1. The utility model provides a villages and small towns landfill leachate nitrogen phosphorus recovery unit, its characterized in that, is in including inner tube, urceolus and setting the inner tube with the water catch bowl at urceolus top, the inner tube wholly presents the shape that is the centrum and straight section of thick bamboo, lower part in proper order for centrum and straight section of thick bamboo in upper portion, the straight section of thick bamboo wall in upper portion of inner tube is provided with the perforation and the bottom is provided with the aeration head, the inner tube bottom with be provided with water inlet and backward flow liquid entry between the aeration head, be provided with the electrochemical reaction district that is located the axis and extends to the straight section of thick bamboo in middle part from middle part centrum downwardly extending in the inner tube, the electrochemical reaction district is including fixed magnesium stick, stainless steel mesh and the external DC power supply who hangs, the magnesium stick is connected external DC power supply's positive pole, encircle the magnesium stick stainless steel mesh is connected external DC power supply's negative pole, the urceolus wholly presents the straight section of upper portion as, The middle part is the back taper body in proper order and straight section of thick bamboo, the lower part is the shape of back taper body and straight section of thick bamboo in proper order, the straight section of thick bamboo in upper portion and the middle part back taper body of urceolus are crystal growth district, be provided with the stainless steel mesh bearing frame who is used for loading the rich magnesium source material of solid in the straight section of thick bamboo in upper portion in crystal growth district, the straight section of thick bamboo in middle part and the lower part back taper body of urceolus are the settling zone, the top of the straight section of thick bamboo in upper portion of urceolus is provided with the connection be provided with the backward flow mouth on the play weir of water catch bowl and the straight section of thick bamboo wall in upper portion, the water catch bowl encircles urceolus section of thick bamboo wall sets up and is provided with the outlet pipe, the backward flow mouth is less than the lowest of water catch bowl, the backward flow mouth with the backward flow liquid entry passes through the back flow connection, the settling zone bottom is provided with the discharge gate.

2. The nitrogen and phosphorus recovery device for the landfill leachate in villages and small towns as claimed in claim 1, wherein a base is arranged between the lower straight cylinder of the outer cylinder and the lower straight cylinder of the inner cylinder, and the base is of a solid structure.

3. The nitrogen and phosphorus recovery device for the landfill leachate in villages and towns as claimed in claim 1, wherein a pH probe is arranged between the stainless steel mesh and the inner cylinder wall.

4. The nitrogen and phosphorus recovery device for the landfill leachate in villages and small towns as claimed in claim 1, wherein the backflow port is arranged at a part of the upper straight cylinder of the outer cylinder, which is higher than the through hole.

5. The nitrogen and phosphorus recovery device for the landfill leachate in villages and small towns as claimed in claim 1, wherein the magnesium rod is fixedly suspended downwards from the top of the upper straight cylinder of the inner cylinder.

6. A method for recovering nitrogen and phosphorus in rural landfill leachate, which is characterized by applying the device for recovering nitrogen and phosphorus in rural landfill leachate disclosed by any one of claims 1 to 5, and comprises the following steps:

pumping the pretreated percolate into an electrochemical reaction zone from a water inlet, applying direct current to an electrode in the electrochemical reaction zone, and rapidly losing electrons by using a magnesium rod as an anode and releasing Mg²⁺While, in the vicinity of the cathode, H⁺To electron generation H₂And the pH value of the solution is increased, so that the condition required by the formation of magnesium ammonium phosphate precipitate is met; the aeration of the aeration head and the irregular shape of the inner cylinder enable the percolate to be fully mixed in the inner cylinder to generate magnesium ammonium phosphate small particles, but the magnesium ammonium phosphate small particles are not attached to the cathode stainless steel net and move upwards along with the water flow, and most of the percolate with the magnesium ammonium phosphate small particles flows into a crystal growth area from a through hole on the upper straight cylinder wall of the inner cylinder; the solid magnesium-rich source material immersed in the leachate is slowly and continuously dissolved, and Mg is carried out on the leachate²⁺Supplementing and promoting the growth of magnesium ammonium phosphate crystals; the liquid flow speed of the crystal growth zone is much lower than that of the liquid in the inner cylinder, so that large-particle magnesium ammonium phosphate crystals can be gradually settled and gathered in the settling zone along the cylinder wall of the inner cylinder, and a discharge hole at the bottom of the settling zone can be periodically opened for recycling magnesium ammonium phosphate; the leachate with suspended micro magnesium ammonium phosphate particles is pumped back to the inner cylinder from the bottom of the inner cylinder through a reflux pipe by a reflux port; the supernatant in the crystal growth area flows into the water collecting tank through the water outlet weir and is discharged from the water outlet pipe.

Background

When the water body is alkalescent and contains three elements of nitrogen, magnesium and phosphorus, the magnesium ammonium phosphate precipitation reaction can occur. The main chemical reaction equation is:

Mg²⁺+PO₄ ^3-+NH₄ ⁺+6H₂O→MgNH₄PO₄·6H₂O↓ (1)

Mg²⁺+HPO₄ ^2-+NH₄ ⁺+6H₂O→MgNH4PO4·6H2O↓+H⁺ (2)

Mg²⁺+H₂PO₄ ^-+NH₄ ⁺+6H₂O→Mg NH₄PO₄·6H₂O↓+2H⁺ (3)

the magnesium ammonium phosphate is a good slow-release phosphate fertilizer, has high fertilizer efficiency utilization rate, and can greatly prevent nitrogen and phosphorus in the fertilizer from entering a water body, thereby reducing the occurrence probability of water eutrophication.

Most of the existing devices for recovering nitrogen and phosphorus from magnesium ammonium phosphate are mechanical stirring type and fluidized bed type, for example, patent document CN104529027B provides a device for removing phosphate in wastewater by a struvite particle crystallization method, and a plug-flow circulation device form is adopted, so that the device has the advantages of large flow, low motor installation power, no need of pipelines and valves, high efficiency and the like, and the rotating speed of a motor can be adjusted by frequency conversion according to the characteristics of water quality, thereby effectively controlling the reflux quantity, further achieving the purpose of energy conservation, being beneficial to reducing the power consumption of phosphate in wastewater in the removal and recovery processes, improving the economic benefit, and forming, precipitating, circulating reflux and water outlet integrated structural forms for struvite particles, and greatly reducing the floor area of process devices without an external precipitation zone or an external reflux device. However, the above patents require a large amount of magnesium source and alkali to be added continuously to meet the reaction requirement, and the cost of the medicament is extremely high, and the dosage of the medicament needs to be controlled; the existing method for replacing the adding of the medicament is electrolysis, but the existing device related to the method is extremely simple, and the problem that magnesium ammonium phosphate is attached to the cathode cannot be solved. For example, patent document CN208948923U provides an array struvite recovery reactor, in which magnesium rods are used as anode and conductive metal cylinder is used as cathode. Therefore, the research and development of the high-efficiency and low-cost magnesium ammonium phosphate reactor have important significance for recycling nitrogen and phosphorus resources by the magnesium ammonium phosphate method.

Disclosure of Invention

The invention aims to provide a device and a method for recovering nitrogen and phosphorus from landfill leachate in villages and towns, and solves the problem of recovering nitrogen and phosphorus resources.

In order to solve the technical problems, the invention adopts the following technical scheme:

the invention relates to a nitrogen and phosphorus recovery device for landfill leachate in villages and small towns, which comprises an inner cylinder, an outer cylinder and a water collecting tank arranged at the top of the inner cylinder and the outer cylinder, wherein the inner cylinder is integrally in the shape of an upper straight cylinder, a middle part of the inner cylinder is sequentially in the shape of a cone and a straight cylinder, and a lower part of the inner cylinder is sequentially in the shape of an inverted cone and a straight cylinder, the wall of the upper straight cylinder of the inner cylinder is provided with a through hole, the bottom of the inner cylinder is provided with an aeration head, a water inlet and a reflux inlet are arranged between the bottom of the inner cylinder and the aeration head, an electrochemical reaction area which is positioned on a central axis and extends downwards from the middle cone to the middle straight cylinder is arranged in the inner cylinder, the electrochemical reaction area comprises a fixedly suspended magnesium rod, a stainless steel mesh and an external direct-current power supply, the magnesium rod is connected with the anode of the external direct-current power supply, the stainless steel mesh surrounding the magnesium rod is connected with the cathode of the external direct-current power supply, and the outer cylinder is integrally in the upper straight cylinder, The middle part is the back taper body in proper order and straight section of thick bamboo, the lower part is the shape of back taper body and straight section of thick bamboo in proper order, the straight section of thick bamboo in upper portion and the middle part back taper body of urceolus are crystal growth district, be provided with the stainless steel mesh bearing frame who is used for loading the rich magnesium source material of solid in the straight section of thick bamboo in upper portion in crystal growth district, the straight section of thick bamboo in middle part and the lower part back taper body of urceolus are the settling zone, the top of the straight section of thick bamboo in upper portion of urceolus is provided with the connection be provided with the backward flow mouth on the play weir of water catch bowl and the straight section of thick bamboo wall in upper portion, the water catch bowl encircles urceolus section of thick bamboo wall sets up and is provided with the outlet pipe, the backward flow mouth is less than the lowest of water catch bowl, the backward flow mouth with the backward flow liquid entry passes through the back flow connection, the settling zone bottom is provided with the discharge gate.

Furthermore, a base is arranged between the lower straight cylinder of the outer cylinder and the lower straight cylinder of the inner cylinder, and the base is of a solid structure.

Further, a pH probe is arranged between the stainless steel net and the wall of the inner cylinder.

Further, the backflow port is arranged at a part of the upper portion of the outer cylinder, which is higher than the through hole.

Still further, the magnesium rod is fixedly suspended downwards from the top of the upper straight cylinder of the inner cylinder.

A nitrogen and phosphorus recovery method for town landfill leachate is applied to the nitrogen and phosphorus recovery device for the town landfill leachate, and the recovery method comprises the following steps: pumping the pretreated percolate into an electrochemical reaction zone from a water inlet, applying direct current to an electrode in the electrochemical reaction zone, and rapidly losing electrons by using a magnesium rod as an anode and releasing Mg²⁺While, in the vicinity of the cathode, H⁺To electron generation H₂And the pH value of the solution is increased, so that the condition required by the formation of magnesium ammonium phosphate precipitate is met; the aeration of the aeration head and the irregular shape of the inner cylinder ensure that the percolate is fully mixed in the inner cylinder to generate magnesium ammonium phosphate granulesBut not attached to the cathode stainless steel net, but moves upwards along with the water flow, and most of percolate with small magnesium ammonium phosphate particles flows into a crystal growth area from a through hole on the upper straight cylinder wall of the inner cylinder; the solid magnesium-rich source material immersed in the leachate is slowly and continuously dissolved, and Mg is carried out on the leachate²⁺Supplementing and promoting the growth of magnesium ammonium phosphate crystals; the liquid flow speed of the crystal growth zone is much lower than that of the liquid in the inner cylinder, so that large-particle magnesium ammonium phosphate crystals can be gradually settled and gathered in the settling zone along the cylinder wall of the inner cylinder, and a discharge hole at the bottom of the settling zone can be periodically opened for recycling magnesium ammonium phosphate; the leachate with suspended micro magnesium ammonium phosphate particles is pumped back to the inner cylinder from the bottom of the inner cylinder through a reflux pipe by a reflux port; the supernatant in the crystal growth area flows into the water collecting tank through the water outlet weir and is discharged from the water outlet pipe.

Compared with the prior art, the invention has the beneficial technical effects that:

the invention provides a full-automatic nitrogen and phosphorus recovery device for village and town landfill leachate and a recovery method thereof, and provides a full-automatic nitrogen and phosphorus recovery device for magnesium ammonium phosphate without an additional medicament.

Drawings

The invention is further illustrated in the following description with reference to the drawings.

Fig. 1 is a schematic structural diagram of the nitrogen and phosphorus recovery device for village and town landfill leachate of the invention.

Description of reference numerals: 1-an electrochemical reaction zone, 2-a crystal growth zone, 3-a precipitation zone, 4-a magnesium rod, 5-a stainless steel net, 6-an aeration head, 7-a perforation, 8-a solid magnesium-rich source material, 9-a stainless steel net bearing frame, 10-a return port, 11-a return pump, 12-a return pipe, 13-a discharge port, 14-a water inlet, 15-a water outlet weir, 16-a water collecting tank and 17-a water outlet pipe.

Detailed Description

Example 1

As shown in fig. 1, a nitrogen and phosphorus recovery device for landfill leachate in villages and small towns comprises an inner cylinder, an outer cylinder and a water collecting tank 16 arranged at the top of the inner cylinder and the outer cylinder, wherein the inner cylinder is integrally in the shape of a straight cylinder at the upper part, a cone and a straight cylinder are sequentially arranged at the middle part, and an inverted cone and a straight cylinder are sequentially arranged at the lower part, a perforation 7 is arranged on the straight cylinder wall at the upper part of the inner cylinder, an aeration head 6 is arranged at the bottom, a water inlet 14 and a reflux inlet are arranged between the bottom of the inner cylinder and the aeration head 6, an electrochemical reaction area 1 which is arranged on an axle wire and extends from the middle cone to the straight cylinder at the middle part is arranged in the inner cylinder, the electrochemical reaction area 1 comprises a fixedly suspended magnesium rod 4, a stainless steel mesh 5 and an external direct current power supply, the magnesium rod 4 is connected with the anode of the external direct current, the outer barrel is integrally in the shape of a straight barrel at the upper part, an inverted cone and a straight barrel at the middle part, and an inverted cone and a straight barrel at the lower part, the straight barrel at the upper part and the inverted cone at the middle part of the outer barrel are crystal growth areas 2, a stainless steel mesh bearing frame 9 used for loading solid magnesium-rich source materials 8 is arranged in the straight barrel at the upper part of the crystal growth areas 2, the straight barrel at the middle part and the inverted cone at the lower part of the outer barrel are sedimentation areas 3, the top of the straight barrel at the upper part of the outer barrel is provided with a water outlet weir 15 connected with the water collecting tank 16, a backflow port 10 is arranged on the barrel wall of the straight barrel at the upper part, the water collecting tank 16 surrounds the barrel wall of the outer barrel and is provided with a water outlet pipe 17, the backflow port 10 is lower than the lowest part of the water collecting tank 16, the backflow port 10 is connected with a backflow liquid inlet through a backflow pipe 12, and a discharge port 13 is arranged at the bottom of the sedimentation area 3.

When the device for recovering nitrogen and phosphorus in landfill leachate in villages and towns of embodiment 1 is used, the leachate after pretreatment is pumped into the electrochemical reaction area 1 from the water inlet 14, and after direct current is applied to electrodes in the electrochemical reaction area 1, the magnesium rod 4 is taken as an anode to rapidly lose electrons, andrelease Mg²⁺While, in the vicinity of the cathode, H⁺To electron generation H₂And the pH value of the solution is increased, so that the condition required by the formation of magnesium ammonium phosphate precipitate is met; the aeration of the aeration head 6 and the irregular shape of the inner cylinder enable the percolate to be fully mixed in the inner cylinder to generate magnesium ammonium phosphate small particles, but the magnesium ammonium phosphate small particles are not attached to the cathode stainless steel net 5, but move upwards along with the water flow, and most of the percolate with the magnesium ammonium phosphate small particles flows into the crystal growth area 2 from the through hole 7 of the upper straight cylinder wall of the inner cylinder; the solid magnesium-rich source material 8 immersed in the leachate is slowly and continuously dissolved, and Mg is carried out on the leachate²⁺Supplementing and promoting the growth of magnesium ammonium phosphate crystals; the liquid flow speed of the crystal growth area 2 is much smaller than that of the liquid in the inner cylinder, so that large-particle magnesium ammonium phosphate crystals can gradually settle down and gather in the sedimentation area 3 along the cylinder wall of the inner cylinder, and the discharge hole 13 at the bottom of the sedimentation area 3 can be periodically opened for recycling magnesium ammonium phosphate; the backflow port 10 pumps the percolate with suspended micro magnesium ammonium phosphate particles back to the inner cylinder from the bottom of the inner cylinder through the backflow pipe 12; the supernatant of the crystal growth zone 2 flows into the water collection tank 16 through the effluent weir 15 and is discharged from the effluent pipe 17.

The nitrogen and phosphorus recovery device for the landfill leachate in villages and towns in the embodiment 1 provides an ammonium magnesium phosphate precipitation reactor for intermittently and continuously providing a magnesium source inside, so that the problem of nitrogen and phosphorus resource recovery is solved; the recovery device is mainly divided into an electrochemical reaction area 1, a crystal growth area 2 and a precipitation area 3 of an outer cylinder and a water collecting tank 16 at the top, wherein the electrochemical reaction area 1 is positioned on the central axis of the inner cylinder, extends downwards from a middle cone to a middle straight cylinder and comprises a magnesium rod 4 and a surrounding stainless steel net 5; an aeration head 6 is arranged at the bottom of the inner cylinder, and the diameter of the aeration head 6 is smaller than that of the inner cylinder; the crystal growth area 2 is positioned in the upper straight cylinder and the middle inverted cone of the outer cylinder, a stainless steel mesh bearing frame 9 is arranged in the upper straight cylinder of the crystal growth area 2 and is used for filling a solid magnesium-rich source material 8, and the upper end of the stainless steel mesh bearing frame is flush with the top of the perforated area 7; the settling zone 3 is located in the middle straight cylinder and the lower inverted cone part of the outer cylinder, the space of the lower inverted cone part is in a decreasing trend from top to bottom, and a discharge hole 13 is formed in the bottom of the lower inverted cone part.

Wherein the solid magnesium-rich source material 8 is a solid magnesium-rich source material such as magnesium-containing ore.

Specifically, a base is arranged between the lower straight cylinder of the outer cylinder and the lower straight cylinder of the inner cylinder, and the base is of a solid structure.

In this embodiment 1, the base is a solid structure to ensure the load bearing.

Specifically, a pH probe is arranged between the stainless steel mesh 5 and the inner cylinder wall.

Specifically, the return pipe 12 is provided with a return pump 11.

Specifically, the return opening 10 is provided at a portion of the upper portion of the outer cylinder which is vertically higher than the perforation 7.

In this embodiment 1, the return port 10 is lower than the lowest part of the water collection tank 16 and higher than the highest part of the perforation 7, and is connected with a return pipe 12, which pumps the percolate with suspended micro magnesium ammonium phosphate particles from the bottom of the inner cylinder back to the inner cylinder by a return pump 11.

Specifically, the magnesium rod 4 is fixedly suspended downwards from the top of a straight cylinder at the upper part of the inner cylinder.

Example 2

A nitrogen and phosphorus recovery method for town landfill leachate is applied to the nitrogen and phosphorus recovery device for the town landfill leachate, and the recovery method comprises the following steps:

the leachate after pretreatment is pumped into the electrochemical reaction zone 1 from the water inlet 14, and after direct current is applied to the electrodes in the electrochemical reaction zone 1, the magnesium rod 4 as an anode rapidly loses electrons and releases Mg²⁺While, in the vicinity of the cathode, H⁺To electron generation H₂And the pH value of the solution is increased, so that the condition required by the formation of magnesium ammonium phosphate precipitate is met; the aeration of the aeration head 6 and the irregular shape of the inner cylinder enable the percolate to be fully mixed in the inner cylinder to generate magnesium ammonium phosphate small particles, but the magnesium ammonium phosphate small particles are not attached to the cathode stainless steel net 5, but move upwards along with the water flow, and most of the percolate with the magnesium ammonium phosphate small particles flows into the crystal growth area 2 from the through hole 7 of the upper straight cylinder wall of the inner cylinder; the solid magnesium-rich source material 8 immersed in the leachate is slowly releasedContinuously dissolving to obtain Mg in the percolate²⁺Supplementing and promoting the growth of magnesium ammonium phosphate crystals; the liquid flow speed of the crystal growth area 2 is much smaller than that of the liquid in the inner cylinder, so that large-particle magnesium ammonium phosphate crystals can gradually settle down and gather in the sedimentation area 3 along the cylinder wall of the inner cylinder, and the discharge hole 13 at the bottom of the sedimentation area 3 can be periodically opened for recycling magnesium ammonium phosphate; the backflow port 10 pumps the percolate with suspended micro magnesium ammonium phosphate particles back to the inner cylinder from the bottom of the inner cylinder through the backflow pipe 12; the supernatant of the crystal growth zone 2 flows into the water collection tank 16 through the effluent weir 15 and is discharged from the effluent pipe 17.

Specifically, the return pipe 12 is provided with a return pump 11.

The invention provides a full-automatic nitrogen and phosphorus recovery device for village and town landfill leachate and a recovery method thereof, and provides a full-automatic nitrogen and phosphorus recovery device for magnesium ammonium phosphate without an additional medicament.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.