Composite biological carbon source for sewage treatment and preparation method thereof

Abstract

The invention discloses a composite biological carbon source for sewage treatment and a preparation method thereof, and relates to the technical field of biological sewage treatment. The invention discloses a composite biological carbon source for sewage treatment, which is prepared by the following steps: by taking waste by-products in a fermentation process as basic raw materials, decomposing high-molecular organic matters in the waste by-products into small-molecular organic matters which are easily absorbed and utilized by organisms through hydrolase, and carrying out solid-liquid separation to obtain a carbon source mother solution; adding sodium acetate and easily degradable organic matters in a proper proportion to obtain the composite biological carbon source; the ratio of the waste by-product to the sodium acetate to the easily degradable organic matter in the fermentation process is (70-100): (0-10): (0-20) by taking CODCr as the concentration ratio. The composite biological carbon source provided by the invention has the advantages of easily available raw materials, simple components, simple preparation method and greatly reduced production cost; the composite biological carbon source has the advantages of strong adaptability, long-term effect, high denitrification rate and denitrification effect.

Description

Technical Field

[0001] The present invention relates to the technical field of biological sewage treatment, and particularly relates to a composite biological carbon source for sewage treatment and a preparation method thereof. Background Art

[0002] At present, the main ways for existing sewage treatment plants in China to remove NH4 + -N and TN are based on the principles of biological nitrification and denitrification. Among them, the denitrification process needs to provide an organic carbon source as the electron donor for denitrifying bacteria to carry out denitrification, that is, to denitrify 1 mg of NO3 - -N, the amount of organic carbon source converted into BOD5 is 2.86 mg; at the same time, the growth of microorganisms themselves also requires a carbon source, and efficient denitrification can be achieved only when the actual B / N ratio is above 4.0; in addition, biological phosphorus removal also requires a carbon source. Therefore, the amount of organic carbon source required for simultaneous nitrogen and phosphorus removal is even higher. Therefore, the types and concentrations of organic matters in sewage directly affect the denitrification rate and nitrogen removal effect. However, affected by the existing urban drainage system, the influent of municipal sewage treatment plants in China generally shows the characteristics of low COD Cr and low C / N. The lack of organic carbon source directly leads to insufficient biological denitrification process, which in turn affects the up-to-standard discharge of TN in the effluent of sewage treatment plants, and is more serious when the water temperature is low. Therefore, in order to ensure the up-to-standard discharge of sewage, sewage treatment plants often need to supplement organic carbon source additionally.

[0003] In the prior art, the externally added organic carbon sources are mainly divided into two categories: solid carbon sources and liquid carbon sources. Among them, the commonly used externally added carbon sources in sewage treatment plants are mainly liquid carbon sources, and the currently commonly used ones include methanol, ethanol, acetic acid, sodium acetate, glucose, etc. These carbon source products have fixed properties, relevant standards, high solubility, good biodegradability, are easily absorbed and utilized by microorganisms, and have high denitrification rates and denitrification effects. However, due to the high consumption rate of these carbon sources, it leads to a large amount of carbon source consumption and large dosing amount, resulting in high reagent costs, large sludge production, and large carbon dioxide emissions; moreover, a single carbon source cannot meet the diverse needs of various microorganisms. Long-term dosing of a single carbon source is likely to lead to a decrease in the abundance of system strains and reduce the shock resistance of the system. In this regard, a composite carbon source containing two or more organic compounds that are easily utilized by microorganisms can improve the deficiencies of a single carbon source, but it does not achieve the purpose of reducing costs. To reduce the carbon source dosing cost, people have not only developed a precise carbon source dosing system, but also studied and tried non-standard carbon sources such as high-concentration organic wastewater, sludge hydrolysis liquid, and biomass carbon source in the food and fermentation industries. This type of carbon source is equivalent to the resource utilization of waste, with low dosing cost, and contains a variety of easily degradable organic matters that can be utilized by microorganisms, a large abundance of bacterial flora, and a high denitrification rate. However, there are also problems such as unfixed product properties, high transportation costs, difficult long-term storage, and the presence of interfering substances (such as toxic and harmful substances, substances containing nitrogen and phosphorus, substances containing difficult-to-biodegrade organic matters, and bacteria).

[0004] In summary, although there are many types of carbon sources currently, common carbon sources still have deficiencies in terms of cost, denitrification rate, specific consumption, sludge production, safety, etc. There is an urgent need to develop efficient, economical, safe, and convenient organic carbon source products suitable for dosing and use in sewage treatment plants in China. Summary of the Invention

[0005] The purpose of the present invention is to provide a composite biological carbon source required for denitrification and nitrogen removal in the process of sewage biochemical treatment, which has easily available raw materials, simple composition, and a simple preparation method, greatly reducing the production cost; this composite biological carbon source has strong adaptability, long-acting property, high denitrification rate, and denitrification effect.

[0006] To achieve the purpose of the present invention, the present invention provides a composite biological carbon source for sewage treatment, which uses waste by-products in the fermentation process as the basic raw material, and decomposes high-molecular organic matter in the waste by-products into small-molecular organic matter that is easily absorbed and utilized by organisms through composite biological enzymes. After solid-liquid separation, a carbon source mother liquor is obtained, and then an appropriate proportion of sodium acetate and easily degradable organic matter is added to obtain the composite biological carbon source.

[0007] The mass ratio of the carbon source mother liquor, sodium acetate, and easily degradable organic matter is (70 - 100):(0 - 10):(0 - 20).

[0008] The present invention also provides a preparation method for a composite biological carbon source for sewage treatment, which specifically includes the following steps:

[0009] S1. Centrifugally separate the solid and liquid of the waste by-products in the fermentation process to obtain a supernatant and solid substances;

[0010] S2. Add water to the above solid substances to form a slurry-like mixture, add composite biological enzymes to the mixture, mix evenly, perform aerobic fermentation, and after the fermentation is completed, perform centrifugal solid-liquid separation to obtain a separation liquid;

[0011] S3. Mix the above supernatant and separation liquid to obtain a carbon source mother liquor (i.e., the waste extract obtained after treating the waste by-products generated in the fermentation process), and then add sodium acetate and easily degradable organic matter to the carbon source mother liquor, and stir well to obtain the composite biological carbon source.

[0012] Further, in the step S1, the rotation speed of the centrifugal separation is 5000 - 8000 r / min, the temperature is 4 - 30 °C, and the time is 5 - 15 min.

[0013] Further, in the step S2, the mass of the added water is 1.5 - 3 times the mass of the supernatant.

[0014] Further, in the step S2, the addition amount of the composite bio-enzyme in the mixed solution is 1 to 15 g / L.

[0015] Further, the composite bio-enzyme is a combination of any two or more of dextranase, β-mannanase, neutral protease or papain.

[0016] In the present invention, dextranase is an endonuclease, and the preferred dosage is 0.02-0.05% of the dry weight of the material, which can effectively decompose β-glucan in the endosperm cell walls of wheat and cereal plants, producing oligosaccharides and glucose with 3 to 5 glucose units, facilitating the increase of saccharification concentration and the total amount of α-amino acids, while reducing the viscosity of the mixed solution, improving the solid-liquid separation performance, and increasing the dissolution rate of organic matter; the functions of papain and neutral protease are to degrade proteins in the mixed solution into small molecule peptides and amino acids to supply carbon sources for yeast and promote fermentation, and their preferred dosages are both 1 to 4 mg / kg; β-mannanase belongs to the hemicellulase class and is used to hydrolyze mannan oligosaccharides and mannopolysaccharides (including mannan, galactomannan, glucomannan, etc.) containing β-1,4-mannosidic bonds into oligosaccharides such as mannan oligosaccharides. At the same time, through the effect of degrading the cell wall, nutrients such as starch and protein in plant cells are released, improving the material conversion efficiency, and its preferred dosage is 5 to 10 mg / kg.

[0017] Further, in the step S2, the temperature of the aerobic fermentation is 25 to 50 °C, the stirring rate is 60 to 120 r / min, and the fermentation time is 6 to 48 h.

[0018] Further, in the step S3, the mass ratio of the carbon source mother liquor, sodium acetate and easily degradable organic matter is (70 to 100):(0 to 10):(0 to 20).

[0019] Further, the easily degradable organic matter is any one or more of ethylene glycol, methanol, ethanol, propanol, propylene glycol, glycerol, formic acid, propionic acid, butyric acid, valeric acid, citric acid, glucose or starch.

[0020] The present invention has achieved the following beneficial effects:

[0021] 1. The composite bio-carbon source of the present invention has the characteristics of good adaptability and can be quickly absorbed and utilized by denitrifying bacteria in activated sludge. When the carbon source of the present invention is added to a sewage treatment plant, after the denitrifying bacteria are domesticated and adapted, a higher denitrification rate and denitrification effect will be shown.

[0022] 2. The ΔCOD / ΔTN value of the composite biological carbon source of the present invention is lower than that of carbon sources such as sodium acetate, acetic acid, and glucose. To remove a unit of TN or nitrate, under the same conditions, the dosage of the composite biological carbon source of the present invention is about 29.8% lower than that of the acetic acid carbon source. Therefore, using the carbon source of the present invention can save operating costs and the generation amount of excess sludge.

[0023] 3. All raw materials used in the composite biological carbon source of the present invention are safe and non-toxic. When meeting the carbon source demand in the denitrification process of the anoxic tank, the remaining carbon source can also be rapidly degraded by heterotrophic bacteria in the aerobic tank, and the effluent COD Cr complies with the national emission standards. The product is safe and non-toxic and will not cause environmental ecological poisoning and personnel poisoning.

[0024] 4. Since the COD of the composite biological carbon source of the present invention Cr is mainly composed of waste by-products in the production process of the fermentation industry, the production cost of the carbon source is greatly reduced, and it has a cost advantage compared with common carbon sources such as sodium acetate, acetic acid, ethylene glycol, glycerol, and glucose on the market.

[0025] 5. The production process of the composite biological carbon source of the present invention is simple. The carbon source finished product is non-flammable, non-corrosive, and easy to store and transport; at the same time, it has good low-temperature performance, is not prone to crystallization and solidification, and is suitable for use under low-temperature conditions.

[0026] The performance indexes of the product prepared by the present invention are as follows: specific gravity is 1.0 - 1.25, pH value is 6 - 8, viscosity is 50 - 80, solubility is 100%, freezing point is -20 - -40 °C, and COD Cr value is 160,000 - 1,000,000. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a graph showing the hourly change of TN when different carbon sources are added to a sewage treatment plant in an embodiment of the present invention;

[0028] Figure 2 is a graph showing the hourly change of NO3 - -N when different carbon sources are added to a sewage treatment plant in an embodiment of the present invention;

[0029] Figure 3 is a graph showing the hourly change of COD when different carbon sources are added to a sewage treatment plant in an embodiment of the present invention; Cr hourly change graph;

[0030] Figure 4 is a graph showing the hourly change of TN when different carbon sources are added to a sewage treatment plant in an embodiment of the present invention;

[0031] Figure 5 is a graph showing the hourly change of COD when different carbon sources are added to a sewage treatment plant in an embodiment of the present invention; Cr hourly change graph;

[0032] Figure 6 It is a graph showing the hourly variation of the effluent TN when different carbon sources are added for denitrification in a certain landfill leachate treatment plant according to an embodiment of the present invention;

[0033] Figure 7 It is a graph showing the hourly variation of the nitrate nitrogen in the effluent when different carbon sources are added for denitrification in a certain landfill leachate treatment plant according to an embodiment of the present invention. Specific embodiments

[0034] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. All the features disclosed in this specification, or all the steps in any method or process disclosed, can be combined in any way, except for mutually exclusive features and / or steps.

[0035] The present invention will be further specifically described below with reference to specific embodiments.

[0036] Embodiment 1 The preparation method of the composite biological carbon source for sewage treatment in this embodiment is as follows:

[0037] (1) First, the waste yeast liquid (containing substances such as ethanol, various amino acids, vitamins, yeast, starch, polysaccharides, and monosaccharides) in the beer production process is subjected to solid-liquid separation (centrifugal separation: rotation speed 5000 r / min, temperature 4 °C, separation for 5 min), to obtain a supernatant and solid substances.

[0038] (2) The solid substances are mixed with water (the amount of added water is 2 times the mass of the supernatant) to form a slurry. A composite biological enzyme is added to the mixed solution (wherein, glucanase is 0.04% of the dry weight of the material; papain is 2 mg / kg; the dosage of β-mannanase is 5 mg / kg) and mixed evenly, and fermentation is carried out at 30 °C (stirring speed 100 r / min). After 12 h of fermentation, centrifugal solid-liquid separation is carried out (rotation speed 5000 r / min, temperature 4 °C, separation for 5 min), to obtain a separation liquid.

[0039] (3) The supernatant and the separation liquid are mixed to obtain a carbon source mother liquor. Ethylene glycol is added to the carbon source mother liquor, and the mass ratio of their COD Cr is 74:26 (that is, 5.6 mL of ethylene glycol is added to 100 mL of the carbon source mother liquor). Subsequently, it is fully stirred to obtain the 2# biological carbon source (COD Cr value is 300,000 mg / L).

[0040] (4) The supernatant and the separation liquid are mixed to obtain a carbon source mother liquor. Sodium acetate is added to the carbon source mother liquor, and the mass ratio of their COD Cr is 74:26 (that is, 10 g of anhydrous sodium acetate is added to 100 mL of the carbon source mother liquor). Subsequently, it is fully stirred to obtain the 3# biological carbon source (COD CrThe value is 300,000 mg / L).

[0041] Take the mixed liquor at the end of the aerobic tank in the sewage treatment plant for beaker bench-scale tests. The COD of the mixed liquor Cr is 15 mg / L, TN is 13.32 mg / L, ammonia nitrogen is 4.74 mg / L, nitrate nitrogen is 6.93 mg / L, and the sludge concentration SS is 6,243 mg / L. The stirring is carried out by a magnetic stirrer. Control the stirring speed to maintain the DO of the beaker mixed liquor below 0.5 mg / L and ensure that the sludge can be evenly mixed.

[0042] Use the 2# bio-carbon source, 3# bio-carbon source prepared in the above Example 1, the sodium acetate carbon source currently used in a certain sewage treatment plant, and glucose to compare the denitrification and nitrogen removal effects of the mixed liquor coming out of the end of the anoxic-aerobic tank. The test results are as Figures 1-3 shown in Table 1.

[0043] Table 1 Comparison of denitrification and nitrogen removal effects of different carbon sources

[0044]

[0045]

[0046] Note: (1) The calculation of Y N is based on Figure 1 the numerical values of the straight-line segment; (2) Glucose is food grade.

[0047] As Figures 1-3 shown, when adding the sodium acetate carbon source, food-grade glucose, 2# bio-carbon source, and 3# bio-carbon source in a certain sewage treatment plant, the hourly changes of TN, NO3 - -N and COD Cr are shown.

[0048] From Table 1 above and Figures 1-3 the data, it can be seen that the sodium acetate carbon source and food-grade glucose used in a certain sewage treatment plant have similar denitrification rates and denitrification rates, and their corresponding Y N is 0.368 mg TN / g SS.h; the denitrification rates and denitrification rates of the sodium acetate carbon source and food-grade glucose carbon source are both lower than those of the composite bio-carbon source of the present invention. Among them, the denitrification rate and denitrification rate of the 3# bio-carbon source are as high as 1.861 mg TN / (g SS.h) and 1.682 mg NO3 - -N / (g SS.h), and NO3 - -N also drops from 4.74 mg / L to 0 mg / L within 0.5 h. The above data show that although the composite bio-carbon source of the present invention is used for the first time, it can be absorbed and utilized by the denitrifying bacteria in the activated sludge and exhibits high denitrification rates and denitrification effects, indicating that the composite bio-carbon source of the present invention has good adaptability.

[0049] As can be seen from the data in Table 1, in terms of the carbon source unit consumption ΔCOD / ΔTN value, the amount of carbon source required to remove unit TN: glucose > #3 biological carbon source of the present invention > #2 biological carbon source of the present invention > sodium acetate. Among them, the dosage of the #2 biological carbon source and the #3 biological carbon source of the present invention is lower than that of glucose and is close to that of sodium acetate.

[0050] Considering the comprehensive denitrification rate and carbon source unit consumption, the #3 biological carbon source of the present invention has good performance and can replace the currently used sodium acetate carbon source to save the operation cost.

[0051] Example 2

[0052] The preparation method of the composite biological carbon source for sewage treatment in this example is as follows:

[0053] (1) First, perform solid-liquid separation (centrifugal separation: rotation speed 5000 r / min, temperature 4 °C, separation for 5 min) on the waste yeast liquid (containing substances such as ethanol, various amino acids, vitamins, yeast, starch, polysaccharides, and monosaccharides) in the beer production process to obtain the supernatant and solid substances.

[0054] (2) Mix the solid substances with water (the amount of added water is 2 times the mass of the supernatant) to form a slurry. Add a composite biological enzyme (the problem here is the same as in Example 1) to the mixture (wherein, glucanase is 0.05% of the dry weight of the material; papain is 4 mg / kg; the dosage of β-mannanase is 2 mg / kg) and mix evenly. Perform aerobic fermentation at 40 °C (stirring speed 100 r / min). After 8 h, perform centrifugal solid-liquid separation (rotation speed 6000 r / min, temperature 4 °C, separation for 5 min) to obtain the separation liquid.

[0055] (3) Mix the supernatant and the separation liquid to obtain the carbon source mother liquor. Add ethylene glycol and sodium acetate to the carbon source mother liquor. The COD mass ratio of the three is 73:26:1 (that is, add 5.5 mL of ethylene glycol and 3.8 g of anhydrous sodium acetate to 100 mL of the mixed solution 1). Then stir well to obtain the #4 biological carbon source (300,000 mg / L COD Cr equivalent). Cr

[0056] A certain sewage treatment plant currently uses sodium acetate as the carbon source for denitrification, and the COD equivalent is about 300,000 mg / L.

[0057] Take the effluent mixed liquor from the anaerobic tank of the fourth-stage students (mixed sludge concentration MLSS = 5054 mg / L, total nitrogen in the liquid phase = 7.45 mg / L, CODcr = 17 mg / L). Take the mixed liquor at the end of the aerobic tank of the biological reactor for beaker bench-scale tests. The stirring is carried out by a magnetic stirrer, controlling the stirring speed to maintain the DO of the beaker mixed liquor below 0.5 mg / L and ensuring that the sludge can be evenly mixed. Compare the denitrification and nitrogen removal effects of the biological carbon source No. 3 and biological carbon source No. 4 of the present invention with the sodium acetate carbon source currently used in a sewage treatment plant in Shanghai. The test results are shown in Table 2, Table 3 and Figures 4-5 as shown

[0058] Table 2 Performance test results of different carbon sources in a sewage treatment plant in Shanghai

[0059]

[0060] Table 3 Comparison of denitrification effects of different carbon sources in a sewage treatment plant

[0061]

[0062]

[0063] Note: (1) The calculation of Y N is based on the Figure 4 values of the straight-line segment; (2) The value of ΔCOD / ΔTN is calculated based on the corresponding values for 2 h

[0064] As Figure 4 and Figure 5 shown, it is the result of bench-scale denitrification tests with different carbon sources added to a sewage treatment plant

[0065] From the data in Table 2, Table 3 and Figures 4-5 it can be seen that the sodium acetate and acetic acid carbon sources currently used in a sewage treatment plant show relatively consistent carbon source consumption rates and specific denitrification carbon source consumptions. However, the denitrification rate of sodium acetate is 2.137 mg TN / g SS.h, which is higher than that of acetic acid (1.591 mg TN / g SS.h) and the finished carbon source of the present invention, but slightly lower than that of the biological carbon source No. 3 of the present invention, which is 2.176 mg TN / g SS.h. It can be seen that although sodium acetate has been used for a long time in this activated sludge and the sludge has adapted to sodium acetate, it shows a relatively high denitrification rate. However, the composite biological carbon source of the present invention can be immediately absorbed and utilized by the activated sludge and shows high denitrification rates and denitrification effects. Its denitrification rate is not lower than that of sodium acetate, indicating that the composite biological carbon source of the present invention has very good adaptability

[0066] From Table 2, Table 3 and Figures 4-5According to the data, the consumption rates of sodium acetate and acetic acid carbon sources are higher than those of the composite biological carbon source of the present invention. It can be seen that the biological carbon source No. 3 and biological carbon source No. 4 of the present invention have better long-term effectiveness. Since the anoxic tank is basically in the form of a plug-flow reactor structure, the COD in the influent Cr is often consumed completely at the front end of the anoxic tank and cannot meet the demand for carbon sources for full denitrification and nitrogen removal. The characteristic of the long-term effectiveness of the composite biological carbon source of the present invention is more suitable for the plug-flow biochemical tank of the sewage treatment plant, ensuring that there is an available carbon source throughout the anoxic tank (section) to achieve sufficient denitrification and nitrogen removal.

[0067] As can be seen from the data in Table 3, in terms of the carbon source unit consumption ΔCOD / ΔTN value, the ΔCOD / ΔTN values of the composite biological carbon source of the present invention are all lower than those of the sodium acetate carbon source and acetic acid carbon source currently used in the factory. This means that the dosage of the composite biological carbon source of the present invention for removing unit TN or nitrate is lower than that of the acetic acid carbon source. Among them, about 29.8% can be saved with the biological carbon source No. 3 of the present invention, and more carbon source dosage is expected to be saved with the biological carbon source No. 4 of the present invention.

[0068] Considering the comprehensive denitrification rate and carbon source unit consumption, both the biological carbon source No. 3 and biological carbon source No. 4 of the present invention have good performance and can replace the currently used sodium acetate carbon source to save the operation cost and reduce the production of excess sludge.

[0069] Example 3

[0070] The preparation method of the composite biological carbon source for sewage treatment and the biological denitrification effect in this example are as follows:

[0071] 3.1 Case of generating the biological carbon source of the present invention

[0072] (1) First, the waste yeast liquid (containing substances such as ethanol, various amino acids, vitamins, yeast, starch, polysaccharides, and monosaccharides) in the beer production process is subjected to solid-liquid separation (centrifugal separation: rotation speed 5000 r / min, temperature 4 °C, separation for 5 min) to obtain supernatant A and solid substance B.

[0073] (2) The solid substance B is mixed with water (the amount of added water is 2 times the mass of supernatant A) to form a slurry. A composite biological enzyme (0.1% of the dry weight of the material of glucanase; 3 mg / kg of papain) is added to the mixed liquid and mixed evenly. Fermentation is carried out at 30 °C (stirring speed 100 r / min). After 12 h, centrifugal solid-liquid separation is carried out (rotation speed 5000 r / min, temperature 4 °C, separation for 5 min) to obtain separation liquid C.

[0074] (3) The supernatant A and separation liquid C are mixed to obtain the carbon source mother liquor D. Crude glycerol is added to the carbon source mother liquor D (COD CrThe volume ratio of the two was 81:19 (i.e., 100 mL of carbon source mother solution D was added with 23.4 mL of crude glycerol), and then fully stirred to obtain 1# biological carbon source (350,000 mg / L COD Cr equivalent).

[0075] (4) Ethylene glycol was added to the carbon source mother liquor D, with the volume ratio of the two being 10.6:89.4 (i.e., 11.8 mL of ethylene glycol was added to 100 mL of carbon source mother liquor D), and then stirred thoroughly to obtain 5# biological carbon source (350,000 mg / L COD Cr equivalent).

[0076] (5) Add crude glycerol (COD Cr Equivalent to 820,000 mg / L) and rice soaking water (COD Cr The volume ratio of the three is 73:22:5 (i.e., 100 mL of carbon source mother solution D is added with 30.1 mL of crude glycerol and 6.8 mL of rice water), and then stirred thoroughly to obtain 6# biological carbon source (350,000 mg / L COD Cr equivalent).

[0077] 3.2 Application and effect cases of the biological carbon source of the present invention

[0078] This pilot test was conducted in a leachate treatment plant in Hangzhou, with the aim of investigating the denitrification performance of different biological carbon sources of the present invention and carbon sources currently used in sewage treatment plants under the same carbon source COD addition concentration. The denitrification activated sludge system used this time was taken from the mixed sludge at the end of the biochemical reaction section of the second plant. After adding about 46 mg / L of nitrate nitrogen (potassium nitrate solution), the indicators of the mixed solution were tested, as shown in Table 4. The types of carbon sources and COD used in this pilot test Cr The measured results are shown in Table 5. The amount of carbon source added is based on COD Cr The carbon source addition test was carried out at an equivalent of 300 mg / L to compare the denitrification and nitrogen removal effects of different carbon sources. The test and analysis results are shown in Tables 6-9 and Figures 6-7 shown.

[0079] Table 4 Denitrification mixed solution test results

[0080]

[0081] Note: * Nitrate nitrogen data are the test results of the laboratory of the present invention according to the national standard method.

[0082] Table 5 Test results of CODCr equivalent of experimental carbon source (Hach instrument)

[0083]

[0084] Table 6 Denitrification test effluent total nitrogen test results

[0085]

[0086] Note: The total nitrogen data are the measurement results using a Hach instrument. The total nitrogen at 0 h is based on the total nitrogen of the stock solution.

[0087] Table 7 CODcr test results of the effluent from the denitrification bench-scale test

[0088]

[0089]

[0090] Note: The COD at 0 h Cr is from the COD of the stock solution Cr plus the COD of the actually added carbon source Cr and is calculated based on the concentration.

[0091] Table 8 Nitrate nitrogen test results of the effluent from the denitrification bench-scale test

[0092]

[0093] Note: The nitrate nitrogen data are the test results of the laboratory of the present invention according to the national standard method. The nitrate nitrogen at 0 h is based on the nitrate nitrogen of the stock solution

[0094] Table 9 Comparison of denitrification and nitrogen removal effects of different carbon sources

[0095]

[0096] Note: (1) Since Figure 2 the straight-line segment of the denitrification curve is not obvious, the calculations of YN1 and YN2 are based on Figure 6 and Figure 7 and the average value is calculated for the first 4 hours. (2) The calculation of ΔCOD / ΔTN and the total nitrogen removal rate is based on the 18 h of the end point of this reaction, where ΔCOD is calculated according to the COD concentration of the added carbon source. (3) The total nitrogen removal rate and the nitrate nitrogen removal rate are calculated based on the 18 h of the end point of this reaction.

[0097] In this test, the mixed liquor at the end of the biochemical pool of the sewage treatment plant was obtained, with a COD Cr concentration of 392 mg / L. Through blank test comparison, it can be seen from Table 4, Table 5, Figure 6 and Figure 7 that as the reaction time extends, the total nitrogen concentration in the mixed liquor system remains basically unchanged, and the COD Cr of this part has little effect on denitrification and is basically COD that is not easily absorbed and utilized by microorganisms Cr .

[0098] From the denitrification rate Y in Table 9 N1It can be seen that the denitrification rate of Bio-carbon source No. 5 > Bio-carbon source No. 6 > Bio-carbon source No. 1 > glucose, and the denitrification rate of Bio-carbon source No. 5 is 220% higher than that of glucose. From the perspective of the denitrification rate Y N2 It can be seen that the denitrification rate of Bio-carbon source No. 5 > Bio-carbon source No. 1 ≈ Bio-carbon source No. 6 > glucose. Among them, the denitrification rate of Bio-carbon source No. 1 is 60% higher than that of glucose, the denitrification rate of Bio-carbon source No. 5 is 125% higher than that of glucose, and the denitrification rate of Bio-carbon source No. 6 is 53% higher than that of glucose. Therefore, the denitrification rate and denitrification rate of the three bio-carbon sources of the present invention in this small test are both higher than those of glucose currently used in the sewage treatment plant, and the denitrification performance of Bio-carbon source No. 5 is the best.

[0099] By analyzing the denitrification carbon source unit consumption of the four carbon sources, it can be known that Bio-carbon source No. 5 < Bio-carbon source No. 1 = Bio-carbon source No. 6 < glucose. Among them, the denitrification unit consumption of Bio-carbon source No. 1 and Bio-carbon source No. 6 of the present invention is reduced by 22.9% compared with that of glucose, while the denitrification unit consumption of Bio-carbon source No. 5 is reduced by 43.5% compared with that of glucose. Therefore, the denitrification carbon source unit consumption of the three bio-carbon sources of the present invention in this small test is lower than that of the currently used glucose carbon source, which means that the amount of the bio-carbon source of the present invention used to remove unit nitrate nitrogen (TN) is less than that of the glucose carbon source, thus saving the carbon source usage cost.

[0100] After 18 hours of reaction, the total nitrogen removal rates of the denitrification effluents of Bio-carbon source No. 1, Bio-carbon source No. 5, Bio-carbon source No. 6 and glucose of the present invention are 41.01%, 56.12%, 41.01% and 31.65% respectively, and the nitrate nitrogen removal rates are 55.52%, 71.20%, 51.57% and 37.36% respectively. The three bio-carbon sources of the present invention perform better, and the removal rate of Bio-carbon source No. 5 corresponding to the denitrification reaction is the highest.

[0101] In summary, the bio-carbon source of the present invention shows better denitrification performance than the glucose carbon source: higher denitrification rate, lower denitrification carbon source unit consumption and higher TN removal rate.

[0102] 3.3 Conclusion

[0103] (1) The bio-composite carbon source of the present invention has a high denitrification rate and denitrification effect. Under the same carbon source COD dosing concentration, the denitrification rate, total nitrogen removal rate and nitrate nitrogen of the three carbon sources of the present invention are higher than those of the glucose carbon source currently used in the plant. Among them, Bio-carbon source No. 5 performs the best, with the denitrification rate relatively increased by about 125%, the total nitrogen removal rate relatively increased by 56.12%, and the nitrate nitrogen removal rate relatively increased by 71.20%.

[0104] (2) The biological carbon source of the present invention can reduce the operation cost under the same conditions. Under the conditions of this bench-scale test, the ΔCOD / ΔTN of denitrification for the three biological carbon sources of the present invention is lower than that of the currently used glucose carbon source. Among them, the 5# biological carbon source has the lowest denitrification unit consumption, which is 43.5% lower than that of glucose.

[0105] The above-described embodiments only represent the specific implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all belong to the protection scope of the present invention.

Claims

1. A composite biological carbon source for sewage treatment, characterized in that, It uses the waste by-products in the fermentation process as the basic raw material. Through hydrolase, the high-molecular organic matter in the waste by-products is decomposed into small-molecular organic matter that is easily absorbed and utilized by organisms. After solid-liquid separation, a carbon source mother liquor is obtained, and then an appropriate proportion of sodium acetate and easily degradable organic matter are added to obtain the composite biological carbon source.

2. The preparation method of the composite biological carbon source for sewage treatment according to claim 1, characterized in that, Specifically, it includes the following steps: S1. Centrifugally separate the solid and liquid of the waste by-products in the fermentation process to obtain a supernatant and solid substances; S2. Add water to the above solid substances to form a slurry-like mixture, add a composite biological enzyme to the mixture, mix evenly, carry out aerobic fermentation, and after the fermentation is completed, carry out centrifugal solid-liquid separation to obtain a separation liquid; S3. Mix the above supernatant and separation liquid to obtain a carbon source mother liquor, and then add sodium acetate and easily degradable organic matter to the carbon source mother liquor, and stir well to obtain the composite biological carbon source.

3. According to the preparation method of the composite biological carbon source for sewage treatment described in claim 2, characterized in that, In the step S1, the rotation speed of the centrifugal separation is 5000 r / min, the temperature is 4 °C, and the time is 5 min.

4. According to the preparation method of the composite biological carbon source for sewage treatment described in claim 2, characterized in that, In the step S2, the total mass of the solid substances and water is 1.5 to 3 times the mass of the supernatant.

5. According to the preparation method of the composite biological carbon source for sewage treatment described in claim 2, characterized in that, In the step S2, the addition amount of the composite biological enzyme in the mixture is 1 to 15 g / L.

6. According to the preparation method of the composite biological carbon source for sewage treatment described in claim 5, characterized in that, The composite biological enzyme is a combination of any two or more of dextranase, neutral protease, β-glycanase or papain.

7. According to the preparation method of the composite biological carbon source for sewage treatment described in claim 2, characterized in that, In the step S2, the temperature of the aerobic fermentation is 30 to 50 °C, the stirring rate is 60 to 120 r / min, and the fermentation time is 6 to 48 h.

8. According to the preparation method of the composite biological carbon source for sewage treatment described in claim 2, characterized in that, In the step S3, the masses of the carbon source mother liquor, sodium acetate and easily degradable organic matter are (70 to 100):(0 to 10):(0 to 20).

9. According to the preparation method of the composite biological carbon source for sewage treatment described in claim 7, characterized in that, The easily degradable organic matter is any one or several of ethylene glycol, methanol, ethanol, propanol, propylene glycol, glycerol, formic acid, propionic acid, butyric acid, valeric acid, citric acid, glucose or starch.

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