CN106588274A - Method for preparing biomass charcoal-based slow-release organic fertilizer through agricultural solid waste - Google Patents

Abstract

The invention discloses a method for preparing biomass charcoal-based slow-release organic fertilizer from agricultural solid waste. The method is to prepare biochar with high adsorption capacity by pyrolyzing the agricultural solid waste at high temperature, and then absorb the treated biochar. For rural organic wastewater, the final preparation of biomass charcoal-based slow-release organic fertilizer includes the following steps: 1) Biochar preparation, 2) Biochar modification, 3) Rural organic wastewater pretreatment, 4) Biochar enrichment Nutrients, 5) Granulation. After the rural organic sewage is treated to a certain extent, macromolecules and particulate matter are removed, and then adsorbed by biochar to absorb a large amount of organic matter and nitrogen and phosphorus substances in the water body to the pores and surface area of the biochar, and then through the granulation method, The biochar-based slow-release organic fertilizer is prepared, and finally the slow-release fertilizer is added to the soil to improve soil properties, and the grown crops can provide raw materials for preparing biochar.

Description

A method for preparing biomass charcoal-based slow-release organic fertilizer from agricultural solid waste

technical field

The invention relates to the technical field of environmental protection, in particular to a method for preparing biomass charcoal-based slow-release organic fertilizer from agricultural solid waste.

Background technique

With the rapid development of the national economy and the acceleration of the industrialization process, the country has stepped up the control of urban and industrial pollution, but the problem of environmental pollution in the vast rural areas with relatively backward productivity and production methods has become increasingly prominent. There are still about 300 million rural areas in the country. People cannot drink clean water, and 150 million mu of arable land has been polluted. The water environment of rural rivers is seriously polluted, and its pollution is mainly caused by the joint pollution of farming wastewater, agricultural by-product processing (such as sweet potato starch production) wastewater, domestic sewage and other rural organic sewage, as well as solid waste such as agricultural straw, domestic garbage, and livestock manure. According to statistics, in 2015, rural areas produced about 8 billion tons of domestic sewage and 1.2 billion tons of solid waste. In addition, due to intensive agricultural farming (excessive use of chemical fertilizers and pesticides), soil acidification and land compaction have been exacerbated. Zhang Weili, a researcher at the Chinese Academy of Agricultural Sciences, pointed out that the amount of pesticides used in my country has reached 1.3 million tons, which is 2.5 times the world average level. Another On the one hand, about 450,000 tons of plastic film remains in the soil every year, leading to serious problems of soil quality degradation and pollution in my country's farmland, directly affecting food production and agricultural product safety.

On the other hand, agricultural production inevitably brings about straw problems. It is estimated that the national agricultural straw production is about 840 million tons per year. Crop straw is a renewable resource, but the current utilization rate of crop straw is low, and a large number of crops are abandoned or burned on the spot, which not only occupies a large amount of land, causes waste of resources, but also destroys the atmospheric environment. Black and harmful gases are also harmful to human health, especially to the respiratory tract. Domestic garbage, livestock and poultry manure and other solid waste also pollute the rural environment to varying degrees. In recent years, there have been more and more researches on the resource utilization of agricultural solid wastes, one of which is the preparation of biochar from agricultural solid wastes. Biochar is a porous solid substance formed by biomass under anaerobic or anoxic conditions. Biochar has excellent physical and chemical properties, which can adjust soil pH and base saturation, enhance soil water retention, effectively fix fertilizer nutrients, and effectively Adsorb anions and cations, pesticides and heavy metals in the soil, increase soil porosity and air permeability, reduce soil bulk density and other advantages, so it can be used as a soil improver, and it is also a high-quality slow-release material. Its porous nature determines Biochar has strong adsorption capacity and slow release capacity, which can adsorb a large amount of pollutants in the soil environment and reduce the risk of pollutants entering plants.

Although aquaculture wastewater, agricultural and sideline processing (such as sweet potato starch production) wastewater, domestic sewage and other rural sewage do not contain toxic and harmful pollutants, mostly nitrogen, phosphorus and other nutrients, but discharged into the environmental water will cause eutrophication of the water environment, And direct discharge into the farmland will cause the burning and excessive growth of crops. Therefore, based on the high adsorption capacity and good slow-release effect of biochar, the present invention uses agricultural solid waste such as agricultural straw, domestic garbage, and livestock and poultry manure as raw materials to produce biochar, and then modifies the biochar Sexual treatment improves the adsorption capacity, and then treats rural sewage such as aquaculture wastewater, agricultural and sideline processing (such as sweet potato starch production) wastewater, and domestic sewage that have been pretreated to a certain extent by adsorption and filtration to enrich and remove carbon, nitrogen, and phosphorus in sewage. and other nutrients to prepare biomass charcoal-based slow-release organic fertilizer, which is finally reused on the farmland. The invention can solve the pollution problems of rural sewage and solid waste at the same time, and can also effectively reduce the use of chemical fertilizers, restore and improve the quality of farmland soil, has a good prospect for industrial application, and is expected to achieve great economic and social benefits and environmental benefits.

Contents of the invention

The technical problem solved by the invention is that the agricultural solid waste and rural sewage cannot be well treated and recycled, causing certain environmental pollution.

In order to solve the above-mentioned technical problems, the technical solution of the present invention is: a method for preparing biomass charcoal-based slow-release organic fertilizers from agricultural solid wastes, which is to prepare high-capacity bio-fertilizers by pyrolyzing agricultural solid wastes Material charcoal, then adsorb the treated rural organic wastewater, and finally prepare biomass charcoal-based slow-release organic fertilizer, which specifically includes the following steps:

1) Preparation of biochar: crush agricultural solid waste to 0.5-10cm, put it in a tube furnace, pyrolyze and carbonize it at a temperature of 300-800℃, and process it for 8-10h to make biomass Charcoal, pyrolysis protection gas is nitrogen;

2) Biomass charcoal modification: modify the biochar obtained in step 1), the treatment method is: treat the biochar with water steam for 10-30min, and then mix with the modifier according to the ratio of 1:1-5 The volume ratio is mixed and added to the reactor. The modifier is a mixture solution containing 1-3wt% acrylic acid, 0.2-0.5wt% alkylsulfonate, and 0.1-1wt% TAED; mixing and stirring, time control In 10-20 minutes, the heating rate is 8-10°C/min until the temperature reaches the range of 60-80°C, and the constant temperature is maintained for 1-3.5 hours; then continue to heat up, and the heating rate is controlled at 5-10°C/min until the temperature Reach the range of 90-100°C, and keep the temperature at a constant temperature for 1.2-4.6 hours before discharging; then wash repeatedly with water until the pH value is 6-7.5; after drying, the temperature is controlled in the range of 130-140°C, and the water content is controlled at 1-2% to obtain modified biochar, which can increase the adsorption capacity of biochar to rural organic wastewater after modification;

3) Rural organic wastewater pretreatment: pretreat rural organic wastewater by hydrolytic acidification, UASB reactor, IC reactor, SBR, AAO, ultrasonic treatment and other wastewater treatment methods; hydrolytic acidification treatment can reduce the suspended solids of wastewater and improve the reliability Biochemical, UASB reactor, IC reactor, SBR, AAO, ultrasonic treatment and other wastewater treatment methods can further reduce suspended solids and macromolecular substances in water;

4) Enrichment of nutrients by biochar: Add the modified biochar obtained in step 2) to the rural organic wastewater pretreated in step 3), and the modified biochar will adsorb the wastewater. The method can be fixed bed, fluidized bed and other methods, and the flow rate of rural organic wastewater passing through the fixed bed or fluidized bed is controlled at 0.5-8BV/h, while preventing the biochar from flowing out with the water flow;

5) Granulation: add a binder to the adsorbed modified biochar in a weight ratio of 1:(0.1-10) to prepare a granular shape with uniform particle size, and obtain a biochar-based slow-release organic fertilizer .

After the rural organic sewage is treated to a certain extent, macromolecules and particulate matter are removed, and then adsorbed by biochar to absorb a large amount of organic matter and nitrogen and phosphorus substances in the water body to the pores and surface area of the biochar, and then through the granulation method, The biochar-based slow-release organic fertilizer is prepared, and finally the slow-release fertilizer is added to the soil to improve soil properties, and the grown crops can provide raw materials for preparing biochar.

Further, in the above scheme, the agricultural solid waste is selected from one or more of straw (corn, rice, wheat and other crops), grass, domestic garbage, and livestock dung.

Furthermore, the moisture content of the agricultural solid waste is 1 wt%.

Further, in the above scheme, the rural organic sewage is non-toxic and harmless high-concentration organic wastewater, selected from one or more of agricultural and sideline product processing wastewater, septic tank effluent, breeding wastewater, and wastewater related to family life. Several kinds.

Further, in the above solution, the way of enriching nutrients by the biochar can be one or more of fixed bed, fluidized bed, trickling filter bed and the like.

Further, in the above solution, the binder can be one or more of starch, clay, zeolite, bentonite, kaolin and the like.

Further, in the above scheme, the granulation method can be rolling granulation, stirring granulation, compression granulation, extrusion granulation, dry granulation, fluidized bed granulation, sintering and roasting, etc. One or several.

The beneficial effects of the present invention are:

1) The raw materials of biochar are all from rural organic solid waste, which has a wide range of sources and low cost;

2) The use of biochar to treat rural sewage not only effectively adsorbs nutrients such as nitrogen and phosphorus in rural sewage, but also plays a role in purifying rural sewage, and the treatment cost is low;

3) Rural sewage does not contain toxic and harmful substances, so it can be adsorbed with biochar and returned to the field;

4) Applying the biochar-based slow-release fertilizer to the field can effectively improve soil properties and increase soil carbon inventory;

5) The biomass charcoal-based slow-release fertilizer has a high fertilizer efficiency density, a long slow-release time, maintains soil fertility for a long time, improves the utilization efficiency of nutrient elements, and effectively solves the problem of soil burning seedlings caused by direct return of high-concentration rural sewage to the field;

6) Reduce agricultural non-point source pollution. The invention can be used for treating organic wastewater in rural areas, especially in areas where a complete biochemical system cannot be established to treat wastewater, and can reduce agricultural non-point source pollution to a large extent.

detailed description

Below in conjunction with specific embodiment, carry out further detailed description along with the present invention:

Example 1

Taking straw as agricultural solid waste, its water content is 1wt%, and using agricultural and sideline product processing wastewater as rural organic sewage to prepare biomass charcoal-based slow-release organic fertilizer. The specific method is as follows:

Biochar with high adsorption capacity is prepared by pyrolyzing agricultural solid waste at high temperature, then adsorbing treated rural organic wastewater, and finally preparing biochar-based slow-release organic fertilizer, which specifically includes the following steps:

1) Preparation of biochar: crush agricultural solid waste to 0.5cm, put it in a tube furnace, pyrolyze and carbonize it at a temperature of 300°C, and process it for 8 hours to make biochar. The gas is nitrogen;

2) Biomass charcoal modification: modify the biochar obtained in step 1), the treatment method is: treat the biochar with water vapor for 10 minutes, and then mix it with the modifier according to the volume ratio of 1:1 After adding into the reactor, the modifier is a mixture solution containing 1wt% acrylic acid, 0.2wt% alkylsulfonate, 0.1wt% TAED; mixing and stirring, the time is controlled at 10 minutes, and the heating rate is 8°C Carry out per minute until the temperature reaches 60°C, and keep it at a constant temperature for 1 hour; then continue to increase the temperature, control the heating rate at 5°C/min, until the temperature reaches 90°C, and keep it at a constant temperature for 1.2 hours before discharging; then wash repeatedly with water until The pH value is 6; during the drying process, the temperature is controlled at 130°C, and the water content is controlled at 1%, to obtain modified biochar. After modification, the adsorption capacity of biochar to rural organic wastewater can be increased;

3) Rural organic wastewater pretreatment: pretreat rural organic wastewater by hydrolytic acidification, UASB reactor, IC reactor, SBR, AAO, ultrasonic treatment and other wastewater treatment methods; hydrolytic acidification treatment can reduce the suspended solids of wastewater and improve the reliability Biochemical, UASB reactor, IC reactor, SBR, AAO, ultrasonic treatment and other wastewater treatment methods can further reduce suspended solids and macromolecular substances in water;

4) Enrichment of nutrients by biochar: Add the modified biochar obtained in step 2) to the rural organic wastewater pretreated in step 3), and the modified biochar will adsorb the wastewater. The method is a fixed bed method, which controls the flow rate of rural organic wastewater through the fixed bed to 0.5BV/h, and at the same time prevents the biochar from flowing out with the water flow;

5) Granulation: add a binder to the adsorbed modified biochar at a weight ratio of 1:0.1, the binder is a mixture of starch and clay at a ratio of 1:1, and prepare granules by rolling granulation Granular with uniform diameter, that is, a biomass charcoal-based slow-release organic fertilizer.

Example 2

Considering the mixture of straw, grass and domestic waste as agricultural solid waste, its moisture content is 1wt%, and using septic tank effluent and breeding wastewater as rural organic sewage to prepare biomass charcoal-based slow-release organic fertilizer. The specific method is as follows:

Biochar with high adsorption capacity is prepared by pyrolyzing agricultural solid waste at high temperature, then adsorbing treated rural organic wastewater, and finally preparing biochar-based slow-release organic fertilizer, which specifically includes the following steps:

1) Preparation of biochar: crush the agricultural solid waste to 5cm, put it in a tube furnace, pyrolyze and carbonize it at a temperature of 550°C, and process it for 9 hours to make biochar, and use pyrolysis protection gas is nitrogen;

2) Biomass charcoal modification: modify the biochar obtained in step 1), the treatment method is: treat the biochar with water vapor for 20 minutes, and then mix it with the modifier according to the volume ratio of 1:3 After adding into the reactor, the modifying agent is a mixture solution containing 2wt% acrylic acid, 0.35wt% alkylsulfonate, 0.55wt% TAED; mixing and stirring, the time is controlled at 15 minutes, and the heating rate is 9°C Carry out per minute until the temperature reaches 70°C, keep at a constant temperature for 2.25 hours; then continue to heat up, control the heating rate at 7°C/min, until the temperature reaches 95°C, and keep at a constant temperature for 2.9 hours before discharging; then wash repeatedly with water until The pH value is 6.8; during the drying process, the temperature is controlled at 135°C, and the water content is controlled at 1.5%, to obtain modified biochar. After modification, the adsorption capacity of biochar to rural organic wastewater can be increased;

3) Rural organic wastewater pretreatment: pretreat rural organic wastewater by hydrolytic acidification, UASB reactor, IC reactor, SBR, AAO, ultrasonic treatment and other wastewater treatment methods; hydrolytic acidification treatment can reduce the suspended solids of wastewater and improve the reliability Biochemical, UASB reactor, IC reactor, SBR, AAO, ultrasonic treatment and other wastewater treatment methods can further reduce suspended solids and macromolecular substances in water;

4) Enrichment of nutrients by biochar: Add the modified biochar obtained in step 2) to the rural organic wastewater pretreated in step 3), and the modified biochar will adsorb the wastewater. The method is a fluidized bed method, which controls the flow rate of rural organic wastewater through the fluidized bed to 4BV/h, and at the same time prevents the biochar from flowing out with the water;

6) Granulation: Add a binder to the adsorbed modified biochar in a weight ratio of 1:5, the binder is a mixture of zeolite and bentonite in a weight ratio of 1:2, and granulate by extrusion The method is used to prepare granules with uniform particle size to obtain the biomass charcoal-based slow-release organic fertilizer.

Example 3

Taking rice straw and livestock manure biogas residue as agricultural solid waste, its water content is 1wt%, and using agricultural by-product processing wastewater and household domestic wastewater as rural organic sewage to prepare biomass charcoal-based slow-release organic fertilizer. The specific method is as follows:

Biochar with high adsorption capacity is prepared by pyrolyzing agricultural solid waste at high temperature, then adsorbing treated rural organic wastewater, and finally preparing biochar-based slow-release organic fertilizer, which specifically includes the following steps:

1) Preparation of biochar: crush agricultural solid waste to 10cm, put it in a tube furnace, pyrolyze and carbonize it at a temperature of 800°C, and process it for 10 hours to make biochar, and use pyrolysis protection gas is nitrogen;

2) Biomass charcoal modification: modify the biochar obtained in step 1), the treatment method is: treat the biochar with water vapor for 30min, and then mix it with the modifying agent according to the volume ratio of 1:5 After adding in the reactor, the modifying agent is a mixture solution containing 3wt% acrylic acid, 0.5wt% alkylsulfonate, 1wt% TAED; mixing and stirring, the time is controlled at 20 minutes, and the heating rate is 10 ℃/ Minutes until the temperature reaches the range of 80°C, keep the constant temperature for 3.5 hours; then continue to increase the temperature, the heating rate is controlled at 10°C/min, until the temperature reaches the range of 100°C, and keep the constant temperature for 4.6 hours before discharging; then wash repeatedly with water, Until the pH value is 7.5; in the drying process, the temperature is controlled in the range of 140 ° C, and the water content is controlled at 2%, to obtain modified biochar. After modification, the adsorption capacity of biochar to rural organic wastewater can be increased;

3) Rural organic wastewater pretreatment: pretreat rural organic wastewater by hydrolytic acidification, UASB reactor, IC reactor, SBR, AAO, ultrasonic treatment and other wastewater treatment methods; hydrolytic acidification treatment can reduce the suspended solids of wastewater and improve the reliability Biochemical, UASB reactor, IC reactor, SBR, AAO, ultrasonic treatment and other wastewater treatment methods can further reduce suspended solids and macromolecular substances in water;

4) Enrichment of nutrients by biochar: Add the modified biochar obtained in step 2) to the rural organic wastewater pretreated in step 3), and the modified biochar will adsorb the wastewater. The method is a fixed bed method, which controls the flow rate of rural organic wastewater through the fixed bed to 8BV/h, and at the same time prevents the biochar from flowing out with the water;

7) Granulation: add a binder to the adsorbed modified biochar in a weight ratio of 1:10, the binder is kaolin, and prepare it into a granular shape with uniform particle size by compression granulation, to obtain Biochar-based slow-release organic fertilizer.

Although the present invention has been disclosed as above with the embodiments, it is not intended to limit the scope of protection of the present invention. Any changes and modifications made by those skilled in the art without departing from the concept and scope of the present invention shall be Belong to the protection scope of the present invention.

Claims (7)

1. A method for preparing biomass charcoal-based slow-release organic fertilizer with agricultural solid waste, characterized in that, the biochar with high adsorption capacity is prepared after the agricultural solid waste is pyrolyzed at high temperature, and then adsorbed after treatment rural organic wastewater, and finally prepare biomass charcoal-based slow-release organic fertilizer, which specifically includes the following steps: 1) Preparation of biochar: crush agricultural solid waste to 0.5-10cm, put it in a tube furnace, pyrolyze and carbonize it at a temperature of 300-800℃, and process it for 8-10h to make biomass Charcoal, pyrolysis protection gas is nitrogen; 2) Modification of biochar: modifying the biochar obtained in step 1) with a modifier to obtain modified biochar; 3) Rural organic wastewater pretreatment: The rural organic wastewater is pretreated by hydrolytic acidification, UASB reactor, IC reactor, SBR, AAO, ultrasonic treatment and other wastewater treatment methods. 4) Enrichment of nutrients by biochar: Add the modified biochar obtained in step 2) to the rural organic wastewater pretreated in step 3), and the modified biochar will adsorb the wastewater. The method can be fixed bed, fluidized bed and other methods, and the flow rate of rural organic wastewater passing through the fixed bed or fluidized bed is controlled to be 0.5-8BV/h, and at the same time, the biochar is prevented from flowing out with the water flow. 5) Granulation: add a binder to the adsorbed modified biochar in a weight ratio of 1:(0.1-10) to prepare a granular shape with uniform particle size, and obtain a biochar-based slow-release organic fertilizer . 2. A kind of method for preparing biomass charcoal-based slow-release organic fertilizer with agricultural solid waste as claimed in claim 1, is characterized in that: described agricultural solid waste is selected from straw, grass, house refuse, livestock manure marsh One or more of the slag. 3. A method for preparing biomass charcoal-based slow-release organic fertilizer with agricultural solid wastes as claimed in claim 1, 2, characterized in that: the moisture content of said agricultural solid wastes is 1wt%. 4. A kind of method for preparing biomass charcoal-based slow-release organic fertilizer with agricultural solid waste as claimed in claim 1, is characterized in that: described rural organic sewage is nontoxic and harmless high-concentration organic waste water, is selected from One or more of agricultural by-product processing wastewater, septic tank effluent, farming wastewater, and wastewater related to family life. 5. A method of preparing biomass charcoal-based slow-release organic fertilizer with agricultural solid waste as claimed in claim 1, characterized in that: the way of enriching nutrients by said biochar can be fixed bed, fluidized One or more of bed, trickling bed, etc. 6. A kind of method for preparing biomass charcoal-based slow-release organic fertilizer with agricultural solid waste as claimed in claim 1, is characterized in that: described binding agent can be starch, clay, zeolite, bentonite, kaolin etc. one or more of them. 7. A kind of method for preparing biomass charcoal-based slow-release organic fertilizer with agricultural solid waste as claimed in claim 1, is characterized in that: described granulation method can be rolling granulation, stirring granulation, compression granulation , extrusion granulation, dry granulation, fluidized bed granulation, sintering and roasting and other methods.