A method for deep treatment and reuse of acidic phosphorus-containing wastewater

Abstract

The present invention discloses a method for deep treatment and reuse of acidic phosphorus-containing wastewater, comprising: separating the wastewater from sediment to obtain phosphorus-containing wastewater and sludge 1; adding electrolyte salts to the phosphorus-containing wastewater, stirring and performing an inhibition reaction; adding alkali to the treated phosphorus-containing wastewater to adjust the pH to obtain a colloidal wastewater; performing solid-liquid separation on the colloidal wastewater to obtain sludge 2 and separated wastewater; performing coagulation and sedimentation on the separated wastewater to remove low-concentration phosphorus and simultaneously reduce the concentration of suspended matter in the wastewater, thereby obtaining sludge 3 and precipitated wastewater; performing membrane separation on the precipitated wastewater to remove harmful ions, thereby completing deep treatment and reuse of the wastewater. The method of the present invention solves the problem of self-polymerization of acidic phosphorus-containing catalyst wastewater during the pH adjustment process by adding alkali, and can reduce the phosphorus content of ultra-high-concentration phosphorus-containing catalyst wastewater exceeding 10,000 mg / L to below 0.5 mg / L after treatment, thereby achieving efficient phosphorus removal of ultra-high-phosphorus-containing catalyst wastewater.

Description

Technical Field

[0001] The invention relates to a method for treating and reusing wastewater, in particular to a method for deep treatment and reusing acidic phosphorus-containing wastewater, and belongs to the field of wastewater treatment. Background Art

[0002] In recent years, with the rapid development of the catalyst production industry, compounds such as aluminosilicates have been widely used, but the wastewater produced has high turbidity and complex components. In addition, in order to adjust the acid-base activity, electronic and geometric structure of the catalyst and improve the performance of the catalyst, catalyst additives need to be added during catalyst production. Phosphorus-containing additives are one of them. However, with the addition of phosphorus additives, a large amount of high-concentration phosphorus-containing wastewater will be generated. For the main Al-containing 3+ PO4 3- Ionic catalyst wastewater contains phosphorus in the range of 10,000-15,000 mg / L, a pH of 0.5-2.0, and total dissolved solids of 30,000-50,000 mg / L. If left untreated, this wastewater will have a significant impact on subsequent sewage treatment systems. Therefore, the need for simple, rapid, low-cost, and efficient treatment of this type of phosphorus-containing wastewater has become a key concern.

[0003] Because this type of ultra-high-concentration phosphorus-containing wastewater has a large discharge volume and high total phosphorus content, it increases the operating load of sewage treatment plants. Therefore, it is crucial to develop low-cost, effective, and in-situ phosphorus removal technologies that can be retrofitted and upgraded. Furthermore, if wastewater recycling is achieved during phosphorus removal, the reduction in wastewater discharge will not only reduce the pressure on sewage treatment plants, but also save water and reduce energy consumption, ultimately lowering the overall operating costs of sewage treatment plants.

[0004] At present, the main treatment technologies for phosphorus-containing wastewater at home and abroad are chemical, biological and adsorption methods. Among them, the chemical method mainly uses flocculation and precipitation to treat inorganic and high-concentration phosphorus-containing wastewater. This method has good phosphorus removal effect and stable operation; the biological method mainly uses A / O, A 2 Processes such as sintering, sintering, and sintering-branch reactors (SBRs) are used to treat low-concentration and organic phosphorus-containing wastewater. Adsorption methods primarily utilize low-cost, high-adsorption adsorbents such as fly ash and zeolite to treat low-concentration phosphorus-containing wastewater. However, some ultra-high-concentration phosphorus-containing wastewaters currently appearing in industrial production are difficult to treat through flocculation and precipitation methods to ensure that phosphorus discharge in the wastewater meets discharge standards. Combination processes, such as chemical-biological and chemical-adsorption methods, are often used. These processes are suitable for treating phosphorus-containing wastewater with concentrations less than 2000 mg / L. However, there are few reports on the treatment of ultra-high-concentration phosphorus-containing catalyst wastewater with a pH less than 2 and a phosphorus content exceeding 10,000 mg / L. Therefore, the development of an efficient wastewater phosphorus removal method is urgently needed.

[0005] Chinese patent CN112742345A discloses a method for removing phosphorus and nitrogen from wastewater using modified diatomaceous earth. The method involves adding the diatomaceous earth to a sulfuric acid solution or a hydrochloric acid solution for a first modification step. Solid anhydrous magnesium sulfate is then added and stirred to obtain a semi-muddy modified diatomaceous earth mixture. Solid sodium phosphate is then added to the resulting mixture for a second modification step. The modified diatomaceous earth is then added to the aeration tank of the biological treatment section of the wastewater treatment plant or to the effluent of the aeration process section to remove phosphorus and nitrogen from the wastewater. This invention utilizes chemical precipitation combined with biological methods to remove nitrogen and phosphorus from wastewater, but the optimal ratio of the reagents is determined based on the total amount of ammonia nitrogen and the ratio of phosphate ions, and the treatment effect is not significant for wastewater with extremely high phosphorus content.

[0006] Chinese patent CN111995104A discloses a process for removing phosphorus and fluoride from industrial wastewater. The process involves adjusting the pH of the wastewater to 2-3, gradually adding calcium hydroxide and stirring until the pH reaches 10-11, adding a flocculant and centrifuging, filtering to obtain a first filtrate, measuring the calcium ion content of the first filtrate, adding a slight excess of sodium carbonate and stirring, centrifuging and filtering to obtain a second filtrate, adding sulfuric acid to adjust the pH to 6-8, and allowing the solution to stand for 1 hour before filtering. This invention utilizes a chemical precipitation method for removing phosphorus and fluoride from industrial wastewater, but this method is difficult to apply to phosphorus removal from strongly acidic, high-phosphorus catalyst wastewater.

[0007] Chinese patent CN111547939A discloses a phosphorus removal process for high-concentration COD wastewater. The process involves discharging the wastewater into a primary treatment tank, where insoluble particulate matter, suspended solids, and floating matter are physically removed, discharging liquid 1. Liquid 1 undergoes anaerobic treatment to degrade macromolecular matter into small molecules, discharging liquid 2. Liquid 2 then enters an electrochemical water treatment device, where it undergoes electrochemical treatment to discharge a low-phosphorus wastewater. The process then proceeds to a secondary sedimentation tank and a deammonification process. This invention utilizes anaerobic treatment to reduce COD in the wastewater, electrochemical phosphorus removal, and a deammonification membrane to remove ammonia. While effective at removing high-concentration COD, it is less effective at removing phosphorus.

[0008] Chinese patent CN112678990A discloses a method for treating phosphate-containing wastewater and its application. The method involves adding acid to adjust the pH of the wastewater to 3-6, adding magnesium salt and ammonium salt, and stirring to obtain a reaction solution. Alkaline solution is then added to adjust the pH of the reaction to 7-8, precipitating magnesium ammonium phosphate solids. Solid-liquid separation is then used to reduce the total phosphorus in the wastewater. This invention significantly removes total phosphorus from wastewater, but is not suitable for phosphorus removal from strongly acidic, high-phosphorus catalyst wastewater.

[0009] Ultra-high concentration phosphorus-containing wastewater has a large discharge volume and high total phosphorus content, which increases the operating load of the sewage treatment plant. Given the limitations of the above existing technologies, how to remove phosphorus from strongly acidic, high-phosphorus catalyst wastewater is an urgent problem to be solved. Summary of the Invention

[0010] The object of the present invention is to provide a method for deep treatment and reuse of acidic phosphorus-containing wastewater. The method solves the problem of self-aggregation of ultra-high-concentration phosphorus-containing catalyst wastewater with a pH of less than 2 and a phosphorus content of more than 10,000 mg / L, so that the pH can be smoothly adjusted and the total phosphorus content is reduced to below 0.5 mg / L through solid-liquid separation and coagulation precipitation. The wastewater is then reused through a membrane separation unit.

[0011] To achieve the above-mentioned object, the present invention provides a method for deep treatment and reuse of acidic phosphorus-containing wastewater, which comprises the following steps:

[0012] (1) Separating the wastewater into sediment to obtain phosphorus-containing waste liquid and sludge 1;

[0013] (2) adding electrolyte salts to the phosphorus-containing waste liquid obtained in step (1), stirring and homogenizing, and performing an inhibition reaction;

[0014] (3) adding alkali to the phosphorus-containing waste liquid after the inhibition reaction in step (2) to adjust the pH of the phosphorus-containing waste liquid to 3-7 to obtain a sol-like waste liquid

[0015] (4) performing solid-liquid separation on the sol-like waste liquid obtained in step (3) to obtain sludge 2 and separated wastewater;

[0016] (5) subjecting the separated wastewater obtained in step (4) to coagulation and sedimentation to remove low-concentration phosphorus and simultaneously reduce the concentration of suspended matter in the wastewater to obtain sludge 3 and precipitated wastewater;

[0017] (6) The wastewater after sedimentation is subjected to membrane separation to remove harmful ions, thereby achieving deep treatment and reuse of the wastewater.

[0018] In the method for advanced treatment and reuse of acidic phosphorus-containing wastewater of the present invention, in step (1), the method for separating the sediment is not particularly limited. For example, but not limited to, the sediment separation may be performed by centrifugation or filter pressing. The resulting sludge 1, which primarily contains SiO2, can be dehydrated and transported for reuse. The preferred time for centrifugation or filter pressing is 15 to 45 minutes.

[0019] In the method for deep treatment and reuse of acidic phosphorus-containing wastewater of the present invention, in step (2), the electrolyte salt is preferably at least one of NaCl, ZnCl2, MgCl2 and KCl; the present invention does not particularly limit the amount of electrolyte salt added, preferably, the amount of electrolyte salt added is 3g / L to 7g / L.

[0020] In the method for deep treatment and reuse of acidic phosphorus-containing wastewater of the present invention, in step (2), the present invention does not particularly limit the temperature and time of the inhibition reaction. Preferably, the reaction temperature is 20-35° C. and the reaction time is 5-30 min.

[0021] In the method for deep treatment and reuse of acidic phosphorus-containing wastewater of the present invention, in step (3), the pH is adjusted by adding an alkaline compound and adjusting the pH to 3 to 7. The present invention does not particularly limit the type of the alkaline compound, and the alkaline compound can be a base or an alkaline salt. Preferably, the alkaline compound is at least one of an inorganic base and an organic base; for example, sodium hydroxide, potassium hydroxide, N-methyldiethanolamine, etc., but the present invention is not limited thereto.

[0022] In the method for deep treatment and reuse of acidic phosphorus-containing wastewater of the present invention, in step (4), the present invention does not particularly limit the method of solid-liquid separation, for example but not limited to, the solid-liquid separation method is at least one of natural sedimentation, centrifugation, and filter press.

[0023] In the method for deep treatment and reuse of acidic phosphorus-containing wastewater of the present invention, in step (5), coagulation and sedimentation can remove low-concentration phosphorus and reduce the concentration of suspended matter in the wastewater, ultimately reducing the total phosphorus in the wastewater to 0.5 mg / L. The present invention does not particularly limit the method of coagulation and sedimentation, for example, but not limited to, the addition of a precipitant, the precipitant being at least one of CaCl2, Al2(SO4)3, and basic polyaluminum chloride. The present invention does not particularly limit the amount of the precipitant added, preferably, the amount of the precipitant added is 2 g / L to 6 g / L.

[0024] In the method for deep treatment and reuse of acidic phosphorus-containing wastewater of the present invention, in step (6), the present invention does not particularly limit the mode of membrane separation. Preferably, the membrane separation is a microfiltration membrane + a reverse osmosis membrane, or an ultrafiltration membrane + a reverse osmosis membrane.

[0025] The present invention can also be described in detail as follows:

[0026] (1) The catalyst wastewater is centrifuged or filtered to obtain phosphorus-containing waste liquid and sludge 1. The phosphorus-containing waste liquid enters the subsequent wastewater treatment unit. The sludge 1 mainly contains SiO2, which can be dehydrated and transported for use. The centrifugation or filtration time is 15 min to 45 min. (2) 3 g / L to 7 g / L of strong electrolyte salts are added to the phosphorus-containing waste liquid treated in step (1) and stirred until completely dissolved. The strong electrolyte salts are preferably NaCl, ZnCl2, MgCl2, and KCl. (3) Alkali is added to the phosphorus-containing waste liquid treated in step (2) to adjust the pH to 3 to 7, and the waste liquid is in a sol state. (4) The sol-like waste liquid obtained in step (3) is subjected to solid-liquid separation. (5) The separated wastewater obtained in step (4) is subjected to coagulation and sedimentation to remove low-concentration phosphorus and reduce the concentration of suspended matter in the wastewater, ultimately reducing the total phosphorus in the wastewater to 0.5 mg / L. The precipitant is one or more of CaCl2, Al2(SO4)3, and basic polyaluminium chloride, and the dosage is 2 g / L to 6 g / L. (6) The wastewater after coagulation and precipitation in step (5) is subjected to membrane separation to deeply remove harmful ions in the wastewater and realize wastewater reuse. The membrane separation is a microfiltration membrane + reverse osmosis membrane, or an ultrafiltration membrane + reverse osmosis membrane.

[0027] The present invention reduces total phosphorus and suspended solids content through solid-liquid separation, polymerization inhibition, pH adjustment, solid-liquid separation, and coagulation and sedimentation, thereby reducing the subsequent treatment load. Furthermore, the membrane separation system of the present invention effectively removes harmful ions from wastewater, enabling wastewater recycling, reducing wastewater discharge, lowering the amount of fresh water injected, conserving water resources, and lowering the overall operating costs of the sewage treatment plant.

[0028] The present invention solves the problem of self-polymerization of acidic phosphorus-containing catalyst wastewater during the process of adding alkali to adjust pH. By adding strong electrolyte salts, the salt effect is used to prevent colloid contact, reduce the chance of collision and sedimentation, and make Al(OH) 2+ 、Al(OH)2 + and AlO2 - etc. exist in the form of monomers, thereby preventing the rapid self-aggregation of the colloid, so that the pH of the strongly acidic and high-concentration phosphorus-containing wastewater can be smoothly adjusted, and by adjusting the pH value and solid-liquid separation, the phosphorus in the wastewater can be removed in the form of sludge.

[0029] The present invention can reduce the phosphorus content of ultra-high-concentration phosphorus-containing catalyst wastewater exceeding 10,000 mg / L to below 0.5 mg / L after treatment, thereby achieving efficient phosphorus removal from ultra-high-phosphorus-containing catalyst wastewater, while reducing suspended matter and electrical conductivity in the wastewater, thereby achieving wastewater reuse, dehydrating sludge, reducing discharge volume, and reducing waste treatment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1The present invention is a process flow chart of the method for deep treatment and reuse of acidic phosphorus-containing wastewater. DETAILED DESCRIPTION

[0031] The present invention is described in detail below through examples. The examples are only used to further illustrate the present invention and should not be understood as limiting the scope of protection of the present invention. Personnel in this field can make corresponding non-essential improvements and adjustments based on the above content of the present invention.

[0032] Source of raw materials or equipment: Catalyst wastewater comes from a catalyst plant of PetroChina.

[0033] Evaluation and analysis method: The analysis of total phosphorus was carried out in accordance with GB 11893-89 (ammonium molybdate spectrophotometry).

[0034] Example 1

[0035] Catalyst wastewater was collected, with a pH of 0.82 and a total phosphorus content of 12,933 mg / L. The wastewater was subjected to sediment separation for 30 minutes, yielding phosphorus-containing wastewater and sludge 1. The phosphorus-containing wastewater entered the subsequent wastewater treatment unit. The sludge 1, primarily containing SiO2, was dehydrated and transported to landfill. NaCl was added to the phosphorus-containing wastewater at a dosage of 5 g / L, stirred until completely dissolved, and allowed to react at room temperature for 10 minutes. NaOH was then added with stirring to adjust the pH to 5.0, resulting in a white, colloidal wastewater. Solid-liquid separation was performed by filtration, and the wastewater was coagulated and precipitated, with the sludge discharged from the system. CaCl2 was added to the wastewater after solid-liquid separation at a dosage of 5 g / L, and allowed to settle for 30 minutes. The total phosphorus, suspended matter, and total dissolved solids contents in the supernatant were measured. The supernatant then entered a membrane separation device, and the sludge was discharged from the system. The wastewater undergoes membrane separation, first passing through a microfiltration membrane and then a reverse osmosis membrane to reduce its conductivity, allowing it to be reused. The total phosphorus content in the resulting wastewater after coagulation and sedimentation was 0.45 mg / L, and the suspended solids content was 27 mg / L. After membrane separation, the conductivity of the reused water was 12 μs / cm.

[0036] Example 2

[0037] Catalyst wastewater was collected, with a pH of 0.82 and a total phosphorus content of 12,933 mg / L. The wastewater was subjected to sediment separation for 20 minutes, yielding phosphorus-containing wastewater and sludge 1. The phosphorus-containing wastewater entered the subsequent wastewater treatment unit. The sludge 1, primarily containing SiO2, was dehydrated and transported to landfill. KCl was added to the phosphorus-containing wastewater at a dosage of 3 g / L, stirred until completely dissolved, and allowed to react at room temperature for 15 minutes. NaOH was then added with stirring to adjust the pH to 3.0, resulting in a white, colloidal wastewater. Solid-liquid separation was performed by filtration, and the wastewater was coagulated and precipitated, with the sludge discharged from the system. CaCl2 was added to the wastewater after solid-liquid separation at a dosage of 5 g / L, and allowed to settle for 30 minutes. The total phosphorus, suspended solids, and total dissolved solids contents in the supernatant were measured. The supernatant then entered a membrane separation device, and the sludge was discharged from the system. The wastewater undergoes membrane separation, first passing through a microfiltration membrane and then a reverse osmosis membrane to reduce its conductivity, allowing it to be reused. The total phosphorus content in the resulting wastewater after coagulation and sedimentation was 0.48 mg / L, and the suspended solids content was 29 mg / L. After membrane separation, the conductivity of the reused water was 15 μs / cm.

[0038] Example 3

[0039] Catalyst wastewater was collected with a pH of 0.82 and a total phosphorus content of 12,933 mg / L. The wastewater was subjected to sediment separation for 25 minutes, yielding phosphorus-containing wastewater and sludge 1. The phosphorus-containing wastewater entered the subsequent wastewater treatment unit. The sludge 1, primarily containing SiO2, was dehydrated and transported to landfill. MgCl2 was added to the phosphorus-containing wastewater at a dosage of 7 g / L, stirred until completely dissolved, and allowed to react at room temperature for 20 minutes. N-methyldiethanolamine was then added with stirring to adjust the pH to 7.0, resulting in a white colloidal sol. Solid-liquid separation was performed by filtration, and the wastewater was subjected to coagulation and sedimentation, with the sludge discharged from the system. Al2(SO4)3 was added to the wastewater after solid-liquid separation at a dosage of 3 g / L and allowed to settle for 60 minutes. The total phosphorus, suspended solids, and total dissolved solids contents of the supernatant were measured. The supernatant then entered a membrane separation device, and the sludge was discharged from the system. The wastewater undergoes membrane separation, first passing through a microfiltration membrane and then a reverse osmosis membrane to reduce its conductivity, allowing it to be reused. The total phosphorus content in the resulting wastewater after coagulation and sedimentation was 0.33 mg / L, and the suspended solids content was 24 mg / L. After membrane separation, the conductivity of the reused water was 9 μs / cm.

[0040] Example 4

[0041] Catalyst wastewater was collected with a pH of 1.15 and a total phosphorus content of 13,560 mg / L. The wastewater was subjected to sediment separation for 40 minutes, yielding a phosphorus-containing waste liquid and a sludge 1. The phosphorus-containing waste liquid entered a subsequent wastewater treatment unit. The sludge 1, primarily containing SiO2, was dehydrated and transported for use in cement production. MgCl2 was added to the phosphorus-containing waste liquid at a dosage of 6 g / L, stirred until completely dissolved, and allowed to react at room temperature for 25 minutes. N-methyldiethanolamine was then added with stirring to adjust the pH to 7.0, resulting in a white, colloidal wastewater. Solid-liquid separation was performed by filtration, and the wastewater was subjected to coagulation and sedimentation, with the sludge discharged from the system. CaCl2 was added to the wastewater after solid-liquid separation at a dosage of 6 g / L and allowed to settle for 45 minutes. The total phosphorus, suspended solids, and total dissolved solids contents of the supernatant were measured. The supernatant then entered a membrane separation unit, and the sludge was discharged from the system. The wastewater undergoes membrane separation, first passing through a microfiltration membrane and then a reverse osmosis membrane to reduce its conductivity, allowing it to be reused. The total phosphorus content in the resulting wastewater after coagulation and sedimentation was 0.39 mg / L, and the suspended solids content was 29 mg / L. After membrane separation, the conductivity of the reused water was 10 μs / cm.

[0042] Example 5

[0043] Catalyst wastewater was collected with a pH of 1.64 and a total phosphorus content of 11,535 mg / L. The wastewater was subjected to sediment separation for 40 minutes, yielding phosphorus-containing wastewater and sludge 1. The phosphorus-containing wastewater entered a subsequent wastewater treatment unit. The sludge 1, primarily containing SiO2, was dehydrated and transported for use in glass manufacturing. ZnCl2 was added to the phosphorus-containing wastewater at a dosage of 5 g / L, stirred until completely dissolved, and allowed to react at room temperature for 30 minutes. NaOH was then added with stirring to adjust the pH to 3, resulting in a white colloidal sol. Solid-liquid separation was performed by filtration, and the wastewater was subjected to coagulation and sedimentation, with the sludge discharged from the system. Al2(SO4)3 was added to the wastewater after solid-liquid separation at a dosage of 4 g / L and allowed to settle for 50 minutes. The total phosphorus, suspended solids, and total dissolved solids contents of the supernatant were measured. The supernatant then entered a membrane separation unit, and the sludge was discharged from the system. The wastewater undergoes membrane separation, first passing through an ultrafiltration membrane and then a reverse osmosis membrane to reduce its conductivity, allowing it to be reused. The total phosphorus content in the resulting wastewater after coagulation and sedimentation was 0.32 mg / L, and the suspended solids content was 24 mg / L. After membrane separation, the conductivity of the reused water was 9 μs / cm.

[0044] Example 6

[0045] Catalyst wastewater was collected, with a pH of 0.74 and a total phosphorus content of 10,883 mg / L. The wastewater was subjected to sediment separation for 35 minutes, yielding phosphorus-containing wastewater and sludge 1. The phosphorus-containing wastewater entered the subsequent wastewater treatment unit. The sludge 1, primarily containing SiO2, was dehydrated and transported to landfill. NaCH3COOH was added to the phosphorus-containing wastewater at a dosage of 3 g / L, stirred until completely dissolved, and allowed to react at room temperature for 20 minutes. NaOH was then added with stirring to adjust the pH to 6, resulting in a white, colloidal wastewater. Solid-liquid separation was performed by filtration, and the wastewater was coagulated and precipitated, with the sludge discharged from the system. CaCl2 was added to the wastewater after solid-liquid separation at a dosage of 5 g / L, and allowed to settle for 60 minutes. The total phosphorus, suspended solids, and total dissolved solids contents of the supernatant were measured. The supernatant then entered a membrane separation unit, and the sludge was discharged from the system. The wastewater undergoes membrane separation, first passing through an ultrafiltration membrane and then a reverse osmosis membrane to reduce its conductivity, allowing it to be reused. The total phosphorus content in the resulting wastewater after coagulation and sedimentation is 0.25 mg / L, and the suspended solids content is 25 mg / L. After membrane separation, the conductivity of the reused water is 10 μs / cm.

[0046] Comparative Example 1

[0047] Catalyst wastewater was collected, with a pH of 0.82 and a total phosphorus content of 12,933 mg / L. The wastewater was subjected to sediment separation for 30 minutes, yielding a phosphorus-containing waste liquid and a sludge 1. The phosphorus-containing waste liquid entered the subsequent wastewater treatment unit, while the sludge 1, primarily containing SiO2, was dehydrated and transported to landfill. NaCl was added to the phosphorus-containing waste liquid at a dosage of 5 g / L, stirred until completely dissolved, and allowed to react at room temperature for 5 minutes. NaOH was then added with stirring to adjust the pH to 2.5, resulting in a white, colloidal wastewater. Solid-liquid separation was performed by filtration, and the wastewater was subjected to coagulation and sedimentation, with the sludge discharged from the system. CaCl2 was added to the wastewater after solid-liquid separation at a dosage of 5 g / L, and allowed to settle for 30 minutes. The total phosphorus, suspended solids, and total dissolved solids contents in the supernatant of the wastewater after sedimentation were measured. Due to excessive levels of total phosphorus, suspended solids, and total dissolved solids in the supernatant, the wastewater could not enter the membrane separation unit. The total phosphorus content in the wastewater after coagulation and sedimentation is 575 mg / L, and the suspended solids content is 163 mg / L.

[0048] Comparative Example 2

[0049] Catalyst wastewater was collected with a pH of 1.15 and a total phosphorus content of 13,560 mg / L. The wastewater was subjected to sediment separation for 40 minutes, yielding a phosphorus-containing wastewater and sludge 1. The phosphorus-containing wastewater was fed to a subsequent wastewater treatment unit. The sludge 1, primarily containing SiO2, was dehydrated and transported for cement production. MgCl2 was added to the phosphorus-containing wastewater at a dosage of 6 g / L, stirred until completely dissolved, and allowed to react at room temperature for 25 minutes. N-methyldiethanolamine was then added with stirring to adjust the pH to 8, resulting in a white colloidal sol. Solid-liquid separation was performed by filtration, and the wastewater was subjected to coagulation and sedimentation, with the sludge discharged from the system. CaCl2 was added to the wastewater after solid-liquid separation at a dosage of 6 g / L and allowed to settle for 45 minutes. The total phosphorus, suspended solids, and total dissolved solids contents in the supernatant of the wastewater after sedimentation were measured. The supernatant exceeded the specified levels of total phosphorus, suspended solids, and total dissolved solids and could not be fed to the membrane separation unit. The total phosphorus content in the wastewater after coagulation and sedimentation is 366 mg / L, and the suspended solids content is 117 mg / L.

[0050] Comparative Example 3

[0051] Catalyst wastewater was collected with a pH of 1.64 and a total phosphorus content of 11,535 mg / L. The wastewater was subjected to sediment separation for 40 minutes, yielding a phosphorus-containing waste liquid and a sludge 1. The phosphorus-containing waste liquid was fed to a subsequent wastewater treatment unit. The sludge 1, primarily containing SiO2, was dehydrated and transported for use in glass manufacturing. ZnCl2 was added to the phosphorus-containing waste liquid at a dosage of 5 g / L, stirred until completely dissolved, and allowed to react at room temperature for 30 minutes. NaOH was then added with stirring to adjust the pH to 3, resulting in a white colloidal sol. Solid-liquid separation was performed by filtration, and the wastewater was subjected to coagulation and sedimentation, with the sludge discharged from the system. Al2(SO4)3 was added to the wastewater after solid-liquid separation at a dosage of 0.5 g / L and allowed to settle for 50 minutes. The total phosphorus, suspended solids, and total dissolved solids contents of the supernatant were measured. Due to excessive suspended solids, the supernatant could not enter the membrane separation unit. The total phosphorus content in the wastewater after coagulation and sedimentation is 2.76 mg / L, and the suspended solids content is 85 mg / L.

[0052] Comparative Example 4

[0053] Take catalyst wastewater, the pH value is 0.74, and the total phosphorus is 10883 mg / L. The wastewater is subjected to sediment separation for 35 minutes to obtain phosphorus-containing waste liquid and sludge 1. The phosphorus-containing waste liquid enters the subsequent wastewater treatment unit. The sediment 1 mainly contains SiO2, which is dehydrated and transported for glass manufacturing. NaOH is added to the phosphorus-containing waste liquid to adjust the pH value while stirring, but the pH can only be adjusted to 2.1. If NaOH is added again, a large amount of precipitation will appear and stirring is impossible. Solid-liquid separation is performed by filtration, and the phosphorus content in the filtrate is determined. The total phosphorus in the filtrate obtained above is 5114 mg / L, and the suspended matter is 1284 mg / L.

[0054] From the results of the above examples and comparative examples, it can be seen that the present invention can solve the problem of self-polymerization during the process of adding alkali to adjust the pH. By adding strong electrolyte salts, the salt effect is used to prevent colloid contact, reduce the chance of collision sedimentation, and make Al(OH) 2+ 、Al(OH)2 + and AlO2 - The present invention exists in monomeric form, thereby preventing rapid self-aggregation of colloids, allowing the pH of highly acidic, high-concentration phosphorus-containing wastewater to be smoothly adjusted. Furthermore, by adjusting the pH value and performing solid-liquid separation, phosphorus in the wastewater is removed in the form of sludge. The present invention can reduce the phosphorus content of ultra-high-concentration phosphorus-containing catalyst wastewater exceeding 10,000 mg / L to below 0.5 mg / L after treatment, achieving efficient phosphorus removal from ultra-high-concentration phosphorus-containing catalyst wastewater. It also reduces suspended matter and electrical conductivity in the wastewater, enabling wastewater reuse. Furthermore, the sludge is dehydrated, reducing the volume of wastewater discharged and lowering waste treatment costs.

[0055] Of course, the present invention may have many other embodiments and variations thereof. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and variations based on the present invention, but these corresponding changes and variations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for deep treatment and reuse of acidic phosphorus-containing wastewater, characterized in that: The following steps are involved: (1) Separating the acidic phosphorus-containing wastewater into sediment to obtain phosphorus-containing waste liquid and sludge 1; (2) adding electrolyte salts to the phosphorus-containing waste liquid obtained in step (1), stirring and homogenizing, and performing an inhibition reaction; (3) adding alkali to the phosphorus-containing waste liquid after the inhibition reaction in step (2) to adjust the pH of the phosphorus-containing waste liquid to 3-7, thereby obtaining a sol-like waste liquid; (4) performing solid-liquid separation on the sol-like waste liquid obtained in step (3) to obtain sludge 2 and separated wastewater; (5) The separated wastewater obtained in step (4) is subjected to coagulation and sedimentation to remove low-concentration phosphorus and reduce the concentration of suspended matter in the wastewater, thereby obtaining sludge 3 and precipitated wastewater; (6) The wastewater after precipitation is subjected to membrane separation to remove harmful ions, thereby achieving deep treatment and reuse of acidic phosphorus-containing wastewater; The pH of the acidic phosphorus-containing wastewater is less than 2 and the phosphorus content exceeds 10,000 mg / L; Among them, step (2) adds electrolyte salts to prevent colloid contact by using salt effect, reducing the chance of collision sedimentation, and making Al(OH) 2+ 、Al(OH)2 + and AlO2 - Existing in monomeric form, thus preventing the colloid from self-aggregating rapidly; In step (2), the electrolyte salt is at least one of NaCl, ZnCl2, MgCl2 and KCl; the amount of the electrolyte salt added is 3g / L~7g / L; In step (2), the temperature of the inhibition reaction is 20-35° C., and the time of the inhibition reaction is 5-30 min.

2. The method according to claim 1, characterized in that In step (1), the sediment is separated by centrifugation or filter pressing, and the time for separating the sediment is 15 minutes to 45 minutes.

3. The method according to claim 1, characterized in that In step (3), the pH is adjusted by adding an alkaline compound and adjusting the pH to 3-7; the alkaline compound is at least one of an inorganic base and an organic base.

4. The method according to claim 1, wherein In step (4), the solid-liquid separation is at least one of natural sedimentation, centrifugation and filter press.

5. The method according to claim 1, wherein In step (5), a precipitant is added during the coagulation and sedimentation process, and the precipitant is at least one of CaCl2, Al2(SO4)3 and basic polyaluminium chloride; the amount of the precipitant added is 2 g / L to 6 g / L.

6. The method according to claim 1, characterized in that In step (6), the membrane separation is first passing through a microfiltration membrane and then passing through a reverse osmosis membrane, or first passing through an ultrafiltration membrane and then passing through a reverse osmosis membrane.

Images