A carbon source material for microbial culture and its preparation method

Abstract

The invention discloses a method for preparing a carbon source material for microbial culture, comprising the following steps: after mixing gelatin with oxalic acid, stirring evenly at room temperature, then adding concentrated sulfuric acid with a concentration of 70 80wt% to the mixture to react, slowly dropping while stirring during the addition process, cooling the product to room temperature after completion of the dropwise addition, then washing and drying the product to obtain a carbon source precursor material; the obtained carbon source precursor material is immersed in an ethanol solution of fluorinated silane overnight, then washed and sintered, the obtained product is ground into powder and then added with trace elements and vitamins to mix evenly; the above-mentioned mixed material is added to a twin-screw extruder, extruded after heating and melting, extrusion end blowing 5 15L / L min, extrusion die hole diameter 1 5cm, and the extrusion material is cooled and cut into a length of 1 10cm to obtain a slow-release carbon source filler. The carbon source material obtained by the method of the present invention can effectively improve the total nitrogen removal rate during denitrification.

Description

Technical Field

[0001] The invention belongs to the technical field of microbial cultivation, and in particular relates to a carbon source material for microbial cultivation and a preparation method thereof. Background Art

[0002] A general term for all tiny organisms that are difficult to see with the naked eye and can only be observed with the help of an optical microscope or an electron microscope. Microorganisms include bacteria, viruses, fungi, and a few algae. (But some microorganisms can be seen with the naked eye, such as mushrooms and Ganoderma lucidum, which belong to fungi.) Viruses are a type of "non-cellular organisms" composed of a few components such as nucleic acids and proteins, but their survival depends on living cells. According to the different environments in which they exist, they are divided into space microorganisms, marine microorganisms, etc., and according to the cell structure, they are divided into prokaryotic microorganisms and eukaryotic microorganisms.

[0003] In the process of sewage treatment, denitrification by denitrifying microorganisms can convert nitrate nitrogen into nitrogen gas under anoxic conditions, which overflows the water surface and is released into the atmosphere, participating in the natural nitrogen cycle, greatly reducing nitrogen-containing substances in the water, and reducing the potential danger of effluent, thus achieving the purpose of removing nitrogen from wastewater. At present, denitrification is mainly limited by the following factors: (1) insufficient carbon source; (2) easy clogging, small specific surface area of ​​microbial carrier; (3) insufficient number of denitrifying bacteria. Therefore, it is usually necessary to supplement carbon source in the sewage treatment process.

[0004] In order to improve the denitrification efficiency, CN111362416A discloses a slow-release carbon source filler and a preparation method thereof. The slow-release carbon source filler comprises the following ingredients in parts by weight: 20-50 parts of micro-carbonized fiber, 40-60 parts of polyethylene terephthalate, 10-15 parts of iron ore powder, 5-10 parts of carbon nanotubes, 5-10 parts of diatomaceous earth, 1-10 parts of a compatibilizer, and 1-10 parts of a lubricant. CN107935202B discloses a biodegradable slow-release carbon source filler and a preparation method thereof. The slow-release carbon source filler consists of an external carbon source layer, an internal carbon source layer, and a connecting colloid. The external carbon source layer mainly includes a biodegradable polymer, starch, and an emulsifier; the internal carbon source layer mainly includes agar powder, oat bran powder, microbial nutrients, xanthan gum, and trehalose; the connecting colloid mainly includes carbon nanotubes, polyvinyl pyrrolidone, and methyl cellulose. Based on the traditional method of preparing a slow-release carbon source by blending starch and a biodegradable polymer as a basic system, the present invention prepares the external carbon source into powder, and wraps the internal carbon source in multiple layers through a connecting colloid.

[0005] Although the prior art provides a variety of carbon source materials that can improve denitrification efficiency, the variety of materials is wide and easily causes secondary pollution. Summary of the invention

[0006] The purpose of the present invention is to provide a carbon source material for microbial cultivation and a preparation method thereof to solve the problems of insufficient carbon source and weak denitrification in the existing sewage treatment process. The carbon source material of the present invention has a simple composition and can effectively improve the denitrification efficiency.

[0007] The above technical objectives of the present invention are achieved through the following technical solutions:

[0008] One aspect of the present invention provides a method for preparing a carbon source material for microbial cultivation, comprising the following steps:

[0009] After gelatin and oxalic acid are mixed, they are stirred evenly at room temperature, and then concentrated sulfuric acid with a concentration of 70-80wt% is added to the mixture for reaction, and the mixture is slowly added dropwise while being stirred during the addition process. After the addition is completed, the product is cooled to room temperature, and then the product is washed and dried to obtain a carbon source precursor material;

[0010] The obtained carbon source precursor material is immersed in an ethanol solution containing fluorinated silane overnight, then washed and sintered, the obtained product is ground into powder and then trace elements and vitamins are added and mixed evenly;

[0011] The mixed material is added into a twin-screw extruder, heated and melted, and then extruded. The extrusion end is blown at 5-15 L / L·min. The diameter of the extrusion die hole is 1-5 cm. The extrudate is cooled and cut into a length of 1-10 cm to obtain a slow-release carbon source filler.

[0012] Furthermore, the mass ratio of gelatin to oxalic acid is 1:1-3.

[0013] Furthermore, the concentrated sulfuric acid is added in a ratio of 2-3:1 to the mixture.

[0014] Furthermore, the concentration of the fluorinated silane ethanol solution is 4-8 mg / mL.

[0015] Furthermore, the sintering conditions are: nitrogen or hydrogen atmosphere, temperature of 200-400° C., time of 6-8 h.

[0016] Furthermore, the grinding conditions are: rotation speed 600-800 rpm, time 1-2h.

[0017] Furthermore, the trace elements include Ca 2+ ,Mg 2+ , Fe 3+ , Zn 2+ , Cu 2+ , K + .

[0018] Furthermore, the vitamins are vitamin D3, vitamin B1, vitamin B12 .

[0019] Furthermore, the head temperature of the twin-screw extruder is 110-120°C, the middle section temperature is set to 150-220°C, and the extrusion temperature is set to 140-170°C.

[0020] The beneficial effects brought by the present invention are as follows: the present invention uses gelatin as a raw material and can increase the surface structural characteristics of gelatin molecules by mixing with oxalic acid. On the one hand, oxalic acid is weaker than organic acid, and on the other hand, as an organic acid, it has little harm to the environment. The mixture is carbonized under the action of concentrated sulfuric acid, so that the raw materials can be fully utilized to avoid waste, and no impurities are generated. The product is washed and dried to obtain a carbon source precursor material, and the obtained material has high purity. Soaking the carbon source precursor material in an ethanol solution containing fluorine silane can increase the number of pores and pore area of ​​the carbon source precursor material, and at the same time can enhance the covalent binding ability of the carbon source precursor material, so that after mixing with vitamins and trace elements, the binding ability between them can be enhanced, so that the obtained material has higher stability. The final carbon source material is extruded into a block by an extruder, which can extend the practical time of the carbon source, ensure its stability, and avoid secondary pollution to the environment. The carbon source material of the present invention has a simple composition, does not contain chemical substances harmful to the environment, and has good environmental protection. The preparation method of the present invention is simple and suitable for industrial production. DETAILED DESCRIPTION

[0021] In order to make the technical means, creative features, objectives and effects of the present invention easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1

[0023] A carbon source material for microbial cultivation, the preparation method of which comprises the following steps:

[0024] 1 part of gelatin and 2 parts of oxalic acid are mixed and stirred at room temperature, and then 6 parts of concentrated sulfuric acid with a concentration of 70wt% are added to the mixture for reaction, and the mixture is slowly added dropwise while being stirred during the addition process. After the addition is completed, the product is cooled to room temperature, and then the product is washed and dried to obtain a carbon source precursor material;

[0025] The obtained carbon source precursor material was immersed in an ethanol solution of 6 mg / mL fluorinated silane overnight, then washed, sintered at 300 °C for 7 h in a hydrogen atmosphere, and the obtained product was ground into powder at 700 rpm for 2 h, and then trace elements (Ca 2+ ,Mg 2+ , Fe 3+ , Zn 2+ , Cu 2+ , K + ), vitamins (vitamin D3, vitamin B1, vitamin B 12 ) Mix well;

[0026] The above-mentioned mixed material is added into a twin-screw extruder, the head temperature of the twin-screw extruder is 120°C, the middle section temperature is set to 200°C, the extrusion temperature is set to 160°C, and it is extruded after being heated and melted. The air blowing at the extrusion end is 10L / L·min, and the extrusion die hole diameter is 1-5cm. After the extrudate is cooled, it is cut into a length of 1-10cm to obtain a slow-release carbon source filler.

[0027] Example 2

[0028] A carbon source material for microbial cultivation, the preparation method of which comprises the following steps:

[0029] 1 part of gelatin and 1 part of oxalic acid are mixed and stirred at room temperature, and then 6 parts of concentrated sulfuric acid with a concentration of 80wt% are added to the mixture for reaction, and the mixture is slowly added dropwise while being stirred during the addition process. After the addition is completed, the product is cooled to room temperature, and then the product is washed and dried to obtain a carbon source precursor material;

[0030] The obtained carbon source precursor material was immersed in an ethanol solution of 8 mg / mL fluorinated silane overnight, then washed, sintered at 200 °C for 7 h in a hydrogen atmosphere, and the obtained product was ground into powder at 700 rpm for 2 h, and then trace elements (Ca 2+ ,Mg 2+ , Fe 3+ , Zn 2+ , Cu 2+ , K + ), vitamins (vitamin D3, vitamin B1, vitamin B 12 ) Mix well;

[0031] The above-mentioned mixed material is added into a twin-screw extruder, the head temperature of the twin-screw extruder is 120°C, the middle section temperature is set to 200°C, the extrusion temperature is set to 160°C, and it is extruded after being heated and melted. The air blowing at the extrusion end is 10L / L·min, and the extrusion die hole diameter is 1-5cm. After the extrudate is cooled, it is cut into a length of 1-10cm to obtain a slow-release carbon source filler.

[0032] Example 3

[0033] A carbon source material for microbial cultivation, the preparation method of which comprises the following steps:

[0034] 1 part of gelatin and 3 parts of oxalic acid are mixed and stirred at room temperature, and then 8 parts of concentrated sulfuric acid with a concentration of 80wt% are added to the mixture for reaction, and the mixture is slowly added dropwise while being stirred during the addition process. After the addition is completed, the product is cooled to room temperature, and then the product is washed and dried to obtain a carbon source precursor material;

[0035] The obtained carbon source precursor material was immersed in an ethanol solution of 4 mg / mL fluorinated silane overnight, then washed, sintered at 200 °C for 7 h in a hydrogen atmosphere, and the obtained product was ground into powder at 700 rpm for 2 h, and then trace elements (Ca 2+ ,Mg 2+ , Fe 3+ , Zn 2+ , Cu 2+ , K + ), vitamins (vitamin D3, vitamin B1, vitamin B 12 ) Mix well;

[0036] The above-mentioned mixed material is added into a twin-screw extruder, the head temperature of the twin-screw extruder is 120°C, the middle section temperature is set to 200°C, the extrusion temperature is set to 160°C, and it is extruded after being heated and melted. The air blowing at the extrusion end is 10L / L·min, and the extrusion die hole diameter is 1-5cm. After the extrudate is cooled, it is cut into a length of 1-10cm to obtain a slow-release carbon source filler.

[0037] Example 4

[0038] A carbon source material for microbial cultivation, the preparation method of which comprises the following steps:

[0039] 1 part of gelatin and 1 part of oxalic acid are mixed and stirred at room temperature, and then 4 parts of concentrated sulfuric acid with a concentration of 75wt% are added to the mixture for reaction, and the mixture is slowly added dropwise while being stirred during the addition process. After the addition is completed, the product is cooled to room temperature, and then the product is washed and dried to obtain a carbon source precursor material;

[0040] The obtained carbon source precursor material was immersed in an ethanol solution of 6 mg / mL fluorinated silane overnight, then washed, sintered at 400 °C for 6 h in a hydrogen atmosphere, and the obtained product was ground into powder at 600 rpm for 1 h, and then trace elements (Ca 2+ ,Mg 2+ , Fe 3+ , Zn 2+ , Cu2+ , K + ), vitamins (vitamin D3, vitamin B1, vitamin B 12 ) Mix well;

[0041] The above-mentioned mixed material is added into a twin-screw extruder, the head temperature of the twin-screw extruder is 120°C, the middle section temperature is set to 200°C, the extrusion temperature is set to 160°C, and it is extruded after being heated and melted. The air blowing at the extrusion end is 10L / L·min, and the extrusion die hole diameter is 1-5cm. After the extrudate is cooled, it is cut into a length of 1-10cm to obtain a slow-release carbon source filler.

[0042] Example 5

[0043] A carbon source material for microbial cultivation, the preparation method of which comprises the following steps:

[0044] 1 part of gelatin and 2 parts of oxalic acid are mixed and stirred at room temperature, and then 6 parts of concentrated sulfuric acid with a concentration of 75wt% are added to the mixture for reaction, and the mixture is slowly added dropwise while being stirred during the addition process. After the addition is completed, the product is cooled to room temperature, and then the product is washed and dried to obtain a carbon source precursor material;

[0045] The obtained carbon source precursor material was immersed in an ethanol solution of 6 mg / mL fluorinated silane overnight, then washed, sintered at 400 °C for 8 h in a hydrogen atmosphere, and the obtained product was ground into powder at 800 rpm for 1 h, and then trace elements (Ca 2+ ,Mg 2+ , Fe 3+ , Zn 2+ , Cu 2+ , K + ), vitamins (vitamin D3, vitamin B1, vitamin B 12 ) Mix well;

[0046] The above-mentioned mixed material is added into a twin-screw extruder with a head temperature of 110°C, a middle section temperature of 150°C, and an extrusion temperature of 170°C. After heating and melting, the mixed material is extruded. The air blowing at the extrusion end is 10L / L·min. The diameter of the extrusion die hole is 1-5cm. After the extrudate is cooled, it is cut into a length of 1-10cm to obtain a slow-release carbon source filler.

[0047] Example 6

[0048] A carbon source material for microbial cultivation, the preparation method of which comprises the following steps:

[0049] 1 part of gelatin and 2 parts of oxalic acid are mixed and stirred at room temperature, and then 8 parts of concentrated sulfuric acid with a concentration of 75wt% are added to the mixture for reaction, and the mixture is slowly added dropwise while being stirred during the addition process. After the addition is completed, the product is cooled to room temperature, and then the product is washed and dried to obtain a carbon source precursor material;

[0050] The obtained carbon source precursor material was immersed in an ethanol solution of 8 mg / mL fluorinated silane overnight, then washed, sintered at 400 °C for 8 h in a hydrogen atmosphere, and the obtained product was ground into powder at 800 rpm for 2 h, and then trace elements (Ca 2+ ,Mg 2+ , Fe 3+ , Zn 2+ , Cu 2+ , K + ), vitamins (vitamin D3, vitamin B1, vitamin B 12 ) Mix well;

[0051] The above-mentioned mixed material is added into a twin-screw extruder with a head temperature of 110°C, a middle section temperature of 220°C, and an extrusion temperature of 140°C. After heating and melting, the mixed material is extruded. The air blowing at the extrusion end is 15L / L·min. The diameter of the extrusion die hole is 1-5cm. After the extrudate is cooled, it is cut into a length of 1-10cm to obtain a slow-release carbon source filler.

[0052] Comparative Example 1

[0053] A carbon source material for microbial cultivation, the preparation method of which comprises the following steps:

[0054] Add 6 parts of concentrated sulfuric acid with a concentration of 70 wt% to 1 part of gelatin for reaction, slowly dropwise add the mixture while stirring, and after the dropwise addition is completed, cool the product to room temperature, and then wash and dry the product to obtain a carbon source precursor material;

[0055] The obtained carbon source precursor material was immersed in an ethanol solution of 6 mg / mL fluorinated silane overnight, then washed, sintered at 300 °C for 7 h in a hydrogen atmosphere, and the obtained product was ground into powder at 700 rpm for 2 h, and then trace elements (Ca 2+ ,Mg 2+ , Fe 3+ , Zn 2+ , Cu 2+ , K + ), vitamins (vitamin D3, vitamin B1, vitamin B 12 ) Mix well;

[0056] The above-mentioned mixed material is added into a twin-screw extruder, the head temperature of the twin-screw extruder is 120°C, the middle section temperature is set to 200°C, the extrusion temperature is set to 160°C, and it is extruded after being heated and melted. The air blowing at the extrusion end is 10L / L·min, and the extrusion die hole diameter is 1-5cm. After the extrudate is cooled, it is cut into a length of 1-10cm to obtain a slow-release carbon source filler.

[0057] Application Example 1 Effect of Carbon Source Materials on Total Nitrogen Removal Rate

[0058] A water sample from the anaerobic section of a sewage plant was selected for denitrification test, with a sludge concentration of 2000-3000 mg / L, a total nitrogen of 59 mg / L, and a COD of 75 mg / L. 1000 mL of the water sample was stirred at the same speed in a stirrer, and the denitrification carbon sources of Examples 1-6 and Comparative Example 1 were added as external carbon sources, and their effects on the denitrification rate and total nitrogen removal rate were statistically analyzed. The results are shown in Table 1.

[0059] Table 1 Effect of denitrification carbon source on total nitrogen removal rate

[0060] Carbon source 4h total nitrogen removal rate (%) 8h total nitrogen removal rate (%) 16h total nitrogen removal rate (%) Example 1 76.35 91.29 99.37 Example 2 71.41 85.63 96.91 Example 3 69.93 81.79 97.82 Example 4 70.04 81.61 90.74 Example 5 71.39 82.78 90.56 Example 6 66.87 78.64 94.06 Comparative Example 1 27.93 49.38 66.84

[0061] It can be seen from the results in Table 1 that the denitrification carbon sources of Examples 1 to 6 of the present invention have a high denitrification total nitrogen removal rate and a small amount of use compared to the denitrification carbon source of Comparative Example 1. Compared with the simple carbon source, the denitrification total nitrogen removal efficiency and capacity have obvious technical advantages in both the short-term and long-term processes.

[0062] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes by using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a carbon source material for microbial cultivation, characterized in that: The following steps are involved: The gelatin and oxalic acid are mixed and stirred at room temperature, and then concentrated sulfuric acid with a concentration of 70-80wt% is added to the mixture for reaction, and the mixture is slowly added dropwise while being stirred during the addition process. After the addition is completed, the product is cooled to room temperature, and then the product is washed and dried to obtain a carbon source precursor material; The obtained carbon source precursor material is immersed in an ethanol solution containing fluorinated silane overnight, then washed and sintered, the obtained product is ground into powder and then trace elements and vitamins are added and mixed evenly; The mixed material is added into a twin-screw extruder, and extruded after being heated and melted, and air is blown at the extrusion end at 5-15 L / L·min, and the diameter of the extrusion die hole is 1-5 cm. The extruded material is cooled and cut into a length of 1-10 cm to obtain a slow-release carbon source filler; The mass ratio of gelatin to oxalic acid is 1:1-3.

2. The method for preparing a carbon source material for microbial cultivation according to claim 1, characterized in that: The concentrated sulfuric acid is added in a ratio of 2-3:1 to the mixture.

3. The method for preparing a carbon source material for microbial cultivation according to claim 1, characterized in that: The concentration of the fluorinated silane ethanol solution is 4-8 mg / mL.

4. The method for preparing a carbon source material for microbial cultivation according to claim 1, characterized in that: The sintering conditions are: nitrogen or hydrogen atmosphere, temperature of 200-400° C., and time of 6-8 hours.

5. The method for preparing a carbon source material for microbial cultivation according to claim 1, characterized in that: The grinding conditions are: rotation speed 600-800 rpm, time 1-2 h.

6. The method for preparing a carbon source material for microbial cultivation according to claim 1, characterized in that: The trace elements include Ca 2+ ,Mg 2+ , Fe 3+ , Zn 2+ , Cu 2+ , K + .

7. The method for preparing a carbon source material for microbial cultivation according to claim 1, characterized in that: The vitamins are microbial D3, vitamin B1, vitamin B 12 .