In-situ treatment method for acidic water seeping from sulfur-containing waste rock heap

Abstract

The invention belongs to the field of wastewater treatment, and particularly relates to an in-situ treatment method for acidic water seeping from a sulfur-containing waste rock pile, which comprises the following steps: drilling and distributing holes in the sulfur-containing waste rock pile to be treated; a sterilizing agent is injected into the drill hole for sterilization treatment, alkali liquor is injected into the drill hole for alkali treatment after sterilization treatment, the drill hole is washed after alkali treatment, and a pretreated drill hole is obtained; the pretreated drill holes are filled with bacteria-loaded porous carbon and ferrous salt, then the holes are sealed, and then in-situ treatment is carried out on the acid water seeping from the sulfur-containing waste rock heap to be treated; the bacteria-loaded porous carbon is obtained by compounding and modifying raw materials including porous carbon, an organic carbon source, activated sludge and sulfate; the activated sludge contains sulfate reducing bacteria and iron reducing bacteria. The method can adapt to hole treatment characteristics, and can realize in-situ long-acting treatment of the acidic water seeping from the sulfur-containing waste rock heap.

Description

Technical Field

[0001] The invention belongs to the field of mine environment management and restoration technology, and specifically relates to the field of in-situ treatment of acidic seepage water from sulfur-containing waste rock piles in mines. Background Art

[0002] After years of stacking, sulfur-containing waste rock piles gradually produce acidic wastewater due to the oxidation of sulfide minerals. The pH value of acidic seepage water is low, and some even reach a pH value of less than 2. During the discharge process, the acidic seepage water has a great impact on the surrounding environment. For some mines that have been closed and rehabilitated, due to the damage of the covering layer or the impermeable layer, the oxidation of sulfides under the action of iron-oxidizing bacteria inside the mine pile produces acidic seepage water. Therefore, under the premise of not disturbing the existing waste rock piles and not re-covering the impermeable layer, the problem of how to control the seepage of acidic water from the source is the focus of the remediation research, given the current situation of acidic seepage water.

[0003] Acid mine drainage (AMD) is recognized worldwide as one of the most serious mining geological environmental problems. Domestic and foreign researchers have been conducting research on acid mine drainage for more than 70 years, and many countries have realized the seriousness of environmental pollution caused by metal mine development. What makes people most uneasy is that even after the mine has been closed for decades, hundreds of years or even longer, the serious impact of acid seepage water on the ecological environment system still exists. The existing AMD treatment solutions are generally divided into end-of-pipe treatment and source in-situ control.

[0004] End-of-pipe treatment is the unified treatment of acid mine wastewater that has already been produced. The main end-of-pipe treatment method currently used is chemical neutralization, which uses lime or limestone to neutralize pH and precipitate heavy metals in the form of hydroxides. For closed mines, the cost of operating the chemical neutralization method is high, and the heavy metal sludge produced by neutralization is easy to dissolve again, causing secondary pollution. Its disposal becomes a major problem in the operation process and increases costs.

[0005] The main idea of ​​in-situ source control is to control the oxidation and dissolution of sulfides such as pyrite. From the steps of AMD production, it can be seen that the key factors for AMD production are pyrite, oxygen, water, and iron-oxidizing bacteria. Controlling individual factors provides ideas for source control of AMD. Existing technologies include burying alkaline substances in abandoned mines and establishing vegetation cover on the surface of abandoned mines. However, due to the wrapping of the neutralization product iron hydroxide on the surface of limestone and the inability of the vegetation cover to alleviate the water quality of acidic wastewater, the above methods have all failed. There is also a shift in technical focus to how to inhibit the dissolution of pyrite from physiological, biochemical, chemical or physical methods. However, research on the source control of pyrite dissolution is still in the laboratory evaluation stage, and no industrial application reports have been seen.

[0006] In recent years, many researchers have used sulfate-reducing bacteria (SRB) to reduce sulfate and increase pH to treat AMD, and developed the SRB process, which has achieved good results. Tuttle et al. first proposed using SRB to treat mine wastewater by adding organic waste as nutrients. Liu Xingyu et al. constructed an upflow anaerobic bioreactor (UASB) using SRB, and combined it with copper and iron precipitation processes to conduct pilot studies in the Zijinshan Gold and Copper Mine. However, the industrial application of the SRB process for treating AMD is not widespread, especially for some waste rock piles that are producing acidic water, and there is a lack of effective industrial in-situ remediation methods. Summary of the invention

[0007] In view of the environmental problems caused by acidic water seeping from sulfur-containing waste rock piles, an in-situ treatment method for acidic water seeping from sulfur-containing waste rock piles is provided to achieve long-term effective and low-cost control of the generation of acidic water seeping from waste rock piles.

[0008] The existing in-situ treatment ideas for acidic water seeping from sulfur-containing waste rock piles are mainly to cover the surface with treatment agents, or to stir the soil layer and modifiers. This method has a slow treatment efficiency and is prone to secondary acid return. In response to this problem, the present invention innovatively provides an in-situ treatment method of drilling and hole arrangement. However, early research and development showed that although the treatment idea of ​​drilling and hole arrangement can reduce the cost of earth stirring and can inject the agent into the soil layer, there will also be new problems, such as insufficient contact interface between the treatment component and the soil, the treatment conditions caused by the geothermal heat in the holes are difficult to control, the treatment efficiency needs to be improved, and it is difficult to play a role in the long term. In addition, for treatment sites that have begun to seep acid water, the difficulty of treatment will be further increased. In response to the problems faced by the in-situ treatment idea of ​​drilling holes in the present invention, the present invention has conducted in-depth research and provides the following improvement scheme:

[0009] The in-situ treatment method of acidic water seeping from the sulfur-containing waste rock pile comprises drilling holes in the sulfur-containing waste rock pile to be treated; injecting a sterilizing agent into the borehole for sterilization treatment, injecting an alkali solution into the borehole for alkali treatment after the sterilization treatment, and washing the borehole after the alkali treatment to obtain a pre-treated borehole;

[0010] Filling the pre-treatment borehole with bacteria-loaded porous carbon and ferrous salts, and then sealing the borehole, thereby in-situ treating the seepage acidic water from the sulfur-containing waste rock pile to be treated;

[0011] The bacteria-carrying porous carbon is obtained by composite modification of raw materials including porous carbon, organic carbon source, activated sludge and sulfate; the activated sludge is activated sludge containing sulfate-reducing bacteria and iron-reducing bacteria.

[0012] The present invention proposes for the first time an in-situ treatment idea for acidic water seeping from a bored sulfur-containing waste rock pile, and in response to the problems faced by the in-situ treatment idea for bored holes, innovatively sterilizes, alkali-treats and acid-washes the holes in advance, and further combines the bacteria-loaded porous carbon of the synergistic component, thereby unexpectedly achieving synergy and adapting to the characteristics of hole treatment, thereby realizing in-situ and long-term treatment of acidic water seeping from a sulfur-containing waste rock pile.

[0013] The method of the present invention can be applied to any waste rock pile that needs to be treated. For example, due to the urgency of treatment and economic value, it is particularly suitable for waste rock piles that have produced acidic seepage water and are difficult to treat with technology within the industry.

[0014] In the present invention, the drilling and hole arrangement can be carried out by using a geological drilling method.

[0015] In the present invention, there is no special requirement for the shape of the hole of the drill, which can be controlled according to the characteristics of the drill bit. For example, it can generally be a circular hole.

[0016] In the present invention, the drilling parameters can be reasonably controlled according to the pollution situation, for example, the drilling hole diameter is 30-100 mm, the drilling depth accounts for 70%-90% of the height of the entire waste rock pile, and the hole spacing is 1-8 m.

[0017] In the present invention, the sterilizing agent is a non-oxidizing sterilizing agent.

[0018] In the present invention, the sterilizing agent is isothiazolinone.

[0019] The sterilizing agent is prepared in advance into a solution with a concentration of 150 to 350 mg / L.

[0020] In the present invention, the sterilization times are 1 to 3 times, and the single action time is 3 to 7 days.

[0021] In the present invention, the alkali solution is an aqueous dispersion of at least one alkaline solute selected from sodium hydroxide and calcium hydroxide.

[0022] Preferably, the concentration of the alkaline solute in the alkali solution is 0.5 wt% to 20 wt%, and can further be 1 to 12 wt%. When the alkaline solute is sodium hydroxide, its concentration can be reduced to 1 to 4 wt%.

[0023] Preferably, the alkali treatment time is 5 to 30 days.

[0024] In the present invention, the washing liquid in the washing stage is water.

[0025] In the present invention, the porous carbon is biochar and / or activated carbon, which can be purchased commercial products or prepared based on conventional carbonization methods.

[0026] In the present invention, on the basis of the above-mentioned sterilization, alkali treatment and washing of the boreholes, further coordinated with the above-mentioned bacteria-loaded porous carbon and the joint control of the materials, synergy can be achieved, the characteristics of the borehole-type in-situ treatment can be adapted, and the efficiency and effect of the borehole-type in-situ treatment can be improved.

[0027] In the present invention, the organic carbon source comprises at least one biomass selected from waste cooking oil, animal excrement, rice straw, stalks and corn cobs and fermentation products thereof.

[0028] Preferably, the organic carbon source accounts for 0.5% to 5% by weight of the porous carbon, and further 1 to 2.5% by weight.

[0029] In the present invention, the activated sludge is taken from a sewage treatment plant or pond or river bottom mud;

[0030] Preferably, the activated sludge accounts for 1% to 5% of the weight of the porous carbon.

[0031] In the present invention, the sulfate is provided by a sulfate solution with a mass concentration of 0.5% to 5%.

[0032] Preferably, the sulfate is at least one of iron sulfate, sodium sulfate or magnesium sulfate.

[0033] Preferably, the sulfate accounts for 1% to 10% by weight of the porous carbon, and further can be 2% to 5%.

[0034] Preferably, the modification stage is carried out under closed conditions.

[0035] Preferably, the modification time is 20 to 50 days.

[0036] In the present invention, the ferrous salt includes ferrous sulfate.

[0037] Preferably, the ferrous salt accounts for 1% to 5% by weight of the bacteria-carrying porous carbon, and further 1 to 2% by weight.

[0038] In the present invention, after filling, clay can be used to cover and seal the holes.

[0039] Preferably, the sulfur-containing waste rock pile is a waste rock pile that produces acidic seepage water, with an S content of 1% to 10%. The pH of the initial acidic seepage water of the sulfur-containing waste rock pile is below 4.

[0040] Beneficial Effects

[0041] (1) The present invention provides an in-situ treatment method for acidic water seeping from a bored sulfur-containing waste rock pile.

[0042] (2) The governance effect is effective and can be maintained for a long time:

[0043] The present invention can transform the internal system of the waste rock pile that has produced acidic seepage water by means of a drilling layout. First, the boreholes are pre-treated with sterilization and alkali treatment, and then the combination of the quaternary component of the bacteria-carrying porous carbon is used, and the microenvironmental characteristics of the drilling treatment method are further matched to transform the system into a long-term reducing condition. The microorganisms in the system reduce sulfate, increase the pH value of the water body, and precipitate the relevant harmful metal ions:

[0044] SO4 2- +2C+2H2O=2HCO3 - +H2S (under the action of anaerobic bacteria)

[0045] (3) Environmentally friendly: The present invention utilizes the strong adsorption capacity of porous carbon to adsorb the carbon source required for the repair process onto the porous structure of the porous carbon. The porous carbon itself is also a carbon source that can be slowly utilized over a long period of time. On the one hand, during the repair process, the organic matter content in the water body will not be released into the water body, causing the organic matter to exceed the standard. On the other hand, it will provide carbon source materials for the growth of anaerobic bacteria for a long time, solving the problem that the existing technology is difficult to provide carbon source materials in a long-term and stable manner. In addition, no exogenous materials and microorganisms are introduced in the repair process. The entire repair process is clean, safe, environmentally friendly, and free of secondary pollution.

[0046] (4) Low cost and wide range of remediation objects: The present invention can improve the treatment effect of microbial technology on acidic water seeping from acidified sulfur-containing waste rock piles, effectively overcome the problems of poor microbial adaptability, low remediation effect and biosafety in existing microbial in-situ treatment technologies, and effectively reduce the economic cost of microbial remediation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a schematic diagram of the process of the present invention;

[0048] Figure 2 The pH values ​​of the effluent from the repair process of Example 1 and Comparative Examples 1 to 4 are shown. DETAILED DESCRIPTION

[0049] The present invention is further described below with reference to the embodiments, but the contents of the present invention are not limited to the described scope.

[0050] A typical in-situ treatment method for acidic water seeping from a sulfur-containing waste rock pile of the present invention comprises the following steps:

[0051] (1) Drilling holes in waste rock piles: Drill holes in waste rock piles by geological drilling;

[0052] (2) Sterilization pretreatment: injecting a sterilizing agent into the hole drilled in step (1);

[0053] (3) Neutralization pretreatment: injecting alkaline solution into the borehole sterilized in step (2);

[0054] (4) Water injection and washing: injecting clean water into the hole drilled in step (3) to wash the hole;

[0055] (5) Preparation of bacteria-loaded porous carbon: fully contact the organic carbon source with the porous carbon so that it is adsorbed into the pores of the porous carbon (or directly use the waste porous carbon that has adsorbed organic matter), then mix it with the activated sludge and place it in a closed device, and inject sulfate solution to prepare the bacteria-loaded porous carbon;

[0056] (6) Injection of bacteria-carrying porous carbon into the hole: Mix ferrous sulfate and the bacteria-carrying porous carbon prepared in step (5) and then inject them into the borehole of the waste rock pile, and then cover and seal the hole with clay;

[0057] (7) Regularly take samples to monitor the quality of seepage water.

[0058] The step (1) specifically comprises: a drilling hole diameter of 30 to 100 mm, a drilling hole depth of 70% to 90% of the height of the entire waste rock pile, and a hole spacing of 1 to 8 m;

[0059] The step (2) is specifically as follows: the sterilizing agent is a commercially available non-oxidizing sterilizing agent, the main component of which isothiazolinone, the sterilization times are 1 to 3 times, and the single action time is 3 to 7 days;

[0060] The step (3) specifically comprises: injecting 0.5% to 5% sodium hydroxide alkali solution or 5% to 20% calcium hydroxide slurry into the borehole, and performing alkali treatment for 5 to 30 days;

[0061] The step (4) specifically includes: injecting clean water to wash the borehole, the purpose of which is to clean or dilute the residual sterilizing agent and the unreacted alkali solution around the borehole, and the specific amount of water used for washing is determined according to the specific conditions of the waste rock pile site;

[0062] The step (5) is specifically as follows: the porous carbon is fully contacted with an organic carbon source (waste porous carbon that has adsorbed organic matter may also be directly used), and then mixed with 1% to 5% of activated sludge and placed in a tower or tank-type closed container, and a sulfate solution with a mass concentration of 0.5% to 5% is injected to prepare the bacteria-loaded porous carbon; the organic carbon source may be one or more fermentation liquids of waste cooking oil, animal feces, rice straw, stalks and corn cobs, or an organic compound product may be directly used according to local conditions; the activated sludge is taken from a sewage treatment plant or pond or riverbed mud; the bacteria-loaded porous carbon is sealed and cultured at room temperature for 20 to 50 days;

[0063] The step (6) specifically comprises: mixing ferrous sulfate particles at a ratio of 1% to 5% into the bacteria-loaded porous carbon cultured in step (5), injecting the particles into the borehole of the waste rock pile, and finally covering the top with clay to seal the hole.

[0064] The step (7) specifically includes: regularly collecting seepage water samples for analysis of pH, ORP, TOC and related harmful metal ions.

[0065] raw material

[0066] The porous carbon described in the present invention can be a conventional commercial product in the industry, or can be prepared based on conventional means. For example, as an optional solution, the porous carbon in the following case is fruit shell activated carbon with a particle size of 50-200 mesh and a specific surface area of ​​>950m 2 / g, strength>90%, iodine adsorption value>800mg / g, which comes from Jiangsu Qisheng Carbon Industry.

[0067] Activated sludge can be obtained from domestic sewage treatment plants or directly from black ponds and riverbed mud. The main active bacteria are sulfate-reducing bacteria and iron-reducing bacteria (bacterial content>10 4 / g sludge).

[0068] It should be noted that, in order to compare the experimental results, the test was conducted in an area with the same physicochemical properties, and the difference in the initial pH of the water discharged from the borehole was controlled within 0.2.

[0069] Example 1

[0070] A uranium mine in southern my country has produced a large amount of waste rock piles containing sulfide (sulfur content in the waste rock is 5.2%) in the mining process for many years, which are piled up in the valley of the mining area, forming more than ten waste rock piles of different sizes. After being treated many years ago, acidic seepage water is now produced due to the damage of the anti-seepage layer, and the pH value of the seepage water is 2-4. The technology of the present invention is used to carry out industrial implementation of microbial in-situ treatment of the largest waste rock pile A, which includes the following steps:

[0071] (1) A nearby drilling team is responsible for drilling holes on the waste rock pile with a hole diameter of 50 mm and a drilling depth of 80% (±5%) of the entire waste rock pile height, with a hole spacing of 2.5 m;

[0072] (2) Purchase KS-370 non-oxidizing sterilant (main component isothiazolinone) sold by Shandong Aike Water Treatment Co., Ltd., prepare it with clean water to a concentration of 200 mg / L, and inject it into each borehole for sterilization twice, with a single action time of 4 days;

[0073] (3) injecting calcium hydroxide slurry with a mass concentration of about 12% into the borehole, neutralizing and waiting for the reaction for 20 days;

[0074] (4) Inject a certain amount of clean water into the borehole to wash the hole to clean or dilute the residual sterilant and unreacted alkali solution around the borehole;

[0075] (5) Abandoned porous carbon (carbon material obtained by using the above-mentioned fruit shell carbon to adsorb organic matter) from a water treatment workshop of a nearby chemical plant was used. The content of organic matter adsorbed by the carbon was 1.14% by weight of the porous carbon. The carbon was mixed with activated sludge from a sewage treatment plant at a weight of 1.2% by weight of the porous carbon and placed in a tower-type closed equipment. A 1% mass concentration of iron sulfate solution was injected to prepare bacteria-loaded porous carbon. The solute injection amount in the iron sulfate solution was 5% by weight of the porous carbon. The carbon was sealed and cultured at room temperature for 25 days.

[0076] (6) Mix ferrous sulfate particles at a ratio of 1.5% into the bacteria-loaded porous carbon cultured in step (5), and inject it into the borehole of the waste rock pile, and finally cover the top with clay to seal the hole.

[0077] (7) Regularly analyze the pH, ORP, TOC and related harmful metal ions of the seepage water samples.

[0078] Comparative Example 1

[0079] Compared with Example 1, the only difference is that in step 5, the porous carbon is replaced by an equal weight of crop straw powder, and the other conditions are the same as in Example 1.

[0080] Comparative Example 2

[0081] Compared with Example 1, the only difference is that steps 2 and 3 are not performed, and step 4 and subsequent treatments are directly performed after step 1, and the other conditions are the same as in Example 1.

[0082] Comparative Example 3

[0083] Compared with Example 1, the only difference is that in step 5, no organic matter is added (the porous carbon does not pre-adsorb organic matter), and the other conditions are the same as Example 1.

[0084] Comparative Example 4

[0085] Compared with Example 1, the only difference is that in step 5, the ferrous sulfate of step 6 is not added, and the other conditions are the same as in Example 1.

[0086] On-site repair effect monitoring:

[0087] For Example 1 and Comparative Examples 1 to 4, the seepage water repair effect was monitored to ensure the effectiveness and environmental safety of the repair process. The pH values ​​of the effluent from each scheme of the repair process are shown in the figure below.

[0088] The specific restoration data (sampling on the 400th day) are shown in the following table (except pH, the unit is mg / L):

[0089]

[0090]

[0091] It can be seen from the above figure and table that, compared with Comparative Examples 1 to 4, the inhibition system in the waste rock pile of Example 1 is quickly established and remains effective for a long time. From the 20th day onwards, the pH value of the seepage water has been maintained at 6.5-7.5 for a long time, and U has not been detected in the seepage water. The concentrations of other metal ions have reached the emission standards. Since Comparative Example 1 did not use porous carbon, the pH value of its seepage water gradually decreased from 200 days, and the seepage water from 50 to 150 days was black, and the organic matter content exceeded the standard. Since Comparative Example 2 did not use sterilization and neutralization pretreatment, the microorganisms were severely inhibited in the acidic system. During the entire repair period, the pH value of the seepage water was below 4.0. The porous carbon used in Comparative Example 3 did not compound the organic carbon source, resulting in insufficient release of the carbon source material in the system. The pH value of the seepage water gradually decreased after 250 days. Comparative Example 4 did not use the synergistic effect of ferrous iron. Due to Fe 2+ It has a stimulating effect on the growth of reducing bacteria, resulting in a lower overall pH value compared with Example 1, and the ideal repair effect was not achieved.

[0092] The cost required for the industrial treatment method of this technology is only the cost of drilling and preparing bacteria-loaded activated carbon, which are all one-time investments. The treatment effect is effective in the long term and there is no overall maintenance cost. If the control force is reduced after a long period of time, the existing drilled holes can be used to implant new bacteria-loaded porous carbon again.

[0093] Example 2

[0094] The method of the present invention was used to industrially treat the acidic seepage water produced by the sulfide-containing waste rock pile (sulfur content 8.8%) stripped during the mining and production process of a nickel-molybdenum mine. The pH value of the waste rock pile seepage water was less than 3, and some heavy metal ions exceeded the emission standard. The waste rock pile was treated by microbial in-situ industrialization using the technology of the present invention, including the following steps:

[0095] (1) A geological brigade is responsible for drilling holes on the waste rock pile. The hole diameter is 75 mm, the drilling depth accounts for about 70% of the height of the entire waste rock pile, and the hole spacing is 5 m;

[0096] (2) Purchase a commercially available non-oxidizing sterilant (main ingredient isothiazolinone) from a certain company, prepare it with clean water to a concentration of ~300 mg / L, and inject it into each borehole for sterilization once for 5 days;

[0097] (3) injecting a sodium hydroxide solution with a mass concentration of 1% into the borehole and treating with alkali for 7 days;

[0098] (4) Inject a certain amount of clean water into the borehole to wash the hole to clean or dilute the residual sterilant and unreacted alkali solution around the borehole;

[0099] (5) Using waste porous carbon that has adsorbed organic matter (waste cooking oil), the organic matter accounts for 2.1% of the weight of the porous carbon, and then mixing it with 1.2% of the weight of activated sludge from a sewage treatment plant, the mixture is placed in a tower-type closed container, and a 1.5% mass concentration sodium sulfate solution (the solute injection amount in the sodium sulfate solution is 4% of the weight of the porous carbon) is injected to prepare bacteria-loaded porous carbon, and the mixture is sealed and cultured at room temperature for 22 days;

[0100] (6) Mix ferrous sulfate powder at a ratio of 1% into the bacteria-loaded porous carbon cultured in step (5), and inject it into the borehole of the waste rock pile, and finally cover the top with clay to seal the hole.

[0101] (7) Regularly analyze the pH, ORP, TOC and related harmful metal ions of the seepage water samples.

[0102] For Example 2, the seepage water remediation effect was monitored to ensure the effectiveness and environmental safety of the remediation process. The results showed that after 20 days of injection of the bacteria-loaded porous carbon into the borehole, the pH value of the system reached above 6.0, and long-term testing showed that the TOC and major metal ion concentrations met the emission standards.

[0103] Example 3

[0104] The method of the present invention was used to industrially treat the acidic seepage water generated by the sulfur-containing waste rock pile (sulfur content 7.89%) stored during the mining and production process of a copper mine in Jiangxi. The pH value of the seepage water from the waste rock pile was 1-2, and some heavy metal ions exceeded the emission standard. The waste rock pile was treated by microbial in-situ industrialization using the technology of the present invention, including the following steps:

[0105] (1) An exploration team is responsible for drilling holes on the waste rock pile. The hole diameter is 55 mm, the drilling depth accounts for about 80% of the height of the entire waste rock pile, and the hole spacing is 4 to 5 m;

[0106] (2) Purchase a commercially available non-oxidizing sterilant (main ingredient isothiazolinone) from a certain company, prepare it with clean water to a concentration of ~300 mg / L, and inject it into each borehole for sterilization three times, with a single action time of 4 to 5 days;

[0107] (3) injecting a sodium hydroxide solution with a mass concentration of 3.5% into the borehole and treating with alkali for 6 days;

[0108] (4) Inject a certain amount of clean water into the borehole to wash the hole to clean or dilute the residual sterilant and unreacted alkali solution around the borehole;

[0109] (5) The newly purchased fruit shell porous carbon from Jiangsu Qisheng Carbon Industry was fully adsorbed and contacted with the industrial-grade organic compound lactic acid solution, and 1.88% of the lactic acid by weight of the porous carbon was adsorbed into the porous medium, and then mixed with 5% of the pond bottom mud and placed in a trough-type closed container, and a 0.85% mass concentration of sulfate (sodium sulfate) solution (the solute injection amount in the sulfate solution is 4.5% of the weight of the porous carbon) was injected to carry out the bacteria-loaded porous carbon sealed culture at room temperature for 33 days;

[0110] (6) Mix ferrous sulfate powder at a ratio of 1.2% into the bacteria-loaded porous carbon cultured in step (5), and inject it into the borehole of the waste rock pile. Finally, cover the top with clay to seal the hole.

[0111] (7) Regularly analyze the pH, ORP, TOC and related harmful metal ions of the seepage water samples.

[0112] For Example 3, the effectiveness and environmental safety of the remediation process were ensured through long-term monitoring. The results showed that after 23 days of injection of the bacteria-loaded porous carbon into the borehole, the pH value of the system reached above 6.4, and the TOC and major metal ion concentrations reached the emission standards since 350 days of monitoring.

Claims

1. An in-situ treatment method for acidic water seeping from a sulfur-containing waste rock pile, characterized in that: Drill holes in the sulfur-containing waste rock pile to be treated; inject a sterilizing agent into the borehole for sterilization treatment, inject alkali solution into the borehole for alkali treatment after the sterilization treatment, and wash the borehole after the alkali treatment to obtain a pre-treated borehole; Filling the pre-treatment borehole with bacteria-loaded porous carbon and ferrous salts, and then sealing the borehole, thereby in-situ treating the seepage acidic water from the sulfur-containing waste rock pile to be treated; The bacteria-carrying porous carbon is obtained by composite modification of raw materials including porous carbon, organic carbon source, activated sludge and sulfate; The activated sludge is activated sludge containing sulfate-reducing bacteria and iron-reducing bacteria.

2. The in-situ treatment method for acidic water seeping from sulfur-containing waste rock piles according to claim 1, characterized in that: Use geological drilling to drill holes; Preferably, the borehole diameter is 30-100 mm, the borehole depth accounts for 70%-90% of the height of the entire waste rock pile, and the hole spacing is 1-8 m.

3. The in-situ treatment method for acidic water seeping from sulfur-containing waste rock piles according to claim 1, characterized in that: The sterilizing agent is a non-oxidizing sterilizing agent; Preferably, the sterilizing agent is isothiazolinone; Preferably, the sterilization times are 1 to 3 times, and the single action time is 3 to 7 days.

4. The in-situ treatment method for acidic water seeping from sulfur-containing waste rock piles according to claim 1, characterized in that: The alkali solution is an aqueous dispersion of at least one alkaline solute selected from sodium hydroxide and calcium hydroxide; Preferably, the concentration of the alkaline solute in the alkali solution is 0.5% to 20%; Preferably, the alkali treatment time is 5 to 30 days.

5. The in-situ treatment method for acidic water seeping from sulfur-containing waste rock piles according to claim 1, characterized in that: The washing liquid in the washing stage is water.

6. The in-situ treatment method for acidic water seeping from sulfur-containing waste rock piles according to claim 1, characterized in that: The porous carbon is biochar and / or activated carbon.

7. The in-situ treatment method for acidic water seeping from sulfur-containing waste rock piles according to claim 1, characterized in that: The organic carbon source comprises at least one biomass selected from waste cooking oil, animal feces, rice straw, stalks and corn cobs and fermentation products thereof; Preferably, the organic carbon source is 0.5% to 5% by weight of the porous carbon.

8. The in-situ treatment method for acidic water seeping from sulfur-containing waste rock piles according to claim 1, characterized in that: The activated sludge is taken to the sewage treatment plant or the bottom mud of ponds and rivers; Preferably, the activated sludge accounts for 1% to 5% of the weight of the porous carbon.

9. The in-situ treatment method for acidic water seeping from sulfur-containing waste rock piles according to claim 1, characterized in that: The sulfate is provided by a sulfate solution with a mass concentration of 0.5% to 5%; Preferably, the sulfate is at least one of iron sulfate, sodium sulfate or magnesium sulfate; Preferably, the sulfate is 1% to 10% by weight of the porous carbon; Preferably, the modification stage is carried out under closed conditions; Preferably, the modification time is 20 to 50 days.

10. The in-situ treatment method for acidic water seeping from sulfur-containing waste rock piles according to claim 1, characterized in that: Ferrous salts include ferrous sulfate; Preferably, the ferrous salt is 1% to 5% by weight of the bacteria-carrying porous carbon; Preferably, the sulfur-containing waste rock pile is a waste rock pile that produces acidic seepage water, and the sulfur content is 1% to 10%.

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