A rare earth high ammonium wastewater treatment system and method

Abstract

The present invention belongs to the field of environmental protection, and relates to a rare earth high ammonium wastewater treatment system and method thereof. The system includes a catalytic electrolysis deammonification nitrogen device, a rare earth precipitation recovery device, a purification device and a sludge dehydration device; the catalytic electrolysis deammonification nitrogen device includes an electrolyzer, a degassing tank and a catalyst dosing device, and an alkali solution dosing device and a pipeline mixer are sequentially installed on the water inlet pipe of the electrolyzer along the water flow direction, and the outlet of the catalyst dosing device is connected to the inlet of the pipeline mixer, and the water outlet of the electrolyzer is connected to the water inlet of the degassing tank; the rare earth precipitation recovery device includes a sedimentation tank and a dehydration device, and the slag outlet of the sedimentation tank is connected to the inlet of the dehydration device; the purification device includes a pH adjustment tank, a coagulation tank, a coagulation aid tank, a sedimentation tank / flotation tank, and an intermediate water tank. The present invention can efficiently remove ammonia nitrogen and total phosphorus, recover rare earths, and after treatment, ammonia nitrogen ≤2mg / L, total nitrogen ≤2mg / L, total phosphorus ≤0.3mg / L, and other pollutant indicators meet the emission standards.

Description

Technical Field

[0001] The invention belongs to the field of environmental protection, and in particular relates to a rare earth high-ammonium wastewater treatment system and a method thereof. Background Art

[0002] Rare earth is a general term for 17 metal elements including lanthanide elements, scandium and yttrium in the periodic table. It is a valuable strategic resource. There are 250 kinds of rare earth ores in nature. my country is a country with abundant rare earth resources and a major producer of rare earth products. Rare earth mining should be carried out according to different types of ores. Typical examples are the Baotou cerium fluoride carbonate deposit and the ionic rare earth ores in the south. Ionic rare earth ores are the product of granite weathering and exist in the soil layer in an ionic state. The mining method is to soak the soil with ammonium sulfate and replace the ionic rare earth elements into the solution. There are three methods for the specific implementation of this mining method, namely heap leaching, pool leaching and in-situ leaching. The first two methods are now banned, and in-situ leaching has been promoted. In-situ leaching is to directly dig tunnels in the mine, fill them with ammonium sulfate solution, collect the mother liquor below, and then precipitate rare earth carbonate through ammonium bicarbonate. In-situ leaching is the main mining method for ionic rare earth ores. However, after rare earth mining is completed, a large amount of wastewater containing ammonium sulfate will continue to flow out, year after year, day after day, all year round. The concentration of ammonium sulfate in the outflowing wastewater is about 150-5000 mg / L. These wastewaters are directly discharged into the surrounding water bodies, which will cause the ammonia nitrogen in the local water environment to seriously exceed the standard. Therefore, rare earth ammonium-containing wastewater must be treated. At present, there are many methods for treating rare earth ammonium-containing wastewater, but there are not many successful cases. There are mainly physical methods, chemical methods, and biological methods. Among them, physical methods include reverse osmosis, distillation, soil irrigation and other treatment technologies; chemical methods include ion exchange, ammonia stripping, breakpoint chlorination, incineration, chemical precipitation, electrodialysis, electrochemistry and other treatment technologies; biological methods include algae cultivation, biological nitrification, immobilized biotechnology and other treatment technologies. The biological method of removing rare earth wastewater containing ammonium sulfate refers to the ammonia nitrogen in the wastewater, under the action of various microorganisms, through a series of reactions such as nitrification and denitrification, and finally forming nitrogen gas, thereby achieving the purpose of removing ammonia nitrogen. There are many biological denitrification processes, but the mechanisms are basically the same, and all require two stages: nitrification and denitrification. The nitrification reaction is the oxidation of ammonia nitrogen in wastewater into nitrite or nitrate by aerobic nitrifying bacteria under aerobic conditions. It includes two basic reaction steps: the reaction of converting ammonia nitrogen into nitrite with the participation of nitrite bacteria, and the reaction of converting nitrite into nitrate with the participation of nitrate bacteria. Among them, nitrite bacteria and nitrate bacteria are both autotrophic bacteria. They use the carbon source in the wastewater to obtain energy through redox reactions with NH3-N. The reaction equation is as follows:

[0003] Nitrosation: 2NH4 + +3O2→2NO2 - +2H2O+4H +

[0004] Nitrification: 2NO2 - +O2→2NO3 -

[0005] The suitable pH value for nitrifying bacteria is 8.0-8.4, and the optimal temperature is 35°C. The temperature has a great influence on nitrifying bacteria. When the temperature drops to 10°C, the nitrification reaction almost stops; DO concentration: 2-3 mg / L; BOD5 load: 0.06-0.1 kgBOD5 / (kgMLSS·d); sludge age is more than 3-5 days. Under anaerobic conditions, denitrifying bacteria (denitrifying bacteria) are used to reduce nitrite and nitrate to nitrogen gas and escape from the wastewater. Due to the action of facultative denitrifying bacteria (denitrifying bacteria), the process of reducing nitrate or nitrite produced in the nitrification process to N2 is called denitrification. The electron donors in the denitrification process are various organic substrates (carbon sources). Taking methanol as a carbon source as an example, the reaction formula is:

[0006] 6NO3 - +2CH3OH→6NO2 - +2CO2+4H2O

[0007] 6NO2 - +3CH3OH→3N2+3CO2+3H2O+6OH -

[0008] The suitable pH value for denitrifying bacteria is 6.5-8.0; the optimal temperature is 30℃. When the temperature is lower than 10℃, the denitrification rate decreases significantly, and when the temperature drops to 3℃, the denitrification will stop.

[0009] However, in addition to being mainly adapted to water bodies with relatively low ammonia nitrogen concentrations and appropriate carbon-nitrogen ratios, the biochemical nitrification and denitrification process also requires the consumption of a large amount of carbon sources. Since the high-ammonium wastewater produced during rare earth mining and rare earth processing contains almost no carbon source, if the biochemical method is used, all carbon sources need to be added externally. In addition, the ammonium ion concentration of high-ammonium wastewater from rare earth mining and rare earth is as high as 150-5000 mg / L. Therefore, in addition to the large biochemical pool, a large amount of carbon source needs to be added during operation, resulting in unacceptable production costs. Therefore, there is an urgent need for a rare earth wastewater treatment method with high efficiency, low investment and operation costs, and the ability to recycle rare earth resources in wastewater. Summary of the invention

[0010] The purpose of the present invention is to provide a new rare earth high ammonium wastewater treatment system and method for the defects of the existing rare earth high ammonium wastewater treatment process, such as large land occupation, large investment, poor effluent quality, substandard effluent ammonia nitrogen, and high operating cost. The rare earth high ammonium wastewater treatment system and method combine catalytic electrolytic ammonia nitrogen removal, rare earth precipitation recovery, physical and chemical purification and sludge dehydration, have a short process flow, small land occupation, small investment, high effluent water quality, low operating cost, strong adaptability to wastewater quality, and good sustained effect.

[0011] Specifically, the present invention provides a rare earth high ammonium wastewater treatment system, including a catalytic electrolytic deammoniation and nitrogen removal device, a rare earth precipitation recovery device, a physicochemical purification device and a sludge dehydration device;

[0012] The catalytic electrolysis deammoniation and nitrogen removal device comprises an electrolyzer, a degassing tank and a catalyst dosing device, an alkali dosing device and a pipeline mixer are sequentially installed on the water inlet pipe of the electrolyzer along the water flow direction, the outlet of the catalyst dosing device is connected to the inlet of the pipeline mixer, and the water outlet of the electrolyzer is connected to the water inlet of the degassing tank; the rare earth precipitation recovery device comprises a sedimentation tank and a dehydration device, the slag outlet of the sedimentation tank is connected to the inlet of the dehydration device; the water outlet of the degassing tank in the catalytic electrolysis deammoniation and nitrogen removal device is connected to the inlet of the alkali dosing device through a circulation pump on one side and connected to the water inlet of the sedimentation tank in the rare earth precipitation recovery device on the other side, The slag discharge port at the bottom of the degassing tank is connected to the water inlet of the sedimentation tank in the rare earth sedimentation recovery device, and the water outlets of the sedimentation tank and the dehydration device in the rare earth sedimentation recovery device are both connected to the water inlet of the pH regulating tank in the physicochemical purification device; or, the water outlets of the sedimentation tank and the dehydration device in the rare earth sedimentation recovery device are both connected to the water inlet pipe of the electrolyzer in the catalytic electrolytic deammoniation and nitrogen removal device, the water outlet of the degassing tank in the catalytic electrolytic deammoniation and nitrogen removal device is connected to the inlet of the alkali solution dosing device through a circulation pump on one side and connected to the water inlet of the pH regulating tank in the physicochemical purification device on the other side, and the slag discharge port at the bottom of the degassing tank is connected to the water inlet of the sedimentation tank in the rare earth recovery device;

[0013] The physicochemical purification device includes a pH regulating tank, a coagulation tank, a coagulation-aiding tank, a sedimentation tank / flotation tank, and an intermediate water tank. The water outlet of the pH regulating tank is connected to the water inlet of the coagulation tank, the water outlet of the coagulation-aiding tank is connected to the water inlet of the coagulation-aiding tank, the water outlet of the coagulation-aiding tank is connected to the water inlet of the sedimentation tank / flotation tank, and the water outlet of the sedimentation tank / flotation tank is connected to the water inlet of the intermediate water tank; the sludge dewatering device includes a sludge thickening tank, a physicochemical regulating tank and a dewatering machine. The inlet of the sludge thickening tank is connected to the sludge outlet of the sedimentation tank / flotation tank in the physicochemical purification device, the sludge outlet of the sludge thickening tank is connected to the inlet of the physicochemical regulating tank, the wastewater outlet of the sludge thickening tank is connected to the water inlet of the pH regulating tank in the physicochemical purification device, and the outlet of the physicochemical regulating tank is connected to the inlet of the dewatering machine.

[0014] Furthermore, the water inlet of the degassing tank in the catalytic electrolysis deammoniation and nitrogen removal device is connected to a water distributor located at the bottom of the degassing tank, and a scraper and a bubble scum collection tank are also provided on the top of the degassing tank. The scraper is used to scrape the bubbles on the liquid surface in the degassing tank into the bubble collection tank.

[0015] Furthermore, the pH adjusting tank, coagulation tank and coagulant aid tank of the physicochemical purification device are respectively provided with a pH adjusting agent dosing device, a coagulant dosing device and a coagulant aid dosing device; the pH adjusting agent dosing device includes a pH adjusting agent storage tank and a first dosing pump, the pH adjusting agent storage tank is connected to the pH adjusting tank and the first dosing pump is arranged on the connecting pipeline between the two; the coagulant dosing device includes a coagulant storage tank and a second dosing pump, the coagulant storage tank is connected to the coagulation tank and the second dosing pump is arranged on the connecting pipeline between the two; the coagulant aid dosing device includes a coagulant aid storage tank and a third dosing pump, the coagulant aid storage tank is connected to the coagulant aid tank and the third dosing pump is arranged on the connecting pipeline between the two.

[0016] Furthermore, the catalytic electrolysis deammoniation and nitrogen removal device also includes an electrode cleaning device, which includes a pickling solution storage tank and a pickling solution delivery pump. The outlet of the pickling solution storage tank is connected to the water outlet of the electrolyzer and the pickling solution delivery pump is arranged on the connecting pipeline between the two. The inlet of the pickling solution storage tank is connected to the water inlet of the electrolyzer.

[0017] Furthermore, the physicochemical purification device also includes a sludge return pump, the inlet of the sludge return pump is connected to the sludge outlet of the sedimentation tank / flotation tank, and the outlet of the sludge return pump is connected to the coagulation tank.

[0018] Furthermore, the sludge thickening tank in the sludge dewatering device is a gravity thickening tank, and the interior of the gravity thickening tank includes an upper clear liquid zone and a lower sludge thickening zone from top to bottom, the water outlet of the upper clear liquid zone is connected to the water inlet of the pH adjustment tank in the physicochemical purification device, the sludge outlet of the lower sludge thickening zone is connected to the inlet of the physicochemical adjustment tank, and the outlet of the physicochemical adjustment tank is connected to the inlet of the dewatering machine.

[0019] The present invention also provides a method for treating rare earth high-ammonium wastewater, which is carried out in the above-mentioned rare earth high-ammonium wastewater treatment system.

[0020] In a specific embodiment of the present invention, when the rare earth content in the rare earth high-ammonia wastewater to be treated is less than 500 mg / L, the method for treating rare earth high-ammonia wastewater comprises the following steps:

[0021] S11, catalytic electrolysis of ammonia nitrogen removal: the pH value of the rare earth high-ammonia wastewater to be treated is adjusted to 8.5-10 by using an alkali solution dosing device, and then mixed with the chloride ion catalyst from the catalyst dosing device in a pipeline mixer and introduced into an electrolyzer for catalytic electrolytic denitrification of ammonia nitrogen. The amount of the chloride ion catalyst is based on controlling the chloride ion concentration of the wastewater introduced into the electrolyzer to be 100-300 mg / L; the wastewater obtained after the catalytic electrolytic denitrification of ammonia nitrogen is introduced into a degassing tank for gas-liquid separation, and the supernatant obtained by the gas-liquid separation is adjusted to 8.5-10 after the pH value is adjusted to 100-300 mg / L after the chloride ion concentration is adjusted to 100-300 mg / L, and then pumped into the electrolyzer again for further catalytic electrolytic denitrification until the ammonia nitrogen and total nitrogen are qualified;

[0022] S12, rare earth recovery: after the catalytic electrolysis of ammonia and nitrogen is completed, the effluent from the degassing tank and the slag at the bottom of the degassing tank are transported to the sedimentation tank of the rare earth precipitation recovery device for sedimentation separation, the obtained supernatant is introduced into the pH adjustment tank of the physicochemical purification device, and the obtained precipitation product is introduced into the dehydration device of the rare earth precipitation recovery device for dehydration and rare earth recovery;

[0023] S13, physical and chemical purification: the supernatant obtained by sedimentation separation in step S12 is introduced into a pH adjustment tank to adjust its pH value to 8-9, then introduced into a coagulation tank and a coagulant is added and mixed evenly, the coagulant is selected from at least one of ferric chloride, polyferric, ferrous sulfate, aluminum sulfate and polyaluminum chloride, then introduced into a coagulant aid tank and polyacrylamide is added and mixed evenly, then introduced into a sedimentation tank or a flotation tank for solid-liquid separation, and a supernatant and sludge are obtained after the solid-liquid separation, and the sludge is introduced into a sludge thickening tank of a sludge dewatering device;

[0024] S14, sludge dewatering: the sludge residue obtained in step S13 is transported to the sludge thickening tank of the sludge dewatering device for gravity concentration to obtain the upper clarified liquid and the bottom concentrated sludge; the clarified liquid is returned to the pH regulating tank of the physicochemical purification device for further treatment, and the concentrated sludge is transported to the physicochemical regulating tank; a physicochemical regulator is added to the physicochemical regulating tank for physicochemical regulation, and the physicochemical regulator is selected from at least one of lime, ferric chloride and polyaluminium chloride, and the sludge after physicochemical regulation is then transported to the dewatering machine for dehydration.

[0025] In a specific embodiment of the present invention, when the rare earth content in the rare earth high-ammonia wastewater to be treated is greater than 500 mg / L, the method for treating rare earth high-ammonia wastewater comprises the following steps:

[0026] S21, rare earth recovery: transport the rare earth high ammonia wastewater to be treated to the sedimentation tank of the rare earth precipitation recovery device and adjust the pH value to 8.5-10 before sedimentation separation, introduce the obtained supernatant into the electrolyzer of the catalytic electrolysis deammoniation and nitrogen removal device, and introduce the obtained precipitation product into the dehydration device of the rare earth precipitation recovery device for dehydration and rare earth recovery;

[0027] S22, catalytic electrolysis of ammonia nitrogen removal: the supernatant from the rare earth precipitation recovery device and the chloride ion catalyst from the catalyst dosing device are mixed evenly in a pipeline mixer and then introduced into an electrolyzer for catalytic electrolysis of ammonia nitrogen removal. The amount of the chloride ion catalyst is based on controlling the chloride ion concentration of the wastewater introduced into the electrolyzer to be 100-300 mg / L. The wastewater obtained after the catalytic electrolysis of ammonia nitrogen removal is introduced into a degassing tank for gas-liquid separation. The supernatant obtained by the gas-liquid separation is adjusted to a pH value of 8.5-10 and a chloride ion concentration of 100-300 mg / L, and then pumped into the electrolyzer again for further catalytic electrolysis of nitrogen removal until the ammonia nitrogen and total nitrogen meet the standards.

[0028] S23, physical and chemical purification: after the catalytic electrolysis of ammonia nitrogen is completed, the effluent from the degassing tank is introduced into a pH adjustment tank to adjust its pH value to 8-9, and then introduced into a coagulation tank and a coagulant is added to mix evenly, the coagulant is selected from at least one of ferric chloride, polyferric, ferric sulfate, aluminum sulfate and polyaluminum chloride, and then introduced into a coagulant aid tank and polyacrylamide is added to mix evenly, and then introduced into a sedimentation tank or a flotation tank for solid-liquid separation, and a supernatant and sludge are obtained after the solid-liquid separation, and the sludge is introduced into a sludge thickening tank of a sludge dewatering device;

[0029] S24, sludge dewatering: the sludge residue obtained in step S23 is transported to the sludge thickening tank of the sludge dewatering device for gravity concentration to obtain the upper clarified liquid and the bottom concentrated sludge; the clarified liquid is returned to the pH regulating tank of the physicochemical purification device for further treatment, and the concentrated sludge is transported to the physicochemical regulating tank; a physicochemical regulator is added to the physicochemical regulating tank for physicochemical regulation, and the physicochemical regulator is selected from at least one of lime, ferric chloride and polyaluminium chloride, and the sludge after physicochemical regulation is then transported to the dewatering machine for dehydration.

[0030] Furthermore, the dosage of the coagulant is 30 to 120 g / m 3 .

[0031] Furthermore, the dosage of the coagulant aid is 0.1 to 1 g / m 3 .

[0032] Furthermore, the chloride ion catalyst is sodium hypochlorite and / or sodium chloride.

[0033] Furthermore, the working voltage of the catalytic electrolysis for deammoniation of nitrogen is 5 to 100 V and the current is 10 to 2000 A, and the residence time of the gas-liquid separation is 10 to 150 min.

[0034] Furthermore, the effluent indicators of the rare earth high-ammonia wastewater to be treated after treatment in each step are as follows: ammonia nitrogen ≤2 mg / L, total nitrogen ≤2.0 mg / L, total phosphorus ≤0.3 mg / L, and other indicators meet the emission standards.

[0035] Compared with the prior art, the present invention has the following obvious advantages:

[0036] (1) Rare earth resources are fully recycled and utilized

[0037] The current rare earth wastewater treatment technology not only has poor water quality after treatment, but also does not take a reasonable method to recover the rare earths in the wastewater. The present invention can recover about 100 to 1000 g / m 3 The rare earths in rare earth wastewater can be fully utilized, saving rare earth resources, reducing resource waste and alleviating the environmental pollution caused by rare earth development.

[0038] (2) High water quality, transforming wastewater into recyclable water resources

[0039] After the rare earth high-ammonium wastewater is treated by the recovery system and the recovery method provided by the present invention, not only all other indicators meet the indicators of Table 2 of the "Rare Earth Industry Pollutant Emission Standard" (GB26451-2011), but also the ammonia nitrogen is ≤2mg / L, the total nitrogen is ≤2mg / L, and the total phosphorus is ≤0.3mg / L. The rare earth wastewater has been converted into a water resource that can be recycled and discharged into natural water bodies, which can effectively increase the dissolved oxygen in the water body, effectively inhibit the growth of algae, and comprehensively improve and enhance the water quality. At the same time, it can be used as industrial and agricultural production and commercial water.

[0040] (3) Eradicating nitrogen and phosphorus pollution at the source

[0041] At present, the discharge standards of wastewater in Table 2 of the "Rare Earth Industry Pollutant Emission Standard" (GB26451-2011) implemented by existing wastewater plants are ammonia nitrogen ≤ 15 mg / L, total nitrogen ≤ 30 mg / L, and total phosphorus ≤ 1 mg / L. A large amount of nitrogen and phosphorus enter the water body with the discharge water of the wastewater treatment plant, causing a large amount of nitrogen enrichment in the water body. Therefore, the discharge water of the wastewater treatment plant is one of the main sources of nitrogen and phosphorus in rivers and lakes. After the rare earth high ammonium wastewater treatment system and method of the present invention are used to treat rare earth wastewater, the ammonia nitrogen of the water body is ≤ 2 mg / L, the total nitrogen is ≤ 2 mg / L, and the total phosphorus is ≤ 0.3 mg / L, which can completely eradicate the nitrogen and phosphorus pollution of the water body from the source.

[0042] (4) Simple process and easy operation

[0043] The system and method provided by the present invention are used to treat rare earth wastewater, which only includes four main processes: catalytic electrolysis to remove ammonia and nitrogen, precipitation to recover rare earths, physical and chemical purification, and sludge dehydration. The production process is simpler than the existing rare earth wastewater treatment production process, with fewer building structures and simpler operation.

[0044] (5) Save more than 90% of the land area

[0045] At present, when rare earth wastewater treatment plants built by activated sludge method at home and abroad treat wastewater, most of them have a retention time of more than 20 hours and occupy a large area. When the system and method provided by the present invention are used to treat rare earth wastewater, the retention time of the water body is only 1.0 to 2.0 hours, and the area occupied by the device is less than one-tenth of the existing traditional device, which occupies a small area and can save a lot of land resources.

[0046] (6) Low operating costs

[0047] The operating cost of treating rare earth wastewater using the system and method provided by the present invention is much lower than that of existing rare earth wastewater treatment plants, but the water quality is much higher, and the effluent is a water resource that can be recycled, so the operating cost is low.

[0048] (7) Short construction period

[0049] The rare earth wastewater treatment system provided by the present invention includes a catalytic electrolytic ammonia nitrogen removal device, a rare earth precipitation recovery device, a physicochemical purification device and a sludge dewatering device. These devices are all standardized devices, and the main equipment is produced in the factory. When these devices are used to build a wastewater treatment plant, it is only necessary to assemble these standardized devices in the wastewater treatment plant without the need to build a large number of structures. Therefore, the construction period of the wastewater treatment plant will be shortened by more than half compared with the construction period of a traditional plant, and the construction period is short. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a specific connection schematic diagram of the rare earth high-ammonium wastewater treatment system provided by the present invention.

[0051] Figure 2 It is a schematic diagram of the catalytic electrolysis ammonia nitrogen removal device provided by the present invention.

[0052] Figure 3 It is a schematic diagram of the rare earth precipitation recovery device provided by the present invention.

[0053] Figure 4 It is a specific schematic diagram of the physicochemical purification device provided by the present invention.

[0054] Figure 5 It is another specific schematic diagram of the physicochemical purification device provided by the present invention.

[0055] Figure 6 It is a schematic diagram of the sludge dewatering device provided by the present invention.

[0056] Figure numerals: 100-catalytic electrolysis deammonification and nitrogen removal device, 200-rare earth precipitation recovery device, 300-physical and chemical purification device, 400-sludge dehydration device, 110-electrolyzer, 120-DC power supply, 130-degassing tank, 131-water inlet, 132-water distributor, 134-slag discharge port, 135-circulation pump, 140-electrode cleaning device, 141-pickling solution storage tank, 142-pickling solution delivery pump, 150-catalyst dosing device, 151-catalyst solution storage tank, 152-catalyst solution delivery pump, 153-pipeline mixer, 154-alkali solution dosing device, 210-sedimentation tank, 220-dehydration device, 21 1-water inlet, 230-intermediate water tank, 240-thickening tank, 310, 310'-pH adjustment tank, 320, 320'-coagulation tank, 330, 330'-coagulation aid tank, 340-sedimentation tank, 340'-flotation tank, 350, 350'-intermediate water tank, 341-sludge outlet, 342-supernatant outlet, 344-sludge pump, 341'-sludge outlet, 342'-clean water outlet, 344'-sludge pump, 410-sludge thickening tank, 411-wastewater outlet, 412-concentrated sludge outlet, 420-physical and chemical adjustment tank, 430-dehydrator, 431-water outlet, 432-sludge outlet, 440-sludge tank. DETAILED DESCRIPTION

[0057] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0058] See also Figure 1 The rare earth high ammonium wastewater treatment system provided by the present invention includes: a catalytic electrolysis deammoniation and nitrogen removal device 100, a rare earth precipitation recovery device 200, a physicochemical purification device 300 and a sludge dehydration device 400.

[0059] The catalytic electrolysis ammonia nitrogen removal device 100 is used to remove ammonia nitrogen (ammonium ions) from rare earth wastewater. Figure 2In a specific embodiment, the catalytic electrolysis deammoniation nitrogen device 100 includes an electrolyzer 110, a DC power supply 120, a degassing tank 130, an electrode cleaning device 140 and a catalyst dosing device 150, wherein the DC power supply 120 is used to provide a working power supply to the electrolyzer 110, and an alkali solution dosing device 154 and a pipeline mixer 153 are sequentially installed on the water inlet pipe of the electrolyzer 110 along the water flow direction, and the outlet of the catalyst dosing device 150 is connected to the inlet of the pipeline mixer 153, and the water outlet of the electrolyzer 110 is connected to the water inlet 131 of the degassing tank 130. After the water outlet of the electrolyzer 110 passes through the water inlet 131, it is preferred that the water distributor 132 at the bottom of the degassing tank 130 is firstly entered. The catalyst dosing device 150 is used to add a chloride ion catalyst (sodium hypochlorite or sodium chloride) to supplement the chloride ions used as a catalyst. The catalyst dosing device 150 includes a catalyst solution storage tank 151 and a catalyst solution delivery pump 152. The outlet of the catalyst solution storage tank 151 is connected to the water inlet pipe of the electrolyzer 110 via the catalyst solution delivery pump 152 and is installed before the pipeline mixer 153 on the water inlet pipe of the electrolyzer 110. The operating voltage of the electrolyzer 110 can be 5 to 100 V, and the current density can be 10 to 150 mA / cm 2 More specifically, the catalyst dosing device 150 is used to add 6% to 12% sodium hypochlorite solution or 2% to 20% sodium chloride solution to the electrolyzer 110. Figure 2 As shown, the catalytic electrolysis deammoniation nitrogen device 100 preferably also includes an electrode cleaning device 140, and the electrode cleaning device 140 includes a pickling solution storage tank 141 and a pickling solution delivery pump 142, the outlet of the pickling solution storage tank 141 is connected to the water outlet of the electrolyzer 110 and the pickling solution delivery pump 142 is arranged on the connecting pipeline between the two, and the inlet of the pickling solution storage tank 141 is connected to the water inlet of the electrolyzer 110. When the electrode in the electrolyzer 110 is contaminated and scaled, and the electrolysis efficiency is reduced, the electrolyzer 110 is stopped, and the pickling solution delivery pump 142 is started to introduce the pickling solution in the pickling solution storage tank 141 into the electrolyzer 110 to remove the scale deposited on the electrode surface. Wherein, the pickling solution can be a 2% to 3% hydrochloric acid solution or a 4% to 5% citric acid solution.

[0060] The rare earth precipitation recovery device 200 is used to recover rare earth. Figure 3The rare earth precipitation recovery device 200 includes a sedimentation tank 210 and a dehydration device 220, and the slag outlet of the sedimentation tank 210 is connected to the inlet of the dehydration device 220. Among them, an intermediate water tank 230 is preferably provided at the water outlet of the sedimentation tank 210 for adjusting the water volume so that the system can run smoothly. A concentration tank 240 is preferably provided on the connecting pipeline between the slag outlet of the sedimentation tank 210 and the inlet of the dehydration device 220 for concentrating the sludge from the sedimentation tank 210 to increase the solid content. The slag outlet of the dehydration device 220 is connected to the rare earth collection tank.

[0061] In a specific embodiment, the outlet of the degassing tank 130 in the catalytic electrolysis deammoniation nitrogen device 100 is connected to the inlet of the alkali solution dosing device 154 via the circulating pump 135 on one side and to the water inlet of the sedimentation tank 210 in the rare earth precipitation recovery device 200 on the other side. The slag discharge port at the bottom of the degassing tank 130 is connected to the water inlet of the sedimentation tank 210 in the rare earth precipitation recovery device. The outlets of the sedimentation tank 210 and the dehydration device 220 in the rare earth precipitation recovery device are both connected to the water inlet of the pH adjustment tank 310 in the physicochemical purification device 300. At this time, the water inlet pipe of the electrolyzer in the catalytic electrolysis deammoniation nitrogen device 100 is connected to the wastewater source, and the wastewater is first electrolytically deammonified and then rare earths are recovered. It is particularly suitable for treating rare earth high-ammonia wastewater with a rare earth content of less than 500 mg / L. In addition, preferably, the outlet water of the electrolyzer 110 first enters the water distributor 132 at the bottom of the degassing tank 130 after passing through the water inlet 131, and then enters the water distributor in the middle of the sedimentation tank 210 through the water inlet 211 installed at the upper part of the degassing tank 130. A slag discharge port 134 is provided at the bottom of the degassing tank 130, and the slag discharge port 134 is connected to the water inlet 211 of the rare earth precipitation recovery device 200.

[0062] In a specific embodiment, the water outlets of the sedimentation tank 210 and the dehydration device 220 in the rare earth precipitation recovery device 200 are both connected to the water inlet pipe of the electrolyzer 110 in the catalytic electrolysis deammoniation nitrogen device 100. The water outlet of the degassing tank 130 in the catalytic electrolysis deammoniation nitrogen device 100 is connected to the inlet of the alkali solution dosing device 154 via the circulating pump 135 on one side and to the water inlet of the pH adjustment tank in the physicochemical purification device 300 on the other side. The slag discharge port at the bottom of the degassing tank 130 is connected to the water inlet of the sedimentation tank 200 in the rare earth recovery device. At this time, the water inlet 211 of the sedimentation tank 210 in the rare earth precipitation recovery device 200 is connected to the wastewater source, and the wastewater is first rare earth recovered and then electrolytic deammoniation nitrogen is carried out, which is particularly suitable for treating rare earth high-ammonia wastewater with a rare earth content greater than 500 mg / L.

[0063] The physicochemical purification device 300 is used to remove SS, chromaticity, water-insoluble COD, BOD5 and total phosphorus in wastewater. The physicochemical purification device 300 can be a flotation purification device or a coagulation sedimentation device.

[0064] In a preferred embodiment, the physicochemical purification device 300 is a coagulation sedimentation device, and the coagulation sedimentation device is selected from a high-efficiency sedimentation device, a magnetic coagulation device, and a super magnetic coagulation sedimentation device. Figure 4 The coagulation and sedimentation device includes a pH regulating tank 310, a coagulation tank 320, a coagulation-aiding tank 330, a sedimentation tank 340 and an intermediate water tank 350; the water outlet of the pH regulating tank 310 is connected to the water inlet of the coagulation tank 320, the water outlet of the coagulation tank 320 is connected to the water inlet of the coagulation-aiding tank 330, the water outlet of the coagulation-aiding tank 330 is connected to the water inlet of the sedimentation tank 340, the top of the sedimentation tank 340 is provided with a supernatant outlet 342 and the bottom is provided with a sludge outlet 341, the supernatant outlet 342 is connected to the water inlet of the intermediate water tank 350, and the sludge outlet 341 is connected to the inlet of the sludge thickening tank 410 in the sludge dewatering device 400 via a sludge pump 344. In addition, the pH regulating tank 310, the coagulation tank 320 and the coagulation-aiding tank 330 are preferably provided with a stirrer.

[0065] In another preferred embodiment, the physicochemical purification device 300 is an air flotation purification device, and the air flotation purification is dissolved air flotation or shallow air flotation. Figure 5 The flotation purification device includes a pH adjusting tank 310', a coagulation tank 320', a coagulant aid tank 330', a flotation tank 340' and an intermediate water tank 350'; the water outlet of the pH adjusting tank 310' is connected to the water inlet of the coagulation tank 320', the water outlet of the coagulation tank 320' is connected to the water inlet of the coagulant aid tank 330', the water outlet of the coagulant aid tank 330' is connected to the water inlet of the flotation tank 340', the flotation tank 340' is provided with a sludge outlet 341' at the top and a clean water outlet 342' at the bottom, the clean water outlet 342' is connected to the water inlet of the intermediate water tank 350', and the sludge outlet 341' is connected to the inlet of the sludge thickening tank 410 in the sludge dewatering device 400 via a sludge pump 344'. In addition, the pH adjustment tank 310', the coagulation tank 320', and the coagulation aid tank 330' are preferably provided with a stirrer.

[0066] The pH adjustment tank, coagulation tank and coagulant aid tank of the physicochemical purification device 300 are respectively provided with a pH adjuster dosing device, a coagulant dosing device and a coagulant aid dosing device. The pH adjuster dosing device comprises a pH adjuster storage tank and a first dosing pump, wherein the pH adjuster is stored in the pH adjuster storage tank, and the pH adjuster in the pH adjuster storage tank is added to the pH adjustment tank through the first dosing pump. The coagulant dosing device comprises a coagulant storage tank and a second dosing pump, wherein the coagulant storage tank stores at least one of ferric chloride, polyferric, ferrous sulfate, aluminum sulfate and polyaluminum chloride, and the coagulant in the coagulant storage tank is added to the coagulation tank through the second dosing pump. The coagulant aid dosing device comprises a coagulant storage tank and a third dosing pump, wherein the coagulant storage tank stores a coagulant aid polyacrylamide (PAM), and the coagulant aid is added to the coagulant aid tank through the third dosing pump. It should be noted that the above “first”, “second” and “third” are only used to distinguish different dosing pumps for the convenience of description and have no other special meanings.

[0067] In a preferred embodiment, the physicochemical purification device 300 also includes a sludge return pump for returning part of the sludge in the sedimentation tank 340 or the flotation tank 340' to the coagulation tank, the inlet of the sludge return pump is connected to the sludge outlet of the sedimentation tank 340 or the flotation tank 340', and the outlet of the sludge return is connected to the coagulation tank.

[0068] See also Figure 6 The sludge dewatering device 400 includes a sludge pump, a sludge thickening tank 410, a physicochemical regulating tank 420, a dewatering machine 430 and a sludge tank 440; the inlet of the sludge pump is connected to the sludge outlet of the sedimentation tank 340 or the flotation tank 340' in the physicochemical purification device 300; the outlet of the sludge pump is connected to the inlet of the sludge thickening tank 410, the upper part of the sludge thickening tank 410 is provided with a wastewater outlet 411, and the bottom of the sludge thickening tank 410 is provided with a concentrated sludge outlet 4 12; the wastewater outlet 411 is connected to the water inlet of the pH regulating tank in the physicochemical purification device 300, the concentrated sludge outlet 412 is connected to the inlet of the physicochemical regulating tank 420, the outlet of the physicochemical regulating tank 420 is connected to the inlet of the dewatering machine 430, the water outlet 431 of the dewatering machine 430 is discharged if it meets the standards, and if it does not meet the standards, it is returned to the physicochemical purification device 300 for further treatment, and the mud outlet 432 of the dewatering machine 430 is connected to the sludge tank 440.

[0069] In a preferred embodiment, the sludge thickening tank 410 is a gravity thickening tank, and the sludge outlets of the sedimentation tank / flotation tank in the physicochemical purification device are respectively connected to the inlet of the gravity thickening tank 410. The interior of the gravity thickening tank 410 includes an upper clear liquid area and a lower sludge thickening area from top to bottom. The outlet of the upper clear liquid area is connected to the inlet of the pH adjustment tank in the physicochemical purification device, and the outlet of the lower sludge thickening area is connected to the inlet of the physicochemical adjustment tank 420. The outlet of the physicochemical adjustment tank 420 is connected to the inlet of the dewatering machine 430.

[0070] The method for treating rare earth high ammonium wastewater provided by the present invention is carried out in the above-mentioned rare earth high ammonium wastewater treatment system, and specifically includes four steps of catalytic electrolytic deammoniation and nitrogen removal, rare earth recovery, physical and chemical purification, and sludge dehydration. Among them, the order of the two steps of catalytic electrolytic deammoniation and nitrogen removal and rare earth recovery can be adjusted according to the rare earth content in the rare earth high ammonia wastewater to be treated. When the rare earth content in the rare earth high ammonia wastewater to be treated is less than 500 mg / L, catalytic electrolytic deammoniation and nitrogen removal are first performed before rare earth recovery; when the rare earth content in the rare earth high ammonia wastewater to be treated is greater than 500 mg / L, rare earth recovery is first performed before catalytic electrolytic deammoniation and nitrogen removal.

[0071] (1) In the catalytic electrolysis deammoniation process, the chloride ion catalyst can be sodium hypochlorite or sodium chloride. The amount of the chloride ion catalyst is based on controlling the chloride ion concentration of the wastewater introduced into the electrolyzer to be 100-300 mg / L. The conditions for the catalytic electrolysis deammoniation preferably include an operating voltage of 5-100 V and a current density of 10-150 mA / cm 2 The time for the wastewater obtained after the catalytic electrolysis of ammonia nitrogen removal to be introduced into the degassing tank for gas-liquid separation is preferably 10 to 150 minutes, more preferably 10 to 60 minutes.

[0072] The hypochlorous acid generated by the electrolyzer 110 during operation reacts with the ammonium ions in the rare earth wastewater to be converted into nitrogen. The sodium hypochlorite generated by the electrolyzer 110 reacts with the ammonium ions in the wastewater, and a large amount of nitrogen is released in the degassing tank 130, generating a large amount of bubbles, and the scum is collected by the scraper into the scum collection tank; the effluent after catalytic electrolysis denitrification is injected into the rare earth precipitation recovery device 200 or the physical and chemical purification device 300.

[0073] The catalytic electrolysis ammonia nitrogen removal device 100 is used to remove ammonium ions in wastewater, and the main indicators of the effluent are: pH 8-9, chroma ≤4, NH3-N (ammonia nitrogen) ≤2.0 mg / L, and total nitrogen ≤2.0 mg / L.

[0074] The electrolysis time in the electrolyzer 110 is preferably 30 to 210 seconds. During the electrolysis, a 10% to 12% sodium hypochlorite solution or a 2% to 6% sodium chloride solution is added through a catalyst adding device.

[0075] In the catalytic electrolysis process of removing ammonia nitrogen, sodium hypochlorite produced by electrolysis reacts with ammonia nitrogen to generate nitrogen gas and sodium chloride, and sodium chloride is electrolyzed to generate sodium hypochlorite again, which is circulated back and forth and used repeatedly, and the role played by sodium hypochlorite is a catalyst.

[0076] NaOCl+H2O→HOCl+NaOH

[0077] NH3+HOCl→NH2Cl+H2O(monochloramine)

[0078] NH2Cl+HOCl→NHCl2+H2O(dichloramine)

[0079] 2NHCl2+NaOCl→N2↑+3NaCl+H2O (main denitrification reaction 1)

[0080] Main reaction:

[0081] 2NH3+3NaOCl→N2↑+3NaCl+3H2O

[0082] (2) Rare earth recovery: The sedimentation tank of the rare earth sedimentation recovery device performs rare earth sedimentation separation, and the bottom sediment enters the dehydration device for dehydration to recover the rare earth. According to the concentration difference of rare earth in the rare earth wastewater, 100 to 1000g of crude rare earth can be recovered per ton of rare earth wastewater.

[0083] Generally, rare earths can be precipitated from the wastewater by adjusting the pH value of the wastewater to 8.5-10 and then letting it stand. However, in order to make the precipitation of rare earths more complete and shorten the recovery period, it is preferred to add ammonium bicarbonate to the wastewater and then let it stand to recover the rare earths.

[0084] (3) Physicochemical purification: The effluent from catalytic electrolysis for ammonia nitrogen removal or rare earth recovery is introduced into the pH adjustment tank of the physicochemical purification device, and alkaline substances such as sodium hydroxide or sodium carbonate are added and stirred continuously at a stirring speed of 80 to 200 r / min and a stirring time of 1 to 2 min to adjust the pH value of the wastewater to 8 to 9. The adjusted wastewater is then sent to the coagulation tank, and coagulant is added through the coagulation dosing device and stirred continuously at a stirring speed of 100 to 200 r / min and a coagulation reaction time of 3 to 5 min. The effluent after adding the coagulant is input into the coagulation aid tank, and PAM is added through the coagulation dosing device and stirred continuously at a stirring speed of 20 to 50 r / min and a stirring time of 1 to 2 min. The effluent from the coagulation aid tank is input into the sedimentation tank or the flotation tank for solid-liquid separation, and the wastewater clear liquid obtained by physicochemical purification is input into the intermediate water tank. In this step, it is necessary to determine whether the amount of sediment formed in the coagulation tank is sufficient. If it is insufficient, the sludge return pump is turned on, and part of the sludge is returned from the sedimentation tank or flotation tank to the coagulation tank to promote the formation of flocculent sediment.

[0085] During the coagulation, coagulation aid, and sedimentation / flotation process, phosphate and hydrogen phosphate in the wastewater react with trivalent aluminum ions or trivalent iron ions to generate iron phosphate precipitates, thereby removing total phosphorus from the wastewater;

[0086] 3Al 3+ +2PO4 3- =Al3(PO4)2↓

[0087] In addition, since the large amount of flocculent precipitation generated has a huge specific surface area and carries an electric charge, it can adsorb organic matter in the wastewater and remove the color and COD in the wastewater. After physical and chemical purification treatment, 80-95% of SS in the water can be removed, making the SS of the water ≤50mg / L, and 90-95% of the total phosphorus in the water can be removed, making the total phosphorus of the water ≤0.2mg / L.

[0088] (4) Sludge dehydration: The sludge or scum produced by the physical and chemical purification in step (3) is transported to a sludge thickening tank for gravity concentration to form a clarified liquid at the top and concentrated sludge at the bottom; the clarified liquid is transported back to the pH adjustment tank of the physical and chemical purification device, and the concentrated sludge is transported to a physical and chemical adjustment tank; a physical and chemical regulator is added to the physical and chemical adjustment tank for physical and chemical regulation, and then the sludge is transported to a dehydrator for dehydration. The physical and chemical regulator is selected from at least one of lime, ferric chloride and polyaluminium chloride.

[0089] The effluent indicators of the rare earth high-ammonia wastewater to be treated after the steps of catalytic electrolysis of ammonia nitrogen, rare earth recovery, physicochemical purification and sludge dehydration are: ammonia nitrogen ≤2 mg / L, total nitrogen ≤2.0 mg / L, total phosphorus ≤0.3 mg / L, and other indicators comply with the emission standards of Table 2 of the "Rare Earth Industry Pollutant Emission Standard" (GB26451-2011).

[0090] The present invention will be described in detail below with reference to embodiments.

[0091] Example 1

[0092] See also Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 6 The rare earth high ammonium wastewater treatment system provided in this embodiment includes a catalytic electrolysis deammoniation and nitrogen removal device 100, a rare earth precipitation recovery device 200, a physicochemical purification device 300 and a sludge dehydration device 400.

[0093] See also Figure 2The catalytic electrolysis deammoniation nitrogen device 100 includes an electrolyzer 110, a DC power supply 120, a degassing tank 130, an electrode cleaning device 140 and a catalyst dosing device 150; the geometric dimensions of the electrolyzer 110 are a circular tube of 315×2500 (mm), and an electrode group is installed in the tube; the water inlet of the electrolyzer 110 is connected to the wastewater source, and the water outlet of the electrolyzer 110 is connected to the water inlet of the degassing tank 130; an alkali solution dosing device 154 and a pipeline mixer 153 are sequentially installed on the water inlet pipe of the electrolyzer 110 along the water flow direction; the geometric dimensions of the degassing tank 130 are a circular barrel of 1200×2300 (mm), and the water outlet is 400 (mm) from the top of the barrel, The degassing tank 130 is connected to the aeration tank through a Φ100 pipeline. The outlet of the degassing tank 130 is connected to the inlet of the alkali solution dosing device 154 through a circulation pump 135 and is connected to the water inlet 211 of the sedimentation tank 210 in the rare earth precipitation recovery device 200 through another way. The slag discharge port at the bottom of the degassing tank 130 is connected to the water inlet 211 of the sedimentation tank 210 in the rare earth precipitation recovery device 200. The electrode cleaning device 140 includes a pickling solution storage tank 141 and a pickling solution delivery pump 142. The outlet of the pickling solution storage tank 141 is connected to the outlet of the electrolyzer 110 and the pickling solution delivery pump 142 is arranged on the connecting pipeline between the two. The inlet of the pickling solution storage tank 141 is connected to the water inlet of the electrolyzer 110. The pickling solution adopts a 2% to 3% hydrochloric acid solution or a 4% to 5% citric acid solution. The catalyst dosing device 150 includes a chloride ion catalyst solution storage tank 151 and a delivery pump 152 . The outlet of the chloride ion catalyst solution storage tank 151 is connected to the inlet of a pipeline mixer 153 under the action of the delivery pump 152 .

[0094] See also Figure 3 The rare earth precipitation recovery device 200 includes a sedimentation tank 210, a dewatering device 220, an intermediate water tank 230 and a concentrating tank 240. The water inlet 211 of the sedimentation tank 210 is connected to the water outlet of the degassing tank 130 and the slag discharge port 134 at the bottom. The water outlet of the sedimentation tank 210 is connected to the water inlet of the intermediate water tank 230. The water outlet of the intermediate water tank 230 is connected to the water inlet of the physicochemical purification device 300. The slag outlet of the sedimentation tank 210 is connected to the entrance of the concentrating tank 240. The concentrated sludge outlet of the concentrating tank 240 is connected to the inlet of the dewatering device 220. The water outlet of the dewatering device 220 is connected to the water inlet of the physicochemical purification device 300. The mud outlet of the dewatering device 220 is connected to the outside to discharge the sludge.

[0095] See also Figure 4The physicochemical purification device 300 is a coagulation and sedimentation device. The coagulation and sedimentation device includes a pH regulating tank 310, a coagulation tank 320, a coagulation-aiding tank 330, a sedimentation tank 340 and an intermediate water tank 350; the water outlet of the pH regulating tank 310 is connected to the water inlet of the coagulation tank 320, the water outlet of the coagulation tank 320 is connected to the water inlet of the coagulation-aiding tank 330, the water outlet of the coagulation-aiding tank 330 is connected to the water inlet of the sedimentation tank 340, the top of the sedimentation tank 340 is provided with a supernatant outlet 342 and the bottom is provided with a sludge outlet 341, the supernatant outlet 342 is connected to the water inlet of the intermediate water tank 350, and the sludge outlet 341 is connected to the inlet of the sludge thickening tank 410 in the sludge dewatering device 400 via a sludge pump 344. In addition, a stirrer is provided in the pH regulating tank 310, the coagulation tank 320 and the coagulation-aiding tank 330.

[0096] See also Figure 6 The sludge dewatering device 400 includes a sludge pump, a sludge thickening tank 410, a physicochemical adjustment tank 420, a dewatering machine 430 and a sludge tank 440; the inlet of the sludge pump is connected to the sludge outlet of the sedimentation tank 340 in the physicochemical purification device; the outlet of the sludge pump is connected to the inlet of the sludge thickening tank 410, the upper part of the sludge thickening tank 410 is provided with a wastewater outlet 411, and the bottom of the sludge thickening tank 410 is provided with a concentrated sludge outlet 412; The wastewater outlet 411 is connected to the water inlet of the pH adjustment tank in the physicochemical purification device 300, the concentrated sludge outlet 412 is connected to the inlet of the physicochemical adjustment tank 420, the outlet of the physicochemical adjustment tank 420 is connected to the dewatering machine 430, and the water outlet 431 of the dewatering machine 430 is discharged if the water meets the standards, and if it does not meet the standards, it is returned to the physicochemical purification device 300 for further treatment, and the mud outlet 432 of the dewatering machine 430 is connected to the sludge tank 440.

[0097] In this embodiment, the inlet water index and outlet water compliance index of the rare earth high-ammonia wastewater to be treated are shown in Table 1.

[0098] Table 1

[0099] Serial number project Influent index (mg / L) Effluent standard index (mg / L) Removal rate (%) 1 COD 20 20 0 2 BOD 10 6 40 3 SS 200 10 95 4 Total nitrogen (N) 300 2 99.33 5 Ammonia nitrogen (as N) 298 1.5 99.50 6 Total phosphorus (P) 0.5 0.3 40 7 Chroma(dilution factor) 10 2 80 8 pH 6.5 6～9 - 9 Rare earth content 350 0.2 99.94

[0100] The rare earth high ammonium wastewater treatment method used in this embodiment includes four steps in sequence: catalytic electrolysis to remove ammonia nitrogen, precipitation to recover rare earth, physical and chemical purification, and sludge dehydration. Among them, the physical and chemical purification adopts a coagulation sedimentation (high-density sedimentation) process. Specifically:

[0101] The alkali solution dosing device 154 is used to add a 10% sodium hydroxide solution to the rare earth high ammonia wastewater to be treated to adjust its pH value to 9.2, and pump it into the pipeline mixer 153. At the same time, the delivery pump 152 in the catalyst dosing device 150 is started, and a 12% sodium hypochlorite solution is added to the pipeline mixer 153 to increase the chloride ion concentration in the wastewater to 120 mg / L. After the wastewater and the chloride ion catalyst are evenly mixed in the pipeline mixer 153, they are pumped into the electrolyzer 110 for catalytic electrolytic denitrification. The working voltage of the electrolyzer 110 is 36.5 V and the current density is 11 mA / cm 2 The clean water after electrolysis enters the degassing tank 130 for gas-liquid separation, and the bubbles on the top are scraped into the bubble collection tank by the scraper. The lower clear liquid is adjusted to 9.2 by pH value and 120 mg / L by chloride ion concentration, and then pumped into the electrolyzer 110 for further electrolysis and purification until the ammonia nitrogen and total nitrogen are qualified (ammonia nitrogen ≤ 2 mg / L, total nitrogen ≤ 2.0 mg / L). The effluent indicators of catalytic electrolysis of ammonia nitrogen are shown in Table 2.

[0102] Table 2

[0103]

[0104] After the electrolytic removal of ammonia nitrogen and passing the test, the wastewater enters the sedimentation tank 210 of the rare earth precipitation recovery device 200 to precipitate and recover rare earths, and then is introduced into the physicochemical purification device 300 for physicochemical purification. The pH value is first adjusted to 8.5, and then a 10% polyaluminum (PAC) solution coagulant is added, and the addition amount is 120 mg / L (in terms of PAC). After coagulation reaction at a speed of 100 rpm, 1 mg / L of coagulant PAM is added and reacted at a speed of 20 rpm. After entering the sedimentation tank for separation, the influent for precipitation recovery of rare earths and the effluent for physicochemical purification are shown in Table 3. The removal rate in Table 3 is calculated based on the raw water (i.e., the influent for catalytic electrolytic removal of ammonia nitrogen). After the sludge treated by the physicochemical purification device 300 is dehydrated by the wastewater dehydration device 400 to obtain dehydrated cement blocks.

[0105] Table 3

[0106]

[0107] From the results of Table 2 and Table 3, it can be seen that the catalytic electrolysis deammoniation nitrogen device 100 has a good removal effect on ammonia nitrogen (ammonium ions) and total nitrogen, but will produce a large number of small brown-red particles; the wastewater after catalytic electrolysis deammoniation nitrogen enters the rare earth precipitation recovery device 200 for precipitation, and the rare earth precipitate in the sedimentation tank 210 is recovered and dehydrated by the dehydration device 220 to obtain a coarse rare earth precipitate 2015g / m 3The supernatant of the sedimentation tank 210 enters the coagulation sedimentation device 300 for coagulation sedimentation, and the total phosphorus and SS contents can be significantly reduced. The effluent indicators of the rare earth wastewater treated by the system and method of this embodiment meet the water quality standards of Table 2 of the Rare Earth Industry Pollutant Emission Standard (GB26451-2011), except that the total nitrogen is less than 2 mg / L and the ammonia nitrogen is less than 1.5 mg / L.

[0108] Example 2

[0109] See also Figure 1 , Figure 2 , Figure 3 , Figure 5 and Figure 6 The rare earth high ammonium wastewater treatment system provided in this embodiment includes a catalytic electrolysis deammoniation and nitrogen removal device 100, a rare earth precipitation recovery device 200, a physicochemical purification device 300 and a sludge dehydration device 400.

[0110] See also Figure 2 The catalytic electrolysis deammoniation nitrogen device 100 includes an electrolyzer 110, a DC power supply 120, a degassing tank 130, an electrode cleaning device 140 and a catalyst dosing device 150; the geometric size of the electrolyzer 110 is a circular tube of 315×2500 (mm), and an electrode group is installed in the tube; the water outlet of the electrolyzer 110 is connected to the water inlet of the degassing tank 130; the water inlet pipe of the electrolyzer 110 is sequentially installed with an alkali solution dosing device 154 and a pipeline mixer 153 along the water flow direction; the geometric size of the degassing tank 130 is a barrel of 1200×2300 (mm), and the outlet is 400 (mm) from the top of the barrel, and the water is discharged through a Φ100 pipeline The outlet of the degassing tank 130 is connected to the inlet of the alkali solution dosing device 154 through the circulation pump 135 and the inlet of the pH regulating tank in the physicochemical purification device 300. The slag discharge port at the bottom of the degassing tank 130 is connected to the inlet 211 of the sedimentation tank 210 in the rare earth precipitation recovery device 200. The electrode cleaning device 140 includes a pickling solution storage tank 141 and a pickling solution delivery pump 142. The outlet of the pickling solution storage tank 141 is connected to the outlet of the electrolyzer 110 and the pickling solution delivery pump 142 is arranged on the connecting pipeline between the two. The inlet of the pickling solution storage tank 141 is connected to the inlet of the electrolyzer 110. The pickling solution adopts a 2% to 3% hydrochloric acid solution or a 4% to 5% citric acid solution. The catalyst dosing device 150 includes a chloride ion catalyst solution storage tank 151 and a delivery pump 152 . The outlet of the chloride ion catalyst solution storage tank 151 is connected to the inlet of a pipeline mixer 153 under the action of the delivery pump 152 .

[0111] See also Figure 3The rare earth precipitation recovery device 200 includes a sedimentation tank 210, a dehydration device 220, an intermediate water tank 230 and a concentrating tank 240. The water inlet 211 of the sedimentation tank is connected to a wastewater source, the water outlet of the sedimentation tank 210 is connected to the water inlet of the intermediate water tank 230, the water outlet of the intermediate water tank 230 is connected to the water inlet pipe of the electrolyzer 110 in the catalytic electrolysis deammoniation nitrogen device 100, the slag outlet of the sedimentation tank 210 is connected to the inlet of the concentrating tank 240, the concentrated sludge outlet of the concentrating tank 240 is connected to the inlet of the dehydration device 220, the water outlet of the dehydration device 220 is connected to the water inlet pipe of the electrolyzer in the catalytic electrolysis deammoniation nitrogen device, and the mud outlet of the dehydration device 220 is connected to the outside to discharge the sludge.

[0112] See also Figure 5 The physicochemical purification device 300 is an air flotation purification device. The flotation purification device includes a pH adjusting tank 310', a coagulation tank 320', a coagulant tank 330', a flotation tank 340' and an intermediate water tank 350'; the water outlet of the pH adjusting tank 310' is connected to the water inlet of the coagulation tank 320', the water outlet of the coagulation tank 320' is connected to the water inlet of the coagulant tank 330', the water outlet of the coagulant tank 330' is connected to the water inlet of the flotation tank 340', the flotation tank 340' is provided with a sludge outlet 341' at the top and a clean water outlet 342' at the bottom, the clean water outlet 342' is connected to the water inlet of the intermediate water tank 350', the sludge outlet 341' is connected to the inlet of the sludge thickening tank 410 in the sludge dewatering device 400 via a sludge pump 344'; the pH adjusting tank 310', the coagulation tank 320' and the coagulant tank 330' are all provided with agitators.

[0113] See also Figure 6 The sludge dewatering device 400 includes a sludge pump, a sludge thickening tank 410, a physicochemical adjustment tank 420, a dewatering machine 430 and a sludge tank 440; the inlet of the sludge pump is connected to the sludge outlet of the sedimentation tank 340 in the physicochemical purification device; the outlet of the sludge pump is connected to the inlet of the sludge thickening tank 410, the upper part of the sludge thickening tank 410 is provided with a wastewater outlet 411, and the bottom of the sludge thickening tank 410 is provided with a concentrated sludge outlet 412; The wastewater outlet 411 is connected to the water inlet of the pH adjustment tank in the physicochemical purification device 300, the concentrated sludge outlet 412 is connected to the inlet of the physicochemical adjustment tank 420, the outlet of the physicochemical adjustment tank 420 is connected to the dewatering machine 430, and the water outlet 431 of the dewatering machine 430 is discharged if the water meets the standards, and if it does not meet the standards, it is returned to the physicochemical purification device 300 for further treatment, and the mud outlet 432 of the dewatering machine 430 is connected to the sludge tank 440.

[0114] In this embodiment, the inlet water index and outlet water compliance index of the rare earth high-ammonia wastewater to be treated are shown in Table 4.

[0115] Table 4

[0116] Serial number project Influent index (mg / L) Effluent standard index (mg / L) Removal rate (%) 1 COD 30 20 33.30 2 BOD 10 6 40 3 SS 30 10 66.67 4 Total nitrogen (N) 412 2 99.51 5 Ammonia nitrogen (as N) 410 1.5 99.63 6 Total phosphorus (P) 0.7 0.3 57.14 7 Chroma(dilution factor) 10 2 80 8 pH 6.5 6～9 - 9 Rare earth content 620 0.2 99.96

[0117] The rare earth high ammonium wastewater treatment method adopted in this embodiment includes four steps in sequence: precipitation recovery of rare earth, catalytic electrolysis of ammonia nitrogen, physicochemical purification, and sludge dehydration. Among them, the physicochemical purification adopts an air flotation purification process, and the sludge dehydration adopts a centrifugal dehydration process. Specifically:

[0118] A 10% sodium hydroxide solution was added to the rare earth high ammonia wastewater to be treated to adjust its pH value to 9.5, and then an ammonium bicarbonate solution was added. After the reaction was carried out at a speed of 100 rpm, the solution was introduced into the sedimentation tank 210 of the rare earth precipitation recovery device 200 for sedimentation separation to obtain a crude rare earth precipitate of 2530 g / m 3 The water quality after rare earth recovery is shown in Table 5.

[0119] Table 5

[0120]

[0121] The rare earth wastewater treated by the rare earth precipitation recovery device enters the catalytic electrolysis ammonia nitrogen removal device 100 for treatment, and at the same time, the delivery pump 152 in the catalyst dosing device 150 is started, and a 20% sodium chloride solution is added to the pipeline mixer 253 to increase the chloride ion concentration in the wastewater to 300 mg / L. After the wastewater and the chloride ion catalyst are evenly mixed in the pipeline mixer 153, they are pumped into the electrolyzer 110 for ion catalytic electrolysis denitrification. The working voltage of the electrolyzer 110 is 100 V, and the current density is 150 mA / cm 2 The clean water after electrolysis enters the degassing tank 130 for gas-liquid separation, and the bubbles on the top are scraped into the bubble collection tank by the scraper. The lower clear liquid is adjusted to 9.5 by pH value and 300 mg / L by chloride ion concentration, and then pumped into the electrolyzer 110 for further electrolysis purification until the ammonia nitrogen and total nitrogen are qualified (ammonia nitrogen ≤ 2 mg / L, total nitrogen ≤ 2.0 mg / L). The effluent index of catalytic electrolysis for ammonia nitrogen removal is shown in Table 6. The removal rate in Table 3 is calculated based on the raw water (i.e., the influent water for precipitation recovery of rare earth).

[0122] Table 6

[0123]

[0124] The wastewater after the electrolytic removal of ammonia nitrogen and the qualified test is introduced into the physicochemical purification device 300 for physicochemical purification. The pH value is first adjusted to 9, and then a 10% polyaluminum (PAC) solution coagulant is added, and the addition amount is 120 mg / L (in terms of PAC). After the coagulation reaction at a speed of 100 rpm, 1 mg / L of coagulant PAM is added and the reaction is carried out at a speed of 20 rpm. After entering the sedimentation tank for separation, the influent of rare earth recovery by precipitation and the effluent of physicochemical purification are shown in Table 7. The removal rate in Table 7 is calculated based on the raw water (i.e. the influent of rare earth recovery by precipitation). The sludge treated by the physicochemical purification device 300 is dehydrated by the wastewater dehydration device 400 to obtain dehydrated cement blocks.

[0125] Table 7

[0126]

[0127] From the results in Tables 6 and 7, it can be seen that after the rare earth high ammonium wastewater is treated by the rare earth precipitation recovery device 200, 2530 g / m 3 The crude rare earth precipitate is removed, and the wastewater after rare earth recovery is treated with catalytic electrolytic denitrification and flotation purification. The effluent ammonia nitrogen is less than 1.5 mg / L, and the total nitrogen is less than 2 mg / L. Except for other major pollutant indicators, it fully meets the water quality standards in Table 2 of the "Rare Earth Industry Pollutant Emission Standard" (GB26451-2011).

[0128] Example 3

[0129] The rare earth high-ammonia wastewater treatment system used in this embodiment is the same as that in Embodiment 1. In this embodiment, the inlet index and outlet index of the rare earth high-ammonia wastewater to be treated are shown in Table 8.

[0130] Table 8

[0131] Serial number project Influent index (mg / L) Effluent standard index (mg / L) Removal rate (%) 1 COD 20 20 0 2 BOD 10 6 40 3 SS 150 10 93.33 4 Total nitrogen (N) 265 2 99.24 5 Ammonia nitrogen (as N) 264.5 1.5 99.43 6 Total phosphorus (P) 0.7 0.3 57.14 7 Chroma(dilution factor) 10 2 80 8 pH 6.5 6～9 - 9 Rare earth content 310 0.2 99.94

[0132] The rare earth high ammonium wastewater treatment method used in this embodiment includes four steps in sequence: catalytic electrolysis to remove ammonia nitrogen, precipitation to recover rare earth, physical and chemical purification, and sludge dehydration. Among them, the physical and chemical purification adopts a coagulation sedimentation (high-density sedimentation) process. Specifically:

[0133] The alkali solution dosing device 154 is used to add a 10% sodium hydroxide solution to the rare earth high ammonia wastewater to be treated to adjust its pH value to 9.5, and pump it into the pipeline mixer 153. At the same time, the delivery pump 152 in the catalyst dosing device 150 is started, and a 12% sodium hypochlorite solution is added to the pipeline mixer 153 to increase the chloride ion concentration in the wastewater to 150 mg / L. After the wastewater and the chloride ion catalyst are evenly mixed in the pipeline mixer 153, they are pumped into the electrolyzer 110 for catalytic electrolytic denitrification. The working voltage of the electrolyzer 110 is 5V and the current density is 10mA / cm2 The clean water after electrolysis enters the degassing tank 130 for gas-liquid separation, and the bubbles on the top are scraped into the bubble collection tank by the scraper. The lower clear liquid is adjusted to 9.5 by pH value and 150 mg / L by chloride ion concentration, and then pumped into the electrolyzer 110 for further electrolysis purification until the ammonia nitrogen and total nitrogen are qualified (ammonia nitrogen ≤ 2 mg / L, total nitrogen ≤ 2.0 mg / L). The effluent indicators of catalytic electrolysis of ammonia nitrogen are shown in Table 9.

[0134] Table 9

[0135]

[0136] After the electrolytic denitrification is qualified, the wastewater enters the sedimentation tank 210 of the rare earth precipitation recovery device 200 to precipitate and recover rare earths, and then is introduced into the physicochemical purification device 300 for physicochemical purification. The pH value is first adjusted to 8, and then a 10% polyaluminum (PAC) solution coagulant is added, and the addition amount is 120 mg / L (in terms of PAC). After coagulation reaction at a speed of 100 rpm, 1 mg / L of coagulant PAM is added. After reaction at a speed of 20 rpm, it enters the sedimentation tank for separation. The influent water for precipitating and recovering rare earths and the effluent water for physicochemical purification are shown in Table 10. The removal rate in Table 10 is calculated based on the raw water (i.e., the influent water for catalytic electrolytic deammoniation and nitrogen removal). After the sludge treated by the physicochemical purification device 300 is dehydrated by the wastewater dehydration device 400 to obtain dehydrated cement blocks.

[0137] Table 10

[0138]

[0139] From the results of Tables 9 and 10, it can be seen that the catalytic electrolysis deammoniation nitrogen device 100 has a good removal effect on ammonia nitrogen (ammonium ions) and total nitrogen, but will produce a large number of small brown-red particles; the wastewater after catalytic electrolysis deammoniation nitrogen enters the rare earth precipitation recovery device 200 for precipitation, and the rare earth precipitate in the sedimentation tank 210 is recovered and dehydrated by the dehydration device 220 to obtain a coarse rare earth precipitate of 811g / m 3 The supernatant of the sedimentation tank 210 enters the coagulation sedimentation device 300 for coagulation sedimentation, and the total phosphorus and SS contents can be significantly reduced. The effluent indicators of the rare earth wastewater treated by the system and method of this embodiment meet the water quality standards of Table 2 of the Rare Earth Industry Pollutant Emission Standard (GB26451-2011), except that the total nitrogen is less than 2 mg / L and the ammonia nitrogen is less than 1.5 mg / L.

[0140] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A rare earth high ammonium wastewater treatment system, characterized in that: The invention comprises a catalytic electrolysis deamination and nitrogen removal device, a rare earth precipitation recovery device, a physicochemical purification device and a sludge dehydration device; the catalytic electrolysis deamination and nitrogen removal device comprises an electrolyzer, a DC power supply, a degassing tank and a catalyst dosing device, an alkali solution dosing device and a pipeline mixer are sequentially installed on the water inlet pipe of the electrolyzer along the water flow direction, the outlet of the catalyst dosing device is connected to the inlet of the pipeline mixer, and the water outlet of the electrolyzer is connected to the water inlet of the degassing tank; the rare earth precipitation recovery device comprises a sedimentation tank and a dehydration device, and the slag outlet of the sedimentation tank is connected to the dehydration device. The water outlet of the degassing tank in the catalytic electrolytic deammoniation and nitrogen removal device is connected to the inlet of the alkali solution dosing device through a circulating pump on one side and connected to the water inlet of the sedimentation tank in the rare earth precipitation recovery device on the other side. The slag discharge port at the bottom of the degassing tank is connected to the water inlet of the sedimentation tank in the rare earth precipitation recovery device. The water outlets of the sedimentation tank and the dehydration device in the rare earth precipitation recovery device are both connected to the water inlet of the pH regulating tank in the physicochemical purification device; or, the water outlets of the sedimentation tank and the dehydration device in the rare earth precipitation recovery device are both connected to the water inlet of the pH regulating tank in the catalytic electrolytic deammoniation and nitrogen removal device. The catalytic electrolysis deammoniation and nitrogen removal device is connected to the water inlet pipe of the electrolyzer, the water outlet of the degassing tank in the catalytic electrolysis deammonification and nitrogen removal device is connected to the inlet of the alkali solution dosing device through a circulation pump on one side and connected to the water inlet of the pH regulating tank in the physicochemical purification device on the other side, the slag discharge port at the bottom of the degassing tank is connected to the water inlet of the sedimentation tank in the rare earth recovery device; the physicochemical purification device includes a pH regulating tank, a coagulation tank, a coagulation-aiding tank, a sedimentation tank / flotation tank, and an intermediate water tank, the water outlet of the pH regulating tank is connected to the water inlet of the coagulation tank, the water outlet of the coagulation tank is connected to the water inlet of the coagulation-aiding tank, and the The water outlet of the coagulation aid tank is connected to the water inlet of the sedimentation tank / flotation tank, and the water outlet of the sedimentation tank / flotation tank is connected to the water inlet of the intermediate water tank; the sludge dewatering device includes a sludge thickening tank, a physicochemical adjusting tank and a dewatering machine, the inlet of the sludge thickening tank is connected to the sludge outlet of the sedimentation tank / flotation tank in the physicochemical purification device, the sludge outlet of the sludge thickening tank is connected to the inlet of the physicochemical adjusting tank, the wastewater outlet of the sludge thickening tank is connected to the water inlet of the pH adjusting tank in the physicochemical purification device, and the outlet of the physicochemical adjusting tank is connected to the inlet of the dewatering machine.

2. The rare earth high ammonium wastewater treatment system according to claim 1, characterized in that: The water inlet of the degassing tank in the catalytic electrolysis deammoniation and nitrogen removal device is connected to a water distributor located at the bottom of the degassing tank. A scraper and a bubble scum collecting tank are also provided on the top of the degassing tank. The scraper is used to scrape the bubbles on the liquid surface in the degassing tank into the bubble collecting tank.

3. The rare earth high ammonium wastewater treatment system according to claim 1, characterized in that: The pH adjusting tank, coagulation tank and coagulant aid tank of the physicochemical purification device are respectively provided with a pH adjusting agent dosing device, a coagulant dosing device and a coagulant aid dosing device; the pH adjusting agent dosing device comprises a pH adjusting agent storage tank and a first dosing pump, the pH adjusting agent storage tank is connected to the pH adjusting tank and the first dosing pump is arranged on the connecting pipeline between the two; the coagulant dosing device comprises a coagulant storage tank and a second dosing pump, the coagulant storage tank is connected to the coagulation tank and the second dosing pump is arranged on the connecting pipeline between the two; the coagulant aid dosing device comprises a coagulant aid storage tank and a third dosing pump, the coagulant aid storage tank is connected to the coagulant aid tank and the third dosing pump is arranged on the connecting pipeline between the two.

4. The rare earth high ammonium wastewater treatment system according to claim 1, characterized in that: The catalytic electrolysis deammoniation and nitrogen removal device also includes an electrode cleaning device, which includes a pickling solution storage tank and a pickling solution delivery pump. The outlet of the pickling solution storage tank is connected to the water outlet of the electrolyzer and the pickling solution delivery pump is arranged on the connecting pipeline between the two. The inlet of the pickling solution storage tank is connected to the water inlet of the electrolyzer.

5. The rare earth high ammonium wastewater treatment system according to claim 1, characterized in that: The physicochemical purification device also includes a sludge return pump, the inlet of the sludge return pump is connected to the sludge outlet of the sedimentation tank / flotation tank, and the outlet of the sludge return pump is connected to the coagulation tank.

6. The rare earth high ammonium wastewater treatment system according to claim 1, characterized in that: The sludge thickening tank in the sludge dewatering device is a gravity thickening tank, and the interior of the gravity thickening tank includes an upper clear liquid area and a lower sludge thickening area from top to bottom. The water outlet of the upper clear liquid area is connected to the water inlet of the pH adjustment tank in the physicochemical purification device, and the sludge outlet of the lower sludge thickening area is connected to the inlet of the physicochemical adjustment tank, and the outlet of the physicochemical adjustment tank is connected to the inlet of the dewatering machine.

7. A method for treating rare earth high ammonium wastewater, characterized in that: The method is carried out in the rare earth high-ammonium wastewater treatment system described in any one of claims 1 to 6.

8. The method for treating rare earth high ammonium wastewater according to claim 7, characterized in that: When the rare earth content in the rare earth high-ammonium wastewater to be treated is below 500 mg / L, the method comprises the following steps: S11, catalytic electrolytic deammoniation and nitrogen removal: an alkali solution dosing device is used to adjust the pH value of the rare earth high-ammonium wastewater to be treated to 8.5-10, and then the alkali solution is mixed with the chloride ion catalyst from the catalyst dosing device in a pipeline mixer and then introduced into an electrolyzer for catalytic electrolytic deammoniation and nitrogen removal. The amount of the chloride ion catalyst is based on controlling the chloride ion concentration of the wastewater introduced into the electrolyzer to be 100-300 mg / L; the wastewater obtained after the catalytic electrolytic deammoniation and nitrogen removal is introduced into a degassing tank for gas-liquid separation, and the supernatant obtained by the gas-liquid separation is adjusted to 8.5-10 with a pH value and a chloride ion concentration of 100-300 mg / L, and then pumped into the electrolyzer again for further catalytic electrolytic denitrification until the ammonia nitrogen and total nitrogen are qualified; S12, rare earth recovery: after the catalytic electrolysis of ammonia and nitrogen is completed, the effluent from the degassing tank and the slag at the bottom of the degassing tank are transported to the sedimentation tank of the rare earth precipitation recovery device for sedimentation separation, the obtained supernatant is introduced into the pH adjustment tank of the physicochemical purification device, and the obtained precipitation product is introduced into the dehydration device of the rare earth precipitation recovery device for dehydration and recovery of rare earth; S13, physicochemical purification: the supernatant obtained by sedimentation separation in step S12 is introduced into the pH adjustment tank to adjust its pH value to 8-9, and then introduced into the coagulation tank and added with a coagulant to mix evenly, the coagulant is selected from at least one of ferric chloride, polyferric, ferric sulfate, aluminum sulfate and polyaluminum chloride, and then introduced into the coagulant aid tank and added with polyacrylamide to mix evenly, and then introduced into the sedimentation tank or the flotation tank for solid-liquid separation, and the supernatant and sludge are obtained after the solid-liquid separation, and the sludge is introduced into the sludge thickening tank of the sludge dehydration device; S14, sludge dewatering: the sludge residue obtained in step S13 is transported to the sludge thickening tank of the sludge dewatering device for gravity concentration to obtain the upper clarified liquid and the bottom concentrated sludge; the clarified liquid is returned to the pH regulating tank of the physicochemical purification device for further treatment, and the concentrated sludge is transported to the physicochemical regulating tank; a physicochemical regulator is added to the physicochemical regulating tank for physicochemical regulation, and the physicochemical regulator is selected from at least one of lime, ferric chloride and polyaluminium chloride, and the sludge after physicochemical regulation is then transported to the dewatering machine for dehydration.

9. The method for treating rare earth high ammonium wastewater according to claim 7, characterized in that: When the rare earth content in the rare earth high-ammonium wastewater to be treated is greater than 500 mg / L, the method comprises the following steps: S21, rare earth recovery: transporting the rare earth high-ammonium wastewater to be treated to a sedimentation tank of a rare earth precipitation recovery device and adjusting its pH value to 8.5-10 for sedimentation separation, introducing the obtained supernatant into an electrolyzer of a catalytic electrolysis deammoniation and nitrogen removal device, and introducing the obtained precipitation product into a dehydration device of a rare earth precipitation recovery device for dehydration and rare earth recovery; S22, catalytic electrolysis of ammonia nitrogen removal: the supernatant from the rare earth precipitation recovery device and the chloride ion catalyst from the catalyst dosing device are mixed evenly in a pipeline mixer and then introduced into an electrolyzer for catalytic electrolysis of ammonia nitrogen removal. The amount of the chloride ion catalyst is based on controlling the chloride ion concentration of the wastewater introduced into the electrolyzer to be 100-300 mg / L. The wastewater obtained after the catalytic electrolysis of ammonia nitrogen removal is introduced into a degassing tank for gas-liquid separation. The supernatant obtained by the gas-liquid separation is adjusted to a pH value of 8.5-10 and a chloride ion concentration of 100-300 mg / L, and then pumped into the electrolyzer again for further catalytic electrolysis of nitrogen removal until the ammonia nitrogen and total nitrogen meet the standards. S23, physical and chemical purification: after the catalytic electrolysis of ammonia nitrogen is completed, the effluent from the degassing tank is introduced into a pH adjustment tank to adjust its pH value to 8-9, and then introduced into a coagulation tank and a coagulant is added to mix evenly, the coagulant is selected from at least one of ferric chloride, polyferric, ferric sulfate, aluminum sulfate and polyaluminum chloride, and then introduced into a coagulant aid tank and polyacrylamide is added to mix evenly, and then introduced into a sedimentation tank or a flotation tank for solid-liquid separation, and a supernatant and sludge are obtained after the solid-liquid separation, and the sludge is introduced into a sludge thickening tank of a sludge dewatering device; S24, sludge dewatering: the sludge residue obtained in step S23 is transported to the sludge thickening tank of the sludge dewatering device for gravity concentration to obtain the upper clarified liquid and the bottom concentrated sludge; the clarified liquid is returned to the pH regulating tank of the physicochemical purification device for further treatment, and the concentrated sludge is transported to the physicochemical regulating tank; a physicochemical regulator is added to the physicochemical regulating tank for physicochemical regulation, and the physicochemical regulator is selected from at least one of lime, ferric chloride and polyaluminium chloride, and the sludge after physicochemical regulation is then transported to the dewatering machine for dehydration.

10. The method for treating rare earth high ammonium wastewater according to claim 8 or 9, characterized in that: The dosage of the coagulant is 30 to 120 g / m 3 The amount of polyacrylamide used is 0.1 to 1 g / m 3 ; The chloride ion catalyst is sodium hypochlorite and / or sodium chloride; the working voltage of the catalytic electrolysis deammoniation nitrogen is 5 to 100 V and the current density is 10 to 150 mA / cm 2 The residence time of the gas-liquid separation is 10 to 150 minutes; the effluent indicators of the rare earth high-ammonium wastewater to be treated after each step of treatment are as follows: ammonia nitrogen ≤ 2 mg / L, total nitrogen ≤ 2.0 mg / L, total phosphorus ≤ 0.3 mg / L, and other indicators meet the emission standards.

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