Method for producing mercury repair material by using sulfate radicals in acid mine wastewater

Abstract

The invention discloses a method for producing a mercury repair material by using sulfate radicals in acid mine wastewater. The method comprises the following steps: S1, adding straws and a concentrated SO4 < 2-> solution into a reactor for anaerobic fermentation; s2, adding carbonate rock powder slurry into the acid mine wastewater to adjust the pH value, dividing the acid mine wastewater into two parts, mixing one part of wastewater with biogas slurry generated by fermentation, and introducing the mixture into an anaerobic tank to desulfurize the mine wastewater; the effluent flowing out of the anaerobic tank is mixed with the other part of mine wastewater, the mixture enters an aerobic aeration tank for aeration, carbonatite powder slurry is added, NaOH or Ca (OH) 2 is added to the middle section of the aeration tank, the effluent is led out to a sedimentation tank for precipitation separation, supernate enters a filter tank and a wetland ecological system, and then tail water capable of being discharged or recycled is obtained. Sludge in the sedimentation tank is refluxed or discharged; and S3, obtaining a concentrated SO4 < 2-> solution from the tail water, and introducing the solution into the reactor. SO4 < 2-> in the acid mine wastewater is loaded on the straw to form a mercury repairing material, so that the concentration of SO4 < 2-> is reduced, and resource utilization of pollutants is realized.

Description

Technical Field

[0001] The present invention relates to the field of acid mine wastewater treatment, and in particular to a method for producing mercury repair materials by utilizing sulfate radicals in acid mine wastewater. Background Art

[0002] Acid mine drainage typically has a low pH and is rich in Fe 2+ 、Mn 2+ 、SO4 2- The existing treatment projects mainly use Fe 2 + 、Mn 2+ The relevant work is carried out with the focus on the removal of metal ions and the increase of pH, but the untreated SO4 2- Direct discharge of wastewater into natural waters can easily lead to water quality deterioration and affect the growth and survival of aquatic organisms; it contains SO4 2- The wastewater seeps into the soil, which changes the pH value of the soil and affects the growth of plants and the survival of soil microorganisms. In addition, plants absorb SO4 2- Afterwards, it may lead to reduced crop yields and potential harm to human health; long-term intake of excessively high SO4 2- Foods that may cause SO4 2- The accumulation of SO4 has adverse effects on the kidneys, cardiovascular system and other systems of the human body; 2- Too high a concentration will lead to an imbalance in the ecosystem, affect the structure and diversity of plant and animal populations, and undermine the stability and resilience of the ecosystem. 2- The concentration limits of these substances have been set in the relevant standards for drinking water.

[0003] SO4 in the environment 2- 、S 2- , Sulfur-containing organic matter affects the form and bioavailability of heavy metals: such as S 2- With Hg 2+ HgS can be precipitated and mineralized, reducing the bioavailability of mercury. Sulfur-containing functional groups, such as thiol, can form strong, stable complexes with mercury, enhancing the carrier's adsorption of mercury. Therefore, sulfur-containing substances are often used as modifiers for heavy metal passivation materials, increasing their ability to bind heavy metals.

[0004] Acid mine drainage contains a large amount of SO4 2- Since carbonate rock is a kind of mineral widely found in karst areas such as Guizhou, it has the characteristics of high quality and low price. In the process of using carbonate rock and other calcium-containing materials for wastewater treatment, carbonate rock minerals can react with H in water. + Reaction, generating Ca 2+ , CO2 and H2O, resulting in a large amount of Ca 2+Dissolved in water, since CaSO4 is a slightly soluble substance, 2+ After a large increase, a large amount of solid inclusions are easily formed on the pool wall, pipe wall, reaction medium surface and equipment, which greatly affects the stable and efficient operation of the acid mine drainage treatment system. Avoiding or reducing the generation of CaSO4 is of great significance to reducing the treatment cost of acid mine drainage and improving stable operation efficiency.

[0005] A large amount of plant roots remain in the soil during the agricultural production process. On the one hand, these roots promote the conversion of insoluble HgS in the soil into an organically bound state. On the other hand, these roots are more easily utilized as a carbon source by mercury methylating microorganisms, increasing the abundance or activity of mercury methylating microorganisms. These two results promote the conversion of mercury into the more toxic methylmercury and its enrichment in crops. This phenomenon is more pronounced in high-mercury soils.

[0006] Referring to the prior art, a straw fermentation method and straw return method suitable for mercury-contaminated soil - CN116162004 B, straw is subjected to anaerobic fermentation in a fermentation device containing additives to obtain a fermentation product, wherein the additives are selected from one or more of soluble sulfates, metal sulfides, iron ore and medical stone (i.e., providing SO4 2- ). The additives used in this method are mainly derived from various chemicals, among which sulfate is the most prominent. 2- As a raw material for making mercury remediation materials, it can reduce SO4 in acidic mine drainage 2- , reducing the impact of acid mine drainage discharge on the water environment, soil environment and humans; it can also effectively improve the operating efficiency of the acid mine drainage treatment system; finally, it can realize the resource utilization of pollutants and turn waste into treasure. Summary of the Invention

[0007] The present invention aims to provide a method for producing mercury repair materials by utilizing sulfate in acid mine wastewater, and converting SO4 2- It is removed and converted into sulfur-containing ligand organic matter, which is loaded on straw for utilization. While reducing its impact on the water environment, soil environment and humans, it realizes the resource utilization of pollutants and turns waste into treasure.

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

[0009] This scheme will concentrate SO4 from acid mine drainage 2- Fermented with straw to make SO4 2- It is converted into sulfur-containing ligand organic matter and loaded on straw to form mercury remediation materials.

[0010] Working principle of the present invention:

[0011] After the acid mine drainage flows out from the mine mouth or outflow point, a certain amount of carbonate rock slurry is added to increase the pH of the wastewater. The wastewater is divided into two parts. One part is led to the anaerobic tank. During this process, oxygen should be avoided to ensure that the pH of the acid mine drainage reaches above 5.5 before entering the anaerobic tank. The mine drainage after entering the anaerobic tank is mixed with the biogas liquid led out of the reactor. Through the action of microorganisms such as sulfate-reducing bacteria, SO4 in the acid mine drainage is reduced to 0.5. 2- It is reduced and converted into H2S gas and discharged from the water phase, reducing SO4 in the water 2- content; or converted into S 2- It forms insoluble sulfides with heavy metals in wastewater. The biogas slurry can also provide a certain amount of organic matter for the growth of microorganisms in the anaerobic tank. The amount of biogas added is sufficient to remove SO4 2- The required amount is the goal, and efforts are made to reduce the amount added to reduce the difficulty of COD treatment in the subsequent system. The other part of the mine wastewater is adjusted in pH, mixed with the effluent from the anaerobic tank, and then enters the subsequent aeration tank for further treatment. Since part of the mine wastewater is used for anaerobic reaction, the higher COD concentration can increase SO4 2- The removal efficiency is high, and then it is mixed with mining wastewater that has not undergone anaerobic reaction, which effectively reduces the COD content in the subsequent treated wastewater and reduces the difficulty of subsequent COD removal.

[0012] Fe 2+ / 3+ During the hydrolysis process, a large amount of H + In order to maintain the pH of wastewater at a neutral level, a large amount of carbonate rock will be consumed, which will cause the Ca 2+ The concentration increased significantly in SO4 2-When the concentration is high, Ca in water 2+ and SO4 2- The concentration product exceeds its ion product, causing a large amount of CaSO4 solid to be generated and forming a large number of crystals on the surface of carbonate rock particles, pool walls, pipe walls, equipment inner walls and other areas, thereby destroying the stability of system operation and increasing the difficulty of operation and maintenance management.

[0013] Therefore, the biogas in the reactor is appropriately introduced into the anaerobic tank to remove part of the SO4 2- Reduction is performed to ensure that Ca 2+ and SO4 2- The concentration product is lower than the ion product, thereby reducing the frequency of scaling in various areas of the system. In this process, it is also necessary to avoid excessive introduction of biogas slurry, otherwise it will lead to the formation of higher COD effluent in the anaerobic tank, increase the difficulty of the system in treating COD, and cause waste.

[0014] The mine wastewater flowing out of the anaerobic tank is mixed with the mine wastewater after pH adjustment and then enters the aerobic aeration tank. Fillers that are easy for microorganisms to attach and grow are arranged in the aeration tank, and aeration is carried out and carbonate rock slurry is added. The aeration process is used to convert Fe 2+ Oxidized to Fe 3+ , and then use carbonate rocks and Fe 3+ During the hydrolysis process, H + Neutralize Fe in water 2+ / 3+ Fe(OH)3 solid is formed. In this process, microorganisms can promote the reaction and at the same time, microorganisms can biologically treat COD in the water to achieve COD removal. In the middle of the aeration tank, NaOH is added to raise the pH of the wastewater to above 10.5. Mn 2+ When the pH is above 10.3, the ion concentration of other heavy metal ions can be lower than 10 -5 mol / L, achieving basic removal of heavy metal ions in water. After the pH is raised and the metal ions are converted to solids in the aeration tank, precipitation separation is carried out in the sedimentation tank, so that the solid matter in the wastewater is separated from the water through sedimentation. The supernatant enters the filter tank, and the wastewater after filtering in the filter tank enters the wetland system. The wetland ecosystem is used to continuously treat residual pollutants such as COD in the wastewater before discharge.

[0015] Since the wetland effluent contains a certain concentration of SO4 2- , the wetland effluent can be introduced into SO4 with strong anion resin as needed 2- Concentration system or membrane separation system uses anion resin to absorb SO4 in water 2- The treated water is discharged, and after the resin is saturated with adsorption, NaCl is used to regenerate the resin. The waste liquid after regeneration contains a large amount of SO4 2-(The concentrated liquid in the membrane separation system is rich in SO4 2- , clear liquid SO4 2- Sulfate ions (low content) are used as raw materials for mercury remediation materials. Sulfate ions are introduced into a reactor at a suitable sulfate concentration and co-fermented with straw to produce a mercury remediation material loaded with sulfur-containing organic ligands. This mercury remediation material can be applied to farmland contaminated by mercury and other heavy metals, inhibiting the release of mercury and other heavy metal ions, reducing environmental pollution from straw waste, beautifying the regional environment, and effectively transforming waste into valuable resources.

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

[0017] 1. SO4 produced by treating tail water 2- SO4 contained in the concentrate 2- The principle of generating organic matter containing sulfur ligands under anaerobic conditions with organic matter such as straw is used to prepare mercury remediation materials. While optimizing the acid mine wastewater treatment process, the straw and SO4 2- Resource utilization, turning waste into treasure;

[0018] 2. Use anion resin to remove SO4 in acidic mine wastewater 2- Concentrate to reduce SO4 in the tail water of mine wastewater purification 2- content, increasing the SO4 content in the straw reaction solution 2- concentration (or use membrane separation to separate SO4 2- concentration), reducing the amount of liquid entering the reactor, thereby reducing the amount of sulfate and biogas effluent from the reactor, reducing the amount of wastewater entering the mine water treatment system, and reducing the system processing load;

[0019] 3. The outflowing biogas from the reactor can provide the organic matter required by sulfur-reducing bacteria, which helps to reduce SO4 2- Restore to S 2- , reduce SO4 in wastewater 2- The content of CaSO4 can be reduced, and the subsequent generation of CaSO4 can be reduced, and the formation of a large number of crystal packages in areas such as the surface of carbonate rock particles, pool walls, pipe walls, and inner walls of equipment can be reduced.

[0020] 4. After adding carbonate rock 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, which can achieve the basic removal of heavy metal ions in the water, ensure that there is no significant increase in metal ions in the subsequent reactor, and avoid the introduction of new metal ions into the soil environment during the use of mercury remediation materials.

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

[0022] Preferably, the biogas produced by the reactor is introduced into the anaerobic tank, the wastewater should stay in the anaerobic tank for more than 1 day, and the tank is filled with fillers that are convenient for microbial attachment. 2- Can be partially removed to ensure the remaining SO4 2- and Ca 2+ The concentration product in the treatment system is less than the solubility product. The amount of COD brought into the biogas slurry should be sufficient to ensure the removal of SO4 2- Reduce the amount added based on the required amount to reduce the difficulty of COD treatment in the subsequent system.

[0023] Preferably, a two-stage dosing system is used in aerobic aeration tanks. The first stage uses inexpensive carbonate rock slurry as a neutralizing medium to neutralize the H+ generated during pollutant removal, maintaining the pH between 6.5 and 7.0. NaOH or Ca(OH)2 is added in the middle stage primarily to raise the pH to above 10.5, meeting the requirements for removing manganese and other heavy metals and ensuring that subsequent mercury remediation materials are no longer enriched with heavy metal ions that could pose environmental risks. This two-stage dosing system significantly reduces the use of expensive NaOH or Ca(OH)2, lowering system treatment costs.

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

[0025] Preferably, the SO4-rich 2- The concentrated solution is adjusted to a certain concentration and then sent into the reactor, where it reacts with the straw using anaerobic microorganisms to produce SO4 2- It is converted into sulfur-containing ligand organic matter and attached to the straw, completing the production of mercury remediation materials.

[0026] Preferably, when removing the straw from the reactor, do not remove all of the straw at once. Instead, remove some of the straw and then add new straw. Alternatively, remove all of the straw and then remove some of the remaining straw. The remaining straw is mixed with new straw and then added back into the reactor. The amount of straw removed and added each time should be 20% to 50% of the total amount of straw. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1The present invention is a process flow chart of a method for producing mercury repair materials by utilizing sulfate ions in acid mine wastewater. DETAILED DESCRIPTION

[0028] The following is further described in detail through specific implementation methods:

[0029] Example: After the acid mine wastewater flows out from the mine mouth or outflow point, a certain amount of carbonate rock slurry is added. During this process, oxygen should be avoided to make the wastewater pH reach above 5.5. 2- To remove the demand, part of the wastewater is taken from the supernatant of the acid mine wastewater and sent to the anaerobic tank; the mine wastewater after entering the anaerobic tank is mixed with the biogas introduced by the reactor, and the SO4 in the acid mine wastewater is reduced by the action of microorganisms such as sulfate-reducing bacteria. 2- It is reduced and converted into H2S gas and discharged from the water phase, reducing SO4 in the water 2- The amount of acid mine wastewater entering the anaerobic tank ensures that the Ca content in each treatment unit is 2+ At the maximum concentration, the concentration product of SO4 is less than the solubility product, and the excess SO4 is removed through the anaerobic tank. 2- It can be removed while minimizing the amount of COD flowing out of the anaerobic tank effluent.

[0030] The mine wastewater flowing out of the anaerobic tank is mixed with the mine wastewater that has not entered the anaerobic tank and then enters the aerobic aeration tank. Fillers that are easy for microorganisms to attach and grow are arranged in the aerobic aeration tank, and aeration is carried out and carbonate rock slurry is added. The aeration process is used to convert Fe 2+ Oxidized to Fe 3+ , and then use carbonate rocks and Fe 3+ During the hydrolysis process, H + Neutralize Fe in water 2+ / 3+ Forming Fe(OH)3 solid, in this process, microorganisms can promote Fe 2+ Fe 3+ To carry out oxidation, add NaOH (or Ca(OH)2) in the middle of the aeration tank to raise the pH of the wastewater to above 10.5, and use Mn 2+ When the pH is above 10.3, the ion concentration of other heavy metal ions can be lower than 10 -5 mol / L, achieving basic removal of heavy metal ions in water. After the metal ions are removed in the aeration tank, the wastewater enters the sedimentation tank for mud-water separation. After the solid matter in the wastewater is separated from the water through sedimentation, the supernatant enters the filter tank. The wastewater after filtering in the filter tank enters the wetland system, which uses the wetland ecosystem to continuously treat residual pollutants such as COD in the wastewater before discharge.

[0031] Since the wetland effluent still contains a certain concentration of SO4 2- As needed, a portion of the wetland effluent can be introduced into the SO4 2- Concentration system, using anion resin to absorb SO4 in water 2- The treated water is discharged or reused, and after the resin is saturated with adsorption, NaCl is used to regenerate the resin. The waste liquid after regeneration contains a large amount of SO4 2- , is the raw material for making mercury repair materials, according to SO4 2- The concentration used (referring to the prior art straw fermentation method and straw return method suitable for mercury contaminated soil) introduces SO4 2- In a reactor, the product is co-fermented with straw to produce a mercury remediation material. This mercury remediation material can be applied to farmland contaminated by mercury and other heavy metals, inhibiting the release of mercury and other heavy metal ions from the field. This reduces environmental pollution caused by straw waste, beautifies the regional environment, and effectively transforms waste into valuable resources.

[0032] The specific technical principles are as follows:

[0033] 1. Raw water characteristics: The quality and volume of acid mine drainage water are prone to change with the season and rainfall. The emission indicators involved in acid mine drainage water are mainly pH, Fe 2+ 、Mn 2+ etc., SO4 2- It is not a pollutant that is the focus of attention in sewage-related discharge standards; however, when it comes to drinking water sources, SO4 2- The concentration will be the focus of attention. Secondly, when using calcium-containing alkaline substances to treat acidic wastewater, CaSO4 crystals are easily formed, causing scaling on the pipe walls, device walls, and reaction medium surfaces, which is not conducive to the stable operation of the treatment system.

[0034] Ca 2+ +SO4 2- →CaSO4↓

[0035] 2. Production of sulfides: containing SO4 2- During the anaerobic treatment of wastewater, on the one hand, sulfate-reducing bacteria (SRB) will convert SO4 2- and SO3 2- Utilize it as an electron acceptor, and SO4 2- and SO3 2- Reduced to H2S or S 2- On the other hand, under the action of microorganisms, part of SO4 2- It will be converted into sulfur-containing ligand organic matter, and rich pores will be formed in the straw during the decomposition process, so that the sulfur-containing organic matter will be loaded in the sludge of the fermented straw.

[0036] 3. Anaerobic pollution removal process: The reactivity of H2S with metal ions depends on the type and conditions of metal ions. Under certain conditions, H2S can react with Cu 2+ 、Co 2+ 、Zn 2+ 、Mn 2+ 、Ag + 、Cu + 、Hg 2+ , Pb 2+ etc. (In the case that the system does not contain strong oxidizing substances, the following is n+ represents metal ions) and S 2- The reaction directly produces insoluble precipitates. When these metal ions react with H2S, they can produce corresponding sulfide precipitates; but H2S reacts with Ca 2+ 、Na + Mg 2+ 、Al 3+ In general, there is no reaction. Whether the products of these reactions form a precipitate depends on the solubility of the product and the pH value of the reaction environment. n+ The reaction conditions are conducive to the formation of MS precipitation.

[0037] Mn 2+ +H2S→MnS+2H +

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

[0039] 4. Aerobic removal process of pollutants

[0040] After the front-end anaerobic reaction process, a small amount of Fe 2+ 、Al 3+ Heavy metal ions such as Fe 2+ The oxidizable ions are oxidized and, under low pH conditions, carbonate rock slurry is used to remove a large amount of pollutants. After the pH is raised to 10.3, the remaining heavy metal ions can be basically removed. The oxidation and precipitation removal principle (taking 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 precipitation process

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

[0044] Mn 2+ +2OH - +0.5O2→MnO2↓+H2O

[0045] The following data were obtained by testing wastewater treatment at each stage:

[0046] Table 1 - Reactors

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

[0048] Table 1 shows that the reactor can efficiently remove SO4 through the fermentation process 2- , the reduction rate exceeded 90%, indicating that straw fermentation has a great impact on SO4 2- The adsorption and conversion effects are significant.

[0049] Table 2-Anaerobic tanks

[0050]

[0051]

[0052] From Table 2 we get:

[0053] When the ratio of mine water to biogas liquid is 3:1, SO4 2- From the mixed influent (2338×3+560×1) / 4=1833mg / L to 606mg / L, the removal rate is 67%; when the ratio is increased to 4:1, SO4 2- It only dropped to 794 mg / L, with a removal rate of 57%.

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

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

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

[0057] The COD of the effluent was significantly lower than that of the biogas inlet (873 / 720 vs. 8608), indicating that the anaerobic tank microorganisms provide energy by decomposing organic matter in the biogas slurry and convert SO4 2- Reduced to H2S, achieving the synergistic effect of "carbon source utilization-sulfur reduction".

[0058] During the anaerobic process, H2S release consumes H + At the same time, 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 - Mine Water

[0060]

[0061] From Table 3 we get:

[0062] Efficient removal of heavy metals:

[0063] Fe 2+ / Fe 3+ The concentration dropped from 122 mg / L to 0.1-0.2 mg / L, with a removal rate exceeding 99%, which was attributed to the oxidation of iron ions to Fe in the aerobic aeration tank. 3+ And hydrolyze to form Fe(OH)3 precipitate.

[0064] When the pH is raised to 10.5, Mn 2+ Heavy metal ions such as chlorinated metals are removed through hydroxide or oxide precipitation, and the pH of the wastewater is reduced to below 9.0 during the continuous oxidation process.

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

[0066] SO4 after mixed treatment 2- It only decreased by 15%-19%, indicating that the aerobic stage had a limited contribution to sulfate removal and that the main removal occurred in the anaerobic tank (converted to H2S by sulfur-reducing bacteria).

[0067] Key role of pH adjustment:

[0068] Adding carbonate rock slurry and NaOH (or Ca(OH)2) raises the pH from acidic (4.7) to neutral alkaline (about 10.5), promotes the precipitation of metal ions, and avoids CaSO4 scaling (due to SO4 2- Partially removed during the anaerobic phase).

[0069] In summary, anaerobic tanks: provide carbon source and sulfur-reducing bacteria through biogas slurry, focusing on removing SO4 2- (Removal rate 57%-67%) and part of COD. Aerobic tank: Almost completely remove Fe through oxidation-precipitation 2+ / 3+ 、Mn 2+ Wetland + Filtration: Further degrades COD and stabilizes water quality to ensure discharge meets standards.

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

[0071] The above is only an embodiment of the present invention, and the common knowledge such as the specific structure and characteristics of the scheme is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for producing mercury remediation materials using sulfate in acid mine wastewater, characterized in that: The steps include: S1. Add straw and concentrated SO4 into the reactor 2- The solution is subjected to anaerobic fermentation; S2. Acidic mine wastewater is added with carbonate rock slurry to adjust the pH and then divided into two parts. One part of the wastewater is mixed with the fermentation-generated biogas and then introduced into the anaerobic tank for mine wastewater desulfurization. The effluent from the anaerobic tank is mixed with the other part of the mine wastewater and then enters the aerobic aeration tank for aeration and addition of carbonate rock slurry. NaOH or Ca(OH)2 is added to the middle section of the aeration tank and then led to the sedimentation tank for sedimentation and separation. The supernatant then enters the filter tank and wetland ecosystem to obtain tail water that can be discharged or reused, and the sludge in the sedimentation tank is returned or discharged. S3. Obtain concentrated SO4 from tail water 2- The solution is introduced into a reactor to produce the mercury repair material.

2. The method for producing mercury repair materials using sulfate in acid mine wastewater according to claim 1, characterized in that: The S2 raises the pH of the acid mine drainage water that has just flowed out to above 5.

5.

3. The method for producing mercury repair materials using sulfate in acid mine wastewater according to claim 2, characterized in that: The residence time of S2 acid mine drainage in the anaerobic tank shall not be less than 1 day. The anaerobic tank shall be filled with fillers and mud and water separation shall be carried out.

4. The method for producing mercury repair materials using sulfate in acid mine wastewater according to claim 3, characterized in that: The amount of water entering the anaerobic tank ensures that the SO4 2- and Ca 2+ The concentration product is less than the solubility product; the amount of COD brought into 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 repair materials using sulfate in acid mine wastewater according to claim 4, characterized in that: Carbonate rock slurry is added in the early stage of the treatment process in the aerobic aeration tank to maintain the pH of the acid mine wastewater between 6.5 and 7.0; NaOH or Ca(OH)2 is added in the middle stage of the treatment process to increase the pH of the acid mine wastewater to above 10.

5.

6. The method for producing mercury repair materials using sulfate in acid mine wastewater according to claim 5, characterized in that: The wetland effluent is introduced into the concentration system, which uses membrane treatment or ion exchange resin desalination technology to remove SO4 2- Concentrated, containing SO4 2- The lower treated water is discharged as tail water or reused.

7. The method for producing mercury repair materials using sulfate in acid mine wastewater according to claim 6, characterized in that: Will be rich in SO4 2- The concentrated solution is adjusted to a certain concentration and then sent into the reactor, where it reacts with the straw using anaerobic microorganisms to produce SO4 2- It is converted into sulfur-containing ligand organic matter and attached to the straw, completing the production of mercury remediation materials.

8. The method for producing mercury repair materials using sulfate in acid mine wastewater according to any one of claims 1 to 7, characterized in that: In the reactor, the straw residence time is not less than 30 days, SO4 2- The solution retention time should be no less than 5 days, and a certain amount of additives containing nitrogen and phosphorus should be appropriately added according to the growth conditions of the microorganisms.

9. The method for producing mercury repair materials using sulfate in acid mine wastewater according to claim 8, characterized in that: Take out some straw from the reactor and add new reaction straw.

10. The method for producing mercury repair materials using sulfate in acid mine drainage according to claim 9, characterized in that: The amount of straw taken away and replenished each time is 20% to 50% of the total amount of straw.

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