Treatment system for iron phosphate wastewater

Abstract

The utility model relates to the technical field of wastewater treatment, in particular to an iron phosphate wastewater treatment system. The utility model provides a treatment system for iron phosphate wastewater. The treatment system comprises a first filtering unit, a deamination membrane device, a mixing reactor, a sedimentation tank and a second filtering unit which are connected in sequence, and the second filter unit is connected with the deamination membrane device. The ferric phosphate wastewater treatment system provided by the utility model can be used for recovering ammonia nitrogen in ferric phosphate wastewater, and is low in operation cost; the wastewater treated by the deamination membrane device is recycled and returned to the deamination membrane device, so that the use amount of ammonia water is reduced, and sulfuric acid does not need to be added, thereby avoiding the influence of ammonium sulfate salt generated by the reaction of the added ammonia water and sulfuric acid on the subsequent treatment effects of the reverse osmosis device and the MVR evaporator.

Description

Technical Field

[0001] The utility model relates to the technical field of wastewater treatment, in particular to a treatment system for iron phosphate wastewater. Background Art

[0002] Iron phosphate is the positive electrode material for preparing new energy batteries. Its chemical formula is FePO4. It is mainly used in lithium-ion batteries and has the advantages of good compatibility, high energy density, long cycle life, high temperature performance and good safety performance.

[0003] Industrial wastewater is generated during the production process of ferric phosphate. This type of wastewater has a high ammonia nitrogen content and also contains metal impurities, sulfuric acid ions, phosphate ions and suspended solids. If the wastewater is not treated and discharged directly, it will not only cause waste of resources but also pollute the environment.

[0004] The ammonia pretreatment process for ferric phosphate wastewater is as follows: the pH of the wastewater is adjusted by ammonia water, and the phosphate salts in the wastewater are used to precipitate the metal salt impurities in the water. A large amount of ammonia water is added during this process, and sulfuric acid is subsequently added to adjust the pH to make the wastewater neutral; after the wastewater reaches neutrality, it enters the RO system for pure water desalination and concentration, and then enters the MVR system for evaporation and crystallization.

[0005] The disadvantage of this process is that sulfuric acid is added to make the wastewater neutral. The reaction of sulfuric acid and ammonia water will form ammonium sulfate, which affects the treatment efficiency of the subsequent RO system and MVR system.

[0006] In view of this, the present utility model is proposed. Utility Model Content

[0007] The purpose of the utility model is to provide a treatment system for ferric phosphate wastewater, which reduces the amount of ammonia water and sulfuric acid used in the ammonia pretreatment process of ferric phosphate wastewater, and avoids the influence of the increase of salts such as ammonium sulfate caused by the addition of acid and alkali on the treatment effect of subsequent reverse osmosis device and MVR evaporator.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0009] The utility model provides a treatment system for iron phosphate wastewater, comprising a first filtering unit, a deammoniation membrane device, a mixing reactor, a sedimentation tank and a second filtering unit which are connected in sequence;

[0010] The second filtering unit is connected to the ammonia removal membrane device.

[0011] Compared with the prior art, the beneficial effects of the present invention are:

[0012] 1. The ferric phosphate wastewater treatment system of the present invention can recover ammonia nitrogen in the ferric phosphate wastewater with high recovery rate, high efficiency and low operating cost.

[0013] 2. The ferric phosphate wastewater treatment system of the present invention uses a deamination membrane device to absorb ammonia nitrogen using the wastewater at the front and back ends of the deamination membrane device, thereby reducing the amount of ammonia water used and eliminating the need to add sulfuric acid, thereby avoiding the impact of ammonium sulfate salts generated by the reaction of ammonia water and sulfuric acid on the treatment effects of subsequent reverse osmosis devices and MVR evaporators. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 This is a schematic diagram of the iron phosphate wastewater treatment system of the present invention.

[0016] Reference numerals:

[0017] 1- regulating tank; 11- lifting pump;

[0018] 2-Security filter; 3-Ammonia removal membrane device;

[0019] 4-mixing reactor; 5-inclined plate sedimentation tank;

[0020] 61-Ultrafiltration booster pump; 62-Multi-media filter;

[0021] 63-Ultrafiltration device; 7-Reverse osmosis device;

[0022] 8-MVR evaporator. DETAILED DESCRIPTION

[0023] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but those skilled in the art will understand that the embodiments described below are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0024] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0025] Refer to the following Figure 1 , describing the iron phosphate wastewater treatment system provided by some embodiments of the present invention.

[0026] The embodiment of the present utility model provides a treatment system for iron phosphate wastewater, comprising a first filtration unit, an ammonia removal membrane device 3, a mixing reactor 4, a sedimentation tank and a second filtration unit connected in sequence;

[0027] The second filtration unit is connected to the ammonia removal membrane device 3 .

[0028] The ferric phosphate wastewater treatment system provided by the utility model is a ferric phosphate wastewater ammonia nitrogen recovery system. The treatment system has a high recovery rate of ammonia nitrogen in the ferric phosphate wastewater, high treatment efficiency and low operating cost.

[0029] The ferric phosphate wastewater treatment system of the present invention is provided with a deamination membrane device 3, and utilizes the wastewater at the front end and the wastewater at the back end of the deamination membrane to adsorb ammonia nitrogen. The wastewater treated by the deamination membrane device 3 is recycled and returned to the deamination membrane device 3, thereby reducing the amount of ammonia water used and eliminating the need to add sulfuric acid, thereby avoiding the reaction of adding ammonia water and sulfuric acid to form ammonium sulfate salt, which affects the treatment effect of the subsequent reverse osmosis device 7 and the MVR evaporator 8.

[0030] Ferric phosphate wastewater contains metal impurities, sulfate ions, phosphate ions and suspended solids; the pH of ferric phosphate wastewater is 2 to 2.5.

[0031] In the treatment system of ferric phosphate wastewater of the present invention, when in operation, the ferric phosphate wastewater enters the first filter unit for filtration and then enters the deamination membrane device 3, the mixing reactor 4, the sedimentation tank and the second filter unit in sequence before returning to the deamination membrane device 3.

[0032] In some embodiments, the ammonia removal membrane device 3 is provided with an acid solution inlet, an acid solution outlet, an alkali solution inlet and an alkali solution outlet;

[0033] The first filter unit is connected to the acid solution inlet of the deammoniation membrane device 3;

[0034] The acid liquid outlet of the deammonification membrane device 3 is connected to the mixing reactor 4;

[0035] The second filtering device is connected to the alkaline solution water inlet of the deammoniation membrane device 3.

[0036] In some embodiments, an ammonia removal membrane is provided in the ammonia removal membrane device 3 .

[0037] The working principle of the ammonia removal membrane is: ammonia water spontaneously hydrolyzes in an aqueous solution to form ammonia gas, and ammonia gas also dissolves in the aqueous solution to form ammonia water. This reaction is a reversible reaction, and its chemical formula is: When the temperature of the solution is greater than 30°C and the pH is alkaline, the reaction trend of the ammonia water in the solution is to hydrolyze ammonia gas, which is then absorbed by acidic wastewater to remove ammonia nitrogen in the solution.

[0038] When the deamination membrane device 3 is in operation, the iron phosphate wastewater filtered by the first filter unit enters the deamination membrane device 3 from the acid solution inlet, flows through the outer filaments of the deamination membrane, and acts as acid to absorb ammonia nitrogen in the wastewater returned to the deamination membrane device 3 before flowing out from the acid solution outlet; the iron phosphate wastewater filtered by the second filter unit enters the deamination membrane device 3 from the alkali solution inlet, flows through the inner filaments of the deamination membrane, and the hydrolyzed ammonia nitrogen is absorbed by the wastewater entering the deamination membrane device 3 from the acid solution inlet and flows out from the alkali solution outlet.

[0039] In some embodiments, the acid solution inlet of the deammoniation membrane device 3 is used to introduce the iron phosphate wastewater filtered by the first filtration unit, and the pH value of the wastewater is 2 to 2.5.

[0040] In some embodiments, the pH of the wastewater at the acid solution outlet of the deammoniation membrane device 3 is 3 to 3.5.

[0041] In some embodiments, the flow ratio of the acid solution inlet to the alkali solution inlet of the deammoniation membrane device 3 is (0.9-1):1.

[0042] When absorbing ammonia nitrogen, the pH value of the solution increases, causing metal ion precipitation, which will block the membrane pores of the deammonification membrane. By controlling the pH of the wastewater at the acid outlet, and then adjusting the flow rate, controlling the flow rate, and reducing the residence time of the wastewater in the membrane, the problem of metal ion precipitation can be effectively controlled.

[0043] In some embodiments, the ferric phosphate wastewater treatment system further includes a regulating tank 1 , the outlet of the regulating tank 1 is connected to the first filtration unit; the regulating tank 1 is used to store the ferric phosphate wastewater.

[0044] In some embodiments, the regulating tank 1 is connected to the first filtration unit via a lift pump 11 .

[0045] In some embodiments, the first filter unit includes a security filter 2 .

[0046] In some embodiments, the security filter 2 is used to filter the iron phosphate wastewater, and the content of suspended solids (ss) in the filtered iron phosphate wastewater is less than or equal to 300 mg / L.

[0047] The iron phosphate wastewater is filtered before entering the deamination membrane device 3, which can remove the suspended solids in the wastewater and avoid clogging of the deamination membrane pores after entering the deamination membrane device 3, thereby protecting the deamination membrane.

[0048] In some embodiments, the mixing reactor 4 is provided with an ammonia aqueous solution inlet.

[0049] An ammonia inlet is provided in the mixing reactor 4, through which ammonia is added to adjust the pH of the wastewater in the mixing reactor 4 to 8-9. In the mixing reactor 4, the P element in the iron phosphate wastewater is used to form phosphate, and the metal impurities in the water are coagulated and precipitated, and then the water enters the sedimentation tank for mud and water diversion.

[0050] In some embodiments, the sedimentation tank comprises an inclined plate sedimentation tank 5 .

[0051] In some embodiments, the second filtration unit includes an ultrafiltration booster pump 61, a multi-media filter 62, and an ultrafiltration device 63 connected in sequence;

[0052] The ultrafiltration booster pump 61 is connected to the sedimentation tank;

[0053] The ultrafiltration device 63 is connected to the alkali solution inlet of the deamination membrane device 3 .

[0054] After the wastewater flowing out of the acid outlet of the deamination membrane device 3 is added with ammonia water for coagulation and precipitation, the wastewater contains a large amount of suspended solids. The wastewater is filtered through the multi-media filter 62 and the ultrafiltration equipment 63 to remove the suspended solids and reduce the content of suspended solids in the wastewater to within 5 mg / L, thereby protecting the deamination membrane.

[0055] The ultrafiltration device 63 is connected to the alkali solution inlet of the deamination membrane device 3. The temperature of the iron phosphate wastewater after filtering by the ultrafiltration device 63 is controlled at 30-40°C, and then enters the deamination membrane device 3, flows through the inner filaments of the deamination membrane, and flows out through the alkali solution outlet. Its pH value is reduced to 6.5-7.5, and the ammonia nitrogen hydrolyzed during this period is absorbed.

[0056] In some embodiments, the ferric phosphate wastewater treatment system further comprises a reverse osmosis (RO) device 7 and an MVR evaporator 8 connected in sequence;

[0057] The reverse osmosis device 7 is connected to the alkaline solution outlet of the deamination membrane device 3.

[0058] During operation, the wastewater flowing out of the alkali solution outlet of the deammoniation membrane device 3 enters the reverse osmosis (RO) device 7 for treatment to obtain production pure water and concentrated liquid, and the concentrated liquid enters the MVR evaporator 8 for evaporation and crystallization.

[0059] In some embodiments, the ferric phosphate wastewater treatment system further includes a ferric phosphate wastewater pipeline; the outlet of the ferric phosphate wastewater pipeline is connected to the regulating tank 1.

[0060] In some embodiments, the process of treating ferric phosphate wastewater using the ferric phosphate wastewater treatment system of the present invention is as follows:

[0061] The ferric phosphate wastewater in the ferric phosphate wastewater pipeline flows into the regulating tank 1, enters the security filter 2 for filtration through the lifting pump 11, and the concentration of suspended solids in the wastewater is reduced to less than 300 mg / L, and the pH is 2-2.5; then it enters the deamination membrane device 3 from the acid inlet, flows through the outer wire of the deamination membrane, and after ammonia nitrogen adsorption is performed on the wastewater entering the deamination membrane device 3 from the alkali solution inlet, it flows out from the acid outlet. The pH of the wastewater flowing out of the acid outlet is 3-3.5; then it enters the mixing reactor 4, and ammonia is added to the mixing reactor 4. The wastewater is purified by the alkali water inlet, and the pH value of the wastewater is adjusted to 8-9, and the metal impurities in the water are coagulated and precipitated. The wastewater then enters the inclined plate sedimentation tank 5 for mud and water diversion, and then passes through the ultrafiltration booster pump 61, the multi-media filter 62 and the ultrafiltration device 63 in sequence to reduce the content of suspended solids in the wastewater to less than 5 mg / L. The wastewater then enters the deammonification membrane device 3 from the alkali solution inlet, and the ammonia nitrogen in the wastewater is absorbed and flows out from the alkali solution outlet. The pH value of the wastewater flowing out from the alkali solution outlet is 6.5-7.5. The wastewater finally enters the reverse osmosis (RO) device 7 and the MVR evaporator 8 in sequence.

[0062] When the ferric phosphate wastewater treatment system is in operation, the pH value of the solution entering from the alkali solution inlet of the deammonification membrane device 3 is 8-9, and the pH value of the solution entering from the acid solution inlet is 2-2.5. Ammonia nitrogen exchange is performed, and the pH value of the solution entering from the acid solution inlet increases and flows out from the acid solution outlet. In the later treatment process, the ammonia intake is reduced when the pH value is adjusted, and there is no need to add sulfuric acid to adjust the pH of the solution to 7, which reduces the intake of sulfate ions and ammonium ions, and the salt content in the water quality is relatively reduced, which indirectly reduces the burden on the RO and MVR systems, and improves the water production rate of the RO system and the evaporation capacity of the MVR system.

[0063] Example 1

[0064] See also Figure 1The ferric phosphate wastewater treatment system provided in this embodiment includes: a ferric phosphate wastewater pipeline, a regulating tank 1, a booster pump 11, a security filter 2, a deammonification membrane device 3, a mixing reactor 4, an inclined plate sedimentation tank 5, an ultrafiltration booster pump 61, a multi-media filter 62, an ultrafiltration device 63, a reverse osmosis device 7 and an MVR evaporator 8;

[0065] The ammonia removal membrane device 3 is provided with an acid solution inlet, an acid solution outlet, an alkali solution inlet and an alkali solution outlet; the mixing reactor 4 is provided with an ammonia solution inlet;

[0066] The iron phosphate wastewater pipeline, the regulating tank 1, the lifting pump 11 and the safety filter 2 are connected in sequence;

[0067] The security filter 2 is connected to the acid liquid inlet of the deammoniation membrane device 3;

[0068] The acid liquid outlet of the deammonification membrane device 3 is connected to the mixing reactor 4;

[0069] The mixing reactor 4, the inclined plate sedimentation tank 5, the ultrafiltration booster pump 61, the multi-media filter 62 and the ultrafiltration device 63 are connected in sequence;

[0070] The ultrafiltration device 63 is connected to the alkali solution inlet of the deamination membrane device 3;

[0071] The alkali liquid outlet of the deammonification membrane device 3 is connected to the reverse osmosis device 7;

[0072] The reverse osmosis device 7 and the MVR evaporator 8 are connected.

[0073] Example 2

[0074] The method for treating ferric phosphate wastewater provided in this embodiment adopts the ferric phosphate wastewater treatment system of Example 1, and specifically comprises the following steps:

[0075] S1, the iron phosphate wastewater in the iron phosphate wastewater pipeline flows into the regulating tank 1, and the iron phosphate wastewater in the regulating tank 1 enters the security filter 2 through the lifting pump 11 for filtration to obtain filtered wastewater; wherein, the pH of the iron phosphate wastewater is 2.4, the suspended solids content is 572 mg / L, and the conductivity is 13560 us / cm; the pH of the filtered wastewater is 2.4, the suspended solids content is 237 mg / L, and the conductivity is 13530 us / cm.

[0076] S2. The wastewater filtered in step S1 enters the deamination membrane device 3 from the acid solution inlet, flows through the outer filaments of the deamination membrane, and adsorbs ammonia nitrogen on the wastewater entering from the alkali solution inlet before flowing out from the acid solution outlet. The pH of the wastewater flowing out of the acid solution outlet is 3.3, the suspended solid content is 301 mg / L, and the conductivity is 13540 us / cm; in the deamination membrane device 3, the flow rate of the wastewater is 1 t / h.

[0077] S3. The wastewater flowing out of the acid outlet enters the mixing reactor 4, and ammonia water with a concentration of 22wt% is added to the mixing reactor 4. The pH of the system is adjusted to 8.6h and stirred for 15min to coagulate and precipitate the metal impurities in the system. Then, the wastewater enters the inclined plate sedimentation tank 5 and precipitates for 1h for mud and water diversion. The pH of the wastewater obtained after mud and water diversion is 8.6, the suspended solid content is 872mg / L, and the conductivity is 14120us / cm.

[0078] S4. After the mud and water are separated, the wastewater passes through the ultrafiltration booster pump 61 and enters the multi-media filter 62 and the ultrafiltration device 63 for filtration to obtain filtered wastewater. The pH of the filtered wastewater is 8.5, the suspended solid content is 1 mg / L, and the conductivity is 14150 us / cm.

[0079] S5. Use a plate and frame heat exchanger to control the temperature of the wastewater after filtering in step S4 at 35°C, and then enter the deammonification membrane device 3 from the alkali solution inlet. After the ammonia nitrogen in the wastewater is absorbed, it flows out from the alkali solution outlet. The pH of the wastewater flowing out of the alkali solution outlet is 7.1, the suspended solid content is 2 mg / L, and the conductivity is 13700 us / cm.

[0080] S6. The wastewater flowing out of the alkali solution outlet enters the reverse osmosis (RO) device 7 for reverse osmosis to obtain production pure water and concentrated liquid; the concentrated liquid enters the MVR evaporator 8 for evaporation and crystallization to obtain ammonium sulfate.

[0081] Although the present invention has been illustrated and described using specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features therein may be replaced by equivalents, without departing from the spirit and scope of the present invention. However, these modifications or replacements do not deviate from the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A system for treating iron phosphate wastewater, characterized in that: It includes a first filtering unit, a deamination membrane device, a mixing reactor, a sedimentation tank and a second filtering unit connected in sequence; the deamination membrane device is provided with a deamination membrane; The second filtering unit is connected to the ammonia removal membrane device; The deamination membrane device is provided with an acid solution inlet, an acid solution outlet, an alkali solution inlet and an alkali solution outlet; The first filter unit is connected to the acid solution inlet of the deammoniation membrane device; The acid liquid outlet of the deammonification membrane device is connected to the mixing reactor; The second filter unit is connected to the alkali solution inlet of the deamination membrane device; The ferric phosphate wastewater treatment system further comprises a reverse osmosis device and an MVR evaporator connected in sequence; The reverse osmosis device is connected to the alkaline solution outlet of the deammoniation membrane device.

2. The ferric phosphate wastewater treatment system according to claim 1, characterized in that: It also includes a regulating tank; the outlet of the regulating tank is connected to the first filtering unit.

3. The ferric phosphate wastewater treatment system according to claim 2, characterized in that: The regulating tank is connected to the first filtering unit via a lifting pump.

4. The ferric phosphate wastewater treatment system according to claim 1, characterized in that: The first filter unit includes a security filter.

5. The ferric phosphate wastewater treatment system according to claim 1, characterized in that: The mixing reactor is provided with an ammonia water inlet.

6. The ferric phosphate wastewater treatment system according to claim 1, characterized in that: The sedimentation tank comprises an inclined plate sedimentation tank.

7. The ferric phosphate wastewater treatment system according to claim 1, characterized in that: The second filtration unit includes an ultrafiltration booster pump, a multi-media filter and an ultrafiltration device which are connected in sequence; the ultrafiltration booster pump is connected to the sedimentation tank, and the ultrafiltration device is connected to the alkali solution inlet of the deammoniation membrane device.

8. The ferric phosphate wastewater treatment system according to claim 2, characterized in that: It also includes an iron phosphate wastewater pipeline; the outlet of the iron phosphate wastewater pipeline is connected to the regulating tank.

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