Method for comprehensively utilizing sugarcane leaves

Abstract

The invention discloses a method for comprehensively utilizing sugarcane leaves, and particularly relates to the field of resource utilization. Comprising the following steps: S1, performing fiber directional dissociation and microorganism composite treatment on sugarcane leaves, and controlling the fiber length to be less than or equal to 5cm and the lignin degradation rate to be more than or equal to 30%; s2, dividing the pretreated sugarcane leaves into a short fiber component, a medium and long fiber component and a soluble component on the basis of fiber length and chemical component difference; s3, the short fiber components are used for preparing a slow-release organic fertilizer, the medium and long fiber components are used for feed processing, and the soluble components are used for extracting high-value bioactive substances. By the adoption of the technical scheme, the problem that resource utilization of the sugarcane leaves cannot be achieved in the prior art is solved, comprehensive utilization of the sugarcane leaves is achieved, and therefore the benefits of sugarcane planting are indirectly increased.

Description

Technical Field

[0001] The invention relates to the field of resource utilization, and in particular to a method for comprehensive utilization of sugarcane leaves. Background Art

[0002] Sugarcane leaves are the main by-product of sugarcane harvest, with an annual global production of over 300 million tons. Their efficient recycling is of great significance to the sustainable development of agriculture and environmental protection. However, existing technologies have significant defects: First, traditional open-air burning causes serious environmental pollution. The burning process releases a large amount of harmful substances such as PM2.5, CO2 and polycyclic aromatic hydrocarbons. Studies have shown that burning each ton of sugarcane leaves can produce 1.5-2.8kg of PM2.5 and cause the loss rate of soil organic matter to reach more than 40%, exacerbating farmland degradation. In addition, although direct return to the field can retain some nutrients, the cover layer of uncomposted sugarcane leaves (thickness > 15cm) will hinder the emergence of perennial sugarcane seedlings, and the high C / N ratio (> 80:1) will cause microorganisms to compete with crops for nitrogen, which in turn leads to a 12%-18% reduction in sugarcane yield.

[0003] Secondly, existing mechanized processing technology is inefficient and costly. Traditional crushing and returning equipment is limited by the entanglement characteristics of sugarcane leaf fibers (tensile strength > 200MPa), and the blade wear rate is as high as 0.5mm / h, so it needs to be replaced frequently, resulting in an increase of 80-120 yuan in operating costs per mu. At the same time, the length of sugarcane leaves after conventional crushing (> 10cm) is difficult to meet the needs of feed or composting and requires secondary processing, and the overall energy consumption has increased by more than 30%. For scattered planting areas, the centralized storage and transportation costs (> 150 yuan / ton) further weaken the economic feasibility, resulting in an abandonment rate of more than 60% by farmers.

[0004] Finally, the resource utilization pathway is single and the technology has poor adaptability. Existing technologies mostly focus on a single direction (such as fuel, feed or fertilizer) and fail to achieve multi-product synergy. For example, the direct combustion of sugarcane leaves for power generation has a large fluctuation in moisture content (45%-65%), a calorific value of only 8-10MJ / kg, and a boiler thermal efficiency of less than 50%; while feed production requires the addition of enzyme preparations (cost > 300 yuan / ton) to degrade lignin, but the crude protein content is still less than 6%, and the nutritional value is limited. In addition, the lack of graded processing technology tailored to the characteristics of sugarcane leaves has resulted in an extraction rate of less than 20% for high-value components (such as hemicellulose and phenolic substances), resulting in serious waste of resources. Summary of the Invention

[0005] The present invention aims to provide a method for comprehensive utilization of sugarcane leaves, which solves the problem that the existing technology cannot realize resource utilization of sugarcane leaves.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows: A method for comprehensive utilization of sugarcane leaves, comprising the following steps:

[0007] S1. Subjecting sugarcane leaves to fiber-oriented dissociation and microbial composite treatment to control fiber length to ≤5 cm and lignin degradation rate to ≥30%;

[0008] S2. Based on the differences in fiber length and chemical composition, the pretreated sugarcane leaves were separated into short fiber fraction, medium and long fiber fraction, and soluble fraction;

[0009] S3. The short fiber components are used to prepare slow-release organic fertilizers, the medium and long fiber components are used for feed processing, and the soluble components are used to extract high-value bioactive substances.

[0010] Furthermore, in step S1, the fiber directional dissociation adopts multi-stage differential shear pulverization, and the pulverized particle size distribution is controlled to be 0.5-5 cm, and the aspect ratio is ≤3:1.

[0011] Through this setup, differential shearing reduces tensile stress concentration in the fibers, and aspect ratio control prevents fibers from wrapping around the cutter. This reduces blade wear to less than 0.1 mm / h, reducing operating costs by 50%.

[0012] Furthermore, the speed gradient of the multi-stage differential shearing and crushing is 200-800 rpm, and the speed difference ratio of adjacent knife rollers is ≥1:2.5.

[0013] Through the above setting, the rotation speed gradient generates a synergistic effect of shear force and kneading force, avoiding excessive crushing, reducing the energy consumption of fiber dissociation by 35%, and the particle size qualification rate is greater than 98%.

[0014] Furthermore, the microbial composite treatment uses a compound bacterial agent of white rot fungi and nitrogen-fixing bacteria, the amount of the bacterial agent added is 1.5-2.5% of the dry weight of the sugarcane leaves, the treatment temperature is 35-45° C., and the humidity is 60-80%.

[0015] Through the above settings, white rot fungi secrete laccase to degrade lignin, and nitrogen-fixing bacteria make up for the nitrogen loss during the fermentation process, synergistically adjusting the C / N ratio. The lignin degradation rate is increased to more than 40%, and the nitrogen fixation amount reaches 0.8-1.2kg / ton of sugarcane leaves.

[0016] Furthermore, when the short fiber component is used to prepare the slow-release organic fertilizer, magnesium ammonium phosphate coating material is added, the coating thickness is 50-100 μm, and the coating rate is ≥95%.

[0017] Through the above settings, the coating material controls the nutrient release rate, avoids the concentrated nitrogen consumption by microorganisms, and improves the utilization rate of phosphorus and potassium. This reduces the soil organic matter loss rate to below 10%, and increases sugarcane yield by 15%-20%.

[0018] Furthermore, the ratio of N-P2O5-K2O-MgO in the ammonium magnesium phosphate coating material is 12:18:5:3, and humic acid is added to chelate trace elements.

[0019] Through the above settings, magnesium promotes chlorophyll synthesis, and humic acid chelation reduces nutrient fixation, so that the perennial sugarcane emergence rate is increased to more than 95%, and the fertilizer slow-release period reaches 120 days.

[0020] Furthermore, the medium and long fiber component feed processing adopts steam explosion combined with composite enzymatic hydrolysis, the explosion pressure is 1.5-2.0 MPa, and xylanase and cellulase are added to the enzymatic hydrolysis, and the enzyme activity ratio is 2:1.

[0021] Through the above settings, steam explosion destroys the crystallinity of the fiber, and complex enzymatic decomposition releases soluble sugars and protein precursors, thereby increasing the crude protein content to 12%-15% and the feed digestibility by more than 40%.

[0022] Furthermore, when extracting the bioactive substances from the soluble components, subcritical water extraction combined with molecular distillation is adopted, with an extraction temperature of 120-150° C. and a pressure of 5-8 MPa.

[0023] Through the above settings, subcritical water selectively dissolves hemicellulose, and molecular distillation separates heat-sensitive phenolic substances, resulting in a hemicellulose extraction rate of 85% and a phenolic substance purity of ≥90%.

[0024] Furthermore, the method further includes step S4, adding new sugarcane leaves produced after returning the organic fertilizer to the field back to the pretreatment stage at a mass ratio of 10%-15% as a microbial carrier.

[0025] Through the above arrangement, the indigenous bacterial flora carried by the added sugarcane leaves accelerates the degradation of lignin, forming a positive feedback loop, thereby increasing the microbial activity by 30% and shortening the processing time of step S1 by 20%.

[0026] Compared with the existing technology, this solution has the following beneficial effects:

[0027] 1. This program provides a method for the comprehensive utilization of sugarcane leaves. Through fiber directional dissociation and microbial composite treatment, it completely replaces traditional open-air burning, reducing PM2.5 emissions to below 0.1kg / ton (traditional incineration is 1.5-2.8kg / ton), while avoiding soil organic matter loss (the loss rate is reduced from 40% to below 10%). The slow-release organic fertilizer coating technology reduces nitrogen volatilization and reduces greenhouse gas emissions from farmland by more than 30%.

[0028] 2. This solution utilizes multi-stage differential shearing and pulverizing technology, reducing blade wear from 0.5mm / h to below 0.1mm / h, and operating costs by 50% (from the traditional 80-120 yuan per mu to 40-60 yuan). Furthermore, the tiered resource utilization (fertilizer, feed, and bioactive substances) increases overall returns by 2-3 times, increasing the value of each ton of sugarcane leaves from the negative return of traditional incineration (-150 yuan / ton) to a positive return of 500-800 yuan / ton.

[0029] 3. This solution increases the lignin degradation rate from 15% in traditional composting to over 40%, optimizing the C / N ratio from 80:1 to 25-30:1, eliminating competition for nitrogen between microorganisms and crops. Furthermore, the hemicellulose extraction rate increases from 20% to 85%, and the purity of phenolic compounds reaches ≥90%, enabling the cascade utilization of high-value components.

[0030] 4. This solution uses steam explosion combined with enzymatic hydrolysis to increase feed crude protein content from 6% to 12%-15%, meeting the nutritional needs of ruminants. Furthermore, slow-release organic fertilizer coating technology increases sugarcane emergence from 70% with traditional field return to 95%, increasing yield by 15%-20%. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below through specific embodiments:

[0032] Example

[0033] A method for comprehensive utilization of sugarcane leaves comprises the following steps:

[0034] S1. Sugarcane leaves are subjected to fiber dissociation and microbial composite treatment, with fiber length controlled to ≤5cm and lignin degradation rate ≥30%. Fiber dissociation utilizes multi-stage differential shear pulverization, with a controlled particle size distribution of 0.5-5cm and an aspect ratio ≤3:1. The multi-stage differential shear pulverization speed gradient ranges from 200-800rpm, with a speed differential ratio of ≥1:2.5 between adjacent blade rollers. Microbial composite treatment utilizes a combination of white rot fungi and nitrogen-fixing bacteria at a dosage of 1.5-2.5% of the sugarcane leaf dry weight. The treatment temperature is 35-45°C, and the humidity is 60-80%.

[0035] S2. Based on the differences in fiber length and chemical composition, the pretreated sugarcane leaves were divided into short fiber components (<2 cm), medium and long fiber components (2-5 cm) and soluble components.

[0036] S3. The short fiber component is used to prepare slow-release organic fertilizer, the medium and long fiber component is used for feed processing, and the soluble component is used to extract high-value bioactive substances. When preparing slow-release organic fertilizer from the short fiber component, an ammonium magnesium phosphate coating material is added with a coating thickness of 50-100 μm and a coating rate of ≥95%. The ratio of N-P2O5-K2O-MgO in the ammonium magnesium phosphate coating material is 12:18:5:3, and humic acid is added to chelate trace elements. The medium and long fiber component is processed into feed using steam explosion combined with composite enzymatic hydrolysis at a blasting pressure of 1.5-2.0 MPa. Xylanase and cellulase are added for enzymatic hydrolysis with an enzyme activity ratio of 2:1.

[0037] When extracting bioactive substances from soluble components, subcritical water extraction combined with molecular distillation is used, with an extraction temperature of 120-150°C and a pressure of 5-8MPa.

[0038] Step S4: adding the new sugarcane leaves produced after returning the organic fertilizer to the field back to the pretreatment stage at a mass ratio of 10%-15% as a microbial carrier.

[0039] Application Example 1

[0040] S1. Fiber directional dissociation and microbial composite treatment

[0041] A four-stage differential shear mill was used, with the blade roller speed gradient set at 400 rpm (first stage), 600 rpm (second stage), 800 rpm (third stage), and 1000 rpm (fourth stage). The speed differential ratio between adjacent blade rollers was 1:3 (400 rpm from first to second stage, 200 rpm from second to third stage, and 200 rpm from third to fourth stage). The fiber length after pulverization was measured to be 3.2 cm, with an aspect ratio of 2.1:1, and a particle size distribution concentrated in the range of 1.5-4.5 cm.

[0042] The microbial treatment used a combination of white-rot fungi (Pleurotus ostreatus) and nitrogen-fixing bacteria (Azotobacter vinelandii), added at a dosage of 2.0% of the sugarcane leaf dry weight. The treatment temperature was 40°C, the humidity was 70%, and the leaves were stored for 21 days. After treatment, infrared spectroscopy revealed a lignin degradation rate of 38.6%, and a cellulose retention rate of 82.3%.

[0043] S2. Component classification

[0044] Through the vibration screening and wind sorting system, the pre-treated materials are divided into:

[0045] Short fiber component (≤1.0cm, accounting for 35%)

[0046] Medium-long fiber component (1.0-5.0cm, accounting for 48%)

[0047] Soluble components (water-soluble substances and small molecule degradation products, accounting for 17%)

[0048] S3, multi-channel utilization

[0049] Preparation of slow-release organic fertilizer: The short fiber component is mixed with magnesium ammonium phosphate coating material (N-P2O5-K2O-MgO = 12:18:5:3) in a mass ratio of 8:2. The coating thickness is controlled at 75μm, with a coverage rate of 98.2%. The finished product has a total nutrient content (N+P2O5+K2O) of ≥6.5%, an organic matter content of 48.7%, and a slow-release period of up to 120 days.

[0050] Feed processing: After the medium and long fiber components were steam exploded (pressure 1.8 MPa, holding time 5 min), they were added with xylanase (3000 U / g) and cellulase (1500 U / g) for complex enzymatic hydrolysis. The crude protein content of the product increased to 16.8%, and the in vitro digestibility of dry matter was 72.4%.

[0051] Extraction of bioactive substances: The soluble components were extracted using subcritical water (temperature 135°C, pressure 6 MPa) combined with molecular distillation (distillation temperature 85°C, vacuum degree 0.1 Pa). The total flavonoid content in the extract reached 8.2 mg / g and the chlorogenic acid purity was 3.1%.

[0052] S4, loop back

[0053] After returning organic fertilizer to the fields, new sugarcane leaves were harvested, and 12% by weight of organic fertilizer was added back to the pretreatment stage. After secondary treatment with a microbial inoculant, the lignin degradation rate increased by 5.3 percentage points, demonstrating that the addition system enhanced the microbial carrier function.

[0054] Implementation effect:

[0055] The utilization rate of sugarcane leaves in the entire process reaches 96.7% (the utilization rate of traditional incineration method is <5%);

[0056] The economic benefits per unit mass of sugarcane leaves are 4.2 times higher than those from traditional treatments;

[0057] The annual growth rate of soil organic matter content reached 0.35% (0.12% in the control group).

[0058] Application Example 2

[0059] The only difference between this application example and application example 1 is:

[0060] S1: Three-stage differential shear pulverization (speed gradient 200-400-600 rpm), with a differential speed ratio of 1:2.5 (200 rpm difference from first to second stage, 200 rpm difference from second to third stage). Pulverization energy consumption was reduced by 38%, fiber length was 4.8 cm (close to the upper limit), and lignin degradation rate was 31.2% (microbial treatment time extended to 28 days).

[0061] S3. Feed processing uses low-temperature steam explosion (1.5MPa, pressure maintenance 8min), with a crude protein content of 15.1%, but energy consumption is reduced by 19%.

[0062] The extraction of bioactive substances was changed to ultrasonic-assisted extraction (power 200W, temperature 60°C), with a total flavonoid content of 7.6 mg / g and a 45% reduction in equipment investment.

[0063] Implementation effect:

[0064] The total cost is reduced by 22%, but the slow-release period of organic fertilizer is shortened to 90 days;

[0065] The in vitro digestibility of feed decreased to 68.7%;

[0066] Suitable for small-scale distributed processing scenarios.

[0067] Application Example 3

[0068] The only difference between this application example and application example 1 is:

[0069] S1: Five-stage differential shearing (speed gradient 200-400-600-800-1000 rpm), with a speed differential ratio of 1:3 (200 rpm difference from the first to the second stage, 200 rpm difference for each subsequent stage). The fiber length after crushing was 2.1 cm, and the lignin degradation rate was 45.8% (extended treatment to 35 days).

[0070] S3. Nano-silicon dioxide (0.5% by mass) is added to the organic fertilizer coating material, the coating thickness is 50 μm, and the nutrient release curve is smoother (sustained release period is 150 days).

[0071] The feed processing adopts two steam explosions (the first one is 1.8MPa and the second one is 1.2MPa), which increases the crude protein content to 18.3%, but the energy consumption increases by 33%.

[0072] The bioactive substances were extracted using supercritical CO2 fluid extraction (pressure 25 MPa, temperature 40°C), with a total flavonoid content of 12.7 mg / g and a chlorogenic acid purity of 5.8%. The equipment investment increased by 60%.

[0073] Implementation effect:

[0074] The revenue share of high value-added products reached 65% (42% in the control group);

[0075] Net profit per unit mass of sugarcane leaves increased by 89%;

[0076] Suitable for intensive processing bases.

[0077] Comparative Example

[0078] Processing flow:

[0079] Directly crush to a length of ≤10 cm (without fiber directional dissociation);

[0080] No microbial composite treatment was performed (only urea was added to adjust the C / N ratio);

[0081] The whole amount is mixed and fermented to prepare organic fertilizer (unclassified).

[0082] Parameter settings:

[0083] The mill speed was 1200 rpm (single-stage pulverization), with a fiber length distribution of 3-12 cm and a lignin degradation rate of only 8.9%. The uncoated organic fertilizer had a total nutrient content of 4.2%, an organic matter content of 38.5%, and a sustained-release period of 30 days. The feed processing, without steam explosion or enzymatic hydrolysis, had a crude protein content of 9.7% and an in vitro digestibility of 52.3%.

[0084] Implementation effect:

[0085] The utilization rate of sugarcane leaves is 78% (due to the long fibers being difficult to decompose);

[0086] Soil bulk density increased by 12% (compared to a decrease of 8% in control application example 1);

[0087] Poor feed palatability leads to a 28% decrease in livestock feed intake;

[0088] The economic benefit per unit mass of sugarcane leaves is only 37% of that in Application Example 1.

[0089] Data Analysis:

[0090] 1. Precise control of multi-stage differential shearing technology

[0091] Application Example 1 utilizes a four-stage speed gradient (400-1000 rpm) and a 1:3 speed differential ratio to achieve a fiber length of 3.2 cm (±0.5 cm deviation) while controlling energy consumption. This is significantly shorter than the 12 cm achieved with the single-stage pulverization in the control example, effectively improving the efficiency of subsequent microbial degradation. Experiments have shown that when fiber length is reduced from 12 cm to 3 cm, the exposed area of ​​lignin increases by 4.2 times, and the degradation rate increases by 3.8 times.

[0092] 2. Synergistic effect of microbial complex system

[0093] When treated at 40°C and 70% humidity, the white-rot fungus-nitrogen-fixing bacteria combination increased lignin peroxidase (LiP) and manganese peroxidase (MnP) activities by 58% compared to single-bacteria treatments, and nitrogenase activity by 35%. The 38.6% degradation rate in Application Example 1 was 3.0 times higher than that of the control, and nitrogen fixation increased the total nitrogen content of the compost by 19.7%.

[0094] 3. Value gradient development of component graded utilization

[0095] The three-level utilization system achieved through wind separation maximizes the value of each component:

[0096] Short fibers (≤1.0 cm) are used as organic fertilizer carriers. The nutrient release curve after coating is 89% consistent with the sugarcane growth period requirements.

[0097] After steam explosion of medium-long fibers (1.0-5.0 cm), the hemicellulose conversion rate increased from 42% to 78%, significantly enhancing the palatability of the feed.

[0098] The purity of flavonoids extracted from the soluble components reaches pharmaceutical grade standards (≥80%), which is 6.3 times higher than that of the traditional water boiling method.

[0099] 4. Ecological strengthening of the recycling system

[0100] In Application Example 1, a 12% backfill ratio increased the pretreatment microbial biomass by 35% and the activity of the key lignin-degrading enzyme (LiP) by 28%. After three generations of recycling, the pile heating rate increased by 1.7 times, and the time to enter the high-temperature degradation stage (≥55°C) was shortened by 40%, forming an autocatalytic effect.

[0101] 5. Economic balance of process parameters

[0102] In Application Example 2, by reducing the rotation speed gradient to 200-600 rpm, the lignin degradation rate dropped to 31.2%, but the unit energy cost was reduced by 0.42 yuan / kg, making it suitable for small-scale farmers with a processing scale of less than 50 tons / day. In Application Example 3, by strengthening the shearing and extraction conditions, although the equipment investment increased by 60%, the high-value-added product benefits shortened the payback period to 2.8 years.

[0103] The above are only embodiments of the present invention, and common knowledge such as the specific structure and / or characteristics of the scheme are not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for comprehensive utilization of sugarcane leaves, characterized in that: The steps include: S1. Subjecting sugarcane leaves to fiber-oriented dissociation and microbial composite treatment to control fiber length to ≤5 cm and lignin degradation rate to ≥30%; S2. Based on the differences in fiber length and chemical composition, the pretreated sugarcane leaves were separated into short fiber fraction, medium and long fiber fraction, and soluble fraction; S3. The short fiber components are used to prepare slow-release organic fertilizers, the medium and long fiber components are used for feed processing, and the soluble components are used to extract high-value bioactive substances.

2. The method for comprehensive utilization of sugarcane leaves according to claim 1, characterized in that: In step S1, the fiber is oriented and dissociated by multi-stage differential shearing and pulverizing, and the pulverized particle size distribution is controlled to be 0.5-5 cm, and the aspect ratio is ≤3:

1.

3. The method for comprehensive utilization of sugarcane leaves according to claim 2, characterized in that: The rotation speed gradient of the multi-stage differential shearing and crushing is 200-800 rpm, and the speed difference ratio of adjacent knife rollers is ≥1:2.

5.

4. The method for comprehensive utilization of sugarcane leaves according to claim 1, characterized in that: The microbial composite treatment uses a compound bacterial agent of white rot fungi and nitrogen-fixing bacteria, the amount of the bacterial agent added is 1.5-2.5% of the dry weight of the sugarcane leaves, the treatment temperature is 35-45° C., and the humidity is 60-80%.

5. The method for comprehensive utilization of sugarcane leaves according to claim 1, characterized in that: When the short fiber component is used to prepare the slow-release organic fertilizer, magnesium ammonium phosphate coating material is added, the coating thickness is 50-100 μm, and the coating rate is ≥95%.

6. The method for comprehensive utilization of sugarcane leaves according to claim 5, characterized in that: The ratio of N-P2O5-K2O-MgO in the ammonium magnesium phosphate coating material is 12:18:5:3, and humic acid is added to chelate trace elements.

7. The method for comprehensive utilization of sugarcane leaves according to claim 1, characterized in that: The medium and long fiber component feed processing adopts steam explosion combined with composite enzymatic hydrolysis, the explosion pressure is 1.5-2.0 MPa, and xylanase and cellulase are added in the enzymatic hydrolysis, and the enzyme activity ratio is 2:

1.

8. The method for comprehensive utilization of sugarcane leaves according to claim 1, characterized in that: When the bioactive substances are extracted from the soluble components, subcritical water extraction combined with molecular distillation is adopted, the extraction temperature is 120-150° C., and the pressure is 5-8 MPa.

9. The method for comprehensive utilization of sugarcane leaves according to claim 1, characterized in that: The method further includes step S4, adding new sugarcane leaves produced after returning the organic fertilizer to the field back to the pretreatment stage at a mass ratio of 10%-15% as a microbial carrier.