Degradable carbon source, preparation method and application thereof

Abstract

The application discloses a degradable carbon source and a preparation method and application thereof, and belongs to the technical field of water treatment. The preparation method comprises the following steps: adding hyperbranched quaternary ammonium salt polymer and zeolite into water, setting the temperature to 45-50 DEG C, stirring for 3h, removing water through reduced-pressure concentration, and obtaining a solid carrier; crushing and uniformly mixing high-density polyethylene, degradable polymer, plant fiber and the solid carrier, and extruding into a shape in an injection molding machine to obtain the degradable carbon source. The solid carbon source with slow-release effect is selected, various auxiliary materials are added in the high-density polyethylene, the hydrophilicity, biological affinity and positive electricity of the carbon source are improved, the adhesion effect between microorganisms and the carbon source is improved, the solid carbon source serves as a biofilm carrier for the growth of microorganisms, the problem that liquid carbon source addition is prone to overaddition is solved, secondary pollution and sludge bulking are reduced, and the denitrification performance is improved.

Description

TECHNICAL FIELD

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

[0002] In order to alleviate and control the eutrophication of water bodies, most sewage treatment plants have the characteristics of low carbon and relatively high nitrogen and phosphorus. When the content of organic matter is too low, the conventional denitrification process cannot meet the demand for carbon source in the anoxic denitrification stage. The insufficient supply of carbon source in the denitrification process will reduce the denitrification speed, and the denitrification bacteria will utilize the endogenous protoplasm for endogenous denitrification, thereby reducing the activity and quantity of the denitrification bacteria, and causing the denitrification to weaken or even stop, which greatly affects the denitrification effect of the sewage treatment plant.

[0003] The conventional carbon sources include starch, methanol, sodium acetate and industrial glucose. The high-molecular sugar such as starch needs to be converted into small-molecule organic acids such as acetic acid and formic acid to be utilized. Although methanol is a fast and easy-to-degrade organic matter, it also needs to be converted into low-molecular organic acids such as acetic acid to be utilized by microorganisms. The defects of sodium acetate and industrial glucose as carbon sources mainly lie in that the dosage is difficult to control, and secondary pollution and sludge bulking are easily caused. The treatment cost of sludge is high, which increases the cost of sewage treatment. SUMMARY

[0004] The application aims to provide a degradable carbon source and a preparation method and application thereof, so as to solve the problems of secondary pollution and sludge bulking caused by the carbon source.

[0005] The object of the application can be achieved by the following technical solutions.

[0006] A preparation method of a degradable carbon source comprises the following steps:

[0007] The hyperbranched quaternary ammonium salt polymer and zeolite are added into water, the temperature is set to 45-50 DEG C, and stirring is performed for 3h. After water is removed by reduced pressure concentration, a solid carrier is obtained. The hyperbranched quaternary ammonium salt polymer is selected as a raw material. The hydrogen in the amino group in the structure of the hyperbranched quaternary ammonium salt polymer forms a hydrogen bond with Si-O on the structure of the zeolite. The hyperbranched quaternary ammonium salt polymer is adsorbed and grafted on the zeolite, so that the solid carrier is obtained. The zeolite is an inorganic particle. Since there are hydroxyl groups on the surface, the hydrogen bonds are easily formed, so that the interparticle force is large, the agglomeration force is strong, and the agglomeration is easily formed. The hyperbranched quaternary ammonium salt polymer contains end amino groups, imine groups and cationic quaternary ammonium salt bonds. The solubility of the hyperbranched quaternary ammonium salt polymer is better than that of the conventional quaternary ammonium salt polymer. After the hyperbranched quaternary ammonium salt polymer is adsorbed and grafted, the problem that the zeolite is easily agglomerated in the polymer is improved.

[0008] High-density polyethylene, degradable polymer, plant fiber and solid carrier are crushed and mixed uniformly, and then extruded in an injection molding machine to obtain a degradable carbon source.

[0009] As a further scheme of the present application, the hyperbranched quaternary ammonium salt polymer is prepared by the following steps:

[0010] Under the condition of nitrogen protection and ice water bath, a mixture of methyl acrylate and methanol is added dropwise into triethylenediamine, the ice water bath is removed after the addition is completed, the methanol is removed under reduced pressure after the reaction is stirred for 4h, the temperature is increased to 150 DEG C, and the reaction is continued under reduced pressure for 4h to obtain the hyperbranched polyamide; the dosage ratio of triethylenediamine, methyl acrylate and methanol is 5mL:4mL:10mL.

[0011] The hyperbranched polyamide and water are stirred and mixed, then 2,3-epoxypropyltrimethylammonium chloride is added, and the reaction is stirred for 5min under the condition of 80 DEG C, then acetone is added for precipitation after the reaction is completed, and the hyperbranched quaternary ammonium salt polymer is separated; the dosage ratio of the hyperbranched polyamide, 2,3-epoxypropyltrimethylammonium chloride and water is 10g:5g:100mL.

[0012] As a further scheme of the present application, the weight ratio of the hyperbranched quaternary ammonium salt polymer and the zeolite is 1:1-2; and the diameter of the zeolite is <10mu m.

[0013] As a further scheme of the present application, the high-density polyethylene is 75-80 parts by weight, the degradable polymer is 10-20 parts by weight, the plant fiber is 10-12 parts by weight, and the solid carrier is 2-3 parts by weight.

[0014] As a further scheme of the present application, the degradable polymer is one of polybutylene succinate, polycaprolactone and polylactic acid.

[0015] As a further scheme of the present application, the size of the plant fiber is less than 100 mesh.

[0016] As a further scheme of the present application, the plant fiber is one of bamboo powder, corn straw powder, wheat straw powder and peanut straw.

[0017] As a further scheme of the present application, the high-density polyethylene is 5000S, and the melt flow rate is 0.9g / 10min.

[0018] A degradable carbon source prepared according to the preparation method has a diameter of 0.3±0.1cm and a length of 2.0±0.1cm.

[0019] The application discloses a degradable carbon source and application thereof in sewage treatment.

[0020] The application has the following beneficial effects:

[0021] In order to improve the problems of secondary pollution and sludge expansion caused by carbon source, the solid carbon source with slow-release effect is selected, various auxiliary materials are added in high-density polyethylene, the hydrophilicity, biological affinity and positive electricity of the carbon source are improved, the adhesion effect between microorganisms and the carbon source is improved, the solid carbon source is used as a biological membrane carrier for microbial growth, the problem of over-dosage of liquid carbon source is solved, the secondary pollution and sludge expansion are reduced, and the denitrification performance is improved.

[0022] In the application, the hyperbranched quaternary ammonium salt polymer and zeolite are used to prepare a solid carrier, the problem of easy agglomeration of the zeolite in the polymer matrix is improved, the dispersibility of the solid carrier in raw materials such as high-density polyethylene, degradable polymer and plant fiber is improved, the adhesion of microorganisms is uniform, and the denitrification is better; the surface of the microorganism is negatively charged, and when the microorganism is in contact with the degradable carbon source with positive charge, the microorganism is attracted, the amount of the enriched biological membrane is increased, and the removal rate of pollutants is improved.

[0023] The hyperbranched quaternary ammonium salt polymer in the added solid carrier forms a cavity with a branched structure, has the function of coating free radicals, can prevent the solid carbon source from aging, improves the stability of the solid carbon source skeleton, is convenient for the adhesion and biofilm formation of microbial growth, the strain is adapted quickly, the denitrification effect is good, and the microorganism is better for denitrification reaction. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0025] Embodiment 1

[0026] A preparation method of a degradable carbon source, comprising the following steps:

[0027] Under the conditions of nitrogen protection and ice water bath, a mixture of methyl acrylate and methanol is added dropwise into triethylenediamine, the ice water bath is removed after the addition is completed, the reaction is stirred for 4h, the methanol is removed under reduced pressure, the temperature is increased to 150 DEG C, and the reaction is continued under reduced pressure for 4h to obtain a hyperbranched polyamide; the dosage ratio of triethylenediamine, methyl acrylate and methanol is 5mL:4mL:10mL;

[0028] The hyperbranched polyamide and water are mixed by stirring, then 2,3-epoxypropyl trimethyl ammonium chloride is added, and the reaction is stirred at 80°C for 5 minutes. After the reaction is completed, acetone is added for precipitation, and the hyperbranched quaternary ammonium salt polymer is separated. The ratio of the hyperbranched polyamide, 2,3-epoxypropyl trimethyl ammonium chloride and water is 10g:5g:100mL. The hyperbranched quaternary ammonium salt polymer and zeolite are added to water, the temperature is set to 45°C, and the mixture is stirred for 3 hours. After water is removed by reduced pressure concentration, the solid phase carrier is obtained. The weight ratio of the hyperbranched quaternary ammonium salt polymer and zeolite is 1:1. The diameter of the zeolite is less than 10μm.

[0029] According to weight parts, 75 parts of high-density polyethylene (high-density polyethylene: 5000S, melt flow rate 0.9g / 10min), 10 parts of degradable polymer, 10 parts of plant fiber and 2 parts of solid phase carrier are crushed and uniformly mixed, and then extruded in an injection molding machine to obtain a degradable carbon source. The degradable polymer is polybutylene succinate; the plant fiber is corn straw powder; the size particle diameter is less than 100 mesh.

[0030] Example 2

[0031] A preparation method of a degradable carbon source includes the following steps:

[0032] Under the conditions of nitrogen protection and ice water bath, a mixture of methyl acrylate and methanol is added dropwise to triethylenediamine. After the addition is completed, the ice water bath is removed, and the reaction is stirred for 4 hours. Then, methanol is removed by reduced pressure. The temperature is increased to 150°C, and the reaction is continued for 4 hours to obtain a hyperbranched polyamide. The ratio of triethylenediamine, methyl acrylate and methanol is 5mL:4mL:10mL.

[0033] The hyperbranched polyamide and water are mixed by stirring, then 2,3-epoxypropyl trimethyl ammonium chloride is added, and the reaction is stirred at 80°C for 5 minutes. After the reaction is completed, acetone is added for precipitation, and the hyperbranched quaternary ammonium salt polymer is separated. The ratio of the hyperbranched polyamide, 2,3-epoxypropyl trimethyl ammonium chloride and water is 10g:5g:100mL. The hyperbranched quaternary ammonium salt polymer and zeolite are added to water, the temperature is set to 45°C, and the mixture is stirred for 3 hours. After water is removed by reduced pressure concentration, the solid phase carrier is obtained. The weight ratio of the hyperbranched quaternary ammonium salt polymer and zeolite is 1:1. The diameter of the zeolite is less than 10μm.

[0034] According to weight parts, 75 parts of high-density polyethylene (high-density polyethylene: 5000S, melt flow rate 0.9g / 10min), 10 parts of degradable polymer, 10 parts of plant fiber and 2 parts of solid phase carrier are crushed and uniformly mixed, and then extruded in an injection molding machine to obtain a degradable carbon source. The degradable polymer is polybutylene succinate; the plant fiber is corn straw powder; the size particle diameter is less than 100 mesh.

[0035] Example 3

[0036] A preparation method of the degradable carbon source comprises the following steps:

[0037] Under the conditions of nitrogen protection and ice water bath, a mixture of methyl acrylate and methanol is added dropwise into triethylenediamine, the ice water bath is removed after the addition, the reaction is stirred for 4 hours, methanol is removed under reduced pressure, the temperature is increased to 150 DEG C, and the reaction is continued under reduced pressure for 4 hours to obtain the hyperbranched polyamide; the dosage ratio of triethylenediamine, methyl acrylate and methanol is 5 mL:4 mL:10 mL;

[0038] The hyperbranched polyamide and water are stirred and mixed, then 2,3-epoxypropyltrimethylammonium chloride is added, the reaction is stirred for 5 minutes at a temperature of 80 DEG C, after the reaction is completed, acetone is added for precipitation, and the hyperbranched quaternary ammonium salt polymer is separated; the dosage ratio of the hyperbranched polyamide, 2,3-epoxypropyltrimethylammonium chloride and water is 10 g:5 g:100 mL. The hyperbranched quaternary ammonium salt polymer and zeolite are added into water, the temperature is set to 50 DEG C, and the stirring is continued for 3 hours, then water is removed through reduced pressure concentration to obtain the solid carrier; the weight ratio of the hyperbranched quaternary ammonium salt polymer and zeolite is 1:2; the diameter of the zeolite is less than 10 μm.

[0039] According to the weight parts, 80 parts of high-density polyethylene (high-density polyethylene: 5000S, melt flow rate 0.9 g / 10 min), 20 parts of degradable polymer, 12 parts of plant fiber and 3 parts of solid carrier are crushed and uniformly mixed, then extrusion molding is carried out in an injection molding machine to obtain a degradable carbon source; the degradable polymer is polybutylene succinate; the plant fiber is bamboo powder with a size particle diameter less than 100 mesh.

[0040] Example 4

[0041] In this example, compared with Example 2, the degradable polymer is replaced by polycaprolactone, and the rest of the raw materials and the preparation process remain the same as those of Example 2.

[0042] Example 5

[0043] In this example, compared with Example 2, the degradable polymer is replaced by polylactic acid, and the rest of the raw materials and the preparation process remain the same as those of Example 2.

[0044] Comparative Example 1

[0045] In this comparative example, compared with Example 2, the hyperbranched quaternary ammonium salt is replaced by a conventional quaternary ammonium salt polymer, and the rest of the raw materials and the preparation process remain the same as those of Example 2. In this comparative example, polyquaternary ammonium salt-10 is selected.

[0046] Comparative Example 2

[0047] The comparative example is compared with example 2, and the zeolite is not treated, and the remaining raw materials and preparation process are the same as those of example 2.

[0048] Performance tests are performed on examples 1-5 and comparative examples 1-2;

[0049] The contact angle of the prepared degradable carbon source is tested; water and dichloromethane are used for testing, respectively; and the test results are shown in Table 1:

[0050] Table 1

[0051] Item Water contact angle / ° Formamide contact angle / ° Dichloromethane contact angle / ° Zeta potential / mv Example 1 85.48±1.34 58.41±1.42 54.35±1.77 13.12±1.25 Example 2 84.16±1.25 58.38±1.36 54.27±1.52 13.16±1.39 Example 3 84.52±1.64 58.36±1.79 54.68±1.95 13.15±1.41 Example 4 86.23±1.54 58.41±1.96 54.20±1.65 13.19±1.58 Example 5 85.36±1.87 58.65±1.20 54.54±1.57 13.11±1.33 Comparative Example 1 87.49±1.24 60.64±1.68 56.92±1.36 12.15±1.14 Comparative Example 2 95.55±1.92 74.21±1.21 57.95±1.74 -37.1±1.31

[0052] From the test results, it can be seen that the degradable carbon source prepared in the application has better amphiphilicity, the Zeta potential after treatment becomes positive, and can better adsorb microorganisms; and the performance of the carbon source is stable, and secondary pollution is not easy to occur.

[0053] NO3 - -N removal rate: samples prepared in example 2 and comparative examples 1-2 are tested, artificial configuration simulation wastewater (50mg / L NO3 - -N, 1mg / L TP) and active sludge with a final concentration of 800mg / L are used. The flask is placed in a shaking incubator set at 80r / min and 25℃, and water samples are taken every 24h for COD, NO3 - -N and NO2 - -N concentration determination;

[0054] NO3 - -N is determined by ultraviolet spectrophotometry; NO2 - -N is determined by N-(1-naphthyl)-ethylenediamine photometry; and COD is determined by potassium dichromate method.

[0055] NO3 - -N removal rate calculation formula: NRR=100% x (NO 3(Nin) -NO 3(Nef) -NO 2(Nef) ) / NO 3(Nin)

[0056] In the formula, NO 3(Nin) , NO 3(Nef) are the influent and effluent NO3 - -N concentrations, mg / L; and NO 2(Nef) is the effluent NO2 - -N concentration, mg / L.

[0057] The effluent COD concentration (mg·L -1 ) is shown in Table 2:

[0058] Table 2

[0059] Days Example 2 Comparative Example 1 Comparative Example 2 2 125 171 127 4 85 165 71 6 54 123 56 8 50 118 60 10 48 110 53 12 55 124 43

[0060] NO3 - The -N removal rate results are shown in Table 3:

[0061] Table 3

[0062] Days Example 2 Comparative Example 1 Comparative Example 2 2 98.2％ 97.9％ 97.4％ 4 98.6％ 98.1％ 96.3％ 6 99.5％ 97.6％ 80.4％ 8 98.7％ 98.4％ 79.6％ 10 98.4％ 97.6％ 78.1％ 12 99.1％ 98.1％ 77.5％

[0063] From the test results, it can be seen that the degradable carbon source NO3 - The -N removal rate is higher, and the denitrification effect is stable. The reason may be that the dispersibility of the solid carrier is better, which is more conducive to the contact of microorganisms on the one hand, the surface performance of the material is more uniform, the reaction process is more uniform, on the other hand, the cavity formed by the hyperbranched structure is more conducive to the slow-release process, the effluent COD concentration is low, and there is no accumulation, and the denitrification effect is good.

[0064] It should be noted that in this paper, relational terms such as first and second are used merely to distinguish one entity or action from another, without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus including a series of elements includes not only those elements, but also other elements not explicitly listed, or inherent to such a process, method, article or apparatus.

[0065] Although embodiments of the present application have been shown and described, it will be understood by those having ordinary skill in the art that various changes, modifications, alternatives and variations can be made thereto without departing from the principles and spirit of the application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a degradable carbon source, characterized by, It comprises the following steps: The hyperbranched quaternary ammonium salt polymer and the zeolite are added into water, the temperature is set to 45-50℃, stirring for 3h, and water is removed by vacuum concentration to obtain a solid carrier; the hyperbranched quaternary ammonium salt polymer is prepared by the following steps: stirring and mixing the hyperbranched polyamide and water, then adding 2,3-epoxypropyl trimethyl ammonium chloride, stirring at a temperature of 80℃ for 5min, after the reaction is completed, adding acetone to precipitate, and separating to obtain the hyperbranched quaternary ammonium salt polymer; the dosage ratio of the hyperbranched polyamide, 2,3-epoxypropyl trimethyl ammonium chloride and water is 10g:5g:100mL; the weight ratio of the hyperbranched quaternary ammonium salt polymer and the zeolite is 1:1-2; The high-density polyethylene, the degradable polymer, the plant fiber and the solid carrier are crushed and uniformly mixed, extruded in an injection molding machine to obtain a degradable carbon source.

2. The method for preparing a biodegradable carbon source according to claim 1, characterized in that, The diameter of the zeolite is less than 10μm.

3. The method for preparing a biodegradable carbon source according to claim 1, characterized in that, According to weight parts: high-density polyethylene 75-80 parts, degradable polymer 10-20 parts, plant fiber 10-12 parts and solid carrier 2-3 parts.

4. The method for preparing a biodegradable carbon source according to claim 1, characterized in that, The degradable polymer is one of polybutylene succinate, polycaprolactone and polylactic acid.

5. The method for preparing a biodegradable carbon source according to claim 1, characterized in that, The size of the plant fiber is less than 100 mesh.

6. The method for preparing a biodegradable carbon source according to claim 1, characterized in that, The plant fiber is one of bamboo powder, corn straw powder, wheat straw powder and peanut straw.

7. The method for preparing a biodegradable carbon source according to claim 1, characterized in that, The high-density polyethylene is 5000S with a melt flow rate of 0.9g / 10min.

8. A degradable carbon source, characterized in that, Prepared by the preparation method of any one of claims 1-7.

9. The application of the degradable carbon source of claim 8 in sewage treatment.