Composite adsorption material as well as preparation method and application thereof

Abstract

The composite adsorption material comprises a microbial flocculant and modified fly ash, and the mass ratio of the microbial flocculant to the modified fly ash is 0.1-0.5; the microbial flocculant is obtained by separating and drying a fermentation liquid of bacillus parabarisiformis; the modified fly ash is fly ash modified by candelilla wax. The composite adsorption material is used for treating the fracturing flow-back fluid, has high suspended matter removal rate (80%-96%) and oil removal rate (65%-95%), and does not cause secondary pollution to the environment. The system is remarkable in application effect and easy to operate, and has a good application prospect in the aspect of flocculation treatment of the oil field fracturing flow-back fluid.

Description

Technical Field

[0001] The invention relates to a composite adsorption material and a preparation method thereof and application of the composite adsorption material in fracturing flowback fluid treatment, belonging to the field of liquid waste treatment materials. Background Art

[0002] Oilfield fracturing flowback fluid has the characteristics of high COD, high SS, high oil content, high salinity, high stability, complex pollutant composition and difficulty in treatment. If it is discharged without treatment, it will have a serious impact on the ecosystem, such as polluting surface water and groundwater, causing eutrophication of water bodies, and endangering ecological safety and human health.

[0003] It is an economical and reasonable way to treat the fracturing flowback fluid and reuse it as the base fluid for preparing fracturing fluid. From the perspective of low-carbon, green and sustainable development, treating the fracturing flowback fluid and reusing it in the preparation of fracturing fluid is of great significance for reducing the total amount of sewage, lowering operating costs and alleviating environmental hazards.

[0004] Compared with physical and chemical methods for treating fracturing flowback fluid, biological methods are environmentally friendly, free of secondary pollution, low in cost and good in treatment effect. It is usually difficult to remove organic matter and suspended particles in fracturing flowback fluid at the same time with a single treatment method. Therefore, the combined treatment of fracturing flowback fluid with microbial flocculation and adsorption materials is a promising method.

[0005] There are few studies on the use of combined microbial flocculation and adsorption materials to treat fracturing flowback fluids, especially the application of candelilla wax-modified fly ash in the treatment of fracturing flowback fluids.

[0006] CN112897787A discloses a method for treating shale gas fracturing return water, which sequentially performs coagulation precipitation, chemical precipitation, oxidation and four-effect evaporation treatment on the shale gas fracturing return water, and the conventional indicators in the fracturing return water after treatment can reach the first-level standard of the comprehensive sewage discharge standard. The process flow of the method is relatively complicated.

[0007] CN112744910A discloses a method for using shale gas return water sediment microorganisms to reduce shale gas return water organic matter at low cost and high efficiency, including the following steps: collecting the sludge accumulated at the bottom of the shale gas return water storage tank for a long time; inoculating the sludge into the anoxic or anaerobic storage tank of the shale gas return water to be treated, turning on the stirring device, and treating for a period of time, the volume ratio of the sludge to the return water to be treated is 1:1 to 2:3. This method directly utilizes the microorganisms in the sediment of the return water, without adding any chemicals and other microorganisms, and can efficiently remove organic pollutants in the return water, while reducing the environmental risks of the sediment of the return water. However, the method is time-consuming.

[0008] CN1566000A discloses a method for treating the backflow wastewater produced by fracturing construction. Coagulation treatment is used to improve the treatment efficiency, internal electrolysis can improve the biodegradability of wastewater and remove metal ions, adsorption method is used to shorten the biochemical treatment time, and the use of cultivated and domesticated microbial flora can improve the sewage treatment efficiency. The above methods are used in sequence to achieve sewage discharge that meets the standards.

[0009] CN115893711A discloses a method for treating organic sulfur in fracturing flowback fluid in oil and gas fields. First, a chelating agent and an alkali solution are added to the fracturing flowback fluid to chemically absorb the organic sulfur. Then, a modified nano-catalyst is added to catalytically oxidize the organic sulfur and regenerate the alkali solution. Then, a biomass desulfurizer is used to reabsorb the residual organic sulfur. Finally, fine filtration is performed to obtain the treated fracturing flowback fluid, which effectively solves the problem of foul odor emitted by fracturing flowback water on site in oil and gas fields. Summary of the invention

[0010] The physical and chemical methods have the problems of high cost, secondary pollution to the environment, and the difficulty of removing suspended matter and petroleum organic matter in fracturing return fluid by a single treatment method.

[0011] A composite adsorption material comprises a microbial flocculant and modified fly ash, wherein the mass ratio of the microbial flocculant to the modified fly ash is 0.1-0.5; the microbial flocculant is obtained by separating and drying the fermentation liquid of Bacillus paramycoides; and the modified fly ash is fly ash modified with candelilla wax.

[0012] The particle size of the composite adsorption material is 10-500 μm, more preferably 50-200 μm.

[0013] The composite adsorption material has a suspended matter removal rate of 80%-96% and a crude oil adsorption rate of 65%-95% for fracturing return fluid.

[0014] The preparation method of the microbial flocculant comprises the following steps:

[0015] The paramycoides selected from the fracturing flowback fluid is activated and inoculated into a fermentation medium for cultivation. The obtained fermentation liquid is centrifuged at low temperature to obtain a supernatant, which is then separated by alcohol precipitation and frozen to obtain a precipitate, which is then dried to obtain a microbial flocculant powder.

[0016] The culture medium composition is: 5-20g·L -1 Glucose, 5-10 g L -1 (NH4)2SO4, 1-5g·L -1 KH2PO4, 1-10g·L -1K2HPO4; culture temperature 25-35℃, volume ratio of bacterial liquid to culture medium 0.001-0.01, fermentation time 24-48h, pH 9-11, ultrasonic stirring 1-30min, microbial flocculant production reached 5-10g·L -1 .

[0017] The culture time is 1-7 days, more preferably 2-3 days; the low-temperature centrifugal separation is carried out at a temperature of 2-6°C, a rotation speed of 5000-10000 rpm, and a time of 10-60 minutes; more preferably, the temperature is 3-5°C, the rotation speed is 6000-8000 rpm, and the time is 15-30 minutes.

[0018] The alcohol used in the alcohol precipitation is methanol or ethanol, and the amount of alcohol added in the alcohol precipitation is 1-5 times the amount of the supernatant, preferably 2-3 times; the freezing separation temperature is -10°C to -30°C, more preferably -15°C to -25°C; the alcohol precipitation time is 12-48h, more preferably 12-36h; the drying is carried out under freezing conditions, the temperature is -50 to -80°C, and the time is 12-48h.

[0019] The preparation method of the modified fly ash comprises the following steps:

[0020] The candelilla wax is heated and dissolved in an organic solvent, fly ash is added for impregnation and stirring, and the impregnated fly ash is separated and dried to obtain modified fly ash.

[0021] The organic solvent is anhydrous ethanol or anhydrous propanol, the heating temperature is 50°C-70°C, the mass ratio of the organic solvent to the candelilla wax is 5-20, more preferably 10-15; preferably, the fly ash is fly ash floating beads, the sintering temperature of the fly ash floating beads is 1000°C-1200°C, the particle size of the fly ash floating beads is 1-300 μm, more preferably 30-100 μm, and the specific surface area is 300-360 cm 2 / g; the volume ratio of the organic solvent to the fly ash is 1-5, more preferably 2-3; the drying temperature is 50℃-70℃, more preferably 50℃-60℃.

[0022] A method for preparing a microbial flocculant-modified fly ash composite adsorption material comprises the following steps:

[0023] The microbial flocculant is dissolved in a solvent, added into the modified fly ash and immersed for 24-72 hours, filtered and then freeze-dried to obtain a microbial flocculant-modified fly ash composite adsorption material.

[0024] The solvent is one of ethanol, glycerol, propanol and ethylene glycol; the immersion is carried out under ultrasonic conditions; the freeze-drying temperature is -40°C to -60°C, and the freeze-drying time is 24-48 hours.

[0025] A microbial flocculant-modified fly ash composite adsorption material is used for fracturing fluid flowback treatment, wherein the amount of the composite adsorption material is 100-500 g / t, more preferably 200-300 g / t.

[0026] The concentration of suspended matter in the fracturing fluid return fluid is 100-1000 mg / L, more preferably greater than 300-800 mg / L; the concentration of petroleum organic matter is 50-800 mg / L, more preferably 200-750 mg / L; the composite adsorption material is added to the fracturing return fluid and stirred for 5-30 minutes, preferably, heated to 20°C-30°C.

[0027] The beneficial technical effect of the present invention is that the composite adsorption material is used to treat fracturing flowback fluid, which has a high suspended matter removal rate (80%-96%) and oil reduction rate (65%-95%), and does not cause secondary pollution to the environment. The system has significant application effect and is easy to operate, and has good application prospects in the flocculation treatment of fracturing flowback fluid in oil fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of combined treatment of fracturing flowback fluid;

[0029] Figure 2 is the removal efficiency of suspended solids by different adsorbents and their concentration after treatment;

[0030] Figure 3 Removal efficiency and post-treatment concentration of petroleum pollutants by different adsorbents. DETAILED DESCRIPTION

[0031] The technical solutions and applications of the present invention are described clearly and completely below through various embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] A composite adsorption material comprises a microbial flocculant and modified fly ash, wherein the mass ratio of the microbial flocculant to the modified fly ash is 0.2; the microbial flocculant is obtained by separating and drying the fermentation liquid of Bacillus paramycoides; and the modified fly ash is fly ash modified with candelilla wax.

[0034] The preparation method of the microbial flocculant (MBF) comprises the following steps:

[0035] The paramycoides selected from the fracturing flowback fluid is activated and inoculated into a fermentation medium for cultivation. The obtained fermentation liquid is centrifuged at low temperature to obtain a supernatant, which is then separated by alcohol precipitation and freezing to obtain a precipitate, which is then dried to obtain a microbial flocculant powder (MBF).

[0036] The culture medium composition was 10 g·L -1 Glucose, 3.6 g L -1 (NH4)2SO4, 2g·L -1 KH2PO4, 5 g·L - 1 K2HPO4; fermentation temperature 30℃, bacterial inoculum volume 1mL, fermentation time 36h, by adjusting the pH value of the fermentation broth, and heating and ultrasound (pH 9-11, heating temperature 30℃, ultrasound time 4min), MBF production reached 5-5.8g·L -1 The culture time is 3 days; the low-temperature centrifugation separation temperature is 5°C, the rotation speed is 6000 rpm, and the time is 15 minutes.

[0037] Ethanol is used in the alcohol precipitation, and the amount of alcohol added in the alcohol precipitation is 3 times the amount of the supernatant; the freezing separation temperature is -15°C; the alcohol precipitation time is 12h; the drying is carried out under freezing conditions, the temperature is -50°C, and the time is 12h.

[0038] The preparation method of the modified fly ash comprises the following steps:

[0039] Dissolve the candelilla wax in anhydrous propanol and heat to 50°C, add fly ash beads and immerse and stir, the mass ratio of organic solvent to candelilla wax is 10, the particle size of fly ash beads is 30-100μm, and the specific surface area is 300-360cm 2 / g, the impregnated fly ash was separated and dried in an oven at 60°C for 12h to obtain candelilla wax modified fly ash floating beads (CF).

[0040] The microbial flocculant is dissolved in a solvent, added to the modified fly ash and impregnated for 24-72 hours, filtered and freeze-dried to obtain a microbial flocculant-modified fly ash composite adsorption material (i.e., MBF+CF). The solvent is ethanol; the impregnation is performed under ultrasonic conditions; the freeze-drying temperature is -40°C and the freeze-drying time is 24-48 hours.

[0041] Comparative Example 1

[0042] The other steps are the same as in Example 1, except that only microbial flocculant (MBF) is used.

[0043] Comparative Example 2

[0044] The other parts are the same as Example 1, except that only modified fly ash (CF) is used.

[0045] The adsorption treatment agent of Example 1 and Comparative Examples 1-2 was used to treat the oil well fracturing flowback fluid, wherein the concentration of suspended matter in the fracturing flowback fluid was 671 mg / L; the concentration of petroleum organic matter was 752 mg / L; the adsorption treatment agent was added to the fracturing flowback fluid at an amount of 300 g / t, stirred for 30 minutes, heated to 30°C, and allowed to stand for stratification. The results are as follows Figure 2 and 3 As shown, KB is the return liquid without adding any flocculant, and only static stratification treatment is performed; MBF is a comparative example in which only microbial flocculant is added; CF is a comparative example in which only modified fly ash is added; MBF+CF is the composite adsorption material obtained in Example 1.

[0046] The present invention has been described in detail by general description and specific embodiments, but it is obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, these modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A composite adsorption material, comprising a microbial flocculant and modified fly ash, wherein the mass ratio of the microbial flocculant to the modified fly ash is 0.1-0.5; the microbial flocculant is obtained by separating and drying the fermentation liquid of Bacillus paramycoides; and the modified fly ash is fly ash modified with candelilla wax.

2. The composite adsorption material according to claim 1, characterized in that The particle size of the composite adsorption material is 10-500 μm, more preferably 50-200 μm.

3. The composite adsorption material according to claim 1, characterized in that The composite adsorption material has a suspended matter removal rate of 80%-96% and an oil removal rate of 65%-95% for fracturing flowback fluid.

4. The composite adsorption material according to claim 1, characterized in that The preparation method of the microbial flocculant comprises the following steps: activating the Bacillus paramycoides screened from the fracturing flowback fluid and inoculating it into a fermentation medium for cultivation; subjecting the obtained fermentation liquid to low-temperature centrifugal separation to obtain a supernatant; and then subjecting it to alcohol precipitation and freezing to separate a precipitate and drying it to obtain a microbial flocculant powder.

5. The composite adsorption material according to claim 4, characterized in that The culture medium composition is: 5-20g·L -1 Glucose, 5-10 g L -1 (NH4)2SO4, 1-5g·L -1 KH2PO4, 1-10g·L -1 K2HPO4; culture temperature 25℃-35℃, volume ratio of bacterial liquid to culture medium 0.001-0.01, fermentation time 24-48h, pH value 9-11, ultrasonic stirring 1-30min, microbial flocculant production reaches 5-10g·L -1 ; The culture time is 1-7 days, more preferably 2-3 days; the low-temperature centrifugation separation is carried out at a temperature of 2°C-6°C, a rotation speed of 5000-10000 rpm, and a time of 10-60 minutes; more preferably, the temperature is 3°C-5°C, the rotation speed is 6000-8000 rpm, and the time is 15-30 minutes.

6. The composite adsorption material according to claim 4, characterized in that The alcohol used in the alcohol precipitation is methanol or ethanol, and the amount of alcohol added in the alcohol precipitation is 1-5 times the amount of the supernatant, preferably 2-3 times; the freezing separation temperature is -10°C to -30°C, more preferably -15°C to -25°C; the alcohol precipitation time is 12-48h, more preferably 12-36h; the drying is carried out under freezing conditions, the temperature is -50°C to -80°C, and the time is 12-48h.

7. The composite adsorption material according to claim 1, characterized in that The preparation method of the modified fly ash comprises the following steps: heating candelilla wax to dissolve in an organic solvent, adding fly ash to impregnate and stir, separating the impregnated fly ash and drying it to obtain the modified fly ash.

8. The composite adsorption material according to claim 7, characterized in that The organic solvent is anhydrous ethanol or anhydrous propanol, the heating temperature is 50°C-70°C, the mass ratio of the organic solvent to the candelilla wax is 5-20, more preferably 10-15; preferably, the fly ash is fly ash floating beads, the sintering temperature of the fly ash floating beads is 1000°C-1200°C, the particle size of the fly ash floating beads is 1-300 μm, more preferably 30-100 μm, and the specific surface area is 300-360 cm 2 / g; the volume ratio of the organic solvent to the fly ash is 1-5, more preferably 2-3; the drying temperature is 50℃-70℃, more preferably 50℃-60℃.

9. A method for preparing the composite adsorption material according to any one of claims 1 to 8, comprising the following steps: The microbial flocculant is dissolved in a solvent, and the modified fly ash is added and immersed for 24-72 hours, and then filtered and freeze-dried to obtain a microbial flocculant-modified fly ash composite adsorption material; The solvent is one of ethanol, glycerol, propanol and ethylene glycol; the immersion is carried out under ultrasonic conditions; the freeze-drying temperature is -40 to -60°C, and the freeze-drying time is 24-48 hours.

10. A use of the composite adsorbent material according to any one of claims 1 to 8 for treating fracturing fluid flowback fluid, wherein the amount of the composite adsorbent material is 100-500 g / t, more preferably 200-300 g / t; The concentration of suspended matter in the fracturing fluid backflow is 100-1000 mg / L, more preferably 300-800 mg / L; the concentration of petroleum organic matter is 50-800 mg / L, more preferably 200-750 mg / L; the composite adsorption material is added to the fracturing backflow fluid and stirred for 5-30 minutes, preferably, heated to 20°C-30°C.

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