CN105755059B - A method for increasing the synthesis concentration of carbon chain biological extension products - Google Patents

Abstract

The invention relates to a method for improving the synthetic concentration of a carbon chain biological extension product, which converts low-carbon chain organic acid into medium-long carbon chain organic acid and comprises the following steps: filling an anaerobic reactor with an electric conductive carbon-based material; introducing anaerobic sludge generated by sewage treatment, biogas residues generated by anaerobic digestion of garbage, water body bottom mud, petroleum-polluted soil or brewing residues into an anaerobic reactor as a starter microbial agent for carbon chain biological extension; and continuously introducing a low-carbon chain organic acid raw material and an electron donor reactant into the anaerobic reactor, converting the low-carbon chain organic acid into medium-long carbon chain organic acid under the action of a microbial inoculum, and continuously discharging. Compared with the prior art, the conductive carbon-based material capable of promoting the enrichment of the carbon chain organism extension microorganisms is introduced into the anaerobic reaction system, so that the capability of the carbon chain extension microorganisms for resisting short carbon chain and medium and long carbon chain organic acids can be improved, and the synthetic concentration of the medium and long carbon chain organic acids is further improved.

Description

A method for increasing the synthesis concentration of carbon chain biological extension products

technical field

The invention belongs to the field of environmental protection and comprehensive utilization of resources, and in particular relates to a method for increasing the synthesis concentration of carbon chain biological extension products.

Background technique

The terminal fermentation products of natural fermentation of biomass waste are mainly low-chain organic acids. Due to the high mixing degree of biomass waste itself and the mixed growth of microorganisms, the concentration of low-carbon chain organic acids is low, the amount of impurities introduced by the waste source is high, and the non-target intermediate metabolites are mixed; The high hydrophilicity leads to poor separability, high cost of separation by filtration, evaporation or distillation, which is not conducive to the conversion to ethanol and butanol by high temperature or catalytic hydrogenation (energy densities of 20.9 and 29.2 MJ/L, respectively). Therefore, these liquid fermentation products can only be used in occasions where the purity of the feed is not high, such as as a carbon source for nitrogen and phosphorus removal in wastewater treatment [Lee WS, Chua ASM, Yeoh HK, Ngoh GC. 2014. Review of the production and applications of waste-derived volatile fatty acids. Chemical Engineering Journal 235:83-99.].

In order to solve the above problems, the carbon chain of organic matter can be extended through repolymerization technology, and the resource grade of waste fermentation products can be further improved at a reasonable cost. That is, the low-carbon chain organic acid is converted into a medium and long carbon chain organic acid with a higher number of carbon atoms, and it becomes the precursor raw material of mixed alcohol, alkane, ester and other fuels or solvents. Compared with chemical extension technology, carbon chain biological extension technology using mixed bacteria has the advantages of low cost, mild reaction conditions and no chemical addition [AglerMT,Wrenn BA,Zinder SH,Angenent LT.2011.Waste to bioproduct conversion with undefined mixed cultures: The carboxylate platform. Trends in Biotechnology 29:70-78.].

However, the concentration of medium and long carbon chain products synthesized by carbon chain biological extension technology is currently low. According to the calculation, if the organic acid concentration is above 30g/L, the separation cost can be greatly reduced. However, the highest concentration of caproate synthesis in the known mixed bacterial carbon chain biological extension system is only 8.27-12.8g/L [Steinbusch KJJ, Hamelers HVM, Plugge CM, Buisman CJN.2011. Biological formation of caproate and caprylate from acetate :Fuel and chemical production from low grade biomass.Energy&EnvironmentalScience 4:216-224.]【Weimer PJ,Stevenson DM.2011.Isolation,characterization,and quantification of Clostridium kluyveri from the bovine rumen.AppliedMicrobiology and Biotechnology 94:461-466. ]. This is because molecular carbon chain extension products (medium and long carbon chain organic acids) can cause severe product inhibition to microorganisms [Vasudevan D, Richter H, AngenentLT. 2014. Upgrading dilute ethanol from syngas fermentation to n-caproate withreactor microbiomes. Bioresource Technology 151:378-382.]. Furthermore, high product output means that high concentrations of low chain organic acid substrates need to be input, which can also lead to substrate inhibition. Therefore, it is necessary to develop a technical method that can improve the ability of mixed flora to resist organic acid inhibition, thereby increasing the synthesis concentration of carbon chain biological extension products.

The Chinese invention patent "Method and Device for Electro-promoting Carbon Chain Biological Extension" (application number CN201510019239.8) adopts the method of applied electric current to promote the carbon chain biological extension reaction.

The scientific article【Application of eco-compatible biochar in anaerobic digestion to relieve acid stress and promote the selective colonization of functionalmicrobes.Water Research 68:710-718.】applied biochar to the anaerobic digestion of glucose to produce methane, and found that biochar can The fermentation of glucose to produce short-chain organic acids (acetic acid, butyric acid, and propionic acid) is promoted, and the rate of degradation of short-chain organic acids into methane is also accelerated.

Scientific article [Andersen, S.J., Candry, P., Basadre, T., Khor, W.C., Roume, H., Hernandez-Sanabria, E., Coma, M. and Rabaey, K. (2015) Electrolytic extractiondrives volatile fatty acid chain elongation through lactic acid and replaceschemical pH control in thin stillage fermentation. Biotechnology for Biofuels 8(1), 1-14.] The resulting carbon chain extension products are separated in real time by means of membrane electrolytic extraction to reduce their concentration in the reactor , to avoid organic acid inhibition.

Science and technology article【Agler,M.T.,Spirito,C.M.,Usack,J.G.,Werner,J.J.and Angenent,L.T.(2012)Chain elongation with reactor microbiomes:Upgrading dilute ethanolto medium-chain carboxylates.Energy&Environmental Science 5(8),8189-8192. ] The carbon chain extension product is separated by driving liquid-liquid extraction through pH gradient, so as to reduce its concentration in the reactor and avoid organic acid inhibition.

SUMMARY OF THE INVENTION

Based on the above technical background, the present invention proposes a method for increasing the synthesis concentration of carbon chain biological extension products. The key to this method is to introduce an auxiliary substrate that can promote electron transfer in the reaction system, thereby helping to improve the ability of microorganisms to resist inhibition, that is, to improve the reactivity of microorganisms.

The object of the present invention can be realized through the following technical solutions:

A method for improving the synthesis concentration of carbon chain biological extension products, converting low carbon chain organic acids into medium and long carbon chain organic acids, the method comprising the following steps:

(1) Fill the anaerobic reactor with conductive carbon-based material;

(2) Introduce into the anaerobic reactor anaerobic sludge produced by sewage treatment, biogas residue produced by anaerobic digestion of garbage, water body bottom sludge, oil-contaminated soil or brewing residue as the starting inoculant for carbon chain biological extension;

(3) The low-carbon chain organic acid raw material and the electron donor reactant are continuously fed into the above-mentioned anaerobic reactor. Under the action of the bacterial agent, the low-carbon chain organic acid is converted into a medium and long carbon chain organic acid, and the discharge.

Preferably, the conductive carbon-based material includes activated carbon, bio-carbon, graphite, or modified materials that still have conductivity after these carbon-based materials are modified.

Preferably, the particle size of the conductive carbon-based material is less than 100 microns.

Preferably, the volume filling rate of the conductive carbon-based material in the anaerobic reactor is greater than or equal to 5%.

Preferably, the parameters of the anaerobic reactor are: the reaction temperature is 25-60° C., the pH is 6-7, and the hydraulic retention time is greater than or equal to 5 days.

Preferably, the low-carbon chain organic acid raw material is a clear liquid obtained by hydrolysis and acidification of biomass waste and obtained by solid-liquid separation, and the total mass fraction of acetic acid, propionic acid and butyric acid in the liquid is greater than or equal to the total amount of organic matter in the liquid 80%.

Preferably, the biomass waste includes kitchen waste, fruit and vegetable waste, sludge, livestock manure or food processing residue.

Preferably, the electron donor reactant is selected from ethanol, lactic acid or hydrogen.

Preferably, in the feed of the low-chain organic acid raw material and the electron donor reactant, the concentration of the electron donor reactant is greater than or equal to 25 mmol/L.

The present invention adds a conductive carbon-based material as an auxiliary substrate in the carbon chain biological extension reaction, so that the ability of the carbon chain extension microorganism to tolerate short carbon chain and medium and long carbon chain organic acids can be improved, thereby improving the medium and long carbon chain. Synthetic concentrations of organic acids.

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

1. The introduction of conductive carbon-based materials can promote the interspecific electron transfer of microorganisms with carbon chain biological extension function in the inoculum, thereby forming a microbial network aggregation area with a radius of hundreds of microns in the area with carbon-based materials as the core , to achieve high abundance enrichment of carbon chain biological extension microorganisms, and improve the tolerance to inhibition by molecular organic acids.

2. As a result, the synthetic concentration of medium and long carbon chain organic acids in the reactor filled with the conductive carbon-based material can be greatly increased, thereby increasing the product value of the carbon chain biological extension product.

Description of drawings

FIG. 1 is a schematic structural diagram of a carbon chain biological extension reactor in the present invention.

Each label in the figure is as follows: 1-carbon chain biological extension microorganism; 2-low carbon chain organic acid raw material; 3-electron donor reactant; 4-feeding port; 5-anaerobic reactor; 6-lower porous plate; 7-lower geotextile; 8-conductive activated carbon; 9-filling reaction zone; 10-upper geotextile; 11-upper porous plate; 12-upper buffer zone; 13-discharge port; 14-water outlet; 15-side road; 16 - Transfer pump.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1

A method for increasing the synthesis concentration of carbon chain biological extension products: with reference to Figure 1, first, brewing residue is used as a starter inoculant, and the residue is rich in carbon chain biological extension microorganisms such as Clostridium klebsiella 1; The fermentation broth obtained by hydrolysis, acidification and centrifugation was used as a low-carbon organic acid raw material 2. The n-butyric acid content of the fermentation broth accounted for 80% of the total organic matter, and the n-butyric acid concentration was 250 mmol/L; the ethanol aqueous solution was used as the electron donor reactant. 3. The ethanol concentration is 250mmol/L.

The low carbon chain organic acid raw material 2 and the electron donor reactant 3 enter the anaerobic reactor 5 from the feeding port 4, and then enter the conductive activated carbon 8 filled with a particle size of 50 μm after passing through the lower porous plate 6 and the overlying lower geotextile 7 Filling reaction zone 9; carbon chain biological extension microorganisms 1 can be enriched around conductive activated carbon 8 to convert n-butyric acid and ethanol into n-hexanoic acid; the volume filling rate of conductive activated carbon 8 in filling reaction zone 9 is 15%, and the reaction zone The effective volume can ensure that the hydraulic retention time of the reaction solution in this zone is 15 days; the solution rich in n-hexanoic acid enters the upper buffer zone 12 from the upper part of the filled reaction zone 9 through the upper geotextile 10 and the upper perforated plate 11, and passes through the upper buffer zone 12. The discharge port 13 flows out, and the effluent is the effluent 14 .

In the anaerobic reactor 5, a temperature control device is used to maintain the temperature in the reactor at 30°C, and a pH control system is used to maintain the pH in the reactor at 7. In order to promote the flow of the solution in the reactor and further improve the conversion rate, the reactor is provided with a side road 15, and the side road 15 is provided with a delivery pump 16, through which the upper buffer zone 12 and the filling reaction zone 9 are realized. cycle.

The concentration of n-hexanoic acid in the effluent 14 can reach up to 23 g/L (in the alcohol aqueous solution system); the conversion rate of n-butyric acid can reach 90%.

Example 2

Referring to Figure 1, the difference from Embodiment 1 is:

In this embodiment, biochar is used instead of conductive activated carbon as the conductive carbon-based material. The particle size of biochar is 80 microns.

In this embodiment, the anaerobic sludge produced by sewage treatment is introduced into the anaerobic reactor as a start-up bacterial agent for carbon chain biological extension.

In this example, the volume filling rate of the conductive carbon-based material in the anaerobic reactor is 5%.

In this embodiment, the parameters of the anaerobic reactor are: the reaction temperature is 25° C., the pH is 6, and the hydraulic retention time is 5 days.

In this embodiment, the low-carbon chain organic acid raw material is a clear liquid obtained by hydrolysis and acidification of fruit and vegetable waste and obtained by solid-liquid separation, and the total mass fraction of acetic acid, propionic acid and butyric acid in the liquid is equal to the total amount of organic matter in the liquid 80%.

In this embodiment, the electron donor reactant is lactic acid, and in the feed of the low-carbon chain organic acid raw material and the electron donor reactant, the concentration of the electron donor reactant is equal to 25 mmol/L.

In the method of this embodiment, the carbon chain biological extension microorganisms in the inoculant are activated to convert acetic acid, propionic acid and butyric acid into n-hexanoic acid; and the conversion rate of acetic acid, propionic acid and butyric acid is over 90%.

Example 3

Referring to Figure 1, the difference from Embodiment 1 is:

In this embodiment, graphite is used instead of conductive activated carbon as the conductive carbon-based material. The particle size of graphite is less than 100 microns.

In this example, the biogas residue produced by the anaerobic digestion of waste is introduced into the anaerobic reactor as a starter inoculant for biological extension of the carbon chain.

In this embodiment, the volume filling rate of the conductive carbon-based material in the anaerobic reactor is 10%.

In this embodiment, the parameters of the anaerobic reactor are: the reaction temperature is 40° C., the pH is 7, and the hydraulic retention time is 8 days.

In this embodiment, the low-carbon chain organic acid raw material is a clarified liquid obtained by hydrolysis and acidification of sludge and obtained by solid-liquid separation, and the total mass fraction of acetic acid, propionic acid and butyric acid in the liquid is the total amount of organic matter in the liquid 85%.

In this embodiment, the electron donor reactant is hydrogen, and in the feed of the low-carbon chain organic acid raw material and the electron donor reactant, the concentration of the electron donor reactant is 55 mmol/L.

In the method of this embodiment, the carbon chain biological extension microorganisms in the inoculant are activated to convert acetic acid, propionic acid and butyric acid into n-hexanoic acid; and the conversion rate of acetic acid, propionic acid and butyric acid is over 90%.

Example 4

Referring to Figure 1, the difference from Embodiment 1 is:

In this embodiment, the modified bio-carbon which still has conductivity after modification of the bio-char is used as the conductive carbon-based material instead of the conductive activated carbon. The particle size of the modified biochar is 50 microns.

In this embodiment, oil-contaminated soil is introduced into the anaerobic reactor as a starter agent for biological extension of carbon chains.

In this example, the volume filling rate of the conductive carbon-based material in the anaerobic reactor was 25%.

In this embodiment, the parameters of the anaerobic reactor are: the reaction temperature is 60° C., the pH is 6, and the hydraulic retention time is 10 days.

In this embodiment, the low-carbon chain organic acid raw material is a clear liquid obtained by hydrolysis and acidification of livestock and poultry manure and obtained by solid-liquid separation, and the total mass fraction of acetic acid, propionic acid and butyric acid in the liquid is the total organic matter in the liquid. 83% of the amount.

In this embodiment, the electron donor reactant is lactic acid, and in the feed of the low-carbon chain organic acid raw material and the electron donor reactant, the concentration of the electron donor reactant is 125 mmol/L.

In the method of this embodiment, the carbon chain biological extension microorganisms in the inoculant are activated to convert acetic acid, propionic acid and butyric acid into n-hexanoic acid; and the conversion rate of acetic acid, propionic acid and butyric acid is over 90%.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (6)

1. A method for improving the synthetic concentration of carbon chain biological extension products is used for converting low-carbon chain organic acid into medium-long carbon chain organic acid, and is characterized by comprising the following steps:

(1) filling an anaerobic reactor with an electric conductive carbon-based material;

(2) introducing anaerobic sludge generated by sewage treatment, biogas residues generated by anaerobic digestion of garbage, water body bottom mud, petroleum-polluted soil or brewing residues into an anaerobic reactor as a starter microbial agent for carbon chain biological extension;

(3) continuously introducing a low-carbon chain organic acid raw material and an electron donor reactant into the anaerobic reactor, converting the low-carbon chain organic acid into medium-long carbon chain organic acid under the action of a microbial inoculum, and continuously discharging;

the conductive carbon-based material is selected from activated carbon, biochar, modified activated carbon still having conductivity after modification or modified biochar still having conductivity after modification;

the particle size of the conductive carbon-based material is less than 100 microns, and the volume filling rate of the conductive carbon-based material in the anaerobic reactor is more than or equal to 5 percent;

the introduction of the conductive carbon-based material can promote the inter-species electron transfer of microorganisms with the carbon chain biological extension function in the microbial inoculum, so that a microorganism reticular accumulation area with the radius range of hundreds of microns is formed in an area taking the carbon-based material as a core, and the high-abundance enrichment of the carbon chain biological extension microorganisms is realized.

2. The method for increasing the synthesis concentration of carbon chain biological extension products according to claim 1, wherein the parameters of the anaerobic reactor are as follows: the reaction temperature is 25-60 ℃, the pH value is 6-7, and the hydraulic retention time is more than or equal to 5 days.

3. The method of claim 1, wherein the electron donor reactant is selected from the group consisting of ethanol, lactic acid, and hydrogen.

4. The method for increasing the synthesis concentration of carbon chain biological extension products as claimed in claim 1, wherein the concentration of the electron donor reactant in the feed of the low carbon chain organic acid raw material and the electron donor reactant is greater than or equal to 25 mmol/L.

5. The method for improving the synthesis concentration of carbon chain biological extension products according to claim 1, wherein the low-carbon chain organic acid raw material is a clarified liquid obtained by hydrolyzing and acidifying biomass waste and performing solid-liquid separation, and the mass total fraction of acetic acid, propionic acid and butyric acid in the clarified liquid is greater than or equal to 80% of the total organic matter content in the clarified liquid.

6. The method for increasing the synthesis concentration of carbon chain biological extension products according to claim 5, wherein the biomass waste comprises kitchen waste, fruit and vegetable waste, sludge, livestock and poultry manure or food processing residues.

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