Method for enhancing anaerobic fermentation of kitchen waste to produce acetic acid

Abstract

The invention provides a method for enhancing anaerobic fermentation of kitchen waste to produce acetic acid, and belongs to the technical field of environmental protection and recycling. According to the method, the kitchen waste is used as a substrate, mixed fermentation microorganisms and a magnetic graphene oxide nano material are added into an anaerobic reactor, certain temperature and pH are controlled, anaerobic fermentation reaction is performed, and the yield of acetic acid in the anaerobic fermentation acid production process of the kitchen waste is remarkably increased. The process of producing acetic acid through anaerobic fermentation is simple to operate, secondary pollution is not generated, the kitchen waste is converted into acetic acid with high economic value, waste is turned into wealth, and resourceful treatment of the kitchen waste is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection and resource utilization, and in particular to a method for enhancing acetic acid production by fermentation of kitchen waste. Background Art

[0002] With the improvement of living standards and the development of the catering industry, the proportion of restaurant waste in my country's urban waste has increased significantly. How to effectively deal with restaurant waste has become a major problem facing people. Restaurant waste is rich in easily degradable organic components and trace elements such as nitrogen, phosphorus, and potassium, and has both environmental damage and resource recovery properties. Anaerobic fermentation of restaurant waste to produce volatile fatty acids (VFAs) can not only avoid environmental pollution caused by restaurant waste, but also effectively recycle resources. It has become an important way to treat restaurant waste.

[0003] In recent years, in the research and practice of using food waste to ferment VFAs, the directional bioconversion of food waste into VFAs such as acetic acid, propionic acid, and butyric acid has gradually become a hot topic. However, in the process of directional anaerobic fermentation of food waste to produce acetic acid, the presence of mixed microorganisms leads to a relatively low efficiency of acetic acid production. In addition, the complex characteristics of high oil and high salt in food waste also directly or indirectly affect the growth and metabolic activities of anaerobic fermentation microorganisms, thereby affecting the stability of the entire anaerobic fermentation system. Therefore, it is urgent to find methods to improve the efficiency and stability of anaerobic fermentation of acetic acid by mixed microorganisms, so as to achieve efficient directional bioconversion of food waste. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention provides a method for strengthening the production of acetic acid by fermentation of kitchen waste. The present invention uses magnetic graphene oxide nanomaterials to strengthen the metabolic process of anaerobic fermentation of kitchen waste to produce acetic acid, providing a new technology for the resource-oriented biological conversion of kitchen waste.

[0005] The technical solution of the present invention is as follows:

[0006] A method for enhancing anaerobic fermentation of kitchen waste to produce acetic acid is characterized in that mixed fermentation bacteria and magnetic graphene oxide nanomaterials are added to an anaerobic fermentation reactor of the kitchen waste, and a certain temperature and pH are controlled to carry out anaerobic fermentation and acid production reaction.

[0007] Furthermore, the dosage of the magnetic graphene oxide nanomaterial is 0.001-0.01 g / g TS, and more preferably 0.004-0.008 g / g TS.

[0008] Furthermore, the Fe 3 O 4The particle size of the nanoparticles is 30 to 100 nm, more preferably 30 to 50 nm.

[0009] Furthermore, the anaerobic fermentation acid production temperature is 10-55°C, and more preferably 20-35°C.

[0010] Furthermore, the pH of the anaerobic fermentation substrate is 6-9, and more preferably 7-8.

[0011] Furthermore, the anaerobic fermentation acid production time is 3 to 7 days, and more preferably 4 to 6 days.

[0012] The basic principle of the present invention using magnetic graphene oxide material to strengthen the anaerobic fermentation of kitchen waste to produce acetic acid is as follows:

[0013] (1) Magnetic graphene oxide nanomaterials can penetrate into fermentation microbial cells and directly or indirectly promote NADH oxidation as an electron acceptor, converting it into NAD+, accelerating the electron transfer process, and maintaining NADH / NAD + Balance, promoting the metabolic pathway to acetate production.

[0014] (2) Under anaerobic conditions, ferric iron oxides can trigger the dissimilatory iron reduction process and accelerate the interspecies hydrogen transfer of anaerobic hydrolysis and acidification of organic matter in food waste. 3 O 4 It can effectively enrich dissimilatory iron-reducing bacteria, so that the hydrolysis acidification reactor can still maintain stable operation under acid shock and high organic load conditions. As the reaction time increases, dissimilatory iron-reducing bacteria are effectively enriched, which can use the H generated by the oxidation of organic matter to 2 Acts as an electron donor, reduces hydrogen content, and promotes acetic acid fermentation.

[0015] (3) Magnetic graphene oxide nanomaterials produce iron ions in the anaerobic fermentation system, which increases the activity of key enzymes in the VFAs production process, especially the key enzymes in the pyruvate-acetate production pathway, such as acetate kinase (ACK) and phosphotransacetylase (PTA), thereby increasing the production of acetate in anaerobic fermentation.

[0016] (4) Methanogens are relatively sensitive. The graphene oxide sheet structure can easily destroy the cell membrane of methanogens, blocking the material exchange and metabolic pathways between the cell and the surrounding environment, inhibiting cell life activities, and even causing cell rupture and death. Acetogenic methanogens are a type of heterotrophic archaea that mainly use acetate as nutrition. Their rupture and death can reduce the consumption of acetate and further achieve the accumulation of acetate in VFAs produced by anaerobic fermentation.

[0017] The beneficial technical effects of the present invention are:

[0018] (1) Compared with conventional anaerobic fermentation of food waste, this method can significantly increase the accumulation of acetic acid in VFAs and has the advantages of simple operation and significant increase in acetic acid production.

[0019] (2) Acetic acid is an important chemical raw material with a wide range of applications. However, most industrial acetic acid is currently produced by carbonylation of methanol, which often contains heavy metals, benzene and other impurities, and the synthesis process will cause a burden on the environment. Therefore, the development and utilization of functional materials to improve the technology of anaerobic fermentation of food waste to produce acetic acid has great economic value.

[0020] (3) The concept of improving the efficient conversion of food waste into acetic acid can be extended to the actual treatment of organic wastewater, effectively converting organic wastewater and other industrial wastewater into acetic acid with higher utilization value, reducing the pollution and destructive effects of organic pollutants in wastewater on the environment, which is in line with the concept of circular economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 This is a morphology diagram of magnetic graphene oxide prepared by the present invention; DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The food waste used in the following examples was taken from the canteen, and was manually selected to remove larger foreign matter (such as bones and plastic bags). The large pieces of food waste were then crushed into small pieces by a crusher, and tap water was added to dilute it 3 times to obtain a food waste fermentation substrate (VSS = 10 g / L). The main organic components in the food waste substrate include about 30% protein, 57% carbohydrates, and 13% lipid substances. The fermentation mixed bacteria used in the examples were taken from a food waste fermentation acid production reactor that has been in long-term stable operation.

[0025] Embodiment 1 (blank example):

[0026] In a 250 mL organic glass anaerobic fermentation reactor, 180 mL of food waste and fermentation mixed bacteria were added as the substrate and bacteria for anaerobic fermentation. The pH value in the reactor was adjusted to 8.0 with 6 M NaOH and 6 M HCl, and then N 2 Purge for 2 minutes to create anaerobic conditions. The anaerobic fermentation temperature was controlled at 35°C and the anaerobic fermentation time was 6 days. No external materials were added, and the food waste was converted into acetic acid only through the action of the mixed microorganisms themselves. Under the above operating conditions, the VFAs production in the food waste anaerobic fermentation reactor reached 7652 mgCOD / L, the acetic acid production was 2450 mg / L, and the acetic acid ratio was 34.3%.

[0027] Embodiment 2:

[0028] In a 250 mL organic glass anaerobic fermentation reactor, 180 mL of food waste and fermentation mixed bacteria were added as the substrate and strain for anaerobic fermentation. 0.008 g / g TS of magnetic graphene oxide nanomaterials was added simultaneously. The pH value in the reactor was adjusted to 8.0 with 6 M NaOH and 6 M HCl, and then N 2 The anaerobic conditions were created by blowing for 2 minutes. The anaerobic fermentation temperature was controlled at 35°C and the anaerobic fermentation time was 6 days. The food waste was converted into acetic acid through the action of mixed microorganisms. Under the above operating conditions, the VFAs production in the food waste anaerobic fermentation reactor reached 12358 mgCOD / L, the acetic acid production was 6755 mg / L, and the acetic acid ratio was 56.9%.

[0029] Embodiment 3:

[0030] In a 250 mL organic glass anaerobic fermentation reactor, 180 mL of food waste and fermentation mixed bacteria were added as the substrate and strain for anaerobic fermentation. 0.01 g / g TS of magnetic graphene oxide nanomaterials was added simultaneously. The pH value in the reactor was adjusted to 8.0 with 6 M NaOH and 6 M HCl, and then N 2 The anaerobic conditions were created by blowing for 2 minutes. The anaerobic fermentation temperature was controlled at 35°C and the anaerobic fermentation time was 6 days. The food waste was converted into acetic acid through the action of mixed microorganisms. Under the above operating conditions, the VFAs production in the food waste anaerobic fermentation reactor reached 12955 mgCOD / L, the acetic acid production was 6980 mg / L, and the acetic acid ratio was 57.7%.

[0031] Embodiment 4:

[0032] In a 250 mL organic glass anaerobic fermentation reactor, 180 mL of food waste and fermentation mixed bacteria were added as the substrate and strain for anaerobic fermentation. 0.01 g / g TS of magnetic graphene oxide nanomaterials was added simultaneously. The pH value in the reactor was adjusted to 9.0 with 6 M NaOH and 6 M HCl, and then N 2 The anaerobic conditions were created by blowing for 2 minutes. The anaerobic fermentation temperature was controlled at 35°C and the anaerobic fermentation time was 6 days. The food waste was converted into acetic acid through the action of mixed microorganisms. Under the above operating conditions, the VFAs production in the food waste anaerobic fermentation reactor reached 11045 mgCOD / L, the acetic acid production was 6210 mg / L, and the acetic acid ratio was 60.1%.

[0033] Embodiment 5:

[0034] In a 250 mL organic glass anaerobic fermentation reactor, 180 mL of food waste and fermentation mixed bacteria were added as the substrate and strain for anaerobic fermentation. 0.01 g / g TS of magnetic graphene oxide nanomaterials was added simultaneously. The pH value in the reactor was adjusted to 9.0 with 6 M NaOH and 6 M HCl, and then N 2 The anaerobic conditions were created by blowing for 2 minutes. The anaerobic fermentation temperature was controlled at 20°C and the anaerobic fermentation time was 6 days. The food waste was converted into acetic acid through the action of mixed microorganisms. Under the above operating conditions, the VFAs production in the food waste anaerobic fermentation reactor reached 9845 mgCOD / L, the acetic acid production was 5315 mg / L, and the acetic acid ratio was 57.8%.

[0035] Embodiment 6:

[0036] In a 250 mL organic glass anaerobic fermentation reactor, 180 mL of food waste and fermentation mixed bacteria were added as the substrate and strain for anaerobic fermentation. 0.008 g / g TS of magnetic graphene oxide nanomaterials was added simultaneously. The pH value in the reactor was adjusted to 8.0 with 6 M NaOH and 6 M HCl, and then N 2 The anaerobic conditions were created by blowing for 2 minutes. The anaerobic fermentation temperature was controlled at 35°C and the anaerobic fermentation time was 7 days. The food waste was converted into acetic acid through the action of mixed microorganisms. Under the above operating conditions, the VFAs production in the food waste anaerobic fermentation reactor reached 12466 mgCOD / L, the acetic acid production was 6912 mg / L, and the acetic acid ratio was 59.3%.

[0037] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and implementation modes, and can be fully applicable to various fields suitable for the present invention. For those familiar with the art, for those of ordinary skill in the art, various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for enhancing anaerobic fermentation of kitchen waste to produce acetic acid, characterized in that: Mixed fermentation bacteria and magnetic graphene oxide nanomaterials are added to the anaerobic fermentation reactor of food waste, and the temperature and pH are controlled to carry out anaerobic fermentation and acid production reaction.

2. The method according to claim 1, characterized in that: The dosage of the magnetic graphene oxide nanomaterial is 0.001-0.01 g / g TS; the TTS is the dry weight of kitchen waste.

3. The method according to claim 2, characterized in that The particle size of the Fe3O4 nanoparticles in the magnetic graphene oxide nanomaterial is 30-100 nm.

4. The method according to claim 1, characterized in that: The anaerobic fermentation temperature is 20-55°C.

5. The method according to claim 1, characterized in that The pH of the anaerobic fermentation substrate is 6-9.

6. The method according to claim 1, characterized in that The anaerobic fermentation time is 3 to 7 days.

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