Method for treating groundwater ammonia nitrogen cycle

Abstract

The application provides a groundwater ammonia nitrogen cycle treatment method, which comprises the following steps: according to the pollution range, depth and pollutant concentration of groundwater, a groundwater extraction well and a recharge well system are designed; the polluted groundwater is extracted to a sedimentation tank by the extraction well; the pH value is adjusted, blow-off treatment is carried out, and part of ion state ammonium in the polluted groundwater is converted into gaseous ammonia; after gas-liquid separation, the groundwater enters activated carbon adsorption; the groundwater enters an electrochemical equipment for deep denitrification; and after treatment, the groundwater is recharged to the underground; the application can be adjusted according to the distribution of groundwater pollution concentration and the treatment effect in the process, has the characteristics of partition control and precise repair; the application is coupled with the electrochemical equipment by the secondary blow-off equipment, the secondary blow-off realizes preliminary denitrification of ammonia nitrogen in water, the water treatment capacity is large, the ammonia nitrogen concentration in water is rapidly reduced, the electrochemical equipment adopts a penetrating porous electrode, the applicable range of the water pollutant concentration is wide, the deep treatment of ammonia nitrogen in water can be realized, and the water treatment efficiency is high and the energy consumption is low.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of groundwater remediation treatment, and particularly relates to a method for treating ammonia-nitrogen in groundwater. BACKGROUND

[0002] With the development of petroleum, chemical, food and pharmaceutical industries and agriculture, and the continuous improvement of people's living standards, the content of ammonia-nitrogen in municipal sewage and landfill leachate has increased sharply. The problem of ammonia-nitrogen pollution in industrial land soil and groundwater has been widely concerned. SUMMARY

[0003] In view of the deficiencies in the prior art, the present application aims to provide a method for treating ammonia-nitrogen in groundwater, which can effectively convert ammonia-nitrogen in groundwater into nitrogen gas harmless to the environment and human body, and solve the problem of remediation and improvement of contaminated groundwater.

[0004] To achieve the above-mentioned purpose, the solution of the present application is as follows:

[0005] A method for treating ammonia-nitrogen in groundwater, comprising the following steps:

[0006] (1) arranging the positions of a groundwater extraction well system and a groundwater recharge well system, and controlling the extraction and recharge amounts of groundwater by a vacuum extraction pump and a recharge barrel;

[0007] (2) extracting groundwater to a sedimentation tank on the ground, adjusting the pH of the settled groundwater, discharging it into a stripping tower for secondary series stripping treatment to preliminarily reduce the ammonia-nitrogen concentration in the water, discharging the contaminated wastewater after stripping treatment into an intermediate tank for temporary storage and buffering, and then discharging it into an electrochemical device for deep treatment; discharging the exhaust gas after gas-liquid separation, and discharging the wastewater into a sedimentation tank;

[0008] (3) using activated carbon adsorption treatment on the gas phase after gas-liquid separation in step (2);

[0009] (4) discharging the wastewater after electrochemical deep treatment in step (2) into a detection tank, and recharging it into the ground after detection to achieve the standard, thereby realizing the cyclic remediation of groundwater.

[0010] Further, in step (1), the groundwater extraction well system and the groundwater recharge well system are arranged at intervals; the extraction pipeline in the groundwater extraction well system is composed of a plurality of extraction wells connected in series, and the recharge pipeline in the groundwater recharge well system is composed of a plurality of recharge wells connected in series; the extraction pipeline and the recharge pipeline, the distance between the extraction well and the recharge well are reasonably set through extraction / injection test, so as to realize the coverage of the remediation area.

[0011] When the groundwater extraction well system extracts and the groundwater recharge well system recharges, the circulation efficiency and treatment capacity are adjusted, and the treatment effect of the groundwater in different regions is accurately controlled by controlling the valves of the extraction and recharge pipelines in different regions.

[0012] Further, in step (2), when adjusting the pH of the water body, the pH of the wastewater entering the stripping device is adjusted by liquid alkali to maintain 11.5-12.

[0013] Further, in step (2), during the stripping treatment, a two-stage series stripping tower is used, the stripping tower is filled with polypropylene filler, the groundwater is uniformly sprinkled on the filler from the top of the stripping tower to form water droplets flowing to the bottom of the stripping tower, and the centrifugal fan blows air from the bottom of the stripping tower to make the gas and water fully contact, and the free ammonia escapes from the water and is carried away by the air.

[0014] Further, in step (3), after gas-liquid separation, the exhaust gas generated by the first-stage stripping tower and the exhaust gas generated by the second-stage stripping tower are respectively adsorbed into the activated carbon adsorber, and the activated carbon adsorber is installed with a centrifugal exhaust fan at the other end, which exhausts the exhaust gas and then discharges it through a chimney.

[0015] Further, in step (4), during the electrochemical advanced treatment, a through-type electrochemical device is used to treat the wastewater, and a large number of free radicals with strong oxidizing properties are generated on the electrode by using the chlorine ions in the water, so as to degrade the pollutants.

[0016] Further, in step (4), the groundwater treated by the electrochemical advanced treatment is discharged into a detection pool, and if the detection is qualified, the groundwater is recharged into the ground, otherwise, the groundwater is discharged into a sedimentation tank for re-treatment.

[0017] Further, in steps (2) and (4), nitrogen and oxygen concentration online monitoring devices, pH online monitoring devices, and chlorine ion concentration online monitoring devices are installed in the sedimentation tank, the intermediate tank, and the detection tank to monitor the operation effect of the ammonia-nitrogen circulation treatment of the groundwater.

[0018] Further, flow meters are installed in the extraction pipeline and the recharge pipeline to record the flow rate and flow during the treatment process.

[0019] Due to the adoption of the above scheme, the beneficial effects of the present application are as follows:

[0020] (1) The present application can reasonably design the positions of the water extraction well and the recharge well, arrange the spacing of the extraction pipeline and the recharge pipeline, and realize the effective coverage of the groundwater pollution area by arranging the groundwater extraction well system and the groundwater recharge well system.

[0021] (2) The application can dynamically control the extraction and recharge efficiency of the corresponding area of groundwater and the treatment capacity according to the concentration distribution of pollution in groundwater and the concentration change of pollutants in the treatment process, realizes the purpose of key extraction and key recharge in key areas, and thus realizes the precise repair and partition control of groundwater.

[0022] (3) The groundwater ammonia nitrogen circulating treatment method provided by the application comprises the steps of extraction, precipitation, secondary series blow stripping treatment, electrochemical deep treatment and detection of recharge water quality, so that the whole groundwater treatment process is recycled, thereby converting the ammonia nitrogen which is harmful to the environment and human body into non-toxic nitrogen, and providing a solution for groundwater treatment projects which do not have the condition of pipe installation. In addition, the secondary blow stripping equipment is coupled with the electrochemical equipment, the secondary blow stripping realizes preliminary denitrification of ammonia nitrogen in water, the water treatment capacity is large, the ammonia nitrogen concentration in water is rapidly reduced, the electrochemical equipment adopts a penetrating porous electrode, the operation voltage is low, the current efficiency is high, the service life of the electrode is long, the concentration range of the treated pollutants in water is wide, the deep treatment of ammonia nitrogen in water can be realized, and the water treatment efficiency is high and the energy consumption is low.

[0023] (4) In the application, the recharge adopts a gravity flow different well recharge mode, no pressurizing device is needed in the recharge process, the requirements for pipeline connection and sealing performance are low, the installation is easy, the maintenance is convenient, and the operation cost is lower than that of the same well extraction and recharge mode. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 It is a device schematic diagram of the groundwater ammonia nitrogen circulating treatment process of the application.

[0025] Figure 2 It is a process flow diagram of the groundwater ammonia nitrogen circulating treatment process of the application.

[0026] Figure 3 It is a schematic diagram of the extraction well and pipeline structure of the groundwater ammonia nitrogen circulating treatment process of the application. BRIEF DESCRIPTION OF DRAWINGS:

[0028] 1-vacuum extraction pump, 2-settling tank, 3-centrifugal pump, 4-automatic dosing device, 5-blow stripping tower, 6-centrifugal fan, 7-gas-liquid separator, 8-intermediate tank, 9-bag filter, 10-penetrating electrochemical equipment, 11-activated carbon adsorber, 12-exhaust fan, 13-chimney, 14-pool to be detected, 15-recharge barrel, 16-groundwater circulating extraction and recharge system, 16-1-well table, 16-2-closed well, 16-3-dropper, 16-4-well cap, 16-5-gas check valve, 16-6-elbow, 16-7-hard transparent pipe, 16-8-negative pressure gauge, 16-9-extraction and injection water pipeline, 16-10-valve, 16-11-extraction and recharge water main, 16-12-pipeline with hard transparent pipe, 17-groundwater extraction well system, 18-groundwater recharge well system. DETAILED DESCRIPTION

[0029] The application provides a method for treating ammonia nitrogen in groundwater. The valve of the extraction and recharge system is controlled according to the concentration distribution of pollutants in the groundwater and the change of the concentration of pollutants in the groundwater during the treatment process, and the groundwater is extracted and recharged in different zones; the groundwater is extracted to a sedimentation tank on the ground, and then enters a stripping tower after adjusting the pH, so that two-stage serial stripping is carried out to reduce the concentration of ammonia nitrogen in the water; the groundwater after the stripping treatment enters an electrochemical device, active chlorine generated by the electrochemical device reacts with the residual ammonia nitrogen in the water, and ion ammonia (NH4 + ) is degraded into nitrogen, so that the ammonia nitrogen in the groundwater is further removed, and deep denitrification treatment is completed; the groundwater after the deep treatment is detected to be qualified and is recharged to the underground, so that the treatment of the groundwater is recycled.

[0030] The method for treating ammonia nitrogen in groundwater provided by the application comprises the following steps:

[0031] (1) The positions of the groundwater extraction well system 17 and the groundwater recharge well system 18 are reasonably arranged, and the extraction and recharge amounts of the groundwater are controlled in different zones by the vacuum extraction pump 1 and the recharge barrel 15; the groundwater circulation pumping and recharging system 16 comprises the groundwater extraction well system 17 and the groundwater recharge well system 18;

[0032] (2) The groundwater is extracted to a sedimentation tank 2 on the ground, the pH of the sedimented groundwater is adjusted, and then the groundwater is discharged into a stripping tower 5 to be subjected to two-stage serial stripping treatment, so that the concentration of ammonia nitrogen in the water is preliminarily reduced; the contaminated wastewater after the stripping treatment is discharged into an intermediate tank 8 to be temporarily stored and buffered, and then is discharged into an electrochemical device to be subjected to deep treatment; the exhaust gas after the gas-liquid separation is discharged; and the wastewater is discharged into a sedimentation tank;

[0033] (3) The gas phase after the gas-liquid separation in step (2) is subjected to active carbon adsorption treatment;

[0034] (4) The wastewater after the electrochemical deep treatment in step (2) is discharged into a detection tank, and is recharged to the underground after the detection is qualified, so that the groundwater is recycled and repaired.

[0035] In step (1), the groundwater extraction well system 17 and the groundwater recharge well system 18 are arranged at intervals; the extraction pipeline in the groundwater extraction well system 17 is composed of a plurality of extraction wells connected in series, and the recharge pipeline in the groundwater recharge well system 18 is composed of a plurality of recharge wells connected in series.

[0036] The effective radii of the water extraction and the water injection in the contaminated area are calculated through the water extraction / injection test, the intervals of the extraction pipeline and the recharge pipeline are reasonably set, the flow meters are installed on the extraction pipeline and the recharge pipeline, the flow rate and the flow during the treatment process are recorded, so that the positions of the groundwater extraction well system 17 and the groundwater recharge well system 18 are arranged, and the coverage of the repair area is realized, as shown in Figure 1 .

[0037] In step (2), if Figure 1 As shown, a vacuum extraction pump 1 is used to extract the contaminated groundwater through an extraction well to a sedimentation tank 2 for sedimentation, and after sedimentation, a centrifugal pump 3 is used to pump the contaminated groundwater into a stripping tower 5.

[0038] In step (2), when adjusting the pH value of the water body, liquid caustic soda is added by the automatic dosing device 4 to maintain the pH at 11.5-12 to ensure the effectiveness of the stripping in removing ammonia nitrogen. The automatic dosing device 4 is composed of a metering pump (model: DJD-500L) and an online pH meter (model: EL-PH2.0).

[0039] In step (2), during the stripping treatment, a two-stage stripping tower 5 is connected in series (the groundwater first enters the first stripping tower, and then the wastewater is pumped into the second stripping tower by a lift pump) for denitrification treatment. The stripping tower 5 is filled with a 3m thick filler (polypropylene multi-faceted hollow balls) to promote sufficient contact between air and water. In the stripping tower 5, the groundwater is sprayed down from the top of the stripping tower 5, flows downward in a thin film along the surface of the filler, and forms uniform droplets that flow to the bottom of the stripping tower 5. At the same time, a centrifugal fan 6 is used to blow air from the bottom of the stripping tower 5, and contacts the wastewater from bottom to top in countercurrent, so that the air and water are fully contacted, and free ammonia escapes from the water and is carried away by the air.

[0040] The ammonia nitrogen dissolved in the water is further transferred through the gas-liquid interface to the gas phase, thereby achieving the purpose of removing ammonia nitrogen. The reaction equation of the ammonia nitrogen removal process is as follows:

[0041]

[0042] Ammonia nitrogen in water is mostly in the form of ionized ammonia (NH4 + ) and free ammonia (NH3), which exist in equilibrium, a relationship influenced by pH. When the pH is around 11, the NH3 content is generally above 90%. The continuous discharge of gas during the stripping process changes the ammonia concentration in the gas phase, causing its actual concentration to remain below the equilibrium concentration under these conditions. Ultimately, dissolved ammonia in the wastewater continuously crosses the gas-liquid interface, allowing NH3 to be removed from the wastewater, often using air as a carrier.

[0043] In step (3), after being treated by the gas-liquid separator 7, the waste gas generated by the first-stage stripping tower and the waste gas generated by the second-stage stripping tower respectively enter the activated carbon adsorber 11 for adsorption. An exhaust fan 12 is installed at the other end of the activated carbon adsorber 11. The gas phase in the waste gas is treated by activated carbon adsorption and discharged through the exhaust pipe (chimney 13), and the liquid phase in the waste gas is discharged back to the sedimentation tank 2.

[0044] The first-stage stripping tower and the second-stage stripping tower are both CTT-500 stripping towers, the activated carbon adsorber 11 is an XF-1400 activated carbon adsorber, and the honeycomb-shaped activated carbon is arranged in the activated carbon adsorber 11. The tail-end air extractor 12 uses a 4-79 No 14C centrifugal fan.

[0045] In step (2), the wastewater is temporarily buffered in the intermediate pool 8 for the next electrochemical reaction. The intermediate pool 8 is arranged between the two-stage series-connected stripping towers 5 and the penetration-type electrochemical device 10. The ammonia-nitrogen concentration in the water outlet of the stripping tower 5 is monitored by an online monitoring device. The wastewater that does not reach the treatment effect is discharged into the sedimentation pool 2. A liquid level gauge is arranged in the intermediate pool 8. If the liquid level is too low, the flow of water discharged from the stripping tower 5 is appropriately increased. If the liquid level is too high, the excessive water in the intermediate pool 8 is discharged into the sedimentation pool 2, so as to avoid overloading of the penetration-type electrochemical device 10 or overflow of the water in the intermediate pool 8.

[0046] In step (2), a bag filter 9 is used to filter the groundwater entering the penetration-type electrochemical device 10 before the electrochemical treatment, so as to prevent the penetration-type electrochemical device 10 from being blocked and the electrochemical treatment effect from being affected. Then, the penetration-type electrochemical device 10 is used to treat the temporarily buffered wastewater. The existing chloride ions in the water are used to make the electrode generate a large amount of free radicals with strong oxidizing property, so as to degrade the pollutants. The active chlorine generated by the device reacts with the ammonia-nitrogen, so as to degrade the ionic ammonia in the water body into nitrogen, and further remove the ammonia-nitrogen in the groundwater. The penetration-type electrochemical device 10 is composed of two-stage series-connected electrochemical devices. The first stage mainly removes the organic matters in the water by direct oxidation, and the second stage catalyzes the chloride ions in the water to generate hypochlorite, so as to remove the ammonia-nitrogen in the water.

[0047] In step (4), the groundwater after the deep treatment is discharged into a detection pool 14, and is injected into a recharge barrel 15 by a pipeline pump, and is then pressed to the groundwater circulation pumping and recharging system 16 by gravity. Then, the groundwater is treated by step (1), so as to realize the circulation treatment of the groundwater. The recharge is performed in a manner of using different wells, so as to form the circulation of the groundwater between the pumping and recharging wells in a local area, accelerate the local groundwater circulation, accelerate the groundwater renewal speed, and increase the removal efficiency of the groundwater pollutants. The recharge barrel 15 is arranged on a 1.2m high platform, so as to increase the water head, increase the gravity potential energy, and increase the injection pressure.

[0048] The nitrogen and oxygen concentration online monitoring device, the pH online monitoring device, and the chloride ion concentration online monitoring device are arranged in the sedimentation pool 2, the intermediate pool 8, and the detection pool 14, so as to monitor the operation effect of the ammonia-nitrogen circulation treatment of the groundwater.

[0049] Specifically, as shown in FIG. 1, the groundwater is treated by the following steps. Figure 3As shown, the structures of the groundwater extraction well system 17 and the groundwater recharge well system 18 are basically the same. A well platform 16-1 is set up on the ground where the closed well 16-2 is located; a well cap 16-4 is set up on the top of the closed well 16-2, which is used to seal the wellhead. A dropper 16-3 passes through the well cap 16-4 and is inserted into the closed well 16-2; a gas check valve 16-5 is installed on the surface of the well cap 16-4, which is used to adjust the vacuum environment of the closed well 16-2 hole. The groundwater extraction well system 17 does not need to be equipped with a gas check valve 16-5; the dropper 16-3 passes through the well cap 16-4 and is connected to the pipe 16- 12 are connected by direct plugging; the outside of the pipe 16-12 with a hard transparent tube is a hard transparent tube 16-7, and the hard transparent tube 16-7 is used to observe the water flow in the well pipe; the pipe 16-12 with a hard transparent tube is installed with a negative pressure gauge 16-8, which is connected to the pumping and injection water pipe 16-9 through the elbow 16-6; the pumping and injection water pipe 16-9 is collected through a tee and connected to the pumping and injection water main pipe 16-11 through the valve 16-10, wherein the valve 16-10 is used to control the water flow speed and flow in the pipe, and the pumping and injection water main pipe 16-11 is arranged in parallel on the flat ground.

[0050] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0051] Example:

[0052] like Figure 2 As shown, at steps S1 and S8, the groundwater circulation pumping well system 16 includes a groundwater extraction well system 17 and a groundwater recharge well system 18. The extraction pipelines and recharge pipelines in the system are arranged in sequence, and each pipeline is connected to several extraction wells and recharge wells in sequence. Figure 1 The treated groundwater is pumped into the recharge barrel 15 through a pipeline pump and then recharged into the ground through gravity flow from the well.

[0053] Furthermore, the spacing between the recharge and extraction lines, as well as the spacing between the extraction and recharge wells, was determined based on calculations from pumping / injection tests within the treatment area. Based on stable water level monitoring data obtained during actual pumping / injection tests, the parameters were calculated using the Dupuit method for submerged constant flow, and adjustments were made to determine the influence radius of the pumping / injection system.

[0054] 1. Dupuit formula for submerged wells

[0055]

[0056]

[0057] where:

[0058] K—permeability coefficient (m / d);

[0059] Q—pumping well yield (m 3 / d);

[0060] R—influence radius (m);

[0061] H0—aquifer thickness (m);

[0062] s1—water level drawdown in No. 1 observation well (m);

[0063] s2—water level drawdown in No. 2 observation well (m);

[0064] s w —water level drawdown in well (m);

[0065] r w —well radius (m).

[0066] 2. A formula for calculating the permeability coefficient of one observation hole

[0067]

[0068] where:

[0069] K—permeability coefficient (m / d);

[0070] Q—pumping well yield (m 3 / d);

[0071] h—observation well phreatic thickness (m);

[0072] h w —pumping well phreatic thickness (m);

[0073] r—distance from observation well to central well (m);

[0074] r w —well radius (m).

[0075] 3. A formula for calculating the permeability coefficient of two observation holes (phreatic well Thiem formula)

[0076]

[0077]

[0078] where:

[0079] K—permeability coefficient (m / d);

[0080] Q - pumping well yield (m 3 / d) ;

[0081] H0 - aquifer thickness (m) ;

[0082] h1 - No. 1 observation well phreatic water thickness (m) ;

[0083] h2 - No. 2 observation well phreatic water thickness (m) ;

[0084] s1 - No. 1 observation well water level drawdown (m) ;

[0085] s2 - No. 2 observation well water level drawdown (m) ;

[0086] r1 - No. 1 observation well to central well distance (m) ;

[0087] r2 - No. 2 observation well to central well distance (m).

[0088] 4. Influence radius

[0089]

[0090] In the formula:

[0091] K - permeability coefficient (m / d) ;

[0092] Q - pumping well yield (m 3 / d) ;

[0093] H0 - aquifer thickness (m) ;

[0094] s1 - No. 1 observation well water level drawdown (m) ;

[0095] s2 - No. 2 observation well water level drawdown (m) ;

[0096] r1 - No. 1 observation well to central well distance (m) ;

[0097] r2 - No. 2 observation well to central well distance (m).

[0098] Further, the extraction pipeline is connected only with the vacuum extraction pump 1, and a valve is arranged at the end connection. The recharge pipeline is connected with both the vacuum extraction pump 1 and the recharge barrel 15, and valves are arranged at both ends of the recharge pipeline.

[0099] Further, a separate valve is arranged for each extraction well and recharge well to be connected with the extraction pipeline and the recharge pipeline, as shown in Figure 3 .

[0100] Further, during the circulation process, according to the actual groundwater remediation effect, the opening and closing of the valves of each pipeline are controlled to realize partition control and precise remediation.

[0101] Furthermore, at the initial stage of contaminated groundwater treatment, the extraction pipeline valve and the reinjection end valve of the reinjection pipeline are opened, and the reinjection well and extraction well valves of the corresponding pipelines are opened, and the vacuum extraction pump 1 and the reinjection barrel 15 are circulated at full load to quickly reduce the pollutant concentration.

[0102] Furthermore, in the middle and late stages of contaminated groundwater treatment, valves are opened and closed in different areas according to the treatment effects in each area to reduce system energy consumption: in areas with good treatment effects, valves of some pipelines and wells are closed to reduce the amount of water pumped; in areas with high pollutant concentrations or where there is a tailing phenomenon in the pollution concentration, the valves at the reinjection end of the reinjection pipeline are closed, the valves of the extraction pipeline and the valves at the extraction end of the reinjection pipeline are opened, and the valves of the extraction wells and reinjection wells of the corresponding pipelines are opened to enhance the pollutant removal rate in the area.

[0103] like Figure 2 As shown, in step S2, the extracted contaminated groundwater is discharged into sedimentation tank 2, where suspended solids are removed by sedimentation. A weir is provided between the two sedimentation tanks 2 to control the water level and evenly distribute the water flow. Sedimentation tank 2 is equipped with real-time monitoring equipment to monitor the ammonia nitrogen concentration, pH value, and chloride ion concentration in real time.

[0104] In step S3, the ammonia nitrogen in the groundwater is stripped. During the stripping process, the automatic dosing device 4 monitors the pH value online in real time and adjusts the pH value of the groundwater by adjusting the amount of liquid alkali injected. Adjusting the pH value of the groundwater to 11.5 can remove the ionized ammonium (NH4 + ) is converted into a large amount of free ammonia (NH3). Gas stripping allows the free ammonia in the solution to cross the gas-liquid interface and form gaseous ammonia (NH3). In this embodiment, the groundwater ammonia nitrogen treatment is a two-stage series stripping process. After the first stage of stripping, the remaining ammonia nitrogen is discharged into the second stage stripping equipment along with the solution.

[0105] Free ammonia (NH3) and ionized ammonium (NH4 + ) can exist in ammonia nitrogen wastewater in equilibrium as shown in formula (2).

[0106]

[0107] In step S401, the water after stripping treatment is discharged from the equipment into the intermediate tank 8 for temporary storage, and is injected into the electrochemical deep treatment device for degradation (S501). There is a real-time monitoring device in the intermediate tank 8 to monitor the ammonia nitrogen concentration and pH value in the intermediate tank 8 in real time.

[0108] At step S402, the waste gas generated by stripping is discharged into the gas-liquid separator 7. After gas-liquid separation, the waste gas is disposed of in two steps S502 and S503. The water is discharged back to the sedimentation tank 2 through the water channel (S502), and the gas is injected into activated carbon for adsorption through the gas channel (S503) and then discharged through the exhaust pipe.

[0109] At step S501, before the groundwater enters the electrochemical processor for treatment, the groundwater needs to be pretreated by filtering through the bag filter 9 provided with the electrochemical equipment. The first-stage electrochemical reaction directly oxidizes the anode to remove organic matter in the water. The second stage produces hypochlorite by catalyzing the chlorine ions, and the hypochlorite removes ammonia nitrogen in the water by breakpoint chlorination. The main product (nitrogen) obtained by the ammonia nitrogen treatment process of the embodiment can not need to be further treated. As the electrochemical reaction occurs, the pH value of the water body can gradually decrease.

[0110] At steps S6 and S7, the groundwater treated by the above-mentioned stripping and electrochemical treatment is discharged into the detection tank 14 for detection. If it meets the recharge standard, it is subjected to recharge treatment. The detection tank 14 has real-time monitoring equipment to monitor the ammonia nitrogen concentration, pH value, and chlorine ion concentration in the intermediate tank in real time.

[0111] The above description of the embodiments is to facilitate the understanding and use of the present application by those of ordinary skill in the art. Those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without having to go through creative labor. Therefore, the present application is not limited to the above-mentioned embodiments. Improvements and modifications made by those skilled in the art based on the principles of the present application without departing from the scope of the present application should be within the scope of protection of the present application.

Claims

1. A method for circulating ammonia nitrogen in groundwater, characterized by: It includes the following steps: (1) Arrange the locations of the groundwater extraction well system and the groundwater recharge well system, control the groundwater extraction and recharge volume by vacuum extraction pumps and recharge barrels, and place the recharge barrels on a 1.2m high platform to increase the water head, thereby increasing the gravitational potential energy and injection pressure; (2) Groundwater is extracted to a sedimentation tank on the ground, the pH of the groundwater after precipitation is adjusted, and the groundwater is discharged into a stripping tower for secondary series stripping treatment to initially reduce the concentration of ammonia nitrogen in the water. The contaminated wastewater after stripping treatment is discharged into an intermediate tank for temporary buffering, and then discharged into an electrochemical device for deep treatment; the waste gas from the stripping is discharged after gas-liquid separation, and the wastewater is discharged into a sedimentation tank; (3) The gas phase after gas-liquid separation in step (2) is treated by activated carbon adsorption; (4) The wastewater after electrochemical deep treatment in step (2) is discharged into the inspection pool, and after the test meets the standards, it is recharged into the ground to achieve groundwater circulation repair; Wherein, in step (4), the wastewater after electrochemical deep treatment is discharged into the inspection tank, and is recharged into the ground after passing the inspection, and is discharged into the sedimentation tank for re-treatment if it fails the inspection; In step (1), the groundwater extraction well system and the groundwater recharge well system are arranged at intervals; the extraction pipeline in the groundwater extraction well system is composed of several extraction wells connected in series, and the recharge pipeline in the groundwater recharge well system is composed of several recharge wells connected in series, and flow meters are installed on both the extraction pipeline and the recharge pipeline to record the flow rate and flow rate of the treatment process; when the groundwater extraction well system is extracting and the groundwater recharge well system is recharging, the circulation efficiency and treatment volume are adjusted by controlling the valves of the extraction pipeline and recharge pipeline in different areas, so as to control the treatment effect of groundwater in different areas.

2. The method for circulating ammonia nitrogen in groundwater according to claim 1, wherein: In step (2), when adjusting the pH of the water body, the pH of the wastewater entering the stripping equipment is adjusted by liquid alkali and maintained at 11.5-12.

3. The method for circulating ammonia and nitrogen in groundwater according to claim 1, wherein: In step (2), during the stripping treatment, a two-stage stripping tower connected in series is used, and the stripping tower is filled with a filler made of polypropylene. Groundwater is evenly sprinkled on the filler from the top of the stripping tower, forming water droplets flowing to the bottom of the stripping tower. At the same time, a centrifugal fan blows air into the bottom of the stripping tower to ensure full contact between air and water, and free ammonia escapes from the water and is carried away by the air.

4. The method for circulating ammonia nitrogen in groundwater according to claim 1, wherein: In step (3), after the gas-liquid separation, the waste gas generated by the first-stage stripping tower and the waste gas generated by the second-stage stripping tower enter the activated carbon adsorber for adsorption respectively. A centrifugal exhaust fan is installed at the other end of the activated carbon adsorber to extract the waste gas and discharge it through the chimney.

5. The method for circulating treatment of groundwater ammonia nitrogen according to claim 1, characterized in that: In step (4), during the electrochemical deep treatment, the wastewater is treated using a penetrating electrochemical device, and the chloride ions in the water are used to cause the electrodes to generate a large number of free radicals with strong oxidizing properties, thereby degrading the pollutants.

6. The method for circulating ammonia nitrogen in groundwater according to claim 1, characterized in that: In step (2) and step (4), the sedimentation tank, the intermediate tank, and the inspection tank are all equipped with an online monitoring device for nitrogen and oxygen concentration, an online monitoring device for pH, and an online monitoring device for chloride ion concentration to monitor the operating effect of the groundwater ammonia nitrogen circulation treatment.

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