removes suspended matter and colloids in groundwater through an advanced oxidation screening system, and then uses a surface repair system to construct a three-stage deep purification system, which is constructed by using the huge root system of plants First-level absorption layer; use red mud mesoporous molecular sieves and activated carbon to build a second-level enrichment layer; then use fly ash molecular sieves, zero-valent nano-iron, and nano-aerators to build a third-level net capture layer, and three-level deep purification of heavy metals in groundwater , after three-stage purification, the concentration of heavy metals is close to zero. At the same time, the system has no secondary pollution, and the fixed heavy metals in the treatment process will eventually be absorbed by plants continuously. Fast, and long-term effective.

Describe in detail below in conjunction with accompanying drawing. It should be noted that the left, right, up, down, etc. mentioned in the following descriptions are all based on the directions shown in the drawings.

Please refer to Fig. 1, the combined device for three-stage deep and rapid purification of heavy metals in groundwater provided by the present invention, its main structure includes three parts: groundwater lifting system, advanced oxidation screening system, and surface restoration system.

Among them, the main structure of the groundwater lifting system is a lifting well 9, and a rotatable filter screen 10 is arranged in the lifting well, and the groundwater is lifted to the original horizontal line under the suction of the lifting pump 14, and the groundwater flows through the filter during the lifting process. The net 10 is filtered so as to be processed in the next step; at the same time, in order to prevent the filter screen 10 from clogging, a needle cleaner 15 is specially provided. The effluent flows into the advanced oxidation screening system 5 .

Organic matter and heavy metals will undergo complexation, and the complexed heavy metals are only fixed, which not only occupies space, but also easily leads to soil blockage and compaction, affecting the treatment of heavy metals in groundwater, becoming a fatal defect. The advanced oxidation screening system 5 of the present invention removes most organic matter in groundwater through the principle of advanced oxidation, and shields its influence on heavy metals. The effluent treated by the advanced oxidation screening system 5 passes through the ozone quenching device 4, and the ozone quencher is used to reduce the residual ozone contained in the effluent to prevent the impact on its next step treatment.

The advanced oxidation screening system 5 of the present invention is divided into upper and lower parts by a perforated plate 25, and the perforated plate 25 is composed of a layer of stainless steel gauze sandwiched between two layers of perforated plates.

The top of the perforated plate 25 is a sump, and the middle of the sump is provided with a nano-aeration head 7 connected to a nano-aerator 39. The nano-aeration head 7 is filled with a mixed filler 21 for screening, and the mixed filler 21 is selected. The mixture of quartz sand, modified manganese sand and natural zeolite molecular sieve has a particle size of 0.5-1.2mm and a non-uniformity coefficient of 2. It is a multifunctional mixed filler integrating filtration, adsorption, ion exchange, coagulation and removal of heavy metals. A baffle 20 is arranged above the mixed filler 21, and an aeration pipe 23 is arranged on the other side corresponding to the baffle 20, and the aeration pipe 23 is provided with a plurality of fine aeration holes, and the aeration holes are vertically upward. One side of the aeration pipe 23 is equipped with an ultrasonic generator 35 . The water inlet of the advanced oxidation screening system 5 is provided with a first valve 16 , a second valve 17 and a booster pump 18 . One side of the water inlet of the advanced oxidation screening system 5 is provided with a water inlet weir 19 , and the other side corresponding to the water inlet weir 19 is provided with a backflow tank 24 .

The bottom of the perforated plate 25 is provided with closely arranged cylindrical pressure divider chambers 26 to divide the space and prevent excessive local pressure from breaking through the perforated plate 25 . Below the partial pressure chamber 26 is the water outlet pool 33, the outer wall of the water outlet pool 33 is painted with light-shielding black paint, the inner wall is uniformly loaded with a layer of non-metallic doped photocatalyst (such as nano- _TiO2 powder), and the bottom is equipped with an ultraviolet sterilizer Lamp 32, and the nanometer aeration head 7 that connects nanometer aerator is provided between the ultraviolet sterilizing lamp 32, and the remaining space inside outlet pool 33 is filled with semiconductor loading filler (such as nanometer TiO ₂ powder is loaded on three-dimensional network polypropylene on the filler). One end of the water outlet pool 33 is connected to a ventilation pipe 34, and the ventilation pipe 34 is connected to the water inlet weir 19 of the advanced oxidation screening system at the same time. The invention fixes the filler on the carrier, solves the drawbacks of conventional photocatalysts that require the coordinated use of dispersants, reduces the loss of catalysts, avoids the separation step of catalysts after the reaction, does not need to use dispersants, and reduces the loss of catalysts .

The water outlet of the water outlet pool 33 of the advanced oxidation screening system 5 is connected to the water storage tank 27 through a three-way pipe, and the three-way pipe is also connected to the water outlet of the water storage tank 27 as a water channel for backwashing the advanced oxidation screening system 5 .

During normal screening, sewage enters the advanced oxidation screening system 5 from the water inlet weir 19 . The advanced oxidation screening system 5 uses ultraviolet lamps, semiconductor-loaded fillers and nano-aeration technology to excite a large number of hydroxyl radicals to perform advanced oxidation on the effluent while filtering. The average irradiation dose of ultraviolet sterilization lamps is ^above 300J/m Among them, pollutants can kill bacteria and pathogens in sewage, and have great advantages in the treatment of environmental hormones (such as hormone pesticides, antibiotics, dioxins, estrogens, and trace harmful chemicals such as synthetic hormones). , to oxidize macromolecular refractory organic matter into low-toxic or non-toxic small molecular substances, improve the quality of effluent water, and make it meet the national reuse standard. The effluent treated by the invention has high transparency and good water quality, and at the same time, it effectively prevents the leachate from cooking waste from fermenting to produce stench, causing adverse effects on the surrounding environment, better achieves the backwashing effect, and saves water resources to the greatest extent.

Advanced Oxidation Screening System 5 The nano-aeration head in the water collection tank adopts O ₃ aeration. Due to the characteristics of large number, specific surface area, and slow rising speed of the nano-bubbles, the bubbles stay in the water for a long time, which increases the gas-liquid contact. The area and contact time are conducive to the dissolution of ozone in water, which overcomes the shortcomings of ozone insoluble in water; the microbubbles have a large internal pressure and the interface disappears when the nanobubbles break, and the chemical energy generated by the drastic changes in the surrounding environment promotes the production of more Hydroxyl radical OH enhances the ability of O ₃ to oxidize and decompose organic matter; and nano-scale O ₃ bubbles coexist with ultraviolet sterilizing lamps and semiconductor-loaded fillers in the sump to improve the advanced oxidation effect and effectively increase the OH generation rate.

The water outlet of the advanced oxidation screening system 5 is connected to the water distribution pipe 6 of the surface repair system. The water distribution pipe 6 is a perforated PVC pipe wrapped with a layer of geotextile to prevent clogging. The geotextile is wrapped with a layer of iron-carbon filler, which has micro Electrolytic function.

Soil compaction agent is injected around the surface restoration system as an impermeable partition wall 1, and a layer of fine sand 8 is compacted at the bottom. The interior of the surface restoration system consists of a surface absorption layer 13, a secondary enrichment layer 12, and a tertiary net capture layer 11 from top to bottom. The layers are separated by grids with a mesh diameter of 1mm to prevent each The layers of packing flow between each other. The surface absorption layer 13 is filled with 0.3m of soil and Flory diatomaceous earth, and the volume mixing ratio is 2-3:1 to prevent soil loss. At the same time, an alkaline injection device 3 is provided to control the pH value of the constructed wetland and prevent Heavy metals are precipitated, and plants 2 are planted to absorb heavy metals; the secondary enrichment layer 12 is 0.6m thick, and is composed of activated carbon with a particle size of 5mm-20mm and red mud mesoporous molecular sieves with a particle size of 5mm-10mm. The volume of activated carbon and red mud mesoporous molecular sieves The mixing ratio is 2-3:1, which is used to adsorb and enrich the heavy metals that cannot be fully absorbed. The heavy metals stored in the secondary enrichment layer 12 are absorbed through the metabolic process of the plant in the surface absorption layer 13; The thickness is 0.4m, and the interior is filled with fly ash molecular sieve with a particle size of 2mm-5mm and zero-valent nano-iron of 2mm-5mm. The fly ash molecular sieve instantly absorbs a small amount of residual heavy metals in the groundwater after two layers of absorption-enrichment treatment, and makes the three The heavy metals in the first-level net capture layer are kept in an ultra-low concentration range, and at the same time, zero-valent nano-iron is used to replace them, which fundamentally prevents the possibility of heavy metals re-entering the groundwater. The nano-bubbles emitted by the gas head have special properties. Under physical action, they are finely dispersed in the groundwater to be treated, which can prevent the complexation of heavy metals and organic matter, promote the net capture of zero-valent iron on heavy metals, and promote the recovery of pulverized coal. The slow release of heavy metals in ash molecular sieves, the heavy metals after slow release are captured by zero-valent nano-iron, forming colloid or micro-particle precipitation, floating up under the action of nano-bubbles, and the heavy metals carrying the blocking layer rise to the surface absorption layer and adhere to the surface Rory diatomaceous earth is absorbed by plants;

Planting plants on the surface absorption layer of the surface remediation system 2 Select windmill grass, centipede grass, tobacco, cockscomb, etc., and adjust the planting ratio to the heavy metals to be absorbed to ensure the best absorption effect and have a landscape effect.

The three-stage net capture layer of the surface remediation system and the nano-aeration head in the screening tank and storage tank of the advanced oxidation screening system are respectively connected with a nano-aerator.

According to an embodiment of the present invention, the removal rate of heavy metals is as high as 100%, the content of trace organic matter is reduced by more than 95%, and the characteristic fluorescence peak of proteinoid substances is reduced by more than 90%.

The advanced oxidation screening system of the present invention adopts three-stage backwashing technology for backwashing.

The first-level backwash is an aeration cycle backwash. Due to the accumulation of pollutants on the surface of the packing, it is difficult for the sewage to penetrate through the gaps between the packing. The pressure pump 18, the aeration pipe 23 and the nano-aeration head 7 above the porous plate are intermittently opened, the nano-aeration head in the sump works discontinuously, the air bulges upward from the porous plate, is divided into small bubbles, and the sieve packing is intermittently washed away The dense dirt layer on the top, the pollutant layer is broken into flakes and floats, and the wave wheel effect is produced under the synergistic effect of the buoyancy of the aeration tube and the rightward thrust of the water impact baffle, and the flaky dense pollution on the surface of the packing is vigorously cleaned. The pollutants overflow to the backflow tank, so that the pollutants retained by the packing are excluded from the device, mixed with the influent water for retreatment, and the sewage can continue to permeate from the molecular sieve gap; the first-level backwash can prolong the service life of the screening device and backwash Period, for the case of low influent turbidity, even backwashing is not required, so that the device can continue to operate to purify sewage.

The second-stage backwash is an air pulse backwash. Due to the high turbidity of the sewage, a large amount of pollutants accumulate on the surface of the filler. The effect of continuous screening cannot be achieved only by the first-stage backwash step. Close the first valve 16 and the fourth valve 29, open the third valve 28 and the second valve 17, start the water pump 30, the aeration pipe 23 and the two nano aerator heads 9 of the advanced oxidation screening system 5, and the water outlet tank The outlet water in 33 imports in the sump. Under the action of the return water pressure, all the air in the sump is squeezed rapidly and rises along the fine holes on the partial pressure chamber 26. All the 21 layers of mixed filler are vigorously stirred by the rising air, and the air flow of the aeration tube 23 and nano-aeration Under the action of the impact force of the head, the pollutants are broken and floated, and under the synergistic effect of the buoyancy of the aeration tube 23 and the rightward thrust of the incoming water impact baffle, they overflow to the backflow tank 24 and mix with the initial incoming water. After the water level drops rapidly and the filtration rate is stabilized again, close the water pump 30 of the advanced oxidation screening system 5, the nano-aeration head 7, the third valve 28 and the second valve 17 under the porous plate, and open the first valve 16 and the fourth valve 29 Proceed to the sieving process.

The third-stage backwashing is aeration turbulent backwashing. At this time, the first and second-stage backwashing are not enough to solve the problem of covering and blocking the filler by pollutants, and a large amount of sewage cannot be filtered. Now close the first valve 16 and the fourth valve 29, open the third valve 28 and the second valve 17, start the water pump 30, the aeration pipe 23 and two nanometer aeration heads 7 of the advanced oxidation screening system 5, and the ultrasonic generation Instrument 43, a large amount of effluent in the effluent pool is imported in the sump. ⑴The air inside the sump rises and stirs along the pores of the porous plate, the nano-aeration head at the bottom of the mixed filler 21 starts to aerate, and the turbine above the mixed filler 21 rotates continuously; , the upper packing presents a state of turbulent flow and is in a state of irregular high-speed motion. The mixed packing 21 rubs against each other under the impact force of the vortex of the water flow and the shear force of the air bubbles, and the organic pollutants attached to the mixed packing 21 can be removed to obtain relatively pure Filling; (3) Ultrasonic waves are generated in the liquid medium by an ultrasonic generator, and a cavitation effect is generated on the surface of the mixed filler 21. The shock wave formed when the cavitation bubble breaks during the closing process will generate a shock pressure of thousands of air pressures around it. , acts on the surface of the mixed filler 21 to break the stickiness between the dirt and make them quickly disperse in the backwash liquid, thereby achieving the effect of cleaning the filler surface. (4) After the air is exhausted, the effluent from the effluent pool continues to be introduced, and the effluent rich in hydroxyl radicals washes the particle surface and micropores of the turbulent mixed filler 21, strips off pollutants, and regenerates the mixed filler 21. (5) The pollutants float upwards to the water surface continuously under the impact force of the water flow and the air flotation effect of the right aeration pipe 23, and flow out from the left end water inlet weir 19 and the right end reflux groove 24 to mix with the initial water inlet. After three-stage backwashing, the internal pollutants are cleaned and emptied. The aeration pipe of the advanced oxidation screening system is connected with an aerator through a flow meter.

_The air intake of the nano-aeration head of the advanced oxidation screening system is O ₂ for backwashing, which is used for coagulation and stirring and cleaning of the filler; Strengthens the production process of hydroxyl radicals.

Conventional sand filtration does not disturb the sand layer during the filtration process, allowing water to flow through the small gaps in the sand. Usually, the sand filtration process is improved by means of not disturbing the sand layer, compacting the filler, increasing the water pressure, and adding grids on the sand, so that the water flows through the small gaps in the sand, while the pollutants stay on the surface of the sand layer. The present invention utilizes the surface layer of disturbing filler to prevent the accumulation of pollutants from forming resistance to the smooth passage of water flow, and at the same time utilizes advanced oxidation, nano-aeration, impact force and shear force of air bubbles to improve the device, and uses fillers such as molecular sieve and manganese sand Optimize the design, and finally use three-stage backwashing to improve the treatment process. The present invention has good interception effect on colloid, fiber, algae and other suspended matter, and can complete the treatment process for water with low turbidity even without backwashing. At the same time, it has the functions of removing odor, killing microorganisms such as bacteria and pathogenic bacteria, and is difficult to degrade when decomposed. The efficacy of a small amount of residual surfactants, polychlorinated biphenyls and other refractory organic compounds.

Carbon-doped nano _TiO of the present invention Preparation of powder:

Carbon-doped nano-TiO ₂ was prepared by a two-step process of uniform precipitation and hydrothermal method. With titanium sulfate and urea as the precursor, glucose as the carbon source, the specific preparation process is as follows: take 6.48g27 titanium sulfate and 3.24g54 urea (the molar ratio of titanium sulfate and urea is 1:2) dissolved in deionized water, and then add an appropriate amount of Glucose 0.6 was stirred evenly, and reacted at 90°C for 2 hours. After the reaction is finished, the reactant is taken out and dried, repeatedly washed with water until neutral, dried again, and ground with a ball mill to obtain carbon-doped nano TiO ₂ powder.

The method of loading nano TiO ₂ powder on the filler:

The three-dimensional network structure filler made of polypropylene is used to mix nano-TiO ₂ powder with deionized water (the mass ratio of powder and water is 1:20), and the emulsion is formed by ultrasonic wave, and the clean three-dimensional network The structural filler is immersed in the titanate coupling agent mixed with ethanol in a volume ratio of 1:1, stirred slowly for a period of time, then the filler is taken out and placed in the _TiO2 emulsion to continue stirring for a period of time, and then placed in an oven to dry ( Below 85°C) for 2 hours, the polypropylene suspension filler loaded with nano-TiO ₂ is prepared, the appearance is light yellow, and the film layer is relatively uniform.

Claims (10)

1. A three-stage deep rapid purification device for heavy metals in groundwater, the main structure of which is: The groundwater lifting system is to install a rotatable filter screen on the inner wall of a lifting well. The filter screen is equipped with a needle cleaner. Upgrade to advanced oxidation screening system; The advanced oxidation screening system is divided into upper and lower parts by a porous plate. Above the porous plate is a sump, which is filled with mixed fillers for screening. The mixed fillers are quartz sand, modified manganese sand and natural zeolite. A mixture of molecular sieves, a nano-aeration head connected to a nano-aerator is embedded in the mixed packing; a baffle is arranged above the mixed packing, and an aeration tube is provided on the other side of the baffle, and the aeration tube is equipped with multiple Fine-hole aeration hole, the aeration hole is vertically upward, and an ultrasonic generator is installed on one side of the aeration pipe; The water inlet side of the advanced oxidation screening system is provided with a water inlet weir, and the other side corresponding to the water inlet weir is provided with a reflux tank; Under the perforated plate, there are closely arranged cylindrical pressure-dividing chambers to divide the space and prevent excessive local pressure from breaking through the perforated plate; below the pressure-dividing chamber is the outlet pool, the outer wall of the outlet pool is painted with light-proof black paint, and the inner wall is uniform A layer of non-metal doped photocatalyst is loaded, and an ultraviolet sterilizing lamp is installed at the bottom, and a nano aeration head connected to a nano aerator is installed between the ultraviolet sterilizing lamps, and the remaining space inside the effluent pool is filled with semiconductor loaded fillers; One end of the water outlet pool is connected to a ventilation pipe, which is connected to the water inlet weir of the advanced oxidation screening system at the same time; the water outlet of the water outlet pool is connected to the water storage tank and the water outlet of the water storage tank through a three-way pipe, as a filter for advanced oxidation screening. The water channel for backwashing of the system; The water outlet of the water storage tank in the advanced oxidation screening system is connected to the water distribution pipe buried under the surface absorption layer of the surface repair system through the ozone quenching device. The water distribution pipe is a perforated PVC pipe, and the pipe is wrapped with a geotextile to prevent clogging. Wrapped iron-carbon filler, with micro-electrolysis function; The surface absorption layer is equipped with an alkaline injection device. Below the surface absorption layer are the second-level enrichment layer and the third-level net capture layer. The surface absorption layer is a mixture of soil and Flory diatomaceous earth to prevent soil loss. The surface absorption layer plants are planted above to absorb heavy metals; the secondary enrichment layer is composed of activated carbon and red mud mesoporous molecular sieve; the third-level net capture layer is filled with fly ash molecular sieve and zero-valent nano-iron; anger; The soil compaction agent is injected around the surface repair system as an impermeable partition wall, and the bottom is a fine sand layer. 2. The groundwater heavy metal three-stage deep rapid purification device according to claim 1, wherein the porous plate of the advanced oxidation screening system has two layers, and a layer of stainless steel mesh is laid and fixed in the middle. 3. The groundwater heavy metal three-stage deep rapid purification device according to claim 1, wherein the non-metallic doped photocatalyst uniformly loaded on the inner wall of the outlet pool is nano TiO ₂ powder. 4. The three-stage deep rapid purification device for groundwater heavy metals according to claim 1, wherein the semiconductor-loaded filler in the effluent pool is nano TiO ₂ powder loaded on the surface of three-dimensional network polypropylene. 5. The groundwater heavy metal three-level deep rapid purification device according to claim 1, wherein the volume ratio of quartz sand, modified manganese sand and natural zeolite molecular sieve in the mixed filler of advanced oxidation screening system is 5:2:1, and the particle The diameter is 0.5-1.2mm, and the non-uniformity coefficient is 2. It is a multifunctional mixed filler integrating filtration, adsorption, ion exchange, coagulation and removal of heavy metals. 6. groundwater heavy metal three-level depth fast purification device according to claim 1, wherein, the mixing volume ratio of soil and Flory diatomite in the surface absorption layer is 2-3:1; In the secondary enrichment layer, activated carbon The volume mixing ratio with red mud mesoporous molecular sieve is 2-3:1, the particle size of activated carbon is 5mm-20mm, and the particle size of red mud mesoporous molecular sieve is 5mm-10mm; the fly ash molecular sieve and The volume ratio of zero-valent nano-iron is 7:1, the sieve particle size of fly ash molecules is 2mm-5mm, and the particle size of zero-valent nano-iron is 2mm-5mm. 7. The groundwater heavy metal three-stage deep rapid purification device according to claim 1, wherein the aeration pipe of the advanced oxidation screening system is connected with an aerator through a flow meter. 8. Utilize the method for purifying by the groundwater heavy metal three-stage deep rapid purification device described in claim 1: Turn on the alkaline injection device to inject alkaline solution, control the pH of the surface soil layer of the surface restoration system to be slightly alkaline, and prevent the precipitation of heavy metals; After the wastewater in the lifting well is removed by the advanced oxidation screening system to remove the suspended solid colloids in the groundwater, the residual ozone contained in the effluent is reduced by the ozone quencher, and then enters the surface restoration system through the water distribution pipe, and the huge root system of the plants in the surface absorption layer is used in turn. Absorb heavy metals, absorb and enrich the heavy metals that have not been fully absorbed by the secondary enrichment layer, under the action of red mud molecular sieve filler, absorb and neutralize the small molecular acids produced by anaerobic partial acidification, adjust the pH of sewage, and make the internal environment of the device It is more suitable for plants and microorganisms to survive, and at the same time create an alkaline environment to fix heavy metals in sewage, prevent them from leaching, use small molecular organic matter to supply plant nutrients, and absorb and absorb heavy metals in the process of plant growth for heavy metal biostabilization and secondary enrichment The heavy metals adsorbed by the layer are metabolized by the plants in the surface absorption layer, and then absorbed by the three-stage net capture layer. After the absorption-enrichment two-layer treatment, a small amount of residual heavy metals in the groundwater are kept, and the heavy metals in the three-stage net capture layer are kept at an ultra-low level. within the concentration range, and use zero-valent nano-iron to replace it and catch it with a net, fundamentally prevent heavy metals from re-entering the groundwater; at the same time, the nano-bubbles emitted by the nano-aeration hair arranged in the third-level net capture layer are finely scattered in the water to be treated prevent the complexation of heavy metals and organic matter, promote the net capture effect of zero-valent iron on heavy metals, and promote the slow release of heavy metals in fly ash molecular sieves. After slow release, heavy metals are captured by zero-valent nano-iron to form colloids or The microparticles settle and float up under the action of nanobubbles, and the heavy metals carrying the blocking layer rise to the surface absorption layer and adhere to the Flory diatomaceous earth to be absorbed by plants. 9. The method according to claim 8, wherein the plants planted on the surface absorption layer of the ground surface restoration system are windmill grass, centipede grass, tobacco and cockscomb. 10. The method according to claim 8, wherein the average irradiation dose of the ultraviolet sterilization lamp of the advanced oxidation screening system is above 300J/m ² .