Method for resource utilization of leather residue solid waste

Abstract

The present invention belongs to waste treatment in the leather industry, and particularly refers to a method for resource utilization of leather meat residue solid waste. It includes process steps such as pretreatment, cleaning, high temperature and high pressure hydrolysis, enzymolysis, and degreasing. By adopting technical measures such as cleaning and desalting the leather meat residue, high temperature and high pressure hydrolysis, selecting a composite enzyme and controlling the enzymolysis conditions, a leather meat residue enzymolysis solution rich in total nitrogen and protein content is obtained. The present invention solves the problem of the current lack of effective resource utilization methods for leather meat residue solid waste, has mild reaction conditions, fast reaction speed, and is not easy to produce secondary pollution. The treated meat residue enzymolysis solution can be used as a nitrogen source for microbial fermentation, and the meat residue enzymolysis solution is made into spray-dried powder for easy storage and transportation.

Description

Technical Field

[0001] The invention belongs to waste treatment in the leather industry, and particularly refers to a method for resource utilization of leather slag solid waste. Background Art

[0002] In the traditional leather making process, a large amount of solid waste is generated every year. According to reports, about 70% of the raw leather used in the leather industry is not made into finished products, and a large amount of resources are not reasonably utilized, that is, they are turned into solid waste in the form of scraps, etc. The above solid wastes include hair and meat residues, scraps from the original leather, gray leather edges, and blue leather shavings. According to national environmental protection requirements, leather waste must be treated with corresponding measures before it can be discharged. However, due to the large investment, the burden on enterprises has increased, and a small number of private enterprises do not discharge pollutants as required. Although more than 80% of leather enterprises in my country have built waste treatment facilities, due to different treatment modes and investments, the treatment process of leather waste still cannot meet the requirements of effective reuse. Therefore, the current leather waste is still mainly piled up. Meat residue piles are easy to rot and stink, and they cannot meet the hygiene standards when used directly as feed. For example, the use of acid and alkali digestion to prepare oil will lead to high energy consumption and secondary pollution. Therefore, how to deal with a large amount of meat residue solid waste and make effective use of it is a problem that restricts the development of the leather industry and needs to be solved urgently.

[0003] The patent documents searched by the applicant are as follows:

[0004] The patent document with application number CN201811564065.3 discloses an enzymatic hydrolysis treatment method and an enzymatic hydrolysis treatment system for leather-making meat residue solid waste. The technical idea is to use the enzymatic hydrolysis treatment system to treat leather-making meat residue, and to recover the solid and liquid phases of the enzymatic hydrolysis products by filtering, separating and recovering, so as to achieve the purpose of resource utilization of the meat residue solid waste.

[0005] Patent document with publication number CN105010737A discloses a method for preparing meat powder based on tannery alkali skin and fleshing waste residue. The technical idea is to use mixed acid and hydrogen peroxide to drum stir the meat residue, then add alkali to obtain meat slurry, and then prepare meat pellets for feed and fertilizer by drying. Although this method uses meat residue to prepare meat pellets, a large amount of acid-containing wastewater is discharged during the production process, which pollutes the environment.

[0006] The applicant has not found any report identical or similar to the present application in the existing patent documents. Summary of the invention

[0007] The purpose of the present invention is to provide a method for resource utilization of leather residue solid waste, and the extracted hair and enzymatic hydrolysate have high industrial utilization value.

[0008] The overall technical concept of the present invention is:

[0009] The method for resource utilization of leather residue solid waste includes pretreatment and enzymatic hydrolysis; the process steps and process conditions are as follows:

[0010] A. Pretreatment

[0011] A1. Cleaning

[0012] Weigh 500 g to 600 g of leather residue, add 500 ml to 600 ml of water, place in a shaking bottle, and shake at a speed of 100 to 150 rpm for 150 to 240 minutes;

[0013] A2. High temperature and high pressure hydrolysis

[0014] Add 200ml to 300ml of water to the leather residue after A1 washing, and heat at 121℃ and 1.013×10 5 Heating at 1000 rpm for 2 to 3 hours;

[0015] B. Enzymatic hydrolysis

[0016] The meat residue hydrolyzate treated in step A2 is cooled to room temperature, and enzyme preparations are added in the following amounts: 0.3-0.4 g / L alkaline protease, 0.1-0.2 g / L alkaline lipase, and 0.1-0.2 g / L trypsin; after enzymolysis at 35°C-37°C and 100-150 rpm for 2-3 hours, insoluble matter is filtered out;

[0017] C. Fat removal

[0018] The meat residue enzymatic hydrolyzate after filtering out the insoluble matter is cooled at low temperature, and after the liquid and lipid parts are separated, the fat layer is removed, the insoluble matter is filtered out, and the filtrate is collected.

[0019] The main function of step A1 is to thoroughly clean the meat residue and wash away the salt on its surface.

[0020] The main function of step A2 is to hydrolyze the meat residue by high temperature and high pressure.

[0021] The main function of step B is to add protease into the meat residue hydrolyzate to hydrolyze it into various polypeptides and small molecule amino acids.

[0022] The applicant needs to explain that when selecting a composite enzyme preparation for enzymatic hydrolysis, it is necessary to fully consider the efficacy, optimal pH, optimal temperature, etc. of various enzyme preparations. Under certain conditions, one enzyme preparation will be a substrate for another enzyme preparation, or one enzyme preparation will have a certain activation effect on another enzyme preparation. Therefore, a lot of effort needs to be spent on experiments in terms of the selection, dosage, and action environment of enzyme preparations in order to obtain the corresponding enzymatic hydrolysis process.

[0023] The meat residue solid waste in this application contains a large amount of protein and fat. According to the enzyme specificity to the substrate, protease and lipase are selected for enzymatic hydrolysis respectively. Taking into account the action conditions of the composite enzyme preparation, after repeated experiments, it is finally determined that the composite enzyme preparation uses a combination of alkaline protease, alkaline lipase and trypsin.

[0024] The function of alkaline protease is to hydrolyze protein, but not fat. During the action process, it hydrolyzes peptide bonds, turning large molecular proteins into small molecular peptide chains and amino acids.

[0025] The function of alkaline lipase is to catalyze the hydrolysis of fat into glycerol and fatty acids.

[0026] The function of trypsin is to catalyze the hydrolysis of some amino acids and has a certain activation effect on other enzymes.

[0027] The specific technical concept of the present invention also includes:

[0028] In order to achieve a better cleaning effect on the meat residue, the preferred technical implementation means is that the oscillation in step A1 is to change the water every 30 to 40 minutes, and wash 5 to 6 times in total.

[0029] The various enzyme preparations added in step B of the present invention act on the protein in the meat residue. In order to fully hydrolyze it and obtain a good synergistic effect, the type and ratio of the enzyme preparations are particularly important. The preferred technical scheme is that the enzyme activity of the alkaline protease in step B is 200,000 U / g, the optimum temperature is 40°C to 50°C, and the optimum pH is 8.0; the enzyme activity of the alkaline lipase is 500 U / g, the optimum temperature is 35°C to 40°C, and the optimum pH is 7.5; the enzyme activity of the trypsin is 30,000 U / g, the optimum temperature is 35°C to 45°C, and the optimum pH is 7.5 to 8.0.

[0030] In order to better achieve the stratification of lipid and meat residue enzymatic hydrolysate and thus facilitate separation, the preferred technical implementation means is that the cooling temperature in step C is 4°C to 10°C.

[0031] Since the meat residue enzymatic hydrolysate is rich in nutrients and is prone to breed other microorganisms, the loss of nutrients is minimized under conditions that are convenient for storage. The preferred technical implementation method is to further include a step D, and the process conditions of this step are as follows:

[0032] D. Spray-dried powder preparation

[0033] The filtrate obtained in step C is spray-dried to prepare a spray-dried powder, and the spray-drying conditions are: the spray-drying temperature is 120°C to 130°C, the air inlet temperature is 75°C to 85°C, the air outlet temperature is 50°C to 60°C, and the injection port speed is 8 to 9 rpm.

[0034] In order to verify the technical effect achieved by the present invention, the applicant conducted the following tests and experiments on the meat residue enzymatic hydrolyzate prepared by the present invention.

[0035] 1. Ingredient Testing

[0036] The applicant sent the meat residue enzymatic hydrolyzate prepared by the present invention to Qingdao Zhengxin Testing and Analysis Co., Ltd. for component testing, and the test results are shown in Table 1:

[0037] Table 1 Component test results

[0038] Test items Detection basis Test results Free nitrogen, g / 100g Spectrophotometry 0.008 Total nitrogen, g / 100g GB5009.5-2016 0.96 Energy, KJ / 100g GB28050-2011 102 Protein, g / 100g GB5009.5-2016 First Law 5.99 Fat, g / 100g GB5009.5-2016 Second Law 0.1 Carbohydrate, g / 100g GB28050-2011 0.2 Sodium, mg / 100g GB5009.91-2017 378

[0039] It can be seen from the test results in Table 1 that the meat residue hydrolyzate prepared by the method of the present invention is rich in total nitrogen and protein content and can be used as a nitrogen source for microbial fermentation.

[0040] Second, the meat residue hydrolyzate spray-dried powder prepared by the present invention was used as a nitrogen source, and peptone was used as a nitrogen source control for fermentation with Bacillus subtilis, whose Latin name is Bacillus subtilis and whose deposit number is CGMCC No. 11625, to prepare neutral protease JW-3. The specific results are shown in Table 2 and Table 3. The above-mentioned biological material was submitted to the depository institution for deposit in November 2015 by the applicant, and is currently in a state that the public can know about it.

[0041] Table 2 Effect of different addition amounts of meat residue hydrolyzate dry powder on enzyme activity

[0042] Addition amount 0.1g 0.5g 1.0g 1.5g 2.0g Enzyme activity (U / mL) 695 961 1240 997 495

[0043] Table 3 Effect of peptone as nitrogen source on enzyme activity

[0044] Addition amount 0.1g 0.5g 1.0g 1.5g 2.0g Enzyme activity (U / mL) 734 940 1025 914 867

[0045] It can be seen from Tables 2 and 3 that when the addition amount of meat residue hydrolyzate spray-dried powder is 0.5g, 1.0g and 1.5g, the enzyme activity of the prepared neutral protease JW-3 is higher than the enzyme activity of the neutral protease JW-3 prepared when the addition amount of peptone is 0.5g, 1.0g and 1.5g.

[0046] The substantial features and significant technical advances of the present invention are:

[0047] 1. The present invention adopts a process of high temperature and high pressure hydrolysis in coordination with compound enzyme hydrolysis to prepare meat residue from leather making into meat residue hydrolysate. The test results show that the meat residue hydrolysate is rich in total nitrogen and protein and can be used as a nitrogen source for microbial fermentation.

[0048] 2. The present invention removes fat from meat residue enzymatic hydrolysate to prepare spray-dried powder, which is then used as a nitrogen source for microbial fermentation. According to the applicant's test, the powder is used in the fermentation production of neutral protease JW-3 prepared by Bacillus subtilis, whose Latin name is Bacillus subtilis and whose preservation number is CGMCC No.11625. Firstly, the environmental pollution problem caused by the difficulty in handling leather residue is solved; secondly, the leather residue solid waste is provided with a secondary utilization method, while the utilization value is improved; thirdly, compared with peptone as a nitrogen source, the neutral protease JW-3 prepared by the spray-dried powder prepared in the present invention when an effective amount is added is higher than that of the control group using peptone as a nitrogen source.

[0049] 3. Meat residue enzymatic hydrolysate spray-dried powder is rich in protein and can be used not only as a nitrogen source for microbial fermentation, but also added to feed for the breeding industry. The fat produced during the preparation process can be further purified and made into a fatting agent for use in the leather making process. DETAILED DESCRIPTION

[0050] The following is a further description of the embodiments of the present invention, but it is not intended to limit the present invention. The protection scope of the present invention shall be subject to the contents of the claims, and any equivalent technical means replaced according to the description shall not depart from the protection scope of the present invention.

[0051] Example 1

[0052] The method for resource utilization of leather residue solid waste includes pretreatment and enzymatic hydrolysis; the process steps and process conditions are as follows:

[0053] A. Pretreatment

[0054] A1. Cleaning

[0055] Weigh 500 g of leather residue, add 500 ml of water, place in a shake bottle, and shake at 100 rpm for 150 minutes;

[0056] A2. High temperature and high pressure hydrolysis

[0057] Add 200 ml of water to the leather residue after A1 washing and heat at 121°C and 1.013×10 5 Heating at 1000 Pa for 2 hours;

[0058] B. Enzymatic hydrolysis

[0059] The meat residue hydrolyzate treated in step A2 was cooled to room temperature, and enzyme preparations were added in the following amounts: 0.3 g / L alkaline protease, 0.1 g / L alkaline lipase, and 0.1 g / L trypsin; the insoluble matter was filtered out after enzymolysis at 35°C and 100 rpm for 2 hours;

[0060] C. Fat removal

[0061] The meat residue enzymatic hydrolyzate after filtering out the insoluble matter is cooled at low temperature, and after the liquid and lipid parts are separated, the fat layer is removed, the insoluble matter is filtered out, and the filtrate is collected.

[0062] D. Spray-dried powder preparation

[0063] The filtrate obtained in step C is spray-dried to prepare a spray-dried powder, and the spray-drying conditions are: a spray-drying temperature of 120° C., an air inlet temperature of 75° C., an air outlet temperature of 50° C., and an inlet speed of 8 rpm.

[0064] The shaking in step A1 is performed by changing the water every 30 to 40 minutes, and the washing is performed 5 to 6 times in total.

[0065] The enzymatic activity of alkaline protease in step B is 200,000 U / g, the optimum temperature is 40°C to 50°C, and the optimum pH is 8.0; the enzymatic activity of alkaline lipase is 500 U / g, the optimum temperature is 35°C to 40°C, and the optimum pH is 7.5; the enzymatic activity of trypsin is 30,000 U / g, the optimum temperature is 35°C to 45°C, and the optimum pH is 7.5 to 8.0.

[0066] The cooling temperature in step C is 4°C.

[0067] Example 2

[0068] The method for resource utilization of leather residue solid waste includes pretreatment and enzymatic hydrolysis; the process steps and process conditions are as follows:

[0069] A. Pretreatment

[0070] A1. Cleaning

[0071] Weigh 600 g of leather residue, add 600 ml of water, place in a shake bottle, and shake at 150 rpm for 240 minutes;

[0072] A2. High temperature and high pressure hydrolysis

[0073] Add 300 ml of water to the leather residue after A1 washing and heat at 121°C and 1.013×10 5 Heating at 1000 Pa for 3 hours;

[0074] B. Enzymatic hydrolysis

[0075] The meat residue hydrolyzate treated in step A2 was cooled to room temperature, and enzyme preparations were added in the following amounts: 0.4 g / L alkaline protease, 0.2 g / L alkaline lipase, and 0.2 g / L trypsin; the insoluble matter was filtered out after enzymolysis at 37° C. and 150 rpm for 3 hours;

[0076] C. Fat removal

[0077] The meat residue enzymatic hydrolyzate after filtering out the insoluble matter is cooled at low temperature, and after the liquid and lipid parts are separated, the fat layer is removed, the insoluble matter is filtered out, and the filtrate is collected.

[0078] D. Spray-dried powder preparation

[0079] The filtrate obtained in step C was spray-dried to prepare a spray-dried powder, and the spray-drying conditions were as follows: the spray-drying temperature was 130° C., the air inlet temperature was 85° C., the air outlet temperature was 60° C., and the injection port speed was 9 rpm.

[0080] The shaking in step A1 is performed by changing the water every 30 to 40 minutes, and the washing is performed 5 to 6 times in total.

[0081] The enzymatic activity of alkaline protease in step B is 200,000 U / g, the optimum temperature is 40°C to 50°C, and the optimum pH is 8.0; the enzymatic activity of alkaline lipase is 500 U / g, the optimum temperature is 35°C to 40°C, and the optimum pH is 7.5; the enzymatic activity of trypsin is 30,000 U / g, the optimum temperature is 35°C to 45°C, and the optimum pH is 7.5 to 8.0.

[0082] The cooling temperature in step C is 10°C.

[0083] Example 3

[0084] The method for resource utilization of leather residue solid waste includes pretreatment and enzymatic hydrolysis; the process steps and process conditions are as follows:

[0085] A. Pretreatment

[0086] A1. Cleaning

[0087] Weigh 550 g of leather residue, add 550 ml of water, place in a shake bottle, and shake at 130 rpm for 200 minutes;

[0088] A2. High temperature and high pressure hydrolysis

[0089] Add 250 ml of water to the leather residue after A1 washing and heat at 121°C and 1.013×10 5 Heating at 1000 Pa for 2.5 hours;

[0090] B. Enzymatic hydrolysis

[0091] The meat residue hydrolyzate treated in step A2 was cooled to room temperature, and enzyme preparations were added in the following amounts: 0.35 g / L alkaline protease, 0.15 g / L alkaline lipase, and 0.15 g / L trypsin; the insoluble matter was filtered out after enzymolysis at 36° C. and 130 rpm for 2.5 hours;

[0092] C. Fat removal

[0093] The meat residue enzymatic hydrolyzate after filtering out the insoluble matter is cooled at low temperature, and after the liquid and lipid parts are separated, the fat layer is removed, the insoluble matter is filtered out, and the filtrate is collected.

[0094] D. Spray-dried powder preparation

[0095] The filtrate obtained in step C is spray-dried to prepare a spray-dried powder, and the spray-drying conditions are as follows: the spray-drying temperature is 125° C., the air inlet temperature is 80° C., the air outlet temperature is 55° C., and the injection port speed is 8 rpm.

[0096] The shaking in step A1 is performed by changing the water every 30 to 40 minutes, and the washing is performed 5 to 6 times in total.

[0097] The enzymatic activity of alkaline protease in step B is 200,000 U / g, the optimum temperature is 40°C to 50°C, and the optimum pH is 8.0; the enzymatic activity of alkaline lipase is 500 U / g, the optimum temperature is 35°C to 40°C, and the optimum pH is 7.5; the enzymatic activity of trypsin is 30,000 U / g, the optimum temperature is 35°C to 45°C, and the optimum pH is 7.5 to 8.0.

[0098] The cooling temperature in step C is 7°C.

[0099] Example 4

[0100] The method for resource utilization of leather residue solid waste includes pretreatment and enzymatic hydrolysis; the process steps and process conditions are as follows:

[0101] A. Pretreatment

[0102] A1. Cleaning

[0103] Weigh 520 g of leather residue, add 520 ml of water, place in a shake bottle, and shake at 110 rpm for 180 minutes;

[0104] A2. High temperature and high pressure hydrolysis

[0105] Add 220 ml of water to the leather residue after A1 washing and heat at 121°C and 1.013×10 5 Heating at 1.500 Pa for 2.2 hours;

[0106] B. Enzymatic hydrolysis

[0107] The meat residue hydrolyzate treated in step A2 was cooled to room temperature, and enzyme preparations were added in the following amounts: 0.32 g / L alkaline protease, 0.12 g / L alkaline lipase, and 0.12 g / L trypsin; the insoluble matter was filtered out after enzymolysis at 37° C. and 110 rpm for 2.2 hours;

[0108] C. Fat removal

[0109] The meat residue enzymatic hydrolyzate after filtering out the insoluble matter is cooled at low temperature, and after the liquid and lipid parts are separated, the fat layer is removed, the insoluble matter is filtered out, and the filtrate is collected.

[0110] D. Spray-dried powder preparation

[0111] The filtrate obtained in step C is spray-dried to prepare a spray-dried powder, and the spray-drying conditions are: a spray-drying temperature of 122° C., an air inlet temperature of 72° C., an air outlet temperature of 52° C., and an inlet speed of 8 rpm.

[0112] The shaking in step A1 is performed by changing the water every 30 to 40 minutes, and the washing is performed 5 to 6 times in total.

[0113] The enzymatic activity of alkaline protease in step B is 200,000 U / g, the optimum temperature is 40°C to 50°C, and the optimum pH is 8.0; the enzymatic activity of alkaline lipase is 500 U / g, the optimum temperature is 35°C to 40°C, and the optimum pH is 7.5; the enzymatic activity of trypsin is 30,000 U / g, the optimum temperature is 35°C to 45°C, and the optimum pH is 7.5 to 8.0.

[0114] The cooling temperature in step C is 5°C.

[0115] Example 5

[0116] The method for resource utilization of leather residue solid waste includes pretreatment and enzymatic hydrolysis; the process steps and process conditions are as follows:

[0117] A. Pretreatment

[0118] A1. Cleaning

[0119] Weigh 580 g of leather residue, add 580 ml of water, place in a shake bottle, and shake at 140 rpm for 220 minutes;

[0120] A2. High temperature and high pressure hydrolysis

[0121] Add 280 ml of water to the leather residue after A1 washing and heat at 121°C and 1.013×10 5 Heating at 1.500 Pa for 2.8 hours;

[0122] B. Enzymatic hydrolysis

[0123] The meat residue hydrolyzate treated in step A2 was cooled to room temperature, and enzyme preparations were added in the following amounts: 0.38 g / L alkaline protease, 0.18 g / L alkaline lipase, and 0.18 g / L trypsin; the insoluble matter was filtered out after enzymolysis at 35° C. and 140 rpm for 2.8 hours;

[0124] C. Fat removal

[0125] The meat residue enzymatic hydrolyzate after filtering out the insoluble matter is cooled at low temperature, and after the liquid and lipid parts are separated, the fat layer is removed, the insoluble matter is filtered out, and the filtrate is collected.

[0126] D. Spray-dried powder preparation

[0127] The filtrate obtained in step C was spray-dried to prepare a spray-dried powder, and the spray-drying conditions were as follows: the spray-drying temperature was 128° C., the air inlet temperature was 82° C., the air outlet temperature was 58° C., and the injection port speed was 9 rpm.

[0128] The shaking in step A1 is performed by changing the water every 30 to 40 minutes, and the washing is performed 5 to 6 times in total.

[0129] The enzymatic activity of alkaline protease in step B is 200,000 U / g, the optimum temperature is 40°C to 50°C, and the optimum pH is 8.0; the enzymatic activity of alkaline lipase is 500 U / g, the optimum temperature is 35°C to 40°C, and the optimum pH is 7.5; the enzymatic activity of trypsin is 30,000 U / g, the optimum temperature is 35°C to 45°C, and the optimum pH is 7.5 to 8.0.

[0130] The cooling temperature in step C is 8°C.

Claims

1. A method for resource utilization of leather residue solid waste, comprising pretreatment and enzymolysis; characterized in that The process steps and process conditions are as follows: A. Pretreatment A1. Cleaning Weigh 500 g to 600 g of leather residue, add 500 ml to 600 ml of water, place in a shaking bottle, and shake at a speed of 100 to 150 rpm for 150 to 240 minutes; A2. High temperature hydrolysis Add 200ml to 300ml of water to the leather residue after A1 washing, and heat at 121℃ and 1.013×10 5 Heating at 1000 rpm for 2 to 3 hours; B. Enzymatic hydrolysis The meat residue hydrolyzate treated in step A2 is cooled to room temperature, and enzyme preparations are added in the following amounts: alkaline protease 0.3-0.4 g / L, alkaline lipase 0.1-0.2 g / L, and trypsin 0.1-0.2 g / L; after enzymolysis for 2-3 hours at 35°C-37°C and 100-150 rpm, insoluble matter is filtered out. The enzymatic activity of alkaline protease in step B is 200,000 U / g, the optimum temperature is 40°C-50°C, and the optimum pH is 8.0; the enzymatic activity of alkaline lipase is 500 U / g, the optimum temperature is 35°C-40°C, and the optimum pH is 7.5; the enzymatic activity of trypsin is 30,000 U / g, the optimum temperature is 35°C-45°C, and the optimum pH is 7.5-8.0; C. Fat removal The meat residue enzymatic hydrolyzate after filtering out the insoluble matter is cooled at low temperature, and after the liquid and lipid parts are separated, the fat layer is removed, the insoluble matter is filtered out, and the filtrate is collected; D. Spray-dried powder preparation The filtrate obtained in step C is spray-dried to prepare a spray-dried powder, and the spray-drying conditions are: the spray-drying temperature is 120°C to 130°C, the air inlet temperature is 75°C to 85°C, the air outlet temperature is 50°C to 60°C, and the injection port speed is 8 to 9 rpm.

2. The method for resource utilization of leather residue solid waste according to claim 1, characterized in that The shaking in step A1 is performed by changing the water every 30 to 40 minutes, and the washing is performed 5 to 6 times in total.

3. The method for resource utilization of leather residue solid waste according to claim 1, characterized in that The cooling temperature in step C is 4°C to 10°C.