An acid method for uranium groundwater bioremediation based on hierarchical feeding of organic carbon sources

Abstract

The application provides an acid method uranium mining groundwater bioremediation method based on organic carbon source grading addition, and relates to the technical field of uranium mining wastewater treatment. The method comprises the following steps: (1) extracting acid method uranium mining groundwater from an acid method in-situ leaching uranium ore aquifer, and obtaining treated acid method uranium mining groundwater after filtration and pH adjustment; (2) mixing the treated acid method uranium mining groundwater with a nitrogen source and potassium dihydrogen phosphate, and adding an organic carbon source to obtain a liquid culture medium; (3) inoculating sulfate-reducing bacteria in the liquid culture medium, and expanding the culture until the OD value is at least 2 to obtain a bioremediation bacterial solution; and (4) mixing a fixed amount of bioremediation bacterial solution with the acid method uranium mining groundwater every 10 days to repair, wherein the fixed amount of bioremediation bacterial solution is 15% or 25% of the total volume of the bioremediation bacterial solution. The application can realize in-situ sustainable, economical and efficient bioremediation, and reduces the in-situ groundwater remediation cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of in-situ leaching uranium wastewater treatment, and particularly relates to an acid leaching uranium groundwater bioremediation method based on graded addition of organic carbon sources. BACKGROUND

[0002] The carbon source is a carbon-containing element compound that can provide nutrients for the growth and metabolism of microorganisms in a biochemical treatment system of wastewater. The carbon source is divided into single carbon source and composite carbon source. The single carbon source is a carbon source containing only one effective carbon source component. The composite carbon source is a carbon source composed of two or more effective carbon source components, which are compatible and have no chemical reaction and no safety risk.

[0003] The sulfate-reducing bacteria is a biological catalyst that can self-propagate and can reduce SO4 2- to S 2- by metabolism, thereby removing sulfate and heavy metal ions, being non-toxic and harmless to the environment, not causing secondary pollution, and being widely applicable and environmentally friendly. However, the sulfate-reducing bacteria requires sufficient carbon sources when treating acid in-situ leaching uranium groundwater, and a large amount of carbon sources is expensive, so the cost of treating acid in-situ leaching uranium groundwater is very high. However, there is no related report on using cost-saving carbon sources to play a biological reduction role to continuously and efficiently remove sulfate and uranium ions in acid in-situ leaching uranium groundwater and reduce the pollution degree of the water body.

[0004] Therefore, how to provide an in-situ acid in-situ leaching uranium groundwater treatment method capable of supplementing a large amount of carbon sources continuously and efficiently and saving cost to solve the technical problem of high cost of treating acid in-situ leaching uranium wastewater in the prior art is a problem that needs to be solved by those skilled in the art. SUMMARY

[0005] The main purpose of the present application is to provide an acid in-situ leaching uranium groundwater bioremediation method based on graded addition of organic carbon sources, which is safe and reliable in operation, simple in process, and cost-saving.

[0006] In order to achieve the above purpose, the present application provides the following technical solutions:

[0007] The present application provides a bioremediation method for treating acid in-situ leaching uranium groundwater, comprising the following steps:

[0008] (1) extracting acid in-situ leaching uranium groundwater from an acid in-situ leaching uranium ore containing aquifer, and obtaining treated acid in-situ leaching uranium groundwater after filtration and pH adjustment;

[0009] (2) mixing the treated acid in-situ leaching uranium groundwater with a nitrogen source and potassium dihydrogen phosphate, and adding an organic carbon source to obtain a liquid culture medium;

[0010] (3) inoculating the sulfate-reducing bacteria in the liquid medium and expanding the culture to an OD value of at least 2 to obtain a bioremediation bacterial solution;

[0011] (4) daily extracting a fixed amount of bioremediation bacterial solution accounting for 15% or 25% of the total volume of the bioremediation bacterial solution and injecting the bioremediation bacterial solution into the groundwater in the in-situ microbial remediation of the acid leaching terminal mining area;

[0012] The organic carbon source is added in the form of sodium lactate for 22 days and then molasses for 23 days.

[0013] Preferably, in step (4), a fixed amount of bioremediation bacterial solution accounting for 15% or 25% of the total volume of the bioremediation bacterial solution is extracted daily, and the volume ratio of the bioremediation bacterial solution extracted alternately is 15% and 25% with an interval of 10 days; and the remediation time is 45 days.

[0014] The method of extracting a fixed amount of bioremediation bacterial solution accounting for 15% or 25% alternately with an interval of 10 days in step (4) refers to extracting a fixed amount of bioremediation bacterial solution accounting for 15% of the total volume of the bioremediation bacterial solution daily and mixing the bioremediation bacterial solution with the groundwater in the acid leaching uranium mining area for remediation from the 1st to the 10th day; after 10 days, a fixed amount of bioremediation bacterial solution accounting for 25% of the total volume of the bioremediation bacterial solution is extracted daily and mixed with the groundwater in the acid leaching uranium mining area for remediation; after 20 days, a fixed amount of bioremediation bacterial solution accounting for 15% of the total volume of the bioremediation bacterial solution obtained in step (3) and having an OD value of at least 2 is extracted daily and mixed with the groundwater in the acid leaching uranium mining area for remediation; after 30 days, a fixed amount of bioremediation bacterial solution accounting for 25% of the total volume of the bioremediation bacterial solution is extracted daily and mixed with the groundwater in the acid leaching uranium mining area for remediation; and from the 41st to the 45th day, a fixed amount of bioremediation bacterial solution accounting for 15% of the total volume of the bioremediation bacterial solution is extracted daily and mixed with the groundwater in the acid leaching uranium mining area for remediation.

[0015] Preferably, the filtration is performed by using a filter bag with a pore size of 5-20 μm to trap large particles in the groundwater; and the pH value is 3-4.

[0016] Preferably, in step (2), the liquid medium contains sulfate, uranium and iron ions.

[0017] Preferably, the concentration of sulfate in the liquid medium is 900-2500 mg / L, the concentration of uranium is 0.1-0.5 mg / L, and the concentration of iron ions is 50-150 mg / L.

[0018] Preferably, the volume ratio of the seed solution of the sulfate-reducing bacteria to the liquid medium is 0.5%-5%; and the sulfate-reducing bacteria are GDMCC 1.537 strains.

[0019] Preferably, in step (3), the expansion culture is performed under the conditions of controlling the pH value to be 5.0-5.5 and the temperature to be 20-25°C.

[0020] Preferably, in step (3), after adding the organic carbon source, the weight ratio of the acid method uranium mining groundwater, organic carbon source, nitrogen source and potassium dihydrogen phosphate is 10000:10-20:0.5-2:0.1-0.2.

[0021] In the application, the repair is carried out in a continuous culture pumping system, and the system comprises a submersible pump, a flow meter, a filter, a buffer adjusting tank, a transfer pump, a culture medium ingredient tank, a microbial culture tank, a liquid injection mixing tank and a liquid injection pump.

[0022] The application adopts the mode of adding sodium lactate first and then adding Xinjiang sugar beet molasses, which can effectively improve the starting speed of the GDMCC 1.537 strain and reduce the carbon source cost.

[0023] Compared with the prior art, the application has the following beneficial effects:

[0024] The biological repair method for treating acid method uranium mining groundwater has obvious advantages, and by reasonably regulating and controlling the type and order of carbon source grading addition of the continuous culture tank, the expansion efficiency of the GDMCC 1.537 strain is increased, and efficient and continuous in-situ groundwater biological repair is realized. The application adopts the mode of adding sodium lactate first and then adding Xinjiang sugar beet molasses, which can effectively improve the starting speed of the GDMCC 1.537 strain and reduce the carbon source cost. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a schematic diagram of the continuous culture pumping system of the application; wherein 1 is a submersible pump, 2 is a flow meter, 3 is a filter, 4 is a buffer adjusting tank, 5 is a transfer pump, 6 is a culture medium ingredient tank, 7 is a microbial culture tank, 8 is a liquid injection mixing tank, and 9 is a liquid injection pump. DETAILED DESCRIPTION

[0026] The application provides a biological remediation method for treating acid uranium mining groundwater, wherein the volume ratio of the biological remediation bacteria liquid extracted in step (4) is alternately 15% and 25% with an interval of 10 days, which means that 1-10 days, the volume ratio of the biological remediation bacteria liquid extracted is 15% and mixed with the acid uranium mining groundwater for remediation; 10 days later, the volume ratio of the biological remediation bacteria liquid extracted is 25% and mixed with the acid uranium mining groundwater for remediation; 20 days later, the volume ratio of the biological remediation bacteria liquid extracted is 15% and mixed with the acid uranium mining groundwater for remediation; 30 days later, the volume ratio of the biological remediation bacteria liquid extracted is 25% and mixed with the acid uranium mining groundwater for remediation; 41-45 days, the volume ratio of the biological remediation bacteria liquid extracted is 15% and mixed with the acid uranium mining groundwater for remediation.

[0027] The biological remediation method for treating acid uranium mining groundwater provided by the application is carried out in a continuous culture pumping and injecting system, and the system comprises a submersible pump, a flow meter, a filter, a buffer adjusting tank, a transfer pump, a culture medium ingredient tank, a microbial culture tank and a liquid injection mixing tank.

[0028] In the above system, the application realizes the optimization of the injection amount of the functional bacteria agent and the final pumping and injecting ratio of the biological remediation bacteria liquid by multiple tests on different types of organic carbon sources, dosing ratios and sequences, so that in-situ biological sustainable, economic and efficient remediation is realized, and the cost of in-situ groundwater remediation is reduced.

[0029] The biological remediation steps for treating acid uranium mining groundwater by using the above system comprise the following steps:

[0030] The acid uranium mining groundwater pollution raw water is extracted from the acid uranium mining groundwater, and is sequentially treated by the filter and the buffer regulator to obtain treated acid uranium mining groundwater pollution raw water; the treated acid uranium mining groundwater pollution raw water is mixed with the nitrogen source and potassium dihydrogen phosphate in the culture medium ingredient tank, and then the organic carbon source is added: sodium lactate is added for 22 days, and then molasses is added for 23 days, and then the mixture is added to the microbial culture tank, inoculated with the sulfate-reducing bacteria liquid and then expanded, expanded to an OD value of 2, and then the biological remediation bacteria liquid is obtained; 15% or 25% of the total amount of the biological remediation bacteria liquid with an OD value of 2 is pumped into the liquid injection mixing tank through the flow meter to control the flow rate to be 50 L / min every day, and finally injected into the polluted area of the uranium mine groundwater aquifer through the liquid injection pump to perform in-situ remediation of the acid uranium mining groundwater.

[0031] Specifically, the filter adopts a bag filter, specifically a filter bag with a pore size of 5 μm to trap large particles in the groundwater; industrial soda is added in the buffer regulator to control the pH value of the extracted water to maintain 4; in the medium preparation tank, the treated acid method uranium mining groundwater pollution raw water, organic carbon source, nitrogen source and potassium dihydrogen phosphate are proportioned by weight at 10000:20:2:0.2; the nitrogen source is protein peptone; the organic carbon source in the medium preparation tank is added in the form of sodium lactate for 22 days and then added in the form of molasses for 23 days; the medium preparation tank also adds sulfate, uranium and iron ions; optionally, the concentration of sulfate in the liquid medium after adding the organic carbon source in the medium preparation tank is 1800 mg / L, the concentration of uranium is 0.5 mg / L, and the concentration of iron ions is 120 mg / L;

[0032] The volume ratio of the sulfate-reducing bacteria seed liquid to the liquid medium is 5%; the sulfate-reducing bacteria are preferably GDMCC 1.537 strains;

[0033] In the medium preparation tank, after inoculating the GDMCC 1.537 strains, the pH of the microbial culture tank is controlled at 5.5, the temperature is controlled at 25℃, and the top stirring speed is controlled at 100 rpm.

[0034] Further, the preparation method of the sulfate-reducing bacteria liquid is as follows: 0.1 g of activated freeze-dried bacteria GDMCC 1.537 is dissolved in 0.1 mL of sterile water and inoculated on a blood agar plate, and cultured at 30℃ in an anaerobic dark condition until colonies grow on the plate, then 10 mL of modified Bar sulfate liquid medium is used for enrichment culture to the logarithmic phase, and the bacterial concentration is adjusted to OD=2 to obtain the sulfate-reducing bacteria seed liquid for inoculation.

[0035] As an implementable manner, a fixed amount of 15% or 25% of the total amount of the biological repair bacteria liquid reaching an OD value of at least 2 is pumped into the liquid injection mixing tank through a flow meter controlling the flow rate at 50 L / min every day, and finally injected back to the uranium mine underground aquifer pollution area through a liquid injection pump for in-situ microbial repair of acid leaching of the groundwater in the final mining area. The selection method of the fixed amount of 15% or 25% of the total amount of the biological repair bacteria liquid reaching an OD value of 2 is as follows: the 15% or 25% fixed amount of the biological repair bacteria liquid is extracted alternately in intervals of 10 days; the repair time is 45 days.

[0036] The 15% or 25% fixed amount of the bioremediation bacteria liquid in step (4) is extracted alternately in 10 days, that is, in the first 10 days, 15% of the fixed amount of the bioremediation bacteria liquid of the total amount of the bioremediation bacteria liquid reaching OD value 2 in step (3) is extracted daily and mixed with the acid method uranium mining groundwater for remediation; after 10 days, 25% of the fixed amount of the bioremediation bacteria liquid of the total amount of the bioremediation bacteria liquid reaching OD value 2 in step (3) is extracted daily and mixed with the acid method uranium mining groundwater for remediation; after 20 days, 15% of the fixed amount of the bioremediation bacteria liquid of the total amount of the bioremediation bacteria liquid reaching OD value 2 in step (3) is extracted daily and mixed with the acid method uranium mining groundwater for remediation; after 30 days, 25% of the fixed amount of the bioremediation bacteria liquid of the total amount of the bioremediation bacteria liquid reaching OD value 2 in step (3) is extracted daily and mixed with the acid method uranium mining groundwater for remediation; after 41 days to 45 days, 15% of the fixed amount of the bioremediation bacteria liquid of the total amount of the bioremediation bacteria liquid reaching OD value 2 in step (3) is extracted daily and mixed with the acid method uranium mining groundwater for remediation; the mode is called 15% or 25% extraction and injection alternation mode every 10 days.

[0037] The present application can effectively improve the starting speed of GDMCC 1.537 strain by adding sodium lactate first and then adding Xinjiang sugar beet molasses, and can reduce the cost of carbon source, and when the 15% or 25% volume ratio of the bioremediation bacteria liquid extraction and injection alternation mode is used, the starting speed of GDMCC 1.537 strain is further improved, and when the 15% or 25% extraction and injection alternation mode is used every 10 days, the accumulation of hydrogen sulfide can be effectively alleviated, the actual value of hydrogen sulfide is stabilized at 50-95 mg / L, the growth amount of the bacteria agent is improved, the maximum injection amount of biomass is obtained within 45 days, and the groundwater remediation effect is the best.

[0038] In the present application, the factors affecting the injection biomass are mainly determined by the volume of bacteria injection and the concentration of bacteria, and the concentration of bacteria is mainly determined by the growth rate of functional microorganisms, and the growth rates of different organic carbon sources for sulfate utilization are different, the present application compares different organic carbon sources, and finds that Xinjiang sugar beet molasses can achieve the same growth rate and remediation effect as ethanol, and the cost is only 20% of that of sodium lactate, and the optimal remediation time and remediation cost can be realized by scientific regulation of the carbon source addition mode.

[0039] The in-situ acid method uranium mining groundwater bioremediation method of the continuous culture extraction and injection system coupled with carbon source staged addition has obvious advantages, by reasonably regulating the carbon source staged addition type, ratio and sequence of the continuous culture tank and the like parameters, the expansion efficiency of functional microorganisms is increased, and high-efficiency in-situ groundwater bioremediation is realized. Sulfate-reducing bacteria can be continuously propagated, are non-toxic and harmless to the environment, and will not cause secondary pollution, and by reasonably regulating the extraction and injection ratio of the bacteria agent and nutrients, the in-situ sustainable and economic high-efficiency remediation can be realized, and the in-situ groundwater remediation cost is reduced.

[0040] The strain used in the application is Desulfovibrio desulfuricans subsp. Desulfuricans, which is provided by Guangzhou Provincial Microbial Culture Collection Center (GDMCC) and has a preservation number of GDMCC 1.537. The strain has a number of American Type Culture Collection (ATCC) of 7757.

[0041] Xinjiang sugar beet molasses is purchased from Cargill Tunhe Sugar Industry Co., Ltd.

[0042] The test methods used in the following examples are conventional methods unless otherwise specified; the materials, reagents, etc. used are commercially available reagents and materials unless otherwise specified.

[0043] The technical solutions provided by the application will be described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the application.

[0044] Example 1

[0045] 1. Construction of continuous culture pumping system

[0046] According to the schematic diagram of the self-designed continuous culture pumping system shown in Figure 1 , the system is constructed; the continuous culture pumping system includes a submersible pump, a flow meter, a filter, a buffer adjustment tank, a transfer pump, a culture medium ingredient tank, a microbial culture tank, a liquid injection mixing tank, and a liquid injection pump.

[0047] 2. Acid method uranium mine groundwater remediation using continuous culture pumping system

[0048] The continuous culture pumping system designed by the inventors is used to test and study the groundwater sample of the 3-9461 drill hole mine of Xinjiang Yili 737 uranium mine. Figure 1

[0049] The contaminated raw water is pumped from the acid leaching uranium ore aquifer of the 3-9461 drill hole mine of Xinjiang Yili 737 uranium mine, a filter bag with a pore size of 5 μm is used to intercept large particles in the groundwater, and then a buffer regulator is used to add industrial sodium carbonate to control the pH value of the pumped water to maintain at 4.

[0050] ​The treated acid method uranium ore groundwater is then injected into a culture medium preparation tank. The culture medium preparation tank is supplemented with protein peptone (nitrogen source), potassium dihydrogen phosphate and organic carbon source at a constant speed of 1 L / min. The treated acid method uranium ore groundwater, organic carbon source, protein peptone (nitrogen source) and potassium dihydrogen phosphate are mixed at a weight ratio of 10,000:20:2:0.2 in the culture medium preparation tank to obtain a liquid culture medium. The concentration of sulfate in the liquid culture medium is 1,800 mg / L, the concentration of uranium is 0.5 mg / L, and the concentration of iron ions is 120 mg / L. The organic carbon source is added in stages during the treatment process. The organic carbon source is added in the form of sodium lactate for 22 days and then added in the form of molasses for 23 days in the culture medium preparation tank. The liquid culture medium is mixed by stirring and then pumped into a microbial culture tank at a flow rate of 25 L / min controlled by a flow meter.

[0051] The preparation method of the sulfate-reducing bacteria liquid is as follows: 0.1 g of activated freeze-dried bacteria GDMCC 1.537 is dissolved in 0.1 mL of sterile water and inoculated on a blood agar plate, which is cultured at 30°C under anaerobic conditions until colonies grow on the plate. Then, 10 mL of modified Bar sulfate liquid medium (referring to CN 117069275 A) is used for enrichment culture to the logarithmic phase, and the bacterial concentration is adjusted to OD 600 = 2 to obtain the sulfate-reducing bacteria GDMCC 1.537 seed liquid for inoculation.

[0052] In the culture medium preparation tank, the sulfate-reducing bacteria GDMCC 1.537 seed liquid is inoculated at a volume ratio of 5%, and the pH of the microbial culture tank is controlled at 5.5 and the temperature is controlled at 25°C. The top stirring speed is controlled at 100 rpm.

[0053] When the bacterial liquid concentration OD value in the microbial culture tank is 2, the bio-remediation bacterial liquid is obtained.

[0054] Every day, a fixed amount of 20% of the total amount of bio-remediation bacterial liquid with an OD value of at least 2 is pumped into a liquid injection mixing tank at a flow rate of 50 L / min controlled by a flow meter, and finally injected back into the uranium mine underground aquifer pollution area for in-situ microbial remediation of acid leaching of the groundwater in the final mining area.

[0055] Different experimental groups are set according to different addition methods of the organic carbon source.

[0056] Comparative Example 1

[0057] This comparative example is the same as Example 1 except that the addition method of the organic carbon source in the culture medium preparation tank is to add sodium lactate for 45 days.

[0058] Comparative Example 2

[0059] The comparative example is the same as example 1 except that the addition mode of the organic carbon source in the medium preparation tank is to add ethanol for 45 days.

[0060] Comparative example 3

[0061] The comparative example is the same as example 1 except that the addition mode of the organic carbon source in the medium preparation tank is to add ethanol for 22 days first, and then add sodium lactate for 23 days.

[0062] Comparative example 4

[0063] The comparative example is the same as example 1 except that the addition mode of the organic carbon source in the medium preparation tank is to add sodium lactate for 22 days first, and then add ethanol for 23 days.

[0064] Comparative example 5

[0065] The comparative example is the same as example 1 except that the addition mode of the organic carbon source in the medium preparation tank is to add sodium lactate for 15 days first, and then add ethanol for 30 days.

[0066] Comparative example 6

[0067] The comparative example is the same as example 1 except that the addition mode of the organic carbon source in the medium preparation tank is to add sodium lactate for 10 days first, and then add ethanol for 35 days.

[0068] Comparative example 7

[0069] The comparative example is the same as example 1 except that the addition mode of the organic carbon source in the medium preparation tank is to add sodium lactate for 15 days first, and then add Xinjiang sugar beet molasses for 30 days.

[0070] Comparative example 8

[0071] The comparative example is the same as example 1 except that the addition mode of the organic carbon source in the medium preparation tank is to add sodium lactate for 10 days first, and then add Xinjiang sugar beet molasses for 35 days.

[0072] Result detection method:

[0073] Bioremediation bacteria liquid cell dry weight detection method: the bioremediation bacteria liquid is filtered by 0.22 μm filter membrane, dried in 105 ℃ oven, and then cooled. The weight difference between the filter paper before and after drying is the sludge concentration (mlss). The filter paper is placed in a muffle furnace at 500 ℃ for 2 hours, and the weight difference before and after detection is the dry ash content. The cell dry weight is equal to the sludge concentration minus the dry ash, that is, the volatile suspended solid concentration (mlvss) of the bioremediation liquid.

[0074] Daily inoculation amount = cell dry weight concentration of bacteria liquid injected per day × inoculation volume on that day;

[0075] The daily injection amount of 45 days is added to obtain the cumulative injection amount of 45 days.

[0076] The microbial growth amount and carbon source cost under different organic carbon source addition sequences are shown in Table 1. gVSS represents the dry weight (volatile suspended solids, unit g) of the injected bacterial liquid.

[0077] Table 1 Microbial growth amount and carbon source cost under different carbon source addition sequences in continuous perfusion mode with a total bacterial liquid ratio of 20%

[0078]

[0079] The test results of the water quality of the acid-process uranium ore contaminated groundwater before being pumped into the microbial culture tank (under the treatment volume of 1 ton of acid-process uranium ore contaminated groundwater) are shown in Table 2.

[0080] Table 2 Water quality of acid-process uranium ore contaminated groundwater before treatment

[0081] Item pH Uranium concentration (mg / L) Sulfate (mg / L) Iron (mg / L) Nitrate nitrogen (mg / L) Parameter 4.0 0.5 1800 120 49

[0082] The pH of the bioremediation bacterial liquid pumped out after being cultured in the microbial culture tank to an OD value of 2 is increased from 4 to 7. The water quality reaches the Class IV water quality standard (GB / T 14848-2017): the uranium concentration is 0.01 mg / L, the removal rate of iron can reach 98%, the sulfate concentration is 180 mg / L, the removal rate of sulfate can reach 90%, the iron concentration is 0.5 mg / L, the removal rate of iron can reach 99.6%, the nitrate concentration is 0.5 mg / L, and the removal rate of nitrate can reach 99%.

[0083] The carbon source selection results in Example 1 and Comparative Examples 1-8 show that:

[0084] The microbial growth rate using sodium lactate as the organic carbon source is twice that of using ethanol and molasses as the organic carbon source. Initial addition of sodium lactate can effectively improve the early accumulation of sulfate-reducing bacteria and significantly reduce the startup time of sulfate-reducing bacteria expansion. In the later stage, inexpensive organic carbon sources such as ethanol / molasses are used to replace sodium lactate. Although the growth rate of sulfate-reducing bacteria is reduced and the repair startup time is extended, the overall repair cost is reduced.

[0085] When the mode of adding sodium lactate first for 10 days and then adding ethanol for 35 days of Comparative Example 6 is used, the cumulative injection amount of bacteria for 45 days is reduced by 45% and the cost of organic carbon source is reduced by 39% relative to the mode of adding pure sodium lactate of Comparative Example 1; when the mode of adding sodium lactate first for 22 days and then adding ethanol for 23 days of Comparative Example 4 is used, the cumulative injection amount of bacteria for 45 days is reduced by 23% and the cost of organic carbon source is reduced by 25% relative to the mode of adding pure sodium lactate; when the mode of adding sodium lactate first for 15 days and then adding ethanol for 30 days of Comparative Example 5 is used, the cumulative injection amount of bacteria for 45 days is reduced by 35% and the cost of organic carbon source is reduced by 33% relative to the mode of adding pure sodium lactate, but the reduction of the cost of organic carbon source is close to the reduction of the overall injection amount of bacteria; when the cheap organic carbon source is replaced by Xinjiang sugar beet molasses, the amount of microbial growth is basically unchanged, and the cost of organic carbon source is further greatly reduced.

[0086] Example 2

[0087] Except that the proportion of daily extracted bacteria liquid to the total bacteria liquid is different, the remaining steps are the same as those of Example 1.

[0088] During the experiment, 15% of the fixed amount of bioremediation bacteria liquid of the total amount of bioremediation bacteria liquid with an OD value of 2 was extracted daily from the 1st to the 10th day; after 10 days, 25% of the fixed amount of bioremediation bacteria liquid of the total amount of bioremediation bacteria liquid with an OD value of 2 was extracted daily; after 20 days, 15% of the fixed amount of bioremediation bacteria liquid of the total amount of bioremediation bacteria liquid with an OD value of 2 was extracted daily; after 30 days, 25% of the fixed amount of bioremediation bacteria liquid of the total amount of bioremediation bacteria liquid with an OD value of 2 was extracted daily; from the 41st to the 45th day, 15% of the fixed amount of bioremediation bacteria liquid of the total amount of bioremediation bacteria liquid with an OD value of 2 was extracted daily; the flow rate was controlled by a flow meter at 50 L / min, and the pump was pumped into the injection mixing tank, and finally the injection pump was returned to the uranium mine underground aquifer contaminated area for in-situ remediation of acid uranium groundwater.

[0089] Comparative Example 9

[0090] This comparative example is the same as Example 2 except that the addition mode of the organic carbon source in the culture medium preparation tank is to add sodium lactate for 45 days.

[0091] Comparative Example 10

[0092] This comparative example is the same as Example 2 except that the addition mode of the organic carbon source in the culture medium preparation tank is to add ethanol for 45 days.

[0093] Comparative Example 11

[0094] This comparative example is the same as Example 2 except that the addition mode of the organic carbon source in the culture medium preparation tank is to add ethanol for 22 days first and then add sodium lactate for 23 days.

[0095] Comparative Example 12

[0096] The comparative example is the same as Example 2 except that the addition of the organic carbon source in the medium preparation tank is first adding sodium lactate for 22 days, then adding ethanol for 23 days.

[0097] Comparative Example 13

[0098] The comparative example is the same as Example 2 except that the addition of the organic carbon source in the medium preparation tank is first adding sodium lactate for 15 days, then adding ethanol for 30 days.

[0099] Comparative Example 14

[0100] The comparative example is the same as Example 2 except that the addition of the organic carbon source in the medium preparation tank is first adding ethanol for 15 days, then adding sodium lactate for 15 days, and finally adding ethanol for 15 days.

[0101] Comparative Example 15

[0102] The comparative example is the same as Example 2 except that the addition of the organic carbon source in the medium preparation tank is first adding sodium lactate for 15 days, then adding Xinjiang sugar beet molasses for 30 days.

[0103] The microbial growth and the cost of the organic carbon source under different sequences of adding the organic carbon source are shown in Table 3.

[0104] Table 3 Microbial growth and the cost of the organic carbon source under different sequences of adding the organic carbon source in the total bacterial liquid ratio of 15%-25% and alternating every 10 days

[0105]

[0106] The results of the selection of the organic carbon source in Examples 1 and 2 and Comparative Examples 1-15 are as follows:

[0107] The test results of the water quality of the acid uranium ore contaminated groundwater before being pumped into the microbial culture tank (under the treatment volume of 1 ton of acid uranium ore contaminated groundwater) are shown in Table 2:

[0108] The water quality of the acid uranium ore contaminated groundwater before being treated is shown in Table 4:

[0109] Table 4 Water quality of the acid uranium ore contaminated groundwater before being treated

[0110] Item pH Uranium concentration (mg / L) Sulfate (mg / L) Iron (mg / L) Nitrate nitrogen (mg / L) Parameter 4.0 0.5 1800 120 49

[0111] The pH of the bioremediation bacteria liquid pumped out when the OD value of the bacteria liquid concentration is 2 after the above microbial culture tank cultivation is increased from 4 to 7; the water quality reaches the groundwater quality standard IV water quality standard (GB / T 14848-2017): the uranium concentration is 0.01 mg / L, the removal rate of iron can reach 98%, the sulfate concentration is 180 mg / L, the removal rate of sulfate can reach 90%, the iron concentration is 0.5 mg / L, the removal rate of iron can reach 99.6%, and the nitrate concentration is 0.5 mg / L, and the removal rate of nitrate can reach 99%.

[0112] The proportion of the extracted bacteria liquid to the total bacteria liquid in the culture tank is adjusted from 20% to 15%-25% extraction and injection alternation every 10 days, which can effectively alleviate the accumulation of hydrogen sulfide, and the actual value of hydrogen sulfide is stabilized at 50-95 mg / L, effectively alleviating the problem of hydrogen sulfide accumulation inhibiting microbial growth, while the substrate utilization rate of the bioremediation bacteria liquid and the microbial propagation amount are increased, which can increase the effective concentration of the bioremediation bacteria liquid in the culture tank, and the total amount of injected bacteria is increased as a whole within 45 days. Although the sludge concentration will increase significantly in long-term 15% extraction, hydrogen sulfide will accumulate in large amounts, which will inhibit growth, so it needs to be combined with 25% alternate extraction and injection. Compared with the mode of first adding sodium lactate and then adding ethanol, the mode of first adding sodium lactate and then adding Xinjiang sugar beet molasses can achieve greater microbial growth amount at the same cost of organic carbon source.

[0113] In summary, the mode of first adding sodium lactate and then adding Xinjiang sugar beet molasses can effectively improve the starting speed of GDMCC1.537 strain and reduce the cost of organic carbon source, and the microbial starting speed is further improved when the proportion of daily extracted bacteria liquid to total bacteria liquid in the culture tank is adjusted from 20% to 15%-25% extraction and injection alternation every 10 days. The maximum amount of biomass injection within 45 days is achieved when the extraction and injection alternation is 15%-25% every 10 days.

[0114] At the same time, the contaminated raw water in the uranium ore-containing aquifer leached by acid method is used as the main part of the liquid culture medium, and the cheap organic carbon source is replaced, and through reasonable extraction and injection ratio of bioremediation bacteria liquid, in-situ sustainable and economic and efficient bioremediation can be realized, and the cost of in-situ groundwater bioremediation is reduced.

[0115] Although the above embodiments have made a detailed description of the present application, it is only a part of the embodiments of the present application, not all the embodiments, and other embodiments can be obtained according to the present embodiments without creativity, which belong to the protection scope of the present application.

Claims

1. A bioremediation method for treating acid leach uranium groundwater, characterised in that, The method comprises the following steps: (1) extracting acid leaching uranium groundwater from an acid leaching uranium ore containing aquifer, and obtaining treated acid leaching uranium groundwater after filtration and pH adjustment; the pH value is 3-4; (2) mixing the treated acid leaching uranium groundwater with a nitrogen source, potassium dihydrogen phosphate, and adding an organic carbon source to obtain a liquid culture medium; the liquid culture medium contains sulfate, uranium and iron ions; (3) inoculating sulfate-reducing bacteria in the liquid culture medium, and expanding the culture to an OD value of at least 2 to obtain a biological remediation bacterial solution; the volume ratio of the seed liquid of the sulfate-reducing bacteria to the liquid culture medium is 0.5%-5%; the sulfate-reducing bacteria are GDMCC 1.537 strains; (4) injecting a fixed amount of biological remediation bacterial solution of 15% or 25% of the total volume of the biological remediation bacterial solution into the acid leaching final mining area groundwater to carry out in-situ microbial remediation every day; a fixed amount of biological remediation bacterial solution of 15% or 25% of the total volume of the biological remediation bacterial solution is extracted every day, and the volume ratio of the biological remediation bacterial solution extracted alternately is 15% and 25% with an interval of 10 days; the remediation time is 45 days; The organic carbon source is added in the form of sodium lactate for 22 days and then molasses for 23 days.

2. The method of claim 1, wherein, The filtration uses a filter bag with a pore size of 5-20 µm to trap large particles in the groundwater.

3. The method of claim 1, wherein, The concentration of sulfate in the liquid culture medium is 900-2500 mg / L, the concentration of uranium is 0.1-0.5 mg / L, and the concentration of iron ions is 50-150 mg / L.

4. The method of claim 1, wherein, The expansion culture conditions in step (3) are to control the culture pH to be 5.0-5.5 and the temperature to be 20-25°C.

5. The method of claim 1, wherein, After adding the organic carbon source in step (3), the weight ratio of the treated acid leaching uranium groundwater, the organic carbon source, the nitrogen source, and the potassium dihydrogen phosphate is 10000:10-20:0.5-2:0.1-0.

2.

6. The method of claim 1, wherein, The remediation is carried out in a continuous culture injection and extraction system, and the system comprises a submersible pump, a flow meter, a filter, a buffer adjustment tank, a transfer pump, a culture medium ingredient tank, a microbial culture tank, and a liquid injection mixing tank.

Images