A method for producing mercury remediation materials using sulfate ions from acidic mine wastewater.

Abstract

This application discloses a method for producing mercury remediation materials using sulfate ions from acidic mine wastewater, comprising the following steps: S1, adding straw and concentrated SO4 into the reactor. 2‑ The solution undergoes anaerobic fermentation; S2, acidic mine wastewater is mixed with carbonate rock powder slurry to adjust the pH and then divided into two parts. One part of the wastewater is mixed with the biogas slurry produced by fermentation and introduced into an anaerobic pond for desulfurization of the mine wastewater; the effluent from the anaerobic pond is mixed with the other part of the mine wastewater and then enters an aerobic aeration pond for aeration and carbonate rock powder slurry is added. NaOH or Ca(OH)2 is added in the middle of the aeration pond. The effluent is led out to a sedimentation pond for sedimentation and separation. The supernatant then enters a filter pond and wetland ecosystem to obtain effluent that can be discharged or reused. The sludge from the sedimentation pond is recycled or discharged; S3, concentrated SO4 is obtained from the effluent. 2‑ The solution is introduced into the reactor. This removes SO4 from the acidic mine wastewater. 2‑ The mercury remediation material is formed on straw, reducing SO4 levels. 2‑ Concentration, to achieve resource utilization of pollutants.

Description

Technical Field

[0001] This invention relates to the field of acidic mine wastewater treatment, and specifically to a method for producing mercury remediation materials using sulfate ions from acidic mine wastewater. Background Technology

[0002] Acidic mine wastewater typically has a low pH and is rich in Fe. 2+ Mn 2+ SO4 2- Substances such as Fe. Existing remediation projects mainly use Fe. 2 + Mn 2+ The focus of related work is on the removal of metal ions and the increase of pH, but untreated SO4-containing substances... 2- Direct discharge of wastewater into natural water bodies can easily lead to water quality deterioration, affecting the growth and survival of aquatic organisms; wastewater containing SO4... 2- Wastewater seeping into the soil can alter its pH level, affecting plant growth and the survival of soil microorganisms. Furthermore, plants absorb SO4 from the soil. 2- Afterwards, it may lead to reduced crop yields and pose potential harm to human health; long-term intake of substances containing excessive SO4... 2- Foods that may cause SO4 in the human body 2- The accumulation of SO4 can have adverse effects on the human kidneys, cardiovascular system, and other systems. 2- Excessive levels of SO4 can lead to ecosystem imbalances, affecting the structure and diversity of plant and animal populations, and damaging the stability and resilience of ecosystems. 2- The concentration limits for this substance have been set in relevant drinking water standards.

[0003] SO4 in the environment 2- S 2- Sulfur-containing organic compounds affect the speciation and bioavailability of heavy metals: such as sulfur (S). 2- With Hg 2+ Sulfur-containing substances can form HgS precipitates and mineralize mercury, reducing its bioavailability; while sulfur-containing functional groups such as thiol groups can form strong and stable complexes with mercury, enhancing the adsorption of mercury by the carrier. Therefore, sulfur-containing substances are often used as modifiers for heavy metal passivation materials to increase their binding capacity for heavy metals.

[0004] Acidic mine wastewater contains a large amount of SO4 2- Carbonate rocks are a type of mineral widely found in karst regions such as Guizhou, and are inexpensive and readily available. In the process of treating wastewater using calcium-containing materials such as carbonate rocks, these minerals can react with H+ in the water. + The reaction produces Ca. 2+ CO2 and H2O cause a large amount of Ca to be released. 2+Soluble in water, because CaSO4 is a slightly soluble substance, in Ca 2+ When CaSO4 is produced in large quantities, it can easily form a large amount of solid coatings on the pool walls, pipe walls, reaction medium surfaces, and equipment, which greatly affects the stable and efficient operation of acidic mine wastewater treatment systems. Avoiding or reducing the production of CaSO4 is of great significance for reducing the treatment costs of acidic mine wastewater and improving stable operating efficiency.

[0005] Agricultural production processes leave a large number of plant root residues in the soil. These residues promote the transformation of insoluble HgS in the soil into organically bound HgS. On the other hand, these residues are more easily utilized as a carbon source by mercury methylating microorganisms, increasing the abundance or activity of mercury methylating microorganisms. Both of these results promote the transformation of mercury into more toxic methylmercury and its accumulation in crops. This phenomenon is more pronounced in high-mercury soils.

[0006] Referring to existing technology, a straw fermentation method and straw return method suitable for mercury-contaminated soil - CN116162004 B, utilizes anaerobic fermentation of straw in a fermentation device containing additives to obtain fermentation products, wherein the additives are selected from one or more of soluble sulfates, metal sulfides, iron ore, and maifanite (i.e., providing SO4). 2- The additives used in this method are mainly derived from various chemicals, with sulfates being the most prevalent. If the acidic mine wastewater is rich in SO4... 2- As a raw material for making mercury remediation materials, it can reduce SO4 in acidic mine wastewater. 2- This can reduce the impact of acid mine wastewater discharge on the water environment, soil environment, and human beings; it can also effectively improve the operating efficiency of acid mine wastewater treatment systems; and finally, it can realize the resource utilization of pollutants and turn waste into treasure. Summary of the Invention

[0007] This invention aims to provide a method for producing mercury remediation materials using sulfate ions in acidic mine wastewater, specifically by utilizing the SO4 ions abundant in the mine wastewater. 2- The pollutants are removed and transformed into sulfur-containing organic compounds, which are then loaded onto straw for utilization. This reduces the impact on the water environment, soil environment, and human beings, while realizing the resource utilization of pollutants and turning waste into treasure.

[0008] A method for producing mercury remediation materials using sulfate ions from acidic mine wastewater includes: S1, adding straw and concentrated SO4 into a reactor. 2-The solution undergoes anaerobic fermentation; S2, acidic mine wastewater is mixed with carbonate rock powder slurry to adjust the pH and then divided into two parts. One part of the wastewater is mixed with the biogas slurry produced by fermentation and introduced into an anaerobic pond for desulfurization of the mine wastewater; the effluent from the anaerobic pond is mixed with the other part of the mine wastewater and then enters an aerobic aeration pond for aeration and carbonate rock powder slurry is added. NaOH or Ca(OH)2 is added in the middle of the aeration pond and then led to a sedimentation pond for sedimentation and separation. The supernatant then enters a filter pond and wetland ecosystem to obtain effluent that can be discharged or reused. The sludge from the sedimentation pond is recycled or discharged; S3, concentrated SO4 is obtained from the effluent. 2- The solution is then introduced into the reactor.

[0009] This plan will concentrate SO4 from acidic mine wastewater. 2- Co-fermentation with straw produces SO4 2- It is converted into sulfur-containing ligand organic matter and loaded onto straw to form mercury remediation materials.

[0010] Working principle of the invention:

[0011] After acidic mine wastewater flows out of the mine shaft or effluent point, a certain amount of carbonate rock powder slurry is added to raise the pH of the wastewater. The wastewater is then divided into two parts. One part is led to an anaerobic digester, during which oxygen should be avoided to ensure the pH of the acidic mine wastewater reaches above 5.5 before entering the anaerobic digester. The wastewater entering the anaerobic digester is mixed with the biogas slurry drawn from the reactor. Through the action of sulfate-reducing bacteria and other microorganisms, the SO42- in the acidic mine wastewater is reduced. 2- The gas is reduced to H2S and discharged from the aqueous phase, thus lowering the SO4 content in the water. 2- The content; or converted into S 2- It forms insoluble sulfides with heavy metals in wastewater, and the biogas slurry can also provide a certain amount of organic matter for the growth of microorganisms in the anaerobic pond. The amount of biogas slurry added is sufficient to remove SO4. 2- The target is to minimize the amount added, thereby reducing the difficulty of COD treatment in subsequent systems. Another portion of the mine wastewater, after pH adjustment, is mixed with the effluent from the anaerobic tank and then enters the subsequent aeration tank for further treatment. Because a portion of the mine wastewater is used for anaerobic reaction, the higher COD concentration can increase SO4 levels. 2- The removal efficiency is improved, and the mixture is then mixed with the mine wastewater that has not undergone anaerobic reaction, which effectively reduces the COD content in the subsequent wastewater and reduces the difficulty of COD removal.

[0012] Fe 2+ / 3+ A large amount of H is produced during the hydrolysis process. + To maintain the pH of the wastewater at neutral, it consumes a large amount of carbonate rock, which in turn increases the calcium content in the water. 2+ The concentration increased significantly in SO4 2-At high concentrations, it causes calcium in the water to rise. 2+ and SO4 2- When the concentration product exceeds its ion product, a large amount of CaSO4 solid is generated, and a large amount of crystals are formed on the surface of carbonate rock particles, pool walls, pipe walls, and equipment inner walls, which in turn damages the stability of system operation and increases the difficulty of operation and maintenance management.

[0013] Therefore, appropriately introducing biogas slurry from the reactor into the anaerobic digester can remove some of the SO4 carried in by the partially acidic mine wastewater from the anaerobic digester. 2- To perform reduction, ensure that the Ca in each reaction stage is adequate. 2+ and SO4 2- The concentration product is lower than the ion product, thus reducing the frequency of scaling in various areas of the system. During this process, it is also necessary to avoid excessive introduction of biogas slurry, otherwise it will lead to high COD effluent from the anaerobic tank, increasing the difficulty of COD treatment in the system and resulting in waste.

[0014] The mine wastewater flowing out of the anaerobic pond is mixed with the pH-adjusted mine wastewater and then enters the aerobic aeration tank. The aeration tank is equipped with packing material that facilitates microbial attachment and growth. Aeration is performed, and carbonate rock powder slurry is added. The aeration process utilizes Fe... 2+ Oxidized to Fe 3+ Then utilize carbonate rocks and Fe 3+ H is formed during hydrolysis + Neutralization is carried out to neutralize the Fe in the water. 2+ / 3+ Fe(OH)3 solid is formed. During this process, microorganisms promote the reaction and simultaneously biologically treat the COD in the water, achieving COD removal. NaOH is added in the middle section of the aeration tank to raise the wastewater pH to above 10.5, utilizing Mn... 2+ Other heavy metal ions may have a concentration below 10 when the pH is above 10.3. -5 The mol / L characteristic enables the basic removal of heavy metal ions from water. After pH enhancement and metal ion conversion to solids are completed in the aeration tank, sedimentation separation is carried out in the sedimentation tank, allowing solid matter in the wastewater to be separated from the water by sedimentation. The supernatant enters the filter tank, and the wastewater after filtration enters the wetland system. The wetland ecosystem continuously treats the residual pollutants such as COD in the wastewater before discharge.

[0015] Because the wetland effluent contains a certain concentration of SO4 2- The wetland effluent can be introduced into an SO42-containing solution containing strong anion exchange resin as needed. 2- Concentration systems or membrane separation systems utilize anion exchange resins to adsorb SO4 from water. 2- The treated water is discharged externally. After the resin becomes saturated, it is regenerated using NaCl. The waste liquid after regeneration contains a large amount of SO4. 2-(The concentrate in the membrane separation system is rich in SO4) 2- Clear liquid SO4 2- (With a low content), it is a raw material for making mercury remediation materials. Sulfate ions are introduced into the reactor at the concentration used for sulfate, and co-fermented with straw to produce mercury remediation materials loaded with sulfur-containing ligand organic matter. This mercury remediation material is used in farmland contaminated with mercury and other heavy metals to inhibit the release of mercury and other heavy metal ions from the farmland, reduce environmental pollution from straw waste, beautify the regional environment, and realize the effective utilization of waste by turning it into a valuable resource.

[0016] The present invention has the following technical effects:

[0017] 1. SO4 produced from treated wastewater 2- SO4 contained in the concentrate 2- Based on the principle that organic matter such as straw can generate sulfur-loaded organic compounds under anaerobic conditions, mercury remediation materials are prepared. This optimizes the treatment process of acidic mine wastewater while simultaneously realizing the extraction of sulfur-containing organic compounds from straw and SO4. 2- Resource utilization and turning waste into treasure;

[0018] 2. Utilizing anion exchange resins to remove SO4 from acidic mine wastewater 2- Concentration is carried out to reduce SO4 in the tailings of mine wastewater treatment. 2- The content increases the SO4 content in the solution reacting with straw. 2- Concentration (or SO4 using membrane separation) 2- (Concentration) reduces the amount of liquid entering the reactor, thereby reducing the amount of sulfate and the amount of effluent from the reactor, reducing the amount of wastewater entering the mine water treatment system, and reducing the system's treatment load.

[0019] 3. The effluent from the reactor can provide the organic matter needed by sulfur-reducing bacteria, and under anaerobic conditions, it helps to reduce SO4 levels. 2- Restore to S 2- Reduce SO4 in wastewater 2- The content of [certain substances] reduces the subsequent formation of CaSO4, thereby reducing the formation of large amounts of crystallized inclusions on the surface of carbonate rock particles, pool walls, pipe walls, and equipment inner walls.

[0020] 4. After adding carbonate rock powder slurry to the aerobic aeration tank for neutralization reaction, a small amount of NaOH is added to increase the pH of the wastewater to above 10.3. This can achieve the basic removal of heavy metal ions in the water, ensuring that there is no significant increase in metal ions in the subsequent reactors, and avoiding the introduction of new metal ions into the soil environment during the use of mercury remediation materials.

[0021] Preferably, after the acidic mine wastewater flows out of the mine shaft or outflow point, a certain amount of carbonate rock powder slurry is added to raise the pH of the acidic mine wastewater to above 5.5, so as to ensure that the sulfate-reducing bacteria in the subsequent anaerobic tank can grow normally.

[0022] Preferably, the biogas slurry produced by the reactor is introduced into the anaerobic tank, and the wastewater retention time in the anaerobic tank should be greater than one day. The tank is filled with packing material that facilitates microbial attachment. The amount of biogas slurry added should meet the SO42- requirements. 2- Partial removal is possible, ensuring the remaining SO4 2- and Ca 2+ The concentration product in the treatment system is always less than the solubility product. The amount of COD carried in by the biogas slurry should be sufficient to ensure SO4 removal. 2- Reduce the amount added based on the required amount to reduce the difficulty of COD processing in subsequent systems.

[0023] Preferably, a two-stage dosing method is used in the aerobic aeration tank. The first stage uses inexpensive carbonate rock powder slurry as a neutralization medium to neutralize H+ ions generated during pollutant removal, maintaining the pH between 6.5 and 7.0. The second stage adds NaOH or Ca(OH)2 primarily to raise the pH to above 10.5, meeting the requirements for manganese and other heavy metal removal and ensuring that subsequent mercury remediation materials are no longer rich in potentially harmful heavy metal ions. This two-stage dosing method significantly reduces the amount of expensive NaOH or Ca(OH)2 used, lowering system treatment costs.

[0024] Preferably, the wetland effluent is introduced into a concentration system, which can employ membrane treatment or ion exchange resin desalination technology to remove SO4. 2- Concentrated, containing SO4 2- The treated water is either discharged as effluent or reused.

[0025] Preferably, it will be rich in SO4 2- The concentrated liquid, after being adjusted to a certain concentration, is fed into the reactor and reacted with straw inside the reactor using anaerobic microorganisms to generate SO42-. 2- It is converted into sulfur-containing ligand organic matter and attached to the straw to complete the production of mercury remediation materials.

[0026] Preferably, when removing straw from the reactor, all the straw in the reactor should not be removed at once. Instead, some straw can be removed from the reactor and new straw added immediately; or all straw can be removed, some can be taken out, and the remaining straw can be mixed with new straw and then placed back into the reactor. The amount of straw removed and replenished each time should be 20% to 50% of the total straw volume. Attached Figure Description

[0027] Figure 1This is a flowchart illustrating a method for producing mercury remediation materials using sulfate ions from acidic mine wastewater, as described in this invention. Detailed Implementation

[0028] The following detailed description illustrates the specific implementation method:

[0029] Example: After acidic mine wastewater flows out of the mine shaft or effluent point, a certain amount of carbonate rock powder slurry is added. During this process, oxygen should be avoided from entering the wastewater to ensure the pH reaches above 5.5, and SO42- is added accordingly. 2- To address the issue of SO4 removal, a portion of the supernatant from the acidic mine wastewater is taken and sent to an anaerobic digester. The wastewater entering the anaerobic digester is mixed with biogas slurry introduced from the reactor. Through the action of sulfate-reducing bacteria and other microorganisms, the SO4 in the acidic mine wastewater is reduced. 2- The gas is reduced to H2S and discharged from the aqueous phase, thus lowering the SO4 content in the water. 2- The biogas slurry also provides a certain amount of organic matter for the growth of microorganisms in the anaerobic digester. The amount of acidic mine wastewater entering the anaerobic digester is controlled to ensure the Ca content in each treatment unit. 2+ With the concentration product of SO42- and SO42- at maximum concentration being less than the solubility product, excess SO42- is removed through an anaerobic reactor. 2- The COD should be removed, and the amount of COD in the effluent from the anaerobic tank should be reduced as much as possible.

[0030] After the mine wastewater flowing out of the anaerobic pond is mixed with the mine wastewater that has not yet entered the anaerobic pond, it enters the aerobic aeration tank. The aerobic aeration tank is equipped with packing material that facilitates the attachment and growth of microorganisms. Aeration is performed, and carbonate rock powder slurry is added. The aeration process is used to remove Fe... 2+ Oxidized to Fe 3+ Then utilize carbonate rocks and Fe 3+ H is formed during hydrolysis + Neutralization is carried out to neutralize the Fe in the water. 2+ / 3+ The formation of Fe(OH)3 solid occurs, and in this process, microorganisms can promote the formation of Fe. 2+ To Fe 3+ The oxidation process involves adding NaOH (or Ca(OH)2) to the middle section of the aeration tank to raise the pH of the wastewater to above 10.5, utilizing Mn... 2+ Other heavy metal ions may have a concentration below 10 when the pH is above 10.3. -5 The mol / L characteristic enables the basic removal of heavy metal ions from water. After metal ion removal is completed in the aeration tank, the wastewater enters the sedimentation tank for mud-water separation. The solid matter in the wastewater is separated from the water by sedimentation. The supernatant enters the filter tank, and the wastewater after filtration enters the wetland system. The wetland ecosystem continuously treats the residual pollutants such as COD in the wastewater before discharge.

[0031] Because the wetland effluent still contains a certain concentration of SO4 2- As needed, a portion of the wetland effluent can be introduced into an SO42-containing solution containing anion exchange resin. 2- The concentration system utilizes anion exchange resin to adsorb SO4 from water. 2- The treated water is either discharged or reused. Once the resin is saturated, it is regenerated using NaCl. The regenerated wastewater contains a large amount of SO4. 2- It is a raw material for making mercury remediation materials, according to SO4 2- SO4 was introduced using a concentration (referring to an existing method for straw fermentation and straw return to the field suitable for mercury-contaminated soil). 2- The material is co-fermented with straw in a reactor to produce mercury remediation material. This material is then applied to farmland contaminated with mercury and other heavy metals to inhibit the release of mercury and other heavy metal ions, reduce environmental pollution from straw waste, beautify the regional environment, and effectively utilize waste resources.

[0032] The specific technical principles are as follows:

[0033] 1. Characteristics of raw water: The quality and quantity of acidic mine wastewater are prone to change with the seasons and rainfall. The main discharge indicators involved in acidic mine wastewater are pH and Fe. 2+ Mn 2+ etc., SO4 2- It is not among the pollutants of key concern in wastewater discharge standards; however, when drinking water sources are involved, SO4 in the water... 2- Concentration will be a key concern. Secondly, when using calcium-containing alkaline substances to treat acidic wastewater, CaSO4 crystals are easily formed, causing scaling on pipe walls, vessel walls, and the surface of the reaction medium, which is not conducive to the stable operation of the treatment system.

[0034] Ca 2+ +SO4 2- →CaSO4↓

[0035] 2. Formation of sulfides: Contains SO4 2- During the anaerobic treatment of wastewater, on the one hand, sulfate-reducing bacteria (SRB) will reduce SO42-. 2- and SO3 2- Utilizing it as an electron acceptor, SO4 2- and SO3 2- Restored to H2S or S 2- On the other hand, under the action of microorganisms, some SO4 2- It will be converted into sulfur-containing organic matter, and the straw will form abundant pores during the decomposition process, so that the sulfur-containing organic matter will be loaded in the biogas residue of fermented straw.

[0036] 3. Anaerobic Removal Process for Pollutants: The reactivity of H2S with metal ions depends on the type of metal ions and the conditions. Under certain conditions, H2S can react with Cu... 2+ Co 2+ Zn 2+ Mn 2+ Ag + Cu + Hg 2+ Pb 2+ (In the absence of strong oxidizing substances in the system, M will be used as a reference below) n+ (representing metal ions) and S 2- The reaction directly produces an insoluble precipitate. These metal ions react with H₂S to form corresponding sulfide precipitates; however, H₂S reacts with Ca... 2+ Na + Mg 2+ Al 3+ Under normal circumstances, they do not react. Whether the products of these reactions form a precipitate depends on the solubility of the product and the pH of the reaction environment. Creating a suitable environment for H2S and M... n+ The reaction conditions facilitate the formation of MS precipitate.

[0037] Mn 2+ +H₂S→MnS+2H +

[0038] Other metal parts (M) n+ ):M n+ +H2S→MS (n / 2) +nH +

[0039] 4. Aerobic removal process of pollutants

[0040] After the initial anaerobic reaction process, a small amount of Fe remains in the water. 2+ Al 3+ Heavy metal ions, such as Fe, can be oxidized. 2+ Oxidizable ions are used for oxidation, and under low pH conditions, carbonate rock slurry can remove a large amount of pollutants. After raising the pH to 10.3, the remaining heavy metal ions can be basically removed. The oxidation and precipitation removal principle (Fe as an example) is as follows:

[0041] 2Fe 2+ +2H + +0.5O2→2Fe 3+ +H2O oxidation process

[0042] Fe 3+ +2H₂O→Fe(OH)₃↓+3H + Hydrolysis and precipitation process

[0043] 2Fe 2+ +3H₂O + 0.5O₂ → 2Fe(OH)₃↓ + 4H + Overall reaction formula

[0044] Mn 2+ +2OH - +0.5O2→MnO2↓+H2O

[0045] The wastewater treatment process at each stage was tested, and the following data were obtained:

[0046] Table 1 - Reactors

[0047] <]]> COD (mg / L) Water ingress 6120 18 Out of water 560 8608

[0048] Table 1 shows that the reactor can efficiently remove SO4 through the fermentation process. 2- The decrease of over 90% indicates that straw fermentation has a significant impact on SO4 levels. 2- It exhibits significant adsorption and conversion effects.

[0049] Table 2 - Anaerobic Tanks

[0050]

[0051]

[0052] Table 2 shows:

[0053] When the ratio of mine water to biogas slurry is 3:1, SO4 2- The SO42 concentration decreased from (2338×3+560×1) / 4=1833mg / L to 606mg / L, achieving a removal rate of 67%; when the ratio was increased to 4:1, SO422... 2- It only decreased to 794 mg / L, with a removal rate of 57%.

[0054] This indicates that insufficient biogas slurry addition will lead to SO4. 2- Insufficient reduction can be controlled by increasing the proportion of biogas slurry or increasing the COD concentration during the reaction process. However, this will increase the COD concentration in the anaerobic pond effluent, making subsequent treatment more difficult. For example, in the experiment, the effect of a 3:1 volume ratio of mine water to biogas slurry was better than that of 4:1, but the COD concentration in the anaerobic pond effluent increased. Therefore, an appropriate volume ratio should be found during the implementation process to ensure the carbon source and sulfur-reducing bacteria activity of anaerobic microorganisms and reduce the difficulty of subsequent COD treatment.

[0055] SO4 2- The reduction effect is related to the mixing ratio:

[0056] When the ratio of mine water to biogas slurry is 3:1, SO4 2-The concentration of the mixed influent decreased from (2338×3+560×1) / 4=1833mg / L to 606mg / L, with a removal rate of 67%.

[0057] The effluent COD was significantly lower than that of the biogas slurry influent (873 / 720 vs. 8608), indicating that the microorganisms in the anaerobic digester provide energy by decomposing organic matter in the biogas slurry, while simultaneously reducing SO42-. 2- It is reduced to H2S, achieving a synergistic effect of "carbon source utilization - sulfur reduction".

[0058] During anaerobic processes, H2S release consumes H2S. + Meanwhile, the carbonate buffer system in the biogas slurry raises the pH from 6.0-6.3 to 6.8-6.9, creating conditions for subsequent aerobic treatment.

[0059] Table 3 - Mineral Water

[0060]

[0061] Table 3 shows:

[0062] High-efficiency removal of heavy metals:

[0063] Fe 2+ / Fe 3+ The concentration decreased from 122 mg / L to 0.1–0.2 mg / L, with a removal rate exceeding 99%, attributed to the oxidation of iron ions to Fe in the aerobic aeration tank. 3+ It also hydrolyzes to form Fe(OH)3 precipitate.

[0064] When the pH is increased to 10.5, Mn 2+ Heavy metal ions are removed by precipitation with hydroxides or oxides. The continuous oxidation process lowers the wastewater pH to below 9.0.

[0065] SO4 2- Removal mainly depends on the anaerobic stage:

[0066] SO4 after mixing 2- The decrease of only 15%-19% indicates that the aerobic stage contributes little to sulfate removal, with the main removal occurring in the anaerobic tank (through conversion to H2S by sulfur-reducing bacteria).

[0067] pH regulation plays a crucial role:

[0068] Adding carbonate rock powder slurry and NaOH (or Ca(OH)2) raises the pH from acidic (4.7) to slightly alkaline (around 10.5), promoting the precipitation of metal ions while preventing CaSO4 scaling (because SO4...). 2- (Partially removed during the anaerobic stage).

[0069] In summary, anaerobic digesters utilize biogas slurry to provide a carbon source and sulfur-reducing bacteria, with a primary focus on SO4 removal. 2- (Removal rate 57%-67%) and some COD. Aerobic tank: Almost completely removes Fe through oxidation-sedimentation. 2+ / 3+ Mn 2+ For heavy metals, pH adjustment is crucial. Wetlands + filtration further degrade COD and stabilize water quality, ensuring compliance with discharge standards.

[0070] Resource recycling: The high-COD biogas slurry from the reactor is directly used in the anaerobic digester, realizing the reuse of "waste carbon source"; the regenerated waste liquid after resin adsorption saturation contains a high concentration of SO4. 2- It is used to produce mercury remediation materials, inhibit the release of heavy metals such as mercury from farmland, and realize the transformation of "pollutants → functional materials".

[0071] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A method for producing mercury remediation materials using sulfate ions from acidic mine wastewater, characterized in that, Includes the following steps: S1. Add straw and concentrated SO4 into the reactor. 2- The solution undergoes anaerobic fermentation. S2. After adding carbonate rock powder slurry to adjust the pH of acidic mine wastewater, it is divided into two parts. One part of the wastewater is mixed with the biogas slurry produced by fermentation and introduced into the anaerobic pond for desulfurization of mine wastewater. The effluent from the anaerobic pond is mixed with the other part of the mine wastewater and enters the aerobic aeration pond for aeration and carbonate rock powder slurry is added. NaOH or Ca(OH)2 is added in the middle of the aeration pond and then led to the sedimentation pond for sedimentation and separation. The supernatant then enters the filter pond and wetland ecosystem to obtain effluent that can be discharged or reused. The sludge in the sedimentation pond is returned or discharged. S3. Obtain concentrated SO4 from the tailwater. 2- The solution is introduced into the reactor to produce mercury remediation materials.

2. The method for producing mercury remediation materials using sulfate ions from acidic mine wastewater according to claim 1, characterized in that, The S2 step raises the pH of the freshly discharged acidic mine wastewater to above 5.

5.

3. The method for producing mercury remediation materials using sulfate ions from acidic mine wastewater according to claim 2, characterized in that, S2 acidic mine wastewater shall be retained in the anaerobic tank for no less than 1 day. The anaerobic tank shall be filled with packing material and the mud and water shall be separated.

4. The method for producing mercury remediation materials using sulfate ions from acidic mine wastewater according to claim 3, characterized in that, The amount of water entering the anaerobic tank ensures that the SO4 content in the acidic mine wastewater is reduced in all units of the system. 2- and Ca 2+ The concentration product is less than the solubility product; the amount of COD carried in by the biogas slurry should meet the requirements for removing SO4. 2- Reduce the amount added based on the required amount.

5. The method for producing mercury remediation materials using sulfate ions from acidic mine wastewater according to claim 4, characterized in that, In the aerobic aeration tank, carbonate rock powder slurry is added at the beginning of the treatment process to maintain the pH of the acidic mining wastewater between 6.5 and 7.0; NaOH or Ca(OH)2 is added in the middle of the treatment process to raise the pH of the acidic mining wastewater to above 10.

5.

6. The method for producing mercury remediation materials using sulfate ions from acidic mine wastewater according to claim 5, characterized in that, Wetland effluent is introduced into a concentration system, which uses membrane treatment or ion exchange resin desalination technology to remove SO4. 2- Concentrated, containing SO4 2- The treated water is either discharged as effluent or reused.

7. The method for producing mercury remediation materials using sulfate ions from acidic mine wastewater according to claim 6, characterized in that, rich in SO4 2- The concentrated liquid, after being adjusted to a certain concentration, is fed into the reactor and reacted with straw inside the reactor using anaerobic microorganisms to generate SO42-. 2- It is converted into sulfur-containing ligand organic matter and attached to the straw to complete the production of mercury remediation materials.

8. The method for producing mercury remediation materials using sulfate ions from acidic mine wastewater according to any one of claims 1 to 7, characterized in that, Inside the reactor, the straw residence time is no less than 30 days, SO4 2- The solution should remain in the solution for at least 5 days, and a certain amount of nitrogen and phosphorus additives should be added as needed based on the growth of the microorganisms.

9. The method for producing mercury remediation materials using sulfate ions from acidic mine wastewater according to claim 8, characterized in that, Remove some straw from the reactor and then add new straw to the reactor.

10. The method for producing mercury remediation materials using sulfate ions from acidic mine wastewater according to claim 9, characterized in that, The amount of straw removed and replenished each time is 20% to 50% of the total amount of straw.

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