Biochar-based ecological brick special for farmland ditch and preparation method of charcoal-based ecological brick

Abstract

The invention relates to the technical field of ecological environment-friendly materials, and discloses a special biochar-based ecological brick for farmland ditches and a preparation method thereof, and the preparation method comprises the following steps: S1, respectively drying, crushing and mixing lignin-rich biomass, silicon-rich biomass and nitrogen-rich biomass; s2, inoculating the materials mixed in the step S1 with a functional microbial agent, adjusting the water content, and composting at normal temperature; s3, diluted hydrochloric acid and the steel slag are mixed, stirred and left to stand; s4, mixing the material obtained in S2 with the material obtained in S3, and drying; s5, performing two-stage stepped anaerobic pyrolysis on the material obtained in the step S4, and cooling to obtain biochar; and S6, stirring the charcoal obtained in the step S5, cement, recycled aggregate, an additive and water, uniformly mixing, injecting into a mold, carrying out vibration molding, demolding, and curing to obtain the special charcoal-based ecological brick for the farmland ditch. The prepared ecological brick has the advantages of being high in strength, high in purification capacity, remarkable in ecological benefit and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of ecological and environmental protection materials, and particularly relates to a special biochar-based ecological brick for farmland ditches and a preparation method thereof. Background Art

[0002] Traditional ditches are mostly built with concrete or masonry, which have problems such as poor water permeability, low ecological benefits, and easy water pollution. In recent years, ecological bricks have gradually emerged, mainly made of environmentally friendly industrial solid wastes, including materials such as sludge, waste glass, ceramics, cinder, and steel slag. These materials are made through processes such as mixing with curing agents and molding, significantly reducing pollution and resource waste, and conforming to the concept of green environmental protection. They use water-permeable materials and can effectively purify water quality, conserve water sources, and improve the ecological environment. However, existing ecological bricks still have problems such as insufficient strength, poor durability, and limited purification effect.

[0003] Biochar is a carbon-rich material produced by pyrolysis of biomass under anoxic conditions, which has advantages such as a large specific surface area, developed pore structure, and strong adsorption capacity, and has broad application prospects in the field of environmental remediation. Applying biochar to the preparation of ecological bricks can effectively improve the purification ability and ecological benefits of farmland ditches. However, due to the negatively charged enrichment state on the surface of conventionally prepared biochar, its adsorption capacity for anions (such as nitrate and phosphate) is limited. Summary of the Invention

[0004] Object of the Invention: Aiming at the problems existing in the prior art, the present invention provides a special biochar-based ecological brick for farmland ditches and a preparation method thereof. By mixing lignin-rich and silicon-containing biomass, nitrogen-rich biomass with acid-pretreated steel slag, and subjecting them to anaerobic pyrolysis to obtain a biochar material, and then mixing it with cement, aggregate, additives, etc., and pressing and curing to prepare a biochar-based ecological brick. The ecological brick prepared by the present invention has advantages such as high strength, strong purification ability, and remarkable ecological benefits.

[0005] Technical Solution: On the one hand, the present invention provides a preparation method of a special biochar-based ecological brick for farmland ditches, including the following steps: S1. Drying and pulverizing lignin-rich and silicon-containing biomass and nitrogen-rich biomass respectively, and mixing them; S2. Adjusting the water content of the mixed material in S1 to 30-40% and then inoculating with a functional microbial inoculant, and performing composting at room temperature; S3. Mixing dilute hydrochloric acid and steel slag, stirring, and then standing for a period of time; S4. Mixing the material obtained in S2 and the material obtained in S3, and drying; S5. Pyrolyze the material obtained in S4 under anaerobic conditions and then cool it to obtain biochar. Among them, the specific conditions for the anaerobic pyrolysis are as follows: Under the condition of passing nitrogen, first heat it at a rate of 5-10 °C / min to 150-180 °C and keep it for 30-60 min; then continue to heat it at a rate of 10-20 °C / min to 550-650 °C and keep it for 120-150 min. -1 rate to 150 - 180 °C, and the holding time is 30 - 60 min; then continue to heat at a rate of 10 - 20 °C / min -1 to 550 - 650 °C, and the holding time is 120 - 150 min; S6. Stir and mix the biochar, cement, recycled aggregate, additive and water obtained in S5 evenly to form a uniform slurry; inject the slurry into a mold, vibrate it to form a shape, demold it, and cure it for 10 - 12 days under standard curing conditions to obtain a biochar-based ecological brick for farmland ditches.

[0006] Further, in S1, the lignin-rich and silicon biomass has a lignin content of more than 30% and a silicon content of more than 15%; In S1, the nitrogen-rich biomass has a nitrogen content of more than 3%; In S1, the lignin-rich and silicon biomass and the nitrogen-rich biomass are mixed according to a C / N ratio of 28:1 - 32:1.

[0007] Preferably, the lignin-rich and silicon biomass is sawdust, nut shells, etc.; the nitrogen-rich biomass is livestock manure, sludge, diatoms, etc.

[0008] Preferably, the sawdust is the sawdust after processing of wood such as beech, walnut, oak, etc.; the nut shells are walnut shells, almond shells, coconut shells, etc.; the livestock manure is pig manure, chicken manure, duck manure, etc.; the sludge is municipal sludge, non-polluted industrial sludge, etc.; the microalgae are green algae, diatoms, cyanobacteria or chrysophytes, etc.

[0009] Further, in S2, the functional microbial inoculum is a mixed bacterium of cellulose-degrading bacteria and hemicellulose-decomposing bacteria, and the mixing ratio is 1:1 - 1.5:1.

[0010] Further, the addition amount of the functional microbial inoculum in the material mixed in S1 is 2.0 - 4.0×10 9 cfu / kg.

[0011] Preferably, in S2, the specific operation includes inoculating the mixed bacterium of cellulose-degrading bacteria and hemicellulose-decomposing bacteria into the material mixed in S1, adjusting the water content to 30 - 40%, and then controlling the temperature at 30 - 35 °C by blowing air and culturing it in a windrow with a nano-permeable membrane until the C / N ratio in the material reaches less than 15:1 (about 4 - 6 days).

[0012] Preferably, the cellulose-degrading bacteria are Trichoderma reesei, Trichoderma harzianum, etc.; the hemicellulose-decomposing bacteria are Trichoderma lignorum, Trichoderma pseudokoningii, Aspergillus niger, etc.

[0013] Further, the mixing of the dilute hydrochloric acid and the steel slag in S3 is specifically as follows: Dilute hydrochloric acid with a concentration of 0.1 - 0.3 moL / L is added to the steel slag until the pH of the mixture reaches 4.0 - 5.0.

[0014] Further, in S4, the materials obtained in S2 and the materials obtained in S3 are mixed according to the standards that the Si content is 10 - 15%, the Fe content is 4 - 5%, the total content of Ca and Mg is 10 - 15%, and the N / Cl ratio is 4:1 - 6:1.

[0015] Preferably, in S4, the drying is specifically carried out by the hot drying method until the water content of the material reaches less than 5%.

[0016] Further, in S6, by weight, the proportions of the components in the slurry are as follows: The biochar obtained in S5: 5 - 10 parts, cement: 35 - 40 parts, recycled aggregate: 30 - 40 parts, additive: 10 - 15 parts, water: appropriate amount.

[0017] Further, in S6, the recycled aggregate is processed from waste concrete through processes such as crushing and screening, and the particle size is 2 - 4 mm; In S6, the additive is a mixture of a water - reducing agent, an early - strength agent, a waterproofing agent, and an air - entraining agent, and the mixing ratio is 3:2:3:2 or 2.5:2.5:2.5:2.5.

[0018] Preferably, in S1, the crushed material is screened through a 2 - 4 mm sieve.

[0019] On the other hand, the present invention provides a special biochar - based ecological brick for farmland ditches prepared by the method described in any one of the above.

[0020] Beneficial effects: The operation of the present invention is simple and the cost is low. The special biochar - based ecological brick for farmland ditches prepared has extremely high strength. At the same time, elements such as carbon, nitrogen, iron, calcium, magnesium, and silicon in the ecological brick exist in the form of effectively adsorbing nitrate and phosphate, and can effectively adsorb nitrate and phosphate. It not only solves the environmental pollution problem of industrial waste, but also solves the problem of insufficient water purification ability of traditional ecological bricks, and has great application prospects in the construction of farmland ditches. Compared with the prior art, the specific beneficial effects are as follows: (1) The present invention uses cellulose - degrading bacteria and hemicellulose - decomposing bacteria to treat the mixture of lignin - rich, silicon - rich and nitrogen - rich biomass at room temperature, which can enrich lignin, silicon and nitrogen, and has the advantages of energy conservation and environmental protection compared with chemical treatment methods.

[0021] (2) Among the biochar raw materials selected in the present invention, lignin can form more stable aromatic structures during pyrolysis, while silicon forms calcium magnesium silicoaluminate with metals in steel slag. The formation of both can greatly improve the hardness of biochar particles, thereby forming ecological bricks with extremely high strength.

[0022] (3) After being treated with dilute hydrochloric acid, metal oxides in steel slag will produce a large amount of ionic iron, calcium, magnesium and other elements. During pyrolysis, ionic calcium, magnesium, iron, etc. catalyze biomass to generate biochar with rich microporous structures, which can adsorb nitrate nitrogen and phosphate in water by physical action.

[0023] (4) In the present invention, nitrogen, lignin in biomass and chlorine in steel slag treated with dilute hydrochloric acid can form stable quaternary ammonium chloride functional groups for adsorbing nitrate and phosphate under anaerobic high-temperature treatment at 150 - 180°C, which can effectively adsorb nitrate and phosphate; under anaerobic high-temperature treatment at 550 - 650°C, ionic calcium and magnesium can form calcium and magnesium oxides or hydroxides, and then can adsorb phosphate by precipitation, while ionic iron reacts with lignin in biomass to generate stable carbon-iron-oxygen functional groups (C-O-Fe-OH), which can effectively adsorb nitrate and phosphate; through two-stage stepwise pyrolysis reaction, the steel slag is turned from waste into treasure, and the production cost is also reduced to the greatest extent.

[0024] (5) The biochar prepared in the present invention can replace 10 - 20% of cement, which can not only improve the strength of ecological bricks, but also effectively achieve carbon sequestration, with significant ecological benefits. Specific Embodiments

[0025] The present invention will be introduced in detail below in combination with the embodiments.

[0026] Embodiment 1: Performance comparison of biochar prepared from lignin-rich and silicon-containing biomass with different pretreatments S1. Dry and crush walnut shells and pig manure respectively, and then pass through a 4-mm sieve, and mix them according to a C / N ratio of 30:1; S2. Inoculate the mixed material in S1 with a mixed bacteria of cellulose-degrading bacteria and hemicellulose-decomposing bacteria (4.0×10 9 cfu / kg), adjust the water content to 30%, and then control the temperature at 30 - 35°C by blowing air for pile-type cultivation with a nano-permeable membrane until the C / N ratio in the material reaches less than 15:1 (5 days); S3. Add 0.1 moL / L dilute hydrochloric acid to steel slag until the pH of the mixture reaches 4.0, stir for 1 hour and then stand for 8 hours; S4. Mix the material obtained in S2 and the material obtained in S3 according to the standards of 10% Si content, 4% Fe content, 10% total Ca and Mg content, and an N / Cl ratio of 4:11, and use the hot drying method until the water content of the material reaches less than 5%; S5. Pyrolyze the material obtained in S4 anaerobically and cool it to obtain biochar; among them, the specific conditions for anaerobic pyrolysis are: while maintaining an anaerobic state by introducing high-purity nitrogen at a rate of 200 mL / min / kg of raw material, heat it at a rate of 10 °C / min -1 to 160 °C, hold for 30 minutes, and then continue to heat it at a rate of 10 °C / min -1 to 650 °C and hold for 120 minutes.

[0027] Under other unchanged conditions, in S2, the mixed material in S1 is treated with a mixed enzyme of cellulase and hemicellulase (enzymatic hydrolysis, enzyme addition amount is 50 IFPU / g), treated with an acid solution (acid hydrolysis, 4% sulfuric acid, addition amount 10 mL / g), and untreated (control) as a comparison; and its hardness, density, compressive strength and adsorption capacity are measured. The results are shown in Table 1.

[0028]

[0029] As can be seen from Table 1, the density, hardness, compressive strength, and the ability to adsorb nitrate and phosphate of the biochar prepared from the biomass after microbial treatment are all better than those of the control and other treatments.

[0030] Embodiment 2: Influence of pyrolysis of steel slag treated with different acids on the performance of biochar

[0031] S1. Dry and crush walnut shells and pig manure respectively, and pass through a 4-mm sieve, and mix them according to a C / N ratio of 32:1; S2. Inoculate the mixed material in S1 with a mixed bacterium of cellulose-degrading bacteria and hemicellulose-decomposing bacteria (4.0×10 9 cfu / kg), adjust the water content to 30%, and then control the temperature at 30 - 35 °C by blowing air and cultivate it in a strip stack covered with a nano-permeable membrane until the C / N ratio in the material reaches less than 15:1 (about 4 - 6 days); S3. Add 0.1 moL / L dilute hydrochloric acid to steel slag until the pH of the mixture reaches 4.0, stir for 1 hour and then stand for 8 hours; at the same time, set the dilute hydrochloric acid to the same concentration of nitric acid, sulfuric acid and no treatment (control) as a comparison; S4. Mix the material obtained in S2 and the material obtained in S3 according to the standards of 10% Si content, 4% Fe content, 10% total Ca and Mg content, and an N / Cl ratio of 4:11, and use the hot drying method until the water content of the material reaches less than 5%; S5. Pyrolyze the material obtained in S4 under anaerobic conditions and then cool it to obtain biochar. Among them, the specific conditions for anaerobic pyrolysis are as follows: While maintaining an anaerobic state by introducing high-purity nitrogen at a rate of 200 mL / min / kg of raw material, heat it at a rate of 10 °C / min to 160 °C, keep it for 30 min, and then continue to heat it at a rate of 10 °C / min to 650 °C and keep it for 120 min. Finally, measure the specific surface area, the number of quaternary ammonium chloride and Fe-OH functional groups, and the adsorption capacities for nitrate nitrogen and phosphate of the biochar. The results are shown in Table 2. -1 at a rate of -1 to 650 °C and keep it for 120 min. Finally, measure the specific surface area, the number of quaternary ammonium chloride and Fe-OH functional groups, and the adsorption capacities for nitrate nitrogen and phosphate of the biochar. The results are shown in Table 2.

[0032]

[0033] As can be seen from Table 2, the biochar prepared by co-pyrolysis of steel slag treated with dilute hydrochloric acid and biomass is superior to other acid treatments in all aspects.

[0034] Embodiment 3: Comparison of the adsorption effects of biochars prepared from different raw material combinations on nitrate and phosphate

[0035] S1. Dry and crush coconut shells and pig manure separately, and then pass them through a 4-mm sieve and mix them according to a C / N ratio of 32:1. S2. Inoculate the mixed material in S1 with a mixed bacterium of cellulose-degrading bacteria and hemicellulose-decomposing bacteria (4.0×10 9 cfu / kg), adjust the water content to 30%, and then control the temperature at 30 - 35 °C by blowing air and culture it in a windrow covered with a nano-permeable membrane until the C / N ratio in the material reaches below 15:1 (about 4 - 6 days). S3. Add 0.1 moL / L dilute hydrochloric acid to steel slag until the pH of the mixture reaches 4.0, stir for 1 hour and then let it stand for 8 hours. S4. Mix the material obtained in S2 and the material obtained in S3 according to the standards of 10% Si content, 4% Fe content, 10% total content of Ca and Mg, and an N / Cl ratio of 4:11, and use the hot drying method until the water content of the material reaches below 5%. S5. Pyrolyze the material obtained in S4 under anaerobic conditions and then cool it to obtain biochar. Among them, the specific conditions for anaerobic pyrolysis are as follows: While maintaining an anaerobic state by introducing high-purity nitrogen at a rate of 200 mL / min / kg of raw material, heat it at a rate of 10 °C / min -1 to 160 °C, keep it for 30 min, and then continue to heat it at a rate of 10 °C / min -1 to 650 °C and keep it for 120 min.

[0036] Under other unchanged conditions, biochar was prepared using straw, coconut shell, straw + pig manure, coconut shell + pig manure, and straw + pig manure + steel slag as raw material combinations respectively; finally, the hardness, compressive strength, and the adsorption capacities for nitrate and phosphate of the biochar were measured, and the results are shown in Table 3.

[0037]

[0038] As can be seen from Table 3, the biochar prepared with coconut shell + pig manure + steel slag as the raw material is superior to other raw materials in all aspects.

[0039] Embodiment 4: Performance comparison of ecological bricks prepared by mixing biochar with other materials

[0040] S1. The walnut shell and pig manure were dried, crushed respectively, and then sieved through a 4 mm sieve, and mixed according to a C / N ratio of 32:1. S2. The mixed materials in S1 were inoculated with a mixed bacterium of cellulose-degrading bacteria and hemicellulose-decomposing bacteria (4.0×10 9 cfu / kg), the water content was adjusted to 30%, and then the temperature was controlled at 30 - 35 °C by blowing air for strip stacking cultivation with a nano-permeable membrane until the C / N ratio in the materials reached below 15:1 (about 4 - 6 days). S3. 0.1 moL / L dilute hydrochloric acid was added to the steel slag until the pH of the mixture reached 4.0, stirred for 1 hour and then left to stand for 8 hours. S4. The materials obtained in S2 and the materials obtained in S3 were mixed according to the standards of 10% Si content, 4% Fe content, 10% total content of Ca and Mg, and N / Cl ratio of 4:11, and dried by hot drying until the water content of the materials reached below 5%. S5. The materials obtained in S4 were pyrolyzed anaerobically and cooled to obtain biochar; among them, the specific conditions for anaerobic pyrolysis were: while maintaining an anaerobic state by introducing high-purity nitrogen at a rate of 200 mL / min / kg of raw material, heating was carried out at a rate of 10 °C / min to 160 °C, the holding time was 30 min, and then heating was continued at a rate of 10 °C / min -1 to 650 °C, and the holding time was 120 min. -1 The waste concrete was processed through processes such as crushing and screening to form recycled aggregates with a particle size of 4 mm, and a water-reducing agent, an early-strength agent, a waterproofing agent, and an air-entraining agent were mixed according to a mass ratio of 3:2:3:2 to form an additive; by weight, according to the proportions of biochar, cement, recycled aggregates, and additive in Table 4, each component was stirred and mixed evenly to form a uniform slurry; the slurry was injected into a mold and vibrated to form; after demolding, it was cured under standard curing conditions for 10 days to obtain the special biochar-based ecological bricks for farmland ditches. Finally, the hardness, compressive strength, and the adsorption capacities for nitrate and phosphate of the ecological bricks were measured, and the results are shown in Table 4.

[0041]

[0042] As can be seen from Table 4, the optimal formulation ratio of the ecological brick is as follows: biochar: 10 - 20 parts, cement: 30 - 40 parts, aggregate: 30 - 40 parts, additive: 10 - 15 parts.

[0043] Embodiment 5: Comparison of biochar-based ecological bricks for farmland ditches prepared from different biomass raw materials

[0044] S1. Dry and crush oak sawdust and green algae respectively, and then pass them through a 4-mm sieve, and mix them according to a C / N ratio of 28:1; S2. Inoculate the mixed material in S1 with a mixed bacteria of cellulose-degrading bacteria and hemicellulose-decomposing bacteria (4.0×10 9 cfu / kg), adjust the water content to 30%, and then control the temperature at 30 - 35 °C by blowing air and cultivate in a strip stack covered with a nano-permeable membrane until the C / N ratio in the material reaches below 15:1 (about 4 - 6 days); S3. Add 0.1 moL / L dilute hydrochloric acid to steel slag until the pH of the mixture reaches 4.0, stir for 1 hour and then stand for 8 hours; S4. Mix the material obtained in S2 and the material obtained in S3 according to the standards of 10% Si content, 4% Fe content, 10% total content of Ca and Mg, and N / Cl ratio of 4:11, and use the hot drying method until the water content of the material reaches below 5%; S5. Pyrolyze the material obtained in S4 anaerobically and cool it to obtain biochar; among them, the specific conditions for anaerobic pyrolysis are: while maintaining an anaerobic state by introducing high-purity nitrogen at a rate of 200 mL / min / kg of raw material, raise the temperature at a rate of 10 °C / min -1 to 160 °C, keep the time for 30 min, and then continue to raise the temperature at a rate of 10 °C / min -1 to 650 °C, and keep the time for 120 min; S6. Process waste concrete through processes such as crushing and screening to form recycled aggregate with a particle size of 4 mm, and mix water-reducing agent, early-strength agent, waterproof agent and air-entraining agent according to a mass ratio of 3:2:3:2 to form an additive; by weight, take 10 parts of the biochar obtained in S5, 35 parts of cement, 40 parts of recycled aggregate, 15 parts of additive, and an appropriate amount of water, stir and mix the components evenly to form a uniform slurry; inject the slurry into a mold and vibrate to form; after demolding, cure for 10 days under standard curing conditions to obtain the biochar-based ecological brick for farmland ditches.

[0045] With other conditions remaining unchanged, biochar-based ecological bricks were prepared using corn straw, oak sawdust, green algae, and corn straw + green algae as raw materials in S1 respectively. Finally, the hardness, compressive strength, and the adsorption capacity for nitrate and phosphate of the ecological bricks were measured, and the results are shown in Table 5.

[0046]

[0047] As can be seen from Table 5, the ecological bricks prepared with oak sawdust + green algae as the biochar raw material have the best indicators in all aspects.

[0048] Embodiment 6: Comparison of preparation methods of biochar-based ecological bricks for farmland ditches under different pyrolysis conditions

[0049] S1. Dry and crush hazelnut shells and municipal sludge respectively, and then pass them through a 4-mm sieve, and mix them according to a C / N ratio of 28:1; S2. Inoculate the mixed material in S1 with a mixed bacterium of cellulose-degrading bacteria and hemicellulose-decomposing bacteria (4.0×10 9 cfu / kg), adjust the water content to 30%, and then control the temperature at 30 - 35 °C by blowing air to carry out strip stacking cultivation with a nano-permeable membrane until the C / N ratio in the material reaches below 15:1 (about 4 - 6 days); S3. Add 0.2 moL / L dilute hydrochloric acid to steel slag until the pH of the mixture reaches 5.0, stir for 2 hours and then stand still for 10 hours; S4. Mix the material obtained in S2 and the material obtained in S3 according to the standards of 10% Si content, 4% Fe content, 10% total content of Ca and Mg, and N / Cl ratio of 4:11, and use the hot drying method until the water content of the material reaches below 5%; S5. Pyrolyze the material obtained in S4 under anaerobic conditions and then cool it to obtain biochar. Among them, the specific conditions for anaerobic pyrolysis are as follows: while maintaining an anaerobic state by introducing high-purity nitrogen at a rate of 300 mL / min / kg of raw material, heat it at a rate of 10 °C / min -1 to 160 °C, keep the temperature for 30 - 60 min, and then continue to heat it at a rate of 10 °C / min -1 to 650 °C, and keep the temperature for 120 min; or heat it at a rate of 10 °C / min -1 to 650 °C, and keep the temperature for 120 min; or heat it at a rate of 10 °C / min -1 to 160 °C, keep the temperature for 30 - 60 min, and then continue to heat it at a rate of 10 °C / min -1 to 400 °C, and keep the temperature for 120 min; or heat it at a rate of 10 °C / min -1 to 160 °C, keep the temperature for 30 - 60 min, and then continue to heat it at a rate of 10 °C / min -1The temperature is raised to 800 °C at a certain rate and held for 120 min.

[0050] S6. Process the waste concrete through processes such as crushing and screening to form recycled aggregates with a particle size of 4 mm. Mix water-reducing agent, early-strength agent, waterproof agent and air-entraining agent in a mass ratio of 3:2:3:2 to form an additive. By weight, take the biochar obtained in S5: 10 parts, cement: 35 parts, recycled aggregates: 40 parts, additive: 15 parts, water: appropriate amount. Stir and mix the components evenly to form a uniform slurry. Inject the slurry into a mold and vibrate to form. After demolding, cure for 10 days under standard curing conditions to obtain the biochar-based ecological bricks for farmland ditches. Finally, measure the hardness, compressive strength of the ecological bricks and their adsorption capacity for nitrate and phosphate. The results are shown in Table 6.

[0051]

[0052] As can be seen from Table 6, in terms of the comparison of various indicators of the ecological bricks, two-stage programmed temperature pyrolysis is better than single-stage programmed temperature pyrolysis, and the combination of 160 °C + 650 °C is better than other combinations.

[0053] In summary, the present invention provides a biochar-based ecological brick for ecological ditches and its preparation method. The ecological brick has the advantages of high strength, good water permeability, strong purification ability, significant ecological benefits, etc., and can be widely used in the fields of ecological ditch construction, river regulation, wetland restoration, etc.

[0054] The above embodiments are only used to illustrate the technical concept and characteristics of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A preparation method of a special biochar-based ecological brick for farmland ditches, characterized in that, It includes the following steps: S1. Dry and crush the lignin-rich material, silicon biomass, and nitrogen-rich biomass respectively, and then mix them; S2. Adjust the water content of the mixed material in S1 to 30-40%, then inoculate with a functional microbial inoculant and carry out composting at room temperature; S3. Mix dilute hydrochloric acid and steel slag, stir, and then let it stand for a period of time; S4. Dry the mixture obtained from S2 and the mixture obtained from S3 after mixing; S5. Pyrolyze and cool the material obtained in S4 under anaerobic conditions to obtain biochar; wherein, the specific conditions for the anaerobic pyrolysis are as follows: under the condition of nitrogen passing, first heat up at a rate of 5-10 °C / min -1 to 150-180 °C, and keep for 30-60 min; then continue to heat up at a rate of 10-20 °C / min -1 to 550-650 °C, and keep for 120-150 min; S6. Stir and mix the biochar obtained from S5, cement, recycled aggregate, additive, and water evenly to form a uniform slurry; inject the slurry into a mold, vibrate and form, demold, and cure for 10-12 days under standard curing conditions to obtain a biochar-based ecological brick for farmland ditches.

2. The preparation method of the special biochar-based ecological brick for farmland ditches according to claim 1, characterized in that: In S1, the lignin content in the lignin-rich material and silicon biomass is more than 30%, and the silicon content is more than 15%; In S1, the nitrogen content in the nitrogen-rich biomass is more than 3%; In S1, the lignin-rich material, silicon biomass, and nitrogen-rich biomass are mixed according to a C / N ratio of 28:1-32:

1.

3. The preparation method of the special biochar-based ecological brick for farmland ditches according to claim 1, characterized in that: In S2, the functional microbial inoculant is a mixed bacterium of cellulose-degrading bacteria and hemicellulose-decomposing bacteria, and the mixing ratio is 1:1-1.5:

1.

4. The preparation method of the special biochar-based ecological brick for farmland ditches according to claim 3, characterized in that: The addition amount of the functional microbial inoculum in the material after mixing in S1 is 2.0 - 4.0×10 9 cfu / kg.

5. The preparation method of the special biochar-based ecological brick for farmland ditches according to claim 1, characterized in that: The specific mixing of dilute hydrochloric acid and steel slag in S3 is: add 0.1-0.3 moL / L of dilute hydrochloric acid to steel slag until the pH of the mixture reaches 4.0-5.

0.

6. The preparation method of the special biochar-based ecological brick for farmland ditches according to claim 1, characterized in that: In S4, mix the material obtained from S2 and the material obtained from S3 according to the standard that the Si content is 10-15%, the Fe content is 4-5%, the total content of Ca and Mg is 10-15%, and the N / Cl ratio is 4:1-6:

1.

7. The preparation method of the special biochar-based ecological brick for farmland ditches according to claim 1, characterized in that: In S6, by weight, the proportions of the components in the slurry are: biochar obtained from S5: 10-15 parts, cement: 35-40 parts, recycled aggregate: 30-40 parts, additive: 10-15 parts, water: appropriate amount.

8. The preparation method of the special biochar-based ecological brick for farmland ditches according to claim 1, characterized in that: In S6, the recycled aggregate is processed from waste concrete through processes such as crushing and screening, and the particle size is 2-4 mm; In S6, the additive is a mixture of water reducing agent, early strength agent, waterproof agent, and air-entraining agent, and its mixing ratio is 3:2:3:2 or 2.5:2.5:2.5:2.

5.

9. The preparation method of the special biochar-based ecological brick for farmland ditches according to any one of claims 1-8, characterized in that: In S1, the crushed material passes through a 2-4 mm sieve.

10. A biochar-based ecological brick for farmland ditches prepared by the method according to any one of claims 1-9.

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