A method for resource utilization of potato starch wastewater

Abstract

The present invention relates to the technical field of wastewater resource utilization, and specifically to a method for resource utilization of potato starch wastewater. The method filters out large particle impurities from wastewater, then adds a stabilizer and introduces it into a heated stirring tank for heating. After it reaches a certain temperature, a flocculant is added to the wastewater and stirred evenly. At this time, the protein in the wastewater will quickly condense, and the condensed potato starch wastewater is extracted, and a protective agent is added after centrifugal dehydration. After low-temperature drying, a product rich in potato protein can be obtained. The method of the present invention does not require the addition of acid and alkali reagents. The stabilizer, flocculant and protective agent used have multiple physiological functions such as biodegradability and non-toxicity, and can be used as food additives. Therefore, the protein recovered by this method is non-toxic and harmless. At the same time, compared with traditional recovery methods, the method of the present invention greatly shortens the recovery time, and the obtained product tastes better, is more nutritious, and is widely applicable.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater resource utilization, and in particular to a method for resource utilization of potato starch wastewater. Background Art

[0002] Wastewater discharged during potato starch production primarily consists of rinsing wastewater, protein solution (cell sap), and starch extraction wastewater. Rinse wastewater primarily consists of potato peelings and surface sediment, with a COD concentration of approximately 500 mg / L. Protein solution and starch extraction wastewater primarily consist of organic matter such as protein and starch, with COD concentrations exceeding 10,000 mg / L. Protein solution, generated during the starch milk concentration and separation process, accounts for approximately 10% to 20% of the total discharge volume and is the primary source of pollution in potato starch wastewater. Direct discharge of this wastewater into natural water bodies can severely pollute the water, causing eutrophication and hypoxia. This can manifest as decreased pH, increased mineralization, ammonia nitrogen, and sulfide concentrations, large amounts of white foam floating on the water surface, and increased turbidity. This can harm aquatic animals, leading to mass fish kills. Direct discharge into soil can cause environmental problems such as soil compaction and foul odors.

[0003] At present, the methods for treating potato starch wastewater include natural sedimentation, foam separation, ultrafiltration, isoelectric precipitation, flocculation, etc. The natural sedimentation method takes a long time and requires a large number of sedimentation tanks, which is time-consuming and labor-intensive, and has not been widely used in practice; although the foam separation method uses a mechanical process that will not cause secondary pollution to the starch waste liquid, it is easily affected by various factors such as solute properties, temperature, pH, ventilation volume, and other factors, and other substances will be introduced during the foam formation process to reduce the purity of the protein; the protein recovered by the ultrafiltration method has good purity, taste, functional properties, etc., but the ultrafiltration equipment is expensive, the construction cost is high, and it is prone to pollutant blockage problems, and the operating cost is high, so it is not suitable for use by small and medium-sized enterprises; the isoelectric precipitation method recovers protein with high purity, but requires the addition of a large amount of acid or alkali, which is costly; the flocculation method is simple to operate and has low operating costs, and has good application prospects for the treatment of potato starch wastewater.

[0004] The existing flocculation process is limited by process conditions and generally has the problems of long time consumption, low potato protein extraction rate, and large-scale denaturation of potato protein. At the same time, the products obtained are generally of low quality and poor applicability. In addition, the treated wastewater still contains a large amount of potato protein, and the subsequent wastewater treatment process still has difficulties. Therefore, a method for resource utilization of potato starch wastewater that can quickly and efficiently recover protein from potato starch wastewater and obtain high-quality products is an urgent problem to be solved. Summary of the Invention

[0005] The object of the present invention is to provide a method for resource utilization of potato starch wastewater in view of the deficiencies in the above-mentioned prior art, which can quickly and efficiently recover protein in potato starch wastewater, obtain high-quality products, reduce the risk of environmental pollution, and realize resource utilization of potato starch wastewater.

[0006] To achieve the above object, the present invention adopts the following technical solution: a method for resource utilization of potato starch wastewater, characterized in that it comprises the following steps:

[0007] 1) the potato starch wastewater from which impurities are removed is introduced into a heated and stirred tank, a stabilizer is added under stirring and the temperature is evenly increased;

[0008] 2) maintaining stirring and adding a certain amount of flocculant to the heated potato starch wastewater;

[0009] 3) centrifuging the potato starch wastewater after adding the flocculant;

[0010] 4) adding a protective agent to the precipitate obtained after centrifugation;

[0011] 5) The precipitate with the protective agent added is subjected to low-temperature drying to obtain a finished product rich in potato protein.

[0012] Furthermore, in the step 1), the stirring intensity is 40-60 r / min, and the potato starch wastewater is uniformly heated to 60-70°C.

[0013] Furthermore, in the step 1), the stabilizer is a fish gelatin solution with a mass fraction of 0.1%.

[0014] Furthermore, in the step 1), the mass ratio of potato starch wastewater to fish gelatin solution is 3000-5000:1.

[0015] Furthermore, in the step 2), the flocculant is a carboxymethyl cellulose solution with a mass fraction of 0.5%.

[0016] Furthermore, in the step 2), the mass ratio of potato starch wastewater to carboxymethyl cellulose solution is 1000-2000:1.

[0017] Furthermore, after adding the flocculant in step 3), stirring is continued for 1 to 3 minutes, and then the potato starch wastewater after adding the flocculant is centrifuged by a horizontal screw centrifuge.

[0018] Furthermore, in the step 4), the protective agent is a 10% glucose solution.

[0019] Furthermore, in the step 4), the mass ratio of the glucose solution to the obtained precipitate is 0.5 to 1:1.

[0020] Furthermore, in the step 5), the drying temperature is 40-50° C., the drying time is 10-12 hours, and the moisture content is no more than 3%.

[0021] Beneficial effects of the present invention:

[0022] 1. Rapid recovery of protein from potato starch wastewater is achieved by increasing the heating temperature, and by adding stabilizers, potato protein is prevented from deteriorating, which is beneficial to quickly obtain high-quality potato protein;

[0023] 2. The potato protein is coagulated by a flocculant and then centrifuged in a decanter centrifuge to achieve rapid recovery of the potato protein;

[0024] 3. By adding protective agents, on the one hand, the drying stability is improved to avoid the deterioration of potato protein, and on the other hand, the drying time can be effectively shortened, making the treatment of potato starch wastewater more efficient;

[0025] 4. Stabilizers, flocculants and protective agents all have multiple physiological functions such as biodegradability and non-toxicity, and can be used as food additives. Therefore, the protein recovered by this method is non-toxic and harmless, and the resulting product has a better taste, richer nutrition and is widely applicable. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the process flow of the present invention;

[0027] Figure 2 It is a flowchart of the process of the present invention.

[0028] The names corresponding to the marks in the figure are:

[0029] 1. Filter; 2. Heating and stirring tank; 3. Agitator; 4. Flocculant storage tank; 5. Dosing pump A; 6. Stabilizer storage tank; 7. Dosing pump B; 8. Transfer pump; 9. Horizontal screw centrifuge; 10. Protective agent storage tank; 11. Dosing pump C; 12. Atomizer. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0031] The potato starch wastewater generated during the potato starch production process is filtered through the filter 1 and introduced into the heating stirring tank 2. A stabilizer is added to the heating stirring tank 2 through the dosing pump B7. During the process, the stabilizer is a 0.1% fish gelatin solution. The mass ratio of potato starch wastewater to fish gelatin solution is 3000-5000:1. The potato starch wastewater is heated under stirring conditions. During the operation, the stirring intensity is 40-60r / min. The potato starch wastewater is heated to 60-70°C. After the heating is completed, the carboxymethyl cellulose solution in the flocculant storage tank 4 is added to the heating stirring tank 2 through the dosing pump A5 and stirred. The method comprises the steps of: uniformly stirring the potato starch wastewater, stirring the potato starch wastewater, and centrifuging the potato protein precipitate through a delivery pump 8 to obtain a potato protein precipitate; the stirring time during the process is 1 to 3 minutes; the mass fraction of the carboxymethyl cellulose solution is 0.5%; and the mass ratio of the potato starch wastewater to the carboxymethyl cellulose solution is 1000 to 2000:1. After the stirring is completed, the potato starch wastewater is pumped into a horizontal screw centrifuge 9 through a delivery pump 8 for centrifugation to obtain a potato protein precipitate; and a protective agent is sprayed into the potato protein precipitate through an atomizer 12. During the process, the protective agent is a 10% glucose solution, and the mass ratio of the added protective agent to the potato protein precipitate is 0.5 to 1:1. Then, after low-temperature drying, a finished product rich in potato protein can be obtained, and the moisture content of the potato protein finished product must be reduced to no more than 3%.

[0032] The principle of the present invention is:

[0033] The potato starch wastewater generated during the potato starch production process contains impurities such as mud and sand because the wastewater contains a portion of flushing wastewater. It needs to be filtered out by filter 1 to remove the impurities. The potato starch wastewater with impurities removed is stirred and heated in the heating and stirring tank 2. The heating can increase the flocculation rate of potato protein, which has a positive effect on subsequent flocculation and precipitation. However, in order to avoid large-scale denaturation of potato protein, a stabilizer is added during the process, wherein the stabilizer is fish gelatin solution. The addition of the stabilizer can increase the heating temperature. The heating temperature during the process is 60-70°C, which can effectively accelerate the flocculation of potato protein and will not cause denaturation of potato protein.

[0034] After heating, adding carboxymethyl cellulose solution can make potato protein flocculate quickly. During the flocculation process, the potato protein is condensed into agglomerates, which is beneficial to the subsequent centrifugal separation operation, can improve the efficiency of centrifugation and reduce the centrifugation time, and also make the potato protein separation more thorough. Centrifugation uses a horizontal screw centrifuge to separate the viscous potato protein precipitate. The obtained potato protein precipitate is sprayed with a protective agent through an atomizer, and then low-temperature drying is performed to obtain a potato protein product. The addition of the protective agent during the process can reduce the risk of protein denaturation and aggregation and increase the stability of protein particles, effectively reducing the drying time. In actual production, low-temperature drying for 10 to 12 hours can reduce the moisture content of the potato protein to no more than 3%, making the treatment of potato protein wastewater more efficient and having a better treatment effect.

[0035] Example 1

[0036] 0.1% fish gelatin solution was added to potato starch wastewater under stirring at a ratio of 3000:1 and a stirring intensity of 60 r / min. The potato starch wastewater was heated to 70°C, and 0.5% carboxymethyl cellulose solution was added to the wastewater at a ratio of 1000:1. The stirring was continued for 3 minutes. The mixed solution was pumped into a horizontal screw centrifuge for centrifugal treatment. Then, 10% glucose solution was added to the obtained potato protein precipitate at a ratio of 1:1. The product was dried at a low temperature of 50°C for 10 hours to obtain a potato protein-rich product with a water content of 2.6%. Finally, the potato protein extraction rate was 85.7%.

[0037] Potato protein extraction rate Calculated by the following formula:

[0038]

[0039] Where:

[0040] M is the total mass of the batch of potato starch wastewater;

[0041] ω is the mass fraction of potato protein in potato starch wastewater;

[0042] m1 is the mass of extracted potato protein;

[0043] m2 is the mass of the added fish peptide solution;

[0044] m3 is the mass of the added carboxymethyl cellulose solution;

[0045] m4 is the mass of glucose solution added;

[0046] γ is the moisture content of potato protein product.

[0047] In the above formula, the mass fraction of potato protein in potato starch wastewater ω is the actual measurement.

[0048] Example 2

[0049] A 0.1% fish gelatin solution was added to potato starch wastewater under stirring at a ratio of 5000:1 and a stirring intensity of 40 r / min. The potato starch wastewater was heated to 60°C, and a 0.5% carboxymethyl cellulose solution was added to the wastewater at a ratio of 2000:1. The stirring was continued for 1 minute. The mixed solution was pumped into a horizontal screw centrifuge for centrifugal treatment. Then, a 10% glucose solution was added to the obtained potato protein precipitate at a ratio of 0.5:1. The product was dried at a low temperature of 40°C for 12 hours to obtain a potato protein-rich product with a moisture content of 2.9%. Finally, the potato protein extraction rate was 81.4%.

[0050] The potato protein extraction rate was calculated as in Example 1.

[0051] Example 3

[0052] 0.1% fish gelatin solution was added to potato starch wastewater under stirring at a ratio of 4000:1 and a stirring intensity of 50 r / min. The potato starch wastewater was heated to 65°C, and 0.5% carboxymethyl cellulose solution was added to the wastewater at a ratio of 1500:1. The stirring was continued for 2 minutes. The mixed solution was pumped into a horizontal screw centrifuge for centrifugal treatment. Then, 10% glucose solution was added to the obtained potato protein precipitate at a ratio of 0.8:1. The product was low-temperature dried at 45°C for 11 hours to obtain a potato protein-rich product with a moisture content of 2.8%. Finally, the potato protein extraction rate was 83.1%.

[0053] The potato protein extraction rate was calculated as in Example 1.

[0054] Comparative Example 1

[0055] The potato starch wastewater is not heated, and 0.5% carboxymethyl cellulose solution is added to the wastewater at a ratio of 1000:1. After the addition, the mixture is stirred at 60 r / min for 3 minutes to cause a flocculation reaction between the wastewater and the carboxymethyl cellulose solution. The mixed solution is conveyed to a horizontal screw centrifuge for centrifugal separation to obtain a potato protein precipitate. The potato protein precipitate is low-temperature dried at 50°C for 15 hours to obtain a potato protein-rich product with a moisture content of 2.8%. Finally, the potato protein extraction rate is 46.3%.

[0056] The potato protein extraction rate is calculated as in Example 1, wherein m2 and m4 are zero.

[0057] Comparative Example 2

[0058] The potato starch wastewater is uniformly heated to 70°C, and a 0.5% carboxymethyl cellulose solution is added to the wastewater at a ratio of 1000:1. After the addition, the mixture is rapidly stirred at 60r / min for 3 minutes to cause a flocculation reaction between the wastewater and the carboxymethyl cellulose solution. The mixed solution is transported to a horizontal screw centrifuge for centrifugal separation to obtain a potato protein precipitate. The potato protein precipitate is low-temperature dried at 50°C for 18 hours to obtain a potato protein-rich product with a moisture content of 2.7%. Finally, the potato protein extraction rate is 85.4%. Liquid chromatography detection shows that the potato protein is denatured by about 40%.

[0059] The potato protein extraction rate is calculated as in Example 1, wherein m2 and m4 are zero.

[0060] Comparative Example 3

[0061] A 0.1% fish gelatin solution was added to potato starch wastewater under stirring at a ratio of 3000:1 and a stirring intensity of 60 r / min. The potato starch wastewater was heated to 70°C, and a 0.5% carboxymethyl cellulose solution was added to the wastewater at a ratio of 1000:1. The stirring was continued for 3 minutes. The mixed solution was pumped into a horizontal screw centrifuge for centrifugal treatment, and then the obtained potato protein precipitate was low-temperature dried at 50°C for 18 hours to obtain a potato protein-rich product with a water content of 2.7%. Finally, the potato protein extraction rate was 85.8%. Liquid chromatography detection showed that the potato protein was denatured by about 15%.

[0062] The potato protein extraction rate was calculated as in Example 1, where m4 was zero.

[0063] Comparative Example 4

[0064] Compare with the Chinese invention patent "A method for recovering glycoprotein from potato starch processing wastewater", authorization announcement number: CN 103864888 B.

[0065] The potato starch wastewater was not heated, and 1% chitosan solution was added to the wastewater at a ratio of 1:5. The pH was adjusted to 6.5 with a pH regulator. After stirring and standing, the supernatant was taken to calculate the potato protein recovery rate. The potato protein was then separated through a complex and precipitated as chitosan. The supernatant was vacuum freeze-dried at 20Pa and -50°C for 50 hours to obtain a potato protein product. Finally, the potato protein extraction rate was 43% and the purity was 84%.

[0066] In this comparative example, heating was not used. At the same time, a large amount of chitosan solution was added to improve the recovery rate. Although the chitosan solution was recovered, the recovery process was relatively complicated, which increased the production cost. In addition, the low-temperature drying time was long and the energy consumption was high, which brought difficulties to industrial application.

[0067] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, any technical solution that is the same or similar to that of the present application falls within the scope of protection of the present invention.

Claims

1. A method for resource utilization of potato starch wastewater, characterized in that: The following steps are involved: 1) The potato starch wastewater from which impurities have been removed is introduced into a heated stirring tank, stabilizer is added under stirring, and the temperature is uniformly raised; The potato starch wastewater is uniformly heated to 60-70°C; the stabilizer is fish gelatin solution; the stirring intensity is 40-60 r / min; the mass fraction of the fish gelatin solution is 0.1%, and the mass ratio of potato starch wastewater to fish gelatin solution is 3000-5000:1; 2) Maintain stirring and add a certain amount of flocculant to the heated potato starch wastewater; The flocculant is carboxymethyl cellulose solution; the mass fraction of the carboxymethyl cellulose solution is 0.5%, and the mass ratio of potato starch wastewater to the carboxymethyl cellulose solution is 1000-2000:1; 3) Centrifugal treatment of potato starch wastewater after adding flocculant; 4) Add protective agent to the precipitate obtained after centrifugation; The protective agent is glucose solution; the mass fraction of the glucose solution is 10%, and the mass ratio of the glucose solution to the obtained precipitate is 0.5~1:1; 5) Low-temperature drying the precipitate to which the protective agent has been added to obtain a finished product rich in potato protein; the drying temperature is 40-50° C., the drying time is 10-12 hours, and the moisture content is no more than 3%.

2. A potato starch wastewater resource utilization method according to claim 1, characterized in that: In the step 3), stirring is continued for 1 to 3 minutes after the flocculant is added, and then the potato starch wastewater after the flocculant is added is centrifuged by a horizontal screw centrifuge.

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