A method for reusing a by-product of pyrethrin refining

Abstract

The present application belongs to the technical field of insecticide by-products, and provides a method for recycling by-products of pyrethrum ester refining products. The recycling method comprises the following steps: (1) collecting by-products; (2) detoxification treatment: the by-products are treated with high-temperature steam and then cooled to obtain pretreated residues; the pretreated residues are mixed with an ethanol aqueous solution and then ultrasonically extracted; after the extraction is completed, the solid-liquid centrifugal separation is performed to obtain preliminarily detoxified residues; the preliminarily detoxified residues are mixed with a solution of complex enzymes and then enzymolyzed, followed by filtration to obtain deeply detoxified residues; (3) drying treatment: the deeply detoxified residues are dried to obtain pretreated residues; and (4) biomass particle preparation: the pretreated residues are granulated after being added with auxiliary materials, and then cooled and sieved to obtain biomass particles. The recycling method can convert the biomass components in the solid residues generated after the pyrethrum ester refining into biomass energy, which can not only solve the problem of by-product treatment and reduce environmental pollution, but also realize resource recycling and create economic value.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of insecticide by-product processing, in particular, relates to a method for recycling by-products of pyrethrum ester refined products. BACKGROUND

[0002] Pyrethrum ester is a light yellow oily liquid extracted from pyrethrum flowers, which is recognized as an ideal natural insecticide in the world. It has good contact killing effect on many pests, and has little toxicity to humans and warm-blooded animals, and is quickly decomposed in the natural environment without residue and resistance. Due to the characteristics of quick-acting, low toxicity, low resistance, broad-spectrum and repellent, pyrethrum ester is widely used in environmental health and pest control and repellent in agriculture and forestry.

[0003] Domestic and foreign production of pyrethrum ester basically adopts organic solvent extraction, supercritical CO2 extraction and subcritical fluid extraction and other methods. The pyrethrum ester produced by these methods is an oil resin, which contains a large amount of wax, pigment, resinous colloidal substance and free fatty acid, which seriously affects the quality of pyrethrum ester and restricts its application. Pyrethrum ester must be refined as a product.

[0004] In the production process of pyrethrum ester refined products, a certain amount of by-products will be produced. If these by-products are not utilized and directly discharged, on the one hand, it will cause great waste of resources, because the by-products may contain some chemical components with potential value; on the other hand, random discharge will also cause serious pollution to the environment and increase the cost of environmental governance.

[0005] At present, the treatment technology of pyrethrum ester refined product by-products is limited. The traditional treatment method is simple incineration or landfill. The incineration process not only may produce harmful gases such as chlorine-containing and other toxic and harmful components, which will pollute the atmospheric environment, but also wastes the potential resources contained in the by-products. Landfill treatment may cause harmful substances in the by-products to seep into the soil and groundwater, causing long-term accumulation and damage to the soil and water ecology, and occupying a large amount of valuable land resources. Some enterprises try to preliminarily separate the by-products, but due to the limitation of technical means, the separation effect is not good, and the economically valuable components cannot be effectively extracted, the treatment cost is high and the efficiency is low, and it is difficult to realize large-scale industrialized application.

[0006] Therefore, it is of social and economic significance to develop an efficient, environmentally friendly and economically feasible pyrethrum ester refined product by-product processing method. SUMMARY

[0007] In view of the above deficiencies in the prior art, the present application aims to provide a method for recycling by-products of pyrethrum ester refined products. The recycling method can convert the biomass components in the solid residues generated after pyrethrum ester refining into biomass energy, which can not only solve the problem of by-product disposal and reduce environmental pollution, but also realize resource recycling and create economic value.

[0008] To achieve the above-mentioned purpose, the present application adopts the following solution:

[0009] A method for recycling by-products of pyrethrum ester refined products, comprising: (1) collecting by-products: collecting the solid residues after pyrethrum ester refining, removing foreign matter, and crushing the solid residues to obtain crushed residues; (2) detoxification treatment: placing the crushed residues in a high-temperature steam treatment machine, treating at a temperature of 120-150 DEG C, a steam pressure of 0.15-0.3 MPa, and high-temperature steam for 30-40 min, and then cooling to obtain pretreated residues; mixing the pretreated residues with an ethanol aqueous solution with a volume fraction of 60-70%, and then ultrasonic extraction; after the extraction is completed, centrifugal separation of solid-liquid is performed to obtain preliminary detoxification residues; mixing the preliminary detoxification residues with a solution of a composite enzyme, and then enzymolysis, followed by filtration to obtain deep detoxification residues; the composite enzyme comprises cellulase, ligninase and pyrethrum ester degrading enzyme in a mass ratio of 1:1:1; (3) drying treatment: drying the deep detoxification residues to obtain pretreated residues; (4) biomass pellet preparation: adding auxiliary materials to the pretreated residues, and then extruding and granulating, and then cooling and sieving to obtain biomass pellets.

[0010] Further, in the preferred embodiment of the present application, in step (2), the conditions for ultrasonic extraction include: the solid-liquid ratio of pretreated residues to ethanol aqueous solution is 1:4-6, the ultrasonic frequency is 20-40 kHz, the ultrasonic power density is 0.2-0.5 W / cm 2 , the extraction temperature is 30-40 DEG C, and the extraction time is 20-30 min.

[0011] Further, in the preferred embodiment of the present application, in step (2), the conditions for centrifugal separation include: the rotation speed is 3000-4000 r / min, and the time is 10-15 min.

[0012] Further, in the preferred embodiment of the present application, in step (2), the conditions for enzymolysis include: the addition amount of the composite enzyme is 0.5-1.0% of the mass of the preliminary detoxification residues, the enzymolysis temperature is 40-50 DEG C, the pH value is 5.5-6.5, and the enzymolysis time is 4-6 h.

[0013] Further, in the preferred embodiment of the present application, in step (3), the deep detoxification residues are first subjected to low-temperature vacuum drying, and then subjected to hot air drying.

[0014] Further, in the preferred embodiment of the present application, the conditions of the low-temperature vacuum drying include: vacuum degree of -0.08 to -0.10 MPa, drying temperature of 40 to 50 DEG C, and drying time of 1 to 2 hours.

[0015] Further, in the preferred embodiment of the present application, the conditions of the hot air drying include: temperature of 80 to 100 DEG C, and drying time of 30 to 60 minutes.

[0016] Further, in the preferred embodiment of the present application, in step (4), the preparation of the biomass particles includes: adding 2 to 5% of starch to the pretreated residues, spraying water after mixing to obtain a mixture, and the moisture content of the mixture is 12 to 15%; the mixture is sent into a ring die pelletizer to perform extrusion granulation under the conditions of a rotation speed of 80 to 120 r / min and a pressure of 5 to 8 MPa of the compression roller; then, the cooled particles are cooled by a countercurrent cooler, the cooling medium is normal temperature air, and the cooling time is 10 to 15 minutes; and the cooled particles are screened by a vibrating screen to obtain the biomass particles.

[0017] The method for recycling the by-products of the pyrethrum ester refined product has the following beneficial effects:

[0018] (1) The solid residues after the pyrethrum ester refining mainly include cellulose, hemicellulose, lignin, a small amount of residual pyrethrum ester, and other organic impurities. Among them, the cellulose and the hemicellulose are main components for conversion into biomass energy; the residual pyrethrum ester needs to be completely removed in the treatment process to avoid affecting the subsequent energy production and application.

[0019] The method for recycling the by-products of the pyrethrum ester refined product can completely remove the residual pyrethrum ester, and convert the cellulose, hemicellulose, lignin and other by-products into biomass energy, which can solve the problem of by-product treatment, reduce environmental pollution, realize resource recycling, create economic value, and realize the reduction, harmlessness and resource of the pyrethrum ester by-products, while taking into account the environmental and economic benefits.

[0020] (2) The method for recycling the by-products of the pyrethrum ester refined product first performs a mild high-temperature steam treatment, then adopts specific organic solvent chemical ultrasonic extraction, and then adopts enzymatic treatment in the detoxification treatment step.

[0021] The above processing mode utilizes the heat effect of steam to heat and destroy part of the toxin structure, and at the same time, softens the material organization, increases the permeability and opens the pores, which is beneficial to the subsequent chemical reagent to penetrate into the material interior more quickly and more fully, combine with the toxin and extract it out; the cavitation effect and mechanical effect generated by the ultrasonic can accelerate the dissolution of the residual pyrethroid and other toxic and harmful substances from the residue, improve the extraction efficiency and ensure that the removal rate of the residual pyrethroid reaches more than 99%; the biological enzyme can specifically decompose the residual pyrethroid and other organic impurities, and further reduce the content of toxic substances in the residue.

[0022] The steps are cooperated with each other, so that the residual pyrethroid and other toxic and harmful substances in the residue are completely removed.

[0023] (3) The by-product recycling method of the pyrethroid refined product provided by the application adopts a multi-stage drying system: low-temperature vacuum drying is first adopted, and then hot air drying is adopted; the low-temperature vacuum drying can quickly remove water at a lower temperature, avoids the damage of high temperature to the effective components in the residue, reduces the energy consumption at the same time, the hot air drying further reduces the water content of the residue to meet the requirements of subsequent extrusion granulation. The two are cooperated with each other, which not only reduces the energy consumption, but also retains the effective components and improves the drying efficiency, and also reduces the energy consumption. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the application more clear, the technical scheme in the embodiments of the application will be clearly and completely described below. The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be purchased in the market.

[0025] The features and performances of the application will be further described below in combination with the embodiments.

[0026] Embodiment 1

[0027] (1) By-product collection: collect the solid residue after pyrethroid extraction, remove stones, metals and other foreign matters, crush the solid residue to obtain crushed slag with a particle size of less than 5 mm;

[0028] (2) Detoxification treatment: place the crushed slag in a high-temperature steam treatment machine, cool after high-temperature steam treatment at a temperature of 135 DEG C and a steam pressure of 0.18 MPa for 35 min, to obtain pretreated crushed slag; mix the pretreated crushed slag with an ethanol aqueous solution with a volume fraction of 65% according to a solid-liquid ratio of 1:5, and then ultrasonic treatment is carried out at an ultrasonic frequency of 30 kHz and an ultrasonic power density of 0.4 W / cm 2, the extraction temperature is 35℃, and the extraction lasts for 25 minutes; after the extraction, the solid-liquid centrifugal separation is performed at a rotation speed of 3500 r / min for 13 minutes to obtain the preliminary detoxification residue; the preliminary detoxification residue is mixed with the solution of the complex enzyme, and then enzymolysis is performed at an enzymolysis temperature of 45℃ and a pH value of 6.0 for 5 hours, followed by filtration to obtain the deep detoxification residue; the complex enzyme includes cellulase, ligninase and pyrethrin-degrading enzyme in a mass ratio of 1:1:1; the addition amount of the complex enzyme is 0.8% of the mass of the preliminary detoxification residue;

[0029] (3) drying treatment: the deep detoxification residue is dried at a temperature of 90℃ for 60 minutes by hot air to obtain the pretreated residue;

[0030] (4) biomass pellet preparation: 3% of starch is added to the pretreated residue, and then water is sprayed to obtain a mixture; the water content of the mixture is 14%; the mixture is sent into a ring die pelletizer to perform extrusion granulation at a rotation speed of 100 r / min and a pressure roller pressure of 7 MPa; then, the cooled medium is normal temperature air, and the cooling lasts for 13 minutes; the cooled pellets are screened by a vibrating screen to obtain the biomass pellets.

[0031] Example 2

[0032] The embodiment provides a method for reusing a byproduct of a pyrethrin refined product, and the difference from the embodiment 1 is that:

[0033] (2) detoxification treatment: the crushed residue is placed in a high-temperature steam treatment machine, and then high-temperature steam treatment is performed at a temperature of 120℃ and a steam pressure of 0.3 MPa for 30 minutes, and then the pretreated crushed residue is obtained after cooling; the pretreated crushed residue is mixed with an ethanol aqueous solution with a volume fraction of 70% according to a solid-liquid ratio of 1:4, and then ultrasonic treatment is performed at an ultrasonic frequency of 40 kHz and an ultrasonic power density of 0.2 W / cm 2 , the extraction temperature is 40℃, and the extraction lasts for 20 minutes; after the extraction, the solid-liquid centrifugal separation is performed at a rotation speed of 4000 r / min for 10 minutes to obtain the preliminary detoxification residue; the preliminary detoxification residue is mixed with the solution of the complex enzyme, and then enzymolysis is performed at an enzymolysis temperature of 50℃ and a pH value of 5.5 for 6 hours, followed by filtration to obtain the deep detoxification residue; the complex enzyme includes cellulase, ligninase and pyrethrin-degrading enzyme in a mass ratio of 1:1:1; the addition amount of the complex enzyme is 0.5% of the mass of the preliminary detoxification residue.

[0034] (4) Biomass pellet preparation: 5% starch was added to the pretreated residue, and the mixture was sprayed with water to obtain a mixture with a moisture content of 12%; the mixture was fed into a ring die pelletizer to perform extrusion granulation under the conditions of a rotation speed of 120 r / min and a pressure roller pressure of 5 MPa; then cooling was performed through a countercurrent cooler, the cooling medium was normal temperature air, and the cooling time was 15 min; the cooled pellets were screened through a vibrating screen to obtain biomass pellets.

[0035] Example 3

[0036] The present example provides a method for reusing the byproduct of pyrethrum ester refined product, which is different from example 1 in that:

[0037] (2) detoxification treatment: the crushed residue was placed in a high-temperature steam treatment machine, and after high-temperature steam treatment at a temperature of 150°C and a steam pressure of 0.15 MPa for 40 min, the crushed residue was cooled to obtain pretreated crushed residue; the pretreated crushed residue was mixed with an ethanol aqueous solution with a volume fraction of 60% according to a solid-liquid ratio of 1:6, and then ultrasonic treatment was performed at an ultrasonic frequency of 20 kHz and an ultrasonic power density of 0.5 W / cm 2 ; the extraction temperature was 30°C, and the extraction time was 30 min; after the extraction was completed, solid-liquid centrifugal separation was performed at a rotation speed of 3000 r / min for 15 min to obtain preliminary detoxification residue; the preliminary detoxification residue was mixed with a solution of a composite enzyme, and then enzymolysis was performed at an enzymolysis temperature of 40°C and a pH value of 6.5 for 4 h, followed by filtration to obtain deeply detoxified residue; the composite enzyme includes cellulase, ligninase and pyrethrum ester degrading enzyme in a mass ratio of 1:1:1; the addition amount of the composite enzyme is 1.0% of the mass of the preliminary detoxification residue.

[0038] (4) Biomass pellet preparation: 5% starch was added to the pretreated residue, and the mixture was sprayed with water to obtain a mixture with a moisture content of 12%; the mixture was fed into a ring die pelletizer to perform extrusion granulation under the conditions of a rotation speed of 120 r / min and a pressure roller pressure of 5 MPa; then cooling was performed through a countercurrent cooler, the cooling medium was normal temperature air, and the cooling time was 15 min; the cooled pellets were screened through a vibrating screen to obtain biomass pellets.

[0039] Example 4

[0040] The present example provides a method for reusing the byproduct of pyrethrum ester refined product, which is different from example 1 in that:

[0041] Example 5

[0042] The present example provides a method for reusing the byproduct of pyrethrum ester refined product, which is different from example 1 in that: (3) drying treatment: the deep detoxification residue is first subjected to low-temperature vacuum drying at a vacuum degree of-0.08 MPa and a drying temperature of 50°C for 1 h, and then subjected to hot air drying at a temperature of 80°C for 60 min to obtain a pretreated residue.

[0043] Example 6

[0044] The present example provides a method for reusing the byproduct of pyrethrum ester refined product, which is different from example 1 in that: (3) drying treatment: the deep detoxification residue is first subjected to low-temperature vacuum drying at a vacuum degree of-0.08 MPa and a drying temperature of 50°C for 1 h, and then subjected to hot air drying at a temperature of 80°C for 60 min to obtain a pretreated residue.

[0045] Comparative Example 1

[0046] The present comparative example provides a method for reusing the byproduct of pyrethrum ester refined product, which comprises:

[0047] (1) byproduct collection: collecting the solid residue after pyrethrum ester refining, removing stones, metals and other foreign matters, and crushing the solid residue to obtain crushed residue with a particle size of less than 5 mm;

[0048] (2) detoxification treatment: mixing the crushed residue with an ethanol aqueous solution with a volume fraction of 65% according to a solid-liquid ratio of 1:5, and then extracting at an ultrasonic frequency of 30 kHz, an ultrasonic power density of 0.4 W / cm 2 , an extraction temperature of 35°C and for 25 min; and centrifuging the solid-liquid mixture at a rotation speed of 3500 r / min for 13 min to obtain a detoxification residue;

[0049] (3) drying treatment: drying the detoxification residue at a temperature of 90°C for 60 min to obtain a pretreated residue;

[0050] (4) biomass pellet preparation: adding 3% of starch to the pretreated residue, mixing and then spraying water to obtain a mixture, wherein the water content of the mixture is 14%; feeding the mixture into a ring die pelletizer to perform extrusion granulation under the conditions of a rotation speed of 100 r / min and a roller pressure of 7 MPa; then cooling the mixture through a counterflow cooler, wherein the cooling medium is normal temperature air, and the cooling time is 13 min; and screening the cooled pellets through a vibrating screen to obtain biomass pellets.

[0051] Comparative Example 2

[0052] The comparative example provides a method for reusing the byproduct of pyrethrum ester refined product, which is different from example 1 in that: (2) detoxification treatment: the crushed slag is placed in a high-temperature steam treatment machine, treated at a temperature of 135 ℃ and a steam pressure of 0.18 MPa for 35 min, and then cooled to obtain pretreated crushed slag; the pretreated crushed slag is mixed with an ethanol aqueous solution with a volume fraction of 65% at a solid-liquid ratio of 1:5, and then extracted at an ultrasonic frequency of 30 kHz, an ultrasonic power density of 0.4 W / cm 2 , and an extraction temperature of 35 ℃ for 25 min; after the extraction is completed, the solid-liquid is centrifuged at a speed of 3500 r / min for 13 min to obtain detoxification residues.

[0053] Comparative example 3

[0054] The comparative example provides a method for reusing the byproduct of pyrethrum ester refined product, which is different from example 1 in that: (2) detoxification treatment: the crushed slag is mixed with an ethanol aqueous solution with a volume fraction of 65% at a solid-liquid ratio of 1:5, and then extracted at an ultrasonic frequency of 30 kHz, an ultrasonic power density of 0.4 W / cm 2 , and an extraction temperature of 35 ℃ for 25 min; after the extraction is completed, the solid-liquid is centrifuged at a speed of 3500 r / min for 13 min to obtain detoxification residues; the preliminary detoxification residues are mixed with a solution of a composite enzyme, and then enzymolysis is performed at an enzymolysis temperature of 45 ℃ and a pH value of 6.0 for 5 h, followed by filtration to obtain deep detoxification residues; the composite enzyme includes cellulase, ligninase, and pyrethrum ester-degrading enzyme at a mass ratio of 1:1:1; the addition amount of the composite enzyme is 0.8% of the mass of the preliminary detoxification residues.

[0055] Comparative example 4

[0056] The comparative example provides a method for reusing the byproduct of pyrethrum ester refined product, which is different from example 1 in that: (2) detoxification treatment: the crushed slag is placed in a high-temperature steam treatment machine, treated at a temperature of 100 ℃ and a steam pressure of 0.4 MPa for 60 min, and then cooled to obtain pretreated crushed slag; the pretreated crushed slag is mixed with an ethanol aqueous solution with a volume fraction of 75% at a solid-liquid ratio of 1:7, and then extracted at an ultrasonic frequency of 50 kHz, an ultrasonic power density of 0.1 W / cm 2 , and an extraction temperature of 25 ℃ for 40 min; after the extraction is completed, the solid-liquid is centrifuged at a speed of 2000 r / min for 20 min to obtain preliminary detoxification residues; the preliminary detoxification residues are mixed with a solution of a composite enzyme, and then enzymolysis is performed at an enzymolysis temperature of 35 ℃ and a pH value of 5 for 7 h, followed by filtration to obtain deep detoxification residues; the composite enzyme includes cellulase, ligninase, and pyrethrum ester-degrading enzyme at a mass ratio of 1:1:1; the addition amount of the composite enzyme is 0.2% of the mass of the preliminary detoxification residues.

[0057] Comparative example 5

[0058] The comparative example provides a method for reusing the byproduct of pyrethrum ester refining product, which is different from example 1 in that: (3) drying treatment: the deep detoxification residue is first subjected to low-temperature vacuum drying at a vacuum degree of -0.05 MPa and a drying temperature of 60°C for 3 h, and then subjected to hot air drying at a temperature of 110°C for 90 min to obtain a pretreated residue.

[0059] Experimental example 1

[0060] The residual pyrethrum ester concentration of the biomass particles provided in examples 1-6 and comparative examples 1-5 is detected:

[0061] (1) Sample pretreatment: extraction: weigh 5.0 g of the treated byproduct sample, add 50 mL of ethyl acetate, and oscillate on a shaker at 200 rpm for 30 min, repeat the extraction for 2 times, and combine the extraction liquid; purification: remove water from the extraction liquid by passing through anhydrous sodium sulfate column (5 g of anhydrous sodium sulfate), concentrate to near dryness by rotary evaporation, make up to 1.0 mL with n-hexane, pass through a 0.22 μm filter membrane, and wait for detection on the instrument.

[0062] (2) Gas chromatography-mass spectrometry instrument parameters: chromatographic column: DB-5MS capillary column (30 m x 0.25 mm x 0.25 μm); temperature rising program: initial temperature 60°C, hold for 1 min, rise to 200°C at 20°C / min, then rise to 280°C at 5°C / min, hold for 5 min; injection port temperature: 280°C, non-split injection, injection volume 1 μL; mass spectrometry conditions: electron impact source, ion source temperature 230°C, scan range 50-500 m / z, selected ion monitoring mode, monitoring pyrethrum ester characteristic ions.

[0063] (3) Quantitative method: external standard method: prepare 0.01, 0.1, 1, 10, and 50 μg / mL standard curves with pyrethrum ester standard (purity ≥ 99.5%), and plot the standard curve with peak area vs. concentration.

[0064] (4) The detection results are shown in Table 1:

[0065] Table 1

[0066]

[0067] The results in Table 1 show that the biomass particles obtained by the method for reusing the byproduct of pyrethrum ester refining product provided in examples 1-6 have a residual pyrethrum ester concentration significantly lower than the national standard limit (GB 2763-2021 National Food Safety Standard Maximum Residue Limits of Pesticides in Foods).

[0068] Experimental example 2

[0069] (1) Cellulose / hemicellulose degradation rate

[0070] Detection method: acid hydrolysis-high performance liquid chromatography (HPLC) method.

[0071] Operation: 2g of each sample of biomass particles provided by Examples 1-6 and Comparative Examples 1-5 was weighed, 20mL of 72% H2SO4 was added for hydrolysis at room temperature for 1h, diluted to 4% of sulfuric acid concentration, cooked at 121℃ for 1h, and the supernatant was taken after centrifugation.

[0072] Detection: HPLC (Agilent 1260) equipped with a refractive index detector (RID) to determine the content of glucose (cellulose hydrolysis product) and xylose (hemicellulose hydrolysis product).

[0073] Calculation: degradation rate (%) = (1 - total sugar content of raw material / residual sugar content) x 100%

[0074] (2) Lignin removal rate

[0075] Detection method: ultraviolet spectrophotometry (UV).

[0076] Operation: After acid hydrolysis of the biomass particle samples provided by Examples 1-6 and Comparative Examples 1-5, the residue was extracted with dioxane-sulfuric acid solution (volume ratio 9:1) by refluxing, the supernatant was taken after centrifugation, and the absorbance was measured at 205nm, and quantified according to the standard curve.

[0077] Calculation: removal rate (%) = (1 - lignin content of raw material / residual lignin content) x 100%

[0078] (3) Detection results: cellulose degradation rate (%), hemicellulose degradation rate (%) and lignin removal rate (%) are shown in Table 2:

[0079] Table 2

[0080] Group No. Cellulose degradation rate (%) Hemicellulose degradation rate (%) Lignin removal rate (%) Example 1 92％ 94％ 81％ Example 2 91％ 93％ 80％ Example 3 90％ 93％ 80％ Example 4 96％ 99％ 84％ Example 5 95％ 98％ 83％ Example 6 96％ 98％ 84％ Comparative Example 1 82％ 83％ 65％ Comparative Example 2 85％ 90％ 71％ Comparative Example 3 84％ 88％ 70％ Comparative Example 4 82％ 87％ 73％ Comparative Example 5 85％ 88％ 74％

[0081] The results in Table 2 show that the by-product reuse method of pyrethrum ester refined product provided by Examples 1-6 has excellent cellulose degradation rate, hemicellulose degradation rate and lignin removal rate, indicating that the efficiency of converting by-products into biomass energy is high, far exceeding the utilization rate of traditional single combustion or landfill.

[0082] In summary, the by-product reuse method of pyrethrum ester refined product provided by the present application can convert the biomass components in the solid residue after pyrethrum ester refining into biomass energy, which not only solves the problem of by-product disposal and reduces environmental pollution, but also realizes resource reuse and creates economic value.

[0083] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A method for reusing a by-product of pyrethrin refining, characterized by: The method comprises the following steps: (1) collecting the solid residues after the pyrethrum ester extraction, removing the foreign matters, and crushing the solid residues to obtain crushed residues; (2) placing the crushed residues in a high-temperature steam treatment machine, treating the crushed residues at a temperature of 120-150 DEG C and a steam pressure of 0.15-0.3 MPa for 30-40 min, and then cooling to obtain pretreated residues; mixing the pretreated residues with an ethanol aqueous solution with a volume fraction of 60-70%, and then ultrasonic extraction; after the extraction, centrifugal separation is performed to obtain primary detoxification residues; mixing the primary detoxification residues with a solution of a composite enzyme, and then enzymolysis, and then filtering to obtain deeply detoxified residues; the composite enzyme comprises cellulase, ligninase and pyrethrum ester-degrading enzyme at a mass ratio of 1:1:1; (3) drying the deeply detoxified residues to obtain pretreated residues; (4) adding auxiliary materials to the pretreated residues, and then extruding and granulating to obtain the biomass granules.

2. The method according to claim 1, wherein: In step (2), the conditions of ultrasonic extraction include: the solid-liquid ratio of the pretreated slag and the aqueous ethanol solution is 1:4-6, the ultrasonic frequency is 20-40 kHz, the ultrasonic power density is 0.2-0.5 W / cm 2 , the extraction temperature is 30-40℃, and the extraction time is 20-30 min. In step (2), the conditions of ultrasonic extraction include: the solid-liquid ratio of the pretreated slag and the aqueous ethanol solution is 1:4-6, the ultrasonic frequency is 20-40 kHz, the ultrasonic power density is 0.2-0.5 W / cm 2 , the extraction temperature is 30-40℃, and the extraction time is 20-30 min.

3. The method of claim 1, wherein the by-product is a by-product of a process for refining pyrethrin esters. In step (2), the centrifugal separation is performed at a rotation speed of 3000-4000 r / min for 10-15 min.

4. The method of claim 1, wherein the by-product is a by-product of a process for refining pyrethrin esters. In step (2), the enzymolysis is performed at an enzyme addition amount of 0.5-1.0% of the mass of the primary detoxification residues, an enzymolysis temperature of 40-50 DEG C, a pH value of 5.5-6.5, and an enzymolysis time of 4-6 h.

5. The method of claim 1, wherein the by-product of the pyrethrin refining is a distillate. In step (3), the deeply detoxified residues are first subjected to low-temperature vacuum drying, and then subjected to hot-air drying.

6. The method according to claim 5, wherein: The low-temperature vacuum drying is performed at a vacuum degree of-0.08 to-0.10 MPa and a drying temperature of 40-50 DEG C for 1-2 h.

7. The method according to claim 5, wherein: The hot-air drying is performed at a temperature of 80-100 DEG C for 30-60 min.

8. The method of claim 1, wherein the by-product is a by-product of a pyrethrin refining process. In step (4), the biomass granule preparation comprises the following steps: adding 2-5% of starch to the pretreated residues, mixing, and then spraying water to obtain a mixture, wherein the water content of the mixture is 12-15%; feeding the mixture into a ring die granulator to perform extrusion granulation at a rotation speed of 80-120 r / min and a pressure roller pressure of 5-8 MPa; then cooling through a counterflow cooler, wherein the cooling medium is normal-temperature air, and the cooling time is 10-15 min; and then screening the cooled granules through a vibrating screen to obtain the biomass granules.

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