Treatment method of foil washing wastewater

Abstract

The invention relates to the technical field of wastewater treatment, and particularly discloses a treatment method of foil washing wastewater. The treatment method of the foil washing wastewater provided by the invention comprises the following steps: tempering and destabilizing, flocculating, precipitating, filtering and desalting, wherein the tempering and destabilizing step comprises the following steps: firstly, adjusting the pH value of the foil washing wastewater to 7-8; the flocculation step is as follows: adding a bactericide, polyaluminum ferric chloride and polyacrylamide into the foil washing wastewater subjected to tempering and destabilization; the pH value of the foil washing wastewater raw water is 3-4, the phosphorus content is 30-60 mg / L, the boron content is 1-2 mg / L, and the suspended matter concentration is 300-1000 mg / L. According to the treatment method of the foil washing wastewater, the phosphorus content, the boron content and the suspended matter concentration of the foil washing wastewater can be reduced; moreover, regenerated demineralized water with different conductivities can be obtained, so that different water demands can be met, the recycling of wastewater resources is achieved, and good economic benefits are achieved.

Description

Technical Field

[0001] The present application relates to the technical field of wastewater treatment, and in particular to a method for treating foil washing wastewater. Background Art

[0002] A large amount of foil washing wastewater is generated in the electrode foil forming process. The characteristics of these foil washing wastewater are: low salt content and organic impurities, but serious excess of phosphorus concentration, boron concentration and suspended solids, which seriously affects the ecological environment. Existing foil washing wastewater treatment methods include biological treatment, ion exchange and precipitation. The biological treatment method occupies a large area, requires large investment, and has many application restrictions; the ion exchange equipment is relatively expensive and inconvenient to maintain, and it is extremely difficult to treat when the phosphorus concentration and boron concentration in the wastewater are high; the precipitation method has simple facilities and is easy to operate, but the treatment effect is average.

[0003] In addition, most current electronic production plants are also facing problems such as water shortage, high industrial water prices and sewage fees. Therefore, it is necessary to provide a method for treating foil washing wastewater with simple operation, small footprint and excellent treatment effect to achieve the treatment and recycling of foil washing wastewater. Summary of the invention

[0004] In order to reduce the phosphorus content, boron content and suspended matter content in foil washing wastewater, the present application provides a method for treating foil washing wastewater.

[0005] The method for treating foil washing wastewater provided in this application adopts the following technical scheme:

[0006] A method for treating foil washing wastewater, comprising the following steps: conditioning and destabilization, flocculation, precipitation, filtration, and desalination;

[0007] Conditioning and destabilization: First, adjust the pH of the foil-washing wastewater to 7-8 to destabilize the foil-washing wastewater. Phosphoric acid and boric acid in the water react and precipitate to form white floccules.

[0008] Flocculation: Add fungicide, polyaluminium ferric chloride and polyacrylamide to the foil-washing wastewater after conditioning and destabilization, and mix them quickly and evenly under the action of a stirrer. The fungicide inhibits and kills the microorganisms in the foil-washing wastewater, and a small amount of organic matter is initially oxidized and decomposed; the addition of polyaluminium ferric chloride and polyacrylamide can react with the white flocs to form larger solid flocs;

[0009] Sedimentation: Adopt inclined plate sedimentation, send the flocculated water to the inclined plate sedimentation area, adopt inclined tube sedimentation to separate mud and water, and use the shallow pool sedimentation principle. The inclined tube is used to change the direction of water flow and thus change the relationship between the floc sinking speed and the water flow speed, reduce the sedimentation distance of suspended particles in the water, improve the removal rate of suspended matter, and also increase the hydraulic load, with a smaller pool and a higher water flow rate;

[0010] Filtration: including coarse filtration and fine filtration;

[0011] The coarse filtration uses a multi-media filter filled with quartz sand and anthracite in a weight ratio of 2:1, which is used to remove sediment, suspended matter, and colloidal impurities in the water, perform preliminary purification on the produced water, reduce the turbidity of the incoming water, and meet the water inlet requirements for subsequent fine filtration;

[0012] The fine filtration includes microfiltration, ultrafiltration, primary security filtration, primary reverse osmosis, secondary security filtration and secondary reverse osmosis. The microfiltration adopts a self-cleaning filter, which can produce water from the multi-media filter and intercept large suspended particles in the water; the ultrafiltration can remove suspended matter, colloids, microorganisms and macromolecular organic substances in the water, so that the effluent water quality meets the inlet requirements of the primary reverse osmosis, and the recovery rate and membrane flux of the ultrafiltration are controlled within the above range; the security filtration adopts a security filter, which can effectively intercept the fine mechanical impurities and broken activated carbon particles leaked in the pretreatment equipment, and the reverse osmosis can remove dissolved salts, organic molecules, silica colloids, macromolecular substances and particles not removed by pretreatment in the water;

[0013] Before the primary security filtration, it is necessary to add a scale inhibitor, a reducing agent and a non-oxidizing bactericide to the primary reverse osmosis influent. The scale inhibitor is used to inhibit scaling on the nanofiltration and reverse osmosis concentrate side, the reducing agent is used to reduce the residual chlorine in the pre-treatment process, and the non-oxidizing bactericide is used to prevent the growth of microorganisms and bacteria and contaminate the reverse osmosis membrane. Before the secondary security filtration, it is also necessary to add a pH regulator to the secondary reverse osmosis influent.

[0014] Desalination: EDI desalination is used for desalination. The water produced by the secondary reverse osmosis enters the EDI, and is refined by continuous electric desalination to obtain regenerated desalted water.

[0015] The present application provides a method for treating foil-washing wastewater. In the primary treatment of the treatment method, by adjusting the pH, then adding a bactericide, polyaluminium ferric chloride and polyacrylamide, phosphorus-containing substances, boron-containing substances and microorganisms in the foil-washing wastewater are precipitated and form solid floccules, thereby creating good conditions for subsequent solid-liquid separation. The present application destabilizes the foil-washing wastewater by adjusting the pH, and substances such as phosphoric acid and boric acid in the water react and precipitate to form white floccules; the bactericide inhibits and kills the microorganisms in the foil-washing wastewater, and a small amount of organic matter is initially oxidized and decomposed; the addition of polyaluminium ferric chloride and polyacrylamide can react with the white floccules to form larger solid floccules.

[0016] In the present application, the pH value of the foil washing wastewater raw water is 3-4, the phosphorus content is 30-60 mg / L, the boron content is 1-2 mg / L, and the suspended matter concentration is 300-1000 mg / L; suspended matter refers to solid matter suspended in water, including suspended particles, colloidal substances and soluble organic matter.

[0017] Preferably, based on the effective ingredients of the agent, the added amount of the bactericide is 0.05-0.15‰ of the weight of the foil washing wastewater, the added amount of polyaluminium ferric chloride is 0.03-0.21‰ of the weight of the foil washing wastewater, and the added amount of polyacrylamide is 0.0005-0.002‰ of the weight of the foil washing wastewater.

[0018] More preferably, the addition amount of the polyaluminium ferric chloride can be 0.08-0.1‰, 0.08-0.15‰, 0.08-0.21‰, 0.1-0.15‰, 0.1-0.21‰ or 0.15-0.21‰ of the weight of the foil washing wastewater.

[0019] More preferably, the added amount of the polyaluminium ferric chloride can also be 0.08‰, 0.1‰, 0.15‰ or 0.21‰ of the weight of the foil washing wastewater.

[0020] More preferably, the added amount of the polyacrylamide can be 0.0005-0.001‰, 0.0005-0.0015‰, 0.0005-0.0002‰, 0.001-0.0015‰, 0.001-0.002‰ or 0.0015-0.002‰ of the weight of the foil washing wastewater.

[0021] More preferably, the added amount of the polyacrylamide can also be 0.0005‰, 0.001‰, 0.0015‰ or 0.002‰ of the weight of the foil washing wastewater.

[0022] In the present application, the fungicide component is isothiazolinone, and the CAS number is 26172-55-4.

[0023] In the flocculation step of the present application, rapid stirring can be used to evenly mix and quickly coagulate foil washing wastewater, polyaluminium ferric chloride and polyacrylamide, thereby producing alum flocs with larger volume and density, thereby ensuring the quality of the generated flocs and creating conditions for subsequent precipitation.

[0024] Preferably, the hydraulic retention time SRT of the inclined plate sedimentation is 60-90 min.

[0025] The design of this application uses inclined tube sedimentation for mud and water separation. Due to the high efficiency of sedimentation, the concentration of suspended matter separated from the sludge layer in the sedimentation tank is very low. The inclined tube also increases the sedimentation area. Using the principle of shallow pool sedimentation, the inclined tube helps to change the direction of water flow and thus change the relationship between the floc sinking speed and the water flow speed, reducing the distance for suspended particles in the water to settle, improving the removal rate of suspended matter, and also increasing the hydraulic load, with a smaller tank body and a higher water flow rate. Compared with the ordinary flat plate sedimentation in the related art, the inclined plate sedimentation of this application has a greatly shortened hydraulic retention time SRT, occupies a smaller area, and has a better mud and water separation effect.

[0026] In this application, the impurities such as silt, suspended matter, colloids, etc. in the water can be removed through coarse filtration, the produced water can be preliminarily purified, the turbidity of the incoming water can be reduced, and the incoming water requirements for subsequent fine filtration can be met.

[0027] Preferably, the microfiltration uses a self-cleaning filter; the security filtration uses a security filter, and a PP melt-blown filter element with a pore size of 1-5 μm is installed in the security filter.

[0028] In the present application, the self-cleaning filter can produce water from the multi-media filter, intercept large suspended particles in the water, protect the safe operation of the subsequent ultrafiltration device, and prevent the ultrafiltration membrane element from being blocked by large particles or scratched and damaged, thereby increasing the service life of the ultrafiltration membrane. Ultrafiltration can remove suspended matter, colloids, microorganisms and macromolecular organic substances in the water, so that the effluent water quality meets the water inlet requirements of the first-level reverse osmosis, and by controlling the recovery rate and membrane flux of the ultrafiltration within the above range, it can avoid the membrane assembly from being subjected to a high operating load, so that the membrane assembly has good anti-pollution ability and backwashing and cleaning recovery ability. Security filtration can effectively intercept fine mechanical impurities and broken activated carbon particles leaked in the pretreatment equipment, ensure that these particles do not enter the reverse osmosis water treatment system, and prevent possible residual impurities from clogging the reverse osmosis membrane. Reverse osmosis can remove dissolved salts, organic molecules, silica colloids, macromolecular substances, and particles that have not been removed by pretreatment in water.

[0029] Preferably, in the ultrafiltration step, the recovery rate is set to 80-95%, the membrane flux is set to 30-70LMH, and the effluent water quality reaches turbidity ≤0.2NTU and SDI ≤3.

[0030] In the present application, the role of the reducing agent is to reduce the residual chlorine present in the pre-treatment process. Because the reverse osmosis and nanofiltration composite membranes are very sensitive to residual chlorine, the total cumulative bearing capacity is only 1000mg / lh; therefore, an excessive amount of reducing agent must be added to prevent the oxidation of the membrane desalination layer by the oxidant, resulting in a decrease in the desalination rate of the reverse osmosis and nanofiltration membranes. The role of the scale inhibitor is to add a high-efficiency RO-specific scale inhibitor before the pre-treated raw water enters the nanofiltration and reverse osmosis systems to inhibit scaling on the nanofiltration and reverse osmosis concentrate side. The role of the non-oxidizing bactericide is to prevent the growth of microorganisms and bacteria to contaminate the reverse osmosis membrane without oxidizing the membrane. It is best to regularly add non-oxidizing bactericides to the reverse osmosis inlet water to ensure that the system is not troubled by microbial growth.

[0031] In summary, this application has the following beneficial effects:

[0032] 1. The present application provides a method for treating foil washing wastewater, which can effectively remove phosphorus-containing substances, boric acid, partially soluble organic matter, difficult-to-degrade organic matter, suspended matter, microorganisms, dissolved salts and colloids in the foil washing wastewater, so that the phosphorus content in the foil washing wastewater is reduced to below 5 mg / L, the boron content is reduced to below 0.1 mg / L, and the suspended matter concentration is reduced to below 20 mg / L, which fully meets the sewage discharge standards.

[0033] 2. In the treatment method of foil washing wastewater provided in the present application, desalted water with a conductivity below 400 us / cm can be obtained after the first-level reverse osmosis, and regenerated desalted water with a conductivity below 0.5 us / cm can be obtained after EDI desalination. The above-mentioned desalted waters with different conductivities can respectively meet the water quality requirements of recycled water in different process sections, thereby realizing the treatment, recycling and reuse of foil washing wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a flow chart of the method for treating foil washing wastewater provided in this application. DETAILED DESCRIPTION

[0035] The present application provides a method for treating foil washing wastewater, comprising the following steps:

[0036] (1) Adjust to destabilization: First, add NaOH to the foil washing wastewater to adjust the pH of the foil washing wastewater to 7-8.

[0037] (2) Flocculation: Add bactericide (Kason, purchased from Shandong Jinmei Chemical Co., Ltd.), polyaluminium ferric chloride and polyacrylamide to the foil-washing wastewater. Calculated by the effective ingredients of the agents, the amount of bactericide added is 0.05-0.15‰ of the weight of the foil-washing wastewater, the amount of polyaluminium ferric chloride added is 0.03-0.21‰ of the weight of the foil-washing wastewater, and the amount of polyacrylamide added is 0.0005-0.002‰ of the weight of the foil-washing wastewater.

[0038] In the present application, the pH of the raw water of foil washing wastewater is 3-4, the phosphorus content is 30-60 mg / L, the boron content is 1-2 mg / L, and the suspended matter concentration is 300-1000 mg / L.

[0039] (3) Inclined plate sedimentation: The flocculated water is sent to the inclined plate sedimentation area and stays there for 60-90 minutes.

[0040] (4) Coarse filtration: The produced water after the inclined plate sedimentation treatment is pumped into a multi-media filter for preliminary coarse filtration; wherein the multi-media filter is filled with quartz sand and anthracite in a mass ratio of 2:1.

[0041] (5) Fine filtration: The water produced by the multi-media filter enters the self-cleaning filter for microfiltration, and then is sent to the ultrafiltration device for ultrafiltration. The recovery rate is set to 90%, the membrane flux is 40LMH, and the effluent water quality reaches turbidity ≤ 0.2NTU, SDI ≤ 3; then the ultrafiltration water is sent to the first-level security filter, the first-level reverse osmosis device, the second-level security filter and the second-level reverse osmosis device in turn. Among them, the antiscalant, reductant and non-oxidizing bactericide are added before the ultrafiltration water enters the security filter, and a PP melt-blown filter element with a pore size of 5μm is installed in the security filter; the pH regulator is added before the first-level reverse osmosis water enters the second-level security filter.

[0042] (6) EDI desalination: The water produced by the secondary reverse osmosis enters the EDI and is refined by continuous electro-desalination to obtain recycled water.

[0043] The foil washing wastewater used in the present embodiment has a pH of 3.4, a phosphorus content of 54 mg / L, a boron content of 1.7 mg / L, and a suspended solids concentration of 825 mg / L. The drugs, reagents, solvents, etc. used in the present application can all be obtained commercially.

[0044] The present application is further described in detail below in combination with embodiments, performance testing and accompanying drawings.

[0045] Example 1

[0046] Embodiment 1 provides a method for treating foil washing wastewater, comprising the following steps:

[0047] The present application provides a method for treating foil washing wastewater, comprising the following steps:

[0048] (1) Adjust to destabilization: First, add NaOH to the foil washing wastewater to adjust the pH of the foil washing wastewater to 7.2.

[0049] (2) Flocculation: Add bactericide (Kason, purchased from Shandong Jinmei Chemical Co., Ltd.), polyaluminium ferric chloride and polyacrylamide (purchased from Henan Aierfuk Chemical Co., Ltd.) to the foil-washing wastewater. Calculated on the basis of the effective ingredients of the agents, the amount of bactericide added is 0.15‰ of the weight of the foil-washing wastewater, the amount of polyaluminium ferric chloride added is 0.08‰ of the weight of the foil-washing wastewater, and the amount of polyacrylamide added is 0.001‰ of the weight of the foil-washing wastewater.

[0050] (3) Inclined plate sedimentation: The flocculated water is sent to the inclined plate sedimentation area and stays there for 60 minutes.

[0051] (4) Coarse filtration: The produced water after the inclined plate sedimentation treatment is pumped into a multi-media filter for preliminary coarse filtration; wherein the multi-media filter is filled with quartz sand and anthracite in a mass ratio of 2:1.

[0052] (5) Fine filtration: The water produced by the multi-media filter enters the self-cleaning filter for microfiltration, and then is sent to the ultrafiltration device for ultrafiltration. The recovery rate is set to 90%, the membrane flux is 40LMH, and the effluent water quality reaches turbidity ≤ 0.2NTU, SDI ≤ 3; then the ultrafiltration water is sent to the first-level security filter, the first-level reverse osmosis device, the second-level security filter and the second-level reverse osmosis device in turn. Among them, the antiscalant (model DL-FST581), NaHSO3 and non-oxidizing bactericide (purchased from Wanhua Tianhe, item number 202101564) are added before the ultrafiltration water enters the security filter. A PP melt-blown filter element with a pore size of 5μm is installed in the security filter; the pH regulator is added before the first-level reverse osmosis water enters the second-level security filter.

[0053] (6) EDI desalination: The water produced by the secondary reverse osmosis enters the EDI and is refined by continuous electrosalting to obtain regenerated desalted water.

[0054] Embodiment 2-7

[0055] Examples 2-7 respectively provide a method for treating foil washing wastewater.

[0056] The difference between the above embodiment and embodiment 1 is that in step (1), the addition amounts of polyaluminium ferric chloride and polyacrylamide are as shown in Table 1 below.

[0057] Table 1 Addition amount of polyaluminium ferric chloride and polyacrylamide in Examples 2-7

[0058]

[0059] Comparative Example 1

[0060] Comparative Example 1 provides a method for treating foil washing wastewater.

[0061] The difference between the above comparative example and Example 2 is that in step (1), the pH of the foil washing wastewater is adjusted to 6.5.

[0062] Comparative Example 2

[0063] Comparative Example 2 provides a method for treating foil washing wastewater.

[0064] The difference between the above comparative example and Example 2 is that in step (1), the pH of the foil washing wastewater is adjusted to 9.8.

[0065] Comparative Example 3

[0066] Comparative Example 3 provides a method for treating foil washing wastewater.

[0067] The difference between the above comparative example and Example 2 is that the amount of polyaluminium ferric chloride added in step (1) is 0.

[0068] Comparative Example 4

[0069] Comparative Example 4 provides a method for treating foil washing wastewater.

[0070] The difference between the comparative example and Example 2 is that the amount of polyacrylamide added in step (1) is 0.

[0071] Performance testing

[0072] Various indicators of the reclaimed water obtained in the above Examples 1-7 and Comparative Examples 1-4 were tested, and the results are shown in Table 2 below.

[0073] The pH value was tested by pH meter; the phosphorus content was tested by MDS-830 online total phosphorus detector; the boron content was tested by azomethine-H acid photometry; the detection method of suspended solids (SS) in water quality was as follows: the water sample was passed through a filter membrane with a pore size of 0.45μm, and the solid matter retained on the filter membrane and dried at 103-105℃ to constant weight.

[0074] Table 2 Test results of various indicators of foil washing water obtained after treatment in Examples 1-7 and Comparative Examples 1-4

[0075]

[0076] According to the test results in Table 2, the treatment methods for foil-washing wastewater provided in Examples 1-7 of the present application can reduce the phosphorus content in foil-washing wastewater from 54 mg / L to less than 5 mg / L, the boron content from 1.7 mg / L to less than 0.1 mg / L, the suspended matter concentration from 825 mg / L to less than 20 mg / L, and the conductivity to less than 0.5 us / cm. After treatment with the foil-washing wastewater treatment methods of Comparative Examples 1-4, the obtained foil-washing water has a phosphorus content of up to 6.7-10.1 mg / L, a boron content of up to 0.12-0.24 mg / L, and a suspended matter content of up to 21.2-43.3 mg / L. Therefore, it is explained that in the treatment method of foil washing wastewater provided in the present application, the pH of the foil washing wastewater is adjusted to 7-8 in the primary treatment step, and then polyaluminium ferric chloride and polyacrylamide are added to the foil washing wastewater, which can effectively remove phosphorus-containing substances, boron-containing substances and suspended matter in the foil washing wastewater, so that the treated foil washing wastewater fully meets the sewage discharge standards.

[0077] In addition, the foil washing wastewater treated by the foil washing wastewater treatment method provided in this application can be recycled. Taking a Xinjiang Electronic Materials Co., Ltd. as an example, the cost accounting of foil washing wastewater resource recycling is carried out: the cleaning water (foil washing wastewater) of the foil production line of a Xinjiang Electronic Materials Co., Ltd. has a water volume of 200m 3 / h(4000m 3 / d), the wastewater recovery rate is 90%. Without considering the operating cost of the recovery equipment, but only calculating based on the saving of raw water, it can save 24,000 yuan / day in water charges, 720,000 yuan per month on average, and more than 860,000 yuan per year on average. If the reduced sewage discharge fee is added, the economic benefits are very considerable.

[0078] In summary, the treatment method of foil washing wastewater provided in the present application can reduce the phosphorus content, boron content, suspended matter content and other impurities content in the foil washing wastewater. The obtained treated water can be used in various production workshops to achieve wastewater recycling and reuse, solve the problems of regional water resource shortage and high industrial water prices and sewage discharge fees, and has good economic benefits and promotion value.

[0079] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A method for treating foil washing wastewater, characterized in that: The following steps are involved: Conditioning, destabilization, flocculation, precipitation, filtration, and desalination; Conditioning and destabilization: First, adjust the pH of the foil-washing wastewater to 7-8 to destabilize the foil-washing wastewater. Phosphoric acid and boric acid in the water react and precipitate to form white floccules. Flocculation: Add fungicide, polyaluminium ferric chloride and polyacrylamide to the foil-washing wastewater after conditioning and destabilization, and mix them quickly and evenly under the action of a stirrer. The fungicide inhibits and kills the microorganisms in the foil-washing wastewater, and a small amount of organic matter is initially oxidized and decomposed; the addition of polyaluminium ferric chloride and polyacrylamide can react with the white flocs to form larger solid flocs; Sedimentation: Adopt inclined plate sedimentation, send the flocculated water to the inclined plate sedimentation area, adopt inclined tube sedimentation to separate mud and water, and use the shallow pool sedimentation principle. The inclined tube is used to change the direction of water flow and thus change the relationship between the floc sinking speed and the water flow speed, reduce the sedimentation distance of suspended particles in the water, improve the removal rate of suspended matter, and also increase the hydraulic load, with a smaller pool and a higher water flow rate; Filtration: including coarse filtration and fine filtration; The coarse filtration uses a multi-media filter filled with quartz sand and anthracite in a weight ratio of 2:1, which is used to remove sediment, suspended matter, and colloidal impurities in the water, perform preliminary purification on the produced water, reduce the turbidity of the incoming water, and meet the water inlet requirements for subsequent fine filtration; The fine filtration includes microfiltration, ultrafiltration, primary security filtration, primary reverse osmosis, secondary security filtration and secondary reverse osmosis. The microfiltration adopts a self-cleaning filter, which can produce water from the multi-media filter and intercept large suspended particles in the water; the ultrafiltration can remove suspended matter, colloids, microorganisms and macromolecular organic substances in the water, so that the effluent water quality meets the inlet requirements of the primary reverse osmosis, and the recovery rate and membrane flux of the ultrafiltration are controlled within the above range; the security filtration adopts a security filter, which can effectively intercept the fine mechanical impurities and broken activated carbon particles leaked in the pretreatment equipment, and the reverse osmosis can remove dissolved salts, organic molecules, silica colloids, macromolecular substances and particles not removed by pretreatment in the water; Before the primary security filtration, it is necessary to add a scale inhibitor, a reducing agent and a non-oxidizing bactericide to the primary reverse osmosis influent. The scale inhibitor is used to inhibit scaling on the nanofiltration and reverse osmosis concentrate side, the reducing agent is used to reduce the residual chlorine in the pre-treatment process, and the non-oxidizing bactericide is used to prevent the growth of microorganisms and bacteria and contaminate the reverse osmosis membrane. Before the secondary security filtration, it is also necessary to add a pH regulator to the secondary reverse osmosis influent. Desalination: EDI desalination is used for desalination. The water produced by the secondary reverse osmosis enters the EDI, and is refined by continuous electric desalination to obtain regenerated desalted water.

2. The method for treating foil washing wastewater according to claim 1, characterized in that: The raw water of the foil washing wastewater has a pH value of 3-4, a phosphorus content of 30-60 mg / L, a boron content of 1-2 mg / L, and a suspended matter concentration of 300-1000 mg / L.

3. The method for treating foil washing wastewater according to claim 1, characterized in that: Calculated on the basis of the effective ingredients of the agent, the amount of fungicide added is 0.05-0.15‰ of the weight of the foil washing wastewater, the amount of polyaluminium ferric chloride added is 0.03-0.21‰ of the weight of the foil washing wastewater, and the amount of polyacrylamide added is 0.0005-0.002‰ of the weight of the foil washing wastewater.

4. The method for treating foil washing wastewater according to claim 3, characterized in that: The addition amount of the polyaluminium ferric chloride is 0.08-0.1‰, 0.08-0.15‰, 0.08-0.21‰, 0.1-0.15‰, 0.1-0.21‰ or 0.15-0.21‰ of the weight of the foil washing wastewater.

5. The method for treating foil washing wastewater according to claim 4, characterized in that: The addition amount of the polyaluminium ferric chloride is 0.08‰, 0.1‰, 0.15‰ or 0.21‰ of the weight of the foil washing wastewater.

6. The method for treating foil washing wastewater according to claim 3, characterized in that: The added amount of the polyacrylamide is 0.0005-0.001‰, 0.0005-0.0015‰, 0.0005-0.0002‰, 0.001-0.0015‰, 0.001-0.002‰ or 0.0015-0.002‰ of the weight of the foil washing wastewater.

7. The method for treating foil washing wastewater according to claim 6, characterized in that: The added amount of the polyacrylamide is 0.0005‰, 0.001‰, 0.0015‰ or 0.002‰ of the weight of the foil washing wastewater.

8. The method for treating foil washing wastewater according to claim 1, characterized in that: The total hydraulic retention time SRT of the inclined plate sedimentation is 60-90 min.

9. The method for treating foil washing wastewater according to claim 1, characterized in that: A PP melt-blown filter element with a pore size of 1-5 μm is installed in the security filter.

10. The method for treating foil washing wastewater according to claim 1, characterized in that: In the ultrafiltration step, the recovery rate is set to 80-95%, the membrane flux is set to 30-70LMH, and the effluent water quality reaches turbidity ≤0.2NTU and SDI ≤3.

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