A composite reagent and method suitable for strengthening hydrolysis of kitchen waste to prepare carbon source

Abstract

The application discloses a kind of composite reagent and method suitable for strengthening kitchen waste hydrolysis preparation carbon source.The active ingredients of composite reagent include sodium bicarbonate, alkyl glycoside, disodium hydrogen phosphate and magnesium chloride.The composite reagent is used in the process of kitchen waste hydrolysis preparation carbon source, can eliminate or slow down hydrolysis inhibiting factor, remove the adverse factors in carbon source product, effectively improve the added value of carbon source product.The use of the reagent can effectively reduce the oil content in carbon source product by 40-45%, increase the content of small molecule organic acid by 2-3 times, the removal rate of ammonia nitrogen reaches 65-75%, the removal rate of phosphorus reaches 80-90%, which is beneficial to realize the resource treatment of kitchen waste.

Description

Technical Field

[0001] This invention relates to a reagent and method for treating kitchen waste, and particularly to a composite reagent and method suitable for enhancing the preparation of carbon sources from the hydrolysis of kitchen waste, belonging to the field of kitchen waste resource utilization technology. Background Technology

[0002] Food waste refers to leftover food from restaurants, canteens, and other similar establishments, as well as processing waste from fruits, vegetables, meat, oil, and pastries in the kitchen. Food waste is highly perishable, emitting foul odors and spreading bacteria and viruses. If not disposed of promptly, it can cause significant harm to human health and the living environment. However, due to its high COD value and high C / N ratio, food waste can serve as an excellent external carbon source, providing nutrients and electrons to denitrifying bacteria. However, due to the complex composition of food waste, its characteristics of high oil content, high ammonia nitrogen content, and high molecular weight organic matter lead to the following problems in its practical application as an external carbon source: 1. Food waste has a high oil content. Although most of the oil is removed after three-phase centrifugation, the residual oil content is still as high as 0.8% to 1%. Numerous studies have shown that oil can coat microorganisms in the fermentation system and carry them to the upper layer of the fermentation system, reducing the amount of microorganisms in the system and thus inhibiting the hydrolysis rate. Moreover, oil is difficult to degrade, and as the carbon source product enters the biochemical system, it will also inhibit the reaction of the biochemical system, causing secondary pollution; 2. Food waste... During the hydrolysis of kitchen waste to produce acid, the generation of organic acids causes the pH of the slurry to drop. When the acid accumulates to a certain concentration, it can inhibit hydrolysis, preventing further hydrolysis. Incomplete hydrolysis results in a large number of macromolecules that cannot be degraded. These macromolecules remain in the carbon source product and enter the downstream biological treatment system. The degradation of macromolecules takes time, but the residence time in the biological treatment system is insufficient, leading to incomplete degradation and ultimately resulting in high COD in the effluent. 3. As an external carbon source, kitchen waste has a high nitrogen content. Introducing it into the biological treatment system will increase the nitrogen load of the system. If the degradation is incomplete, it will also cause secondary pollution of the downstream effluent.

[0003] To address these issues, researchers have developed several agents in recent years. For example, the literature "Optimization of Deep Degreasing Scheme for Kitchen Waste Emulsion" (Deng Mengxuan et al., Science, Technology and Engineering, 20.4(2020):7) uses polyferric sulfate for demulsification to remove oil from kitchen waste, achieving good results. However, this method consumes SCOD, which is detrimental to subsequent hydrolysis. Another example is the literature "Study on Enhancing Enzymatic Hydrolysis and Acidification of Excess Sludge with Sodium Citrate" (Luo Kun et al., Journal of Environmental Science, 35.11(2015):6), which uses the cationic complexing agent sodium citrate to enhance the hydrolysis and acidification of excess sludge, achieving ideal results. However, these agents have limited functionality and narrow applicability. Therefore, there is an urgent need to find a multifunctional, widely applicable composite agent that can eliminate adverse factors and promote downstream hydrolysis. Summary of the Invention

[0004] In view of the technical problems in the preparation and use of food waste as an external carbon source, such as high oil content, high content of recalcitrant organic matter due to acid inhibition, and high nitrogen content, the first objective of this invention is to provide a composite agent suitable for enhancing the preparation of carbon sources from the hydrolysis of food waste. This composite agent, when used in the process of preparing carbon sources from the hydrolysis of food waste, can effectively slow down or eliminate hydrolysis inhibitory factors to promote downstream hydrolysis, while eliminating unfavorable factors in the carbon source product and increasing the added value of the carbon source product.

[0005] The second objective of this invention is to provide a method for preparing carbon sources by hydrolysis of kitchen waste. Using this composite agent, the oil content in the carbon source product can be effectively reduced by 40-45%, the content of small molecule organic acids can be increased by 2-3 times, and the ammonia nitrogen removal rate can reach 65-75%, and the phosphorus removal rate can reach 80-90%, which is beneficial to the resource utilization of kitchen waste.

[0006] To achieve the above-mentioned technical objectives, the present invention provides a composite agent suitable for enhancing the preparation of carbon sources from the hydrolysis of kitchen waste, the active ingredients of which include sodium bicarbonate (NaHCO3), alkyl glycoside (APG0810), disodium hydrogen phosphate (Na2HPO4), and magnesium chloride (MgCl2).

[0007] The active ingredients of the composite agent of the present invention include NaHCO3, APG0810, Na2HPO4 and MgCl2. These active ingredients have synergistic effects, which can solve the problems of single function and insignificant effect of traditional agents. The mechanism of synergistic effect of the composite agent of the present invention in the process of preparing carbon source by hydrolysis of kitchen waste is as follows: (1) The composite agent contains alkyl glycosides, which can achieve wetting reversal, penetration and dispersion on the surface of oily matrix to achieve demulsification of emulsified oily dirt, and then achieve oil removal through oil-water separation. Oil removal can alleviate the inhibition of oil on the hydrolysis of kitchen waste, promote the occurrence of hydrolysis, and also reduce the oil content of carbon source products and increase the added value of carbon source products; (2) The composite agent contains acid salts such as sodium bicarbonate and disodium hydrogen phosphate, which play a good buffering role on the pH of the solution system, and can react with VFAs and NH4 in kitchen slurry during the hydrolysis process. + -N forms a multi-component pH buffer system. Under the action of the buffer system, the pH value of the system can be kept stable. The stable growth environment is more conducive to the growth and metabolism of hydrolytic acid-producing bacteria, weakens the acid inhibition caused by the accumulation of organic acids during fermentation, and further promotes hydrolysis; (3) The compound agent contains phosphate ions and magnesium ions, and the kitchen slurry contains ammonium ions. In an alkaline environment, these three ions combine and react to generate magnesium ammonium phosphate (MgNH4PO4·6H2O), and the solubility product of magnesium ammonium phosphate is 1×10 -13 ~7.08×10 -14 The solubility in water is very low. Nitrogen and phosphorus can be recovered simultaneously through solid-liquid separation. The recovered magnesium ammonium phosphate is a slow-release fertilizer that can be used in agricultural production. (4) Alkyl glycosides are biodegradable and environmentally friendly agents. They can be used as early nutrients for hydrolytic microorganisms to enrich the microbial community. Sodium bicarbonate, as a buffer solution, can provide a stable environment for hydrolytic microorganisms to promote their growth. Other salt components can also be used as nutrients for microbial growth to promote their growth. The components in the compound agent work together to solve the problems of high oil content, high content of difficult-to-degrade organic matter, and high nitrogen content in the preparation and use of kitchen waste as an external carbon source. While improving the hydrolysis efficiency, it also enhances the added value of the carbon source product.

[0008] As a preferred embodiment, the mass ratio of NaHCO3, APG0810, Na2HPO4, and MgCl2 is (2.5–3.75):(500–750):(140–210):(165–247.5). If the amount of APG0810 is too low, the composite agent will have difficulty fully contacting the contaminants, resulting in poor oil removal efficiency. Conversely, excessively high additions do not significantly improve oil removal efficiency and will increase costs. Too high or too low a dosage of NaHCO3 is detrimental to the formation of the buffer system; its dosage depends on the acid and ammonia nitrogen content in the solution. Too high a concentration of Na2HPO4 and MgCl2 will lead to high osmotic pressure, damaging cell structure and inhibiting the growth of hydrolyzing bacteria. Too low a concentration will prevent the formation of a precipitate for nitrogen and phosphorus recovery.

[0009] As a preferred embodiment, the composite agent comprises water and active ingredients, wherein the concentration of NaHCO3 in water is 2.5–3.75 mg / mL, the concentration of APG0810 in water is 500–750 mg / mL, the concentration of Na2HPO4 in water is 140–210 mg / mL, and the concentration of MgCl in water is 165–247.5 mg / mL.

[0010] As a preferred embodiment, the pH of the composite agent is 5.5 to 6.5.

[0011] This invention provides a method for preparing a carbon source by hydrolysis of kitchen waste, comprising the following steps: 1) pre-treating kitchen waste by three-phase centrifugation to obtain kitchen waste slurry; 2) adding the composite agent to the kitchen waste slurry, stirring and reacting, allowing it to stand, and then skimming off the supernatant to obtain de-oiled slurry; 3) inoculating activated sludge into the de-oiled slurry for anaerobic hydrolysis, and allowing the hydrolysis products to precipitate under alkaline conditions, with the supernatant being the carbon source solution.

[0012] The method for preparing a carbon source from food waste via hydrolysis provided by this invention first pre-treats the food waste by centrifugation, mainly to remove most of the oil. The remaining oil content is 0.8%–1%, which is detrimental to the subsequent anaerobic hydrolysis process. By introducing a composite agent, the oil penetration and dispersion are enhanced to achieve oil-water separation, thus achieving deep oil removal. The oil-free slurry then smoothly enters the anaerobic hydrolysis process. The composite agent stabilizes the pH of the system by reacting with VFAs and NH4+ in the food waste slurry. + The -N complex forms a multi-component pH buffer system, providing a stable pH environment for the growth and metabolism of acid-producing bacteria, promoting the hydrolysis of organic acids, reducing acid inhibition caused by the accumulation of organic acids during fermentation, and after anaerobic hydrolysis, adjusting the system to an alkaline environment allows the use of PO4 introduced in the compound agent. 3- NH4+ With Mg 2+ The formation of a stable magnesium ammonium phosphate complex salt precipitate achieves the purpose of dephosphorization and deammoniation.

[0013] As a preferred embodiment, the volume ratio of the composite agent to the kitchen slurry is (2-3):100; the TS (total saline) content of the kitchen slurry is 8-12%. If the amount of composite agent added is further increased beyond this, the improvement in pollutant removal and hydrolysis enhancement is not significant, and it will increase the system cost. Furthermore, excessive addition may lead to excessively high salt content in the solution, disrupting the osmotic pressure balance inside and outside the cells, causing microorganisms to lose activity and inhibiting hydrolysis. Conversely, if the amount added is too low, the reaction molecules cannot fully contact and collide, and the reaction rate will also decrease.

[0014] As a preferred embodiment, the stirring reaction time is 30–60 min, and the stirring rate is 300–500 rpm / min. Mechanical stirring can promote the interaction between the compound agent and the kitchen slurry, improve the penetration and dispersion of oils, and enhance the oil-water separation effect. The settling time is 40–80 min.

[0015] As a preferred embodiment, the anaerobic hydrolysis is performed at a temperature of 37–38°C for 4–6 days, with intermittent stirring to assist the anaerobic hydrolysis at intervals of 0.5–1.5 h and a stirring rate of 300–500 rpm / min.

[0016] As a preferred method, the alkaline reagent for adjusting the pH is 4–6 mol / L NaOH, the pH adjustment range is 7.5–8.5, the precipitation reaction time is 30–60 min, and the standing time is 80–120 min. Under these preferred reaction conditions, the formation of magnesium ammonium phosphate complex salt precipitate can be promoted.

[0017] The method for enhancing the preparation of carbon sources from food waste through hydrolysis provided by this invention includes the following specific steps:

[0018] S1: Take the three-phase centrifuged liquid of kitchen waste, with a TS content of 8-12%; add the compound agent to the mixed slurry at a volume ratio of 2-3% of the compound agent to the kitchen waste slurry, and stir during the addition process at a stirring speed of 300-500 rpm / min to ensure that the agent is mixed evenly and in full contact with the slurry. After reacting for 30-60 minutes, let it stand for 40-80 minutes and skim off the supernatant; the formula of the compound agent is as follows: sodium bicarbonate (NaHCO3) 2.5-3.75 mg / mL, alkyl glycoside (APG0810) 500-750 mg / mL, disodium hydrogen phosphate (Na2HPO4) 140-210 mg / mL, magnesium chloride (MgCl2) 165-247.5 mg / mL, and adjust the pH to 5.5-6.5.

[0019] S2: Add inoculating sludge to the slurry at a volume ratio of 1:(3-5), and then start anaerobic hydrolysis of the food waste slurry. The hydrolysis temperature is 37-38℃ and the time is 4-6 days. During the process, the slurry is intermittently stirred. The time interval between intermittent stirring is 0.5-1.5h, and the stirring rate is 300-500rpm / min.

[0020] S3: After hydrolysis, add an alkaline reagent to the system, which is 4-6 mol / L NaOH, adjust the pH of the system to 7.5-8.5, react for 30-60 min, let stand for 60-120 min, and take the supernatant.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] The composite agent provided by this invention mainly plays a synergistic role in the process of preparing carbon sources from food waste through hydrolysis, and can bring the following beneficial effects: First, it can improve the degreasing effect of food waste slurry, eliminate the inhibition of hydrolysis by oil, promote the occurrence of hydrolysis, and at the same time reduce the oil content of downstream products, thereby increasing the added value of products; Second, it can stabilize the pH of the system during anaerobic hydrolysis by reacting with VFAs and NH4+. + The -N complex forms a multi-component pH buffer system, providing a stable pH environment for the growth and metabolism of hydrolytic acid-producing bacteria, weakening the acid inhibition caused by the accumulation of organic acids during fermentation, and promoting the anaerobic hydrolysis process; thirdly, it can realize the recovery of ammonia nitrogen and phosphorus in the system by introducing PO4. 3- and Mg 2+ Ions and NH4 +In an alkaline environment, the reaction produces a sparingly soluble precipitate, MgNH4PO4·6H2O, which is then recovered from the wastewater via solid-liquid separation. Fourthly, alkyl glycosides are biodegradable and environmentally friendly agents. They can serve as early nutrients for hydrolyzing microorganisms, enriching the microbial community. Sodium bicarbonate, as a buffer solution, provides a stable environment for the hydrolyzing microorganisms, promoting their growth. Other salt components can also serve as nutrients for microbial growth. In summary, the active components in the composite agent synergistically solve the problems of high oil content, high recalcitrant organic matter content, and high nitrogen content in the preparation and use of kitchen waste as an external carbon source, improving efficiency while enhancing the added value of the carbon source product.

[0023] The composite agent of this invention uses biodegradable organic matter and nutrients, which are harmless to the human body and environmentally friendly. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the process for using composite agents to enhance the hydrolysis of kitchen waste to prepare carbon sources in an embodiment of the present invention. Detailed Implementation

[0025] The following specific embodiments are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the claims.

[0026] The following is in conjunction with the appendix Figure 1 The present invention will be further described in detail below with reference to specific embodiments.

[0027] In the following examples and comparative examples: the food waste was a three-phase centrifugal liquid from a food waste treatment plant in Hunan Province, with a total TS content of 10%, a SCOD of 60580 mg / L, and NH4+ content of... + -N was 1223 mg / L, TP was 534 mg / L, oil content was 8216 mg / L, and VFAs were 2423 mg / L.

[0028] In the following examples and comparative examples: the inoculated activated sludge was taken from the hydrolysis sludge in the hydrolysis tank of a kitchen waste treatment plant in Hunan Province. The hydrolysis sludge was first reacted at room temperature for 24 hours, then the supernatant was skimmed off, and it was stored in a refrigerator at 4°C for later use. The sludge TS was 9%, SCOD was 64780 mg / L, and NH4 was... + -N was 1345 mg / L, TP was 534 mg / L, oil content was 7494 mg / L, and VFAs were 5457 mg / L.

[0029] In the following examples and comparative examples, a schematic diagram of the process for enhancing the hydrolysis of food waste to produce carbon sources using a composite agent is shown below. Figure 1 .

[0030] Example 1

[0031] Take the three-phase centrifuged liquid from kitchen waste and add the compound reagent (NaHCO3+APG0810+Na2HPO4+MgCl2=3mg / mL:625mg / mL:175mg / mL:206mg / mL, with water as the solvent) to the slurry at a volume ratio of 2:100. React for 30 minutes, stirring the slurry at a speed of 300 rpm / min during the reaction. Then let it stand for 60 minutes and skim off the upper layer of grease. Next, inoculated sludge was added to the slurry at a volume ratio of 1:4 to inoculated sludge, and anaerobic hydrolysis was carried out. During the reaction, the system temperature was maintained at 37.5℃ by water bath, and intermittent stirring was performed at a stirring cycle of 1 hour and a stirring rate of 300 rpm / min to ensure uniform distribution of the reagent and sufficient contact with the slurry. The hydrolysis process lasted for 6 days. After hydrolysis, an alkaline reagent was added to the system to adjust the pH to 7.5, and the system was stirred continuously for 30 minutes at the same stirring rate as above. Finally, the system was allowed to stand for 60 minutes, and the supernatant was collected.

[0032] After the reaction was completed, the supernatant was taken for index testing. The results showed that SCOD was 49234.25 mg / L and NH4+ was... + -N was 875 mg / L, TP was 106.8 mg / L, oil content was 4842.96 mg / L, and VFAs were 19693.7 mg / L. The oil removal rate was 40%, the ammonia nitrogen recovery rate was 62.68%, the phosphorus recovery rate was 80%, and the VFAs growth rate was 550%.

[0033] Example 2

[0034] The carbon source preparation process in this embodiment is the same as in Example 1 above, but the ratio of the composite reagent is as follows: (NaHCO3 + APG0810 + Na2HPO4 + MgCl2 = 3.5 mg / mL: 700 mg / mL: 196 mg / mL: 231 mg / mL, solvent is water). After the reaction is complete, the supernatant is taken for index detection. The test results show SCOD: 49976.25 mg / L, NH4+ + The concentrations of nitrogen (N) were 826.76 mg / L, total phosphorus (TP) were 93.68 mg / L, oil content was 4625.75 mg / L, and vitamin A (VFAs) were 21876.35 mg / L. The oil removal rate was 42.69%, the ammonia nitrogen recovery rate was 64.74%, the phosphorus recovery rate was 82.46%, and the VFAs growth rate was 622%.

[0035] Example 3

[0036] The carbon source preparation process in this embodiment is the same as in Example 1 above, but the hydrolysis process lasts for 4 days. After the reaction is complete, the supernatant is taken for index testing. The test results show SCOD: 42769.87 mg / L, NH4+: + -N was 875 mg / L, TP was 106.8 mg / L, oil content was 4842.96 mg / L, and VFAs were 14684.97 mg / L. The oil removal rate was 40%, the ammonia nitrogen recovery rate was 62.68%, the phosphorus recovery rate was 80%, and the VFAs growth rate was 384.68%.

[0037] Comparative Example 1

[0038] The carbon source preparation process in this embodiment is the same as in Example 1 above, but no reagents are added during the preparation process. After the reaction is complete, the supernatant is taken for index detection. The test results show that the SCOD is 45876 mg / L and the NH4+ is... + -N was 2345 mg / L, TP was 534 mg / L, oil content was 7494 mg / L, and VFAs were 8379 mg / L.

[0039] As can be seen from the examples and Comparative Example 1, directly using kitchen waste to hydrolyze carbon sources has the problems of high oil content, high nitrogen and phosphorus content, and low small molecule acid content in the carbon source products.

[0040] Comparative Example 2

[0041] The carbon source preparation process in this embodiment is the same as in Example 1 above, except that only alkyl glycoside (625 mg / mL, water as solvent) is added during the preparation process. The supernatant was analyzed, and the results showed an SCOD of 46362.7 mg / L and NH4+. + The concentrations of nitrogen (N) and phosphorus (TP) were 2345 mg / L, respectively, with an oil content of 5156.5 mg / L and VFAs of 9863.8 mg / L. The oil removal rate was 36.12%, the ammonia nitrogen recovery rate was 0%, the phosphorus recovery rate was 0%, and the VFAs growth rate was 226%.

[0042] Comparative Example 3

[0043] The carbon source preparation process in this embodiment is the same as in Example 1 above, except that only alkyl glycosides and sodium bicarbonate are added as a composite agent (NaHCO3+APG0810=3mg / mL:625mg / mL, solvent is water) during the preparation process;

[0044] The supernatant was analyzed for its parameters, and the results showed that the SCOD was 47382.7 mg / L and the NH4+ content was [missing value]. +The concentrations of nitrogen (N) and phosphorus (TP) were 2345 mg / L, respectively, with an oil content of 4978.5 mg / L and VFAs of 17863.8 mg / L. The oil removal rate was 38.32%, the ammonia nitrogen recovery rate was 0%, the phosphorus recovery rate was 0%, and the VFAs growth rate was 489.6%.

[0045] Comparative Example 4

[0046] The carbon source preparation process in this embodiment is the same as in Example 1 above, except that only sodium bicarbonate, dipotassium hydrogen phosphate and magnesium chloride composite reagent (NaHCO3+Na2HPO4+MgCl2=3mg / mL:175mg / mL:206mg / mL, solvent is water) is added during the preparation process;

[0047] The supernatant was analyzed, and the results showed that the SCOD was 44983.7 mg / L and the NH4+ content was [not specified]. + The concentrations of nitrogen (N) and phosphorus (TP) were 938 mg / L, 133.5 mg / L, 7108.3 mg / L of oil, and 16833.5 mg / L of vitamin A (VFAs). The oil removal rate was 11.93%, the ammonia nitrogen recovery rate was 60%, the phosphorus recovery rate was 75%, and the VFAs growth rate was 455.6%.

[0048] Comparative Example 5

[0049] The carbon source preparation process in this embodiment is the same as in Example 1 above. The only difference is that only a composite reagent of alkyl glycoside, dipotassium hydrogen phosphate and magnesium chloride (APG0810+Na2HPO4+MgCl2=625mg / mL:175mg / mL:206mg / mL, with water as the solvent) is added during the preparation process.

[0050] The supernatant was analyzed for its parameters, and the results showed that the SCOD was 45863.7 mg / L and the NH4+ was... + The concentrations of nitrogen (N) and phosphorus (TP) were 938 mg / L, 133.5 mg / L, 5232.5 mg / L of oil, and 10683.5 mg / L of vitamin A and vitamins (VFAs). The oil removal rate was 35.17%, the ammonia nitrogen recovery rate was 60%, the phosphorus recovery rate was 75%, and the VFAs growth rate was 252.61%.

[0051] In summary, compared to single-function enhancers, the reagents of this invention are more comprehensive in function and have a wider range of applications. The compound reagents, through formulation, synergistically solve the problems encountered in the process of preparing carbon sources from food waste, such as high oil content, high nitrogen and phosphorus content, and low levels of small-molecule acids. This better ensures that the carbon source products from the hydrolysis of food waste meet the process requirements for use as an external carbon source.

Claims

1. A method for preparing a carbon source from kitchen waste by hydrolysis, characterized in that: The method comprises the following steps: 1) pretreating the kitchen waste by three-phase centrifugation to obtain kitchen slurry; 2) adding a composite reagent to the kitchen slurry, stirring and reacting, then standing and treating, and removing the supernatant to obtain a deoiled slurry; 3) inoculating activated sludge into the deoiled slurry, performing anaerobic hydrolysis, and precipitating the hydrolysis product under alkaline conditions to obtain a carbon source solution; the temperature of the anaerobic hydrolysis is 37-38℃; The composite reagent comprises active ingredients and water, and the active ingredients comprise sodium bicarbonate, alkyl glycoside, disodium hydrogen phosphate and magnesium chloride; the mass ratio of the sodium bicarbonate, alkyl glycoside, disodium hydrogen phosphate and magnesium chloride is (2.5-3.75):(500-750):(140-210):(165-247.5); The concentration of the sodium bicarbonate in the water is 2.5-3.75 mg / mL, the concentration of the alkyl glycoside in the water is 500-750 mg / mL, the concentration of the disodium hydrogen phosphate in the water is 140-210 mg / mL, and the concentration of the magnesium chloride in the water is 165-247.5 mg / mL.

2. The method for preparing carbon source by hydrolysis of kitchen waste according to claim 1, characterized in that: The volume ratio of the composite reagent to the kitchen slurry is (2-3):100; the TS mass content of the kitchen slurry is 8-12%.

3. The method for preparing a carbon source by hydrolysis of kitchen waste according to claim 1, characterized in that: The stirring time is 30-60 min, and the stirring rate is 300-500 rpm / min.

4. The method for preparing carbon source by hydrolyzing kitchen waste according to claim 1, characterized in that: The standing time is 40-80 min. 5.The method of claim 1, wherein the carbon source is prepared by hydrolysis of the kitchen waste. The anaerobic hydrolysis time is 4-6 d, and the anaerobic hydrolysis is assisted by intermittent stirring with a time interval of 0.5-1.5 h and a stirring rate of 300-500 rpm / min. 6.The method of preparing carbon source from kitchen waste by hydrolysis according to claim 1, characterized in that: The precipitation reaction is performed under the following conditions: the pH value is controlled at 7.5-8.5, and the precipitation reaction time is 30-60 min.

7. The method for preparing carbon source from kitchen waste by hydrolysis according to claim 1, characterized in that: The pH of the composite reagent is 5.5-6.5.

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