An emulsified oil, a method for producing the same, and use thereof

Abstract

The present application relates to a kind of emulsified oil and its preparation method and application, and the raw materials of emulsified oil include: carbon source, surfactant and water, carbon source includes high carbon alcohol and soybean oil mixture or biodiesel.The emulsified oil of the present application includes high carbon alcohol and biodiesel, high carbon alcohol is mainly composed of C16 fatty alcohol, fatty alcohol oxidation degradation process will form dicarboxylic acid, and dicarboxylic acid can be oxidized from both ends, greatly speed up the speed of high carbon alcohol degradation into a variety of fatty acid intermediates, in addition, biodiesel contains a large number of straight-chain fatty acids, under the action of microorganism, straight-chain fatty acids are rapidly degraded into a variety of fatty acid intermediates.Fatty acid intermediates can effectively provide nutrition for the growth of SRB, stimulate the growth of SRB, so as to promote the reduction of sulfate ion in AMD into sulfur ion, so that heavy metal in AMD and sulfur ion generate sulfide precipitate removal, thereby improving the operation efficiency of PRB.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to an emulsified oil, its preparation method, and its application. Background Technology

[0002] During mining activities or tailings disposal, sulfide minerals, primarily pyrite (FeS2), in the ore and tailings are exposed on the surface. Through natural weathering and biochemical oxidation, large amounts of acidic mine wastewater (AMD) are generated. AMD typically has a pH below 3. This low pH causes a large amount of heavy metal ions from the wastewater to dissolve, resulting in a certain concentration of toxic and harmful heavy metal ions in the water, which often causes very serious harm to the receiving terrestrial or aquatic ecosystems.

[0003] Bioreactive barrier (PRB) technology can remediate AMD (Advanced Microorganisms). PRB involves creating an activated material engineering zone along the flow path of groundwater. When contaminated groundwater comes into contact with the activated material, a reaction occurs, removing the pollutants. PRB typically adds sulfate-reducing bacteria (SRB) to the PRB column. Under anaerobic conditions, SRB use organic matter in the wastewater as a carbon source and, through its own dissimilatory reduction, converts sulfate ions into sulfide ions. This allows metal ions in AMD to precipitate and be removed.

[0004] Solid materials (including straw, fertilizer, sawdust, etc.) are typically added to PRB columns as long-lasting nutrients to provide sufficient carbon sources and ensure the long-term growth of SRB. However, because solid materials such as sawdust have relatively poor degradation properties, using these solid materials means a lower sulfate reduction rate. Furthermore, the relatively easily degradable parts of the organic matrix of solid materials (such as cellulose) decompose rapidly, leaving behind lignin, which has some resistance to microbial degradation. This significantly reduces the operating efficiency of PRBs. Summary of the Invention

[0005] Therefore, it is necessary to provide an emulsified oil that addresses the technical problem of low operating efficiency when solid materials are added to PRB columns in the prior art.

[0006] To achieve the above objectives, the present invention provides a technical solution:

[0007] An emulsified oil, wherein the raw materials for preparing the emulsified oil include: a carbon source, a surfactant, and water;

[0008] The carbon source includes a mixture of higher alcohols and soybean oil or biodiesel.

[0009] Preferably, the carbon source in the emulsified oil accounts for ≥8% by mass.

[0010] Preferably, the surfactant includes at least one of lecithin and Tween 80.

[0011] The present invention also provides a method for preparing an emulsified oil as described in any one of the above claims, wherein the method for preparing the emulsified oil includes the following steps:

[0012] The emulsified oil is obtained by mixing the carbon source, the surfactant, and the water evenly.

[0013] Preferably, the specific steps of uniformly mixing the carbon source, the surfactant, and the water include:

[0014] The carbon source, the surfactant, and the water are stirred and mixed to obtain a mixture;

[0015] The mixture is centrifuged, and the stability value of the mixture is determined by reading the amount of oil separated by centrifugation.

[0016] When the mixture separates out oil, the mixture has not reached the preset stability value. Continue stirring the mixture and centrifuge it to determine the stability value of the mixture again.

[0017] The mixture reaches a preset stability value when no more oil separates from it, thus obtaining the emulsified oil.

[0018] Preferably, in the step of centrifuging the mixture, the centrifugation speed is 3000-5000 r / min.

[0019] Preferably, in the step of centrifuging the mixture, the centrifugation time is 5 to 10 minutes.

[0020] The present invention also provides the application of the emulsified oil as described in any of the above claims in the repair of AMD.

[0021] Preferably, the application method includes:

[0022] The emulsified oil was added to the PRB column to repair AMD.

[0023] Preferably, the emulsified oil accounts for 1%-5% of the total mass of the PRB filler.

[0024] The beneficial effects of this invention are:

[0025] The emulsified oil of this invention includes higher alcohols and biodiesel. The higher alcohols are mainly composed of C16 fatty alcohols. During the oxidative degradation of fatty alcohols, dicarboxylic acids are formed. These dicarboxylic acids can undergo β-oxidation at both ends, greatly accelerating the degradation of higher alcohols into various fatty acid intermediates. Furthermore, biodiesel contains a large amount of straight-chain fatty acids, which are rapidly degraded into various fatty acid intermediates under the action of microorganisms. These fatty acid intermediates effectively provide nutrients for the growth of SRB (sulfuric acid biodiesel), stimulating SRB growth and promoting the reduction of sulfate ions to sulfide ions in AMD (adverse metallurgical processes). This allows heavy metals in AMD to react with sulfide ions to form sulfide precipitates for removal, thereby improving the operating efficiency of the PRB (probiotic biodiesel). Detailed Implementation

[0026] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0027] In the embodiments, unless otherwise specified, the experimental methods used are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0028] An emulsified oil, the raw materials for preparing the emulsified oil include: a carbon source, a surfactant, and water;

[0029] The carbon sources include mixtures of higher alcohols and soybean oil or biodiesel.

[0030] The emulsified oil of this invention includes higher alcohols and biodiesel. The higher alcohols are mainly composed of C16 fatty alcohols. During the oxidative degradation of fatty alcohols, dicarboxylic acids are formed. These dicarboxylic acids can undergo β-oxidation at both ends, greatly accelerating the degradation of higher alcohols into various fatty acid intermediates. Furthermore, biodiesel contains a large amount of straight-chain fatty acids, which are rapidly degraded into various fatty acid intermediates under the action of microorganisms. These fatty acid intermediates effectively provide nutrients for the growth of SRBs, stimulating their growth and promoting the reduction of sulfate ions to sulfide ions in AMDs. This allows heavy metals in AMDs to react with sulfide ions to form sulfide precipitates for removal, thereby improving the operating efficiency of PRBs. In addition, the emulsified oil has the characteristics of slow electron release and low permeation loss after injection into the aqueous layer; therefore, the emulsified oil has high stability.

[0031] In one embodiment, the carbon source in the emulsified oil accounts for ≥8% by mass.

[0032] In one embodiment, the mass ratio of carbon source, surfactant and water is preferably 10:2:88.

[0033] In one embodiment, the mass ratio of higher alcohols, soybean oil, surfactants and water is preferably 8:2:2:88.

[0034] Specifically, since the surfactant (lecithin) has low solubility in higher alcohols, it is necessary to mix the higher alcohols and soybean oil before using them to prepare emulsified oil.

[0035] Specifically, deionized water is preferred for preparing emulsified oil to reduce the influence of other factors.

[0036] In one embodiment, the surfactant includes at least one of lecithin and Tween 80. Specifically, lecithin and Tween 80 can be used as surfactants, and N-sources and P-sources can also be provided on the other hand.

[0037] The present invention also provides a method for preparing an emulsified oil as described in any one of the above claims, wherein the method for preparing the emulsified oil includes the following steps:

[0038] Emulsified oil is obtained by mixing carbon source, surfactant and water evenly.

[0039] In one embodiment, the specific steps of uniformly mixing the carbon source, surfactant, and water include:

[0040] S100. Mix the carbon source, surfactant and water to obtain a mixture;

[0041] S200. The mixture is centrifuged, and the stability value of the mixture is determined by reading the amount of oil separated by centrifugation.

[0042] Specifically, the specific method for centrifugation is as follows:

[0043] Transfer the mixture into 10 mL centrifuge tubes and place them in a centrifuge. Centrifuge at a speed of 3000–5000 r / min for 5–10 min.

[0044] When the mixture separates into oil, the mixture has not reached the preset stability value. Continue stirring the mixture and centrifuge it to determine the stability value of the mixture again.

[0045] When no more oil separates from the mixture, the mixture reaches the preset stability value, thus obtaining emulsified oil.

[0046] The present invention also provides the application of the emulsified oil as described in any of the above claims in the repair of AMD.

[0047] In one embodiment, the application method includes:

[0048] Emulsified oil is added to the PRB column to repair AMD; specifically, the emulsified oil accounts for 1%-5% of the total mass of the PRB packing.

[0049] Example 1

[0050] S100. Mix the higher alcohol, soybean oil, lecithin and deionized water at a mass ratio of 8:2:2:88 at high speed until homogeneous to obtain a mixture;

[0051] S200. Transfer the mixture into a 10mL centrifuge tube and place it in a centrifuge. Centrifuge at 3000r / min for 5min.

[0052] When the mixture separates into oil, the mixture has not reached the preset stability value. Continue stirring the mixture and centrifuge it to determine the stability value of the mixture again.

[0053] When no more oil separates from the mixture, the mixture reaches the preset stability value, thus obtaining emulsified oil 1.

[0054] Example 2

[0055] In Example 1, the higher alcohols and soybean oil were replaced with biodiesel, while all other ingredients remained unchanged, to obtain emulsified oil 2.

[0056] Comparative Example 1

[0057] In Example 1, the higher alcohols and soybean oil were replaced with pure soybean oil, while all other ingredients remained unchanged, to obtain emulsified oil 3.

[0058] To evaluate the effectiveness of emulsified oil in repairing AMD, the following tests were conducted:

[0059] (1) Preparation of sulfate solution

[0060] Anhydrous sodium sulfate (AR) was used to prepare a sulfate solution with a concentration of 1500 mg / L to simulate the high sulfate concentration in AMD. To simplify the chemical system and avoid uncontrolled precipitation of sulfides, the simulation solution contained no dissolved heavy metals.

[0061] (2) A simulated column experiment was conducted in an acrylic glass column (PRB column). The emulsified oil 1 obtained in Example 1 was added to the PRB column. The emulsified oil accounted for 1% of the total volume of the PRB packing. Specifically, the PRB packing included quartz sand (44%), limestone (5%), peat moss (30%), sawdust (20%), and bacterial source (1%). All percentages are by volume. The bacterial source was a mixture of anaerobic sludge from a domestic sewage treatment plant and bottom mud from a mining site pond, with a mass ratio of 1:1. The bacterial source was added when assembling the column packing. The main bacterial groups of the bacterial source were tested and are shown in Tables 2, 3, and 4.

[0062] (3) Using a variable speed multichannel pump (ISMATEC), the simulated liquid from step (1) was delivered from the bottom to each PRB column at an average flow rate of 0.005 mL / min. Based on the measured column area and average packing porosity (0.19), the flow rate was calculated to be equal to a flux rate of 5.26 cm / d (average residence time of 4.7 days).

[0063] (4) Take a sample and analyze it every 50 mL of leachate that flows out of the PRB column outlet.

[0064] A control group was set up in which emulsified oil 1 was not added to the organic column in step (2), and the other steps were the same as those in steps (1), (2), (3), and (4) above.

[0065] Set up a comparison group 1, and replace the emulsified oil 1 in step (2) with the emulsified oil 2 prepared in Example 2. Other steps are the same as steps (1), (2), (3), and (4) above.

[0066] Set up a comparison group 2, and replace the emulsified oil 1 in step (2) with the emulsified oil 3 prepared in comparison example 1. Other steps are the same as steps (1), (2), (3), and (4) above.

[0067] The specific analysis items are as follows:

[0068] A. The pH and total water-soluble salt (EC) of the leachate from the addition of emulsified oil 1, emulsified oil 2, emulsified oil 3 and the control group were measured.

[0069] B. The dissolved oxygen (DO) and oxidation-reduction potential (Eh) of rapidly consumed water in the leachates of the added emulsified oil 1, emulsified oil 2, emulsified oil 3 and the control group were measured. When DO and Eh decreased and the leachate was in a reducing state, it indicated that the emulsified oil prepared by the present invention successfully promoted the growth of reducing microorganisms such as SRB.

[0070] C. The concentration of sulfate ions in the leachates of the added emulsified oil 1, emulsified oil 2, emulsified oil 3, and the control group was measured. The concentration of sulfate ions was significantly reduced, indicating that the AMD treatment was successful.

[0071] D. The relative abundance of bacteria in PRB columns containing emulsified oil 1, emulsified oil 2, emulsified oil 3, and the control group was measured.

[0072] The measurement results of pH, EC, DO, Eh and sulfate ion concentrations are shown in Table 1.

[0073] The results of the measurement of the relative abundance of bacteria at the phylum level are shown in Table 2.

[0074] The results of the relative abundance measurement of bacteria at the genus level are shown in Table 3.

[0075] The results of the relative abundance measurements of bacteria at the class level are shown in Table 4.

[0076] Table 1. Measurement results of pH, EC, DO, Eh and sulfate ion concentrations

[0077]

[0078]

[0079] Table 2 shows the measurement results of the relative abundance of bacteria at the phylum level (major bacterial groups).

[0080]

[0081] Table 3 shows the measurement results of the relative abundance of bacteria at the genus level (major bacterial groups).

[0082]

[0083]

[0084] Table 4 shows the measurement results of the relative abundance of bacteria at the class level (major bacterial groups).

[0085]

[0086] As shown in Table 1, compared with the control group, the emulsified oil prepared in Example 1 with added higher alcohols can continuously provide carbon and energy sources for the growth of sulfate-reducing bacteria, effectively reducing DO and Eh in the effluent. The sulfate concentration reached its lowest point during the fourth sampling, with a corresponding average sulfate removal rate of 88.0%. Emulsified oil 1 with added higher alcohols showed better sulfate removal performance than emulsified oil 2 with added biodiesel, with an average sulfate removal rate of 85.5% for emulsified oil 2.

[0087] Emulsified oil 1 and emulsified oil 2 are superior to traditional emulsified oil 3 with added soybean oil, with emulsified oil 3 showing an average sulfate removal rate of 71.7%.

[0088] Emulsified oils derived from higher alcohols and biodiesel offer a more suitable C / N ratio for SRB growth, and fatty alcohols themselves consume more DO during the oxidation phase, which may contribute to the formation of a reducing environment. Furthermore, higher alcohols are mainly composed of C16 fatty alcohols, which have short C chains and are easily degraded and utilized. The degradation of fatty alcohols leads to the formation of dicarboxylic acids. These dicarboxylic acids can undergo β-oxidation from both ends, which will greatly accelerate the degradation into various fatty acid intermediates.

[0089] Tables 2-4 show that, compared with the control group, the addition of emulsified oil significantly increased the richness and diversity of the microbial community. It promoted the growth of *Desulfovibrio* and some organic-degrading bacteria such as *Clostridium sensustricto* and *Bacteroidales*, enhancing the treatment effect of biological PRB. Compared with the control group, the relative abundance of *Desulfovibrio* in emulsified oil 1 with added higher alcohols was lower than that in emulsified oil 3 with added soybean oil. This is because emulsified oil 1 with added higher alcohols has a faster sulfate reduction rate, and the accumulation of reduction products inhibited the later growth of *Desulfovibrio*.

[0090] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural transformations made using the present invention's specification under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. Use of an emulsified oil for the repair of AMD, characterized in that, The preparation raw material of the emulsified oil comprises a carbon source, a surfactant and water. The carbon source comprises a mixture of a high-carbon alcohol and soybean oil, and the high-carbon alcohol is a C16 fatty alcohol. The mass percentage of the carbon source in the emulsified oil is greater than or equal to 8%.

2. Use according to claim 1, characterized in that, The surfactant comprises at least one of lecithin and Tween 80.

3. Use according to claim 1, characterized in that, The preparation method of the emulsified oil comprises the following steps: The carbon source, the surfactant and the water are mixed uniformly to obtain the emulsified oil.

4. Use according to claim 3, characterized in that, The specific steps of mixing the carbon source, the surfactant and the water uniformly comprise the following steps: The carbon source, the surfactant and the water are stirred and mixed to obtain a mixed solution; The stability value of the mixed solution is determined by reading the oil amount separated from the mixed solution by centrifugation; When the mixed solution separates out oil, the mixed solution does not reach the preset stability value, the mixed solution is continuously stirred, and the mixed solution after stirring is subjected to centrifugation treatment, and the stability value of the mixed solution is determined again; Until the mixed solution does not separate out oil, the mixed solution reaches the preset stability value, and the emulsified oil is obtained.

5. Use according to claim 4, characterized in that, In the step of centrifuging the mixed solution, the speed of centrifugation is 3000-5000 r / min.

6. Use according to claim 4, characterized in that, In the step of centrifuging the mixed solution, the centrifugation time is 5-10 min.

7. The use according to claim 1, characterized in that, The application method comprises the following steps: The emulsified oil is added to a PRB column to repair AMD.

8. Use according to claim 7, characterized in that, The emulsified oil accounts for 1%-5% of the total mass of the PRB filler.

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