CN111549077B - Method for producing organic acid and converting methane by regulating and controlling degradation of silage straws by using black liquor - Google Patents
Method for producing organic acid and converting methane by regulating and controlling degradation of silage straws by using black liquor Download PDFInfo
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Abstract
A method for producing organic acid and converting methane by regulating and controlling degradation of silage straws by using black liquor is characterized by comprising the following steps: (1) preparing raw materials; the silage straw is obtained by crushing fresh corn straw; the black liquor is papermaking black liquor; (2) and (4) domesticating microorganisms. (3) Acid-producing fermentation with high solid concentration; controlling the pH value of the percolate to be 8 all the time, keeping the fermentation temperature to be 35 ℃, continuously percolating and degrading organic components in the straws under the action of microorganisms, and finally obtaining the percolate rich in organic acid after the retention time is 5 days; (4) methane conversion of the end product of the acid production phase in the methane production phase; the organic load rate of the system is gradually increased by adopting a gradient load mode, the system is operated for 10d under each load condition, and the percolate is continuously fermented in an upflow anaerobic sludge bed of a methanogenesis reactor to generate methane and carbon dioxide.
Description
Technical Field
The invention relates to the field of organic waste resource utilization, in particular to a method for producing organic acid by regulating and controlling degradation of silage straws and producing methane from mixed liquor by using black liquor.
Background
The straw is used as a large amount of byproducts in agricultural production, and the comprehensive utilization of the straw is concerned. Because the anaerobic digestion technology can realize the energy recovery of organic matters in the straws, the anaerobic digestion technology is generally applied as an organic solid waste cleaning and energy utilization technology in the practical process. The process adopted in the project at present mainly adopts single-phase fermentation, but the large-scale development of the biogas project is severely restricted due to the influence of factors such as fermentation concentration, slag bonding and floating, large biogas amount and the like, so that the scheme of the two-phase process is gradually and widely researched and popularized. The yield of the organic acid in the acid-producing phase in the process is directly related to the volumetric gas production rate of the whole process, and the optimization and matching of process links are urgently needed to improve the production and metabolism capacity of the target product of the acid-producing phase. Black liquor is high-concentration polluting wastewater generated in the paper-making process, contains a large amount of suspended solids, organic pollutants and toxic substances, and can cause serious pollution when directly discharged into a water body. The main hazards are: the wastewater containing a large amount of pigments and inorganic salts can turn the water body black and has special foul smell; the chemical oxygen demand (BOD) of the black liquor containing high-concentration organic pollutants reaches 10000-. If not properly handled, can pose a serious threat to the environment.
Disclosure of Invention
The invention aims to combine the black liquor with anaerobic fermentation acidification of ensiled straws, develop a process capable of realizing efficient degradation of the ensiled straws and effectively treating organic pollutants in the black liquor, and provide an important reference method for practical production.
In order to realize the purpose, the invention adopts the technical scheme that: a process for realizing efficient degradation of straws and effectively treating organic pollutants in black liquor comprises the following steps:
(1) preparing raw materials; the silage straw is obtained by crushing fresh corn straw; the black liquor is papermaking black liquor.
(2) Domesticating microorganisms; adopting a mixture of straws and black liquor to acclimate anaerobic sludge, setting the mass concentration of the straws in fermentation liquor to be 1 percent, setting the COD concentration of the black liquor to be 0.2 gCOD/L, and respectively using NH as a nitrogen source and a phosphorus source4Cl and KH2PO4The method provides a method which satisfies the COD that N is P =100:5:1, the raw material and the inoculum are placed in a serum bottle with the effective working volume of 1L to be cultured for 30 days (a fermentation period) under the condition of medium temperature (35 ℃), the gas production condition is observed, and the raw material and the inoculum is used as the inoculum of the acid production phase and the methane production phase of the silage straw after the process is repeated for 4 periods.
(3) And (3) acid production and fermentation with high solid concentration.
The sludge is heated at 90 ℃ for 30 minutes, methanogenic bacteria are killed, and then the sludge is used as an inoculum, and the inoculation is carried out according to the proportion of straw Volatile Solids (VS) =1: 4. A1L percolation bed reactor (LBR) is adopted as an acid production device, 100g ensiled straws, 50g sludge and 200mL water are uniformly mixed and then placed in a reactor, and the pH value is 4.5 after mixing because organic acids such as lactic acid can be generated in the ensiling process. The black liquor needs to be boiled and concentrated to one half of the original volume, the pH of leachate in the initial stage is adjusted to 8 by using the concentrated black liquor, then a peristaltic pump is started to drive the leachate to start the acid production process by percolation from top to bottom through an LBR device, the leachate is collected at the bottom of an acid production reactor, the pH is reduced due to continuous generation of organic acid, the pH value of the collected leachate is controlled by continuously feeding the black liquor through a pH automatic control liquid adding machine (CPH-1A, Changsha Croma medicine and technology Limited company), the pH of the leachate is always controlled to be 8, the fermentation temperature is kept to be 35 ℃ through a water bath jacket, organic components in straws are subjected to continuous percolation degradation under the action of microorganisms, the retention time is 5 days, meanwhile, partial refractory components in the black liquor are subjected to biotransformation, and the leachate rich in organic acid is finally obtained.
(4) The end product of the acid-producing phase is converted into methane in the methane-producing phase.
Diluting a liquid-phase end product after acidogenic fermentation into different organic loads (1 gCOD/L, 2gCOD/L, 3 gCOD/L, 4gCOD/L, 6 gCOD/L, 8 gCOD/L, 9 gCOD/L and 10 gCOD/L), adjusting the pH value to 7, keeping the fermentation temperature of a water bath jacket at 35 ℃, gradually increasing the organic load rate of the system by adopting a gradient load mode, lifting the system into a methane-producing reactor Upflow Anaerobic Sludge Bed (UASB) filled with domesticated granular sludge and having an effective working volume of 2L by using a peristaltic pump, and keeping the hydraulic retention time at 24 hours by controlling the rotating speed of the pump, and (3) operating for 10 days under each load condition, continuously fermenting the percolate rich in organic acid and partial black liquor residual components in the UASB to generate methane and carbon dioxide, and adjusting the water demand and load of the UASB effluent in the whole fermentation process link.
The invention is characterized in that the invention mainly uses the anaerobic digestion of the ensiled corn stalks to produce acid and methane to be converted into the main raw materials, the raw materials mainly relate to the ensiled corn stalks and black liquor, wherein the ensiled stalks are provided by Shandong Leling Shengli new energy resource Limited liability company, and the fresh corn stalks are crushed into 1-2cm and then stacked and hermetically stored.
The papermaking black liquor is provided by biological base materials of the university of Qilu industry and key laboratories of the green papermaking country, and is high-concentration organic wastewater which is obtained by adopting a sulfite pulping process and takes corn straws as a raw material and is rich in lignin derivatives.
The anaerobic sludge is taken from an anaerobic fermentation device for sugar-making wastewater of Shandong starlight sugar industry Co.
The method has the advantages that the alkalinity of the black liquor is utilized to regulate and control the pH value of the ensiled straw in the anaerobic acid production process, the degradation degree of cellulose and hemicellulose is improved, and therefore high organic acid yield is obtained.
1. The ensiled straws show positive effects on improving the degradation of the substrate and the accumulation of organic acid by regulating and controlling the pH value of the percolate in the acid production phase of the two-phase process, and the acid production rate is improved by 218 percent compared with the acid production rate of dry straws under the condition of controlling the pH value, which indicates that the acid production process of the ensiled straws can be strengthened by alkaline pH control; compared with ensiling straw without controlling the pH value, the yield of the organic acid is improved by 191.7 percent, and the specific reasons comprise: (1) when the pH value is in an alkaline range, lignin and hemicellulose, ester bonds, ether bonds and the like between the hemicellulose and the cellulose can be destroyed, and the contact between microorganisms and substrates is facilitated; (2) the alkaline pH can reduce the concentration of free acid, thereby reducing the inhibition of acid-producing bacteria; (3) the pH is closely linked to the distribution of functional cellulose-degrading microorganisms. The joint acid-producing metabolic products of the ensiled straws and the black liquor and organic components in the black liquor which are not utilized are efficiently converted in a certain load range in a methane-producing reactor, and the methane yield can reach 301 mLCH4The cumulative methane production volume increased by 5% compared to that produced with sodium hydroxide. However, when the black liquor is adopted, the pH value of the leachate is always controlled to be 8, and if the pH value is too high, the content of the components which are difficult to degrade in the acid production liquid is increased due to the addition of the black liquorThe amount is correspondingly increased, so that the subsequent methane production process has the problems of reduced organic load rate and reduced gas production rate.
2. The production of organic acid in acid-producing fermentation can obviously reduce the pH value of percolate, so that the consumption of alkali liquor is large, the alkaline characteristics of waste water-black liquor produced in the paper-making process are fully utilized, and the pH value of a system is properly adjusted after concentration, so that the addition of an external alkali source is reduced in the whole acid-producing process, the utilization approach of the black liquor is widened, the cost of applying the pH regulation and control technology to biogas engineering is reduced, and the economic efficiency of the engineering is improved. The necessary concentration of black liquor can obviously reduce the adjusting dosage and avoid the reduction of the concentration of the acidification product caused by excessive water addition.
3. In the whole acid production process, the black liquor is used as an alkaline regulator, and because the black liquor contains a large amount of lignin degradation products and the like, the black liquor is mostly aromatic compounds and has strong toxicity to microorganisms, and the microorganisms existing in anaerobic sludge at present have poor tolerance and utilization capacity to the substances, the domesticated microorganisms are utilized to obtain the enrichment of functional floras in the ensilage straw acid production process, organic matters in the black liquor are synchronously converted, and the acid production rate (13 percent higher than that when NaOH is used as the regulator) and the resource utilization value are further improved.
4. The concentration of the black liquor is too high, the difficulty is very high when the black liquor is directly biologically treated, so the black liquor needs to be diluted when the black liquor is treated, the black liquor is diluted to a certain extent when the black liquor is used as an alkaline regulator and is co-produced with silage straws to produce acid, the toxic effect on microorganisms is avoided being directly utilized, and the degradation possibility of components in the black liquor is improved.
5. Compared with the full-mixing fermentation process, the percolation fermentation process ensures that the high-concentration organic acid and the black liquor can not contact with the microorganisms for a long time, thereby reducing the product feedback inhibition of the organic acid on the microorganisms and the toxic effect of the black liquor on the microorganisms; the two-phase process can improve the fermentation concentration, shorten the fermentation period to 6 days (producing acid for 5 days and producing methane for 1 day), realize the recycling of water in the whole process, and avoid the problems of straw scum crusting, large biogas slurry amount, long period and the like in the single-phase process. Finally, the methane content in the biogas is up to more than 80%, the biogas heat value is improved, a higher-quality raw material gas is provided for subsequent purification, and the energy consumption is reduced.
Detailed Description
Example 1: a process for realizing efficient degradation of straws and effectively treating organic pollutants in black liquor comprises the following steps: and (4) investigating the fermentation conditions of acid production and methane production of the ensiled straws when the pH of the leachate is controlled to be 8 by using the black liquor.
(1) And (4) preparing raw materials.
The invention mainly converts silage corn straws into acid and methane through anaerobic digestion, and raw materials mainly relate to silage corn straws and black liquor, wherein the silage corn straws are provided by Shandong Leling Shengli new energy resource Limited liability company, and fresh corn straws are crushed to 1-2cm and then stacked and hermetically stored. The papermaking black liquor is provided by biological base materials of the university of Qilu industry and key laboratories of the green papermaking country, and is high-concentration organic wastewater which is obtained by adopting a sulfite pulping process and takes corn straws as a raw material and is rich in lignin derivatives.
(2) And (4) domesticating microorganisms.
In order to better improve the adaptability and the utilization capacity of the sludge to a substrate, the anaerobic sludge (obtained from anaerobic fermentation device of sugar-making wastewater of Shandong starlight sugar industry Co., Ltd.) is acclimatized by adopting a mixture of straws and black liquor (the mass concentration of the straws in fermentation liquor is set as 1 percent, and the COD concentration of the black liquor is set as 0.2 gCOD/L), and a nitrogen source and a phosphorus source are respectively treated by NH4Cl and KH2PO4The method provides that the method satisfies the COD that N: P =100:5:1, the raw material and the inoculum are placed in a 1L serum bottle to be cultured for 30 days (one fermentation period) under the condition of medium temperature (35 ℃), the gas production condition is observed, and the raw material and the inoculum is used as the inoculum of the acid production phase and the methane production phase of the silage straw after the process is repeated for 4 periods.
(3) And (3) acid production and fermentation with high solid concentration.
The sludge is heated for 30 minutes at 90 ℃ and is used as an inoculum after killing methanogenic bacteria. An infiltration bed reactor (LBR) with an effective working volume of 1L is adopted as an acid production device, 100g of ensiled straws, 50g of domesticated sludge and 200mL of water are uniformly mixed and then placed in a reactor, and the pH value is 4.5 after mixing because organic acids such as lactic acid can be generated in the ensiling process. The black liquor needs to be boiled and concentrated to one half of the original volume, the pH of leachate in the initial stage is adjusted to 8 by using concentrated black liquor, then a peristaltic pump is started to drive the leachate to start the acid production process by percolation from top to bottom from an LBR device, the leachate is collected at the bottom of an acid production reactor, the pH of the leachate is collected and is reduced due to continuous generation of organic acid, the pH value of the leachate is controlled by continuously feeding black liquor through a pH automatic control liquid adding machine (CPH-1A, Changsha Croma medicine science and technology Limited company), the pH value of the leachate is always controlled to be 8, the fermentation temperature is kept to be 35 ℃, organic components in straws are continuously percolated and degraded under the action of microorganisms, the retention time is 5 days, and meanwhile, part of difficultly degraded components in the black liquor are subjected to biotransformation, finally obtaining the leachate rich in organic acid. The organic acid yield was calculated to be 0.35 grams of volatile organic acid per gram of volatile solid.
(4) Conversion of the acid-producing phase product in the methanogenic phase.
In order to examine the methane conversion utilization of the liquid phase end product of the acid-producing phase, a methane-producing reactor was coupled thereto to evaluate the methane conversion effect of the product. Adding water into the percolate to dilute the percolate to 1gCOD/L, adjusting the pH value to 7, driving an acid production liquid by a peristaltic pump to enter a methane production reactor Upflow Anaerobic Sludge Blanket (UASB) with an effective working volume of 2L for continuous fermentation, controlling the hydraulic retention time to be 24 hours by adjusting the rotating speed of the pump, keeping the fermentation temperature of a water bath jacket at 35 ℃, fermenting under the action of granular sludge in the UASB to generate methane and carbon dioxide, gradually increasing the water inflow of the UASB to 2gCOD/L, 3 gCOD/L, 4gCOD/L, 6 gCOD/L, 8 gCOD/L, 9 gCOD/L and 10 gCOD/L after 10 days of operation, operating 10 days of each load, and observing the gas production condition. The results show that the gas production is normal when the water inlet load is less than or equal to 9 gCOD/L in the test load range, and the methane yield is 301 mLCH when the water inlet load is equal to 9 gCOD/L4The methane content reaches 80.9 percent. When the water inlet load is increased to 10 gCOD/L, the load bearing capacity of the system is exceeded, so that the gas production rate is increasedThe methane yield is only 195 mLCH4/gCOD。
Example 2: in this embodiment, the same points as those in example 1 are not repeated, except that the pH value of the leachate adjusted by using black liquor in step (3) is changed from 8 to 10, and as a result, it is found that the yield of organic acid in the acid production process is 0.37 g of volatile organic acid/g of volatile solid, and compared with that in example 1, the pH control range is increased, so that the yield of organic acid is increased. But when the acidogenic phase product is subjected to methane conversion, the organic load rate is reduced, and the methane yield is obviously reduced to 219 mLCH at 6 gCOD/L4(ii)/gCOD. This indicates that the addition of too much black liquor at higher pH results in more refractory components in the acid-producing liquor, thereby causing the components in the black liquor to have a toxic effect on the microorganisms.
Example 3: the same points as those in example 1 are not repeated, except that the pH of the leachate adjusted by using black liquor in step (3) is changed from 8 to 7, and as a result, it is found that the yield of organic acid in the acid production process is 0.18 g of volatile organic acid/g of volatile solid, and the acid production rate is significantly lower than that in example 1. Controlling the leachate pH to 7 is not suitable because the acid yield directly affects the methane yield of the two-phase process.
Example 4: the same points as those in example 1 are not repeated, except that the pH of the leachate adjusted by using black liquor in step (3) is changed from 8 to 6, and as a result, the yield of organic acid in the acid production process is 0.11 g of volatile organic acid/g of volatile solid, and the acid production rate is significantly lower than that in examples 1 and 2. Indicating that the pH value of the percolate is not suitable to be controlled in an acidic range.
From examples 1-4, it can be seen that the black liquor is not suitable for being too high or too low when used for adjusting the pH value of the silage straw leachate, otherwise the organic load rate or the acid production rate in the methane production phase is low, and the anaerobic fermentation system cannot normally operate.
Example 5: the same parts of this example as example 1 are not described again, except for the consideration of acid-producing fermentation of ensiled stalks when pH is not controlled. The leachate pH value in (3) in example 1 is not controlled at all, acid production metabolism is always carried out according to natural fermentation conditions, the rest conditions are the same as the operation in example 1, and the yield of the finally obtained organic acid is 0.12 g of volatile organic acid/g of volatile solid. By comparison with example 1, pH control in the acidogenic metabolism of ensiled straw had a significant impact on substrate degradation and organic acid accumulation.
Example 6: the same points as those in example 1 are not repeated, except that NaOH is used to adjust the pH of leachate to 10, and the rest of the operations are the same as those in example 1, and as a result, it is found that the yield of organic acid in the acid production process is 0.38 g of volatile organic acid/g of volatile solid, which is not much different from that in example 2, indicating that pH adjustment to 10 is beneficial to acid production metabolism of substrate. But the leachate obtained in the acid production phase is gradually improved by the load, when the organic load rate reaches 10 gCOD/L, the methane content in the biogas reaches 81.1 percent, and the methane yield is 305 mLCH4The load of the/gCOD is greatly improved compared with that of the example 2, which shows that the black liquor and NaOH are obviously different, and the addition of excessive black liquor has certain negative effect on methane conversion, and can seriously affect the conversion of organic acid in a methane-producing phase.
Example 7: the same parts of this example as example 1 are not described again, except that the acid-producing fermentation of ensiled straw is considered when using the NaOH alkaline regulator.
Steps (1) and (2) were conducted in the same manner as in (1) and (2) in example 1. And (4) adjusting the pH value of the 6mol/L NaOH solution in the step (3) to 8. In this example, there is no contribution of organic acid in the final product from the degradation of organic matter in black liquor, and the yield of organic acid obtained is 0.33 g volatile organic acid/g volatile solid, which is lower than that in example 1.
And (4): producing methane. As in step (4) in example 1, when the water loading was 8 gCOD/L, the methane yield was 307 mLCH4the/gCOD, and the cumulative methane production volume is reduced by 5% compared to example 1, which indicates that the components in the black liquor and their metabolic products in the acidogenic phase in example 1 have a certain contribution to the methanogenic process in example 1.
Example 8: the black liquor is directly used for anaerobic fermentation. Adopting a 500mL serum bottle as a fermentation device, adding 350mL papermaking black liquor mother liquor, inoculating the domesticated microorganism in the embodiment 1 according to the ratio of 1:1 of inoculum to substrate volatile solid matter, adjusting the pH value from 14 to 7 by using 6mol/L hydrochloric acid solution, placing the domesticated microorganism in a 35 ℃ water bath kettle, observing the gas production condition, finding that methane is not produced all the time from the 1 st day to the 20 th day, and detecting no organic acid in the system, which indicates that the black liquor mother liquor has poor biochemical utilization performance and is difficult to be effectively converted and utilized by the microorganism at high concentration.
Example 9: the same parts of this example as example 1 will not be described again, except that the acid-producing fermentation of dry straw was examined when the pH was controlled by black liquor.
The ensiled straw in example 1 was replaced with dry straw and steps (1) and (2) were the same as those of (1) and (2) in example 1. In the step (3), 30g of dry straws and 50g of domesticated sludge are uniformly mixed and then placed in a reactor, 270mL of water is added in the initial stage, the pH value is adjusted to 8 by using black liquor, percolation is started, and the yield of the finally obtained organic acid is 0.11 g of volatile organic acid/g of volatile solid, which indicates that when the pH value is controlled to 8, the dry straws do not show the same acid production characteristic as the ensiled straws, and because microorganisms and the generated acid play a certain pretreatment role on the straws in the ensiling process, and the dry straws cannot achieve a better acid production effect only by pH regulation without any treatment due to an anti-degradation barrier generated by a complex structure of the straws.
Example 10: the same parts of this example as example 1 are not repeated, except that the continuous fermentation in step (4) in example 1 is changed into batch fermentation, 1000ml of serum bottle is used as a fermentation device, 20g/L of acclimated sludge is inoculated, the effective working volume is 750ml, the acid-producing phase products in example 1 are added to the concentrations of 1gCOD/L, 2gCOD/L, 3 gCOD/L and 4gCOD/L, the acetic acid fermentation experiment with the same load is used as a contrast at the same time, the methane production conditions of the acid-producing liquid of black liquor and ensiled straws are observed, the fermentation temperature in a water bath is kept at 35 ℃, and the result shows that the methane conversion of the acid-producing liquid is obviously reduced when the load is 4gCOD/L, and the methane yield is that201 mLCH4The fact that the control group of acetic acid fermentation produces gas normally indicates that the black liquor contains substances which have inhibitory effect on anaerobic fermentation microorganisms. Therefore, the continuous fermentation is carried out by adopting a mode of gradient load increase, the UASB inflow water is gradually increased from 1gCOD/L to 10 gCOD/L, the methane accumulation is normal, and the methane yield is 301 mLCH when the inflow load is 9 gCOD/L4(ii)/gCOD. The continuous increase of the load gas production is inhibited, but the organic load rate in the fermentation process is obviously increased compared with the conventional batch fermentation.
Example 11: this example is the same as example 1 except that a mixed stirred tank reactor (CSTR) was used as the acid generator instead of the infiltration bed (LBR), and the operation was the same as in example 1. Compared with the example 1, the acid production rate in the acid production phase is obviously reduced to 0.15 g of volatile organic acid/g of volatile solid, because the feedback inhibition of the organic acid in the acid production phase on the product generated by the activity of the microorganism is realized when the substrate, the inoculum and the fermentation liquor are mixed and fermented, so that the degradation of the substrate is seriously influenced, and the percolation bed as an acid production device can reduce the effect of the product on the microorganism when the straw is fermented at high solid concentration, thereby realizing higher organic acid yield.
Claims (3)
1. A method for producing organic acid and converting methane by regulating and controlling degradation of silage straws by using black liquor is characterized by comprising the following steps:
(1) preparing raw materials; the silage straw is obtained by crushing fresh corn straw; the black liquor is papermaking black liquor, the black liquor is high-concentration organic wastewater obtained by using corn straws as a raw material and adopting a sulfite pulping process, and the high-concentration organic wastewater is rich in lignin derivatives;
(2) domesticating microorganisms; adopting a mixture of straws and black liquor to acclimate anaerobic sludge, setting the mass concentration of the straws in fermentation liquor to be 1 percent, setting the COD concentration of the black liquor to be 0.2 gCOD/L, and respectively using NH as a nitrogen source and a phosphorus source4Cl and KH2PO4Provided that the COD N: P =100:5:1 was satisfied, and the raw material and the inoculum were cultured in a 1L serum bottle at 35 ℃ for 30 daysObserving the gas production condition for a fermentation period, and repeatedly carrying out the fermentation period for 4 periods to serve as inoculants of an acid production phase and a methane production phase of the ensiled straws;
(3) acid-producing fermentation with high solid concentration;
heating the sludge at 90 ℃ for 30 minutes to kill methanogenic bacteria and then taking the killed methanogenic bacteria as an inoculum; inoculating according to the proportion of straw Volatile Solid (VS) =1: 4; a 1L percolation bed reactor is adopted as an acid production device, 100g ensiled straws, 50g sludge and 200mL water are uniformly mixed and then placed in the reactor, and the pH value is 4.5 after mixing because organic acids such as lactic acid can be generated in the ensiling process; the black liquor needs to be boiled and concentrated to one half of the original volume, the leachate is adjusted to pH 8 by the concentrated black liquor in the initial stage, then a peristaltic pump is started to drive the leachate to start the acid production process from top to bottom by the percolation reactor, the leachate is collected at the bottom of the acid production reactor, and the pH is reduced due to continuous generation of organic acid, so that the pH value of the leachate is controlled by continuously feeding the black liquor by a pH automatic control liquid adding machine, the pH of the leachate is always controlled to be 8, the fermentation temperature is kept to be 35 ℃, organic components in the straw are continuously percolated and degraded under the action of microorganisms, the retention time is 5 days, meanwhile, part of the components difficult to degrade in the black liquor are subjected to biological conversion, and the leachate rich in organic acid is finally obtained;
(4) methane conversion of the end product of the acid production phase in the methane production phase;
diluting the liquid-phase end product after acid-producing fermentation into different organic loads: 1gCOD/L, 2gCOD/L, 3 gCOD/L, 4gCOD/L, 6 gCOD/L, 8 gCOD/L, 9 gCOD/L, 10 gCOD/L, adjusting pH to 7, the fermentation temperature to 35 ℃, gradually increasing the organic load rate of the system by adopting a gradient load mode, lifting the system to a methane-producing reactor upflow anaerobic sludge bed filled with domesticated granular sludge by using a peristaltic pump, keeping the hydraulic retention time for 24 hours by controlling the rotating speed of the pump, operating for 10 days under each load condition, continuously fermenting percolate rich in organic acid and partial black liquor residual components in the upflow anaerobic sludge bed of the methane-producing reactor to generate methane and carbon dioxide, and enabling the effluent of the upflow anaerobic sludge bed of the methane-producing reactor to be used for water demand and load adjustment in the whole fermentation process link.
2. The method for regulating and controlling the degradation of silage straws and conversion of methane by using black liquor as claimed in claim 1, wherein the anaerobic sludge is obtained from an anaerobic fermentation device for sugar-making wastewater.
3. The method for producing organic acid and converting methane by using black liquor to regulate and control the degradation of silage straws as claimed in claim 1, wherein the silage straws are prepared by crushing fresh corn straws into 1-2cm, stacking, and hermetically storing.
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