A composite carbon source for wastewater treatment and its uses

Abstract

The present invention discloses a composite carbon source for wastewater treatment and its use, relating to the technical field of wastewater treatment. The preparation process of the composite carbon source for wastewater treatment includes: S1: Collect kitchen waste, carry out oil-water separation, remove impurities such as metals and plastics, and then carry out crushing to obtain pretreated kitchen waste; S2: Adjust the water content in the treated kitchen waste to 60-80%, and then add a conditioner and an aerobic fermentation inoculant to carry out aerobic fermentation to prepare a composite carbon source for wastewater treatment; the above-mentioned conditioner includes mushroom bran or modified mushroom bran; the above-mentioned modified mushroom bran includes surfactant-modified mushroom bran. The composite carbon source provided by the present invention has a higher carbon-nitrogen ratio and a better B / C ratio, has better biodegradability, and as an external carbon source for the wastewater treatment process, can further enhance the wastewater treatment effect and significantly improve the denitrification activity of activated sludge.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a composite carbon source for wastewater treatment and its use. Background Art

[0002] With the rapid development of social economy, the excessive discharge of nutrients in domestic sewage, industrial wastewater and agricultural non-point source pollution has caused the eutrophication of surface water bodies to become increasingly serious. The research on efficient and stable sewage denitrification and phosphorus removal technologies is of great significance for improving the quality of surface water environment. By controlling the operation of activated sludge in an alternating environment of anaerobic, anoxic and aerobic, and using the metabolic action of microorganisms for enhanced biological denitrification and phosphorus removal is one of the most widely studied and applied methods at home and abroad. The performance of biological denitrification and phosphorus removal is greatly affected by the type and concentration of carbon source in sewage. Effective carbon source supply is the guarantee for maintaining the metabolism of microorganisms and the denitrification and phosphorus removal effect of the process. Since denitrifying bacteria and phosphorus-removing bacteria coexist in activated sludge, the different carbon source requirements of microorganisms in the denitrification process and the phosphorus removal process, as well as the shortage or excess of effective carbon source in sewage, all result in unsatisfactory nitrogen and phosphorus removal rates in urban sewage treatment plants. In an enhanced biological denitrification and phosphorus removal system, different carbon source types directly affect the rate and removal rate of denitrification and phosphorus removal.

[0003] Among the existing externally added carbon sources, the traditional carbon source methanol has the advantage of low price, but due to its high toxicity, inconvenient transportation and easy harm to the human body; saccharide substances such as starch must be hydrolyzed and converted into low-molecular organic substances before they can be utilized by microorganisms, reducing the sewage treatment efficiency. Among the new externally added carbon sources, carboxylate products such as sodium formate and sodium acetate have good denitrification effects, but they are relatively expensive and have a high sludge yield, increasing the problem of additional sludge treatment; amino acid products also face problems such as high price and difficult raw material acquisition. Therefore, developing a composite carbon source with significant denitrification effect, high sewage treatment efficiency, simple use and high cost performance is an urgent problem to be solved in this field. Summary of the Invention

[0004] The purpose of the present invention is to provide a composite carbon source for wastewater treatment and its use. The composite carbon source has a higher carbon-nitrogen ratio and a better B / C ratio, has better biodegradability, and as an externally added carbon source for wastewater treatment processes, can further enhance the wastewater treatment effect and significantly improve the denitrification activity of activated sludge.

[0005] The technical solution adopted by the present invention to achieve the above purpose is as follows:

[0006] A preparation process of a composite carbon source for wastewater treatment, comprising:

[0007] S1: Collect kitchen waste, perform oil-water separation, remove impurities such as metals and plastics, and then crush it to obtain pretreated kitchen waste;

[0008] S2: Adjust the water content in the pretreated food waste to 60 - 80%, then add a conditioner and an aerobic fermentation bacterium agent to perform aerobic fermentation to obtain a composite carbon source for wastewater treatment;

[0009] The above-mentioned conditioner includes mushroom bran or modified mushroom bran; among them, the modified mushroom bran includes surfactant-modified mushroom bran.

[0010] Specifically, the dry weight ratio of food waste to the conditioner is 1:0.8 - 1.2.

[0011] Specifically, the surfactant includes a cationic surfactant.

[0012] Specifically, the cationic surfactant is a novel cationic surfactant, which is obtained by preparing from 1,3-bis[3-(dimethylamino)propyl]urea, N-hydroxyethyliminodiacetic acid, and epichlorohydrin. The present invention uses 1,3-bis[3-(dimethylamino)propyl]urea, N-hydroxyethyliminodiacetic acid, and epichlorohydrin to prepare a cationic surfactant with a novel structure, and then modifies the mushroom bran, which has a beneficial effect on its pore structure, and its specific surface area, average pore diameter, and total pore volume are all improved; using it as a conditioner in combination with an aerobic fermentation bacterium agent to act on food waste can better promote the fermentation process of food waste, effectively increase the degradation rate of organic matter, improve the components and content of the obtained composite carbon source, and then significantly enhance the role of the composite carbon source as a supplementary carbon source for wastewater treatment to promote the wastewater treatment effect, and significantly improve the removal rates of COD, total nitrogen, and ammonia nitrogen in the effluent quality; at the same time, it also enhances the denitrification activity of activated sludge to a certain extent and improves the denitrification rate of activated sludge. The reason may be that using the novel cationic surfactant to improve the mushroom bran and adjust its pore structure provides a better living environment for microorganisms, and may have more excellent degradability, providing better nutritional support for the metabolism of microorganisms and better promoting the degradation performance of microorganisms on food waste.

[0013] Specifically, the preparation method of the above-mentioned novel cationic surfactant includes:

[0014] Step 1: React 1,3-bis[3-(dimethylamino)propyl]urea with epichlorohydrin to obtain intermediate M;

[0015] Step 2: React intermediate M with N-hydroxyethyliminodiacetic acid to prepare the novel cationic surfactant.

[0016] More specifically, the preparation method of the above-mentioned novel cationic surfactant has the steps as follows:

[0017] Step 1: Take 1,3-bis[3-(dimethylamino)propyl]urea and add it to the isopropanol / water mixed solvent. Heat the mixture to 55 - 65 °C, then dropwise add epichlorohydrin under stirring conditions and finish the addition within 20 - 40 min. Then keep the temperature constant and react for 5 - 8 h. Rotate and evaporate to remove the solvent, wash with acetone, and dry under vacuum to obtain intermediate M;

[0018] Step 2: Take intermediate M, add N-hydroxyethyliminodiacetic acid and sodium hydroxide, and then add the isopropanol / water mixed solvent. React at 70 - 75 °C for 6 - 8 h. Then add hydrochloric acid solution to neutralize the remaining sodium hydroxide to make the pH of the reaction system neutral. Rotate and evaporate, wash with acetone, filter, and dry under vacuum to obtain the novel cationic surfactant.

[0019] Specifically, in Step 1, the solid-liquid ratio of 1,3-bis[3-(dimethylamino)propyl]urea to the isopropanol / water mixed solvent is 0.1 - 0.2 g:1 mL; the molar ratio of epichlorohydrin to 1,3-bis[3-(dimethylamino)propyl]urea is 1.9 - 2.1:1.

[0020] Specifically, in Step 2, the molar ratio of intermediate M to N-hydroxyethyliminodiacetic acid is 1.4 - 1.6:1; the mass ratio of sodium hydroxide to N-hydroxyethyliminodiacetic acid is 0.3 - 0.4:1; the solid-liquid ratio of N-hydroxyethyliminodiacetic acid to the isopropanol / water mixed solvent is 0.15 - 0.25 g:1 mL.

[0021] Specifically, the volume ratio of isopropanol to water in the isopropanol / water mixed solvent is 2 - 3:1.

[0022] The present invention also discloses the preparation method of the above-mentioned modified fungus chaff, including:

[0023] Take the sieved and dried Auricularia auricula fungus chaff, add the novel cationic surfactant solution with a concentration of 0.06 - 0.07 M, stir evenly, place it in a constant temperature shaker at 20 - 30 °C and 140 - 160 r / min for 10 - 12 h, then rinse with deionized water 4 - 6 times, and dry at 60 - 65 °C to obtain the modified fungus chaff.

[0024] Specifically, the solid-liquid ratio of Auricularia auricula fungus chaff to the novel cationic surfactant solution is 0.04 - 0.06 g:1 mL.

[0025] Specifically, the addition amount of aerobic fermentation inoculant is 10 8 ~10 10 CFU / kg (wet weight).

[0026] Specifically, the fermentation temperature is 45 - 55 °C, and the fermentation time is 7 - 10 d.

[0027] More preferably, during the preparation process of the composite carbon source for wastewater treatment, after obtaining the supernatant, alkyl polyglycoside or its derivative is added. By adding alkyl polyglycoside or its derivative to the composite carbon source in the present invention, the carbon-nitrogen ratio of the composite carbon source can be further adjusted, the B / C ratio of the biochemical microorganism metabolism environment can be increased, a comprehensive variety of nutrients can be provided for denitrifying bacteria, and it can be utilized by microorganisms without a long hydrolysis process. When applied to the wastewater treatment process, it is extremely easy to be utilized by denitrifying bacteria, and the denitrification effect is better; at the same time, it has good applicability to water quality sludge and flora, and further promotes the denitrification rate of activated sludge.

[0028] Further, the addition amount of alkyl polyglycoside or its derivative is 6-10 wt%.

[0029] It should be noted that the above-mentioned alkyl polyglycoside derivative includes an alkyl polyglycoside sulfate ester salt derivative modified by exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride.

[0030] The present invention also discloses a preparation method of the above-mentioned alkyl polyglycoside derivative, including:

[0031] Mix alkyl polyglycoside APG0810 and exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride, add p-toluenesulfonic acid as a catalyst, and raise the temperature to 120-125 °C for reaction for 2-4 h; then add sodium bisulfite and keep the temperature constant for reaction for 1-3 h, and separate and purify to obtain the alkyl polyglycoside derivative.

[0032] Specifically, the molar ratio of alkyl polyglycoside APG0810 to exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride is 1:0.9-1.1; the molar ratio of alkyl polyglycoside APG0810 to p-toluenesulfonic acid is 1:1.1-1.2; the molar ratio of alkyl polyglycoside APG0810 to sodium bisulfite is 1:0.9-1.

[0033] Another object of the present invention is to disclose a composite carbon source for wastewater treatment prepared by the above-mentioned preparation process.

[0034] Specifically, for the composite carbon source for wastewater treatment, C / N > 45, B / C > 60%, the SS content is 8000-9600 mg / L, and the TN content is 450-700 mg / L.

[0035] The present invention also discloses the application of the above-mentioned composite carbon source in water treatment.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The present invention uses 1,3-bis[3-(dimethylamino)propyl]urea, N-hydroxyethyliminodiacetic acid, and epichlorohydrin to prepare a cationic surfactant with a novel structure, and then modifies the mushroom residue, which produces beneficial changes to its pore structure; using it as a conditioner in combination with aerobic fermentation bacterial agents to act on kitchen waste can better promote the fermentation process of kitchen waste, effectively increase the degradation rate of organic matter, improve the components and contents of the prepared composite carbon source, and thus significantly enhance the role of the composite carbon source as a supplementary carbon source for wastewater treatment to promote wastewater treatment effects; at the same time, it also enhances the denitrification activity of activated sludge to a certain extent and improves the denitrification rate of activated sludge. At the same time, the present invention adds alkyl polyglycoside or its derivatives to the composite carbon source. When applied to the wastewater treatment process, it is easily utilized by denitrifying bacteria and has better denitrification effects; at the same time, it has good applicability to water quality sludge and bacterial communities, further promoting the denitrification rate of activated sludge. The composite carbon source provided by the present invention has high flexibility and can adjust the ratio between the components in the carbon source according to the needs of different microbial communities, so as to meet the requirements of different treatment scenarios and has a wider application range.

[0038] Therefore, the present invention provides a composite carbon source for wastewater treatment and its use. The composite carbon source has a higher carbon-nitrogen ratio and a better B / C ratio, has better biodegradability, and as an external carbon source for the wastewater treatment process, can further enhance the wastewater treatment effect and significantly improve the denitrification activity of activated sludge. Description of the Drawings

[0039] Figure 1 are the infrared test results of intermediate M and the novel cationic surfactant prepared in Example 1 of the present invention;

[0040] Figure 2 are the infrared test results of the alkyl polyglycoside derivative and alkyl polyglycoside prepared in Example 5 of the present invention;

[0041] Figure 3 are the test results of the degradation rate of organic matter during the fermentation and degradation process of the present invention. Detailed Embodiments

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will elaborate on each embodiment of the present invention in detail. However, those of ordinary skill in the art can understand that in each embodiment of the present invention, many technical details are provided to help readers better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented.

[0043] The aerobic fermentation bacterial agent used in the embodiments of the present invention is commercially available, purchased from Shandong Sukahan Bioengineering Co., Ltd., with the product number 1-25.

[0044] The characteristics of the kitchen waste in the embodiments of the present invention are shown in Table 1 as follows:

[0045] Table 1 Chemical properties of kitchen waste

[0046] Water content (%) pH Total organic matter (%) Total nitrogen (%) Total carbon content (%) 74.8 5.7 90.1 3.8 48.4

[0047] Example 1:

[0048] A preparation method of a composite carbon source for wastewater treatment:

[0049] S1: Collect kitchen waste, first perform oil-water separation, then remove impurities such as metals and plastics, and then crush it into a particle size of 6 cm to obtain pretreated kitchen waste;

[0050] S2: Put the pretreated kitchen waste into an aerobic fermentation device, adjust the water content in the pretreated kitchen waste to 68%, then add modified mushroom bran (the dry weight ratio of kitchen waste to modified mushroom bran is 1:0.92) and aerobic fermentation bacteria agent (the addition amount is 10 9 CFU / kg (wet weight)) for aerobic fermentation. The fermentation temperature is 50 °C, the fermentation time is 8 d, the aeration rate is 0.07 L / (min·L). Then, perform centrifugal separation on the fermented kitchen waste, adjust the centrifugal speed to 10000 r / min, and take the supernatant to obtain a composite carbon source for wastewater treatment. The C / N is 49.8, the B / C is 70.4%, the SS content is 8746 mg / L, and the TN content is 512 mg / L.

[0051] Preparation of modified mushroom bran:

[0052] Take the sieved and dried Auricularia auricula mushroom bran, add an aqueous solution of a new cationic surfactant with a concentration of 0.065 M, stir evenly, place it in a constant temperature shaker at 25 °C and 150 r / min for 12 h, then rinse it 5 times with deionized water and dry it at 60 °C to obtain modified mushroom bran. It should be noted that the solid-liquid ratio of Auricularia auricula mushroom bran to the new cationic surfactant solution is 0.05 g:1 mL.

[0053] Preparation of the new cationic surfactant:

[0054] Step 1: Take 1,3-bis[3-(dimethylamino)propyl]urea and add it to the isopropanol / water (v / v, 2.5:1) mixed solvent. Heat the mixture to 60 °C, then dropwise add epichlorohydrin under stirring conditions and finish the addition within 30 min. Then, carry out a constant-temperature reaction for 6 h. Rotate and evaporate to remove the solvent, wash with acetone, and dry under vacuum to obtain intermediate M. It should be noted that the solid-liquid ratio of 1,3-bis[3-(dimethylamino)propyl]urea to the isopropanol / water mixed solvent is 0.14 g:1 mL; the molar ratio of epichlorohydrin to 1,3-bis[3-(dimethylamino)propyl]urea is 2:1;

[0055] Step 2: Take intermediate M, add N-hydroxyethyliminodiacetic acid and sodium hydroxide, and then add the isopropanol / water (v / v, 2.5:1) mixed solvent. React at 70 °C for 7 h, then add hydrochloric acid solution to neutralize the remaining sodium hydroxide to make the pH of the reaction system neutral. Rotate and evaporate, wash with acetone, filter, and dry under vacuum to obtain the novel cationic surfactant. It should be noted that the molar ratio of intermediate M to N-hydroxyethyliminodiacetic acid is 1.5:1; the mass ratio of sodium hydroxide to N-hydroxyethyliminodiacetic acid is 0.36:1; the solid-liquid ratio of N-hydroxyethyliminodiacetic acid to the isopropanol / water mixed solvent is 0.21 g:1 mL.

[0056] Example 2:

[0057] The preparation method of a composite carbon source for wastewater treatment is different from that of Example 1: the dry weight ratio of food waste to modified mushroom bran is 1:0.8; the addition amount of aerobic fermentation inoculant is 10 8 CFU / kg (wet weight), the fermentation temperature is 46 °C, the fermentation time is 10 d, and the aeration rate is 0.05 L / (min·L); the C / N of the composite carbon source is 51.2, the B / C is 65.4%, the SS content is 9217 mg / L, and the TN content is 608 mg / L.

[0058] The preparation of modified mushroom bran is different from that of Example 1: the solid-liquid ratio of Auricularia auricula mushroom bran to the novel cationic surfactant solution is 0.04 g:1 mL; the novel cationic surfactant is prepared in this example.

[0059] The preparation of the novel cationic surfactant is different from that of Example 1: the molar ratio of epichlorohydrin to 1,3-bis[3-(dimethylamino)propyl]urea is 1.9:1; the molar ratio of intermediate M to N-hydroxyethyliminodiacetic acid is 1.4:1.

[0060] Example 3:

[0061] The preparation method of a composite carbon source for wastewater treatment is different from that of Example 1: the dry weight ratio of food waste to modified mushroom bran is 1:1.2; the addition amount of aerobic fermentation inoculant is 10 10CFU / kg (wet weight), fermentation temperature is 55 °C, fermentation time is 7 d, aeration rate is 0.05 L / (min·L); the C / N of the composite carbon source is 47.1, B / C is 72.9%, SS content is 9088 mg / L, TN content is 563 mg / L.

[0062] The preparation of the modified fungal residue is different from that in Example 1: the solid-liquid ratio of Auricularia auricula fungal residue to the novel cationic surfactant solution is 0.06 g: 1 mL; the novel cationic surfactant is prepared in this example.

[0063] The preparation of the novel cationic surfactant is different from that in Example 1: the molar ratio of epichlorohydrin to 1,3-bis[3-(dimethylamino)propyl]urea is 2.1:1; the molar ratio of intermediate M to N-hydroxyethyliminodiacetic acid is 1.6:1.

[0064] Example 4:

[0065] The preparation method of a composite carbon source for wastewater treatment is different from that in Example 1: the dry weight ratio of food waste to the modified fungal residue is 1:1.1; the addition amount of aerobic fermentation bacteria agent is 4×10 9 CFU / kg (wet weight), fermentation temperature is 53 °C, fermentation time is 9 d, aeration rate is 0.09 L / (min·L); the C / N of the composite carbon source is 49.9, B / C is 67.8%, SS content is 8863 mg / L, TN content is 475 mg / L.

[0066] The preparation of the modified fungal residue is different from that in Example 1: the solid-liquid ratio of Auricularia auricula fungal residue to the novel cationic surfactant solution is 0.045 g: 1 mL; the novel cationic surfactant is prepared in this example.

[0067] The preparation of the novel cationic surfactant is different from that in Example 1: the molar ratio of epichlorohydrin to 1,3-bis[3-(dimethylamino)propyl]urea is 2.05:1; the molar ratio of intermediate M to N-hydroxyethyliminodiacetic acid is 1.46:1.

[0068] Example 5:

[0069] A preparation method of a composite carbon source for wastewater treatment:

[0070] S1: Collect food waste, first carry out oil-water separation, then remove impurities such as metals and plastics, and then crush it into a particle size of 6 cm to obtain pretreated food waste;

[0071] S2: Put the pretreated food waste into an aerobic fermentation device, and adjust the water content in the pretreated food waste to 68%, then add the modified fungal residue (the dry weight ratio of food waste to the modified fungal residue is 1:0.92) and the aerobic fermentation bacteria agent (the addition amount is 109 Perform aerobic fermentation at CFU / kg (wet weight), with a fermentation temperature of 50 °C, a fermentation time of 8 d, and an aeration rate of 0.07 L / (min·L). After that, centrifuge the fermented food waste, adjust the centrifuge speed to 10,000 r / min, take the supernatant, add an alkyl polyglycoside derivative with a concentration of 8.4 wt%, and stir evenly to obtain a composite carbon source for wastewater treatment.

[0072] The preparation of the modified fungus bran is the same as that in Example 1.

[0073] The preparation of the novel cationic surfactant is the same as that in Example 1.

[0074] Preparation of the alkyl polyglycoside derivative:

[0075] Mix alkyl polyglycoside APG0810 and exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride, add p-toluenesulfonic acid as a catalyst, and raise the temperature to 124 °C for reaction for 3 h; then add sodium bisulfite and react at a constant temperature for 2 h, and separate and purify to obtain the alkyl polyglycoside derivative; it should be noted that the molar ratio of alkyl polyglycoside APG0810 to exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride is 1:1; the molar ratio of alkyl polyglycoside APG0810 to p-toluenesulfonic acid is 1:1.16; the molar ratio of alkyl polyglycoside APG0810 to sodium bisulfite is 1:0.94.

[0076] Example 6:

[0077] The preparation method of a composite carbon source for wastewater treatment is different from that in Example 5: use an equal molar amount of alkyl polyglycoside to replace the alkyl polyglycoside derivative.

[0078] The preparation of the modified fungus bran is the same as that in Example 5.

[0079] The preparation of the novel cationic surfactant is the same as that in Example 5.

[0080] Example 7:

[0081] The preparation method of a composite carbon source for wastewater treatment is different from that in Example 5: use fungus bran to replace the modified fungus bran.

[0082] The preparation of the alkyl polyglycoside derivative is the same as that in Example 5.

[0083] Example 8:

[0084] The preparation method of a composite carbon source for wastewater treatment is different from that in Example 1: use fungus bran to replace the modified fungus bran.

[0085] Example 9:

[0086] The preparation method of a composite carbon source for wastewater treatment is different from that of Example 1 in that the modified fungal residue is prepared in this example.

[0087] The preparation of the modified fungal residue is different from that of Example 1 in that octadecylamine polyoxyethylene ether bisquaternary ammonium salt is used to replace the novel cationic surfactant.

[0088] Test Example 1:

[0089] Infrared characterization

[0090] The sample is mixed and ground with potassium bromide, pressed into a tablet, and then scanned and tested with an infrared spectrometer. Test parameters: wavenumber range 500 - 4000 cm -1 .

[0091] The above tests are carried out on the intermediate M prepared in Example 1 and the novel cationic surfactant, and the results are as Figure 1 shown. It can be analyzed from the figure that in the infrared spectrum curve of intermediate M, characteristic absorption peaks of N - H bonds appear near 3130 cm -1 , characteristic absorption peaks of methylene appear in the range of 3000 cm -1 - 2800 cm -1 , characteristic absorption peaks of amide groups appear near 1680 cm -1 , 1543 cm -1 , characteristic absorption peaks of C - N bonds appear near 1268 cm -1 , and characteristic absorption peaks of epoxy groups appear near 910 cm -1 . The above results indicate that the intermediate M in Example 1 was successfully prepared. In the infrared test spectrum of the novel cationic surfactant, characteristic absorption peaks of - OH appear in the range of 3500 cm -1 - 3300 cm -1 , a characteristic absorption peak of C = O bond in the carboxylic acid group appears near 1720 cm -1 , and the characteristic absorption peak of epoxy group near 910 cm -1 disappears. The above results indicate that the novel cationic surfactant in Example 1 was successfully prepared.

[0092] The above tests are carried out on the alkyl glycoside derivative and alkyl glycoside prepared in Example 5, and the results are as Figure 2 shown. It can be analyzed from the figure that compared with the infrared spectrum curve of alkyl glycoside, in the infrared test spectrum of the alkyl glycoside derivative prepared in Example 5, a characteristic absorption peak of C = O bond appears near 1688 cm -1 , and a characteristic absorption peak of C = C bond appears near 1630 cm -1 . The above results indicate that the alkyl glycoside derivative in Example 5 was successfully prepared.

[0093] Structural Characterization of Modified Mushroom Substrate Residue

[0094] BET Analysis

[0095] The test samples were degassed with nitrogen at 423 K for 5 h, and a surface area analyzer was used to detect the specific surface area, pore volume, and pore diameter.

[0096] The above tests were performed on the original mushroom substrate residue and the modified mushroom substrate residues prepared in Examples 1-4 and Example 9. The results are shown in Table 2:

[0097] Table 2 Test Results of Structural Characterization

[0098] Sample <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Total pore volume (cm 3 / g)]]> Average pore size (Å) Example 1 58.67 0.078 54.67 Example 2 57.54 0.077 54.45 Example 3 58.26 0.078 54.73 Example 4 58.11 0.079 54.09 Example 9 55.38 0.064 51.91 Original mushroom residue 49.43 0.051 47.35

[0099] It can be seen from the data analysis in Table 2 that the specific surface area, total pore volume, and average pore diameter of the modified mushroom substrate residue prepared in Example 1 are higher than those of the original mushroom substrate residue, and also higher than those of Example 9. Moreover, the effects of Examples 2-4 are equivalent to those of Example 1, indicating that the use of the novel cationic surfactant prepared by the present invention to modify the Auricularia auricula mushroom substrate residue can effectively improve the pore structure of the modified mushroom substrate residue, significantly increase its specific surface area, and further increase the average pore diameter and total pore volume, enabling more effective utilization of more adsorption sites during the adsorption process and enhancing the adsorption performance.

[0100] Test Example 2:

[0101] Determination of Organic Matter Degradation Performance

[0102] Test method: During the fermentation of kitchen waste, all materials were weighed every 12 h, and the organic matter degradation rate was calculated using the following formula:

[0103] Organic matter degradation rate = (M0 - M t ) / M × 100%

[0104] In the formula, M0 represents the volatile solid content of the materials, aerobic fermentation inoculum, and conditioner at the initial time, g; M t represents the volatile solid content of the materials, aerobic fermentation inoculum, and conditioner at any time, g; M represents the volatile solid content of the materials at the initial time. Among them, the volatile solid content was determined by the muffle furnace ignition method at 550 °C.

[0105] The above tests were performed on the fermentation processes of Examples 1-4 and Example 8. The results are as Figure 3 shown. It can be seen from the analysis of the figure that the organic matter degradation rate during the fermentation process of Example 1 is significantly higher than that of Example 8, and the effects of Examples 2-4 are equivalent to those of Example 1, indicating that the use of the novel cationic surfactant prepared by the present invention to modify the Auricularia auricula mushroom substrate residue and compound it with an aerobic fermentation agent for application in the fermentation of kitchen waste can effectively promote the degradation effect of kitchen waste and significantly increase the organic matter degradation rate.

[0106] Test Example 3:

[0107] Investigation on Sewage Treatment Effect

[0108] Treatment method: The sewage to be treated first passes through a sedimentation tank, and colloids and fine suspended solids are removed under the action of a coagulant. Then it enters an aerated biological filter for carbonization and nitrification reactions. Then it enters a denitrification filter, and a composite carbon source sample (the addition amount is 250 mg / L) is added to assist in the denitrification reaction. Then it successively enters a sand filter and a catalytic oxidation tank to obtain purified water. The sludge concentration during operation is 3000 - 5000 mg / L.

[0109] Index determination: The determination of the COD content is carried out according to the standard of the dichromate method for determining the chemical oxygen demand COD of water quality specified in HJ / T 828; the determination of the total nitrogen content is carried out according to the standard of the gas-phase molecular absorption spectrometry method for determining the total nitrogen content of water quality specified in HJ / T 199; the determination of the ammonia nitrogen content is carried out according to the standard of the continuous flow - salicylic acid spectrophotometry method for determining the ammonia nitrogen content of water quality specified in HJ / T 665.

[0110] The physical and chemical indexes of the test sewage are shown in Table 3:

[0111] Table 3 Physical and Chemical Indexes of Sewage

[0112] pH COD (mg / L) Total nitrogen content (mg / L) Ammonia nitrogen content (mg / L) 6.8 178.56 42.54 37.03

[0113] The above tests were carried out on the composite carbon sources prepared in Examples 1 - 9, and the results are shown in Table 4:

[0114] Table 4 Test Results of Effluent Water Quality

[0115] Sample COD (mg / L) Total nitrogen content (mg / L) Ammonia nitrogen content (mg / L) Example 1 15.65 9.55 1.99 Example 2 15.47 9.47 1.89 Example 3 15.71 9.68 1.95 Example 4 15.34 9.40 1.97 Example 5 9.22 5.76 0.45 Example 6 12.98 7.11 1.23 Example 7 19.36 13.34 3.82 Example 8 25.64 17.23 5.75 Example 9 18.95 13.87 3.94

[0116] From the data analysis in Table 4, it can be seen that during the sewage treatment process, adding the composite carbon source prepared in Example 1 for auxiliary treatment, the COD content, total nitrogen content, and ammonia nitrogen content in the effluent water quality are significantly lower than those in Examples 8 - 9. The effects of Examples 2 - 4 are equivalent to that of Example 1, indicating that using the novel cationic surfactant prepared from 1,3 - bis[3 - (dimethylamino)propyl]urea, N - hydroxyethyliminodiacetic acid, and epichlorohydrin to modify the mushroom residue, and applying the obtained modified mushroom residue as a conditioner in the aerobic fermentation process of food waste can obtain a composite carbon source with better components. Adding it to the sewage treatment process significantly enhances the sewage treatment effect, and the removal rates of COD, total nitrogen, and ammonia nitrogen are significantly improved. The effect of Example 5 is better than that of Example 1 and Example 6, and the effect of Example 7 is better than that of Example 8, indicating that using the alkyl glycoside derivative prepared by modifying alkyl glycoside with exo - 3,6 - epoxy - 1,2,3,6 - tetrahydrophthalic anhydride and mixing it with the food waste fermentation broth to prepare a composite carbon source and applying it to the sewage treatment process can further enhance the sewage treatment effect.

[0117] Investigation on the sludge characteristics of composite carbon source - acclimated sludge

[0118] Carry out an adaptive orthogonal denitrification experiment on the acclimated sludge in the above - mentioned sewage treatment process under the presence of different composite carbon sources:

[0119] Specific denitrification rate test

[0120] Take 1.5 L of sludge from the reactor, wash it twice with deionized water, and then make the volume up to 1.5 L; blow off the remaining dissolved oxygen in the sludge through nitrogen. Seal it when its value is less than or equal to 0.1 mg / L; then add the composite carbon source sample to adjust the COD concentration to 400 mg / L, add 60 mg / L of NO3 - N, stir, time, and take samples regularly. Centrifuge at 4℃ and 6000 r / min for 5 min, and filter the supernatant through a 0.45 - μm filter membrane. Take samples to measure the concentrations of NO3 - N (the test method is ultraviolet spectrophotometry) and NO2 - N (the determination method is N - (1 - naphthyl) - ethylenediamine photometry).

[0121] The experimental analysis adopts the electron transfer mechanism, and uses C(NO x -N)=C(NO3 - N + 0.6NO2 - N) to represent the concentration of the remaining total nitrogen in the reactor, and ignores the existence of other intermediate products. Finally, calculate the specific denitrification rate of the sludge according to the following formula:

[0122] Specific denitrification rate of sludge = d(C(NO x -N)) / (MLVSS·dt)

[0123] The test results are shown in Table 5:

[0124] Table 5 Test Results of Sludge Characteristics

[0125] Sample <![CDATA[Denitrification rate (mg NO x -N / (g MLVSS·h))]]> Example 1 8.9657 Example 5 11.0218 Example 6 9.9954 Example 7 9.8466 Example 8 7.8263 Example 9 8.3125

[0126] It can be seen from the data analysis in Table 5 that the denitrification rate of the sludge treated with the composite carbon source prepared in Example 1 is significantly higher than that of Examples 8-9, indicating that a novel cationic surfactant prepared from 1,3-bis[3-(dimethylamino)propyl]urea, N-hydroxyethyliminodiacetic acid, and epichlorohydrin is used to modify the mushroom bran, and the obtained modified mushroom bran is used as a conditioner in the aerobic fermentation process of food waste, a composite carbon source with better components can be obtained, which is more conducive to being utilized by microorganisms, maintaining a better sludge growth amount, and ensuring the activity of the acclimated sludge. The effect of Example 5 is significantly better than that of Examples 1 and 6, and the effect of Example 7 is better than that of Example 8, indicating that an alkyl glycoside derivative is prepared by modifying alkyl glycoside with exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride and compounded with the food waste fermentation broth to obtain a composite carbon source, which can further enhance its ability to be absorbed and utilized by microorganisms and enhance the sludge activity.

[0127] The conventional technologies in the above examples are the existing technologies well known to those skilled in the art, so they will not be elaborated in detail here.

[0128] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, and all should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A preparation process of a composite carbon source for wastewater treatment, comprising: S1: Collect kitchen waste, perform oil-water separation, remove impurities, and then crush it to obtain pretreated kitchen waste; S2: Adjust the water content of the pretreated kitchen waste to 60-80%, then add a conditioner and an aerobic fermentation bacterium agent for aerobic fermentation, and centrifuge to separate and take the supernatant to prepare a composite carbon source for wastewater treatment; The conditioner includes modified mushroom bran; The modified mushroom bran includes surfactant-modified mushroom bran, and the surfactant includes a cationic surfactant; the cationic surfactant is prepared from 1,3-bis[3-(dimethylamino)propyl]urea, N-hydroxyethyliminodiacetic acid, and epichlorohydrin.

2. A composite carbon source for wastewater treatment prepared by the preparation process according to claim 1.

3. The composite carbon source for wastewater treatment according to claim 2, characterized in that: The composite carbon source for wastewater treatment has a C / N > 45, B / C > 60%, an SS content of 8000-9600 mg / L, and a TN content of 450-700 mg / L.

4. The composite carbon source for wastewater treatment according to claim 2, wherein: An alkyl glucoside or its derivative is also added to the composite carbon source for wastewater treatment.

5. The composite carbon source for wastewater treatment according to claim 4, characterized in that: The addition concentration of the alkyl glucoside or its derivative is 6-10 wt%.

6. Use of the composite carbon source according to claim 2 in water treatment.

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