Recycling method of iron phosphate wastewater

Abstract

The invention belongs to the technical field of wastewater treatment in the new energy industry, and particularly relates to an iron phosphate wastewater recycling method which comprises the following steps: wastewater pretreatment, membrane treatment and evaporative crystallization treatment. The wastewater pretreatment comprises mother liquor pretreatment and washing water pretreatment; the membrane treatment comprises high-pressure acid-resistant reverse osmosis membrane treatment, high-pressure nanofiltration membrane treatment, medium-pressure reverse osmosis membrane treatment and low-pressure reverse osmosis membrane treatment; according to the invention, when the operation pressure is less than or equal to 6.5 MPa, the TDS of the strong brine can reach 190000 mg / L; the operation energy consumption of the membrane system is reduced, the operation stability of the membrane system is improved, the MVR water treatment amount is reduced by more than 20%, and the investment cost of the MVR section is greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment in the new energy industry, and particularly relates to a method for recycling phosphoric acid iron wastewater. Background Art

[0002] Ferric phosphate is an ideal precursor material for the positive electrode materials of automotive lithium-ion power batteries, grid energy storage batteries, and power tool batteries. Phosphoric acid iron wastewater is highly concentrated acidic inorganic wastewater containing ammonia nitrogen (NH 3 - N), sulfate (SO 4 2- ), and total phosphorus (TP) generated during the production of the positive electrode material ferric phosphate. Currently, the main methods for treating wastewater from ferric phosphate production are as follows: (1) The lime method has the disadvantage that it can only remove total phosphorus, and directly discharges without considering the total salt exceeding the standard, generating a large amount of sludge that is difficult to treat and causing greater pollution to the surrounding water environment. (2) Stripping of high-concentration ammonia nitrogen and precipitation of magnesium ammonium phosphate have a long process flow, require a large amount of alkali to adjust the pH, and need to be adjusted back after the reaction, resulting in high treatment costs. (3) The biological method refers to using microorganisms to digest and decompose wastewater containing nitrogen, sulfur, and phosphorus impurities, and has disadvantages such as high requirements for water quality, strict treatment conditions, and large floor area.

[0003] The above technologies for treating wastewater from ferric phosphate production generally have problems such as complex processes, high costs, and inability to fully recycle and utilize. Currently, the treatment of ferric phosphate production wastewater also includes a method combining conventional pretreatment and membrane concentration, that is, the mother liquor and washing water are all adjusted to a medium to slightly alkaline pH with ammonia water to remove heavy metal ions in the water, and then acid is added for back adjustment. The pretreated water is concentrated and separated by multi-stage reverse osmosis membranes of low pressure, medium pressure, high pressure, and ultra-high pressure. It has the following problems: (1) The conventional method of adjusting the pH value of phosphoric acid iron wastewater followed by precipitation + filtration has a long process flow, high investment cost, and cannot recover the ferric phosphate sludge leaked from the device into the water; (2) The operating pressure of the conventional ultra-high pressure membrane concentration system is ≥8 MPa, with high operating energy consumption and poor operating stability; (3) The TDS of the concentrated brine of the conventional membrane concentration system can only reach 150000 mg / L, with a large amount of water in the evaporation crystallization section and high investment cost.

[0004] In addition, the patent with publication number CN114716089A discloses a new process for treating iron phosphate wastewater by multi-stage membrane concentration, which includes a pretreatment stage, a nanofiltration membrane concentration stage and a multi-effect evaporation stage. The pretreatment stage includes a laminated filtration stage and an ultrafiltration stage; the nanofiltration membrane concentration stage includes a multi-stage reverse osmosis (RO) stage, a mother liquor reverse osmosis stage, a multi-stage wash water reverse osmosis stage and a clean water reverse osmosis stage. Although the step of adding alkali solution to adjust the pH value of the mother liquor is effectively avoided, the following problems exist: (1) The mother liquor contains a relatively high concentration of heavy metal ions such as Fe and Mn. If ammonia is not added to adjust the pH value to remove them, the risk of fouling and blockage of the mother liquor membrane concentration system will increase, resulting in unstable operation; (2) The pH value of the membrane concentrated concentrated water is 1 to 3, which does not meet the conditions for directly entering the MVR (pH 4 to 6). It is necessary to add ammonia water to adjust the pH value before entering the MVR for evaporation and crystallization. The introduction of part of the water here will increase the investment cost of the MVR. At the same time, since the heavy metal ions are not removed, the purity of the crystalline product ammonium sulfate will be reduced.

[0005] In order to reduce the investment and operation cost of the evaporation and crystallization stage, it is necessary to increase the concentration of the solution as much as possible in the membrane treatment stage to reduce the amount of water treated in the evaporation and crystallization stage. However, due to the structural limitations of the spiral reverse osmosis membrane assembly, when the operating pressure of the membrane assembly is ≥70bar, the risks of membrane assembly bursting, deformation, and compaction will be greatly increased. According to Table 1, the water quality of a 200,000 tons / year iron phosphate production wastewater mother liquor, when the TDS is 150,000 mg / L, its osmotic pressure is 80.25 bar. Therefore, conventional ultra-high pressure reverse osmosis membrane concentration needs to be operated at a pressure of >80bar, and the concentrated water TDS can reach 150,000 mg / L.

[0006] Table 1 Water quality of mother liquor from ferric phosphate production wastewater

[0007]

[0008] Therefore, it is urgent to solve the problems of leakage and reuse of existing iron phosphate wastewater, unstable operation of ultra-high pressure membrane system and low concentration. Summary of the invention

[0009] In view of the deficiencies of the prior art, the present invention proposes a method for recycling ferric phosphate wastewater.

[0010] This is achieved specifically through the following technical solutions:

[0011] A method for recycling iron phosphate wastewater comprises the following steps: wastewater pretreatment, membrane treatment, and evaporation crystallization treatment; the wastewater pretreatment comprises mother liquor pretreatment and wash water pretreatment; the membrane treatment comprises high-pressure acid-resistant reverse osmosis membrane treatment, high-pressure nanofiltration membrane treatment, medium-pressure reverse osmosis membrane treatment, and low-pressure reverse osmosis membrane treatment.

[0012] The wash water pretreatment is to send the wash water from the wash water regulating tank into the DFL filter for filtration after aeration, and the effluent enters the subsequent treatment process, and the backwash water is sent to the iron phosphate production device; the turbidity of the DFL effluent is <1NTU, and SDI≤3.

[0013] The mother liquor pretreatment is to send the mother liquor collected in the mother liquor regulating water tank into the reaction tank, add ammonia water to adjust the pH to 6-8.5, and after aeration and flocculant addition, send it to the integrated water purifier for filtration treatment, the effluent enters the subsequent treatment process, the backwash water is returned to the mother liquor regulating water tank, and the sludge is sent to the sludge concentration system.

[0014] The high-pressure acid-resistant reverse osmosis membrane treatment is to send the effluent obtained from the wash water pretreatment into a heat exchanger for cooling and then enter the high-pressure acid-resistant reverse osmosis membrane treatment system for pre-desalting and concentration treatment, the reverse osmosis produced water enters the intermediate water tank and is sent to the subsequent treatment process, and the concentrated water enters the mother liquor regulating water tank.

[0015] The high-pressure nanofiltration membrane treatment is to send the effluent obtained from the mother liquor pretreatment into a heat exchanger, cool it, add 30% sulfuric acid to adjust the pH to 5-6, and then enter the external pressure ultrafiltration device to control the effluent turbidity ≤0.5NTU and SDI ≤3 before entering the high-pressure nanofiltration membrane treatment system for pre-desalting and concentration treatment. The nanofiltration membrane produced water enters the water production tank, and the concentrated water enters the MVR feed tank and is sent to the MVR for evaporation and crystallization.

[0016] The medium-pressure reverse osmosis membrane treatment is to feed the produced water obtained by high-pressure nanofiltration membrane treatment into the medium-pressure reverse osmosis membrane treatment system for pre-desalination and concentration treatment, the reverse osmosis produced water enters the intermediate water tank, and the concentrated water is sent to the high-pressure reverse osmosis membrane treatment.

[0017] The low-pressure reverse osmosis membrane treatment is to send the MVR distilled water into the intermediate water tank, mix it with the medium-pressure reverse osmosis product water and the high-pressure acid-resistant reverse osmosis product water, and then enter the low-pressure reverse osmosis membrane treatment system for desalination treatment. The reverse osmosis product water enters the pure water reuse water tank, and the concentrated water goes to the medium-pressure reverse osmosis membrane for treatment.

[0018] Preferably, in order to reduce the unsafety of adding the reagents and reduce the temperature rise caused by the heat released during the adding process, the concentration of the ammonia water is 20% and the concentration of the sulfuric acid is 30%.

[0019] Preferably, the filter element of the DFL filter is composed of a support layer and a surface filter layer, the liquid filtration grade is 1 μm, the effluent turbidity is less than 1 NTU, and the effluent meets the inlet water quality conditions of the reverse osmosis membrane system, extending the service life of the membrane element.

[0020] Preferably, the mother liquor is pretreated by adding ammonia water to adjust the pH to 8, which can remove Fe, Mn and Mg in the water to the maximum extent, reduce the risk of fouling in the rear-end mother liquor membrane concentration system, ensure the stable operation of the membrane system, and reduce impurities in the MVR feed liquid, thereby improving the quality of ammonium sulfate.

[0021] Preferably, before the water produced by the integrated water purifier enters the ultrafiltration device, 30% sulfuric acid is added to adjust the pH to 5.5, which can reduce the risk of fouling of the ultrafiltration membrane and ensure that the pH value of the mother liquor membrane treatment concentrate is around 5. It can directly enter the MVR for evaporation and crystallization treatment without adding drugs to adjust the pH value.

[0022] Preferably, all backwash water, flushing discharge water, and chemical cleaning liquid from the reverse osmosis membrane treatment, ultrafiltration membrane treatment, and nanofiltration membrane treatment are collected into a miscellaneous water tank and then pumped into a mother liquor regulating water tank to achieve zero discharge.

[0023] Preferably, the design process of the high pressure nanofiltration membrane treatment system is shown in Figure 2 As shown: the design is a four-stage concentration, the concentrated water from the second stage enters the third stage, the produced water from the first and second stages goes to the medium-pressure reverse osmosis membrane treatment system, the produced water from the third and fourth stages flows back to the water inlet of the high-pressure nanofiltration membrane, and the concentrated water from the third and fourth stages enters the MVR stage. Compared with the conventional two-stage membrane system, it has the following advantages: the first and second stages use high-rejection nanofiltration membranes, the third and fourth stages use low-rejection nanofiltration membranes, and there is no need to set up high-pressure pumps or intermediate water tanks between the first and second stages and the third and fourth stages, saving investment costs, operating energy consumption and floor space.

[0024] Preferably, the design water inlet pressure of the DFL filter is less than 3 bar, the design operating pressure of the external pressure ultrafiltration membrane system is 0.05-0.15 bar, the design operating pressure of the high-pressure nanofiltration membrane treatment system is 55-65 bar, the design operating pressure of the high-pressure acid-resistant reverse osmosis membrane treatment system is 50-60 bar, the design operating pressure of the medium-pressure reverse osmosis membrane treatment system is 25-35 bar, and the design operating pressure of the low-pressure reverse osmosis membrane treatment system is 8-13 bar.

[0025] Preferably, the DFL filter has a design flux of 1400lmh, the external pressure ultrafiltration membrane system has a design flux of ≤40lmh, the high pressure nanofiltration membrane treatment system has a design flux of 9-11lmh, the medium pressure reverse osmosis membrane treatment system has a design flux of 18-20lmh, the high pressure acid-resistant reverse osmosis membrane treatment system has a design flux of 13-16lmh, and the low pressure reverse osmosis membrane treatment system has a design flux of 25-30lmh.

[0026] Preferably, the iron phosphate mother liquor and the wash water are aerated for 20 to 30 minutes before entering the pretreatment system. Firstly, the ferrous ions in the wastewater can be oxidized into ferric ions, and secondly, the excess hydrogen peroxide in the wastewater can be decomposed faster.

[0027] Preferably, the DFL filter has a design recovery rate of 95%, the ultrafiltration membrane system has a design recovery rate of 90%, the high-pressure nanofiltration membrane treatment system has a design recovery rate of 52.5%, the high-pressure acid-resistant reverse osmosis membrane treatment system has a design recovery rate of 64%, the medium-pressure reverse osmosis membrane treatment system has a design recovery rate of 80%, and the low-pressure reverse osmosis membrane treatment system has a design recovery rate of 84%.

[0028] Beneficial effects:

[0029] (1) The pH value of the wash water is not adjusted, and the high turbidity wash water is directly treated with the DFL filter, which reduces the pretreatment process and reduces the pretreatment cost. The DFL filter intercepts the iron phosphate sludge leaked from the iron phosphate production device for reuse, reducing the loss caused by leakage from the front-end plate frame.

[0030] (2) The wash water membrane treatment uses a high-pressure acid-resistant reverse osmosis membrane. Compared with the conventional reverse osmosis membrane operating at pH 3 to 10, the high-pressure acid-resistant reverse osmosis membrane can operate stably under acidic conditions and the pH can be as low as 1 during long-term operation.

[0031] (3) The mother liquor pretreatment adopts an integrated water purifier instead of the conventional high-density sedimentation tank, which cleverly combines the processes of coagulation reaction, suspension clarification, inclined tube sedimentation, filtration, sludge concentration, quartz sand / manganese sand filtration, etc., and is equipped with a simple and efficient special tube test mixer, realizing an excellent turbidity removal equipment with a high degree of automation of hydraulic self-control or program control, and the turbidity of the produced water can reach ≤3NTU; at the same time, compared with the conventional high-density sedimentation tank, it occupies a small area and has a short construction period.

[0032] (4) After the mother liquor is added with 20% ammonia water to adjust the pH value to 8, most of the heavy metal ion impurities in the wastewater can be removed, and then 30% sulfuric acid is added to adjust the pH value to 5-6. This provides water quality conditions for the subsequent MVR evaporation stage to form type I fertilizer-grade ammonium sulfate. At the same time, adding acid to adjust the pH value can reduce the risk of fouling of the membrane system.

[0033] (5) Conventional mother liquor membrane concentration uses a high-pressure reverse osmosis membrane system, whose operating pressure is greater than 8MPa, and the TDS of the brine reaches 150,000 mg / L. The mother liquor membrane treatment system of the present invention adopts a high-pressure nanofiltration membrane one-stage four-stage design, with high-rejection nanofiltration membranes used in the first and second stages, and low-rejection nanofiltration membranes used in the third and fourth stages. By utilizing the selective permeability of the nanofiltration membrane, its overall interception rate for iron phosphate wastewater is relatively low, overcoming the influence of the osmotic pressure of conventional ultra-high pressure membrane concentration, and achieving a higher concentration under lower operating pressure conditions. According to actual on-site operating data, when the operating pressure is ≤6.5MPa, the TDS of the brine can reach 190,000 mg / L; reducing the energy consumption of the membrane system operation, increasing the stability of the membrane system operation, and reducing the MVR treatment water volume by more than 20%, greatly reducing the investment cost of the MVR stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the process flow chart for iron phosphate wastewater treatment;

[0035] Figure 2 High pressure nanofiltration membrane treatment system flow chart;

[0036] Figure 3Operation data graph for wash water DFL filter;

[0037] Figure 4 This is the water balance diagram for iron phosphate wastewater treatment;

[0038] Figure 5 This is the process flow chart of the integrated water purifier. DETAILED DESCRIPTION

[0039] The specific embodiments of the present invention are further described in detail below, but the present invention is not limited to these embodiments, and any improvement or substitution based on the basic spirit of the present embodiment still falls within the scope of protection required by the claims of the present invention.

[0040] Example 1

[0041] The wastewater from a 200,000 ton / year iron phosphate production plant was pilot filtered through a DFL filter and tested in the manner of positive wash → filtration → aeration → drainage → chemical cleaning.

[0042] The DFL filter was pilot-tested, and the operating data are shown in Table 2: it was operated under the conditions of inlet pressure ≤ 0.2MPa, temperature 30-50℃, pH value 2-3, inlet and outlet water pressure difference ≤ 0.15MPa, backwash cycle was 6h, and chemical cleaning cycle was 20-30 days.

[0043] Table 2DFL filter operating conditions

[0044] project Inlet water pressure Inlet water temperature Influent pH Pressure difference Backwash cycle Cleaning cycle unit MPa ℃ - MPa h sky Numeric 0.05～0.25 30～50 2～3 ≤0.15 6 20～30

[0045] DFL filter operation data chart is as follows Figure 2 As shown in the figure: (1) The inlet turbidity fluctuates in the range of 70 to 1000 NTU, and can withstand high turbidity inlet water; (2) When the inlet turbidity fluctuates greatly, the turbidity of the water produced by the DFL filter can be stabilized between 0.2 and 1 NTU. Through aeration backwashing, the flux and turbidity can be well restored, meeting the inlet turbidity requirements of the reverse osmosis membrane system.

[0046] Example 2

[0047] For the wastewater of a 200,000 tons / year iron phosphate production, the mother liquor water is added with 20% ammonia water to adjust the pH value to 8, then aerated, flocculant is added, and then enters the integrated water purifier. The turbidity of the water produced by the integrated water purifier is ≤3NTU. The water produced by the integrated water purifier is cooled only by the heat exchanger, and then 30% sulfuric acid solution is added to adjust the pH value to 5-6, and then enters the ultrafiltration membrane system. The turbidity of the water produced by the ultrafiltration membrane system is <0.5NTU. The pH value of the mother liquor water is 2. After adding 20% ​​ammonia water to different pH values, the removal of various metal ions is shown in Table 3.

[0048] Table 3 Metal ion removal after mother liquor pH adjustment

[0049]

[0050] The test data shows that when the pH value of the mother liquor is adjusted with ammonia water, as the pH value increases, the removal rate of metal ions shows an upward trend. When the pH value of the mother liquor is adjusted to 8, in the water produced by the integrated water purifier, Fe = 0.3 mg / L, Mn = 0.4 mg / L, Ca = 12.7 mg / L, Mg = 4.6 mg / L, and the removal rates of various heavy metal ions are Fe = 97.5%, Mn = 99.4%, Ca = 63.3%, Mg = 98.8%. When the pH is adjusted to 9, the ammonia water dosage is 1.87 times that when the pH is adjusted to 8. Considering the economic situation of ammonia water addition and the removal of metal ions comprehensively, when the pH is adjusted to 8 and enters the integrated water purifier, it can not only meet the requirements for the removal of metal ions, but also reduce the ammonia water addition and lower the operating cost.

[0051] Example 3

[0052] For the phosphoric acid iron production wastewater with a scale of 200,000 tons / year, the mother liquor and washing water enter the membrane treatment system after being treated qualified by the pretreatment device respectively, and are concentrated and separated specifically according to Figure 1 as shown, and the produced water is recycled to the front-end phosphoric acid iron main process device, while the concentrated water enters the MVR evaporation crystallization.

[0053] The water quality of the mother liquor and washing water of a certain 200,000 - ton / year phosphoric acid iron is shown in Table 4.

[0054] Table 4 Incoming water quality table of phosphoric acid iron production wastewater

[0055] name unit Mother liquor Washing water Water volume <![CDATA[m 3 / h]]> 200 400 PH - 2 2.3 COD mg / L 500 20 NH4 mg / L 23942 8030 SO4 mg / L 69796 23003 PO4 mg / L 1624 3819 Mn mg / L 49 41 Fe mg / L 93 11 Mg mg / L 240 268 Ca mg / L 116 10 TDS mg / L 96634 35370

[0056] The operation data of different membrane process treatment systems are shown in Table 5.

[0057] Table 5 Comparison of operation data of membrane treatment devices

[0058]

[0059] As can be seen from the above table, when using the special high - pressure nanofiltration concentration process, under the condition of the highest operating pressure of 6.3 MPa, the TDS of the concentrated brine can reach 204,290 mg / L; while when using the ultra - high - pressure RO membrane concentration process, when the operating pressure is 8.6 MPa, the TDS of the concentrated brine is 150,467 mg / L.

[0060] The water quality of the produced water of a certain 200,000 - ton / year phosphoric acid iron membrane treatment system is shown in Table 6.

[0061] Table 6 Recycled water quality

[0062] name unit Numeric Conductivity μs / cm ≤10 pH - 6～8 SO4 mg / L ≤2 PO4 mg / L ≤0.5 NH4 mg / L ≤1

[0063] The water quality of the concentrated water of a certain 200,000 - ton / year phosphoric acid iron membrane treatment system is shown in Table 7.

[0064] Table 7 Brine Quality

[0065] name unit Numeric TDS mg / L 200132 pH - 5 SO4 mg / L 136073 PO4 mg / L 10856 NH4 mg / L 53177 Mn mg / L 0.6 Fe mg / L 0.3 Mg mg / L 9.4 Ca mg / L 15.7

[0066] The operating data of a 200,000 tons / year iron phosphate membrane treatment unit shows that the mother liquor inlet TDS is 96634 mg / L, the wash water inlet TDS is 35370 mg / L, and a special high-pressure nanofiltration membrane concentration process is used. Under the condition of the maximum operating pressure of the membrane treatment system of 6.3 MPa, the brine TDS can reach 200,000 mg / L, and the conductivity of the recycled water after multi-stage membrane filtration is <10μs / cm.

Claims

1. A method for recycling iron phosphate wastewater, It is characterized in that The method comprises the following steps: wastewater pretreatment, membrane treatment, and evaporation and crystallization treatment; the wastewater pretreatment comprises mother liquor pretreatment and wash water pretreatment; the membrane treatment comprises high-pressure acid-resistant reverse osmosis membrane treatment, high-pressure nanofiltration membrane treatment, medium-pressure reverse osmosis membrane treatment, and low-pressure reverse osmosis membrane treatment.

2. A method for recycling iron phosphate wastewater as claimed in claim 1, It is characterized in that The wash water in the wash water pretreatment wash water regulating water tank is sent to the DFL filter after aeration and filtered, and the effluent enters the subsequent treatment process, and the backwash water is sent to the iron phosphate production device.

3. A method for recycling iron phosphate wastewater as claimed in claim 1, It is characterized in that The mother liquor pretreatment is to send the mother liquor collected in the mother liquor regulating water tank into the reaction tank, add ammonia water to adjust the pH to 6-8.5, and after aeration and flocculant addition, send it to the integrated water purifier for filtration treatment, the effluent enters the subsequent treatment process, the backwash water is returned to the mother liquor regulating water tank, and the sludge is sent to the sludge concentration system.

4. A method for recycling iron phosphate wastewater as claimed in claim 1, It is characterized in that The high-pressure acid-resistant reverse osmosis membrane treatment is to send the effluent obtained from the wash water pretreatment into a heat exchanger for cooling, and then enter the high-pressure acid-resistant reverse osmosis membrane treatment system for pre-desalting and concentration treatment, the reverse osmosis produced water enters the intermediate water tank and is sent to the subsequent treatment process, and the concentrated water enters the mother liquor regulating water tank.

5. A method for recycling iron phosphate wastewater as claimed in claim 1, It is characterized in that The high-pressure nanofiltration membrane treatment is to send the effluent obtained from the mother liquor pretreatment into a heat exchanger for cooling, add 30% sulfuric acid to adjust the pH to 5-6, and then enter the external pressure ultrafiltration device to control the effluent turbidity to ≤0.5NTU and SDI to ≤3. The water produced by the external pressure ultrafiltration device enters the high-pressure nanofiltration membrane treatment system for pre-desalting and concentration treatment, the water produced by the nanofiltration membrane enters the water production tank, the concentrated water enters the MVR feed tank, and is sent to the MVR for evaporation and crystallization.

6. A method for recycling iron phosphate wastewater as claimed in claim 1, It is characterized in that The medium-pressure reverse osmosis membrane treatment is to feed the produced water obtained by high-pressure nanofiltration membrane treatment into the medium-pressure reverse osmosis membrane treatment system for pre-desalination and concentration treatment, the reverse osmosis produced water enters the intermediate water tank, and the concentrated water is sent to the high-pressure acid-resistant reverse osmosis membrane treatment.

7. A method for recycling iron phosphate wastewater as claimed in claim 1, It is characterized in that The low-pressure reverse osmosis membrane treatment is to send the MVR distilled water into the intermediate water tank, mix it with the medium-pressure reverse osmosis product water and the high-pressure acid-resistant reverse osmosis product water, and then enter the low-pressure reverse osmosis membrane treatment system for desalination treatment, the reverse osmosis product water enters the pure water reuse water tank, and the concentrated water goes to the medium-pressure reverse osmosis membrane for treatment.

8. A method for recycling iron phosphate wastewater as claimed in claim 3, It is characterized in that The concentration of the ammonia water is 20%.

9. A method for recycling iron phosphate wastewater as claimed in claim 5, It is characterized in that The concentration of sulfuric acid is 30%.

Images