A three-dimensional electrochemical enhanced multilayer soil infiltration system

Abstract

This invention belongs to the field of wastewater treatment technology and discloses a three-dimensional electrochemically enhanced multilayer soil infiltration system. It includes a main body with pebble cushion layers at the top and bottom. A filler zone is located between the top and bottom pebble cushion layers, where clean water layers and water-passing layers are alternately arranged. A first clean water layer is placed on the bottom pebble cushion layer, and these layers are arranged alternately. Graphite electrode plates are alternately arranged inside the main body and connected to a DC power supply. The graphite electrode plate connected to the positive terminal of the DC power supply is the anode, and the graphite electrode plate connected to the negative terminal is the cathode. The water-passing layer is composed of a mixture of zeolite, ceramsite, and granular activated carbon, with the granular activated carbon acting as particle electrodes, thus constructing a three-dimensional electrochemically enhanced multilayer infiltration system. This electrochemically enhanced multilayer soil infiltration system achieves removal rates of 93.42%, 87.33%, 98.52%, and 78.73% for COD, TN, NH3-N, and TP in domestic wastewater, respectively.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a three-dimensional electrochemical enhanced multilayer soil infiltration system. Background Technology

[0002] Currently, there are physical, biological, and ecological treatment technologies for the treatment of decentralized domestic sewage in rural areas. Among them, ecological treatment technologies do not require large-scale civil engineering and do not require the addition of chemical reagents, offering advantages such as low cost and no secondary pollution. These technologies mainly include ecological oxidation ponds, constructed wetlands, and soil infiltration systems. However, ecological oxidation ponds and constructed wetlands have drawbacks such as large land area requirements and sensitivity to environmental changes, making them unsuitable for widespread application. Soil infiltration systems (SIS) are a relatively new and cost-effective sewage treatment technology. A traditional SIS consists of a distribution layer (upper layer), typically composed of permeable soil, followed by a treatment layer (the core of the SIS), with a specially designed soil structure and permeability. The bottom layer is the effluent layer, i.e., the drainage pipes. It involves controlled distribution of sewage into the highly permeable soil. During the downward infiltration process, the sewage is purified through a series of physical, chemical, and biological processes, including filtration, sedimentation, oxidation-reduction, and biological metabolism. However, traditional soil infiltration systems suffer from drawbacks such as simple structure, poor nitrogen removal efficiency, and low treatment load, which limit their practical application. CN217398693U provides a soil infiltration ecological cycle system by connecting soil infiltration systems, ecological ditches, and farmland, but it has disadvantages such as large land area, need to be carried out in specific locations, and insufficient nitrification-denitrification capacity.

[0003] Therefore, it is necessary to develop a soil infiltration system that has a small footprint and high operating efficiency. Summary of the Invention

[0004] To address the shortcomings and deficiencies of existing technologies, the purpose of this invention is to propose a three-dimensional electrochemically enhanced multilayer soil infiltration system.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A three-dimensional electrochemical enhanced multilayer soil infiltration system includes a main body (5), with a pebble cushion layer (4) at the top and bottom of the main body (5). The top pebble cushion layer and the bottom pebble cushion layer are in a filling zone. An anaerobic water purification layer (1) and an aerobic water permeable layer (2) are alternately arranged in the filling zone. A first water purification layer is set on the bottom pebble cushion layer and connected to the water purification layer. A first water permeable layer is filled in the upper part and around the first water purification layer, and the layers are alternately arranged in sequence.

[0007] Inside the main body (5), graphite electrode plates are arranged alternately. The graphite electrode plates are connected to a DC power supply. The graphite electrode plate connected to the positive terminal of the DC power supply is the anode, and the graphite electrode plate connected to the negative terminal of the DC power supply is the cathode. The first graphite electrode plate is set on the first water purification layer. The graphite electrode plates are arranged alternately at equal intervals in sequence. Through the synergistic effect of electrochemistry and microorganisms, the denitrification and phosphorus removal effect of the system is enhanced.

[0008] The water-passing layer (2) is composed of zeolite, ceramsite, and granular activated carbon. The granular activated carbon is located between the anode and cathode two-dimensional electrodes, forming a three-dimensional particle electrode.

[0009] Preferably, the length, width and height of the main body (5) are 25cm×25cm×40cm.

[0010] Preferably, the pebble pad (4) is 5cm thick and the pebble size is 15-25mm. Laying a 5cm pebble pad at both the top and bottom of the system allows the treated wastewater to flow smoothly under gravity and ensures that the water-passing layer material is laid flat, preventing leakage to the pebble pad and clogging of the outlet.

[0011] Preferably, the height of the internal filling area is 30cm, and the clean water layer (1) and the water flow layer (2) are arranged alternately at a height of 5cm.

[0012] Preferably, the water-passing layer is composed of zeolite with a particle size of 3-5 mm, ceramsite with a particle size of 5-8 mm, and granular activated carbon with a particle size of 4-8 mm in a dry weight ratio of 1:1:1.

[0013] Preferably, the water purification layer is made by mixing red soil, biochar, iron-carbon pellets and rice husks with water in a dry weight ratio of 7:1:1:1, wrapping the mixture in jute cloth and air-drying it to obtain square brick-shaped soil blocks with a length, width and height of 20cm×10cm×5cm. The system has a total of three water purification layers, with two square brick-shaped soil blocks laid in each layer.

[0014] Preferably, the graphite electrode plate has a length, width, and thickness of 20cm×20cm×30mm, and 16 water passage holes with a diameter of 5mm are provided on the plate. Four graphite plates are placed alternately at a height of 4-5cm, more specifically 4.4cm.

[0015] Preferably, the graphite electrode plate is connected to the power supply via a copper wire, and waterproof adhesive is applied to the connection between the graphite electrode plate and the copper wire to prevent corrosion of the copper wire.

[0016] Preferably, the lower part of the main body (5) is provided with a water outlet hole with a diameter of 2-3cm, and the water outlet hole is connected to a PVC water pipe for drainage.

[0017] Preferably, the material of the main body (5) is plexiglass.

[0018] A three-dimensional electrochemical enhanced multilayer soil infiltration system is based on traditional soil infiltration treatment systems. It modularizes the soil into soil mixing modules, which are alternately distributed as clean water layers (SMBs) and flow layers (PLs). Multiple aerobic and anaerobic zones are established, utilizing physical filtration, chemical adsorption and exchange, and biological decomposition. Graphite plates form the anode and cathode within the system, while granular activated carbon is added between the anode and cathode plates to act as three-dimensional particle electrodes. This constructs a three-dimensional electrochemical enhanced multilayer infiltration system, achieving an ecological water purification technology system for removing pollutants, especially organic matter and nitrogen and phosphorus. It boasts advantages such as low operating costs, resistance to clogging, comprehensive water purification functions, and excellent results.

[0019] The operating principle of the three-dimensional electrochemical enhanced multilayer soil infiltration system is as follows: After domestic sewage is introduced into the system using a peristaltic pump, the organic matter in the wastewater is first adsorbed on the outer surface of the soil and large particle packing material, and further decomposed by the system's microorganisms. Simultaneously, the sewage flows vertically from top to bottom, passing through the cathode and anode layers before exiting through the bottom outlet. This electrochemical system further enhances the sewage treatment effect. The nitrogen in the wastewater mainly consists of organic nitrogen and ammonia nitrogen. When the wastewater flows through the PLs, the added zeolite and ceramsite have a large specific surface area, resulting in a strong adsorption capacity for NH3-N. Under aerobic conditions, nitrifying bacteria oxidize NH3-N into NO2-N and NO3-N. NO3-N is then transferred to the anaerobic SMBs, where denitrifying bacteria reduce it to N2, NO, and N2O before discharging it from the system. During the energization process, a hydrolysis reaction occurs on the anode plate, generating hydroxyl radicals that oxidize NH3-N. The iron-carbon microspheres oxidize and precipitate Fe on the anode plate. 2+ It can be used as an inorganic electron source for NO3. - -N denitrification provides electrons, promoting NO3- - -N autotrophic denitrification, with oxidation occurring in the anolyte to produce H₂ + Hydrogen ions are reduced to hydrogen gas (NO3) in the cathode layer. - -N is reduced to N2 at the cathode via autotrophic denitrification of hydrogen, thus achieving NO3. - -N removal; simultaneously, granular activated carbon serves as an additional carbon source for NO3. - The denitrification of -N provides more electrons, thus promoting NO3- - Removal of -N.

[0020] However, due to the Fe generated by anodic electrolysis during system energization... 2+The granular activated carbon competes with nitrifying bacteria for oxygen, inhibiting their growth. This leads to an increased carbon source concentration within the system, reducing the oxygen content during nitrification. Furthermore, the hydrogen generated during cathode reduction creates an oxygen-deficient environment around the cathode, further inhibiting nitrification. Consequently, the EC-AC-MSL system becomes less effective at controlling NH4+. + The removal efficiency of -N is comparable to that of ordinary MSL. Meanwhile, the biochar and rice husks added to SMBs can serve as external carbon sources to further promote denitrification within the system.

[0021] For the removal of phosphorus (P) from wastewater, the removal of phosphorus (Fe) from the system is achieved through the removal of phosphorus (Fe). 3+ Fe(OH)3 is removed by adding typical red soil from South China, rich in iron, to SMBs. The EC-AC-MSL system, under electrochemical enhancement, accelerates the ionization of Fe at the anode. 3+ Further promote Fe 3+ It flocculates and precipitates phosphates, thereby improving the phosphorus removal effect of the system; at the same time, granular activated carbon can effectively improve the electron transport performance within the system, allowing Fe to... 2+ Further oxidation to Fe 3+ Secondly, iron-carbon microspheres were added, utilizing the Fe produced by the iron-carbon micro-electrolysis. 2+ Entering PLs, it is oxidized to Fe. 3+ With PO4 in wastewater 3- Precipitation forms, and Fe in the system 3+ It mainly exists as hydroxides, and PO4 in wastewater 3- It can combine with these hydroxides to achieve the effect of phosphorus removal.

[0022] The present invention has the following advantages and beneficial effects:

[0023] 1. Figure 1-5 This study compares the concentrations of ammonia nitrogen (NH3-N), nitrite nitrogen, nitrate nitrogen, total phosphorus (TP), and COD in the effluent of the MSL system with those of a conventional MSL system. The system achieves removal rates of 93.42%, 87.33%, 98.52%, and 78.73% for COD, TN, NH3-N, and TP in domestic wastewater, respectively. The effluent COD concentration meets the Class I standard (COD ≤ 15 mg / L) of the Surface Water Environmental Quality Standard (GB 3838-2002); the effluent NH3-N concentration meets the Class I standard (NH3-N ≤ 0.15 mg / L); and the effluent TP concentration basically meets the Class IV standard (TP ≤ 0.3 mg / L).

[0024] 2. The alternating arrangement of the clean water layer and the circulating water layer creates aerobic and anaerobic zones, which enhances the system's nitrification-denitrification capacity and improves the system's nitrogen and phosphorus removal efficiency for domestic sewage.

[0025] 3. By adding iron-carbon microspheres to the water purification layer, a galvanic cell is formed using the principle of metal corrosion, which not only provides a carbon source to the system but also enhances the system's phosphorus removal effect.

[0026] 4. Alternating graphite plates are placed within the system to form electrochemical anodes and cathodes. An external DC power supply is used to form an electrochemically enhanced multilayer percolation system, which improves the system's nitrogen and phosphorus removal efficiency.

[0027] 5. Granular activated carbon was added as particle electrodes to the cathode and anode plates inside the system to construct a three-dimensional electrochemical enhanced multilayer percolation system, which further enhances the system's nitrogen and phosphorus removal functions.

[0028] 6. All packing materials used in this system can be purchased online at low prices, resulting in low overall system construction costs and a small footprint, making it suitable for use in rural areas. Attached Figure Description

[0029] Figure 1 The dynamic changes of ammonia nitrogen in a conventional MSL system and the EC-AC-MSL multilayer soil infiltration system of this invention are shown.

[0030] Figure 2 The dynamic changes of nitrite nitrogen in a conventional MSL system and the EC-AC-MSL multilayer soil infiltration system of this invention are shown.

[0031] Figure 3 The dynamic changes of nitrate nitrogen in a conventional MSL system and the EC-AC-MSL multilayer soil infiltration system of this invention are shown.

[0032] Figure 4 The dynamic changes of total phosphorus in the conventional MSL system and the EC-AC-MSL multilayer soil infiltration system of this invention are shown.

[0033] Figure 5 The dynamic changes of COD in a conventional MSL system and the EC-AC-MSL multilayer soil infiltration system of this invention are shown.

[0034] Figure 6 This is a schematic diagram of the multi-layer soil infiltration system device of the present invention. 1 is the water purification layer (SMBs), 2 is the water circulation layer (PLs), 3 is the graphite electrode plate, 4 is the pebble cushion layer, and 5 is the acrylic plexiglass body.

[0035] Figure 7 To invent a graphite electrode plate for use in a multi-layer soil infiltration system. Detailed Implementation

[0036] The present invention will be further described below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. For process parameters not specifically noted, conventional techniques can be referred to.

[0037] The iron-carbon spheres were purchased from Pingdingshan Lvzhiyuan Activated Carbon Co., Ltd.

[0038] The biochar was purchased from Gongyi Shengxiang Activated Carbon Business Department.

[0039] The red soil was taken from typical red soil in South China.

[0040] The rice husks were purchased from the Fuyuan City Branch of China Post Group Corporation in Heilongjiang Province.

[0041] Example 1

[0042] Figure 6 The three-dimensional electrochemical enhanced multilayer percolation system for simultaneous nitrogen and phosphorus removal of this invention uses an acrylic cube measuring 25cm × 25cm × 40cm. A 2cm diameter outlet hole is located at the bottom of the device, connected to a PVC water pipe for drainage and sampling. Each device has a 5cm layer of pebbles (approximately 15-25mm in diameter) at both the top and bottom. This layer allows the treated wastewater to flow smoothly under gravity and ensures the flatness of the permeable layer (PLs) material, preventing leakage and clogging of the outlet. Above the bottom pebbles is a 5cm high clean water layer (SMBs), consisting of two square brick-shaped soil blocks measuring 20cm × 10cm × 5cm, spaced 5cm apart. A water-permeable layer consisting of zeolite (particle size approximately 3–5 mm), ceramsite (particle size approximately 4–8 cm), and granular activated carbon (particle size approximately 4–8 mm) in a dry weight ratio of 1:1:1 is laid around and above the SMBs. Figure 6The entire system is filled with alternating PLs and SMBs. The purified water layer is a mixture of four fillers: lateritic red soil, biochar, iron-carbon microspheres, and rice husks, in a dry weight ratio of 7:1:1:1. There are three layers of purified water, each containing two pieces, with a total of six filler pieces in a 20:10:5 ratio. The device's interior consists of alternating water-passing and purified water layers. Inside the device, four graphite electrode plates (20cm×20cm×30mm) are placed alternately at 4-5cm intervals to form the anode and cathode. The water-passing and purified water layers are alternately filled between the two electrode plates. Sixteen 5mm diameter water passages are set on the electrode plates to prevent clogging. The electrode plates are connected to a DC power supply via copper wires, and waterproof adhesive is applied at the junction of the copper wires and electrode plates to prevent corrosion. A 5cm pebble layer is laid at both the top and bottom. The bottom layer is connected to the clean water layer. A 5cm water permeable layer is filled between the two clean water layers. Then, another clean water layer is laid on top, followed by another 5cm water permeable layer. Finally, a 5cm water permeable layer is laid and the pebble layer is used to seal the top.

[0043] In this embodiment, the multi-layer soil infiltration system provided by the present invention is used to treat rural domestic sewage. The influent quality is approximately 10 mg / L ammonia nitrogen, approximately 0.001 mg / L nitrite nitrogen, approximately 3 mg / L nitrate nitrogen, approximately 1.5 mg / L total phosphorus, and approximately 100 mg / L COD.

[0044] Before the device is put into formal operation, it uses domestic sewage to naturally form a biofilm in the system through a saturated continuous flow influent method. The operation time is one week. The nitrogen and phosphorus content of the system effluent is measured to determine whether the packing material in the system has formed a biofilm.

[0045] Domestic sewage enters the system from the top via a peristaltic pump. It first passes through a large-particle packing layer (water-passing layer) where COD is adsorbed and degraded. Following natural biofilm formation, nitrifying bacteria attach to the water-passing layer due to its aerobic nature. These bacteria remove NH3-N from the sewage through nitrification, reducing NO3-. - and NO3 in wastewater - By entering the soil module (clean water layer), denitrifying bacteria attach to the anaerobic environment. These bacteria then carry out denitrification under anaerobic conditions, removing NO3 from the wastewater. - The nitrogen is converted into N2 for removal, and as the wastewater flows from top to bottom, it undergoes repeated alternating nitrification-denitrification processes, which efficiently removes nitrogen from the wastewater.

[0046] The phosphorus (P) in the wastewater is converted into Fe through micro-electrolysis of iron-carbon microspheres in the purification layer. 2+ Upon entering the aquifer, it is oxidized to Fe under aerobic conditions. 3+ With PO4 in wastewater3- The resulting precipitate settles at the bottom of the system, removing phosphorus (P) from the wastewater.

[0047] Electrochemistry utilizes the stimulation of microcurrents to clean and regenerate the biofilm on the surface of the packing material, restoring the performance of the biofilm and improving the removal of COD, N, and P from wastewater, as well as the diversity and richness of microorganisms in the system.

[0048] During operation, effluent is discharged via a peristaltic pump with a hydraulic retention time of 12 hours. The process follows the sequence of influent → electrolysis → effluent discharge. The system current intensity is set at 10 mA, and the electrolysis time is 4 hours. The device operates continuously for one month, and the effluent concentration conforms to the Class V water quality standard of the Surface Water Environmental Quality Standard.

[0049] Comparative Example 1

[0050] In the MSL system of the present invention, the water-passing layer is composed of ceramsite and zeolite in a dry weight ratio of 1:1, while in the EC-AC-MSL system, the water-passing layer is composed of ceramsite, zeolite and activated carbon in a dry weight ratio of 1:1:1, and the MSL system does not have graphite electrode plates.

[0051] Test case

[0052] (1) Determination of ammonia nitrogen content in the effluent of the EC-AC-MSL system and the MSL system:

[0053] Take appropriate amounts of pretreated water sample (ammonia nitrogen content not exceeding 0.1 mg) and ammonia-free water (as a blank), add them to a 50 ml colorimetric tube, dilute to the mark, add 1.0 ml of potassium sodium tartrate, and mix well. Add 1.5 ml of Nessler's reagent and mix well. After standing for 10 minutes, measure the absorbance at a wavelength of 420 nm using a 20 mm path length cuvette, with water as a reference (zeroed).

[0054] The results are as follows Figure 1 As shown, compared with the effluent treated by the MSL system alone, the effluent treated by the EC-AC-MSL system undergoes nitrification, and the ammonia nitrogen content in the EC-AC-MSL effluent is 0.15 mg / L, which is a significant reduction. The EC-AC-MSL system has a 98.52% removal rate of ammonia nitrogen from domestic sewage.

[0055] (2) Determination of nitrite nitrogen content in the effluent of the EC-AC-MSL system and the MSL system:

[0056] Take a portion of the pretreated water sample into a 50 mL colorimetric tube (if the concentration is high, take an appropriate amount and dilute it with water to the mark), add 1.0 mL of colorimetric reagent, and then follow the same steps as the calibration curve to measure the absorbance.

[0057] The results are as follows Figure 2 As shown, the nitrite nitrogen concentration in the effluent treated by the EC-AC-MSL system was 1 mg / L, while that in the effluent treated by the MSL system alone was 0.37 mg / L. The EC-AC-MSL effluent contained less nitrite nitrogen, indicating that the nitrification reaction in the EC-AC-MSL system was more complete, and nitrite nitrogen was converted into nitrate nitrogen.

[0058] (3) Determination of nitrate nitrogen content in the effluent of the EC-AC-MSL system and the MSL system:

[0059] Take an appropriate amount of pretreated water sample and ammonia-free water (as a blank), add them to a 50ml colorimetric tube, dilute to the mark, add 3.0ml of nitrite masking agent and 1.0ml of hydrochloric acid, and mix well. After standing for 10 minutes, measure the absorbance at a wavelength of 220nm using a 20mm path length cuvette with water as a reference (zeroed).

[0060] The results are as follows Figure 3 As shown, the nitrate nitrogen content of the effluent treated by the EC-AC-MSL system is similar to that of the effluent treated by the MSL system alone. The nitrate nitrogen concentration in both the MSL and EC-AC-MSL effluents is approximately 0.38 mg / L, and the nitrate nitrogen removal rate of the EC-AC-MSL system is 87.33%. However... Figure 2 It can be seen that the nitrite content in the EC-AC-MSL system is lower than that in the MSL system, indicating that with a higher nitrite-to-nitrogen conversion rate, more nitrite in the EC-AC-MSL system is converted into nitrogen gas and discharged from the system, thus achieving the denitrification effect.

[0061] (4) Determination of total phosphorus content in the effluent of the EC-AC-MSL system and the MSL system:

[0062] Take 5.00 mL of sample into a stoppered graduated test tube (shake the sample well before sampling to ensure even sampling of any precipitate or suspended sample). Add 4 mL of potassium persulfate (neutralize the solution to neutral if it is stored in an acidic environment). Tightly stopper the test tube and secure the stopper with gauze and thread. Place the tube in a large beaker and then in an autoclave. Heat the beaker until the pressure reaches 1.1 kg / cm². 2 Continue heating for 30 minutes, then stop. Once the pressure returns to zero, remove and cool, then dilute with water to 40 mL. Add 1 mL of ascorbic acid solution to each digest and mix well. After 30 seconds, add 2 mL of molybdate solution and then add water to the 50 mL mark. Mix thoroughly and measure after 15 minutes.

[0063] The results are as follows Figure 4As shown, the total phosphorus content of the effluent treated by the EC-AC-MSL system is similar to that of the effluent treated by the MSL system alone. The total phosphorus concentrations of the MSL effluent and the EC-AC-MSL effluent are 0.69 mg / L and 0.319 mg / L, respectively. The total phosphorus content in the EC-AC-MSL system is lower, and the total phosphorus removal rate of the EC-AC-MSL system in domestic sewage is 78.73%.

[0064] (5) Determination of COD content in the effluent from the EC-AC-MSL system and the MSL system:

[0065] a. Estimate the approximate COD value. After the water sample is retrieved, the approximate COD value should first be estimated based on the source of the water sample, its turbidity, and color. The purpose is to determine which concentration of digestion solution to use.

[0066] b. Accurately pipette 3 mL of uniform water sample into a digestion tube, add 1.00 mL of masking agent, 3.00 mL of digestion solution, and 5.00 mL of catalyst, tighten the cap, and shake well.

[0067] c. Tighten the sealing cap, and insert the digestion tubes into the thermostatic body holes of the COD digestion device that have reached 165°C, and digest for about 22 minutes.

[0068] d. After digestion, transfer the sample solution to a 150mL Erlenmeyer flask, rinse the digestion tube three times with 20mL of distilled water, and combine the rinsing solution into the Erlenmeyer flask. Add 2-3 drops of ferrous ammonium sulfate indicator and back titrate with ferrous sulfate standard bath solution. The endpoint is when the color of the solution changes from yellow through blue-green to reddish-brown. Record the amount of ferrous ammonium sulfate standard solution used and calculate the COD value.

[0069] The results are as follows Figure 5 As shown, the COD concentration of the effluent treated by the EC-AC-MSL system was 20.08 mg / L, while that of the effluent treated by the EC-AC-MSL system was 6.59 mg / L. The EC-AC-MSL system had a lower COD content, and its COD removal rate from domestic sewage was 93.42%, indicating that the EC-AC-MSL system had a better water purification effect and stronger nitrogen and phosphorus removal capabilities.

[0070] The EC-AC-MSL system achieves removal rates of 93.42%, 87.33%, 98.52%, and 78.73% for COD, NO3-N, NH3-N, and TP in domestic sewage, respectively. The effluent COD concentration meets the Class I effluent water quality standard (COD≤15mg / L) of the Surface Water Environmental Quality Standard (GB 3838-2002); the effluent NH3-N concentration meets the Class I effluent water quality standard (NH3-N≤0.15mg / L) of the Surface Water Environmental Quality Standard (GB 3838-2002); and the effluent TP concentration basically meets the Class IV effluent water quality standard (TP≤0.3mg / L) of the Surface Water Environmental Quality Standard (GB 3838-2002).

[0071] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A three-dimensional electrochemically enhanced multilayer soil infiltration system, characterized in that, Includes a main body (5), the top and bottom of the main body (5) are provided with pebble pads (4), the top pebble pad and the bottom pebble pad are between a filling area, the filling area is alternately arranged with a water purification layer (1) and a water circulation layer (2), a first water purification layer is set on the bottom pebble pad, the bottom pebble pad is connected to the water purification layer, the top and surrounding of the first water purification layer is filled with a first water circulation layer, and the layers are alternately arranged in sequence; Inside the main body (5), graphite electrode plates are arranged alternately. The graphite electrode plates are connected to a DC power supply. The graphite electrode plate connected to the positive terminal of the DC power supply is the anode, and the graphite electrode plate connected to the negative terminal of the DC power supply is the cathode. The first graphite electrode plate is set on the first water purification layer, and the graphite electrode plates are arranged alternately at equal intervals. The water-passing layer is composed of zeolite with a particle size of 3-5 mm, ceramsite with a particle size of 5-8 mm, and granular activated carbon with a particle size of 4-8 mm in a dry weight ratio of 1:1:

1. The granular activated carbon is a three-dimensional particle electrode. The water purification layer is made by mixing red soil, biochar, iron-carbon pellets, and rice husks with water in a dry weight ratio of 7:1:1:1, then wrapping the mixture in jute cloth and air-drying it to obtain a square brick-shaped soil block with a length, width, and height of 20cm × 10cm × 5cm.

2. The three-dimensional electrochemically enhanced multilayer soil infiltration system according to claim 1, characterized in that, The length, width and height of the main body (5) are 25cm×25cm×40cm.

3. A three-dimensional electrochemically enhanced multilayer soil infiltration system according to claim 1, characterized in that, The pebble cushion layer (4) is 5cm thick and the pebble particle size is 15~25mm.

4. A three-dimensional electrochemically enhanced multilayer soil infiltration system according to claim 1, characterized in that, The height of the packing area is 30cm, and the clean water layer (1) and the water flow layer (2) are arranged alternately with a height of 5cm.

5. A three-dimensional electrochemically enhanced multilayer soil infiltration system according to claim 1, characterized in that, The graphite electrode plate has a length, width, and thickness of 20cm×20cm×30mm. There are 16 water passage holes with a diameter of 5mm on the plate, and 4 graphite electrode plates are placed alternately at a height of 4~5cm.

6. A three-dimensional electrochemically enhanced multilayer soil infiltration system according to claim 1, characterized in that, The graphite electrode plate is connected to the power supply via copper wire, and waterproof adhesive is applied to the connection between the graphite electrode plate and the copper wire to prevent corrosion of the copper wire.

7. A three-dimensional electrochemically enhanced multilayer soil infiltration system according to claim 1, characterized in that, The lower part of the main body (5) is provided with a water outlet hole with a diameter of 2-3cm. The water outlet hole is connected to a PVC water pipe for drainage.

8. A three-dimensional electrochemically enhanced multilayer soil infiltration system according to claim 1, characterized in that, The material of the main body (5) is plexiglass.

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