阅读说明：本技术 一种富集分离污泥厌氧消化上清液中磷的方法 (Method for enriching and separating phosphorus in sludge anaerobic digestion supernatant ) 是由 孙健 尚依依 薛崇灏 赵平歌 张格红 于 2021-07-19 设计创作，主要内容包括：本发明公开了一种富集分离污泥厌氧消化上清液中磷的方法,包括以下步骤：步骤1、过滤污泥厌氧消化上清液中的悬浮物；步骤2、将过滤处理后的污泥厌氧消化上清液通入复合材料固定床,复合材料固定床吸附磷后,排出流出液；当流出液中磷浓度为0.1-1mg/L时,停止向复合材料固定床通入污泥厌氧消化上清液；步骤3、步骤2完成后,再将洗脱液通入复合材料固定床,并从复合材料固定床排出包含洗脱液和磷酸盐溶液的混合溶液；步骤4、向所述包含洗脱液和磷酸盐溶液的混合溶液内添加氯化镁和氯化铵,形成磷酸铵镁沉淀,流出低浓度洗脱液。解决了现有离子交换法中,对磷的吸附容量不够高、需要调节污泥厌氧消化液pH值、存在有机物污染的问题。(The invention discloses a method for enriching and separating phosphorus in sludge anaerobic digestion supernatant, which comprises the following steps: step 1, filtering suspended matters in the supernatant of the anaerobic digestion of the sludge; step 2, introducing the filtered sludge anaerobic digestion supernatant into a composite material fixed bed, and discharging effluent liquid after the composite material fixed bed adsorbs phosphorus; when the phosphorus concentration in the effluent liquid is 0.1-1mg/L, stopping introducing the supernatant liquid of the anaerobic digestion of the sludge into the composite material fixed bed; step 3, after the step 2 is completed, introducing the eluent into the composite material fixed bed, and discharging a mixed solution containing the eluent and the phosphate solution from the composite material fixed bed; and 4, adding magnesium chloride and ammonium chloride into the mixed solution containing the eluent and the phosphate solution to form magnesium ammonium phosphate precipitate, and flowing out the low-concentration eluent. Solves the problems that the adsorption capacity to phosphorus is not high enough, the pH value of the anaerobic digestion solution of the sludge needs to be adjusted and organic pollution exists in the existing ion exchange method.)

1. A method for enriching and separating phosphorus in sludge anaerobic digestion supernatant is characterized by comprising the following steps:

step 1, filtering suspended matters in the supernatant of the anaerobic digestion of the sludge;

step 2, introducing the filtered sludge anaerobic digestion supernatant into a composite material fixed bed, and discharging effluent liquid after the composite material fixed bed adsorbs phosphorus; when the concentration of phosphorus in the effluent liquid is 0.1-1mg/L, stopping introducing the sludge anaerobic digestion supernatant liquid into the composite material fixed bed;

wherein the composite fixed bed is filled with a composite material, and the composite material is an acrylic anion exchange resin loaded with metal particles; the metal particles are any one of hydrated iron oxide, hydrated zirconium oxide and hydrated lanthanum oxide nano particles;

step 3, after the step 2 is completed, introducing eluent into the composite material fixed bed, and discharging a mixed solution containing the eluent and a phosphate solution from the composite material fixed bed;

and 4, adding magnesium chloride and ammonium chloride into the mixed solution containing the eluent and the phosphate solution to form magnesium ammonium phosphate precipitate, and flowing out the low-concentration eluent.

2. The method for enriching and separating phosphorus in the supernatant fluid of the anaerobic digestion of the sludge as claimed in claim 1, wherein the average pore diameter of the carrier of the composite material is 1-50 nm; the particle size of the metal particles is 2-55nm, and the weight percentage content of the metal particles in the composite material is controlled to be 3-25%.

3. The method for enriching and separating the phosphorus in the supernatant fluid of the anaerobic digestion of the sludge as claimed in claim 1 or 2, wherein in the step 2, the filtered supernatant fluid of the anaerobic digestion of the sludge is introduced into the composite material fixed bed at normal temperature and at the flow rate of 2-20 BV/h.

4. The method for enriching and separating phosphorus in the supernatant fluid of the anaerobic digestion of the sludge as claimed in claim 3, wherein the eluent is a NaOH-NaCl mixed solution with the mass fraction of 1-15%, and is introduced into the composite material fixed bed at the normal temperature under the flow condition of 0.5-4 BV/h.

5. The method for enriching and separating the phosphorus in the supernatant fluid of the anaerobic digestion of the sludge as claimed in claim 1 or 2, wherein the fixed composite material bed treated in the step 3 is washed to be neutral by 1-10% NaCl solution and distilled water in sequence.

6. The method for enriching and separating phosphorus in sludge anaerobic digestion supernatant fluid according to claim 1 or 2, characterized in that NaOH or NaCl solution is added to the low concentration eluent obtained in the step 4.

7. The method for enriching and separating phosphorus in the supernatant fluid of the anaerobic digestion of the sludge as claimed in claim 1 or 2, wherein in the step 1, the suspended substances in the supernatant fluid of the anaerobic digestion of the sludge are filtered by using a sand filter or a cloth filter, the flow rate of the sand filter or the cloth filter is 4-12m/h, and the concentration of suspended particulate matters in the effluent of the sand filter or the cloth filter is less than 5 mg/L.

Technical Field

The invention belongs to the technical field of sludge recycling, and particularly relates to a method for enriching and separating phosphorus in sludge anaerobic digestion supernatant.

Background

The biochemical treatment of sewage involves the anaerobic digestion process of sludge, in the anaerobic digestion of sludge, a large amount of phosphorus in the sludge is released into anaerobic digestion liquid, the phosphorus concentration in the supernatant fluid of the anaerobic digestion of sludge is higher, generally can reach more than 100mg/L, meanwhile, the organic matter concentration of the supernatant fluid of the anaerobic digestion of sludge is also relatively higher, generally more than 100mg/L, sometimes even reaches about 500mg/L (measured by COD). Phosphorus is one of the main elements for maintaining life in the earth system and is also the main element for causing water eutrophication. The presence of organic matters can increase the load of advanced sewage treatment to some extent, and can cause a plurality of adverse effects, such as: increasing the dosage of the medicament for the advanced treatment process; a large amount of disinfection byproducts are generated in the chlorination disinfection process; causing severe membrane fouling in membrane processing; the ion exchange method has the problems of reduced work exchange capacity, poor effluent quality, shortened operation period and the like caused by organic matter pollution of resin. Therefore, the method for effectively removing the phosphorus in the supernatant of the anaerobic digestion of the sludge and improving the performance of resisting organic pollution has very important significance for controlling water eutrophication caused by phosphorus pollution and recovering phosphorus resources.

At present, phosphate radicals are precipitated or crystallized in the forms of calcium phosphate, magnesium ammonium phosphate and the like by adding a calcium source, a magnesium source and the like in a precipitation method and a crystallization method, and the method has the main defects that an additional medicament is required to be added, so that the cost is high; in addition, the membrane separation technology can realize the synchronous removal of organic matters and phosphorus, but the cost and the investment are high, and the organic matters cause a series of problems such as membrane pollution. Compared with the method, the traditional ion exchange method is intensively shown in sewage with low-concentration phosphorus and organic matters in sewage dephosphorization research. The adopted resins all have the problems of organic pollution, competitive ion interference and the like, thereby leading to the reduction of the adsorption capacity. In addition, a method for treating phosphorus in the sludge anaerobic digestion solution by using special resin is adopted to obtain a high-concentration phosphate solution, the phosphorus exchange capacity in the research method is high, and the method is suitable for enrichment and separation of high-concentration phosphorus in water, but the pH value of the filtrate needs to be adjusted when the method is used, the affinity to phosphorus is not high enough, and the effect of organic pollution resistance is general.

Disclosure of Invention

The invention aims to provide a method for enriching and separating phosphorus in sludge anaerobic digestion supernatant, which aims to solve the problems that the adsorption capacity of phosphorus is not high enough, the pH value of sludge anaerobic digestion liquid needs to be adjusted, and organic pollution exists in the existing ion exchange method.

The invention adopts the following technical scheme: a method for enriching and separating phosphorus in sludge anaerobic digestion supernatant comprises the following steps:

step 1, filtering suspended matters in the supernatant of the anaerobic digestion of the sludge;

step 2, introducing the filtered sludge anaerobic digestion supernatant into a composite material fixed bed, and discharging effluent liquid after the composite material fixed bed adsorbs phosphorus; when the phosphorus concentration in the effluent liquid is 0.1-1mg/L, stopping introducing the supernatant liquid of the anaerobic digestion of the sludge into the composite material fixed bed;

wherein the composite material fixed bed is filled with a composite material, the composite material is an acrylic anion exchange resin loaded with metal particles, and the metal particles are any one of hydrated ferric oxide, hydrated zirconium oxide and hydrated lanthanum oxide nano particles;

step 3, after the step 2 is completed, introducing eluent into the composite material fixed bed, and discharging a mixed solution containing the eluent and a phosphate solution from the composite material fixed bed;

and 4, adding magnesium chloride and ammonium chloride into the mixed solution containing the eluent and the phosphate solution to form magnesium ammonium phosphate precipitate, and flowing out the low-concentration eluent.

Furthermore, the average pore diameter of the carrier of the composite material is 1-50 nm; the grain diameter of the metal particles is 2-55nm, and the weight percentage content of the metal particles in the composite material is controlled to be 3-25%.

Further, in the step 2, the filtered supernatant fluid of the anaerobic digestion of the sludge is introduced into the composite material fixed bed at the normal temperature at the flow rate of 2-20 BV/h.

Further, the eluent is a NaOH-NaCl mixed solution with the mass fraction of 1-15%, and is introduced into the composite material fixed bed at the flow rate of 0.5-4BV/h at normal temperature.

And further, washing the composite material fixed bed treated in the step 3 to be neutral by using 1-10% of NaCl solution and distilled water in sequence.

Further, NaOH or NaCl solution is added to the low concentration eluent obtained in the step 4.

Further, in the step 1, a sand filter or a cloth filter is used for filtering suspended matters in the supernatant of the anaerobic digestion of the sludge, the flow rate of the sand filter or the cloth filter is 4-12m/h, and the concentration of suspended particles in the effluent of the sand filter or the cloth filter is less than 5 mg/L.

The composite material prepared by passing the supernatant of the anaerobic digestion of the sludge through the composite material fixed bed made of the acrylic acid anion exchange resin loaded with the metal particles and loading the metal particles by utilizing the acrylic acid anion exchange resin has the advantages of high affinity to phosphorus, high adsorption selectivity, large adsorption capacity, no need of adjusting the pH value of filtrate and excellent organic pollution resistance, and is an ideal adsorption material for efficiently removing the phosphorus in the supernatant of the anaerobic digestion of the sludge.

Detailed Description

The present invention will be described in detail with reference to the following embodiments.

The invention provides a method for enriching and separating phosphorus in sludge anaerobic digestion supernatant, which comprises the following steps:

step 1, filtering suspended matters in the supernatant of the anaerobic digestion of the sludge;

step 2, introducing the filtered sludge anaerobic digestion supernatant into a composite material fixed bed, and discharging effluent liquid after the composite material fixed bed adsorbs phosphorus; when the concentration of phosphorus in the effluent liquid is 0.1-1mg/L, stopping introducing the sludge anaerobic digestion supernatant liquid into the composite material fixed bed; the flow rate of the pretreated sludge anaerobic digestion supernatant is 2-20 BV/h.

The composite material fixed bed is filled with a composite material, the composite material is an acrylic anion exchange resin loaded with metal particles, and the type of the composite material fixed bed specifically comprises: 213. d213, Purolite A860, Puropack PPA860S, Purolite A850, Purofine PFA850, Puropack PPA850, Purolite A850DL, Purolite A850S, AmberLite FPA58Cl, AmberLite FPA98 Cl, AmberLite HPR4580Cl, AmberLite HPR4780 Cl, AmberLite IRA458 Cl, AmberLite SCAV1, AmberLite SCAV2, AmberLite SCAV4 Cl, Aldex CRA, Aldex GCRA, Lewatit A8071, Lewatit S5128, Lewatit S5328, RESINTECH SBACR, SEPLITE SA458, SEPLITE MA 958. The metal particles are any one of hydrated iron oxide, hydrated zirconium oxide and hydrated lanthanum oxide nanoparticles.

And (2) directly passing the filtrate through the composite material fixed bed loaded with metal particles at normal temperature at the flow speed of 2-20BV/h without adjusting the pH of the filtrate, so that phosphorus in the sludge anaerobic digestion supernatant is effectively adsorbed, and the total phosphorus concentration in the effluent is greatly reduced.

Step 3, after the step 2 is completed, introducing eluent into the composite material fixed bed, and discharging a mixed solution containing the eluent and a phosphate solution from the composite material fixed bed;

and 4, adding magnesium chloride and ammonium chloride into the mixed solution containing the eluent and the phosphate solution to form magnesium ammonium phosphate precipitate, and flowing out the low-concentration eluent. In the phosphate solution of high-concentration phosphorus, magnesium chloride and ammonium chloride are added to precipitate phosphate in the form of magnesium ammonium phosphate (struvite), so that the aim of recovering phosphorus resources is fulfilled; and the residual low-concentration eluent is supplemented with NaOH or NaCl solution and is repeatedly used for elution operation, so that resource waste is avoided. The magnesium chloride and the ammonium chloride are added, the Mg/N/P molar concentration ratio needs to be adjusted to be 1.0, and the pH value is controlled to be about 9.5.

In some embodiments, the composite has a support average pore size of 1 to 50 nm; the particle size of the metal particles is 2-55nm, the weight percentage content of the metal particles in the composite material is controlled to be 3-25%, and the content is specifically calculated by Fe, Zr and La.

In some embodiments, in step 2, the filtered sludge anaerobic digestion supernatant is introduced into the composite material fixed bed at a flow rate of 2-20BV/h at normal temperature.

In some embodiments, the eluent is a mixed solution of NaOH and NaCl with the mass fraction of 1-15%, and is introduced into the composite material fixed bed adsorbing phosphorus in the step 2 at the flow rate of 0.5-4BV/h at normal temperature, so as to elute the phosphorus adsorbed on the fixed bed, thereby obtaining the phosphate solution containing high-concentration phosphorus.

In some embodiments, the composite material fixed bed treated in step 3 is washed to be neutral by 1-10% NaCl solution and distilled water in sequence for recycling.

In some embodiments, a NaOH or NaCl solution is added to the low concentration eluent obtained in step 4.

In some embodiments, in step 1, the suspended matter in the supernatant of the anaerobic digestion of the sludge is filtered by using a sand filter or a cloth filter, wherein the flow rate of the sand filter or the cloth filter is 4-12m/h, and the concentration of suspended particulate matters in the effluent of the sand filter or the cloth filter is less than 5 mg/L.

The method for enriching and separating the phosphorus in the supernatant of the anaerobic digestion of the sludge has strong affinity to the phosphorus and high adsorption selectivity, so that the adsorption capacity is large; the pH value of the filtrate is adjusted without adding extra medicament, and the pH range is wide (the pH value is 5-9); excellent organic pollution resistance, good elution effect and reusability.

The affinity of the ion exchange resin used by the existing ion exchange method to phosphorus is not strong enough, the adsorption selectivity to phosphorus is not high enough, so that the adsorption capacity is not high enough, the treatment capacity is relatively small, and the adsorption capacity is to be further improved. The common commercial resin is easily interfered by competitive ions, especially sulfate ions, when adsorbing and removing phosphorus, the adsorption capacity is small, and meanwhile, the resin exchange capacity is further reduced and the adsorption capacity is further reduced due to organic pollution; CN102964012A discloses that the styrene series polyethylene polyamine weak base anion exchange resin has polyamine group, and the oxygen atom on the monohydrogen phosphate or dihydrogen phosphate has strong affinity to phosphorus but not high enough adsorption capacity through hydrogen bond action with the hydrogen on the amine group. The metal particles and phosphorus in the method have stronger affinity under the complexing coordination action of phosphorus, are not easily interfered by other competitive ions, and have stronger affinity to phosphate radicals and higher adsorption selectivity compared with the hydrogen bond action, so that the adsorption capacity is further improved.

The pH value of the filtered sludge anaerobic digestion solution is not required to be adjusted before the conventional common commercial resin is introduced into the fixed bed, but the adsorption capacity is small; the large adsorption capacity requires adjustment of the pH of the filtrate, for example, the pH values disclosed in CN102964012A correspond to different phosphorus and organic matter concentrations (corresponding COD and total phosphorus concentrations of 100.7mg/L, 54.4mg/L, 320.4mg/L and 244.1mg/L, respectively, when the pH values are 7.02 and 8.35), so that addition of chemicals is indispensable for adjusting the pH of the filtrate, which increases the investment cost and complicates the operation. Compared with the existing ion exchange method, the method does not need to adjust the pH value of the filtered sludge anaerobic digestion supernatant when the composite material fixed bed is introduced, has wide pH range (the pH value is 5-9), and is simple to operate. When the pH is less than or equal to 9, the hydrated oxide exists in water mainly in the form of hydroxyl functional groups (FeOH, LaOH and ZrOH), and the surface hydroxyl functional groups are easy to form a coordination complex with phosphorus to form inner ring adsorption, so that strong affinity is formed for phosphorus, the pH range is wide, the investment cost is saved, and the operation is simple.

In the existing ion exchange method for removing phosphorus from sludge anaerobic digestion solution, ion exchange resins are styrene resins, resin frameworks are all hydrophobic structures, and the problem of organic pollution exists: most of organic matters in water are hydrophobic, styrene resin synthesized by aromatic hydrocarbon is also hydrophobic, the styrene resin and the aromatic hydrocarbon are firmly adsorbed together by strong molecular attraction, so that the strong physical adsorption effect of the resin on the organic matters is caused, and the problems that the common regeneration method is difficult to desorb, the elution effect is poor, the regeneration is difficult, the recycling efficiency is low and the like are solved; in contrast, CN102964012A discloses a method in which: styrene series polyethylene polyamine weak base anion exchange resin has the chemical stability of styrene series weak base resin and the high exchange capacity of acrylic acid series weak base resin, the resin framework is a styrene-acrylic acid double-framework structure, and the organic pollution resistance is better than that of the styrene series resin; but the organic contamination resistance is not sufficiently excellent. However, the carrier of the composite material loaded with metal particles used in the method for enriching and separating phosphorus in the supernatant fluid of anaerobic sludge digestion is acrylic acid anion exchange resin, and as the resin framework is of a hydrophilic structure (basically, aliphatic and few aromatic rings), the van der waals force is very weak, most organic matters in water are hydrophobic, the affinity to the organic matters is weak, and the organic matters are easy to elute and difficult to accumulate, the resin can effectively prevent pollution of natural organic matters, difficultly biodegradable organic matters, artificially synthesized organic matters and the like, has excellent organic matter pollution resistance and good elution effect, and is beneficial to long-term cyclic utilization.

Example 1

Taking supernatant of a sludge anaerobic digestion tank of a certain sewage treatment plant (the initial phosphorus concentration is 120mg/L, the initial COD is 150mg/L, and the initial sulfate radical concentration is 40mg/L), and filtering the supernatant of the sludge anaerobic digestion through a sand filter at the filtering speed of 4m/h to obtain filtered urban sludge anaerobic digestion liquid without adjusting the pH of the filtered urban sludge anaerobic digestion liquid. And introducing the filtered anaerobic digestion solution of the municipal sludge into 10mL of pretreated composite material fixed bed 213-Fe (213 loads nano metal particles Fe, the average pore diameter of the carrier is 3nm, the particle diameter of the nano metal particles is 2nm, and the weight percentage content of Fe is 8%) under the conditions of 25 ℃ and 4BV/h flow. The measured phosphorus concentration of the effluent meets the requirement of the discharge standard limit of the total phosphorus primary A in the discharge Standard of pollutants for municipal wastewater treatment plants (GB18918-2002), the maximum effluent volume is 280BV, the phosphorus concentration of the effluent is 0.1mg/L, and the exchange capacity for phosphorus is 33572mgP/L resin; the COD concentration of the effluent is 105mg/L, and the sulfate concentration is 32 mg/L.

Introducing a composite material fixed bed adsorbing phosphorus into a mixed solution of 1 percent NaOH and NaCl as an eluent at the normal temperature at the flow rate of 0.5BV/h, and eluting the phosphorus adsorbed on the fixed bed to obtain a phosphate solution containing high-concentration phosphorus; washing the composite material fixed bed after the phosphorus is eluted with 1% NaCl solution and distilled water in sequence until the composite material fixed bed is neutral for recycling; the phosphate solution of high-concentration phosphorus is precipitated in the form of magnesium ammonium phosphate (struvite) by adding magnesium chloride and ammonium chloride, so that the aim of recovering phosphorus resources is fulfilled; and after the residual low-concentration eluent is supplemented with NaOH or NaCl solution and repeatedly used for 3 times of elution operation, the removal efficiency of phosphorus is still over 95 percent, and the elution effect is good.

Example 2

Taking supernatant of a sludge anaerobic digestion tank of a certain sewage treatment plant (the initial phosphorus concentration is 120mg/L, the initial COD is 150mg/L, and the initial sulfate radical concentration is 40mg/L), and filtering the supernatant of the sludge anaerobic digestion through a sand filter at the filtering speed of 8m/h to obtain filtered urban sludge anaerobic digestion liquid without adjusting the pH of the filtered urban sludge anaerobic digestion liquid. And introducing 10mL of pretreated composite material fixed bed D213-Fe (D213 is loaded with nano metal particles Fe, the average pore diameter of the carrier is 35nm, the particle diameter of the nano metal particles is 33nm, and the weight percentage content of Fe is 15%) into the filtered urban sludge anaerobic digestion solution under the conditions of 25 ℃ and 2BV/h flow. The determination shows that the phosphorus concentration of the effluent meets the requirement of the discharge standard limit of the total phosphorus primary A in the discharge Standard of pollutants for municipal wastewater treatment plants (GB18918-2002), the maximum effluent volume is 300BV, the phosphorus concentration of the effluent is 1mg/L, and the exchange capacity for phosphorus is 35700mgP/L resin; the COD concentration of the effluent is 105mg/L, and the sulfate concentration is 32 mg/L.

Introducing a composite material fixed bed adsorbing phosphorus into a 5% NaOH-NaCl mixed solution as an eluent at the flow rate of 1BV/h at normal temperature, and eluting the phosphorus adsorbed on the fixed bed to obtain a phosphate solution containing high-concentration phosphorus; washing the composite material fixed bed after the phosphorus is eluted with 2 percent NaCl solution and distilled water in sequence until the composite material fixed bed is neutral for recycling; the phosphate solution of high-concentration phosphorus is precipitated in the form of magnesium ammonium phosphate (struvite) by adding magnesium chloride and ammonium chloride, so that the aim of recovering phosphorus resources is fulfilled; and after the residual low-concentration eluent is supplemented with NaOH or NaCl solution and repeatedly used for 3 times of elution operation, the removal efficiency of phosphorus is still over 95 percent, and the elution effect is good.

Example 3

Taking supernatant of a sludge anaerobic digestion tank of a certain sewage treatment plant (the initial phosphorus concentration is 180mg/L, the initial COD is 150mg/L, and the initial sulfate radical concentration is 50mg/L), and filtering the supernatant of the sludge anaerobic digestion through a sand filter at the filtering speed of 8m/h to obtain filtered urban sludge anaerobic digestion liquid without adjusting the pH of the filtered urban sludge anaerobic digestion liquid. And introducing 10mL of pretreated composite material fixed bed Purolite A860-La (the Purolite A860 loads nano metal particles La, the average pore diameter of the carrier is 30nm, the particle diameter of the nano metal particles is 28nm, and the weight percentage content of the La is 20%) into the filtered urban sludge anaerobic digestion solution under the conditions of 25 ℃ and 10BV/h flow. The determination shows that the phosphorus concentration of the effluent meets the requirement of the discharge standard limit of the primary A of total phosphorus in the discharge Standard of pollutants for municipal wastewater treatment plants (GB18918-2002), the maximum effluent volume is 250BV, the phosphorus concentration of the effluent is 0.5mg/L, and the exchange capacity for phosphorus is 44875mgP/L resin; the COD concentration of the effluent is 105mg/L, and the sulfate radical concentration is 40 mg/L.

Using 10% NaOH-NaCl mixed solution as eluent, introducing a composite material fixed bed adsorbing phosphorus at the normal temperature under the flow condition of 2BV/h, and eluting the phosphorus adsorbed on the fixed bed to obtain phosphate solution containing high-concentration phosphorus; washing the composite material fixed bed after the phosphorus is eluted with 5 percent NaCl solution and distilled water in sequence until the composite material fixed bed is neutral for recycling; the phosphate solution of high-concentration phosphorus is precipitated in the form of magnesium ammonium phosphate (struvite) by adding magnesium chloride and ammonium chloride, so that the aim of recovering phosphorus resources is fulfilled; and after the residual low-concentration eluent is supplemented with NaOH or NaCl solution and repeatedly used for 3 times of elution operation, the removal efficiency of phosphorus is still over 95 percent, and the elution effect is good.

Example 4

Taking supernatant of a sludge anaerobic digestion tank of a certain sewage treatment plant (the initial phosphorus concentration is 180mg/L, the initial COD is 150mg/L, and the initial sulfate radical concentration is 50mg/L), and filtering the supernatant of the sludge anaerobic digestion through a sand filter at the filtering speed of 12m/h to obtain filtered urban sludge anaerobic digestion liquid without adjusting the pH of the filtered urban sludge anaerobic digestion liquid. And (2) introducing 10mL of pretreated composite material fixed bed AmberLite FPA58 Cl-La (the AmberLite FPA58Cl is loaded with nano metal particles La, the average pore diameter of the carrier is 1.5nm, the particle diameter of the nano metal particles is 2nm, and the weight percentage content of the La is 5%) into the filtered urban sludge anaerobic digestion solution at the temperature of 25 ℃ and the flow rate of 20 BV/h. The determination shows that the phosphorus concentration of the effluent meets the requirement of the discharge standard limit of the primary A of total phosphorus in the discharge Standard of pollutants for municipal wastewater treatment plants (GB18918-2002), the maximum effluent volume is 200BV, the phosphorus concentration of the effluent is 0.1mg/L, and the exchange capacity for phosphorus is 35980mgP/L resin; the COD concentration of the effluent is 105mg/L, and the sulfate radical concentration is 40 mg/L.

Using 15% NaOH-NaCl mixed solution as eluent, introducing a composite material fixed bed adsorbing phosphorus at the normal temperature under the flow condition of 4BV/h, and eluting the phosphorus adsorbed on the fixed bed to obtain phosphate solution containing high-concentration phosphorus; washing the composite material fixed bed after the phosphorus is eluted with 10% NaCl solution and distilled water in sequence until the composite material fixed bed is neutral for recycling; the phosphate solution of high-concentration phosphorus is precipitated in the form of magnesium ammonium phosphate (struvite) by adding magnesium chloride and ammonium chloride, so that the aim of recovering phosphorus resources is fulfilled; and after the residual low-concentration eluent is supplemented with NaOH or NaCl solution and repeatedly used for 3 times of elution operation, the removal efficiency of phosphorus is still over 95 percent, and the elution effect is good.

Example 5

Taking supernatant of a sludge anaerobic digestion tank of a certain sewage treatment plant (the initial phosphorus concentration is 210mg/L, the initial COD is 100mg/L, and the initial sulfate radical concentration is 40mg/L), and filtering the supernatant of the sludge anaerobic digestion through a sand filter at the filtering speed of 4m/h to obtain filtered urban sludge anaerobic digestion liquid without adjusting the pH of the filtered urban sludge anaerobic digestion liquid. And (2) introducing 10mL of pretreated composite material fixed bed Aldex CRA-Zr (nanometer metal particles Zr are loaded on the Aldex CRA, the average pore diameter of the carrier is 45nm, the particle diameter of the nanometer metal particles is 43nm, and the weight percentage content of La is 25%) into the filtered urban sludge anaerobic digestion solution at the temperature of 25 ℃ and the flow rate of 2 BV/h. The determination shows that the maximum effluent volume of which the phosphorus concentration of the effluent meets the requirement of the total phosphorus primary A discharge standard limit in the discharge Standard of pollutants for municipal wastewater treatment plants (GB18918-2002) is 280BV, the phosphorus concentration of the effluent is 1mg/L, and the exchange capacity of the effluent for phosphorus is 58520mgP/L resin; the COD concentration of the effluent is 70mg/L, and the sulfate concentration is 32 mg/L.

Introducing a composite material fixed bed adsorbing phosphorus into a mixed solution of 1 percent NaOH and NaCl as an eluent at the normal temperature at the flow rate of 0.5BV/h, and eluting the phosphorus adsorbed on the fixed bed to obtain a phosphate solution containing high-concentration phosphorus; washing the composite material fixed bed after the phosphorus is eluted with 1% NaCl solution and distilled water in sequence until the composite material fixed bed is neutral for recycling; the phosphate solution of high-concentration phosphorus is precipitated in the form of magnesium ammonium phosphate (struvite) by adding magnesium chloride and ammonium chloride, so that the aim of recovering phosphorus resources is fulfilled; and after the residual low-concentration eluent is supplemented with NaOH or NaCl solution and repeatedly used for 3 times of elution operation, the removal efficiency of phosphorus is still over 95 percent, and the elution effect is good.

Example 6

Taking supernatant of a sludge anaerobic digestion tank of a certain sewage treatment plant (the initial phosphorus concentration is 210mg/L, the initial COD is 100mg/L, and the initial sulfate radical concentration is 40mg/L), and filtering the supernatant of the sludge anaerobic digestion through a sand filter at the filtering speed of 12m/h to obtain filtered urban sludge anaerobic digestion liquid without adjusting the pH of the filtered urban sludge anaerobic digestion liquid. And (2) introducing 10mL of pretreated composite material fixed bed Lewatit A8071-Zr into the filtered urban sludge anaerobic digestion solution at the temperature of 25 ℃ and the flow rate of 20BV/h (Lewatit A8071 loads nano metal particles Zr, the average pore diameter of a carrier is 5nm, the particle diameter of the nano metal particles is 4nm, and the weight percentage content of La is 10%). The determination shows that the phosphorus concentration of the effluent meets the requirement of the discharge standard limit of the primary A of total phosphorus in the discharge Standard of pollutants for municipal wastewater treatment plants (GB18918-2002), the maximum effluent volume is 200BV, the phosphorus concentration of the effluent is 0.5mg/L, and the exchange capacity for phosphorus is 41900mgP/L resin; the COD concentration of the effluent is 70mg/L, and the sulfate concentration is 32 mg/L.

Using 15% NaOH-NaCl mixed solution as eluent, introducing a composite material fixed bed adsorbing phosphorus at the normal temperature under the flow condition of 4BV/h, and eluting the phosphorus adsorbed on the fixed bed to obtain phosphate solution containing high-concentration phosphorus; washing the composite material fixed bed after the phosphorus is eluted with 10% NaCl solution and distilled water in sequence until the composite material fixed bed is neutral for recycling; the phosphate solution of high-concentration phosphorus is precipitated in the form of magnesium ammonium phosphate (struvite) by adding magnesium chloride and ammonium chloride, so that the aim of recovering phosphorus resources is fulfilled; and after the residual low-concentration eluent is supplemented with NaOH or NaCl solution and repeatedly used for 3 times of elution operation, the removal efficiency of phosphorus is still over 95 percent, and the elution effect is good.

Comparative example 1

The D213 product of Jiangsu Suqing water treatment engineering group Limited company is used for treating the supernatant fluid of anaerobic digestion of sludge, and the water quality conditions are as follows: the initial phosphorus concentration was 120mg/L, the initial COD concentration was 150mg/L and the initial sulfate concentration was 40 mg/L. Filtering the sludge anaerobic digestion supernatant through a sand filter at a filtering speed of 8m/h to obtain filtered urban sludge anaerobic digestion liquid, and adjusting the pH of the filtered urban sludge anaerobic digestion liquid to 7.0. And introducing the filtered anaerobic digestion solution of the municipal sludge into a 10mL pretreated D213 fixed bed at the temperature of 25 ℃ and the flow rate of 2 BV/h. The determination shows that the phosphorus concentration of the effluent meets the requirement of the discharge standard limit of the primary A of total phosphorus in the discharge Standard of pollutants for municipal wastewater treatment plants (GB18918-2002), the maximum effluent volume is 80BV, the phosphorus concentration of the effluent is 1mg/L, and the exchange capacity for phosphorus is 9520mgP/L resin; the COD concentration of the effluent is 105mg/L, and the sulfate concentration is 32 mg/L.

Comparative example 2

The SQD-96 product of Jiangsu Suqing water treatment engineering group Limited is used for treating the supernatant fluid of anaerobic digestion of sludge. The water quality conditions are as follows: and filtering the supernatant of anaerobic sludge digestion at a filtering speed of 8m/h by using a sand filter under the conditions that the initial phosphorus concentration is 120mg/L, the initial COD (chemical oxygen demand) is 150mg/L and the initial sulfate radical concentration is 40mg/L to obtain filtered anaerobic sludge digestion liquid, and adjusting the pH of the filtered anaerobic sludge digestion liquid to be 5.0. Introducing filtered anaerobic digestion solution of the municipal sludge into a 10mL pretreated SQD-96 resin bed under the conditions of 25 ℃ and 2BV/h flow, and determining that the phosphorus concentration of effluent liquid meets the requirement of the discharge standard limit value of the total phosphorus first-grade A in discharge Standard of pollutants for municipal wastewater treatment plants (GB18918-2002) that the maximum effluent liquid volume is 96BV and the exchange capacity for phosphorus is only 11424mgP/L resin; the COD concentration of the effluent is 118mg/L, and the sulfate concentration is 28 mg/L.

Comparing the comparative example 1 and the comparative example 2 with the example 2 respectively, it can be seen that under the condition of the same water quality, the method of the invention utilizes the composite material loaded with the nano metal particles to treat the supernatant fluid of anaerobic digestion of sludge, and the selectivity of phosphate is greatly improved; the method of the invention has the phosphorus exchange capacity reaching 35700mgP/L resin, which is more than 3 times of the phosphorus exchange capacity in the prior art, greatly improves the phosphorus exchange capacity, has large treatment capacity, and is particularly suitable for enriching and separating the phosphorus with higher concentration in the sewage. Meanwhile, the method does not need to adjust filtered urban sludge anaerobic digestion liquid, has excellent organic pollution resistance and elution effect, and is beneficial to long-term recycling.

The metal particles and phosphorus in the method have stronger affinity under the complexing coordination action of phosphorus, are not easily interfered by other competitive ions, and have stronger affinity to phosphate radicals and higher adsorption selectivity compared with the hydrogen bond action, so that the adsorption capacity is further improved. Meanwhile, the method does not need to adjust the pH value of the filtered sludge anaerobic digestion supernatant when the composite material fixed bed is introduced, the pH range is wide (the pH value is 5-9), and the operation is simple. In addition, the carrier of the composite material loaded with the metal particles used in the method is acrylic acid anion exchange resin, and the resin framework is a hydrophilic structure (basically, aliphatic and aromatic rings are few), the Van der Waals force is very weak, most organic matters in water are hydrophobic, the affinity to the organic matters is weak, and the elution is easy to realize, so that the organic matters are difficult to accumulate, therefore, the resin can effectively prevent the pollution of natural organic matters, difficultly biodegradable organic matters, artificially synthesized organic matters and the like, has excellent organic matter pollution resistance, has good elution effect, and is beneficial to long-term cyclic utilization.

The composite material prepared by passing the supernatant of anaerobic digestion of sludge through the composite material fixed bed prepared by the acrylic acid anion exchange resin loaded with the metal particles and loading the metal particles by utilizing the acrylic acid anion exchange resin has the advantages of high affinity, high adsorption selectivity, large adsorption capacity, no need of adjusting the pH value of filtrate and excellent organic pollution resistance, and is an ideal adsorption material for efficiently removing phosphorus in the supernatant of anaerobic digestion of sludge.