Method for recovering phosphorus in phosphorus-containing dirt

Abstract

The invention relates to the field of environmental protection and resource recycling, and discloses a method for recycling phosphorus in phosphorus-containing dirt, which comprises the following steps: in the presence of acidifying bacteria, sequentially carrying out anaerobic fermentation treatment and solid-liquid separation treatment on the phosphorus-containing dirt to obtain phosphorus-containing supernate and solid-phase dirt; an iron ion source is introduced into the phosphorus-containing supernatant for mixing reaction, and a blue iron ore crystal and a phosphorus-removed supernatant are obtained; by calculating the iron ion utilization rate and the phosphate ion recovery rate in the primary mixing reaction, the addition amount of a subsequent iron ion source is guided, so that the iron ion utilization rate and the phosphate ion recovery rate can both meet the expected level. The method provided by the invention not only can realize efficient recovery of the phosphorus element, but also remarkably improves the utilization rate of iron ions, and realizes effective recovery and utilization of resources.

Description

Technical Field

[0001] The invention relates to the field of environmental protection and resource recycling, and in particular to a method for recovering phosphorus from phosphorus-containing waste. Background Art

[0002] Phosphorus is one of the important elements necessary for maintaining the activities of living organisms and modern agricultural production. For living organisms, phosphorus is a component of nucleoproteins, adenosine phosphates and many enzymes, and plays a key role in the energy transfer, storage and information inheritance of organisms. For modern agriculture, phosphate fertilizer, as a basic fertilizer, breaks the limitations of the natural cycle of agricultural materials and greatly improves the productivity of land. As a non-metallic element with active chemical properties, phosphorus exists mostly in the form of phosphates in nature, which are divided into inorganic phosphorus (IP) and organic phosphorus (OP). Among them, OP mainly exists in the form of phosphate esters, such as phospholipids, nucleic acids, phosphoinositides and phosphate esters. IP mainly exists in the form of minerals, which is also the main phosphorus storage reservoir in nature. It includes sedimentary rock mines and igneous rock mines, accounting for more than 80% of the world's total phosphate reserves.

[0003] However, in sewage sludge, most phosphorus exists in three forms: (1) physiological phosphorus, such as organic phosphorus such as DNA and RNA; (2) polyphosphate stored in microbial cells; and (3) phosphorus fixed by physical and chemical means, which cannot react with Fe 2+ Direct reaction, so it must be converted into soluble phosphates and released from the solid phase into the liquid phase before it can be recycled.

[0004] For example, CN112279478A discloses a method for recovering phosphorus in excess sludge in the form of blue iron ore, specifically: (1) placing the sludge in a container and allowing it to settle naturally for 24 hours at room temperature, removing the supernatant, and obtaining a sludge concentrated sample; (2) adding ferric chloride to the sludge concentrated sample obtained in step (1), introducing nitrogen to react in a sealed reactor, maintaining an anaerobic environment, using mechanical stirring to mix the reaction system materials uniformly, controlling the fermentation pH, temperature and time, and performing anaerobic fermentation; (3) adjusting the pH of the fermented supernatant to 7, allowing it to settle naturally for 1 hour to recover the precipitate, and then heating and drying the precipitate to obtain blue iron ore crystals. The method provided in the prior art recovers iron and phosphorus in the supernatant in the form of blue iron ore by anaerobic fermentation, thereby achieving sludge reduction and resource utilization. However, the prior art has low phosphate ion recovery and iron ion utilization, and other alkaline precipitates, such as calcium hydroxide, iron hydroxide, etc., may exist under the condition of a pH value of 7, so that more blue iron ore impurities are precipitated. Summary of the invention

[0005] The purpose of the present invention is to provide a method for recovering phosphorus from phosphorus-containing waste with both high iron ion utilization rate and high phosphate ion recovery rate.

[0006] In order to achieve the above object, the present invention provides a method for recovering phosphorus from phosphorus-containing waste, the method comprising:

[0007] (1) in the presence of acidifying bacteria, subjecting phosphorus-containing waste to anaerobic fermentation treatment and solid-liquid separation treatment in sequence to obtain a phosphorus-containing supernatant and solid-phase waste; controlling the conditions so that the anaerobic fermentation treatment is carried out under initial conditions of a pH value of 3-6.5;

[0008] (2) performing a mixed reaction I on the phosphorus-containing supernatant and an iron ion source to obtain a mixture I; controlling the amount of the iron ion source added so that the molar ratio of iron ions to phosphate ions in the initial reaction system for the mixed reaction I is 1.5:1;

[0009] (3) defining the phosphate ion concentration in the phosphorus-containing supernatant in step (2) as X, and the iron ion concentration as Y; defining the phosphate ion concentration in the mixture I in step (2) as X1, and the iron ion concentration as Y1; initial iron ion utilization rate α1 = (X-X1) / (1.5X-Y1-Y)×100%, initial phosphate ion recovery rate β1 = (X-X1) / X×100%;

[0010] Repeat the operation of step (1) to obtain the phosphorus-containing supernatant and the solid phase dirt, and mix the phosphorus-containing supernatant with the iron ion source to react I-1 to obtain a mixture I-1;

[0011] If α1<80%, β1>60%, the concentration of iron ions provided by the iron ion source in the initial reaction system of the mixed reaction I-1 is c=(5X-5X1) / 4+Y1+Y;

[0012] If α1>80%, β1<60%, then the concentration of iron ions provided by the iron ion source in the initial reaction system of the mixed reaction I-1 is c=0.9X+1.5X1;

[0013] If α1<80%, β1<60%, then the concentration of iron ions provided by the iron ion source in the starting reaction system of the mixed reaction I-1 is c=9 / 8X+Y+Y1;

[0014] If α1≥80%, β1≥60%, the operation described in step (3) is not performed, or the concentration of iron ions provided by the iron ion source in the starting reaction system of the mixed reaction I-1 is c=1.5XY;

[0015] The units of X, Y, X1, Y1, and c are all mg / L.

[0016] Preferably, in step (1), an acidic substance is introduced into the fermentation system to control the initial pH value of the anaerobic fermentation treatment, and the acidic substance is hydrochloric acid and / or sulfuric acid.

[0017] Preferably, in step (1), the content of phosphorus in the phosphorus-containing waste is ≥ 2 wt%.

[0018] Preferably, in step (1), the conditions of the anaerobic fermentation treatment include: a temperature of 32-35° C., a time of 8-14 days, and a stirring speed of 5-20 rpm.

[0019] Preferably, the initial water content of the fermentation system of the anaerobic fermentation treatment is 60-90 wt%.

[0020] According to a preferred specific embodiment, in step (1), the solid-liquid separation treatment operation includes: sequentially performing the solid-liquid separation treatment by static sedimentation, gravity concentration and mechanical dehydration to obtain the phosphorus-containing supernatant and the solid sludge.

[0021] Preferably, the conditions of the mixed reaction I and the mixed reaction I-1 each independently satisfy the following conditions: the pH value is 3-6.5.

[0022] Preferably, the mixed reaction I and the mixed reaction I-1 are carried out under the same pH condition.

[0023] Preferably, the iron ion source is ferric sulfate and / or ferric chloride.

[0024] Preferably, the phosphate ion recovery rate of the method is ≥ 60%.

[0025] Preferably, the iron ion utilization rate of the method is ≥80%.

[0026] Compared with the prior art, the technical solution provided by the present invention has at least the following advantages:

[0027] The method provided by the invention effectively improves the recovery rate of phosphorus in phosphorus-containing waste, can effectively protect the ecological environment, and realize resource recycling.

[0028] The method provided by the present invention can not only realize the efficient recovery of phosphorus element, but also significantly improve the utilization rate of iron ions, save costs, and is simple to operate and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a schematic flow chart of a preferred method for recovering phosphorus from phosphorus-containing waste. DETAILED DESCRIPTION

[0030] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0031] As mentioned above, the present invention provides a method for recovering phosphorus from phosphorus-containing waste, the method comprising:

[0032] (1) in the presence of acidifying bacteria, subjecting phosphorus-containing waste to anaerobic fermentation treatment and solid-liquid separation treatment in sequence to obtain a phosphorus-containing supernatant and solid-phase waste; controlling the conditions so that the anaerobic fermentation treatment is carried out under initial conditions of a pH value of 3-6.5;

[0033] (2) performing a mixed reaction I on the phosphorus-containing supernatant and an iron ion source to obtain a mixture I; controlling the amount of the iron ion source added so that the molar ratio of iron ions to phosphate ions in the initial reaction system for the mixed reaction I is 1.5:1;

[0034] (3) defining the phosphate ion concentration in the phosphorus-containing supernatant in step (2) as X, and the iron ion concentration as Y; defining the phosphate ion concentration in the mixture I in step (2) as X1, and the iron ion concentration as Y1; initial iron ion utilization rate α1 = (X-X1) / (1.5X-Y1-Y)×100%, initial phosphate ion recovery rate β1 = (X-X1) / X×100%;

[0035] Repeat the operation of step (1) to obtain the phosphorus-containing supernatant and the solid phase dirt, and mix the phosphorus-containing supernatant with the iron ion source to react I-1 to obtain a mixture I-1;

[0036] If α1<80%, β1>60%, the concentration of iron ions provided by the iron ion source in the initial reaction system of the mixed reaction I-1 is c=(5X-5X1) / 4+Y1+Y;

[0037] If α1>80%, β1<60%, then the concentration of iron ions provided by the iron ion source in the initial reaction system of the mixed reaction I-1 is c=0.9X+1.5X1;

[0038] If α1<80%, β1<60%, then the concentration of iron ions provided by the iron ion source in the starting reaction system of the mixed reaction I-1 is c=9 / 8X+Y+Y1;

[0039] If α1≥80%, β1≥60%, the operation described in step (3) is not performed, or the concentration of iron ions provided by the iron ion source in the starting reaction system of the mixed reaction I-1 is c=1.5XY;

[0040] The units of X, Y, X1, Y1, and c are all mg / L.

[0041] Preferably, the phosphorus-containing waste is sludge and / or sewage, preferably sludge.

[0042] The acidifying bacteria described in the present invention refers to a microorganism that decomposes organic matter and produces acidic substances, and can further convert simple compounds into organic acids (such as acetic acid, propionic acid, butyric acid, etc.) and hydrogen. The present invention has no particular limitation on the specific type of the acidifying bacteria, and those skilled in the art can select the acidifying bacteria according to the acidifying bacteria known in the art.

[0043] The acidifying bacteria of the present invention can be the acidifying bacteria existing in the phosphorus-containing sewage itself, or can be introduced into the fermentation system of the anaerobic fermentation treatment by external addition, as long as the phosphorus-containing sewage can be fermented to release the phosphorus element therein. However, in order to obtain a better phosphorus recovery effect, the present invention preferably uses lactic acid bacteria as acidifying bacteria, and the inoculation amount is 5-10% of the total volume of the phosphorus-containing sludge to be treated.

[0044] Preferably, in step (1), an acidic substance is introduced into the fermentation system to control the initial pH value of the anaerobic fermentation treatment, and the acidic substance is hydrochloric acid and / or sulfuric acid.

[0045] Preferably, in step (1), the content of phosphorus in the phosphorus-containing waste is ≥ 2 wt%.

[0046] Preferably, in step (1), the conditions of the anaerobic fermentation treatment include: a temperature of 32-35° C. and a time of 8-14 days.

[0047] Preferably, in step (1), the anaerobic fermentation treatment is carried out under stirring conditions with a rotation speed of 5-20 rpm. Under this specific preferred condition, the destruction of microbial flocs and bubbles can be reduced.

[0048] Preferably, the initial water content of the fermentation system of the anaerobic fermentation treatment is 60-90 wt%.

[0049] According to a preferred specific embodiment, in step (1), the solid-liquid separation treatment operation includes: sequentially performing the solid-liquid separation treatment by static sedimentation, gravity concentration and mechanical dehydration to obtain the phosphorus-containing supernatant and the solid sludge.

[0050] It should be noted that in step (2) of the present invention, the molar ratio of iron ions to phosphate ions in the starting reaction system of the mixed reaction I is 1.5:1, wherein the iron ions include iron ions that may exist in the phosphorus-containing supernatant, rather than just iron ions provided by the iron ion source.

[0051] The mixture I and mixture I-1 of the present invention contain cyanite crystals, and the present invention recovers phosphorus in the phosphorus-containing waste in the form of cyanite crystals. The reaction equation for generating the cyanite crystals is: Fe 3+ +PO4 3- +5H2O→Fe3(PO4)2·8H2O.

[0052] According to a preferred specific embodiment, the method described in the present invention also includes: separating the blue iron ore crystals in the mixture I and / or the mixture I-1 to obtain a dephosphorized supernatant, introducing the dephosphorized supernatant into a sewage treatment pool, and discharging it after the treatment meets the standards.

[0053] Preferably, the conditions of the mixed reaction I and the mixed reaction I-1 are independently satisfied: the pH value is 3-6.5, preferably 4-6.5. The inventors found in their research that controlling the reaction under the preferred pH value condition can improve the precipitation efficiency of blue iron ore crystallization, further improve the utilization rate of iron ions and the recovery rate of phosphate ions.

[0054] Preferably, the mixed reaction I and the mixed reaction I-1 are carried out under the same pH condition.

[0055] More preferably, the mixed reaction I and the mixed reaction I-1 are both carried out at a pH value of 6.5. The inventors have found in their research that under this preferred condition, the method provided by the present invention can have a higher utilization rate of iron ions and a higher recovery rate of phosphate ions.

[0056] Preferably, the present invention adjusts the pH value of the mixed reaction I and / or the mixed reaction I-1 by adding an acidic substance or an alkaline substance; and maintains the floating range of the pH value within ±0.5 of the target value.

[0057] Preferably, the acidic substance is hydrochloric acid and / or sulfuric acid, and the alkaline substance is sodium hydroxide and / or potassium hydroxide; the acidic substance and / or alkaline substance are preferably added to the reaction system in the form of an aqueous solution thereof.

[0058] Preferably, the iron ion source is ferric sulfate and / or ferric chloride.

[0059] Preferably, the phosphate ion recovery rate of the method is ≥ 60%, preferably ≥ 63%.

[0060] Preferably, the iron ion utilization rate of the method is ≥80%, preferably ≥85%.

[0061] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, the raw materials are all commercially available.

[0062] In the following examples, the concentration of the acidified bacteria seed solution used was 2.4×10 6 CFU / mL of lactic acid bacteria.

[0063] Example 1

[0064] (1) 800 mL of phosphorus-containing sludge (phosphorus content of 2%, water content of 86%) was placed in a reaction container, nitrogen was introduced for 15 minutes, oxygen in the reaction container was discharged, hydrochloric acid solution was added to adjust the pH value to 5, the inoculation amount of acidifying bacteria seed liquid was 5% of the total volume of the phosphorus-containing sludge, and anaerobically fermented for 12 days at 35° C. and 20 rpm, and then the fermented product was statically precipitated to separate a first supernatant and bottom phosphorus concentrated sludge, and the bottom phosphorus concentrated sludge was gravity concentrated and mechanically dehydrated in sequence to obtain a second supernatant and dried sludge, and the first supernatant and the second supernatant were mixed together to form a phosphorus-containing supernatant;

[0065] (2) mixing the phosphorus-containing supernatant with an iron ion source (ferric sulfate solution) to perform a reaction I (the pH value is 5, and the amount of the iron ion source added is controlled so that the molar ratio of iron ions to phosphate ions in the initial reaction system is 1.5:1) to obtain a mixture I, and separating blue iron ore crystals and a dephosphorized supernatant;

[0066] (3) The phosphate ion concentration in the phosphorus-containing supernatant in step (2) is X=302.1 mg / L, the iron ion concentration is Y=65.2 mg / L, and the added iron ion concentration is 1.5XY; the phosphate ion concentration in the mixture I in step (2) is X1=102.4 mg / L, and the iron ion concentration is Y1=126.0 mg / L; the initial iron ion utilization rate α1=(X-X1) / (1.5X-Y1-Y)×100%=76.2%, and the initial phosphate ion recovery rate β1=(X-X1) / X×100%=66.1%;

[0067] Repeat the operation of step (1) to obtain a phosphorus-containing supernatant, mix the phosphorus-containing supernatant with an iron ion source (ferric sulfate solution) to react I-1 (pH value is 5) to obtain a mixture I-1, and separate blue iron ore crystals and a dephosphorized supernatant;

[0068] Since α1≤80%, β1>60%, the amount of the iron ion source added is adjusted so that the concentration of the iron ions provided by the iron ion source in the initial reaction system of the mixed reaction I-1 is c=(5X-5X1) / 4+Y1+Y=440.8 mg / L;

[0069] After the reaction, the phosphate ion concentration in the detected mixture I-1 was X2 = 110.6 mg / L, and the iron ion concentration was Y2 = 139.0 mg / L; the adjusted iron ion utilization rate α2 = (X-X2) / (cY-Y2)×100% = 80.9%, and the adjusted phosphate ion recovery rate β2 = (X-X2) / X×100% = 63.4%, both of which were significantly improved.

[0070] Figure 1 A flow chart of the technical solution of preferred embodiment 1 of the present invention is shown.

[0071] Example 2

[0072] (1) 800 mL of phosphorus-containing sludge (phosphorus content of 2%, water content of 86%) was placed in a reaction container, nitrogen was introduced for 15 minutes, oxygen in the reaction container was discharged, hydrochloric acid solution was added to adjust the pH value to 4, the inoculation amount of acidifying bacteria seed liquid was 5% of the total volume of the phosphorus-containing sludge, and anaerobically fermented at 32° C. and 10 rpm for 10 days, and then the fermented product was allowed to settle to separate a first supernatant and bottom phosphorus concentrated sludge, and the bottom phosphorus concentrated sludge was gravity concentrated and mechanically dehydrated in turn to obtain a second supernatant and dried sludge, and the first supernatant and the second supernatant were mixed together to form a phosphorus-containing supernatant;

[0073] (2) mixing the phosphorus-containing supernatant with an iron ion source (ferric chloride solution) to react I (the pH value is 4.0, and the amount of the iron ion source added is controlled so that the molar ratio of iron ions to phosphate ions in the initial reaction system is 1.5:1) to obtain a mixture I, and separating blue iron ore crystals and a dephosphorized supernatant;

[0074] (3) The phosphate ion concentration in the phosphorus-containing supernatant in step (2) is X=345.2 mg / L, the iron ion concentration is Y=68.5 mg / L, and the added iron ion concentration is 1.5XY; the phosphate ion concentration in the mixture I in step (2) is X1=158.8 mg / L, and the iron ion concentration is Y1=228.6 mg / L; the initial iron ion utilization rate α1=(X-X1) / (1.5X-Y1-Y)×100%=84.5%, and the initial phosphate ion recovery rate β1=(X-X1) / X×100%=54.0%;

[0075] Repeat the operation of step (1) to obtain a phosphorus-containing supernatant, mix the phosphorus-containing supernatant with an iron ion source (ferric chloride solution) to react I-1 (pH value is 4.0) to obtain a mixture I-1, and separate blue iron ore crystals and a dephosphorized supernatant;

[0076] Since α1>80% and β1≤60%, the amount of the iron ion source added is adjusted so that the concentration of the iron ions provided by the iron ion source in the initial reaction system of the mixed reaction I-1 is c=0.9X+1.5X1=548.9mg / L;

[0077] After the reaction, the phosphate ion concentration in the detected mixture I-1 was X2 = 138.1 mg / L, and the iron ion concentration was Y2 = 240.2 mg / L; the adjusted iron ion utilization rate α2 = (X-X2) / (cY-Y2)×100% = 86.2%, and the adjusted phosphate ion recovery rate β2 = (X-X2) / X×100% = 60.0%, both of which were significantly improved.

[0078] Example 3

[0079] (1) 800 mL of phosphorus-containing sludge (phosphorus content of 2%, water content of 86%) was placed in a reaction container, nitrogen was introduced for 15 minutes, oxygen in the reaction container was discharged, hydrochloric acid solution was added to adjust the pH value to 3.0, the inoculation amount of acidifying bacteria seed liquid was 5% of the total volume of the phosphorus-containing sludge, and anaerobically fermented at 35° C. and 5 rpm for 14 days, and then the fermented product was statically precipitated to separate a first supernatant and bottom phosphorus concentrated sludge, and the bottom phosphorus concentrated sludge was gravity concentrated and mechanically dehydrated in turn to obtain a second supernatant and dried sludge, and the first supernatant and the second supernatant were mixed together to form a phosphorus-containing supernatant;

[0080] (2) mixing the phosphorus-containing supernatant with an iron ion source (ferric sulfate solution) to perform a reaction I (the pH value is 3.0, and the amount of the iron ion source added is controlled so that the molar ratio of iron ions to phosphate ions in the initial reaction system is 1.5:1) to obtain a mixture I, and separating blue iron ore crystals and a dephosphorized supernatant;

[0081] (3) The phosphate ion concentration in the phosphorus-containing supernatant in step (2) is X=366.0 mg / L, the iron ion concentration is Y=70.2 mg / L, and the added iron ion concentration is 1.5XY; the phosphate ion concentration in the mixture I in step (2) is X1=183.0 mg / L, and the iron ion concentration is Y1=231.5 mg / L; the initial iron ion utilization rate α1=(X-X1) / (1.5XY-Y1)×100%=74.0%, and the initial phosphate ion recovery rate β1=(X-X1) / X×100%=50%;

[0082] Repeat the operation of step (1) to obtain a phosphorus-containing supernatant, mix the phosphorus-containing supernatant with an iron ion source (ferric sulfate solution) to react I-1 (pH value is 3.0) to obtain a mixture I-1, and separate blue iron ore crystals and a dephosphorized supernatant;

[0083] Since α1≤80% and β1≤60%, the amount of the iron ion source added is adjusted so that the concentration of the iron ions provided by the iron ion source in the initial reaction system of the mixed reaction I-1 is c=9 / 8X+Y+Y1=713.5 mg / L;

[0084] After the reaction, the phosphate ion concentration in the detected mixture I-1 was X2 = 117.2 mg / L, and the iron ion concentration was Y2 = 335.2 mg / L; the adjusted iron ion utilization rate α2 = (X-X2) / (cY-Y2)×100% = 80.8%, and the adjusted phosphate ion recovery rate β2 = (X-X2) / X×100% = 68.0%, both of which were significantly improved.

[0085] It can be seen from the above results that the technical solution provided by the present invention can effectively improve the recovery rate of phosphorus in phosphorus-containing waste to at least 60%, and can also achieve an iron ion utilization rate of more than 80%, thereby ensuring the recovery and rational utilization of resources to the greatest extent.

[0086] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for recovering phosphorus from phosphorus-containing waste, characterized in that: The method includes: (1) in the presence of acidifying bacteria, subjecting phosphorus-containing waste to anaerobic fermentation treatment and solid-liquid separation treatment in sequence to obtain a phosphorus-containing supernatant and solid-phase waste; controlling the conditions so that the anaerobic fermentation treatment is carried out under initial conditions of a pH value of 3-6.5; (2) performing a mixed reaction I on the phosphorus-containing supernatant and an iron ion source to obtain a mixture I; controlling the amount of the iron ion source added so that the molar ratio of iron ions to phosphate ions in the initial reaction system for the mixed reaction I is 1.5:1; (3) defining the phosphate ion concentration in the phosphorus-containing supernatant in step (2) as X, and the iron ion concentration as Y; defining the phosphate ion concentration in the mixture I in step (2) as X1, and the iron ion concentration as Y1; initial iron ion utilization rate α1 = (X-X1) / (1.5X-Y1-Y)×100%, initial phosphate ion recovery rate β1 = (X-X1) / X×100%; Repeat the operation of step (1) to obtain the phosphorus-containing supernatant and the solid phase dirt, and mix the phosphorus-containing supernatant with the iron ion source to react I-1 to obtain a mixture I-1; If α1<80%, β1>60%, the concentration of iron ions provided by the iron ion source in the initial reaction system of the mixed reaction I-1 is c=(5X-5X1) / 4+Y1+Y; If α1>80%, β1<60%, then the concentration of iron ions provided by the iron ion source in the initial reaction system of the mixed reaction I-1 is c=0.9X+1.5X1; If α1<80%, β1<60%, then the concentration of iron ions provided by the iron ion source in the starting reaction system of the mixed reaction I-1 is c=9 / 8X+Y+Y1; If α1≥80%, β1≥60%, the operation described in step (3) is not performed, or the concentration of iron ions provided by the iron ion source in the starting reaction system of the mixed reaction I-1 is c=1.5XY; The units of X, Y, X1, Y1, and c are all mg / L.

2. The method according to claim 1, characterized in that In step (1), an acidic substance is introduced into the fermentation system to control the initial pH value of the anaerobic fermentation treatment, and the acidic substance is hydrochloric acid and / or sulfuric acid.

3. The method according to claim 1 or 2, characterized in that: In step (1), the phosphorus content in the phosphorus-containing waste is ≥ 2 wt%.

4. The method according to claim 1 or 2, characterized in that: In step (1), the conditions of the anaerobic fermentation treatment include: temperature of 32-35°C, time of 8-14 days, stirring speed of 5-20 rpm; And / or, the initial water content of the fermentation system of the anaerobic fermentation treatment is 60-90wt%.

5. The method according to claim 1 or 2, characterized in that: In step (1), the solid-liquid separation treatment comprises: sequentially performing the solid-liquid separation treatment by static sedimentation, gravity concentration and mechanical dehydration to obtain the phosphorus-containing supernatant and the solid sludge.

6. The method according to claim 1 or 2, characterized in that: The conditions of the mixed reaction I and the mixed reaction I-1 are independently satisfied: the pH value is 3-6.

5.

7. The method according to claim 6, characterized in that The mixed reaction I and the mixed reaction I-1 are carried out under the same pH condition.

8. The method according to claim 1 or 2, characterized in that: The iron ion source is ferric sulfate and / or ferric chloride.

9. The method according to claim 1 or 2, characterized in that: The phosphate ion recovery rate of the method is ≥60%.

10. The method according to claim 9, characterized in that The iron ion utilization rate of the method is ≥80%.

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