A method for full resource utilization of kitchen waste

Abstract

The application provides a kitchen waste full-amount resource utilization method, and belongs to the technical field of waste resource utilization, which comprises the following steps: three-phase separation of kitchen waste to obtain kitchen solid residue, kitchen wastewater and swill oil; resource utilization of the swill oil; biological conversion of the kitchen solid residue and the kitchen wastewater by black soldier fly; and preparation of animal liquid feed by fermentation of the kitchen wastewater, so that full-amount resource utilization of kitchen waste is realized. In addition, the kitchen wastewater is further used as a nutrition regulator and a moisture regulator for the breeding and development of black soldier fly, so that black soldier fly with high content of nutritional ingredients and high-quality worm sand organic fertilizer raw materials are obtained; the black soldier fly and the kitchen wastewater produced by biological conversion are used as a nitrogen source and a phosphorus source for co-fermentation to prepare liquid feed, so that full-amount resource utilization of the kitchen wastewater is finally realized.

Description

Technical Field

[0001] This invention belongs to the field of waste resource utilization technology, and in particular relates to a method for the full resource utilization of kitchen waste. Background Technology

[0002] Food waste, as a complex solid waste, is mainly composed of three phases: swill oil, kitchen wastewater, and kitchen solid residue. Most current food waste treatment technologies separate the components of food waste and then reduce or recycle the individual phases.

[0003] For kitchen wastewater, current engineering treatment technologies involve oil extraction followed by discharge of the de-oiled wastewater as general domestic sewage into wastewater treatment plants. This wastewater is then treated using a combination of aerobic, anaerobic, and membrane bioreactor processes to ultimately meet discharge standards. These technologies are relatively well-developed and achieve high removal rates for organic matter and ammonia nitrogen, among other water pollutants, from kitchen wastewater. For example, in a typical single-treatment process like oxidation ditch treatment, under conditions of an average sludge concentration of 1112 mg / L and a hydraulic retention time of 20 h, the removal rates for COD, ammonia nitrogen, and animal and vegetable oils in kitchen wastewater can reach 89.8%, 96.5%, and 100%, respectively. In a combined treatment process like ABR-SBR, with a retention time of 14 h in the ABR, 7 h of aeration in the SBR, followed by 2 h of stirring under anoxic conditions and a final sedimentation time of 50 min, the removal rates for COD, ammonia nitrogen, and TN in kitchen wastewater can reach 86%, 92%, and 75%, respectively. However, this treatment approach aims to reduce pollutant levels to meet emission standards, failing to effectively utilize the nutrients in kitchen wastewater. Furthermore, some kitchen wastewater resource utilization technologies cannot achieve full resource utilization due to ingredient ratios. Moreover, existing kitchen wastewater resource utilization technologies can only partially utilize the wastewater; the excess is still discharged as sewage into wastewater treatment plants, thus failing to achieve full resource utilization. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for the full resource utilization of kitchen waste, which in particular effectively utilizes kitchen wastewater. The kitchen wastewater is used as a nutrient additive and moisture regulator to promote the growth and development of black soldier fly larvae and increase the accumulation of nutrients in the black soldier fly larvae.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for the complete resource utilization of food waste, comprising the following steps:

[0007] (1) Kitchen waste is separated into kitchen solid residue, kitchen wastewater and swill oil through three-phase separation;

[0008] (2) Add methanol to the swill oil and pre-esterify it under acidic catalyst conditions, then add methanol to perform transesterification under alkaline catalyst conditions to obtain biodiesel.

[0009] (3) Mix the kitchen waste residue, kitchen wastewater and straw to prepare animal feed;

[0010] (4) Add 3-day-old black soldier fly larvae to the animal feed and add kitchen wastewater every other day for bioconversion. After the bioconversion is completed, separate the insect sand organic fertilizer raw material and black soldier fly larvae. The mass-volume ratio of the animal feed to the kitchen wastewater added every other day is 89:1.6-2.2.

[0011] (5) Mix dried and crushed black soldier fly larvae, soybean meal, corn, rapeseed meal, quicklime and premixed feed to prepare mixed feed. Mix the mixed feed with kitchen wastewater and then add fermentation agent for anaerobic fermentation to obtain animal liquid feed.

[0012] Preferably, before the three-phase separation in step (1), the kitchen waste is further subjected to solid-liquid separation treatment, sorting and screening treatment, crushing treatment, and high-temperature sterilization treatment.

[0013] Preferably, in step (1), the water content of the kitchen solid residue is below 70%, and the oil content of the kitchen wastewater is below 5%.

[0014] Preferably, in step (3), the mass ratio of kitchen waste residue, kitchen wastewater and straw is 5-16:0.5-3.5:0.5-1.5; the straw includes one or more of sorghum straw, corn straw, Job's tears straw, soybean straw and rice straw.

[0015] Preferably, in step (4), the mass ratio of animal feed to 3-day-old black soldier fly is 150 to 1050:1.

[0016] Preferably, in step (4), the temperature of the biotransformation is 25-35°C, the humidity is 55%-70%, and the biotransformation time is 7-12 days.

[0017] Preferably, in step (5), the mass ratio of black soldier fly larvae: soybean meal: corn: rapeseed meal: quicklime: premix in the mixed feed is 5-15: 16.6-19.7: 54.4-61.8: 2.5-3.2: 6.3-6.5: 5; the mass ratio of the accessed kitchen wastewater to the mixed feed is 1:1.5; and the mass ratio of the fermentation agent to the mixed feed is 1:600.

[0018] Preferably, in step (5), the fermentation agent is one or more of yeast, lactic acid bacteria and Bacillus.

[0019] Preferably, in step (5), the fermentation pH is 4-6, the fermentation temperature is 25-35℃, and the fermentation time is 2-4 days.

[0020] Preferably, the high-temperature sterilization process involves sterilizing at 110–135°C and 0.4–1.2 kPa for 0.5–2 hours.

[0021] The present invention also provides an application of the liquid animal feed prepared by the above method in improving the egg production performance of laying hens.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention provides a method for the complete resource utilization of kitchen waste. It utilizes the swill oil separated from kitchen waste to produce biodiesel, and mixes the separated kitchen solids and wastewater with straw to prepare animal feed, thus achieving the complete resource utilization of kitchen waste. Furthermore, this invention uses kitchen wastewater as a nutrient and moisture regulator to promote the reproduction and development of black soldier flies, thereby obtaining black soldier flies with high nutrient content and high-quality insect-sand organic fertilizer raw materials. The black soldier flies produced by bioconversion and kitchen wastewater are then used as nitrogen and phosphorus sources for co-fermentation to prepare liquid feed, ultimately achieving the complete resource utilization of kitchen wastewater. Attached Figure Description

[0024] Figure 1 The effect of the amount of kitchen wastewater added on the body length of black soldier fly larvae;

[0025] Figure 2 The effect of the amount of kitchen wastewater added on the body weight of black soldier fly larvae;

[0026] Figure 3 The effect of the amount of kitchen wastewater added on the conversion efficiency of kitchen solids. Detailed Implementation

[0027] This invention provides a method for the complete resource utilization of food waste, comprising the following steps:

[0028] (1) Kitchen waste is separated into kitchen solid residue, kitchen wastewater and swill oil through three-phase separation;

[0029] (2) Add methanol to the swill oil and pre-esterify it under acidic catalyst conditions, then add methanol to perform transesterification under alkaline catalyst conditions to obtain biodiesel.

[0030] (3) Mix the kitchen waste residue, kitchen wastewater and straw to prepare animal feed;

[0031] (4) Add 3-day-old black soldier fly larvae to the animal feed and add kitchen wastewater every other day for bioconversion. After the bioconversion is completed, separate the insect sand organic fertilizer raw material and black soldier fly larvae. The mass-volume ratio of the animal feed to the kitchen wastewater added every other day is 89:1.6-2.2.

[0032] (5) Dry and crushed black soldier fly larvae, soybean meal, corn, rapeseed meal, quicklime and premixed feed are mixed to prepare mixed feed. The mixed feed is stirred with kitchen wastewater and then fermented with fermentation agent for anaerobic fermentation to obtain animal liquid feed.

[0033] In this invention, kitchen waste undergoes three-phase separation to obtain kitchen solid residue, kitchen wastewater, and swill oil. As a preferred embodiment, before three-phase separation, the kitchen waste is further subjected to solid-liquid separation, sorting and screening, crushing, and high-temperature sterilization. The solid-liquid separation method preferably employs a spiral dewatering machine to obtain oily kitchen wastewater and kitchen solid waste. Further, the total compression ratio of the spiral dewatering machine is approximately 1.56. After solid-liquid separation, sorting and screening are performed to remove metals and other inert impurities, resulting in screened kitchen solid waste. After sorting and screening, the screened kitchen solid waste is crushed. The crushing process preferably uses a crusher to obtain crushed kitchen solid waste and oily kitchen wastewater. The single-blade tangential force of the crusher is preferably 450N, and the moisture content of the crushed kitchen solid waste is below 60%, with a particle size of 1–10 mm. This invention utilizes a crushing and extrusion process to remove screened kitchen waste. This not only thoroughly separates the moisture from the kitchen waste, extracting more oil, but also makes the crushed kitchen waste more easily digestible and absorbable by carrion-eating insects. After crushing, the crushed kitchen waste and oily kitchen wastewater undergo high-temperature sterilization. The preferred sterilization method is sterilization at 110–135°C and 0.4–1.2 kPa for 0.5–2 hours, yielding sterilized kitchen waste and oily kitchen wastewater. Finally, the sterilized kitchen waste and oily kitchen wastewater are subjected to three-phase separation to obtain kitchen solids, kitchen wastewater, and swill oil. The preferred moisture content of the kitchen solids in this invention is below 70%, and the preferred oil content of the kitchen wastewater is below 5%.

[0034] This invention fully utilizes the kitchen waste solids, kitchen wastewater, and swill oil separated from kitchen waste, and prepares biodiesel from the swill oil: Methanol is added to the swill oil, and pre-esterification is carried out under acidic catalyst conditions. After the reaction reaches an acid value of 3-5 mg KOH / g, the byproduct water is removed. Then, methanol is added again for transesterification under alkaline catalyst conditions. After the reaction reaches an acid value of 1 mg KOH / g, methanol impurities are separated to obtain biodiesel feedstock. The pre-esterification reaction temperature is 60-80℃, the reaction time is 30-60 min, the acidic catalyst is preferably 98% concentrated sulfuric acid, the pre-esterification reaction vacuum degree is 0.1 MPa, and the mass ratio of swill oil to methanol is 7-10:1. During the transesterification reaction, the alkaline catalyst is preferably 3% sodium hydroxide, the transesterification reaction temperature is 60-70℃, the reaction time is 10-20 h, and the transesterification reaction vacuum degree is 0.1 MPa. This invention utilizes a mixture of kitchen waste residue, kitchen wastewater, and straw to prepare animal feed. The preferred mass ratio of the kitchen waste residue, kitchen wastewater, and straw is 5–16:0.5–3.5:0.5–1.5. The straw preferably includes one or more of sorghum straw, corn straw, Job's tears straw, soybean straw, and rice straw. The straw is preferably dried and pulverized. This invention does not have specific limitations on the method of drying and pulverizing the straw; methods known in the art can be used. Adding straw powder to the substrate increases its porosity, making it fluffy and thus inhibiting the formation of an anaerobic environment. To further utilize the kitchen wastewater, when feeding 3-day-old black soldier flies with animal feed, 70–120 mL of kitchen wastewater is added every other day for bioconversion. This invention uses kitchen wastewater as a nutrient additive and moisture regulator, increasing the nutrient source for black soldier fly larvae. However, excessive addition of kitchen wastewater can inhibit the growth and development of black soldier fly larvae and even cause their death, while insufficient addition is also detrimental to their growth and development. A further preferred embodiment involves adding 80-110 mL of kitchen wastewater every one day. The preferred method for selecting 3-day-old black soldier fly larvae is to place the eggs in a breathable incubation box and incubate them at 28°C for 36 hours. After incubation, the eggs are transferred to wheat bran with a moisture content of 60%-65% and kept for 3 days (at the end of the incubation period, the average body length, average body width, and average weight of the black soldier fly larvae are 4.41 mm, 1.25 mm, and 0.002 g, respectively). Then, black soldier fly larvae of suitable size and similar shape are sieved out, from which healthy and active 3-day-old larvae are selected. The preferred mass ratio of animal feed to 3-day-old black soldier fly larvae is 150–1050:1, more preferably 500–1010:1. The preferred temperature for the bioconversion is 25–35°C, the preferred humidity is 55%–70%, and the preferred bioconversion time is 7–12 days.This invention utilizes the aforementioned biotransformation method to meet the growth requirements of 3-day-old black soldier fly larvae while simultaneously promoting their growth and development, significantly increasing the nutrient content (such as crude protein content) of the larvae. In this invention, insect-sand organic fertilizer raw materials and black soldier fly larvae are separated. The separation employs a combination of fan-heated separation and intermittent sealing, whereby most insects are first separated using a sieve at 40°C, and then the insect-sand is sealed for 12 hours before collecting the insects on its surface. The insect separation rate is approximately 70-90%. In this invention, insect-sand refers to the remaining kitchen waste residue after the waste from food waste treatment has been transformed by black soldier flies. To further utilize kitchen wastewater, the separated black soldier fly larvae are dried and crushed. The dried and crushed larvae, soybean meal, corn, rapeseed meal, quicklime, and premixed feed are mixed to prepare a mixed feed. This mixed feed is then stirred with kitchen wastewater and inoculated with fermentation agents for anaerobic fermentation to obtain liquid animal feed. The preferred method for drying and crushing the black soldier fly larvae is drying and crushing at 105℃. The mass ratio of black soldier fly larvae: soybean meal: corn: rapeseed meal: quicklime: premix in the mixed feed is 5-15: 16.6-19.7: 54.4-61.8: 2.5-3.2: 6.3-6.5: 5. In the mixed feed of this invention, the crude protein content of the crushed and dried black soldier fly larvae is preferably 30.7%, the crude protein content of soybean meal is preferably 40.9%, the crude protein content of corn is preferably 7.2%, and the crude protein content of rapeseed meal is preferably 21.2%. The mass ratio of the introduced kitchen wastewater to the mixed feed is 1:1.5. The mass ratio of the fermentation agent to the mixed feed is 1:600. The fermentation agent is one or more of yeast, lactic acid bacteria, and Bacillus. The fermentation pH is 4-6, the fermentation temperature is 25-35℃, and the fermentation time is 2-4 days. The high-temperature sterilization process involves sterilizing at 110–135°C and 0.4–1.2 kPa for 0.5–2 hours.

[0035] The crushed insect feed ingredients in this invention are rich in crude protein and crude fat, providing a large amount of nitrogen. Sterilized kitchen wastewater, used instead of tap water, can also provide a large amount of nitrogen and phosphorus as a raw material for liquid feed preparation. Therefore, the animal liquid feed prepared using both as raw materials is rich in nutrients and has broad application prospects. Thus, this invention provides an application of the animal liquid feed prepared by the above method in improving the egg production performance of laying hens.

[0036] The advantages of the method for full resource utilization of kitchen waste of the present invention are as follows: (1) Combining kitchen solid residue with kitchen wastewater simplifies the entire kitchen waste treatment process and saves treatment costs. (2) By adding kitchen wastewater to the kitchen solid residue in the bioconversion of black soldier fly larvae, the black soldier fly larvae and insect sand produced have a higher nutrient content than the black soldier fly and insect sand organic fertilizer raw materials produced by the traditional black soldier fly bioconversion of kitchen waste, while further utilizing kitchen wastewater. (3) The produced insect sand organic fertilizer raw material is rich in crude fiber, making it more competitive as an organic fertilizer raw material than traditional organic fertilizer raw materials. (4) Compared with anaerobic fermentation and aerobic composting processes, the treatment process of the present invention has simpler process conditions, lower management costs, and is easier to promote. (5) It realizes the synergistic resource utilization treatment of straw powder, kitchen waste treatment residue, and kitchen waste treatment wastewater.

[0037] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0038] In the following embodiments, the fermentation agent and premix of the present invention were purchased from the Taobao platform. The fermentation agent was EM mixed agent (the main component of Bacillus subtilis OKH0406), and the premix was 5% laying hen premix.

[0039] In the following examples, the premixed feed per kilogram of feed contains: Vitamin A (retinol) 9999 IU; Vitamin B2 (riboflavin) 3.2 mg; Vitamin B6 (pyridoxine) 2.0 mg; Vitamin D3 (cholecalciferol) 4998 IU; Vitamin E (α-tocopherol) 19.2 mg; Vitamin K3 1.5 mg; Niacin 25.5 mg; Pantothenate 9.9 mg; Folic acid 0.5 mg; Manganese 60 mg; Iron 60 mg; Zinc 60 mg; Copper 8.1 mg; Iodine 0.9 mg; Selenium 0.48 mg.

[0040] Example 1

[0041] A method for the complete resource utilization of kitchen waste includes the following steps:

[0042] (1) The kitchen waste is drained by a spiral dewatering machine to obtain oily kitchen wastewater and kitchen solid waste. Metal and other inert impurities are removed by sorting and screening to obtain screened kitchen solid waste. The screened kitchen solid waste is crushed by a crusher to obtain crushed kitchen solid waste and oily kitchen wastewater. The crushed kitchen solid waste and oily kitchen wastewater are then sterilized at 140℃ and 0.4Mpa for 0.5 hours to obtain sterilized kitchen solid waste and oily kitchen wastewater. The kitchen solid residue, kitchen wastewater and swill oil are obtained by three-phase separation. The water content of the kitchen solid residue is controlled below 70%, and the oil content of the kitchen wastewater is within 5%.

[0043] (2) 140 catties of swill oil was added to 35 catties of methanol and pre-esterified for 50 min at 70℃, vacuum degree of 0.1 MPa and catalysis of 98% concentrated sulfuric acid. After the reaction reached an acid value of 3-5 mg KOH / g, the by-product water was removed. Then, excess methanol was added and transesterified for 15 h at 65℃, vacuum degree of 0.1 MPa and catalysis of 3% sodium hydroxide to obtain 110 catties of biodiesel feedstock.

[0044] (3) Mix 1.1t of the kitchen waste residue, 0.1t of sorghum straw powder (moisture content 10%), and 0.3t of the kitchen wastewater to obtain 1.5t of animal feed. Add 10 catties of 3-day-old black soldier fly larvae and add 40,000 mL of kitchen wastewater every other day. Convert for 11 days at 30℃ and 55%-70% humidity. After the conversion is completed, the insect sand is separated by an insect sand separation device. The separation adopts a combination of fan thermal separation and intermittent sealing. That is, most of the black soldier fly larvae are separated by a screen at 40℃ first. Then, the insect sand is sealed for 12 hours and the black soldier fly larvae on the surface of the insect sand are collected to obtain 0.3t of insect sand organic fertilizer raw material and 1t of black soldier fly larvae.

[0045] (4) Dry and crush the black soldier fly larvae at 105℃. Take 200 catties of dried and crushed black soldier fly larvae, 221 catties of soybean meal, 724 catties of corn, 33 catties of rapeseed meal, 87 catties of quicklime and 66.5 catties of premixed feed and mix them. After mixing, pour in 0.85 t of kitchen wastewater and stir to ensure that the moisture content of the feed raw materials after mixing is 60% to 70%. Add 2.5 catties of fermentation agent and anaerobic ferment for 3 days at a fermentation temperature of 30℃ and a fermentation pH of 5 to obtain fermented animal liquid feed with a pH of 4 to 4.5.

[0046] Example 2

[0047] A method for the complete resource utilization of kitchen waste includes the following steps:

[0048] (1) The kitchen waste is drained by a spiral dewatering machine to obtain oily kitchen wastewater and kitchen solid waste. Metal and other inert impurities are removed by sorting and screening to obtain screened kitchen solid waste. The screened kitchen solid waste is crushed by a crusher to obtain crushed kitchen solid waste and oily kitchen wastewater. The crushed kitchen solid waste and oily kitchen wastewater are then sterilized at 140℃ and 0.4Mpa for 0.5 hours to obtain sterilized kitchen solid waste and oily kitchen wastewater. The kitchen solid residue, kitchen wastewater and swill oil are obtained by three-phase separation. The water content of the kitchen solid residue is controlled below 70%, and the oil content of the kitchen wastewater is within 5%.

[0049] (2) 70 catties of swill oil was added to 10 catties of methanol and pre-esterified for 60 min at 60℃, vacuum degree of 0.1 MPa, and catalysis of 98% concentrated sulfuric acid. After the reaction reached an acid value of 3-5 mg KOH / g, the by-product water was removed. Then, excess methanol was added and transesterified for 20 h at 60℃, vacuum degree of 0.1 MPa, and catalysis of 3% sodium hydroxide to obtain 57 catties of biodiesel feedstock.

[0050] (3) Mix 0.6t of the kitchen waste residue, 0.05t of corn straw powder, and 0.1t of kitchen wastewater to obtain 0.75t of animal feed. Add 8 catties of 3-day-old black soldier fly larvae and add 20,000 mL of kitchen wastewater every other day. Convert for 11 days at 35℃ and 55% to 70% humidity. After the conversion is completed, the insect sand is separated by an insect sand separation device. The separation adopts a combination of fan thermal separation and intermittent sealing. That is, most of the black soldier fly larvae are separated by a screen at 40℃ first. Then, the insect sand is sealed for 12 hours and the black soldier fly larvae on the surface of the insect sand are collected to obtain 0.3t of insect sand organic fertilizer raw material and 0.5t of black soldier fly larvae.

[0051] (4) Dry and crush the black soldier fly larvae at 105℃. Take 100 catties of dried and crushed black soldier fly larvae, 110 catties of soybean meal, 362 catties of corn, 17 catties of rapeseed meal, 43 catties of quicklime and 33.3 catties of premixed feed and mix them. After mixing, pour in 0.42 t of kitchen wastewater and stir to ensure that the moisture content of the feed raw materials after mixing is 60% to 70%. Add 1.25 catties of fermentation agent and anaerobic ferment for 4 days at 25℃ and a fermentation pH of 6 to obtain fermented animal liquid feed with a pH of 4 to 4.5.

[0052] Example 3

[0053] A method for the complete resource utilization of kitchen waste includes the following steps:

[0054] (1) The kitchen waste is drained by a spiral dewatering machine to obtain oily kitchen wastewater and kitchen solid waste. Metal and other inert impurities are removed by sorting and screening to obtain screened kitchen solid waste. The screened kitchen solid waste is crushed by a crusher to obtain crushed kitchen solid waste and oily kitchen wastewater. The crushed kitchen solid waste and oily kitchen wastewater are then sterilized at 140℃ and 0.4Mpa for 0.5 hours to obtain a mixture of sterilized kitchen solid waste and oily kitchen wastewater. The mixture is separated into kitchen solid residue, kitchen wastewater and swill oil by three-phase separation. The moisture content of the kitchen solid residue is controlled below 70%, and the oil content of the kitchen wastewater is within 5%.

[0055] (2) Add 0.5 catties of methanol to 5 catties of swill oil and pre-esterify it for 30 min at 80℃, vacuum degree of 0.1 MPa, and catalysis of 98% concentrated sulfuric acid. After the reaction reaches an acid value of 3-5 mg KOH / g, remove the by-product water. Then add excess methanol and transesterify it for 10 h at 70℃, vacuum degree of 0.1 MPa, and catalysis of 3% sodium hydroxide to obtain 4 catties of biodiesel feedstock.

[0056] (3) Mix 60 catties of the aforementioned kitchen waste residue, 3.5 catties of Job's tears straw powder, and 15 catties of the aforementioned kitchen wastewater to obtain 78.5 catties of animal feed. Add 200 g of 3-day-old black soldier fly larvae and 750 mL of kitchen wastewater every other day. Convert for 11 days at 35℃ and 55%–70% humidity. After the conversion is completed, the insect sand is separated by an insect sand separation device. The separation adopts a combination of fan thermal separation and intermittent sealing. That is, most of the black soldier fly larvae are separated by a screen at 40℃ first. Then, the insect sand is sealed for 12 hours and the black soldier fly larvae on the surface of the insect sand are collected to obtain 31 catties of insect sand organic fertilizer raw material and 80 catties of black soldier fly larvae.

[0057] (4) Dry and crush the black soldier fly larvae at 105℃. Take 5 catties of dried and crushed black soldier fly larvae, 5.48 catties of soybean meal, 17.95 catties of corn, 0.83 catties of rapeseed meal, 2.15 kg of quicklime and 1.65 catties of premixed feed and mix them. After mixing, pour in 49.6 catties of kitchen wastewater and stir to ensure that the moisture content of the feed raw materials after mixing is 60% to 70%. Add 27.5 g of fermentation agent and anaerobic ferment for 2 days at 35℃ and a fermentation pH of 4 to obtain fermented animal liquid feed with a pH of 4 to 4.5.

[0058] Example 4

[0059] The difference between this embodiment and embodiment 1 is that in step (3), in this embodiment, 4000g of the kitchen waste residue, 250g of sorghum straw powder (moisture content 10%), and 800g of the kitchen wastewater are mixed to obtain animal feed, and 5g of 3-day-old black soldier flies are added, with 80mL of kitchen wastewater added every other day. The remaining steps of this embodiment are the same as those of embodiment 1.

[0060] Example 5

[0061] The difference between this embodiment and embodiment 4 is that in step (3), 110 mL of kitchen wastewater is added every other day. The remaining steps of this embodiment are the same as those of embodiment 4.

[0062] Example 6

[0063] The difference between this embodiment and embodiment 4 is that in step (3), this embodiment mixes 4000g of the kitchen solid residue, 250g of sorghum straw powder (moisture content of 10%) and 800g of the kitchen wastewater to obtain animal feed, adds 5g of 3-day-old black soldier fly larvae, and adds 140mL of kitchen wastewater every other day. The remaining steps of this embodiment are the same as those of embodiment 4.

[0064] Example 7

[0065] The difference between this embodiment and Embodiment 1 is that step (4) in this embodiment is as follows: Black soldier fly larvae are dried and crushed at 105℃. 66.6 catties of dried and crushed black soldier fly larvae, 262.4 catties of soybean meal, 823.2 catties of corn, 42.6 catties of rapeseed meal, 83.9 catties of quicklime, and 66.6 catties of premix are mixed. After mixing, 0.85 t of kitchen wastewater is added and stirred to ensure that the moisture content of the feed ingredients after mixing is 60% to 70%. 2.5 catties of fermentation agent is added, and anaerobic fermentation is carried out for 3 days at a fermentation temperature of 30℃ and a fermentation pH of 5 to obtain fermented animal liquid feed with a pH of 4 to 4.5. The remaining steps of this embodiment are the same as in Embodiment 1.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 4 is that in step (3), this comparative example mixes 4000g of the kitchen waste residue, 250g of sorghum straw powder (moisture content of 10%), and 800g of tap water to obtain animal feed, adds 5g of 3-day-old black soldier fly larvae, and does not add kitchen wastewater every other day thereafter. The remaining steps of this comparative example are the same as those of Example 4.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Example 4 is that in step (3), this comparative example mixes 4000g of the kitchen waste residue, 250g of sorghum straw powder (moisture content of 10%), and 800g of the kitchen wastewater to obtain animal feed, adds 5g of 3-day-old black soldier fly larvae, and does not add kitchen wastewater every other day thereafter. The remaining steps of this comparative example are the same as those of Example 4.

[0070] Comparative Example 3

[0071] The difference between this comparative example and Example 4 is that in step (3), this comparative example mixes 4000g of the kitchen waste residue, 250g of sorghum straw powder (moisture content of 10%), and 800g of the kitchen wastewater to obtain animal feed, adds 5g of 3-day-old black soldier fly larvae, and adds 50mL of kitchen wastewater every other day. The remaining steps of this comparative example are the same as those of Example 4.

[0072] Comparative Example 4

[0073] The difference between this comparative example and Example 1 is that step (4) in this comparative example is as follows: 298.256 catties of soybean meal, 840.1765 catties of corn, 46.6025 catties of rapeseed meal, 79.89 catties of quicklime, and 66.575 catties of premix are mixed. After mixing, 0.85 t of kitchen wastewater is added and stirred to ensure that the moisture content of the feed ingredients after mixing is 60% to 70%. 2.5 catties of fermentation inoculant is added, and the mixture is anaerobic fermented for 3 days at a fermentation temperature of 30°C and a fermentation pH of 5 to obtain fermented animal liquid feed with a pH of 4 to 4.5. The remaining steps of this comparative example are the same as those in Example 1.

[0074] Comparative Example 5

[0075] The difference between this comparative example and Example 1 is that step (4) in this comparative example is as follows: Black soldier fly larvae are dried and crushed at 105℃. 332.9 catties of dried and crushed black soldier fly larvae, 186.4 catties of soybean meal, 631.2 catties of corn, 29.3 catties of rapeseed meal, 85.2 catties of quicklime, and 66.6 catties of premix are mixed. After mixing, 0.85 t of kitchen wastewater is added and stirred to ensure that the moisture content of the feed ingredients after mixing is 60% to 70%. 2.5 catties of fermentation inoculant is added, and anaerobic fermentation is carried out for 3 days at a fermentation temperature of 30℃ and a fermentation pH of 5 to obtain fermented animal liquid feed with a pH of 4 to 4.5. The remaining steps of this comparative example are the same as those in Example 1.

[0076] Experimental Example 1

[0077] 1. Materials and Methods

[0078] 1.1 Experimental Materials

[0079] Black soldier fly larvae eggs were obtained from a black soldier fly larvae breeding company in Zunyi City, Guizhou Province.

[0080] The basic physicochemical properties of the kitchen waste in Example 4 are shown in Table 1.

[0081] The basic physicochemical properties of the kitchen wastewater prepared in Example 4 are shown in Table 2.

[0082] Table 1. Basic physicochemical properties of kitchen waste from Example 4

[0083]

[0084] Table 2. Basic physicochemical properties of the kitchen wastewater prepared in Example 4

[0085]

[0086]

[0087] 1.2 Experimental Methods

[0088] The treatment method for group CK is Comparative Example 1, the treatment method for group T1 is Comparative Example 2, the treatment method for group T50 is Comparative Example 3, the treatment method for group T80 is Example 4, the treatment method for group T110 is Example 5, and the treatment method for group T140 is Example 6.

[0089] 1.3 Measurement Indicators

[0090] After the conversion began, the body length, body width, and weight of black soldier fly larvae were recorded every day (5 larvae were randomly selected, recorded, and then released). The pH of the insect sand was also recorded using a soil acidity meter. On the 11th day of conversion, the insect sand was separated from the black soldier fly larvae, dried, and crushed. The body composition of the black soldier fly larvae (crude protein, crude fat, crude ash, salt, total phosphorus, calcium, and dry matter), the nutrient content of the insect sand organic fertilizer raw material (crude protein, crude fat, crude fiber, organic matter, pH, total nitrogen, total phosphorus, and total potassium), and the conversion effect of kitchen waste (reduction rate of kitchen waste solid waste, insect production rate of kitchen waste solid waste, and larval yield) were also recorded.

[0091] 1.3.1 Formulas related to the indicators

[0092] Food waste solids reduction rate = (W1-W2) / W1×100%

[0093] Insect infestation rate in kitchen waste residue = (W4-W3) / (W1-W2)×100%

[0094] In the formula, W1 is the dry weight of kitchen solid residue before conversion, W2 is the dry weight of kitchen solid residue after conversion, W3 is the dry weight of black soldier fly larvae before conversion, and W4 is the dry weight of black soldier fly larvae after conversion.

[0095] 1.3.2 Indicator Measurement Methods

[0096] Crude protein was determined by multiplying total nitrogen by 6.25 (see Finke MD, Estimate of chitin in raw whole insects. Zoo Biol, 2007, 26:105-115); total nitrogen was determined by the Dumas method (see ISO 16634-1:2008, Food products—Determination of the total nitrogen content by combustion according to the Dumas principle and calculation of the crude protein content—Part 1: Oilseeds and animal feeding stuffs. International Organization for Standardization, Geneva, Switzerland); crude fat was determined by the Soxhlet method (see ISO 6492:1999, Animal feeding stuffs—Determination of fat content. International Organization for Standardization, Geneva, Switzerland). Crude fiber was determined by the General method (see BS 6215-1-1981, Methods of test for agricultural food products—Determination of crude fiber content (general method)). The crude ash content was determined by the AOAC method (see John JL St. Report on Ash [J]. Journal of AOAC INTERNATIONAL, 1943, 26(02).); the organic matter content was determined by the Walkley-Black method (see Walkley AJ, Black IA. Estimation of soil organic carbon by the chromic acid titration method. Soil Science, 1934, 37(01): 29-38).Total potassium was determined using the flame-emission spectrometry method (see ISO 7485-2000, Animal feeding stuffs—Determination of potassium and sodium contents—Methods using flame-emission spectrometry, International Organization for Standardization, 2000.); calcium was determined using the EDTA method (see Joseany MS Almeida, Rafael M Dornellas, Sakae Yotsumoto-Neto, et al. A simple electroanalytical procedure for the determination of calcium in biodiesel[J]. Fuel, 2014, 115(Jan.):658-665.); total phosphorus was determined using a fully automated analyzer; moisture was determined using method A in ISO 662 (see Animal and vegetable fats and oils—Determination of moisture and volatile matter content(ISO 662:1998); German version EN ISO 662:2000.); salt content was determined using the Mohr method (see Block). Jacob andWaters OscarB..Interference of the ammoniiunion in Mohr's method for the determination of chloride[J].Talanta,1967,14(09):1130-1131.). .

[0097] 1.4 Data Processing

[0098] Experimental data and graphs were processed using Excel 2020 and Origin 2018, and significance analysis was performed using SPSS 17.0.

[0099] 2 Results and Discussion

[0100] 2.1 Effects of different amounts of kitchen wastewater added on the growth and development of black soldier fly larvae

[0101] Depend on Figure 1It was observed that during days 1-3 of transformation, the body length of black soldier fly larvae in group CK was greater than that in groups T50, T80, T110, T140, and T1. However, during days 5-7 of transformation, the body length of black soldier fly larvae in groups T50, T80, T110, and T140 was greater than that in group CK. During days 7-11 of transformation, the growth and development of black soldier fly larvae in groups T50, T80, T110, and T140 tended to slow down, with the body length of black soldier fly larvae in group T110 being the largest. Furthermore, throughout the entire transformation period, the body length of black soldier fly larvae in group T1 remained the lowest among the six experimental groups.

[0102] Depend on Figure 2 It was observed that during days 1-5 of transformation, the black soldier fly larvae in the CK group had a greater body weight than those in T1, T50, T80, T110, and T140. During days 7-11 of transformation, the black soldier fly larvae in T50, T80, T110, and T140 had a greater body weight than those in the CK group, with the black soldier fly larvae in T110 having the largest body weight at this time. Furthermore, throughout the entire transformation period, the black soldier fly larvae in the T1 group generally had the lowest body weight.

[0103] Therefore, during days 1-3 of the conversion, the black soldier fly larvae in the CK group showed better growth and development than those in the groups receiving de-oiled kitchen wastewater. During days 3-9 of the conversion, the black soldier fly larvae in the T50, T80, T110, and T140 groups showed better growth and development than the CK group. This may be because the gut bacterial community of the black soldier fly larvae gradually became richer, allowing them to adapt to the rearing environment composed of kitchen waste residue, sorghum straw, and de-oiled kitchen wastewater. Furthermore, the de-oiled kitchen wastewater itself is rich in absorbable reducing sugars, amino acids, fatty acids, and other small-molecule soluble substances, providing more nutrients for the black soldier fly larvae. The regularly added kitchen wastewater also replenished the moisture in the feed, promoting the growth and development of the larvae. Therefore, the changes in the body length and weight of the black soldier fly larvae show that adding kitchen wastewater every one day, after 3 days of bioconversion, promoted the growth and development of the black soldier fly larvae.

[0104] Table 3. Effects of kitchen wastewater addition on the composition of black soldier fly larvae.

[0105]

[0106] Table 3 shows that the crude protein content of group T1 was significantly lower than that of group CK, while T80, T110, and T140 were significantly higher than those of group CK. Group T110 had the highest crude protein content, reaching 44.86%, an increase of 3.54% compared to group CK. This indicates that the addition of kitchen wastewater can significantly increase the crude protein content of black soldier fly larvae. Regarding total phosphorus content, group T110 was significantly higher than group CK, increasing by 0.07% relative to group CK. Crude ash, as an oxide produced after high-temperature combustion, is considered an indirect indicator of the organic matter content of the sample. Therefore, the results in Table 3 indicate that the addition of kitchen wastewater can provide black soldier fly larvae with more nutrients.

[0107] 2.2 Effect of Kitchen Wastewater Addition on Nutrient Content of Insect Sand

[0108] Table 4. Effects of Kitchen Wastewater Addition Amount on Nutrient Content of Insect Sand

[0109]

[0110]

[0111] Table 4 shows that the crude protein content of the insect sand in the T50, T80, T110, and T140 groups was significantly higher than that in the CK group. There was no significant difference in crude fat content among the insect sand added with degreased kitchen wastewater, and all groups had higher levels than the CK group. Regarding crude fiber content, the crude fiber content in the insect sand added with kitchen wastewater was higher than that in the CK group. As for organic matter content, the organic matter content of each experimental group ranged from 69.40% to 74.54%, with T80, T110, and T140 groups significantly higher than the CK group. The T140 group had the highest organic matter content, increasing by 5.14% compared to the CK group. The above data analysis indicates that the addition of kitchen wastewater increased the content of crude protein, crude fat, crude fiber, organic matter, total nitrogen, total phosphorus, and total potassium in the insect sand.

[0112] 2.3 Effect of kitchen wastewater addition on kitchen solids conversion efficiency

[0113] Depend on Figure 3The results showed that the reduction rate of kitchen waste solids in groups T1 and T140 was significantly lower than that in group CK. There were no significant differences between groups T50, T80, T110, and CK. Group T110 had the closest reduction rate to group CK, reaching 63.73%. Regarding the insect infestation rate in kitchen waste residue, groups T80 and T110 were significantly higher than other experimental groups, with group T110 having the highest rate at 29.79%, while group T1 had the lowest rate at only 21.82%. Therefore, the addition of kitchen wastewater increased the nutrient intake of black soldier fly larvae, allowing them to achieve higher levels of dry matter accumulation and faster feeding on kitchen waste solids, thus increasing the insect infestation rate. Data shows that too little or too much degreased kitchen wastewater will have an adverse effect on the conversion of kitchen waste residue by black soldier fly larvae. However, an appropriate amount of kitchen wastewater can increase the insect production rate of black soldier fly larvae on kitchen solid residue without significantly reducing the reduction rate of kitchen waste residue.

[0114] Experimental Example 2

[0115] The liquid animal feeds prepared in Examples 1, 7, 4, and 5 were used as experimental groups 1, 2, 1, and 2, respectively, and were fed to 45-week-old Lohmann Brown laying hens twice a day at a rate of 150 mL per bird for 5 consecutive weeks. Each experimental group had 3 replicates, with 8 birds per replicate. The number of eggs laid, egg weight, feed intake, and number of broken soft-shell eggs were recorded daily during the experiment. After the experiment, the egg production rate, feed conversion ratio, average egg weight, and broken soft-shell egg rate were calculated. The egg production rate was calculated as follows: egg production rate = [total number of eggs laid / (number of laying hens × number of days in the experiment)]; feed conversion ratio = total feed intake / total egg weight; average egg weight = total egg weight / total number of eggs laid; broken soft-shell egg rate = number of broken soft-shell eggs / daily egg production. The results are shown in Table 5.

[0116] Table 5. Performance indicators of laying hens in different groups

[0117]

[0118] Note: Different letters in the suffixes of data within the same row indicate significant differences (P < 0.05), while the same letter in the suffixes indicates no significant differences (P > 0.05).

[0119] Table 5 shows that, in terms of egg production rate, there was no significant difference between control groups 1 and 2, while experimental groups 1 and 2 were significantly higher than both control groups 1 and 2, with experimental group 2 being significantly higher than experimental group 1. Regarding the feed conversion ratio, there was no significant difference between control groups 1 and 2, while experimental groups 1 and 2 were significantly lower than both control groups 1 and 2, with experimental group 2 being significantly lower than experimental group 1. The average egg weight showed the same trend as the egg production rate in each experimental group. Regarding the rate of broken or soft eggs, there was no significant difference between control groups 1 and 2, while experimental groups 1 and 2 were significantly lower than both control groups 1 and 2, with experimental group 2 being significantly lower than experimental group 1. Therefore, the liquid animal feed of the present invention improves the egg production performance of laying hens.

[0120] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for the complete resource utilization of kitchen waste, characterized in that, Includes the following steps: (1) Kitchen waste is separated into kitchen solid residue, kitchen wastewater and swill oil through three-phase separation; (2) Add methanol to the swill oil and pre-esterify it under acidic catalyst conditions, then add methanol to perform transesterification under alkaline catalyst conditions to obtain biodiesel. (3) Mix the kitchen waste residue, kitchen wastewater and straw to prepare animal feed; (4) Add 3-day-old black soldier fly larvae to the animal feed and add kitchen wastewater every other day for bioconversion. After the bioconversion is completed, separate the insect sand organic fertilizer raw material and black soldier fly larvae. The mass-volume ratio of the animal feed to the kitchen wastewater added every other day is 89:1.6-2.

2. (5) Mix dried and crushed black soldier fly larvae, soybean meal, corn, rapeseed meal, quicklime and premix to prepare mixed feed. Mix the mixed feed with kitchen wastewater and then add fermentation agent for anaerobic fermentation to obtain animal liquid feed. In step (3), the mass ratio of kitchen waste residue, kitchen wastewater and straw is 5-16:0.5-3.5:0.5-1.5; the straw includes one or more of sorghum straw, corn straw, Job's tears straw, soybean straw and rice straw. In step (5), the mass ratio of black soldier fly larvae: soybean meal: corn: rapeseed meal: quicklime: premix in the mixed feed is 5-15:16.6-19.7:54.4-61.8:2.5-3.2:6.3-6.5:5; the mass ratio of the connected kitchen wastewater to the mixed feed is 1:1.5; and the mass ratio of the fermentation agent to the mixed feed is 1:

600.

2. The method according to claim 1, characterized in that, Before the three-phase separation in step (1), the kitchen waste is further subjected to solid-liquid separation treatment, sorting and screening treatment, crushing treatment and high-temperature sterilization treatment.

3. The method according to claim 1, characterized in that, In step (1), the water content of the kitchen solid residue is below 70%, and the oil content of the kitchen wastewater is below 5%.

4. The method according to claim 1, characterized in that, In step (4), the mass ratio of animal feed to 3-day-old black soldier flies is 150-1050:

1.

5. The method according to claim 1, characterized in that, In step (4), the temperature of the biotransformation is 25-35°C, the humidity is 55%-70%, and the biotransformation time is 7-12 days.

6. The method according to claim 1, characterized in that, In step (5), the fermentation agent is one or more of yeast, lactic acid bacteria and Bacillus; the fermentation pH is 4 to 6, the fermentation temperature is 25 to 35°C, and the fermentation time is 2 to 4 days.

7. The method according to claim 2, characterized in that, The high-temperature sterilization process involves sterilizing at 110–135°C and 0.4–1.2 kPa for 0.5–2 hours.

8. The application of the liquid animal feed prepared by the method according to any one of claims 1 to 7 in improving the egg production performance of laying hens.

Images