Additional carbon source material for sewage denitrification as well as preparation method and application thereof
By mixing Bacillus subtilis bacterial fluid and Candida prion bacterial fluid with the pretreated liquor lees and fermenting them on standby, obtaining liquid added carbon source materials, which solves the problems of high energy consumption, low treatment efficiency and high cost when the liquor lees are used as carbon sources in sewage treatment, and achieves efficient sewage denitrification and carbon source utilization.
Patent Information
- Application Number
- CN202510090514.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-21
- Publication Date
- 2025-05-02
AI Technical Summary
In sewage treatment, when using wine lees as a carbon source, there are problems such as high energy consumption, low treatment efficiency and high cost.
By mixing Bacillus subtilis and Candida bacterial solution with pretreated liquor lees, it is allowed to stand and fermented to obtain a liquid added carbon source material. This method is relatively simple, easy to operate and control, and improves the bioavailability of the carbon source.
This method improves the efficiency of sewage denitrification, the carbon source utilization efficiency reaches 83.25%, and the nitr nitrogen removal rate is 54.6%, while reducing technical difficulty and operating costs.
Smart Images
Figure CN119913210A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to an external carbon source material for sewage denitrification and a preparation method and application thereof. Background Art
[0002] With the improvement of urban sewage treatment plant discharge standards and stricter tailwater total nitrogen limits, biological denitrification in sewage treatment plants generally faces the problem of insufficient carbon sources, and external carbon sources need to be supplemented as electron donors. Traditional external carbon sources usually use acetic acid, sodium acetate, methanol, glucose, etc., but these small molecular organic substances that can be quickly utilized by organisms increase the energy consumption of sewage treatment plants. With the development of concepts and the advancement of waste resource utilization technology, more and more natural organic wastes and artificially synthesized organic macromolecular polymers are being developed and used as external carbon sources.
[0003] At present, the technology of adding carbon source mainly includes traditional carbon source, industrial wastewater, hydrolyzed liquid of kitchen waste, sludge digestion liquid, agricultural waste, etc. Among them, agricultural waste has low cost and can be used sustainably. After pretreatment, the carbon source substances can be effectively released. The chemical composition and physical properties of different types of agricultural waste (such as corn stalks, rice husks, peanut shells, livestock and poultry manure, etc.) vary greatly, and their carbon-nitrogen ratio, cellulose, hemicellulose, lignin and other proportions are unstable, which makes it difficult to predict and control their utilization efficiency as carbon sources.
[0004] Liquor lees are the main by-product of the liquor brewing industry. They inherit the organic components such as protein, starch, cellulose, and fat in the brewing raw materials, and have the value of resource utilization. On the other hand, wine lees have high moisture and microbial content, are easy to corrupt during storage, and produce harmful gases and high-concentration organic leachate during stacking. If not properly handled and disposed of in time, there will be environmental pollution risks. Although wine lees are regarded as waste, their cost as raw materials is relatively low, and they are rich in residual nutrients, including crude fiber, crude protein, fat, starch and other components. Converting them into carbon sources for sewage treatment can not only solve the pollution problem of wine lees, but also provide a cheap and efficient carbon source for sewage treatment, reduce sewage treatment costs, and improve treatment efficiency.
[0005] However, distiller's grains often contain a large amount of difficult-to-degrade substances such as cellulose, hemicellulose and lignin, which require pretreatment (such as crushing, hydrolysis, enzymatic hydrolysis, etc.) to release usable sugars and organic matter. Even after pretreatment, some complex organic matter in the distiller's grains, such as lignin, is still difficult to completely convert into usable small-molecule organic matter, resulting in low carbon source utilization efficiency and affecting the sewage treatment effect. For some pretreatment methods, such as high-temperature and high-pressure hydrolysis, a large amount of energy consumption is required, which increases operating costs and may produce greenhouse gases, which is not conducive to environmental protection; chemical hydrolysis may produce some harmful by-products or intermediates, causing secondary pollution, which requires further treatment, increasing treatment costs and complexity. For example, acid hydrolysis may produce toxic aldehydes. Summary of the invention
[0006] The technical problem to be solved by the present invention is that when distiller's grains are used as a carbon source for sewage treatment, there are problems of high energy consumption, low treatment efficiency and high cost.
[0007] The technical solution adopted by the present invention to solve its technical problem is:
[0008] In a first aspect, the present invention provides a method for preparing an external carbon source material for wastewater denitrification, comprising the following steps:
[0009] S1: mixing equal volumes of Bacillus subtilis bacterial solution and Candida utilis bacterial solution to obtain a mixed bacterial solution;
[0010] S2: washing the liquor lees with water and drying them, then adding NaOH solution to carry out water bath reaction, and after the reaction is completed, filtering, washing, drying, sterilizing, and naturally cooling to obtain pretreated lees;
[0011] S3 inoculates the mixed bacterial liquid into the pretreated wine lees, mixes well and seals, allows static fermentation, and centrifuges to obtain the supernatant to obtain a liquid added carbon source material.
[0012] In the above step S1, the bacterial density of the Bacillus subtilis liquid is 10 7 ~10 8 CFU / ml.
[0013] In the above step S1, the bacterial density of the Candida utilis bacterial solution is 10 7 ~10 8 CFU / ml.
[0014] Furthermore, the preparation method of the above-mentioned Bacillus subtilis bacterial liquid is: inoculate the Bacillus subtilis strain into LB liquid culture medium, place it in a shaking incubator at 35-38° C., and activate and culture it at 145-155 r / min for 23-25 hours.
[0015] Furthermore, the preparation method of the above-mentioned Candida utilis bacterial liquid is: inoculate the Candida utilis strain into YPD liquid culture medium, place it in a shaking incubator at 29-31° C., and activate and culture it at 145-155 r / min for 23-25 hours.
[0016] In the above step S2, the mass ratio of the dried liquor lees to the NaOH solution is (0.9-1.1):(9-11).
[0017] Furthermore, the main components of the above-mentioned liquor lees are crude protein 5-8%, crude fiber 4-6%, starch 10-12%, crude fat 0.5-0.6%, and crude ash 1.5-2%.
[0018] Furthermore, the mass concentration of the above-mentioned NaOH solution is 2%.
[0019] In the above step S2, the washing is performed by washing with ultrapure water.
[0020] In the above step S2, the drying is drying to constant weight.
[0021] In the above step S2, the water bath reaction is carried out at 80-90° C. for 55-65 min.
[0022] In the above step S2, the sterilization is performed by high pressure sterilization at 119-121° C. for 19-21 min.
[0023] In the above step S3, the mixed bacterial solution is inoculated into the pretreated wine lees at a ratio of 10 ml:100 g.
[0024] In the above step S3, the static fermentation is performed at 26-34° C. for 4-6 days.
[0025] In the above step S3, the centrifugation is performed at 9900-11000 r / min for 9-11 min.
[0026] In a second aspect, the present invention provides an external carbon source material for wastewater denitrification prepared by the above preparation method.
[0027] In a third aspect, the present invention provides an application of the above-mentioned additional carbon source material for sewage denitrification in a sewage treatment denitrification denitrification process: adding the additional carbon source material for sewage denitrification to the denitrified sewage and / or sludge at a carbon-nitrogen ratio of 2.5 to 3.
[0028] The beneficial effects of the present invention are as follows: compared with some complex pretreatment technologies, the process of mixed bacteria fermentation of the present invention is relatively simple, easy to operate and control, and reduces the technical difficulty and the requirements for equipment; and compared with some complex carbon sources, VFAs have higher bioavailability and are easier to be absorbed and utilized by denitrifying bacteria, thereby promoting the denitrification reaction, improving the stability of the sewage treatment system, and reducing the reduction in denitrification efficiency due to insufficient or fluctuating carbon source supply.
[0029] The present invention mainly uses liquor lees as raw materials to produce a new type of carbon source. Not only is the preparation process simple, the operation is convenient, and the production cycle is short, but it can also expand the comprehensive utilization of lees and reduce its pollution to the environment. The external carbon source material prepared by the method of the present invention is used as an additional carbon source for the denitrification process. The carbon source utilization efficiency is as high as 83.25% during the denitrification process, and the nitric nitrogen removal rate is 54.6%. The external carbon source material of the present invention is safe and non-toxic. Its promotion and application not only solves the disposal problem of lees, the waste of liquor brewing, of many liquor manufacturers, but also has great significance for opening up new carbon source substitutes for sewage treatment to promote the reuse of lees resources and the sustainable development of sewage treatment. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 is a flow chart of the preparation method of the external carbon source material;
[0031] Figure 2 is the acid production of the original liquor lees and the added carbon source materials 1 to 3;
[0032] Figure 3 are the components of the added carbon source materials 1 to 3; in the figure, (a) is the COD content, (b) is the total nitrogen content, (c) is the nitrate content, and (d) is the nitrite content;
[0033] Figure 4 It is the denitrification effect of the added carbon source materials 1 to 3; in the figure, (a) is the nitrate nitrogen degradation law, (b) is the COD degradation law, and (c) is the nitrite degradation law. DETAILED DESCRIPTION
[0034] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clear, the present application is further described in detail below in combination with the implementation methods. Unless otherwise defined, all scientific and technological terms used herein have the same meanings as understood by ordinary technicians in the field.
[0035] Preparation of external carbon source materials for wastewater denitrification, process flow Figure 1 As shown, the specific steps include:
[0036] 1. Preparation of mixed bacterial solution:
[0037] (1) Inoculate Bacillus subtilis into LB liquid culture medium, place in a shaker at 35-38°C, and activate and culture at 145-155 r / min for 23-25 h to obtain a Bacillus subtilis bacterial solution with a bacterial solution concentration of 10 7 ~10 8 CFU / ml;
[0038] (2) The utilis strain was inoculated into a YPD liquid culture medium, placed in a shaking incubator at 29-31°C, and activated and cultured at 145-155 r / min for 23-25 h to obtain a utilis bacterial solution having a bacterial solution concentration of 10 7 ~10 8 CFU / ml;
[0039] (3) Mix equal volumes of the Bacillus subtilis culture solution and the Candida utilis culture solution to obtain a mixed culture solution.
[0040] 2. Pretreatment of liquor lees:
[0041] (1) The liquor lees are washed with water and then dried to a constant weight, and then a 2% (w / v) NaOH solution is added to the dried liquor lees at a mass ratio of (0.9-1.1):(9-11), and the mixture is in a water bath at 80-90° C. for 55-65 min;
[0042] (2) After the water bath reaction is completed, the liquor lees are filtered and washed with ultrapure water, and then dried to constant weight. After drying, the liquor lees are placed in a conical flask, which is sealed with a sealing film and covered with aluminum foil, and then sterilized by high pressure at 119-121°C for 19-21 minutes. After sterilization, the aluminum foil and sealing film are removed, and the pretreated lees are obtained after natural cooling.
[0043] 3. Inoculate the mixed bacterial liquid into the pretreated wine lees at a ratio of 10 ml: 100 g, stir evenly at natural pH, seal with sealing film, and ferment at 26-34 ° C for 4-6 days. Centrifuge the fermented mixture at 10000 r / min for 10 min, take the supernatant, and obtain the added carbon source material.
[0044] Specific examples will be listed below to explain the scheme of the present invention. It will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be considered as limiting the scope of the present invention. Where specific techniques or conditions are not indicated in the examples, the techniques or conditions described in the literature in this area or the product instructions are used. Reagents or instruments used that do not indicate manufacturers are all conventional products that can be obtained commercially.
[0045] Example 1 Preparation of an external carbon source material for wastewater denitrification
[0046] 0.1 g of Bacillus subtilis was inoculated into LB liquid medium, placed in a 37°C shaker, and activated and cultured at 150 r / min for 24 h to obtain a Bacillus subtilis bacterial solution with a bacterial solution concentration of 10 7 ~10 8 CFU / ml. 0.1 g of Candida utilis strain was inoculated into YPD liquid culture medium, placed in a 30°C shaker, and activated and cultured at 150 r / min for 24 h to obtain a Candida utilis bacterial solution with a bacterial solution concentration of 10 7 ~10 8 The Bacillus subtilis bacterial solution and the Candida utilis bacterial solution were mixed at a volume ratio of 1:1 to obtain a mixed bacterial solution.
[0047] Prepare liquor lees, the main components of which are 5-8% crude protein, 4-6% crude fiber, 10-12% starch, 0.5-0.6 crude fat, and 1.5-2% crude ash. Wash the liquor lees with water and then dry them to constant weight. Add 2% (w / v) NaOH solution to the dried liquor lees at a mass ratio of 1:10, and water bath them at 85°C for 60 minutes. After the water bath reaction is completed, filter and wash with ultrapure water, then dry the liquor lees to constant weight, put 80g of the dried lees into a 250mL conical flask, seal the conical flask with a sealing film and cover it with aluminum foil, and then sterilize it at 120°C for 20 minutes. After the sterilization is completed, remove the aluminum foil and sealing film, and cool it naturally to obtain the pretreated lees.
[0048] Take 10% (10ml:100g) of the mixed bacterial liquid and inoculate it into the pretreated wine lees, stir it evenly under natural pH, seal it with a sealing film, and place the sealed conical flask in a constant temperature incubator at 26°C, 30°C, and 34°C for static fermentation for 5 days. Centrifuge the fermented mixture at 10000r / min for 10min, take the supernatant, and obtain external carbon source material 1 (26°C), external carbon source material 2 (30°C), and external carbon source material 3 (34°C).
[0049] Example 2 Acid production test of added carbon source material
[0050] Test method: add phosphoric acid to the original liquor lees and the external carbon source materials 1 to 3, adjust the pH value of the sample to 2 to 3, and use gas chromatography to measure and detect the acid production. The results are as follows: Figure 2 shown.
[0051] Volatile fatty acids (VFAs) are a class of carboxylic acids with one or more carbon chains that can volatilize in aqueous solution and are easily volatilized at room temperature and pressure. Common VFAs include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, etc. The carbon chain length of these acids is usually between 2 and 6 carbon atoms. Denitrifying bacteria absorb VFAs through specific transport proteins on their cell membranes and use VFAs as electron donors to convert nitrate ions (NO3 - ) is reduced to nitrogen (N2). During the oxidation process of VFAs, denitrifying bacteria will produce ATP (adenosine triphosphate) to provide energy for cell growth and metabolism, and finally completely oxidize VFAs to carbon dioxide (CO2).
[0052] Depend on Figure 2 It can be seen that in the fermentation system, the content of acetic acid, ethanol and n-butyric acid produced by the added carbon source material 2 is the highest, which are 1921.05 mg / L, 820.35 mg / L and 50.62 mg / L respectively; the content of ethanol and acetic acid is increased by 825.99 mg / L and 500.13 mg / L respectively compared with the original liquor lees. Compared with the original liquor lees, the acid production of the added carbon source material prepared by the present invention is significantly improved, which proves that the added carbon source material prepared by the present invention can effectively improve the denitrification efficiency.
[0053] Example 3 Component Detection of Added Carbon Source Material
[0054] The components of the liquid added carbon source materials 1 to 3 were tested respectively, and the results were as follows: Figure 3 shown.
[0055] Depend on Figure 3 It can be seen that the COD concentration of the liquid added carbon source material is 78-87 g / L, the total nitrogen concentration is about 1.2 g / L, and the nitrate nitrogen concentration is 0.02-0.6 g / L. After dilution, the nitrate nitrogen concentration as a carbon source is negligible.
[0056] Example 4 Application and Effect of Added Carbon Source Material
[0057] Application method: Wash the laboratory cultured sludge with deionized water, add deionized water and then centrifuge, skim off the supernatant, add deionized water and stir evenly, then centrifuge to remove the supernatant, wash three times, and the washed sludge is used as the sludge for denitrification experiment. Add the denitrified sludge to the conical flask and control the sludge concentration MLSS at about 3000. According to the carbon-nitrogen ratio of 2.86, add 1 to 3 liquid additional carbon source materials to the conical flask respectively, and distilled water to 250mL. Perform a shaking experiment to detect the denitrification effect. The results are as follows: Figure 4 shown.
[0058] Depend on Figure 4It can be seen that nitrate nitrogen rapidly decreased within 0-60 minutes, among which liquid external carbon source material 3 had the best effect in removing nitrate nitrogen, with a removal rate of 54.6% and a carbon source utilization efficiency (calculated according to the growth before and after sludge reaction) of 83.25%. The nitrate nitrogen removal rates of the blank group, liquid external carbon source materials 1 and 2 were 25.79%, 52.01% and 53.6%, respectively, and the carbon source utilization rates were 73.81%, 74.47% and 73.45%.
Claims
1. A method for preparing an external carbon source material for wastewater denitrification, characterized in that: The steps include: S1: mixing equal volumes of Bacillus subtilis bacterial solution and Candida utilis bacterial solution to obtain a mixed bacterial solution; S2: washing the liquor lees with water and drying them, then adding NaOH solution to carry out water bath reaction, and after the reaction is completed, filtering, washing, drying, sterilizing, and naturally cooling to obtain pretreated lees; S3 inoculates the mixed bacterial liquid into the pretreated wine lees, mixes well and seals, allows static fermentation, and centrifuges to obtain the supernatant to obtain a liquid added carbon source material.
2. The method for preparing an external carbon source material for wastewater denitrification according to claim 1, characterized in that: In step S1, the bacterial density of the Bacillus subtilis liquid is 10 7 ~10 8 CFU / ml, the bacterial density of the Candida utilis bacterial solution is 10 7 ~10 8 CFU / ml.
3. The method for preparing an external carbon source material for wastewater denitrification according to claim 2, characterized in that: The preparation method of Bacillus subtilis liquid is as follows: inoculate the Bacillus subtilis strain into LB liquid culture medium, place it in a shaking incubator at 35-38° C., and activate and culture it at 145-155 r / min for 23-25 hours; The preparation method of the Candida utilis bacterial liquid is as follows: the Candida utilis strain is inoculated into a YPD liquid culture medium, placed in a shaking incubator at 29-31° C., and activated and cultured at 145-155 r / min for 23-25 hours.
4. The method for preparing an external carbon source material for wastewater denitrification according to claim 1, characterized in that: In step S2, the mass ratio of the dried liquor lees to the NaOH solution is (0.9-1.1):(9-11).
5. The method for preparing an external carbon source material for wastewater denitrification according to claim 4, characterized in that: The main components of liquor lees are crude protein 5-8%, crude fiber 4-6%, starch 10-12%, crude fat 0.5-0.6%, and crude ash 1.5-2%; the mass concentration of the NaOH solution is 2%.
6. The method for preparing an external carbon source material for wastewater denitrification according to claim 1, characterized in that: In step S2, at least one of the following conditions is satisfied: The washing comprises: washing with ultrapure water; The drying comprises: drying to constant weight; The water bath reaction is: water bathing at 80-90°C for 55-65 minutes; The sterilization is as follows: high pressure sterilization at 119-121° C. for 19-21 min.
7. The method for preparing an external carbon source material for wastewater denitrification according to claim 1, characterized in that: In step S3, the mixed bacterial solution is inoculated into the pretreated wine lees at a ratio of 10 ml:100 g.
8. The method for preparing an external carbon source material for wastewater denitrification according to claim 1, characterized in that: In step S3, at least one of the following conditions is satisfied: The static fermentation comprises: static fermentation at 26-34° C. for 4-6 days; The centrifugation is as follows: centrifugation at 9900-11000 r / min for 9-11 min.
9. An external carbon source material for wastewater denitrification prepared by the preparation method according to any one of claims 1 to 8.
10. Use of the external carbon source material for sewage denitrification prepared by the preparation method according to any one of claims 1 to 8, or the external carbon source material for sewage denitrification according to claim 9 in a sewage treatment denitrification and denitrification process, characterized in that: According to the carbon-nitrogen ratio of 2.5 to 3, an additional carbon source material for sewage denitrification is added to the denitrified sewage and / or sludge.