A method for enhancing anaerobic digestion of organic solid waste using polyphenol iron complex

Abstract

The present invention discloses a method for strengthening the anaerobic digestion of organic solid waste by using a polyphenol iron complex, which belongs to the technical field of anaerobic digestion. The method comprises the following steps: (1) adding Fe 3+ The method comprises the following steps: (1) adding the polyphenol iron complex to organic solid waste having a solid content of less than 10%; (2) adding the polyphenol iron complex to organic solid waste having a solid content of less than 10%; (3) placing anaerobic sludge in an anaerobic reactor; and (4) continuously injecting the mixture of the polyphenol iron complex and the organic solid waste into the anaerobic reactor, mixing the mixture with the anaerobic sludge, and discharging the mixture after a certain reaction time. The method comprises the following steps: adding the polyphenol iron complex to the organic solid waste anaerobic digestion reactor, and enhancing the anaerobic digestion efficiency of organic matter by enriching dissimilatory iron-reducing bacteria and promoting the electron transfer process in the system.

Description

Technical Field

[0001] The invention belongs to the technical field of anaerobic digestion, and particularly relates to a method for strengthening anaerobic digestion of organic solid waste by utilizing a polyphenol iron complex. Background Art

[0002] Microbial dissimilatory iron reduction is a type of iron-reducing bacteria (e.g. Geobacter 、 Shewanedlla Dissimilatory iron reduction is a process in which iron-rich iron (Fe) directly oxidizes organic matter and transfers the generated electrons to iron oxides via extracellular electron transport proteins or electron shuttles, leading to their reduction. Dissimilatory iron reduction not only bypasses the traditional hydrolysis and acidification process to oxidize complex organic matter but also forms a syntrophic metabolism with methanogens, resulting in higher organic matter oxidation and electron transfer efficiencies. However, the low abundance of dissimilatory iron-reducing bacteria in conventional anaerobic reactors limits the efficiency of dissimilatory iron reduction and syntrophic metabolism.

[0003] Studies have found that adding a small amount of iron oxides to an anaerobic system can effectively increase the abundance of dissimilatory iron-reducing bacteria by stimulating dissimilatory iron reduction. However, the following scientific problems still exist: (1) The efficiency of dissimilatory iron reduction often depends on the physical and chemical characteristics of the iron oxide itself, such as redox potential. Compared with iron oxides with lower reduction potential, iron oxides with high reduction potential are thermodynamically easier to dissimilatory iron reduction. (2) In addition to redox potential, the surface chemical properties of iron oxides and dissimilatory iron-reducing bacteria also affect the rate of dissimilatory iron reduction and the efficiency of enriching dissimilatory iron-reducing bacteria. For example, Fe 3+ When the oxide gains electrons, the Fe 2+ Will be adsorbed on Fe 3+ oxides or dissimilatory iron-reducing bacteria, blocking the surface active sites and thus kinetically limiting the Fe 3+ Therefore, finding an iron oxide that is thermodynamically easy to undergo dissimilatory iron reduction and kinetically reduces the adsorption of Fe(II) is crucial for increasing the abundance of dissimilatory iron-reducing bacteria in anaerobic systems. Summary of the Invention

[0004] In view of the existing technical problems, the present invention provides a method for strengthening the anaerobic digestion of organic solid waste by using polyphenol iron complex. 3+ Fe generated as a reactant 3+ / Fe 2+ —Polyphenolic complexes (hereinafter referred to as polyphenol iron complexes) are amorphous iron oxides with high redox potential and can easily obtain electrons under anaerobic conditions. Polyphenol iron contains a large number of hydroxyl groups and has the ability to chelate Fe. 2+ ions, to prevent them from being adsorbed on Fe 3+Iron polyphenols can effectively enrich iron-reducing bacteria by stimulating iron reduction, thereby blocking surface active sites. Furthermore, the quinone functional groups contained in iron polyphenols have the ability to enhance the efficiency of electron transfer between microorganisms in anaerobic systems. Therefore, iron polyphenols can effectively enrich iron-reducing bacteria by stimulating iron reduction, thereby enhancing the anaerobic digestion process. This method is simple to operate and cost-effective.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A method for enhancing anaerobic digestion of organic solid waste using a polyphenol iron complex comprises the following steps:

[0007] (1) Add Fe to the polyphenol solution 3+ The solution was reacted under nitrogen atmosphere for 24 h to synthesize polyphenol iron complex;

[0008] (2) adding organic solid waste with a solid content of less than 10% into a mixing tank, then adding a certain amount of polyphenol iron complex thereto, stirring evenly, so that the polyphenol iron complex is evenly dispersed in the organic solid waste;

[0009] (3) Take a certain amount of anaerobic sludge and place it in the anaerobic reactor. The initial dosage of anaerobic sludge is 2 / 3 of the volume of the anaerobic reactor;

[0010] (4) Start the delivery pump and continuously inject the mixture of polyphenol iron compound and organic solid waste from the mixing tank into the anaerobic reactor through the bottom feed port of the anaerobic reactor in a continuous flow manner; after the mixture of polyphenol iron compound and organic solid waste enters the anaerobic reactor, it is stirred and evenly mixed with the anaerobic sludge in the anaerobic reactor, and after a certain period of reaction, it is discharged from the top discharge port of the anaerobic reactor.

[0011] Preferably, the polyphenol solution in (1) is obtained by boiling 200 g of green tea in 1 L of water for 30 minutes, cooling and filtering.

[0012] Preferably, the Fe added to 1L of polyphenol solution in (1) 3+ The amount is 0.05-0.2 mol.

[0013] Preferably, Fe in (1) 3+ The solution is FeCl3 solution or Fe(NO3)3 solution, and its concentration can be adjusted according to actual needs.

[0014] Preferably, the dosage of the polyphenol iron complex in (2) is 2 g / L of organic solid waste.

[0015] Preferably, the organic solid waste in (2) is urban surplus sludge and restaurant kitchen waste. Urban surplus sludge refers to the activated sludge discharged from the secondary sedimentation tank during the process of treating domestic sewage in urban sewage treatment plants. Restaurant kitchen waste refers to food processing scraps and food residues generated in kitchens, canteens, etc.

[0016] Preferably, the solid content of the organic solid waste in (2) is 5%-7%.

[0017] Preferably, the anaerobic sludge in (3) is taken from an anaerobic digestion reactor.

[0018] Preferably, the anaerobic reactor in (3) is an upflow anaerobic reactor, the anaerobic reactor is provided with a water bath insulation layer outside, the water temperature is 35-37°C, and a biogas collection device is provided on the top of the anaerobic reactor.

[0019] Preferably, the reaction time in (3) is 15 to 25 days.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This method uses polyphenols to synthesize polyphenol-iron complexes, which contain Fe 3+ 、Fe 2+ The polyphenol iron oxides have high redox potentials and organic functional groups, and the organic functional groups have the ability to transfer electrons. Therefore, when polyphenol iron oxides are added to the anaerobic reactor, they can stimulate the reduction of dissimilatory iron and enrich dissimilatory iron-reducing bacteria, improve the community structure, and strengthen the mutualistic metabolism between dissimilatory iron-reducing bacteria and methanogens, thereby greatly improving the anaerobic digestion efficiency of organic matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart of the present invention using a polyphenol iron complex to enhance anaerobic digestion of organic solid waste;

[0023] In the figure: 1-mixing tank, 2-first agitator, 3-pipeline, 4-delivery pump, 5-feed port, 6-anaerobic reactor, 7-second agitator, 8-gas collecting port, 9-discharge port. Implementation Method

[0024] The technical solutions and effects of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0025] A method for enhancing anaerobic digestion of organic solid waste using polyphenol iron complexes, such as Figure 1 The flowchart shown includes the following steps:

[0026] (1) Boil 200g of green tea in 1L of water for 30 minutes, cool and filter to obtain a polyphenol solution. Add 0.05-0.2mol of Fe 3+ The solution may be a FeCl3 solution or a Fe(NO3)3 solution; reacting for 24 hours under a nitrogen atmosphere to synthesize a polyphenol iron complex;

[0027] (2) Adding organic solid waste with a solid content of less than 10% into a mixing tank 1, then adding a certain amount of polyphenol iron complex thereto, and stirring evenly using a first stirrer 2 to uniformly disperse the polyphenol iron complex in the organic solid waste; in the present invention, 2 g of polyphenol iron complex is added to 1 L of organic solid waste, and the amount can also be 1 g, 3 g, 4 g, or 5 g;

[0028] (3) A certain amount of anaerobic sludge is placed in the anaerobic reactor 6, and the initial amount of anaerobic sludge is 2 / 3 of the volume of the anaerobic reactor 6; the anaerobic sludge of the present invention is taken from the residual sludge anaerobic digestion reactor of the Matougang Sludge Treatment Plant, which has a stable organic matter removal rate and biogas production;

[0029] (4) Start the delivery pump 4 and continuously inject the mixture of the polyphenol iron compound and the organic solid waste from the mixing tank 1 into the anaerobic reactor 6 through the pipe 3 and the bottom feed port 5 of the anaerobic reactor 6 in a continuous flow manner; after the mixture of the polyphenol iron compound and the organic solid waste enters the anaerobic reactor 6, it is stirred by the second agitator 7 and evenly mixed with the anaerobic sludge in the anaerobic reactor 6. After 15 to 25 days, it is discharged from the top discharge port 9 of the anaerobic reactor 6, and the generated biogas enters the biogas collection device through the gas collecting port 8.

[0030] The above method utilizes polyphenol to synthesize polyphenol iron complex, which contains Fe 3+ 、Fe 2+ The polyphenol iron oxides have high redox potentials and organic functional groups, such as quinone / hydroquinone, which have the ability to transfer electrons. Therefore, when polyphenol iron oxides are added to an anaerobic reactor, they can stimulate the reduction of dissimilatory iron and enrich dissimilatory iron-reducing bacteria, improve the community structure, and strengthen the mutualistic metabolism between dissimilatory iron-reducing bacteria and methanogens, thereby greatly improving the anaerobic digestion efficiency of organic matter. Example

[0031] A method for enhancing anaerobic digestion of organic solid waste using a polyphenol iron complex comprises the following steps:

[0032] (1) 200 g of green tea was boiled in 1 L of water for 30 minutes, cooled and filtered to obtain a polyphenol solution. 0.1 mol of Fe(NO3)3 solution was added to the polyphenol solution and reacted under a nitrogen atmosphere for 24 hours to synthesize a polyphenol-iron complex.

[0033] (2) 20 L of municipal waste sludge with a solid content of 6% was added to a mixing tank, and then 40 g of polyphenol iron complex was added thereto and stirred evenly to make the polyphenol iron complex evenly dispersed in the organic solid waste;

[0034] (3) Take a certain amount of anaerobic sludge from a well-functioning anaerobic digestion reactor of urban surplus sludge and place it in the anaerobic reactor. The initial dosage of anaerobic sludge is 2 / 3 of the volume of the anaerobic reactor.

[0035] (4) Start the delivery pump and continuously inject the mixture of polyphenol iron compound and organic solid waste from the mixing tank into the anaerobic reactor through the bottom feed port of the anaerobic reactor in a continuous flow manner; after the mixture of polyphenol iron compound and organic solid waste enters the anaerobic reactor, it is stirred and evenly mixed with the anaerobic sludge in the anaerobic reactor, and is discharged from the top discharge port of the anaerobic reactor after 20 days.

[0036] (5) After treatment, the total chemical oxygen demand removal efficiency of the residual sludge was 54%, and the methane production reached 390 ml / g VS. Example

[0037] A method for enhancing anaerobic digestion of organic solid waste using a polyphenol iron complex comprises the following steps:

[0038] (1) 200 g of green tea was boiled in 1 L of water for 30 minutes, cooled and filtered to obtain a polyphenol solution. 0.1 mol of Fe(NO3)3 solution was added to the polyphenol solution and reacted under a nitrogen atmosphere for 24 hours to synthesize a polyphenol-iron complex.

[0039] (2) Add 10 L of food waste with a solid content of 5% into a mixing tank, then add 20 g of polyphenol iron complex and stir evenly to make the polyphenol iron complex evenly dispersed in the organic solid waste;

[0040] (3) Take a certain amount of anaerobic sludge from a well-functioning anaerobic digestion reactor of urban surplus sludge and place it in the anaerobic reactor. The initial dosage of anaerobic sludge is 2 / 3 of the volume of the anaerobic reactor.

[0041] (4) Start the delivery pump and continuously inject the mixture of polyphenol iron compound and organic solid waste from the mixing tank into the anaerobic reactor through the bottom feed port of the anaerobic reactor in a continuous flow manner; after the mixture of polyphenol iron compound and organic solid waste enters the anaerobic reactor, it is stirred and evenly mixed with the anaerobic sludge in the anaerobic reactor, and is discharged from the top discharge port of the anaerobic reactor after 15 days.

[0042] (5) After the treatment, the total chemical oxygen demand removal efficiency of the food waste was 72%, and the methane production reached 520ml / g VS.

[0043] Comparative Example 1

[0044] The difference between this comparative example and Example 1 is that the polyphenol iron compound is replaced with ferrosoferric oxide powder, specifically:

[0045] (1) 20 L of municipal waste sludge with a solid content of 6% was added to a mixing tank, followed by the addition of 40 g of ferroferric oxide powder and stirring to uniformly disperse the polyphenol iron complex in the organic solid waste.

[0046] (2) Take a certain amount of anaerobic sludge from a well-functioning anaerobic digestion reactor of urban surplus sludge and place it in the anaerobic reactor. The initial dosage of anaerobic sludge is 2 / 3 of the volume of the anaerobic reactor.

[0047] (3) Start the delivery pump and continuously inject the mixture of ferroferric oxide powder and organic solid waste from the mixing tank into the anaerobic reactor through the bottom feed port of the anaerobic reactor in a continuous flow manner; after the mixture of polyphenol iron complex and organic solid waste enters the anaerobic reactor, it is stirred and evenly mixed with the anaerobic sludge in the anaerobic reactor, and is discharged from the top discharge port of the anaerobic reactor after 20 days.

[0048] (5) After treatment, the total chemical oxygen demand removal efficiency of the residual sludge was 48%, and the methane production reached 365 ml / g VS. Compared with Case 1, the total chemical oxygen demand removal efficiency decreased by 6%, and the methane production decreased by 25 ml / g VS.

[0049] Comparative Example 2

[0050] The difference between this comparative example and Example 1 is that no iron oxide is added, specifically:

[0051] (1) Add 20 L of municipal waste sludge with a solid content of 6% into the mixing tank;

[0052] (2) Take a certain amount of anaerobic sludge from a well-functioning anaerobic digestion reactor of urban surplus sludge and place it in the anaerobic reactor. The initial dosage of anaerobic sludge is 2 / 3 of the volume of the anaerobic reactor.

[0053] (3) Start the delivery pump and continuously inject the mixture of organic solid waste from the mixing tank into the anaerobic reactor through the bottom feed port of the anaerobic reactor in a continuous flow manner; after the mixture of organic solid waste enters the anaerobic reactor, it is stirred and evenly mixed with the anaerobic sludge in the anaerobic reactor, and is discharged from the top discharge port of the anaerobic reactor after 20 days.

[0054] (4) After treatment, the total chemical oxygen demand removal efficiency of the residual sludge was 39%, and the methane production reached 310 ml / g VS. Compared with Case 1, the total chemical oxygen demand removal efficiency was 15% lower, and the methane production was 80 ml / g VS lower. Compared with Comparative Example 1, the total chemical oxygen demand removal efficiency was reduced by 9%, and the methane production was reduced by 55 ml / g VS.

[0055] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for enhancing anaerobic digestion of organic solid waste using a polyphenol iron complex, characterized in that: The method comprises the following steps: (1) Add Fe to the polyphenol solution 3+ The solution was reacted under nitrogen atmosphere for 24 h to synthesize polyphenol iron complex; The polyphenol solution in (1) is obtained by boiling 200 g of green tea in 1 L of water for 30 minutes, cooling and filtering; Fe added to 1L polyphenol solution in (1) 3+ The amount is 0.05-0.2 mol; (2) adding organic solid waste with a solid content of less than 10% into a mixing tank, then adding a certain amount of polyphenol iron complex thereto, stirring evenly, so that the polyphenol iron complex is evenly dispersed in the organic solid waste; The dosage of the polyphenol iron complex in (2) is 2 g / L organic solid waste; (3) Take a certain amount of anaerobic sludge and place it in the anaerobic reactor. The initial dosage of anaerobic sludge is 2 / 3 of the volume of the anaerobic reactor; (4) starting the delivery pump to continuously inject the mixture of the polyphenol iron compound and the organic solid waste from the mixing tank into the anaerobic reactor through the bottom feed port of the anaerobic reactor in a continuous flow manner; after the mixture of the polyphenol iron compound and the organic solid waste enters the anaerobic reactor, it is stirred and evenly mixed with the anaerobic sludge in the anaerobic reactor, and after a certain period of reaction, it is discharged from the top discharge port of the anaerobic reactor; The complex is Fe 3+ / Fe 2+ —Polyphenolic compounds, belonging to amorphous iron oxides, containing Fe 3+ 、Fe 2+ and organic functional group quinone; high redox potential, easy to obtain electrons under anaerobic conditions; The complex itself contains a large number of hydroxyl groups and has the function of chelating Fe 2+ ions to prevent them from being adsorbed on Fe 3+ The quinone functional groups contained in it have the ability to enhance the efficiency of electron transfer between microorganisms in anaerobic systems.

2. The method for enhancing anaerobic digestion of organic solid waste using a polyphenol iron complex according to claim 1, wherein: Fe in (1) 3+ The solution is FeCl3 solution or Fe(NO3)3 solution.

3. The method for enhancing anaerobic digestion of organic solid waste using a polyphenol iron complex according to claim 1, wherein: The organic solid waste in (2) is urban residual sludge and restaurant kitchen waste.

4. The method for enhancing anaerobic digestion of organic solid waste using a polyphenol iron complex according to claim 1, wherein: The solid content of the organic solid waste in (2) is 5%-7%.

5. The method for enhancing anaerobic digestion of organic solid waste using a polyphenol iron complex according to claim 1, wherein: The anaerobic sludge in (3) is taken from the anaerobic sludge digestion reactor.

6. The method for enhancing anaerobic digestion of organic solid waste using a polyphenol iron complex according to claim 1, wherein: The anaerobic reactor in (3) is an upflow anaerobic reactor, and a water bath insulation layer is provided outside the anaerobic reactor, and the water temperature is 35-37°C. A biogas collection device is provided on the top of the anaerobic reactor.

7. The method for enhancing anaerobic digestion of organic solid waste using a polyphenol iron complex according to claim 1, wherein: The reaction time in (3) is 15 to 25 days.

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