Method for cleaning mussel shells and its application

Abstract

The application discloses a kind of river mussel shell depth scale removal method and application thereof, comprising the following steps: 1) the river mussel shell to be treated is completely immersed in cleaning solution constant temperature soaking;Cleaning solution includes: biological enzyme and water, the biological enzyme is selected from at least two kinds of alkaline protease, lipase and cellulase, and the concentration of biological enzyme is 0.05%-0.15% by mass volume ratio;2) the river mussel shell of soaking is completed is ultrasonic cleaned, and super micro bubble is synchronously imported to carry out collaborative treatment;3) the river mussel shell after cleaning is rinsed repeatedly, and after draining, low-temperature drying is obtained, to obtain the river mussel shell after processing.This scheme adopts cleaning solution containing biological enzyme to combine ultrasonic cleaning and micro-bubble collaborative descaling, black scale removal rate can reach more than 95%, the calcium retention rate of river mussel shell is not less than 98%, does not damage the original calcium structure of river mussel shell, the river mussel shell after processing meets the safety access requirements of feed-grade raw materials, and wastewater COD is as low as 290mg / L, green and environmental protection.

Description

Technical Field

[0001] This invention relates to the field of freshwater mussel shell cleaning technology, and in particular to a method for deep cleaning of freshwater mussel shells and its application. Background Technology

[0002] Freshwater mussel shells are a major byproduct of the aquaculture and seafood processing industries. Their main component is calcium carbonate, which can be widely processed into calcium additives for livestock and poultry feed, calcium supplements for aquaculture, and calcium-based fillers for soil amendment, among other resource-based products. The surface and crevices of natural freshwater mussel shells are typically covered with a thick layer of black, complex grime, rich in heavy metal residues, aquatic microbial secretions, and parasite metabolic waste.

[0003] Current freshwater mussel shell cleaning processes still have many technical shortcomings: 1. Traditional methods using strong acids and alkalis for cleaning easily corrode the calcium carbonate structure on the surface of the mussel shell, causing a large loss of effective calcium components. At the same time, chemical residues are serious, the cleaning wastewater has high COD concentration and excessive heavy metals, the subsequent environmental treatment costs are high, and the produced materials are difficult to meet feed-grade safety standards; 2. Using only high-pressure water washing or ordinary water soaking can only remove surface dust and impurities, but cannot remove stubborn dirt deep in the crevices, and the organic matter and heavy metal residues are difficult to meet the standards; 3. Simple ultrasonic cleaning has low descaling efficiency and high energy consumption, and is not suitable for industrial continuous batch production. Summary of the Invention

[0004] Therefore, it is necessary to provide a green, mild, high-calcium-retaining, and low-pollution deep cleaning method for freshwater mussel shells and its application, which addresses the above problems and ensures that the treated freshwater mussel shells meet the safety standards for feed-grade raw materials.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for deep cleaning of freshwater mussel shells includes the following steps:

[0007] 1) Completely immerse the freshwater mussel shells to be treated in the cleaning solution at a constant temperature; the cleaning solution includes: biological enzymes and water, wherein the biological enzymes are selected from at least two of alkaline protease, lipase and cellulase, and the concentration of the biological enzymes is 0.05%-0.15% by mass-volume ratio;

[0008] 2) The soaked freshwater mussel shells are ultrasonically cleaned, and microbubbles are introduced simultaneously for synergistic treatment;

[0009] 3) Rinse the cleaned clam shells multiple times, drain them, and dry them at a low temperature to obtain the processed clam shells.

[0010] Preferably, in step 1), the bioenzymes include, by mass percentage: alkaline protease: 40%-75%; lipase: 0%-35%; cellulase: 0%-40%.

[0011] Preferably, in step 1), the pH of the cleaning solution is 6.5-8.5.

[0012] Preferably, in step 1), the soaking temperature of the freshwater mussel shells to be treated is 25℃-40℃, and the soaking time is 30min-60min.

[0013] Preferably, in step 2), the ultrasonic frequency of ultrasonic cleaning is 20kHz-40kHz; the average particle size of the microbubbles is 50nm-200nm; and the synergistic processing time is 10min-20min.

[0014] Preferably, in step 3), the cleaned clam shells are rinsed with clean soft water 2-3 times.

[0015] Preferably, in step 3), the drying temperature is 45℃-50℃.

[0016] Application of freshwater mussel shells treated with the above-described deep cleaning method in livestock and poultry feed, aquaculture feed, and soil conditioner.

[0017] The present invention, by adopting the above technical solution, has the following beneficial effects:

[0018] 1. This invention uses a cleaning solution containing biological enzymes to replace traditional strong acids and alkalis. No strong corrosive agents are added throughout the process. It is biodegradable and leaves no harmful residues. The calcium retention rate of the freshwater mussel shells is not less than 98%, and the original calcium structure of the freshwater mussel shells is not damaged. The treated freshwater mussel shells meet the safety access requirements for feed-grade raw materials. The COD of the wastewater is as low as 290mg / L, making it green and environmentally friendly.

[0019] 2. This invention uses a cleaning solution containing biological enzymes combined with ultrasonic cleaning and microbubble synergistic descaling, achieving a black scale removal rate of over 95%, thoroughly removing deep-seated dirt from crevices, and controlling and meeting the standards for heavy metal and organic residues. Detailed Implementation

[0020] The embodiments of this application are described in detail below. The described embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] In this invention, except for the components specifically described for synthesis, all other components and reagents involved are conventional commercially available products or can be obtained through conventional technical means in the art. Unless otherwise stated, the materials, methods, and embodiments of this invention are exemplary only and not limiting.

[0022] A method for deep cleaning of freshwater mussel shells includes the following steps:

[0023] 1) Completely immerse the freshwater mussel shells to be treated in the cleaning solution at a constant temperature; the cleaning solution includes: biological enzymes and water, wherein the biological enzymes are selected from at least two of alkaline protease, lipase and cellulase, and the concentration of the biological enzymes is 0.05%-0.15% by mass-volume ratio;

[0024] 2) The soaked freshwater mussel shells are ultrasonically cleaned, and microbubbles are introduced simultaneously for synergistic treatment;

[0025] 3) Rinse the cleaned clam shells multiple times, drain them, and dry them at a low temperature to obtain the processed clam shells.

[0026] The freshwater mussel shells to be processed can first have residual soft tissue and attached large pieces of mud and sand removed. Qualitative / quantitative analysis of the black dirt on the surface of the shells is then performed. If plant fiber impurities such as algae are detected in the dirt, cellulase is added to the biological enzyme; otherwise, cellulase is not added. The mussel shells mentioned include, but are not limited to, the shells of the triangular sail mussel and the pleated crown mussel.

[0027] Specifically, in step 1), the bioenzymes, by mass percentage, include: alkaline protease: 40%-75%; lipase: 0%-35%; and cellulase: 0%-40%. In this solution, alkaline protease primarily decomposes proteinaceous organic matter such as collagen and mucin in the dirt; lipase assists in decomposing lipid components in the dirt, improving the permeability of the cleaning solution; and cellulase removes plant fiber impurities from the dirt, thereby gently softening and decomposing stubborn black dirt without corroding the calcium carbonate matrix.

[0028] Preferably, in step 1), the pH of the cleaning solution is 6.5-8.5.

[0029] Preferably, in step 1), the soaking temperature of the freshwater mussel shells to be treated is 25℃-40℃, and the soaking time is 30min-60min. The soaking temperature and soaking time can be selected according to the degree of calcification of the dirt on the freshwater mussel shells. For example, when the degree of calcification of the dirt on the freshwater mussel shells is high, a lower soaking temperature and a longer soaking time can be selected, so that the enzymes can continuously penetrate into the dirt to decompose it.

[0030] Preferably, in step 2), the ultrasonic cleaning uses an ultrasonic frequency of 20kHz-40kHz; the average particle size of the microbubbles is 50nm-200nm; and the synergistic processing time is 10min-20min. In this scheme, the instantaneous impact force generated by ultrasonic cavitation and bubble bursting is used to precisely peel off the fully softened calcification layer and flush away residual dirt deep in the crevices.

[0031] Preferably, in step 3), the cleaned freshwater mussel shells are rinsed 2-3 times using clean, soft water. This prevents calcium loss and secondary adhesion of surface dirt.

[0032] Preferably, in step 3), the drying temperature is 45℃-50℃. This can prevent the mussel shells from developing micro-cracks due to rapid heating.

[0033] An application of freshwater mussel shells treated with the deep cleaning method described above in livestock and poultry feed, aquaculture feed, and soil conditioner. Specifically, the treated freshwater mussel shells can be used as calcium additives in livestock and poultry feed, calcium supplements in aquaculture, and calcium-based fillers in soil conditioners.

[0034] The effects of the technical solution of this application will be further illustrated below through several specific application examples.

[0035] Example 1:

[0036] A method for deep cleaning of freshwater mussel shells includes the following steps:

[0037] 1) Take the shells of the pleated crown mussels that have been used for pearl farming for a long time and have calcified black dirt and parasitic algae residue on the shell surface. Remove the remaining soft tissue and large pieces of mud and sand inside the shell, take samples for testing, and determine that the dirt is mainly composed of calcium carbonate-organic complex crystals, heavy metals (copper, zinc) and algal metabolites.

[0038] 2) Preparation of cleaning solution: The bio-enzymes, by mass percentage, include: 60% alkaline protease and 40% cellulase. The CAS number of alkaline protease is 9014-01-1, and the CAS number of cellulase is 9012-54-8. Prepare a cleaning solution with a bio-enzyme concentration of 0.1% by mass volume (i.e., add 0.1g of mixed enzyme powder to every 100ml of water). Using a pH meter, add 0.1mol / L dilute hydrochloric acid solution dropwise while continuously stirring and adjusting the pH to 6.8. Completely immerse the freshwater mussel shells in the cleaning solution and soak them at a constant temperature of 30℃ for 60 minutes.

[0039] 3) Transfer the soaked mussel shells to an ultrasonic cleaning tank, set the ultrasonic frequency to 28kHz, and simultaneously start the microbubble generator to inject microbubbles with an average particle size of 80nm into the water. The co-processing time is 10 minutes.

[0040] 4) Rinse the cleaned clam shells three times with clean, soft water to remove the detached dirt and debris. After draining, slowly dry them under 45°C circulating air to obtain the processed clam shells.

[0041] Collect the waste liquid from steps 2) to 4).

[0042] Example 2:

[0043] A method for deep cleaning of freshwater mussel shells includes the following steps:

[0044] 1) Take discarded triangular sail mussel shells from a seafood processing plant, remove large pieces of mud and sand, and test the composition of the black dirt on the shell surface. It was confirmed to be a compound pollution of heavy metals and organic metabolites.

[0045] 2) Preparation of cleaning solution: The biological enzymes, by mass percentage, include: 66.6% alkaline protease and 33.3% lipase; among which, the alkaline protease is CAS number 9014-01-1; the lipase is CAS number 9001-62-1. Prepare a cleaning solution with a mass-volume ratio of 0.1% (i.e., add 0.1g of mixed enzyme powder to every 100ml of water). Using a pH meter, add 0.1mol / L dilute hydrochloric acid solution dropwise while continuously stirring to adjust the pH to 8.5; completely immerse the freshwater mussel shells in the cleaning solution and soak at a constant temperature of 35℃ for 45 minutes.

[0046] 3) Transfer the soaked mussel shells to an ultrasonic cleaning tank, set the ultrasonic frequency to 40kHz, and simultaneously start the microbubble generator to inject microbubbles with an average particle size of 100nm into the water. The co-processing time is 15 minutes.

[0047] 4) Rinse the cleaned clam shells three times with clean, soft water to remove the dirt and debris. After draining, slowly dry them under 50°C circulating air to obtain the processed clam shells.

[0048] Collect the waste liquid from steps 2) to 4).

[0049] Example 3:

[0050] A method for deep cleaning of freshwater mussel shells includes the following steps:

[0051] 1) Take discarded triangular sail mussel shells from a seafood processing plant, remove large pieces of mud and sand, and test the composition of the black dirt on the shell surface. It was confirmed to be a compound pollution of heavy metals and organic metabolites.

[0052] 2) Preparation of cleaning solution: The biological enzymes, by mass percentage, include: 70% alkaline protease, 20% lipase, and 10% cellulase; among which, the alkaline protease is CAS number 9014-01-1; the lipase is CAS number 9001-62-1; and the cellulase is CAS number 9012-54-8. Prepare a cleaning solution with a mass-volume ratio of 0.1% (i.e., add 0.1g of mixed enzyme powder to every 100ml of water). Using a pH meter, add 0.1mol / L dilute hydrochloric acid solution dropwise while continuously stirring to adjust the pH to 9.0. Completely immerse the freshwater mussel shells in the cleaning solution and soak them at a constant temperature of 45℃ for 120 minutes.

[0053] 3) Transfer the soaked mussel shells to an ultrasonic cleaning tank, set the ultrasonic frequency to 32kHz, and simultaneously start the microbubble generator to inject microbubbles with an average particle size of 80nm into the water. The co-processing time is 20 minutes.

[0054] 4) Rinse the cleaned clam shells three times with clean, soft water to remove the dirt and debris. After draining, slowly dry them under 50°C circulating air to obtain the processed clam shells.

[0055] Collect the waste liquid from steps 2) to 4).

[0056] Comparative Example 1:

[0057] 1) Take discarded triangular sail mussel shells from a seafood processing plant and remove large pieces of mud and sand;

[0058] 2) Completely immerse the freshwater mussel shells in 5% dilute hydrochloric acid and soak them at a constant temperature of 22°C for 45 minutes;

[0059] 3) Rinse the cleaned clam shells three times with clean, soft water to remove the detached dirt and debris. After draining, slowly dry them under 50°C circulating air to obtain the processed clam shells.

[0060] Collect the waste liquid from steps 2) to 3).

[0061] Comparative Example 2:

[0062] 1) Take discarded triangular sail mussel shells from a seafood processing plant and remove large pieces of mud and sand;

[0063] 2) Immerse the clam shells in clean water in the ultrasonic cleaning tank, set the ultrasonic frequency to 40kHz, and simultaneously start the microbubble generator to inject microbubbles with an average particle size of 100nm into the water. The co-processing time is 15 minutes.

[0064] 3) Rinse the cleaned clam shells three times with clean, soft water to remove the detached dirt and debris. After draining, slowly dry them under 50°C circulating air to obtain the processed clam shells.

[0065] Collect the waste liquid from steps 2) to 3).

[0066] Comparative Example 3:

[0067] 1) Take discarded triangular sail mussel shells from a seafood processing plant and remove large pieces of mud and sand;

[0068] 2) Preparation of cleaning solution: The solution is made by mixing acidic protease and lipase at a mass percentage ratio of 2:1. Prepare a cleaning solution with a mass-volume ratio of 0.1% (i.e., add 0.1g of mixed enzyme powder to every 100ml of water). Using a pH meter, add 0.1mol / L dilute hydrochloric acid solution dropwise while stirring continuously to adjust the pH to 3.5. Completely immerse the freshwater mussel shells in the cleaning solution and soak them at a constant temperature of 35℃ for 45 minutes.

[0069] 3) Rinse the cleaned clam shells three times with clean, soft water to remove the detached dirt and debris. After draining, slowly dry them under 50°C circulating air to obtain the processed clam shells.

[0070] Collect the waste liquid from steps 2) to 3).

[0071] The treated freshwater mussel shells and waste liquid from Examples 1-2 and Comparative Examples 1-3 were tested.

[0072] The detection method is as follows:

[0073] Cleanliness: Inspect the surface appearance of the freshwater mussel shells.

[0074] Black sludge removal rate: Quantitative detection was performed using image area analysis: The shell surfaces of the mussels were photographed before and after treatment, and the percentage of black sludge coverage area on the shell surface was statistically analyzed using image analysis software. The black sludge removal rate was calculated using the following formula: Black sludge removal rate = [(Black sludge coverage rate before treatment - Black sludge coverage rate after treatment) ÷ Black sludge coverage rate before treatment] × 100% black sludge.

[0075] Calcium retention rate: The calcium content of freshwater mussel shells is determined according to the "Determination of Calcium in Feed" (GB / T 6436-2018). Calcium retention rate = (Calcium content of treated mussel shells ÷ Initial calcium content of original mussel shells) × 100% to calculate the retention rate.

[0076] Heavy metal residues: The copper and zinc residues on the surface of freshwater mussel shells were tested according to the standard "Determination of Calcium, Copper, Iron, Magnesium, Manganese, Potassium, Sodium and Zinc Content in Feed by Atomic Absorption Spectrometry" (GB / T 13885-2017). The standard limit for feed-grade raw materials is ≤20mg / kg, that is, the total residue of copper and zinc is ≤20mg / kg.

[0077] Waste liquid COD index: determined according to the "Determination of Chemical Oxygen Demand in Water - Dichromate Method" (HJ 828-2017).

[0078] The test results of the treated freshwater mussel shells in Examples 1-3 and Comparative Examples 1-3 are shown in Table 1 below:

[0079] Group cleanliness Black stain removal rate Calcium retention rate Heavy metal residue (mg / kg) Example 1 The pearly layer on the shell is clear, and there is no black grime or algae residue in the crevices. 95.2% 98.5% 11.8 Example 2 The shell surface was free of black residue, and the crevices were clean. 96.5% 98.8% 9.4 Example 3 The shell surface is bright and white, the nacre layer is intact and translucent, and there is no black dirt, organic matter or algae residue in the crevices or deep textures, and there is no whitening or corrosion of the shell. 97.8% 99.1% 7.9 Comparative Example 1 The shell is white, locally corroded, and black grime remains in the crevices. 78.0% 85% 17.3 Comparative Example 2 There is a lot of black grime residue on the shell surface, and obvious organic residue in the deep crevices. 65.3% 99.0% 33.8 Comparative Example 3 There are residues of detached material on the shell surface, and a small amount of organic residue deep in the crevices. 82.1% 98.2% 27.6

[0080] The detection results of the waste liquid in Examples 1-3 and Comparative Examples 1-3 are shown in Table 2 below:

[0081] Group COD value (mg / L) Example 1 290 Example 2 320 Example 3 275 Comparative Example 1 850 Comparative Example 2 480 Comparative Example 3 380

[0082] The results show that, as demonstrated in Examples 1, 2, and Comparative Example 1, the enzyme-containing cleaning solution provided in this scheme, replacing traditional strong acid and strong alkali cleaning solutions, significantly improves the calcium retention rate of freshwater mussel shells and greatly reduces the COD index of the waste liquid. The treated freshwater mussel shells meet the safety access requirements for feed-grade raw materials. This process has significant advantages in protecting the freshwater mussel shell matrix and in terms of environmental protection. Examples 2 and Comparative Examples 2-3 show that using an enzyme-containing cleaning solution combined with ultrasonic cleaning and microbubble synergistic descaling can achieve a black scale removal rate of over 95%, thoroughly removing deep-seated dirt from crevices, improving cleaning efficiency, and completely removing dirt.

[0083] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, alterations, deletions of some features, additions of features, or recombinations of features to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the innovative principles of the present invention shall still fall within the scope of the technical solutions of the present invention.

Claims

1. A method for deep cleaning of freshwater mussel shells, characterized in that, Includes the following steps: 1) Completely immerse the freshwater mussel shells to be treated in a cleaning solution at a constant temperature; the cleaning solution includes: biological enzymes and water, wherein the biological enzymes are selected from at least two of alkaline protease, lipase and cellulase, and the concentration of the biological enzymes is 0.05%-0.15% by mass-volume ratio; 2) The soaked clam shells are ultrasonically cleaned, and microbubbles are introduced simultaneously for synergistic treatment; 3) Rinse the cleaned clam shells multiple times, drain them, and dry them at a low temperature to obtain the processed clam shells.

2. The method for deep cleaning of freshwater mussel shells according to claim 1, characterized in that, In step 1), the biological enzymes, by mass percentage, include: alkaline protease: 40%-75%; lipase: 0%-35%; cellulase: 0%-40%.

3. The method for deep cleaning of freshwater mussel shells according to claim 1, characterized in that, In step 1), the pH of the cleaning solution is 6.5-8.

5.

4. The method for deep cleaning of freshwater mussel shells according to claim 1, characterized in that, In step 1), the soaking temperature of the freshwater mussel shells to be treated is 25℃-40℃, and the soaking time is 30min-60min.

5. The method for deep cleaning of freshwater mussel shells according to claim 1, characterized in that, In step 2), the ultrasonic cleaning uses an ultrasonic frequency of 20kHz-40kHz; the average particle size of the microbubbles is 50nm-200nm; and the co-processing time is 10min-20min.

6. The method for deep cleaning of freshwater mussel shells according to claim 1, characterized in that, In step 3), the cleaned clam shells are rinsed 2-3 times with clean soft water.

7. The method for deep cleaning of freshwater mussel shells according to claim 1, characterized in that, In step 3), the drying temperature is 45℃-50℃.

8. The application of freshwater mussel shells treated with the deep cleaning method for freshwater mussel shells as described in any one of claims 1-7 in livestock and poultry feed, aquaculture feed, and soil conditioner.