CN106747734B - Method for reducing nitrogen loss in composting process by utilizing nano silver - Google Patents

Abstract

The invention discloses a method for reducing nitrogen loss in the composting process by using a nano-silver solution, which comprises the following steps: adding the nano-silver solution to compost raw materials to obtain a compost; placing the compost on an outer layer wrapped with a thermal insulation film In the compost container, for indoor composting. The method of the invention can reduce the loss of nitrogen in the composting process with the advantages of high treatment efficiency, good treatment effect, simple treatment process and convenient operation.

Description

A method for reducing nitrogen loss during composting using nano-silver

technical field

The invention relates to a method for controlling nitrogen loss in the composting process, in particular to a preparation method of nanometer silver and its application in reducing nitrogen loss in the composting process.

Background technique

At present, composting technology has been widely used in the disposal of agricultural waste, sludge, manure, biological waste and other wastes. It can convert biodegradable components into pollution-free and hygienic humus substances, so that these wastes can be regenerated. Add to soil as fertilizer or amendment.

Sludge is an unavoidable by-product in sewage treatment plants. With the development of technology and sewage treatment plants, the output of sludge is also increasing. Since sludge is rich in nutrients, especially nitrogen and phosphorus, the finished product of sludge compost is widely used in agriculture. However, due to the high moisture content and low carbon-nitrogen ratio of sludge, nitrogen is easily lost in the form of ammonia during the composting process. Therefore, adding a certain amount of substances with higher carbon content to sludge compost can reduce nitrogen loss, such as straw and sawdust. At the same time, vegetable leaves are added to the compost as easily degradable substances, which is beneficial to the composting process. Bran can adjust the initial carbon-nitrogen ratio of compost.

The high specific surface area makes the nanoparticles very toxic. At present, nano-silver has received widespread attention in many fields, such as: personal care products, cosmetics, film materials, food containers, etc. Many studies have found that nano-silver has certain effects on nano-silver on nitrification, denitrification processes and related microorganisms. Studies have pointed out that in soil ecosystems, denitrification and denitrification microorganisms are more likely to be inhibited by nano-silver, and this effect is more serious as the concentration of nano-silver increases. It has also been found that the nitrification process and nitrifying microorganisms are more susceptible than denitrification and its associated microorganisms. Although the effect of nano-silver on nitrogen transfer and transformation has attracted the attention of many researchers, the application of nano-silver in the field of composting has not received much attention. At present, researchers have adopted many methods to reduce nitrogen loss in the composting process, increase the nitrogen content in the finished compost, such as adding biochar, zeolite, etc., or control the temperature, moisture content, pH, and ventilation conditions of the composting environment. Reduce nitrogen loss. These methods do not directly inhibit or promote the nitrogen cycling function of microorganisms, which is an activity performed by related microorganisms. Therefore, it is of great significance to add a certain amount of reagents that have a direct impact on nitrogen cycle microorganisms in the composting process to reduce nitrogen loss during composting.

Contents of the invention

The technical problem to be solved in the present invention is to overcome the deficiencies of the prior art, provide a kind of nano-silver with good stability, and also provide a kind of nano-silver preparation method with simple process and rapid production; on this basis, also provide a kind of The aforementioned application of nano-silver can reduce the loss of nitrogen in the composting process with the advantages of high treatment efficiency, good treatment effect, simple treatment process, and convenient operation.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A method utilizing nanometer silver solution to reduce nitrogen loss during composting, comprising the following steps:

S1, adding the nano-silver solution to the compost raw material to obtain a heap;

S2. The compost is placed in a compost container wrapped with a thermal insulation film to perform indoor composting.

In the above method, preferably, the nano-silver in the nano-silver solution is nano-silver particles wrapped with polyvinylpyrrolidone.

Above-mentioned method, preferably, the nano-silver particle of described polyvinylpyrrolidone wrapping adopts following method to prepare:

S1-1. Place the polyvinylpyrrolidone solution in an ice bath environment and perform magnetic stirring;

S1-2, adding NaBH ₄ to the polyvinylpyrrolidone solution to obtain a mixed solution;

S1-3. Add the AgNO ₃ solution dropwise into the mixed solution, and stir magnetically for 0.5-1 hour.

In the above method, preferably, the mass concentration of the polyvinylpyrrolidone solution is 1% to 1.5%, and the content of NaBH ₄ in the mixed solution is 2.0×10 ^-3 M to 2.5×10 ^-3 M; The concentration of the AgNO ₃ solution is 4.5×10 ^{-3 M˜5} ×10 ^-3 M.

The above-mentioned method, preferably, in the S1 step, the compost raw materials include rice straw, sludge, vegetable leaves and bran; the wet weight ratio of the rice straw, sludge, vegetable leaves and bran is 36: 22:5:5.

In the above method, preferably, the rice straw is air-dried rice straw with a length of 10 mm to 20 mm; the sludge is air-dried sludge that has been ground and passed through a 100-mesh sieve; the vegetables are air-dried rice straw with a length of 10 mm to 20 mm. Vegetables; the bran is air-dried bran.

In the above method, preferably, in the step S1, the concentration of nano-silver in the stack is 2-20 mg/(kgcompost).

In the above method, preferably, the lid of the compost container is provided with 5 through holes.

In the above method, preferably, the indoor composting process lasts for 60 days.

In the above method, preferably, in the indoor composting process, the compost is turned once a day for the first two weeks, and then turned once a week thereafter.

In the above method, preferably, the moisture content of the pile is 60%-65%; the carbon-nitrogen ratio is 25:1-30:1.

Compared with the prior art, the present invention has the advantages of:

(1) The present invention provides a kind of method that utilizes nano-silver solution to reduce nitrogen loss in composting process, adds nano-silver in compost, because the transfer conversion of nitrogen is exactly carried out by the activity of microorganism, so the nitrogen loss The change should be due to the activity, abundance, and diversity of related microorganisms being affected by nano-silver, thereby affecting nitrogen transfer and transformation. The present invention utilizes the antibacterial properties of nano-silver to inhibit the activity of related microorganisms that lead to the reduction of nitrogen, so that the transfer and conversion of nitrogen that leads to the reduction of nitrogen is also inhibited; at the same time, the activity of microorganisms that lead to the reduction of nitrogen loss is activated, thereby causing Nitrogen transfer and conversion activities with reduced nitrogen loss are also enhanced, thereby reducing the loss of nitrogen in the composting process. It has the advantages of high treatment efficiency, good treatment effect, simple treatment process, and convenient operation.

(2) the present invention provides a kind of method utilizing nano-silver solution to reduce nitrogen loss in the composting process, its nano-silver adopts polyvinylpyrrolidone wrapping, because composting environment has high price background electrolyte, high ionic strength; If simply adopt Nano silver is prone to agglomeration. The invention adopts the nano-silver wrapped by polyvinyl pyrrolidone, which can keep stable in the composting environment without agglomeration phenomenon.

Description of drawings

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention.

Fig. 1 is the detection of nano-silver in the embodiment 1 of the present invention; Wherein Fig. A is the ultraviolet absorption spectrogram, Fig. B is the particle size distribution diagram; Fig. C is the transmission electron microscope diagram; Fig. D is the energy spectrum analysis diagram.

Fig. 2 is the change trend diagram of the total nitrogen content over time in the composting process with nano-silver concentrations of 2 mg/kg, 10 mg/kg, and 20 mg/kg respectively in Example 2.

Fig. 3 is a graph showing the trend of total nitrogen loss over time during the composting process with nano-silver concentrations of 2 mg/kg, 10 mg/kg, and 20 mg/kg, respectively, in Example 2.

Fig. 4 is a graph showing the change trend of inorganic nitrogen over time in the composting process with nano-silver concentrations of 2 mg/kg, 10 mg/kg, and 20 mg/kg respectively in Example 2.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

Example

All materials and instruments used in the following examples are commercially available.

Example 1

A method utilizing nanometer silver solution to reduce nitrogen loss during composting, comprising the following steps:

(1) preparing nano-silver, comprising the following steps:

1.1 Prepare 300ml of polyvinylpyrrolidone solution with a mass concentration of 1%, place it in an ice bath environment and perform magnetic stirring.

1.2 Add NaBH ₄ to the polyvinylpyrrolidone solution to obtain a mixed solution, so that the concentration of NaBH ₄ in the mixed solution is 2.5×10 ^-3 M.

1.3 Add 100 ml of AgNO ₃ solution with a concentration of 5×10 ⁻³ M dropwise (~1 drop/second) into the mixed solution and perform magnetic stirring for 1 hour to obtain silver nanoparticles.

The prepared nano-silver was subjected to ultraviolet absorption spectrum measurement, dynamic particle size measurement, transmission electron microscope scanning and energy spectrum analysis, and the results are shown in Figure 1.

As can be seen from Figure 1A: an absorption peak has appeared near the wavelength of 400nm, indicating that the nano-silver particles coated with polyvinylpyrrolidone have been successfully synthesized; as can be seen from Figure 1B: the average particle diameter of nano-silver particles It is about 8.5nm; it can be seen from Figure 1C that the silver nanoparticles are uniformly distributed in a spherical shape, and the average particle size is about 6nm; it can be seen from Figure 1D that the black particles in Figure 1C are silver nanoparticles, which further proves that The present invention has successfully synthesized nano-silver.

Example 2

A method utilizing nanometer silver solution to reduce nitrogen loss during composting, comprising the following steps:

(1) Preparation of compost raw materials:

1.1 Prepare straw straw, sludge, vegetable leaves and bran respectively:

Rice straw: taken from the suburbs of Changsha City, Hunan Province, and cut into lengths of 10 to 20 mm after air-drying.

Sludge: It was taken from the sewage treatment plant in Yuelu District, Changsha City, Southern Province, air-dried, and ground through a 100-mesh sieve.

Vegetable leaves: taken from the vegetable market near Hunan University in Changsha City, Hunan Province, air-dried, and cut into lengths of 10 to 20 mm.

Bran: air dry.

The physical and chemical parameters of the aforementioned compost raw materials were measured, and the results are shown in Table 1.

Table 1: Physicochemical parameters of compost raw materials

raw material Moisture content (%)) Total organic carbon (g/kg) Total nitrogen (g/kg) carbon to nitrogen ratio pH sludge 9.48 178.9 24.2 7.4 6.74 straw straw 10.35 488.9 10.3 47.5 -^a vegetable 94.84 446.4 19.6 22.8 -^a bran 14.62 528.2 25.1 21.0 -^a

^a Parameters not measured

1.2. Compost raw materials are obtained by mixing rice straw, sludge, vegetable leaves and bran in a mass ratio of 36:22:5:5.

(2) Get the nano silver of embodiment 1, be mixed with nano silver solution.

(3) The compost raw material of step (1) is divided into three parts on average, is placed in 3 different compost containers (compost container outer layer is wrapped with plastic wrap), adds nano-silver solution respectively to make the concentration of nano-silver in the heap body be 2mg/kg, 10mg/kg, 20mg/kg, make the mixture uniform, and set a blank control group at the same time.

(4) Leave 5 small holes on the lid of the compost container so that the outside air can enter; Turn over once a day for the first two weeks, then once a week thereafter. The composting process lasts 60 days.

Investigate the total nitrogen content, total nitrogen loss and inorganic nitrogen content of the compost with nano-silver concentration of 2mg/kg, 10mg/kg, 20mg/kg within 60 days of composting.

Fig. 2 is a blank control group (blank group does not add nano-silver solution), and nano-silver concentration is respectively 2mg/kg, 10mg/kg, 20mg/kg total nitrogen content in the composting process trend chart. It can be seen from Figure 2 that the total nitrogen content in the heap with the nano-silver concentration of 10mg/kg is the highest.

Fig. 3 is a graph showing the change trend of total nitrogen loss over time in the composting process of the blank control group and nano-silver concentrations of 2 mg/kg, 10 mg/kg, and 20 mg/kg respectively. It can be seen from Figure 3 that at the end of composting, the nitrogen loss in the heap with a nano-silver concentration of 10 mg/kg is the least, indicating that the effect of reducing the nitrogen loss during the composting process is the best when the nano-silver concentration is 10 mg/kg.

Fig. 4 is a graph showing the change trend of inorganic nitrogen over time in the composting process of the blank control group and the nano-silver concentrations of 2 mg/kg, 10 mg/kg, and 20 mg/kg respectively. It can be seen from Figure 4 that at the end of composting, the inorganic nitrogen content in the heap with a nano-silver concentration of 10 mg/kg is the highest, indicating that when the nano-silver concentration is 10 mg/kg, the fertilizer efficiency of the compost product is the highest.

As can be seen from the above, the use of nano-silver of the present invention to reduce the treatment efficiency of nitrogen loss in the composting process is high. When the concentration of nano-silver is 10mg/kg, the effect of reducing nitrogen loss is the best, and the compost product can be improved to the greatest extent simultaneously. fertilizer effect.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with the art, without departing from the spirit and technical solutions of the present invention, can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solutions of the present invention, or modify them to be equivalent Variations of equivalent embodiments. Therefore, any simple modifications, equivalent replacements, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solutions of the present invention, still fall within the protection scope of the technical solutions of the present invention.

Claims (4)

1. A method for reducing nitrogen loss in a composting process by using a nano-silver solution is characterized by comprising the following steps:

S1, adding the nano-silver solution into the compost raw material to obtain a compost body; the nano silver in the nano silver solution is nano silver particles coated with polyvinylpyrrolidone; the concentration of the nano silver in the stack body is 10 mg/kg; the compost raw materials comprise straw stalks, sludge, vegetable leaves and bran; the mass ratio of the straw stalks, the sludge, the vegetable leaves and the bran is 36: 22: 5;

S2, placing the compost body in a compost container with an outer layer wrapped with a heat preservation film for indoor composting; the cover of the compost container is provided with 5 through holes; the indoor composting process lasts 60 days; turning the piles once every day in the first two weeks and then turning the piles once every week; the water content of the pile body is 60-65%; the carbon-nitrogen ratio is 25: 1-30: 1.

2. The method of claim 1, wherein the polyvinylpyrrolidone-coated nanosilver particles are prepared using the following method:

S1-1, placing the polyvinylpyrrolidone solution in an ice bath environment and carrying out magnetic stirring;

S1-2, adding NaBH4 into the polyvinylpyrrolidone solution to obtain a mixed solution;

S1-3, dropwise adding the AgNO3 solution into the mixed solution, and magnetically stirring for 0.5-1 h.

3. The method according to claim 2, wherein the mass concentration of the polyvinylpyrrolidone solution is 1% to 1.5%, and the content of NaBH4 in the mixed solution is 2.0 x 10 "3M to 2.5 x 10" 3M; the concentration of the AgNO3 solution is 4.5X 10-3M-5X 10-3M.

4. The method of claim 1, wherein the rice straw is air-dried rice straw 10mm to 20mm long; the sludge is obtained by grinding air-dried sludge and sieving the ground sludge with a 100-mesh sieve; the vegetables are air-dried vegetables with the length of 10 mm-20 mm; the bran is air-dried bran.