A composite carbon source additive and a preparation method thereof

Abstract

The present application belongs to the technical field of sewage treatment, and particularly relates to a composite carbon source additive and a preparation method thereof. The composite carbon source additive comprises the following components in parts by weight: 30-40 parts of sugarcane residue, 8-12 parts of polyvinyl alcohol derivative, 2-4 parts of functional filler, 5-8 parts of potassium citrate and 5-8 parts of sodium pyruvate. The preparation process of the polyvinyl alcohol derivative is as follows: polyvinyl alcohol, 1,3,5-benzene trisulfonic acid, triethylamine and 4-dimethylaminopyridine are added into dichloromethane for reaction, and then filtration, washing and drying are performed to obtain the polyvinyl alcohol derivative. The composite carbon source additive can slowly release and continuously and stably provide carbon source in the denitrification process, promote the denitrification process and improve the denitrification efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of sewage treatment, and particularly relates to a composite carbon source additive and a preparation method thereof. BACKGROUND

[0002] The significant increase of nitrogen content in water sources will promote the large-scale breeding of algae such as blue-green algae and green algae. The overgrowth of algae will reduce the dissolved oxygen in the water body and produce toxins, ultimately leading to water quality deterioration, causing serious harm to aquatic organisms and human health. The nitrogen in sewage mainly exists in the forms of ammonia nitrogen, organic nitrogen, nitrite and nitrate, and biological denitrification is the process of converting nitrogen-containing pollutants into nitrogen gas and releasing it into the air; its basic principle includes three steps: ammonification is to convert organic nitrogen into ammonia nitrogen; nitrification is to convert ammonia nitrogen into nitrate; denitrification is to reduce nitrate into nitrogen gas and release it. In the process of denitrification, sufficient carbon source is needed to provide nutrition and energy for heterotrophic microorganisms to efficiently complete assimilation and dissimilation, so as to achieve the purpose of removing nitrogen-containing pollutants in sewage.

[0003] In the biochemical treatment process of sewage, the carbon source available for denitrifying bacteria mainly includes the original carbon source in the sewage and the additional carbon source. Among them, the use of additional carbon source is of great significance to improve the denitrification efficiency. At present, common additional carbon sources include methanol, acetic acid and the like. However, these traditional carbon sources have certain limitations in practical application. On the one hand, they may not achieve good denitrification effect under the premise of being non-toxic, harmless and environmentally friendly; on the other hand, their cost performance needs to be improved.

[0004] Therefore, there is an urgent need for a composite carbon source additive that can meet the green environmental protection requirements, promote the rapid progress of denitrification and denitrification reaction, improve the denitrification efficiency and reduce the treatment cost. SUMMARY

[0005] In order to overcome the deficiencies of the prior art, one of the purposes of the present application is to provide a composite carbon source additive, which can quickly start and continuously and stably provide carbon source in the denitrification process, strengthen the denitrification effect and improve the denitrification efficiency.

[0006] One of the purposes of the present application is achieved by adopting the following technical scheme:

[0007] A composite carbon source additive, by weight, comprises the following components: 30-40 parts of sugarcane residue, 8-12 parts of polyvinyl alcohol derivative, 2-4 parts of functional filler, 5-8 parts of potassium citrate and 5-8 parts of sodium pyruvate.

[0008] The preparation process of the polyvinyl alcohol derivative is: polyvinyl alcohol, 1, 3, 5-benzene trisulfonic acid, triethylamine, 4-dimethylaminopyridine are added to dichloromethane for reaction, and then filtered, washed and dried to obtain the polyvinyl alcohol derivative.

[0009] Further, the mass ratio of the polyvinyl alcohol, 1, 3, 5-benzene trisulfonic acid, triethylamine, 4-dimethylaminopyridine and dichloromethane is 1: (3-4): (3-3.5): (0.2-0.3): 50.

[0010] Further, the reaction time is 8-12h.

[0011] Further, the preparation process of the functional filler is: adding sepiolite, 1-bromoheptane, sodium carbonate and potassium iodide into dioxane, heating and reacting, and then filtering, washing and drying to obtain the functional filler.

[0012] Further, the mass ratio of the sepiolite, 1-bromoheptane, sodium carbonate, potassium iodide and dioxane is 3: (1-2): (2-4): (0.1-0.2): 80.

[0013] Further, the heating reaction temperature is 90-100°C, and the time is 3-5h.

[0014] Further, the preparation process of the sugarcane residue is: drying the waste sugarcane residue at 50°C to a constant weight, adding to 2wt% sodium hydroxide aqueous solution for 10-12h, washing with water to neutral, and drying at 50°C to a constant weight to obtain the sugarcane residue.

[0015] Further, the dosage ratio of the waste sugarcane residue and the sodium hydroxide aqueous solution is 0.05-0.10g: 1mL.

[0016] The second object of the present application is to provide a preparation method of the composite carbon source additive.

[0017] The second object of the present application is achieved by the following technical scheme:

[0018] The preparation method of the composite carbon source additive comprises the following steps: dispersing the sugarcane residue, the functional filler, the potassium citrate and the sodium pyruvate in water, adding the polyvinyl alcohol derivative into the water, mixing uniformly to obtain a mixture, and then performing 3 freeze-thaw cycles, drying after the last thawing to obtain the composite carbon source additive.

[0019] Further, the freeze-thaw cycle is: freezing the mixture at-20°C to-15°C for 18-24h, and then thawing at room temperature, which is recorded as 1 freeze-thaw cycle; the mass ratio of the sugarcane residue and water is (3-4): 10.

[0020] Compared with the prior art, the application has the beneficial effects that:

[0021] 1. The application provides a composite carbon source additive, which is prepared by scientifically proportioning pretreated bagasse, a polyvinyl alcohol derivative, a functional filler, potassium citrate and sodium pyruvate, can slowly release and continuously and stably provide carbon sources in the denitrification process, and improves the denitrification efficiency.

[0022] (1) The polyvinyl alcohol derivative is introduced in the application, which introduces sulfonic acid groups on the polyvinyl alcohol, can provide more active sites for the carbon source, promote the utilization of the carbon source by microorganisms, and thus improve the efficiency of the denitrification process; and can also avoid the rapid decomposition of the carbon source in water, so that the composite carbon source additive can be slowly and stably released in water. (2) The functional filler is prepared by introducing a hydrophobic fatty chain on the surface of sepiolite, the surface hydrophobicity of the functional filler is enhanced, the functional filler can better adsorb hydrophobic organic matter such as organic matter (such as lignin and fatty acids) in the bagasse, the carbon source can be prevented from being rapidly released at the initial stage of being put into water, and the release stability and biological availability of the carbon source are improved. Meanwhile, the modified sepiolite has a larger specific surface area and a more abundant pore structure, can improve the adsorption capacity and the adhesion capacity to microorganisms, and thus promotes the denitrification process.

[0023] 2. The application provides a preparation method of the composite carbon source additive. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The infrared spectrum of the polyvinyl alcohol derivative obtained in Example 1 of the application is shown in the figure.

[0025] Figure 2 The infrared spectrum of the functional filler obtained in Example 1 of the application is shown in the figure. DETAILED DESCRIPTION

[0026] In the following, the application is further described in combination with the drawings and the specific embodiments, and it should be noted that, under the premise of no conflict, the embodiments described below or the technical features between the embodiments can be combined in any manner to form new embodiments. The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, such as the conventional products obtained through the market channels, are not specifically mentioned.

[0027] Example 1

[0028] A composite carbon source additive, by weight, comprises the following components: 35 parts of bagasse, 10 parts of a polyvinyl alcohol derivative, 3 parts of a functional filler, 7 parts of potassium citrate and 7 parts of sodium pyruvate.

[0029] The preparation process of the bagasse is as follows: the waste bagasse is dried at 50°C to constant weight, soaked in 2wt% sodium hydroxide solution for 11h, and the solid-liquid ratio is 0.06g / mL; after washing to neutral, it is dried at 50°C to constant weight to obtain the bagasse.

[0030] The preparation process of the polyvinyl alcohol derivative is as follows: polyvinyl alcohol 1 part, 1,3,5-benzene trisulfonic acid 3.5 parts, triethylamine 3.2 parts, 4-dimethylamino pyridine 0.25 parts are added to 50 parts of dichloromethane, reacted at room temperature for 10h, filtered, washed with deionized water, and dried in an oven at 100°C to obtain the polyvinyl alcohol derivative.

[0031] The preparation process of the functional filler is as follows: sepiolite 3 parts, 1-bromoheptane 1.5 parts, sodium carbonate 3 parts, potassium iodide 0.15 parts are added to 80 parts of dioxane, reacted at 100°C for 4h, filtered, washed with deionized water, and dried in an oven at 100°C to obtain the functional filler.

[0032] The preparation method of the above-mentioned composite carbon source additive comprises the following steps: the bagasse, the functional filler, the potassium citrate, and the sodium pyruvate are dispersed in water, wherein the mass ratio of the bagasse and the water is 3.5:10; then the polyvinyl alcohol derivative is added and uniformly mixed, and the mixture is frozen at-18°C for 20h; then it is thawed at room temperature, which is recorded as the first freeze-thaw cycle; the cycle is repeated for 3 times, and after the last thawing, it is dried to obtain the composite carbon source additive.

[0033] Example 2

[0034] A composite carbon source additive, by weight fraction, comprises the following components: bagasse 30 parts, polyvinyl alcohol derivative 8 parts, functional filler 2 parts, potassium citrate 5 parts, and sodium pyruvate 5 parts.

[0035] The preparation process of the bagasse is as follows: the waste bagasse is dried at 50°C to constant weight, soaked in 2wt% sodium hydroxide solution for 10h, and the solid-liquid ratio is 0.05g / mL; after washing to neutral, it is dried at 50°C to constant weight to obtain the bagasse.

[0036] The preparation process of the polyvinyl alcohol derivative is as follows: polyvinyl alcohol 1 part, 1,3,5-benzene trisulfonic acid 3 parts, triethylamine 3 parts, and 4-dimethylamino pyridine 0.2 parts are added to 50 parts of dichloromethane, reacted at room temperature for 8h, filtered, washed with deionized water, and dried in an oven at 100°C to obtain the polyvinyl alcohol derivative.

[0037] The preparation process of the functional filler is as follows: sepiolite 3 parts, 1-bromoheptane 1 part, sodium carbonate 2 parts, and potassium iodide 0.1 parts are added to 80 parts of dioxane, reacted at 100°C for 3h, filtered, washed with deionized water, and dried in an oven at 100°C to obtain the functional filler.

[0038] The preparation method of the composite carbon source additive comprises the following steps: dispersing bagasse, functional filler, potassium citrate and sodium pyruvate in water, wherein the mass ratio of the bagasse and water is 3:10; then adding polyvinyl alcohol derivative into the mixture and uniformly mixing; freezing the mixture at-20°C for 18h; then thawing at room temperature, which is recorded as one freeze-thaw cycle; repeating the cycle for three times; and finally drying after the last thawing to obtain the composite carbon source additive.

[0039] Example 3

[0040] The composite carbon source additive comprises the following components in parts by weight: bagasse 40 parts, polyvinyl alcohol derivative 12 parts, functional filler 4 parts, potassium citrate 8 parts, and sodium pyruvate 8 parts.

[0041] The preparation process of the bagasse is as follows: drying the waste bagasse at 50°C to a constant weight, soaking in 2wt% sodium hydroxide aqueous solution for 12h, and the solid-liquid ratio is 0.10g / mL; washing with water to neutral, and drying at 50°C to a constant weight to obtain the bagasse.

[0042] The preparation process of the polyvinyl alcohol derivative is as follows: adding polyvinyl alcohol 1 part, 1,3,5-benzene trisulfonic acid 4 parts, triethylamine 3.5 parts, and 4-dimethylamino pyridine 0.3 parts into 50 parts of dichloromethane, reacting at room temperature for 12h, filtering, washing with deionized water, and drying in an oven at 100°C to obtain the polyvinyl alcohol derivative.

[0043] The preparation process of the functional filler is as follows: adding sepiolite 3 parts, 1-bromoheptane 2 parts, sodium carbonate 4 parts, and potassium iodide 0.2 parts into 80 parts of dioxane, filtering after reacting at 100°C for 5h, washing with deionized water, and drying in an oven at 100°C to obtain the functional filler.

[0044] The preparation method of the composite carbon source additive comprises the following steps: dispersing bagasse, functional filler, potassium citrate and sodium pyruvate in water, wherein the mass ratio of the bagasse and water is 4:10; then adding polyvinyl alcohol derivative into the mixture and uniformly mixing; freezing the mixture at-15°C for 24h; then thawing at room temperature, which is recorded as one freeze-thaw cycle; repeating the cycle for three times; and finally drying after the last thawing to obtain the composite carbon source additive.

[0045] Comparative Example 1

[0046] The comparative example is basically the same as Example 1, except that the polyvinyl alcohol derivative is replaced by polyvinyl alcohol.

[0047] Comparative Example 2

[0048] The comparative example is basically the same as Example 1, except that the functional filler is replaced by sepiolite.

[0049] Test Example 1

[0050] Figure 1 and Figure 2 They are the infrared spectra of the polyvinyl alcohol derivative and the functional filler obtained in Example 1 respectively.

[0051] Depend on Figure 1 It can be seen that 3600cm -1 The peak shape changed slightly, proving that some of the hydroxyl groups of polypropylene glycol were replaced by sulfonate groups; 1170 cm -1 The absorption peak at 750-860 cm -1 The characteristic peaks of substitution of benzene ring were displayed, indicating that the polyvinyl alcohol derivative had been successfully prepared.

[0052] Figure 2 It can be seen that at 2915-2845cm -1 The characteristic peak of methylene appeared at , indicating the successful recombination of 1-bromoheptane and sepiolite.

[0053] Test Example 2

[0054] In order to explore the carbon release ability of the composite carbon source additives obtained in Examples 1-3 and Comparative Examples 1-2, the following test was conducted: the composite carbon source additives obtained in Examples 1-3 and Comparative Examples 1-2 were placed in 350 mL of deionized water, 9 g per group, sealed and shaken at 120 rpm at room temperature, and samples were taken at 12 h, 48 h, and 120 h, respectively, and the COD of each group of samples was measured. cr The concentrations are shown in Table 1.

[0055] Table 1

[0056]

[0057] The test results in Table 1 show that Examples 1-3 of the present invention were able to slowly and steadily release the carbon source over a 120-hour period. Compared to Example 1, Comparative Example 1 (in which the polyvinyl alcohol derivative was replaced with polyvinyl alcohol) exhibited a higher CODcr content during the initial release period. This is likely due to the combined effect of the introduced polyvinyl alcohol derivative and the filler, which prevented the carbon source from being rapidly decomposed during the initial release period, leading to excessive consumption.

[0058] In addition, compared with Example 1, the composite carbon source of Comparative Example 2 (replacing the functional filler with sepiolite) has a higher carbon release rate in the initial stage and a lower carbon release rate in the later stage, indicating that the functional filler in the composite carbon source additive of the present invention, the hydrophobic fatty chain introduced on the surface of sepiolite can better adsorb the carbon source in sugarcane bagasse and also provide more carbon source.

[0059] Test Example 3

[0060] In order to explore the denitrification ability of the composite carbon source additives obtained in Examples 1-3 and Comparative Examples 1-2, the following test was performed.

[0061] 200 mL of deionized water was taken, and potassium nitrate and potassium dihydrogen phosphate (N:P = 5:1) was added to prepare a nitrate solution with a concentration of 30 mg / L, simulating wastewater. The solution was divided into the groups of Examples 1-3 and Comparative Examples 1-2, and 0.3 g of denitrifying bacteria and 10 g of the composite carbon source additives were added to each group. After sealing, the solution was oscillated at 120 rpm, and continuously cultured for 15 days. The removal rates of NO3 - -N and NO2 - -N were calculated. The results are shown in Table 2.

[0062] Table 2

[0063]

[0064] As can be seen from the test results in Table 2, the removal rates of NO3 - -N and NO2 - -N in Examples 1-3 of the present application were all higher than 90%. This shows that the composite carbon source additives obtained in the present application have good denitrification effect. This is because the denitrifying bacteria use the carbon source as an electron donor to reduce nitrate (NO3 - ) and nitrite (NO2 - ) to nitrogen (N2) under anoxic conditions, thereby achieving denitrification. In addition, the composite carbon source additives in the present application can adjust the carbon-nitrogen ratio (C / N). The carbon-nitrogen ratio of many wastewaters is low, which is insufficient to support the denitrification reaction. By adding an external carbon source, the C / N ratio in the wastewater can be increased, thereby promoting denitrification.

[0065] The removal rates of NO3 - -N and NO2 - -N in Comparative Examples 1 and 2 were poor, which shows that the polyvinyl alcohol derivative and the functional filler can enhance the denitrification effect of the composite carbon source additives and improve the wastewater treatment effect.

[0066] The above embodiments are only preferred embodiments of the present application, and cannot be used to limit the scope of protection of the present application. Any non-essential changes and substitutions made by those skilled in the art on the basis of the present application are within the scope of protection of the present application.

Claims

1. A method for preparing a composite carbon source additive, characterized in that: The method comprises the following steps: weighing, by weight, 30-40 parts of a composite carbon source additive: bagasse, 8-12 parts of a polyvinyl alcohol derivative, 2-4 parts of a functional filler, 5-8 parts of potassium citrate, and 5-8 parts of sodium pyruvate; The sugarcane bagasse, functional filler, potassium citrate and sodium pyruvate are dispersed in water, and a polyvinyl alcohol derivative is added thereto and mixed uniformly to obtain a mixture; the mixture is subjected to three freeze-thaw cycles, and the mixture is dried after the final thawing. The freeze-thaw cycle is as follows: the mixture is frozen at -20°C to -15°C for 18 to 24 hours; and then thawed at room temperature, which is recorded as one freeze-thaw cycle. The mass ratio of the bagasse to water is (3-4):10; The preparation process of the polyvinyl alcohol derivative is as follows: polyvinyl alcohol, 1,3,5-benzenetrisulfonic acid, triethylamine, and 4-dimethylaminopyridine are added to dichloromethane for reaction, and the reaction is carried out by filtering, washing, and drying to obtain the polyvinyl alcohol derivative; The functional filler is prepared by adding sepiolite, 1-bromoheptane, sodium carbonate and potassium iodide to dioxane, heating for reaction, filtering, washing and drying to obtain the functional filler. The preparation process of the bagasse is as follows: the waste bagasse is dried at 50° C. to a constant weight, added to a 2wt% sodium hydroxide aqueous solution and soaked for 10-12 hours, washed with water until neutral, and then dried at 50° C. to a constant weight to obtain the bagasse.

2. The method for preparing a composite carbon source additive according to claim 1, characterized in that: The mass ratio of the polyvinyl alcohol, 1,3,5-benzenetrisulfonic acid, triethylamine, 4-dimethylaminopyridine and dichloromethane is 1:(3-4):(3-3.5):(0.2-0.3):

50.

3. The method for preparing a composite carbon source additive according to claim 1, characterized in that: In the preparation process of the polyvinyl alcohol derivative, the reaction time is 8 to 12 hours.

4. The method for preparing a composite carbon source additive according to claim 1, characterized in that: The mass ratio of the sepiolite, 1-bromoheptane, sodium carbonate, potassium iodide and dioxane is 3: (1-2): (2-4): (0.1-0.2):

80.

5. The method for preparing a composite carbon source additive according to claim 1, characterized in that: During the preparation of the functional filler, the heating reaction temperature is 90-100° C. and the time is 3-5 hours.

6. The method for preparing a composite carbon source additive according to claim 1, characterized in that: The usage ratio of the waste bagasse to the sodium hydroxide aqueous solution is 0.05-0.10 g:1 mL.

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