阅读说明：本技术 木醋液能源化利用的方法 (Method for recycling wood vinegar ) 是由 李岩 华栋梁 范庆文 许海朋 赵玉晓 陈雷 赵保峰 金付强 于 2019-12-02 设计创作，主要内容包括：一种木醋液能源化利用的方法,它包括如下步骤：(1)木醋液的制备；(2)预分离除油；(3)稀释；(4)三维铁炭电解处理木醋液；(5)厌氧发酵产甲烷包括厌氧颗粒污泥驯化和采用升流式厌氧污泥床作为产甲烷反应装置,将驯化好的厌氧颗粒污泥置于产甲烷反应装置中,加入静置后约占产甲烷反应装置总体积的一半；步骤(3)上层液体部分经电解后调节液体pH至7.0后进入UASB中,在产甲烷反应器中有机物在产酸菌的作用下生成乙酸、氢气和二氧化碳,并继而被产甲烷菌利用转化成甲烷。(A method for recycling pyroligneous liquor comprises the following steps: (1) preparing wood vinegar; (2) pre-separating and removing oil; (3) diluting; (4) electrolyzing wood vinegar with three-dimensional iron carbon; (5) anaerobic fermentation methane production comprises anaerobic granular sludge domestication and an upflow anaerobic sludge bed as a methane production reaction device, wherein the domesticated anaerobic granular sludge is placed in the methane production reaction device, and the domesticated anaerobic granular sludge accounts for about half of the total volume of the methane production reaction device after being added and placed still; and (3) adjusting the pH of the upper liquid part to 7.0 after electrolysis, then feeding the upper liquid part into UASB (upflow anaerobic sludge blanket), and generating acetic acid, hydrogen and carbon dioxide by organic matters in a methanogenic reactor under the action of acid-producing bacteria, and then converting the acetic acid, the hydrogen and the carbon dioxide into methane by the methanogenic bacteria.)

1. A method for recycling pyroligneous acid is characterized by comprising the following steps:

(1) preparing wood vinegar;

taking peanut shells as raw materials, condensing the flue gas produced by biomass carbon by a thermal cracking method, collecting 100-450 ℃ flue gas condensate, and standing for later use;

(2) pre-separating and removing oil;

putting the wood vinegar liquid in a refrigerator at 4 ℃ for 24 hours, and separating to remove the upper oily matter; the concentration of acetic acid in the separated water phase is 53000 mg/L, COD is 110000 mg COD/L, and pH is 3.5;

(3) diluting;

diluting the wood vinegar to different concentrations of 4000mg COD/L, 6000 mg COD/L and 8000 mg COD/L, inspecting the methane production condition of the wood vinegar under different concentrations, determining the gas production inhibition effect and corresponding concentration according to the fermentation result, and taking the concentration as the research object of the electrolysis experiment;

(4) electrolyzing wood vinegar with three-dimensional iron carbon;

the three-dimensional electrolysis system selects a stainless steel electrode as an anode material, a graphite electrode as a cathode material, and wooden columnar activated carbon and iron powder as diffusion electrodes; the direct current voltage stabilizer provides a stable direct current power supply for the electrolysis system; adding the diluted pyroligneous liquor to be treated into a reaction tank, controlling the electrolysis degree by controlling the voltage, the electrolysis time and the iron-carbon ratio when treating the pyroligneous liquor by the three-dimensional iron-carbon electrolysis technology, wherein the voltage range is 0-20V, the treatment time is 30-120min, the iron-carbon addition is 80-120 g/L, and the iron-carbon ratio is 1:2 to 2: 1; after pretreatment of an electrolysis system, standing to remove active carbon and residual iron powder, and taking upper-layer liquid for later use;

(5) anaerobic fermentation for producing methane

a, anaerobic granular sludge domestication: the inoculum adopts anaerobic granular sludge, the total solid matter content of which is 9.92 percent, and the volatile solid matter content of which is 72.5 percent; in order to better improve the utilization capacity of the anaerobic granular sludge to organic acid, the anaerobic granular sludge is acclimated by adopting an acetic acid solution to obtain acid-producing bacteria and methanogenic bacteria;

b, taking an upflow anaerobic sludge blanket as a methanogenesis reaction device, placing the domesticated anaerobic granular sludge into the methanogenesis reaction device, and standing the domesticated anaerobic granular sludge to be about half of the total volume of the methanogenesis reaction device; and (3) adjusting the pH of the liquid to 7.0 after the liquid part at the upper layer is electrolyzed, then feeding the liquid into an upflow anaerobic sludge bed, and generating acetic acid, hydrogen and carbon dioxide by organic matters in a methanogenic reaction device under the action of acid-producing bacteria, and then converting the acetic acid, the hydrogen and the carbon dioxide into methane by the methanogenic bacteria.

2. The method of claim 1, wherein effluent from the upflow anaerobic sludge blanket is used to condition dilute wood vinegar.

3. The method for recycling pyroligneous acid as claimed in claim 1, which comprises the steps ofStep (5) the formula of the acetic acid solution in the step a for acclimatization of anaerobic granular sludge is as follows: sodium acetate is used as a carbon source, the adding amount is 2000 mg COD/L, and NH is respectively used as a nitrogen source and a phosphorus source₄Cl and KH₂PO₄Provided that the COD is N: P =200:5:1, and the other trace element formulas are shown in the table below; the other nutrient elements for domesticating the granular sludge are composed of mg/L, and the adding proportion is 1 mL/g COD microelement;

4. the method for recycling pyroligneous liquor according to claim 1, wherein the diameter of the woody columnar activated carbon is 1.5 mm, the packing density is 550 g/L or less, and the iodine value is 600 mg/g or more.

Technical Field

The invention relates to a technology for utilizing wood vinegar, in particular to a method for recycling wood vinegar.

Background

The pyroligneous liquor is an organic liquid component obtained by condensing, recovering and separating gas generated in the biomass pyrolysis carbonization process. The components are complex, mainly acid, phenol, nitrogen-containing hybrid compounds, ketone and aldehyde organic matters, and also contain partial alcohol, ester, amine substances and the like. According to the functional characteristics of the components, the wood vinegar is mainly used as a plant growth promoter, a bacteriostatic agent, compost, a feed additive, a food additive and the like at present, the development of the wood vinegar utilization way has important significance for improving the added value of the wood vinegar, and relevant reports of preparing biogas by the wood vinegar are not found through consulting documents, patents and other data.

Disclosure of Invention

The invention aims to provide a method for efficiently recycling pyroligneous liquor, namely a method for preparing biogas by intensively treating pyroligneous liquor wastewater by combining a three-dimensional iron-carbon electrolysis technology and anaerobic fermentation. Aiming at the characteristic of complex components in the pyroligneous liquor, the three-dimensional iron-carbon electrolysis technology is adopted to decompose toxic substances such as phenols, pyridines and the like, the technology mainly adopts granular activated carbon with large specific surface area and zero-valent iron as granular electrodes, can provide more active reaction sites to improve the mass transfer rate, and micro electrolytic cells formed by a plurality of granular electrodes are uniformly dispersed in a reaction system through aeration and stirring actions to accelerate the degradation of the toxic substances. The main principle is the anodic generation of Fe²⁺，Fe³⁺And H generated at the cathode₂O₂The organic matter is oxidized by direct or indirect means. The biochemical utilization of the treated pyroligneous liquor is obviously improved, and the methane yield can be obviously improved under the action of anaerobic microorganisms.

In order to realize the purpose, the invention adopts the technical scheme that: a method for recycling pyroligneous liquor comprises the following steps:

(1) preparation of pyroligneous liquor

The peanut shells are used as raw materials, flue gas generated in the production of biomass carbon by the thermal cracking method is condensed to collect flue gas condensate of 100-450 ℃, and the flue gas condensate is stood for later use.

(2) Pre-separating and removing oil.

The pyroligneous liquor was kept in a refrigerator at 4 ℃ for 24 hours, and the upper oily matter was separated and removed. The concentration of acetic acid in the separated water phase is 53000 mg/L, COD is 110000 mg COD/L, and pH is 3.5.

(3) And (6) diluting.

Diluting the wood vinegar liquid to different concentrations (4000 mg COD/L, 6000 mg COD/L and 8000 mg COD/L), inspecting the methane production condition of the wood vinegar liquid under different concentrations, determining the gas production inhibition effect and corresponding concentration according to the fermentation result, and taking the concentration as the research object of the electrolysis experiment.

(4) Three-dimensional iron-carbon electrolysis treatment of wood vinegar.

The three-dimensional electrolysis system selects a stainless steel electrode as an anode material, a graphite electrode as a cathode material and wooden columnar activated carbon and iron powder as diffusion electrodes. The direct current voltage stabilizer provides a stable direct current power supply for the electrolysis system. Adding the wood vinegar with the concentration inhibited in the step (2) into a reaction tank, controlling the electrolysis degree by controlling parameters such as voltage, electrolysis time, iron-carbon ratio and the like when treating the wood vinegar by using a three-dimensional iron-carbon electrolysis technology, wherein the voltage range is 0-20V, the treatment time is 30-120min, the iron-carbon addition amount is 80-120 g/L, and the iron-carbon ratio is 1:2 to 2: 1. after the pretreatment of the electrolysis system, standing to remove the active carbon and the residual iron powder, and taking the upper liquid for later use.

(5) Anaerobic fermentation for producing methane

a, anaerobic granular sludge domestication: the inoculum was anaerobic granular sludge with a total solid matter content of 9.92% and volatile solid matter content of 72.5%. In order to better improve the utilization capacity of the anaerobic granular sludge to organic acid, the prepared acetic acid solution is adopted to domesticate the anaerobic granular sludge to obtain acid-producing bacteria and methanogenic bacteria with higher reaction activity.

b, adopting an up-flow anaerobic sludge bed (UASB) as a methanogenesis reaction device, placing the domesticated anaerobic granular sludge into the methanogenesis reaction device, and standing the domesticated anaerobic granular sludge to be about half of the total volume of the methanogenesis reaction device. And (3) electrolyzing the upper layer liquid part to mainly obtain short carbon chain organic acids such as acetic acid, propionic acid, butyric acid and the like and generated small molecular organic matters, adjusting the pH of the liquid to 7.0, then feeding the liquid into UASB (upflow anaerobic sludge blanket), and generating acetic acid, hydrogen and carbon dioxide by the organic matters in a methane-generating reaction device under the action of acid-producing bacteria, and then converting the acetic acid, the hydrogen and the carbon dioxide into methane by the methane-producing bacteria.

The method is particularly characterized in that effluent water in the methanogenesis reaction device is used for adjusting and diluting the pyroligneous liquor, and the concentration of organic matters in the pyroligneous liquor is changed through dilution, so that the UASB feeding load is adjusted.

The anaerobic granular sludge domestication is characterized in that the sludge is domesticated by adopting a prepared acetic acid solution, and the formula is as follows: sodium acetate is used as carbon source (2000 mg COD/L), and NH is respectively used as nitrogen source and phosphorus source₄Cl and KH₂PO₄Provided that the COD is N: P =200:5:1, and the other trace element formulations are as shown in the table below. Other nutrient elements (mg/L) for domesticating the granular sludge are added according to the proportion of 1 mL/g COD trace elements.

The diameter of the wooden columnar activated carbon is 1.5 mm, the packing density is less than or equal to 550 g/L, and the iodine value is more than or equal to 600 mg/g. The grain sizes of the high-purity iron powder with different specifications are 40 meshes, 100 meshes and 200 meshes respectively.

The invention has the beneficial effects that: (1) the utilization value of the existing wood vinegar is low, methane is not found in the wood vinegar through direct anaerobic fermentation without treatment, and the inhibition or toxicity effect of partial organic matters in the wood vinegar on microorganisms is proved. According to the invention, the three-dimensional iron-carbon electrolysis technology is coupled with anaerobic fermentation to carry out energy utilization on the wood vinegar liquid, so that clean gas fuel-methane can be obtained, and the application approach is widened while the existing application value of the wood vinegar liquid is obviously improved. (2) The invention controls the degradation degree of different components by adjusting main parameters in the three-dimensional iron carbon electrolysis process, realizes the conversion of macromolecular toxic substances which are difficult to degrade to micromolecular substances, reduces the loss of effective components, has the COD removal rate of only 11 percent, and improves the biological generation rate of the wastewater by utilizing a substrate directional regulation and control technologyChemical property, and effectively recovering the energy contained in the pyroligneous liquor. (3) The upper layer liquid obtained by standing after three-dimensional electrolytic treatment contains Fe²⁺And a small amount of suspended C powder, Fe³⁺The active carbon has a promoting effect on the activity of methanogens, can be used as a carrier for directly transferring electrons between inoculations to improve the conversion efficiency and the gas production rate of acid, and in addition, the adsorption performance of the active carbon can act on a small amount of residual toxic substances to reduce the negative effect on microorganisms, and compared with a control group which is not subjected to electrolysis treatment, the gas production rate can be improved by 110 percent at most. (4) After the pyroligneous is treated by three-dimensional iron-carbon electrolysis, the pH value is increased from initial 3.5 to about 6.5, and compared with the direct fermentation of the pyroligneous, the alkali amount required by the initial pH adjustment in the anaerobic fermentation process can be reduced. (5) The wood vinegar treated by UASB can be used as dilution water, so that the addition of external water source can be reduced, and simultaneously, the secondary treatment is carried out on the organic matters which are not completely degraded, and the degradation degree and the gas yield of the substrate are improved.

Detailed Description