A method for preparing anaerobic granular sludge crystal nuclei using excess sludge

Abstract

The present invention discloses a method for preparing anaerobic granular sludge crystal nuclei by using excess sludge, which comprises the following steps: ozone is introduced into the excess sludge liquid to fully crack the sludge and release proteins and polysaccharides, obtaining a suspension; the suspension is allowed to stand and stratified to separate the supernatant, and the pH of the supernatant is adjusted to 6-10 by carbide slag to obtain a first solution with free ammonium ions and phosphate ions; MgCl2 is added to the first solution to react with ammonium ions and phosphate ions to generate magnesium ammonium phosphate and calcium phosphate coprecipitation, the coprecipitation is separated, and the remaining solution is used as a second solution; the coprecipitation is soaked in a glutaraldehyde solution, taken out and put into the second solution to obtain a coprecipitation attached with proteins and polysaccharides, and the coprecipitation attached with proteins and polysaccharides is separated; the coprecipitation attached with proteins and polysaccharides is washed with water, dried and calcined to prepare anaerobic granular sludge crystal nuclei. The crystal nuclei prepared by the above method can be used for anaerobic granular sludge cultivation to recycle the excess sludge.

Description

Technical Field

[0001] The present invention belongs to the field of sewage treatment, and particularly relates to a method for preparing anaerobic granular sludge crystal nuclei by using excess sludge. Background Art

[0002] With the rapid development of industry and the remarkable improvement of people's living standards, the concomitant is a large increase in industrial and domestic sewage. If not treated in time, it often has a significant impact on the environment, which is a common problem both at home and abroad. How to correctly and effectively treat sewage and follow the concept of sustainable economic development to maximize resource utilization rate is the focus of research by scholars at home and abroad.

[0003] Sewage treatment is generally divided into physical method, biological method and chemical method. The physical method is commonly used for sewage with low requirements for sewage treatment degree. The chemical method is commonly used for industrial sewage, with remarkable treatment effect but high cost, and is generally used for the subsequent treatment of the biological method. The biological method uses the metabolic function of microorganisms to decompose and oxidize organic substances in sewage into stable inorganic substances. This method has high efficiency and controllable cost.

[0004] The anaerobic granular sludge method for sewage treatment is a widely used sewage treatment method at home and abroad. Due to the wide use of this method, the generation amount of excess sludge has increased greatly. For the treatment of excess sludge, incineration or landfill is usually used, which may cause greater environmental pollution, and at the same time, resources cannot be reasonably utilized and the cost also rises significantly. Summary of the Invention

[0005] In order to solve the problem that excess sludge cannot be recycled and sustainably reused, the present invention provides a method for preparing anaerobic granular sludge crystal nuclei by using excess sludge. Through this method, excess sludge can be turned into anaerobic granular sludge crystal nuclei, which can not only effectively utilize the excess sludge resources, but also utilize the good biocompatible adsorption property of the crystal nuclei when culturing anaerobic granular sludge to control the escape of particles and strengthen the forming speed of granular sludge.

[0006] The method for preparing anaerobic granular sludge crystal nuclei by using excess sludge according to the present invention includes the following steps:

[0007] (1) Introduce ozone into the excess sludge liquid to fully crack the sludge and release proteins and polysaccharides, obtaining a sludge suspension;

[0008] (2) Let the sludge suspension stand and stratify to separate the supernatant, and adjust the pH of the supernatant to 6 - 10 with carbide slag, obtaining a first solution with free ammonium ions and phosphate ions;

[0009] (3) Add MgCl2 to the first solution to react with ammonium ions and phosphate ions to generate magnesium ammonium phosphate and calcium phosphate coprecipitation, and separate the coprecipitation. The remaining solution is used as the second solution;

[0010] (4) Immerse the coprecipitate in a glutaraldehyde solution for 2 - 6 h, then take out the coprecipitate and put it into the second solution to obtain a coprecipitate attached with protein and polysaccharide, and separate the coprecipitate attached with protein and polysaccharide;

[0011] (5) Wash, dry, and calcine the coprecipitate attached with protein and polysaccharide to prepare magnesium ammonium phosphate / calcium phosphate coprecipitate particles with surface carbonization, namely the anaerobic granule sludge crystal nucleus.

[0012] In step (1), the excess sludge used is the excess sludge with a compact zoogloea structure, the concentration of the sludge suspension is 10 - 15 g / L; the volume percentage concentration of ozone is 20 - 30%, the feeding rate is 4 - 8 L / h, the cracking temperature is 25 °C; the cracking time is 30 - 35 min.

[0013] In step (2), the carbide slag is a waste residue mainly composed of calcium hydroxide, the initial pH value of the supernatant is about 6, and the pH is adjusted to alkaline by the carbide slag.

[0014] In step (3), before adding MgCl2, add ammonium salt and phosphate in the first solution to make the molar ratio NH4 + :PO4 3- = 1:1, and slowly add MgCl2 according to the molar ratio Mg 2+ :NH4 + :PO4 3- = 1 - 1.5:1:1, and the reaction temperature is 25 °C. The above ammonium salt is preferably NH4Cl, and the phosphate is preferably KH2PO4.

[0015] In step (4), the mass percentage concentration of the glutaraldehyde solution is 2%. After soaking in the glutaraldehyde solution, the glutaraldehyde can fully wrap the precipitate, improving the binding amount of the precipitate to protein and polysaccharide.

[0016] In step (5), the washing is carried out with distilled water; the drying is carried out in a vacuum drying oven at 80 °C for 20 - 30 h; the calcination is carried out in a muffle furnace under nitrogen protection, with a heating rate of 5 °C / min, heating to 500 - 700 °C, and maintaining at this temperature for 3 - 5 h.

[0017] The present invention also provides an anaerobic granule sludge crystal nucleus prepared by the above preparation method.

[0018] The present invention also provides the application of the above anaerobic granule sludge crystal nucleus in culturing anaerobic granule sludge.

[0019] Beneficial effects: The present invention reuses the surplus sludge resources to prepare anaerobic granular sludge crystal nuclei, and at the same time uses these granules as crystal nuclei for anaerobic granular sludge cultivation. They have both good biocompatible adsorption properties and appropriate specific gravity, which can control the escape of the granules and strengthen the forming speed of granular sludge. Specific embodiments

[0020] The technical solutions of the present invention will be described in detail below through embodiments, but the protection scope of the present invention is not limited to the described embodiments.

[0021] Example 1

[0022] (1) Take 1 L of surplus sludge liquid with a concentration of 10 g / L and place it in a beaker. The sludge floc structure is compact. At a room temperature of 25 °C, ozone with a volume percentage concentration of 20% is introduced at a rate of 4 L / h for 35 min to fully crack the sludge and release proteins and polysaccharides, obtaining a suspension.

[0023] (2) Pour the above suspension into a separatory funnel and let it stand for stratification to separate the supernatant. Add 2 g of carbide slag mainly composed of calcium hydroxide to the supernatant to adjust the pH to 10, obtaining a first solution with free ammonium ions and phosphate ions, and detect the concentrations of ammonium ions and phosphate ions in the first solution.

[0024] (3) At 25 °C, add appropriate amounts of NH4Cl and KH2PO4 to the first solution to make the molar ratio NH4 + : PO4 3- = 1:1, and then slowly add 2 g of MgCl2 according to the molar ratio Mg 2+ : NH4 + : PO4 3- = 1:1:1. Magnesium ions react with ammonium ions and phosphate ions under alkaline conditions to form a coprecipitate of magnesium ammonium phosphate (commonly known as "struvite") and calcium phosphate, and separate the coprecipitate. The remaining solution is used as the second solution.

[0025] (4) Immerse the above coprecipitate in a glutaraldehyde solution with a mass percentage concentration of 2% for 2.5 h, then take it out and put it into the second solution to obtain a coprecipitate attached with proteins and polysaccharides, and separate the coprecipitate attached with proteins and polysaccharides.

[0026] (5) Wash the coprecipitate attached with proteins and polysaccharides with distilled water until the pH is neutral, dry it in a vacuum drying oven at 80 °C for 20 h, and finally, in a nitrogen atmosphere, heat it up to 500 °C at a heating rate of 5 °C / min and calcine it at this temperature for 3.5 h to obtain a surface-carbonized magnesium ammonium phosphate / calcium phosphate coprecipitate granule, which is the anaerobic granular sludge crystal nucleus.

[0027] Example 2

[0028] (1) Take 1 L of the residual sludge liquid with a concentration of 12 g / L and place it in a beaker. The sludge floc structure is compact. At a room temperature of 25 °C, ozone with a concentration of 22% is introduced at a rate of 5 L / h for 34 min to fully crack the sludge and release proteins and polysaccharides, obtaining a suspension.

[0029] (2) Pour the above suspension into a separating funnel and let it stand for stratification to separate the supernatant. Add 2 g of carbide slag mainly composed of calcium hydroxide to the supernatant to adjust the pH to 10, obtaining a first solution with free ammonium and phosphate ions, and detect the concentrations of ammonium and phosphate ions in the first solution.

[0030] (3) At 25 °C, add appropriate amounts of NH4Cl and KH2PO4 to the first solution to make the molar ratio NH4 + :PO4 3- = 1:1, and then slowly add 3 g of MgCl2 according to the molar ratio Mg 2+ :NH4 + :PO4 3- = 1.2:1:1. Magnesium ions react with ammonium and phosphate ions under alkaline conditions to form magnesium ammonium phosphate (commonly known as "struvite") and calcium phosphate coprecipitation, and separate the coprecipitation. The remaining solution is used as the second solution.

[0031] (4) Immerse the above coprecipitation in a 2% glutaraldehyde solution for 3.5 h, then take it out and put it into the second solution to obtain a coprecipitation attached with proteins and polysaccharides, and separate the coprecipitation attached with proteins and polysaccharides.

[0032] (5) Wash the coprecipitation attached with proteins and polysaccharides with distilled water until the pH is neutral, dry it in a vacuum drying oven at 80 °C for 24 h, and finally heat it to 600 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and calcine it at this temperature for 4 h to obtain magnesium ammonium phosphate / calcium phosphate coprecipitation particles with surface carbonization, which are the anaerobic granular sludge crystal nuclei.

[0033] Example 3

[0034] (1) Take 1 L of the residual sludge liquid with a concentration of 14 g / L and place it in a beaker. The sludge floc structure is compact. At a room temperature of 25 °C, ozone with a concentration of 25% is introduced at a rate of 6 L / h for 32 min to fully crack the sludge and release proteins and polysaccharides, obtaining a suspension.

[0035] (2) Pour the above suspension into a separating funnel and let it stand for stratification to separate the supernatant. Add 2 g of carbide slag mainly composed of calcium hydroxide to the supernatant to adjust the pH to 10, obtaining a first solution with free ammonium and phosphate ions, and detect the concentrations of ammonium and phosphate ions in the first solution.

[0036] (3) At 25 °C, appropriate amounts of NH4Cl and KH2PO4 were added to the first solution to make the molar ratio NH4 + :PO4 3- = 1:1, and then 4 g of MgCl2 was slowly added according to the molar ratio of Mg 2+ :NH4 + :PO4 3- = 1.4:1:1. The magnesium ions reacted with ammonium and phosphate ions under alkaline conditions to form a coprecipitate of magnesium ammonium phosphate (commonly known as "struvite") and calcium phosphate, and the coprecipitate was separated. The remaining solution was used as the second solution.

[0037] (4) The above coprecipitate was soaked in a 2% glutaraldehyde solution for 4.5 h, then taken out and put into the second solution to obtain a coprecipitate attached with proteins and polysaccharides, and the coprecipitate attached with proteins and polysaccharides was separated.

[0038] (5) The coprecipitate attached with proteins and polysaccharides was washed with distilled water until the pH was neutral, dried in a vacuum drying oven at 80 °C for 28 h, and finally heated to 650 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and calcined at this temperature for 4.5 h to obtain magnesium ammonium phosphate / calcium phosphate coprecipitate particles with surface carbonization, which were the anaerobic granular sludge crystal nuclei.

[0039] Example 4

[0040] (1) 1 L of the residual sludge solution with a concentration of 15 g / L was taken and placed in a beaker. The sludge zoogloea structure was compact. At a room temperature of 25 °C, ozone with a concentration of 30% was introduced at a rate of 7 L / h for 30 min to fully break down the sludge and release proteins and polysaccharides, obtaining a suspension.

[0041] (2) The above suspension was loaded into a separating funnel and allowed to stand for stratification, and the supernatant was separated. 2 g of carbide slag mainly composed of calcium hydroxide was added to the supernatant to adjust the pH to 10, obtaining a first solution with free ammonium and phosphate ions, and the concentrations of ammonium and phosphate ions in the first solution were detected.

[0042] (3) At 25 °C, appropriate amounts of NH4Cl and KH2PO4 were added to the first solution to make the molar ratio NH4 + :PO4 3- = 1:1, and then 4.5 g of MgCl2 was slowly added according to the molar ratio of Mg 2+ :NH4 + :PO4 3- = 1.5:1:1. The magnesium ions reacted with ammonium and phosphate ions under alkaline conditions to form a coprecipitate of magnesium ammonium phosphate (commonly known as "struvite") and calcium phosphate, and the coprecipitate was separated. The remaining solution was used as the second solution.

[0043] (4) Immerse the above coprecipitate in a 2% glutaraldehyde solution for 5.5 h, then take it out and put it into the second solution to obtain a coprecipitate attached with proteins and polysaccharides, and separate the coprecipitate attached with proteins and polysaccharides.

[0044] (5) Wash the above coprecipitate attached with proteins and polysaccharides with distilled water until the pH is neutral, dry it in a vacuum drying oven at 80 °C for 30 h, and finally heat it to 700 °C at a heating rate of 5 °C / min in a nitrogen atmosphere and calcine it at this temperature for 5 h to obtain magnesium ammonium phosphate / calcium phosphate coprecipitate particles with surface carbonization, which are the crystal nuclei of anaerobic granular sludge.

[0045] The crystal nuclei of anaerobic granular sludge obtained in the present invention can be used as crystal nuclei for culturing anaerobic granular sludge. They not only have good biocompatible adsorption, but also have an appropriate specific gravity, which can control the escape of particles and enhance the forming speed of granular sludge.

[0046] For the technologies not specifically mentioned above, refer to the prior art.

[0047] As described above, although the present invention has been shown and described with reference to specific preferred embodiments, it should not be construed as a limitation of the present invention itself. Various changes can be made in its form and details without departing from the spirit and scope of the present invention defined by the appended claims.

Claims

1. A method for preparing anaerobic granular sludge crystal nuclei using excess sludge, characterized in that, It includes the following steps: (1) Introduce ozone into the excess sludge liquid to fully crack the sludge and release proteins and polysaccharides, obtaining a sludge suspension; the excess sludge used is the excess sludge with a tightly structured zoogloea, and the concentration of the sludge suspension is 10 - 15 g / L; the volume percentage concentration of ozone is 20 - 30%, the introduction rate is 4 - 8 L / h, the cracking temperature is 25 °C; the cracking time is 30 - 35 min; (2) Let the sludge suspension stand and separate into supernatant, and adjust the pH of the supernatant to 6 - 10 with carbide slag to obtain a first solution with free ammonium ions and phosphate ions; (3) Add MgCl2 into the first solution to react with ammonium ions and phosphate ions to form a coprecipitate of magnesium ammonium phosphate and calcium phosphate, and separate the coprecipitate, and the remaining solution is used as the second solution; (4) Immerse the coprecipitate in a glutaraldehyde solution for 2 - 6 h, then take out the coprecipitate and put it into the second solution to obtain a coprecipitate attached with proteins and polysaccharides, and separate the coprecipitate attached with proteins and polysaccharides; (5) Wash, dry, and calcine the coprecipitate attached with proteins and polysaccharides to prepare magnesium ammonium phosphate / calcium phosphate coprecipitate particles with surface carbonization, that is, the anaerobic granule sludge crystal nucleus.

2. The method for preparing anaerobic granular sludge crystal nuclei using excess sludge according to claim 1, characterized in that In step (2), the carbide slag is a waste residue mainly composed of calcium hydroxide.

3. The method for preparing anaerobic granular sludge crystal nuclei using excess sludge according to claim 1, characterized in that, In step (3), before adding MgCl2, ammonium salts and phosphates are added to the first solution to make the molar ratio of NH4 + :PO4 3- =1:1, and Mg is added slowly according to the molar ratio of Mg 2+ :NH4 + :PO4 3- =1 - 1.5:1:1, and the reaction temperature is 25°C.

4. The method for preparing anaerobic granular sludge crystal nuclei using excess sludge according to claim 3, characterized in that, The ammonium salt is NH4Cl, and the phosphate is KH2PO4.

5. The method for preparing anaerobic granular sludge crystal nuclei by using excess sludge according to claim 1, characterized in that, In step (4), the mass percentage concentration of the glutaraldehyde solution is 2%.

6. The method for preparing anaerobic granular sludge crystal nuclei using excess sludge according to claim 1, characterized in that, In step (5), the washing is carried out with distilled water; the drying is carried out in a vacuum drying oven at 80 °C for 20 - 30 h; the calcination is carried out in a muffle furnace under nitrogen protection, with a heating rate of 5 °C / min, heating to 500 - 700 °C, and maintaining at this temperature for 3 - 5 h.

7. An anaerobic granule sludge crystal nucleus prepared by using the method described in any one of claims 1 - 6.

8. The application of the anaerobic granule sludge crystal nucleus described in claim 7 in cultivating anaerobic granule sludge.