CN114455997A - A method for preparing biochar base fertilizer based on hydrothermal carbonization - Google Patents

Abstract

The invention belongs to the technical field of biochar base fertilizer preparation, and discloses a method for preparing biochar base fertilizer based on a hydrothermal carbonization method. The solvent is mixed, and hydrothermally acidified; the product of the hydrothermal acidification is pumped into the hydrothermal reaction kettle, and hydrothermally carbonized at 180 to 250 ° C for 90 to 240 minutes, and the reaction product is cooled, dehydrated, and dried to form biochar base; mixing the biochar base with inorganic fertilizer, calcium oxide, binder, and water, and extruding the mixture to obtain biochar-based granular fertilizer; The organic solid phase material obtained after the phase separation of the kitchen waste is used as the raw material for the hydrothermal carbonization reaction, and is also pretreated by hot water acidification. Based on this, the shortcomings of impure products, high oil and high salt after the reaction are effectively solved, and the quality of biomass charcoal.

Description

A method for preparing biochar base fertilizer based on hydrothermal carbonization

technical field

The invention belongs to the technical field of biochar base fertilizer preparation, and in particular relates to a method for preparing biochar base fertilizer based on a hydrothermal carbonization method.

Background technique

In recent years, the application of hydrothermal carbonization to treat food waste has received special attention. Compared with other thermochemical (pyrolysis, liquefaction) and biotransformation (fermentation, composting) technologies, hydrothermal carbonization has the advantages of no drying of raw materials, low energy consumption, and equipment. It has the advantages of small size, high carbon fixation efficiency, and easy storage and transportation of products. It has significant advantages in treating organic wastes with high moisture content and dispersion.

Hydrothermal carbonization means that in a closed system, using carbohydrates or lignocellulose as raw materials and water as the reaction medium, under a certain temperature (180-250 ° C) and self-generated pressure, the raw materials undergo a series of complex processes. The process of converting into carbon materials by reaction, the formed biomass carbon materials have the characteristics of developed pore structure, high specific surface area, stable aromatic structure and abundant surface functional groups, etc., with strong adsorption capacity, stable chemical properties and regeneration. The advantages of strong ability and so on.

At present, the mainstream process route of kitchen waste treatment at home and abroad mainly includes three stages: "pretreatment, resource treatment and product resource utilization". The organic solid phase material formed by the pretreatment of food waste through sorting, sand removal, crushing, pulping and oil-water-solid three-phase separation, usually using wet/dry anaerobic nitrification, fertilizer or protein feed Other resource-based treatment processes are used to further utilize product resources. Among them, the fertilizer technology is due to incomplete sterilization, high fertilizer salt content, unbalanced nutrient distribution ratio, long compost treatment cycle, large area and relatively poor sanitation conditions. It is an inevitable trend in the future to develop new technology to improve fertilizer quality.

It has been reported that the biomass carbon products after hydrothermal carbonization of kitchen waste can be extended to various fields such as fuel energy, ecological environment protection, electrode capacitors and carbon composite materials (Wang Nan, 2016, Environmental Science and Technology, Vol. 39, S2 Expect). Biochar-based fertilizer is known as a new type of green and environmentally friendly fertilizer. At present, the combination of biomass charcoal and fertilizer has become a new development direction of biochar-based fertilizer. There are still no relevant reports on the research on raw materials of carbon-based fertilizers. In addition, if the kitchen waste is directly hydrothermally carbonized without pretreatment, it will cause problems such as complex product composition, high oil and high salt, and low carbon yield. After compounding with fertilizer, it is not conducive to improving the quality of fertilizer, and as a fertilizer Applied to the field, it still lacks various nutrients needed by crops.

SUMMARY OF THE INVENTION

In view of this, in order to solve the problems raised in the above background technology, the purpose of the present invention is to provide a method for preparing biochar-based fertilizer based on a hydrothermal carbonization method.

To achieve the above object, the present invention provides the following technical solutions:

A method for preparing biochar base fertilizer based on a hydrothermal carbonization method, comprising:

Three-phase separation of kitchen waste to obtain organic solid materials;

Mixing the organic solid phase material with an acidic solvent, and performing hydrothermal acidification treatment;

The product of the hydrothermal acidification treatment is pumped into a hydrothermal reaction kettle, and hydrothermally carbonized at 180-250° C. for 90-240 min, and the reaction product is cooled, dehydrated and dried to form a biochar base;

The biochar base is mixed with inorganic fertilizer, calcium oxide, binder and water, and the mixture is extruded and granulated to obtain biochar based granular fertilizer.

Preferably, the three-phase separation is oil-water-solid three-phase separation.

Preferably, the pH value of the acidic solvent is 2-3, and the acidic solvent includes water and HCL solution with a concentration of 0.01 mol/L.

Preferably, the water content of the organic solid phase material after mixing with the acidic solvent is 70-85%.

Preferably, in the hydrothermal acidification treatment: the treatment temperature is 20-30° C., and the treatment time is 10-20 min.

Preferably, when the biochar base is mixed with inorganic fertilizer, calcium oxide, binder, and water, it includes:

Mix and stir the biochar, inorganic fertilizer and calcium oxide at 200-300 Rad/min, pulverize after stirring for 40 minutes, and sieve with a 16-mesh screen;

Add binder and water to the powder obtained by sieving and mix well.

Preferably, the mixing percentage of the biochar, inorganic fertilizer and calcium oxide is 55-65%: 20-40%: 5-8%; the binder accounts for 2-5% of the total amount of the mixture, and the Water accounts for 5 to 10% of the total mixture.

Preferably, the inorganic fertilizer includes 12-20% urea, 6-10% superphosphate and 5-10% potassium sulfate.

Preferably, the nitrogen content in the urea is 46%; the phosphorus pentoxide content in the superphosphate is 18%; the potassium content in the potassium sulfate is 50%.

Preferably, the binder is modified starch.

Compared with the prior art, the present invention has the following beneficial effects:

In the method provided by the present invention, the organic solid phase material obtained after the three-phase separation of kitchen waste is used as the raw material for the hydrothermal carbonization reaction, and the hot water acidification pretreatment is also performed. The shortcomings of pure, high oil and high salt, thus effectively improving the quality of biomass carbon. In addition, the use of biochar compound inorganic fertilizer fertilizer technology can realize the precise ratio of each component of biochar base fertilizer, and effectively improve the quality of fertilizer.

Detailed ways

The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

A method for preparing biochar base fertilizer based on a hydrothermal carbonization method, comprising:

Three-phase separation of kitchen waste to obtain organic solid-phase materials; the three-phase separation includes operations such as buffering, draining, sorting, pulping, sand removal, and oil extraction to achieve oil-water-solid three-phase separation;

The organic solid phase material is pumped into the hydrothermal pre-reactor, and an acidic solvent including water and HCL solution is added, wherein the pH value of the acidic solvent is 2, the concentration of the HCL solution is 0.01 mol/L, and the organic solid phase material is combined with the HCL solution. The water content after mixing the acidic solvent is 85%, and the hydrothermal acidification treatment is performed at 25 °C for 10 minutes;

The product of hydrothermal acidification treatment is pumped into the hydrothermal reaction kettle, and hydrothermally carbonized at 250°C for 120 minutes, and the reaction product is cooled, dehydrated and dried to form a biochar base;

60% biochar based, 20% urea (46% nitrogen), 10% superphosphate (18% phosphorus pentoxide), 5% potassium sulfate (50% potassium) and 5 % calcium oxide was mixed and stirred for 40min at a speed of 250Rad/min, then pulverized and sieved with a 16-mesh sieve;

Add 2% binder (modified starch) and 10% water to the powder obtained by sieving, and mix well;

The mixture is extruded and granulated to obtain biochar-based granular fertilizer.

As mentioned above, the biochar base prepared in this example has a carbon production rate of 41.4%, a specific surface area of 5.01 m/g, an average adsorption pore size of 4.88 nm, and wherein the humic substance content is 38%, and the organic matter content is 62%. , the salt content is 0.22%, and the total nutrients including nitrogen, phosphorus and potassium are 4.9%;

In addition, the total nutrient content of nitrogen, phosphorus and potassium in the biochar-based granular fertilizer prepared in this example exceeds 25%, and the biochar content is 55%.

Example 2

A method for preparing biochar base fertilizer based on a hydrothermal carbonization method, comprising:

Three-phase separation of kitchen waste to obtain organic solid-phase materials; the three-phase separation includes operations such as buffering, draining, sorting, pulping, sand removal, and oil extraction to achieve oil-water-solid three-phase separation;

The organic solid phase material is pumped into the hydrothermal pre-reactor, and an acidic solvent including water and HCL solution is added, wherein the pH value of the acidic solvent is 3, the concentration of the HCL solution is 0.01 mol/L, and the organic solid phase material is combined with the HCL solution. The water content after mixing with the acidic solvent is 80%, and the hydrothermal acidification treatment is carried out at 25°C for 20min;

The product of hydrothermal acidification is pumped into a hydrothermal reaction kettle, and hydrothermally carbonized at 220°C for 180 minutes, and the reaction product is cooled, dehydrated and dried to form a biochar base;

65% biochar based, 12% urea (46% nitrogen), 10% superphosphate (18% phosphorus pentoxide), 5% potassium sulfate (50% potassium) and 8 % calcium oxide was mixed and stirred for 40min at a speed of 200Rad/min, then pulverized and sieved with a 16-mesh sieve;

Add 2% binder (modified starch) and 10% water to the powder obtained by sieving, and mix well;

The mixture is extruded and granulated to obtain biochar-based granular fertilizer.

As mentioned above, the biochar base prepared in this example has a carbon production rate of 52.7%, a specific surface area of 8.45m/g, an average adsorption pore size of 6.23nm, and wherein the humic substance content is 40%, and the organic matter content is 72% , the salt content is 0.22%, and the total nutrients including nitrogen, phosphorus and potassium are 6.7%;

In addition, the total nutrient content of nitrogen, phosphorus and potassium in the biochar-based granular fertilizer prepared in this example exceeds 25%, and the biochar content is 65%.

Example 3

A method for preparing biochar base fertilizer based on a hydrothermal carbonization method, comprising:

Three-phase separation of kitchen waste to obtain organic solid-phase materials; the three-phase separation includes operations such as buffering, draining, sorting, pulping, sand removal, and oil extraction to achieve oil-water-solid three-phase separation;

The organic solid phase material is pumped into the hydrothermal pre-reactor, and an acidic solvent including water and HCL solution is added, wherein the pH value of the acidic solvent is 3, the concentration of the HCL solution is 0.01 mol/L, and the organic solid phase material is combined with the HCL solution. The water content after mixing with the acidic solvent is 80%, and the hydrothermal acidification treatment is carried out at 30°C for 20min;

The product of hydrothermal acidification treatment was pumped into the hydrothermal reaction kettle, and hydrothermally carbonized at 180 °C for 240 min, and the reaction product was cooled, dehydrated and dried to form a biochar base;

55% biochar based, 20% urea (46% nitrogen), 10% superphosphate (18% phosphorus pentoxide), 10% potassium sulfate (50% potassium) and 8 % calcium oxide was mixed and stirred for 40min at a speed of 300Rad/min, then pulverized and sieved with a 16-mesh sieve;

Add 4% binder (modified starch) and 6% water to the powder obtained by sieving, and mix well;

The mixture is extruded and granulated to obtain biochar-based granular fertilizer.

As mentioned above, the biochar base prepared in this example has a carbon production rate of 49.8%, a specific surface area of 6.34m/g, an average adsorption pore size of 5.28nm, and wherein the humic substance content is 39%, and the organic matter content is 70%. , the salt content is 0.22%, and the total nutrients including nitrogen, phosphorus and potassium are 5.8%;

In addition, in the biochar-based granular fertilizer prepared in this embodiment, the total nutrient content of nitrogen, phosphorus and potassium is more than 25%, and the biochar content is 60%.

In summary, when the organic solid phase material obtained after the three-phase separation of kitchen waste is used as the raw material for the hydrothermal carbonization reaction, the carbon generation rate in the biochar base is 41.4-52.7%, and the specific surface area is 5.01-8.45 m/g, the average adsorption pore size is 4.88~6.23nm, the humus content is 38~40%, the organic matter content is 62~72%, the salt content is 0.22%, and the total nutrients including nitrogen, phosphorus and potassium are 4.9~6.7%; The biochar-based granular fertilizer prepared in this example includes a total nutrient content of nitrogen, phosphorus and potassium exceeding 25%, and a biochar content of 55-65%, which can effectively meet the national standard for biochar-based fertilizers.

Comparative Example 1

The untreated kitchen waste is pumped into the hydrothermal reaction kettle, and hydrothermally carbonized at 180～250℃ for 90～240min, and the reaction product is cooled, dehydrated and dried to form a biochar base.

In this comparative example, the carbon generation rate in the biochar base is 31.3-42.8%, the specific surface area is 3.21-5.65 m/g, and the average adsorption pore size is 2.57-4.43 nm.

From the above, based on the comparison between the above example and Comparative Example 1, it can be seen that the method of the present invention effectively improves the production quality of biochar-based.

Comparative Example 2

Three-phase separation of kitchen waste to obtain organic solid materials;

Composting processes organic solid-phase materials to obtain biochar bases.

In this comparative example, the humus content in the biochar base is 45.6%, the organic matter content is 39-43%, the salt content is 1.38%, and the total nutrients including nitrogen, phosphorus and potassium are 1.9-5.4%.

From the above, based on the comparison of the above-mentioned embodiment and Comparative Example 2, it can be known that humic substances and salt content are greatly reduced, thus effectively solving the problems such as impure products, high oil and high salt after the reaction; and organic matter contains and includes nitrogen, phosphorus and potassium. The content of total nutrients is greatly increased, thereby effectively increasing the nutrient content of the fertilizer prepared by the present invention, thereby improving the quality of the fertilizer.

In the above description, although the steps are described as a sequential process, many of the steps may be implemented alternatively, in parallel, concurrently, or simultaneously. Furthermore, the order of the steps can be rearranged. Also, the process may be terminated when its operation is complete, but may also have additional steps not included.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, and substitutions can be made in these embodiments without departing from the principle and spirit of the invention and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims (10)

1. A method for preparing a biochar-based fertilizer based on a hydrothermal carbonization method is characterized by comprising the following steps:

separating the kitchen waste by three phases to obtain an organic solid phase material;

mixing the organic solid phase material with an acidic solvent, and carrying out hydrothermal acidification treatment;

pumping the product of the hydrothermal acidification treatment into a hydrothermal reaction kettle, carrying out hydrothermal carbonization at 180-250 ℃ for 90-240 min, and cooling, dehydrating and drying the reaction product to form a biochar base;

and mixing the biochar base with an inorganic fertilizer, calcium oxide, a binder and water, and extruding and granulating the mixture to obtain the biochar-based granular fertilizer.

2. The method for preparing the biochar-based fertilizer based on the hydrothermal carbonization method as claimed in claim 1, is characterized in that: the three-phase separation is oil-water-solid three-phase separation.

3. The method for preparing the biochar-based fertilizer based on the hydrothermal carbonization method as claimed in claim 1, is characterized in that: the pH value of the acidic solvent is 2-3, and the acidic solvent comprises water and a HCL solution with the concentration of 0.01 mol/L.

4. The method for preparing the biochar-based fertilizer based on the hydrothermal carbonization method as claimed in claim 3, is characterized in that: the water content of the organic solid-phase material after being mixed with the acidic solvent is 70-85%.

5. The method for preparing the biochar-based fertilizer based on the hydrothermal carbonization method as claimed in claim 1, 3 or 4, wherein in the hydrothermal acidification treatment: the treatment temperature is 20-30 ℃, and the treatment time is 10-20 min.

6. The method for preparing the biochar-based fertilizer based on the hydrothermal carbonization method as claimed in claim 1, wherein the mixing of the biochar-based fertilizer with the inorganic fertilizer, calcium oxide, the binder and water comprises:

mixing and stirring the biochar base, the inorganic fertilizer and the calcium oxide at 200-300 Rad/min, stirring for 40min, crushing and sieving by using a 16-mesh sieve;

and adding a binder and water into the powder obtained by sieving, and uniformly mixing.

7. The method for preparing the biochar-based fertilizer based on the hydrothermal carbonization method as claimed in claim 1 or 6, wherein: the mixing percentage of the biochar base, the inorganic fertilizer and the calcium oxide is 55-65%: 20-40%: 5-8%; the binder accounts for 2-5% of the total amount of the mixture, and the water accounts for 5-10% of the total amount of the mixture.

8. The method for preparing the biochar-based fertilizer based on the hydrothermal carbonization method as claimed in claim 7, is characterized in that: the inorganic fertilizer comprises 12-20% of urea, 6-10% of calcium superphosphate and 5-10% of potassium sulfate.

9. The method for preparing the biochar-based fertilizer based on the hydrothermal carbonization method as claimed in claim 7, is characterized in that: the nitrogen content in the urea is 46 percent; the content of phosphorus pentoxide in the calcium superphosphate is 18 percent; the potassium content in the potassium sulfate is 50%.

10. The method for preparing the biochar-based fertilizer based on the hydrothermal carbonization method as claimed in claim 1, is characterized in that: the binder is modified starch.