A method for simultaneous source and end-of-pipe treatment of ethanol biorefining and acid mine wastewater

Abstract

This invention provides a method for the simultaneous source-to-end treatment of ethanol biorefining and acidic mine wastewater, comprising: 1) mixing lignocellulosic biomass and acidic mine wastewater, and performing solid-liquid separation of the treated slurry; 2) washing the solid residue obtained in step 1) to neutrality, adding buffer solution and cellulase, performing enzymatic hydrolysis, and then performing solid-liquid separation to obtain filter residue and filtrate capable of ethanol fermentation; 3) mixing the filter residue from step 2) with sodium hydroxide solution, performing solid-liquid separation after treatment, and then performing lignin solution and pyrite passivation treatment, performing solid-liquid separation after reaction, and freeze-drying to obtain passivated pyrite. The method utilizes AMD pretreatment of lignocellulosic biomass to produce bioethanol, achieving green recycling of resources; the hemicellulose remaining in the AMD serves as a carbon source for SRB, achieving sulfate reduction and heavy metal removal in the AMD; and the lignin is also used to passivate sulfide ores, achieving simultaneous source-to-end treatment of AMD.

Description

Technical Field

[0001] This invention relates to the fields of wastewater treatment technology and ethanol biorefining technology, and particularly to a method for simultaneously treating acidic mine wastewater at both the source and end of the process, coupled with ethanol biorefining. Background Technology

[0002] Biofuels have become an attractive alternative to fossil fuels due to their renewable nature, with bioethanol being the most common biofuel product. First-generation bioethanol primarily utilizes glucose extracted from edible starch as a raw material, posing a threat to food supplies. To address this conflict, the focus has shifted to utilizing inedible and renewable lignocellulosic biomass. However, due to the recalcitrant nature of lignocellulosic biomass, its conversion into fermentable sugars typically requires pretreatment. Dilute acid pretreatment is highly efficient and relatively inexpensive, thus gaining widespread industrial application. However, dilute acid pretreatment often results in wastewater streams rich in H₂SO₄ and hemicellulose-derived sugars, leading to significant wastewater treatment costs.

[0003] Acid mine wastewater (AMD) is highly acidic wastewater generated during the oxidation of sulfide minerals. It is characterized by high levels of heavy metals and sulfates, and improper management can cause severe soil and water pollution, posing a serious threat to human health. AMD management is mainly divided into two categories: end-of-pipe treatment and source control. In end-of-pipe treatment technologies, bioremediation has become an effective approach to AMD control due to its excellent remediation capabilities. This method mainly relies on sulfate-reducing bacteria (SRB) to reduce sulfates in AMD to hydrogen sulfide, but often requires expensive carbon sources. In source control technologies, surface passivation offers long-lasting preventative effects against AMD and has become a robust technology for preventing AMD formation. However, the high cost of passivating agents and the passivation process is a major obstacle to the application of surface passivation.

[0004] The combined treatment of lignocellulose and acidic mine wastewater provides a novel approach to waste management and value-added processing. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for the simultaneous source-end treatment of acid mine wastewater and ethanol biorefining coupled with acid mine wastewater. This method uses lignocellulose biomass as raw material, and after pretreatment of acid mine wastewater, converts cellulose into bioethanol through bioconversion. The hemicellulose released during the pretreatment process can serve as a carbon source for the bioremediation of AMD. The remaining lignin serves as a passivating agent, thereby achieving source treatment of AMD and realizing the full utilization of lignocellulose biomass components.

[0006] This invention provides a method for simultaneously treating the source and end of acid mine wastewater in ethanol biorefining, comprising the following steps:

[0007] 1) Mix lignocellulose biomass with acidic mine wastewater, and then perform solid-liquid separation on the treated slurry to obtain a solid residue rich in cellulose and lignin and a filtrate rich in hemicellulose.

[0008] 2) After washing the solid residue rich in cellulose and lignin described in step 1) to neutral, add buffer solution and cellulase, perform enzymatic hydrolysis, and then separate the solid and liquid to obtain filter residue and filtrate rich in fermentable sugars; inoculate the filtrate rich in fermentable sugars with brewer's yeast for ethanol fermentation.

[0009] 3) Mix the filter residue from step 2) with sodium hydroxide solution, treat and then separate the solid and liquid to obtain a lignin solution; passivate the lignin solution with pyrite, react and then separate the solid and liquid, freeze-dry to obtain passivated pyrite.

[0010] Preferably, the temperature of the treatment in step 1) is 90–120°C and the time is 1–4 hours.

[0011] Preferably, the enzymatic hydrolysis time in step 2) is 46-50 h; the enzymatic hydrolysis temperature is 45-55 °C.

[0012] Preferably, the solid content of the mixture after adding buffer and cellulase in step 2) is 10-15%;

[0013] The dosage of cellulase is 5–20 mg / g of solid residue.

[0014] Preferably, the concentration of the sodium hydroxide solution in step 3) is 0.05–0.5 mol / L; the solid content of the filter residue and the sodium hydroxide solution after mixing is 5–15%.

[0015] The buffer solution is an acetate or citrate buffer; the pH of the buffer solution is 5.0–5.5.

[0016] Preferably, in step 3), the temperature for treating the filter residue and sodium hydroxide solution after mixing is 115–125°C, and the time is 55–65 min.

[0017] Preferably, the passivation treatment temperature in step 3) is 25-30°C, and the passivation treatment time is 230-250 min.

[0018] Preferably, pyrite accounts for 1 to 2% of the mass of the lignin solution.

[0019] Preferably, the lignocellulose biomass is selected from one or more of corn cobs, corn stalks, wheat stalks, rice stalks, rapeseed stalks, and sugarcane bagasse;

[0020] The lignocellulose biomass accounts for 10-20% of the mass of the acidic mine wastewater.

[0021] Preferably, in step 1), the filtrate rich in hemicellulose is inoculated with sulfate-reducing bacteria for anaerobic culture.

[0022] This invention provides a method for the simultaneous source-to-end treatment of ethanol biorefining and acidic mine wastewater, comprising the following steps: 1) mixing lignocellulosic biomass and acidic mine wastewater, and performing solid-liquid separation on the treated slurry to obtain a solid residue rich in cellulose and lignin and a filtrate rich in hemicellulose; 2) washing the solid residue rich in cellulose and lignin from step 1) to neutrality with water, adding buffer solution and cellulase, performing enzymatic hydrolysis, and then performing solid-liquid separation to obtain filter residue and a filtrate rich in fermentable sugars; inoculating the filtrate rich in fermentable sugars with Saccharomyces cerevisiae for ethanol fermentation; 3) mixing the filter residue from step 2) with sodium hydroxide solution, treating and then performing solid-liquid separation to obtain a lignin solution; passivating the lignin solution with pyrite, reacting and then performing solid-liquid separation, and freeze-drying to obtain passivated pyrite. This invention utilizes acidic mine wastewater and renewable lignocellulosic biomass as raw materials to produce bioethanol, achieving green recycling of resources and low-cost management of AMD (Alternative Dioxide). The invention uses cellulose from lignocellulosic biomass for ethanol production, and the hemicellulose remaining in the AMD after AMD pretreatment serves as a carbon source for SRB (sulfate-reducing sulfide minerals), achieving sulfate reduction and heavy metal removal in AMD. Simultaneously, waste lignin is used to passivate sulfide minerals, achieving source control of AMD. This invention achieves full utilization of lignocellulosic biomass components, improves the utilization rate of lignocellulosic biomass, reduces waste generation, provides a new approach to AMD management, and lowers the cost of ethanol refineries. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the process for simultaneously treating the source and end of acidic mine wastewater in a specific embodiment of the present invention, involving the coupling of ethanol biorefining. Detailed Implementation

[0024] This invention provides a method for simultaneously treating the source and end of acid mine wastewater in ethanol biorefining, comprising the following steps:

[0025] 1) Mix lignocellulose biomass and acid mine wastewater (AMD), and then perform solid-liquid separation on the treated slurry to obtain a solid residue rich in cellulose and lignin and a filtrate rich in hemicellulose.

[0026] 2) After washing the solid residue rich in cellulose and lignin described in step 1) to neutral, add buffer solution and cellulase, perform enzymatic hydrolysis, and then separate the solid and liquid to obtain filter residue and filtrate rich in fermentable sugars; inoculate the filtrate rich in fermentable sugars with brewer's yeast for ethanol fermentation.

[0027] 3) Mix the filter residue from step 2) with sodium hydroxide solution, treat and then separate the solid and liquid to obtain a lignin solution; passivate the lignin solution with pyrite, react and then separate the solid and liquid, freeze-dry to obtain passivated pyrite.

[0028] This invention utilizes acidic mine wastewater and renewable lignocellulosic biomass (such as corn cobs) as raw materials to produce bioethanol, achieving green recycling of resources and low-cost management of AMD (Alternative Dioxide). The invention uses cellulose from lignocellulosic biomass (such as corn cobs) for ethanol production, and uses hemicellulose remaining in the AMD after AMD pretreatment as a carbon source for SRB (sulfate-reducing sulfide minerals), achieving sulfate reduction and heavy metal removal in AMD. Simultaneously, waste lignin is used to passivate sulfide minerals, achieving source control of AMD. This invention achieves full utilization of lignocellulosic biomass (such as corn cobs), improves the utilization rate of lignocellulosic biomass (such as corn cobs), reduces waste generation, provides a new approach to AMD management, and lowers the cost of ethanol refineries.

[0029] This invention mixes lignocellulose biomass with acidic mine wastewater, and then performs solid-liquid separation on the treated slurry to obtain a solid residue rich in cellulose and lignin and a filtrate rich in hemicellulose.

[0030] The lignocellulose biomass used in this invention is selected from one or more of corn cobs, corn stalks, wheat stalks, rice stalks, rapeseed stalks, and sugarcane bagasse; the lignocellulose biomass accounts for 10-20% of the mass of acidic mine wastewater. This invention uses acidic mine wastewater (AMD) instead of traditional dilute acid to pretreat the lignocellulose biomass, reducing the cost of pretreatment and subsequent treatment of H2SO4-rich wastewater.

[0031] In this invention, the temperature for treating the mixture of lignocellulose biomass and acidic mine wastewater is 90–120°C, and the time is 1–4 hours. The treated slurry is then subjected to solid-liquid separation to obtain a solid residue rich in cellulose and lignin and a filtrate rich in hemicellulose.

[0032] The filtrate rich in hemicellulose was inoculated with sulfate-reducing bacteria for anaerobic culture to reduce and remove sulfates and heavy metals from AMD. The inoculum size of sulfate-reducing bacteria was 20–40% (v / v).

[0033] In this invention, the solid residue rich in cellulose and lignin obtained in step 1) is washed with water until neutral, then buffer solution and cellulase are added, followed by enzymatic hydrolysis and solid-liquid separation to obtain filter residue and filtrate rich in fermentable sugars.

[0034] In this invention, the solid content of the mixture after adding buffer and cellulase is 10-15%; the buffer is an acetate or citrate buffer; the pH of the buffer is 5.0-5.5. The amount of cellulase used in this invention is 5-20 mg / g of solid residue; the cellulase is preferably Novozymes CTec 3. The enzymatic hydrolysis time in this invention is 46-50 h; the enzymatic hydrolysis temperature is 45-55 °C. After enzymatic hydrolysis, solid-liquid separation is performed to obtain a lignin-rich filter residue and a filtrate rich in fermentable sugars.

[0035] In this invention, the filtrate rich in fermentable sugars is inoculated with Saccharomyces cerevisiae for ethanol fermentation. The Saccharomyces cerevisiae is Saccharomyces cerevisiae ATCC 26603.

[0036] In this invention, the lignin-rich filter residue is mixed with a sodium hydroxide solution, and after treatment, solid-liquid separation is performed to obtain a lignin solution. The lignin solution is then passivated with pyrite, and after the reaction, solid-liquid separation is performed, followed by freeze-drying to obtain passivated pyrite.

[0037] The concentration of the sodium hydroxide solution in this invention is 0.05–0.5 mol / L; the solid content of the filter residue after mixing with the sodium hydroxide solution is 5–15%. The temperature for treating the filter residue and sodium hydroxide solution after mixing is 115–125°C, and the time is 55–65 min.

[0038] In this invention, pyrite accounts for 1-2% of the lignin solution mass. This invention utilizes lignin extracted from lignocellulosic biomass waste to passivate pyrite, controlling AMD formation at its source. Lignin acts as a passivating agent, forming a passivation film on the pyrite surface, thereby reducing or preventing the erosion of metal minerals by oxygen or other oxidants, and decreasing AMD formation. The passivation treatment temperature is 25-30℃, and the passivation time is 230-250 min. After the passivation reaction, solid and liquid are separated, and the resulting solid residue is freeze-dried to obtain passivated pyrite.

[0039] In this invention, passivated pyrite is preferably added to a hydrochloric acid solution with pH=1 to conduct an acid leaching experiment to verify the passivation efficiency of pyrite. The amount of passivated pyrite added is 0.6g / 100ml hydrochloric acid solution.

[0040] Figure 1 This is a schematic diagram illustrating the treatment process of coupled waste biological straw and acidic mine wastewater in certain embodiments of the present invention. Figure 1It is known that: lignocellulose biomass and AMD are mixed and pretreated at 90-120℃ for 1-4 hours, followed by solid-liquid separation to obtain filtrate and filter residue. The filtrate is then used for SRB bioremediation. The filter residue is enzymatically hydrolyzed with cellulase at 55℃ for 48 hours, and the product is then separated into solid and liquid components to obtain filtrate and filter residue again. The filtrate is then used for ethanol fermentation. The obtained filter residue is mixed with 0.2 mol / L NaOH solution and treated at 120℃ for 1 hour, followed by solid-liquid separation to obtain lignin extract. The lignin extract is then passivated with pyrite to obtain passivated pyrite.

[0041] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, of a method for simultaneous source and end-of-pipe treatment of acidic mine wastewater provided by the present invention, should not be construed as limiting the scope of protection of the present invention.

[0042] Example 1

[0043] This embodiment follows the steps of refining lignocellulose biomass ethanol and AMD treatment:

[0044] Step 1: Mix corn cobs with AMD at a corn cob addition rate of 10% and treat at 120°C for 1 hour. After treatment, perform solid-liquid separation to obtain a solid residue rich in cellulose and lignin and a filtrate rich in hemicellulose.

[0045] Step two: After washing the solid residue from step one to neutral pH, buffer solution and Novozymes CTec3 cellulase were added to bring the solid content of the mixture to 10%. Enzymatic hydrolysis was carried out for 48 hours. The amount of cellulase used was 20 mg / g of solid residue; the buffer solution was 0.05 M acetate buffer with a pH of 5.5; and the hydrolysis temperature was 50℃. After solid-liquid separation, a lignin-rich filter residue and a filtrate rich in fermentable sugars were obtained. The filtrate was inoculated with Saccharomyces cerevisiae ATCC 26603 for ethanol fermentation. In this step, the concentration of fermentable sugars in the filtrate was 30 g / L, and the ethanol yield was 15 g / L, which is 93.2% of the theoretical yield.

[0046] Step 3: The filtrate rich in hemicellulose from Step 1 was inoculated with sulfate-reducing bacteria (inoculation amount of 30%) for anaerobic culture to reduce and remove sulfate and heavy metals in AMD. The sulfate removal rate was 97.2%, and the removal rates of major heavy metals (Mn, Cd, Co, Pb, Ni, Cu) all exceeded 60%, with Cd having the highest removal rate of 88.8%.

[0047] Step four: Mix the filter residue from step two with a 0.2M sodium hydroxide solution, with a solid content of 10%, and treat at 120℃ for 1 hour. Separate the solid and liquid components; the filtrate is the lignin solution. Add pyrite to the lignin solution for passivation treatment for 4 hours, with a pyrite content of 1%. After the reaction, separate the solid and liquid components, and freeze-dry the solid residue to obtain passivated pyrite. Acid leaching experiments were conducted by adding the passivated pyrite to a hydrochloric acid solution at pH=1, with the amount of passivated pyrite added being 0.6 g / 100 ml of hydrochloric acid solution. The results showed that, based on the total amount of iron released, the passivation efficiency of lignin on pyrite reached 74.4%, while based on the amount of SO4 released... 2- The passivation efficiency of lignin on pyrite was calculated to be 74.6%.

[0048] Example 2:

[0049] This embodiment follows the steps of refining lignocellulose biomass ethanol and AMD treatment:

[0050] Step 1: Mix corn cobs with AMD at a corn cob addition rate of 15% and treat at 90°C for 4 hours. After treatment, perform solid-liquid separation to obtain a solid residue rich in cellulose and lignin and a filtrate rich in hemicellulose.

[0051] Step two: After washing the solid residue from step one to neutral pH, buffer solution and cellulase were added to make the solid content of the mixture 10%, and enzymatic hydrolysis was performed for 48 hours. The amount of cellulase used was 5 mg / g of solid residue; the buffer solution was 0.05 M acetate buffer with a pH of 5.5; and the hydrolysis temperature was 45℃. After solid-liquid separation, a lignin-rich filter residue and a filtrate rich in fermentable sugars were obtained. The filtrate was inoculated with *Saccharomyces cerevisiae* ATCC 26603 for ethanol fermentation. In this step, the concentration of fermentable sugars in the filtrate was 28 g / L, and the ethanol yield was 14 g / L, which was 93.2% of the theoretical yield.

[0052] Step 3: The filtrate rich in hemicellulose from Step 1 was inoculated with sulfate-reducing bacteria (inoculation amount of 20%) for anaerobic culture to reduce and remove sulfate and heavy metals in AMD. The sulfate removal rate was 96.8%, and the removal rates of major heavy metals (Mn, Cd, Co, Pb, Ni, Cu) all exceeded 60%, with Cd having the highest removal rate of 86.7%.

[0053] Step four: Mix the filter residue from step two with a 0.05M sodium hydroxide solution, with a solid content of 5%, and treat at 120℃ for 1 hour. Separate the solid and liquid components; the filtrate is the lignin solution. Add pyrite to the lignin solution for passivation treatment for 4 hours, with a pyrite content of 1%. After the reaction, separate the solid and liquid components, and freeze-dry the solid residue to obtain passivated pyrite. Acid leaching experiments were conducted by adding the passivated pyrite to a hydrochloric acid solution at pH=1, with the amount of passivated pyrite added being 0.6 g / 100 ml of hydrochloric acid solution. The results showed that, based on the total amount of iron released, the passivation efficiency of lignin on pyrite reached 71.8%, while based on the amount of SO4 released... 2- The passivation efficiency of lignin on pyrite was calculated to be 72.1%.

[0054] Example 3:

[0055] This embodiment follows the steps of refining lignocellulose biomass ethanol and AMD treatment:

[0056] Step 1: Mix corn cobs with AMD, with the corn cob addition amount being 20%, and treat at 110℃ for 2 hours. After treatment, the resulting slurry is subjected to solid-liquid separation to obtain a solid residue rich in cellulose and lignin and a filtrate rich in hemicellulose.

[0057] Step two: After washing the solid residue from step one to neutral pH, buffer solution and cellulase were added to make the solid content of the mixture 15%, and enzymatic hydrolysis was performed for 48 hours. The amount of cellulase used was 15 mg / g of solid residue; the buffer solution was 0.05 M acetate buffer with a pH of 5.5; and the hydrolysis temperature was 55℃. After solid-liquid separation, a lignin-rich filter residue and a filtrate rich in fermentable sugars were obtained. The filtrate was inoculated with *Saccharomyces cerevisiae* ATCC 26603 for ethanol fermentation. In this step, the concentration of fermentable sugars in the filtrate was 35 g / L, and the ethanol yield was 17 g / L, which is 95.1% of the theoretical yield.

[0058] Step 3: The filtrate rich in hemicellulose from Step 1 was inoculated with sulfate-reducing bacteria (inoculation amount of 40%) for anaerobic culture to reduce and remove sulfate and heavy metals in AMD. The sulfate removal rate was 97.6%, and the removal rates of major heavy metals (Mn, Cd, Co, Pb, Ni, Cu) all exceeded 60%, with Cd having the highest removal rate of 83.2%.

[0059] Step four: Mix the filter residue from step two with a 0.5M sodium hydroxide solution, with a solid content of 15%, and treat at 120℃ for 1 hour. Separate the solid and liquid components; the filtrate is the lignin solution. Add pyrite to the lignin solution for passivation treatment for 4 hours, with a pyrite content of 2%. After the reaction, separate the solid and liquid components; freeze-dry the solid residue to obtain passivated pyrite. Acid leaching experiments were conducted by adding the passivated pyrite to a hydrochloric acid solution with pH=1, with an addition amount of 0.6 g / 100 ml hydrochloric acid solution. The results showed that, based on the total iron released, the passivation efficiency of lignin on pyrite reached 72.3%, while based on the released SO4... 2- The passivation efficiency of lignin on pyrite is calculated to be 73.3%.

[0060] As can be seen from the above embodiments, the present invention provides a method for simultaneous source and end-of-pipe treatment of ethanol biorefining and acidic mine wastewater, comprising the following steps: 1) mixing lignocellulose biomass and acidic mine wastewater, and performing solid-liquid separation on the treated slurry to obtain a solid residue rich in cellulose and lignin and a filtrate rich in hemicellulose; 2) washing the solid residue rich in cellulose and lignin from step 1) to neutrality with water, adding buffer solution and cellulase, performing enzymatic hydrolysis, and then performing solid-liquid separation to obtain filter residue and a filtrate rich in fermentable sugars; inoculating the filtrate rich in fermentable sugars with brewer's yeast for ethanol fermentation; 3) mixing the filter residue from step 2) with sodium hydroxide solution, treating and then performing solid-liquid separation to obtain a lignin solution; passivating the lignin solution with pyrite, reacting and then performing solid-liquid separation, and freeze-drying to obtain passivated pyrite. This invention utilizes regenerable lignocellulosic biomass from pretreated acidic mine wastewater as raw material to produce bioethanol, achieving green recycling of resources and low-cost management of AMD (Alternative Dioxide). The invention uses cellulose from lignocellulosic biomass for ethanol production, and the hemicellulose remaining in the AMD after pretreatment serves as a carbon source for SRB (sulfate-reducing sulfide minerals), achieving sulfate reduction and heavy metal removal in AMD. Simultaneously, waste lignin is used to passivate sulfide ores, achieving simultaneous source and end-of-pipe treatment of AMD. This invention achieves full utilization of lignocellulosic biomass components, improves the utilization rate of lignocellulosic biomass, reduces waste generation, provides a new approach to AMD management, and lowers the cost of ethanol refineries. Experimental results show that the passivation efficiency of lignin on pyrite is 71.8–74.4% (based on the released SO42-). 2- (Calculation); The theoretical yield of ethanol is 93.2%–95.1%; The removal rate of Cd in AMD is 83.2%–88.8%.

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for simultaneously treating the source and end of acid mine wastewater from ethanol biorefining, comprising the following steps: 1) Mix lignocellulose biomass and acidic mine wastewater, and perform solid-liquid separation on the treated slurry to obtain solid residue rich in cellulose and lignin and filtrate rich in hemicellulose; In step 1), the filtrate rich in hemicellulose is inoculated with sulfate-reducing bacteria at an inoculation rate of 20% to 40%, and then subjected to anaerobic culture. 2) After washing the cellulose- and lignin-rich solid residue from step 1) to neutral, add buffer solution and cellulase, perform enzymatic hydrolysis, and then separate the solid and liquid to obtain filter residue and filtrate rich in fermentable sugars; inoculate the filtrate rich in fermentable sugars with brewer's yeast for ethanol fermentation; the amount of cellulase used is 5~20 mg / g solid residue; 3) Mix the filter residue from step 2) with sodium hydroxide solution, treat and then separate the solid and liquid to obtain a lignin solution; passivate the lignin solution with pyrite, react and then separate the solid and liquid, freeze-dry to obtain passivated pyrite; The pyrite content is 1% to 2% of the lignin solution mass; the passivation treatment temperature is 25 to 30°C, and the passivation treatment time is 230 to 250 min.

2. The method according to claim 1, characterized in that, The treatment in step 1) is carried out at a temperature of 90~120℃ for 1~4 hours.

3. The method according to claim 1, characterized in that, The enzymatic hydrolysis time in step 2) is 46-50 hours; the enzymatic hydrolysis temperature is 45-55°C.

4. The method according to claim 1, characterized in that, The solid content of the mixture after adding the buffer solution in step 2) is 10%~15%.

5. The method according to claim 1, characterized in that, In step 3), the concentration of the sodium hydroxide solution is 0.05~0.5 mol / L; the solid content of the filter residue after mixing with the sodium hydroxide solution is 5%~15%. The buffer solution is an acetate or citrate buffer; the pH of the buffer solution is 5.0~5.

5.

6. The method according to claim 1, characterized in that, In step 3), the temperature for the post-treatment of the filter residue and sodium hydroxide solution is 115~125℃, and the time is 55~65min.

7. The method according to claim 1, characterized in that, The lignocellulose biomass is selected from one or more of corn cobs, corn stalks, wheat stalks, rice stalks, rapeseed stalks, and sugarcane bagasse; The lignocellulose biomass accounts for 10% to 20% of the mass of the acidic mine wastewater.

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