A method for the final disposal of petroleum sludge

Abstract

The application discloses a kind of petroleum sludge terminal disposal method, it is related to petroleum sludge processing technical field.The present application comprises the following steps: S1.pretreatment of petroleum sludge deoiling: using 6% to 12% sodium gluconate, trisodium citrate or L-arginine, petroleum sludge is deoiled pretreatment;S2.washing oil sewage electrochemical treatment: with Fe3O4, Fe-C, Al-Fe nanometer material as catalyst, through electrolytic process, the organic matter in the oily sewage produced in S1 processing process is decomposed;S3.deoiled sludge solidification / stabilization treatment.The present application first washes petroleum sludge with chemical agent, after liquid-solid separation, liquid is electrochemically degraded;The separated solid sludge is solidified with magnesium oxychloride cement, and products such as road bricks are formed, solid waste coal gangue and fly ash are used as admixture in this process, water glass solution is used instead of water, and magnesium oxychloride cement with fast solidification and good air hardening is used as solidifying agent, so that the green management of petroleum sludge is realized.

Description

Technical Field

[0001] This invention relates to the field of petroleum sludge treatment technology, specifically to a method for the final disposal of petroleum sludge. Background Technology

[0002] Oily sludge is mainly generated during the production, refining, storage, and transportation of petroleum, and includes mud, crude oil, emulsified solids produced during refining, and some sediments. Oily sludge has a complex composition, often containing insect eggs, bacteria, oil, and chemical additives in addition to water and crude oil. Therefore, oily sludge poses potential hazards to the environment, public health, safety, and ecosystems. Domestic and international researchers generally follow the principles of reduction, harmlessness, and resource recovery in their exploration of petroleum sludge treatment methods and treatment philosophies. Reduction treatment focuses on reducing the amount of oily sludge generated at the source, while harmlessness and resource recovery focus on the efficient treatment and utilization of oily sludge.

[0003] With the current emphasis on sustainable development, the harmless and resource-oriented treatment of oily sludge has become a major research focus, driven by the goals of environmental protection and petroleum resource recovery. There are numerous methods for treating oily sludge, including chemical cleaning, solvent extraction, centrifugation, flotation and electroflotation, pyrolysis, ultrasonic treatment, supercritical fluid extraction, microwave radiation, biological treatment technologies, and combined treatment methods. Traditional methods such as landfilling, composting, and incineration are no longer suitable for the demands of green and sustainable development, necessitating the development of more environmentally friendly and resource-efficient / harmless treatment and disposal technologies. Landfilling occupies large areas of land, and its leachate poses a potential threat to groundwater. Incineration treats sludge relatively thoroughly, but it is energy-intensive, requires significant initial investment, has high operating costs, and can cause secondary pollution. Composting can treat municipal sludge to some extent, but the fate of the composted products is unclear, the volume treated is small, and the cycle is long. Thermal treatment technology decomposes oily sludge at high temperatures, effectively reducing its volume and recovering valuable components. Compared to other treatment technologies, thermal treatment has a shorter treatment cycle, requires less land, and achieves the best volume reduction effect, reaching 80%-90%. However, thermal treatment technologies have high operating costs and may generate secondary pollution. Bioreactors for treating oily sludge offer advantages such as short treatment cycles and small footprints. However, their treatment costs are higher, their treatment efficiency is relatively poor, and they require further secondary treatment such as centrifugation or heating and drying.

[0004] Solidification / stabilization technology is currently one of the important methods for treating solid waste. It uses inorganic solidifying agents such as cement, water glass, fly ash, clay, and magnesium oxychloride cement, or organic solidifying agents such as urea-formaldehyde resin, polyester, ethylene oxide, and acrylamide gel, or composite solidifying agents, to bind sludge into a solid, which is then cured and shaped to achieve a certain strength, thus transforming solid waste into building materials such as paving bricks. During the solidification process, the physicochemical action of the cementing materials restricts the release of harmful components from the sludge, transforming pollutants into substances with low solubility, low migration, and low toxicity, reducing the erosion of the ecological environment by pollutants in the sludge, thereby mitigating its impact and harm to the environment. This method is simple to operate, low in cost, and highly efficient.

[0005] Currently, environmental protection companies commonly use cement, quicklime, fly ash, and ferrous sulfate as solidifying agents for municipal water plant sludge in their sludge solidification and stabilization processes. These agents react with the moisture in the sludge through a series of chemical and physical reactions, giving the product certain mechanical properties, reducing its moisture content, and meeting landfill or construction soil standards. However, achieving the required water content for landfill or landfill cover soil necessitates the addition of large quantities of industrial products such as cement and lime, leading to resource waste and increasing cement production capacity. Furthermore, cement production processes emit significant amounts of dust and carbon dioxide.

[0006] Therefore, we propose a method for the final disposal of petroleum sludge in order to solve the problems mentioned above. Summary of the Invention

[0007] The purpose of this invention is to provide a method for the final disposal of petroleum sludge, so as to solve the problems currently found in the market as described in the background.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for the final disposal of petroleum sludge, comprising the following steps:

[0009] S1. Oil removal pretreatment of petroleum sludge: Use 6%-12% sodium gluconate, trisodium citrate or L-arginine to pretreat the petroleum sludge for oil removal.

[0010] S2. Electrochemical treatment of oily wastewater: Using Fe3O4, Fe-C, and Al-Fe nanomaterials as catalysts, the organic matter in the oily wastewater generated during the S1 treatment process is decomposed through electrolysis.

[0011] S3. Solidification / stabilization treatment of degreased sludge:

[0012] S3-1. Mix magnesium oxychloride cement with the designed amount of water glass solution, and after it is fully dissolved, add fly ash, coal gangue and oil sludge in sequence, and mix them thoroughly to obtain cement slurry;

[0013] S3-2. Vibrate the obtained cement slurry on a vibrating table for 10 minutes to remove air bubbles, then pour it into a mold, cure it at room temperature for 24 hours, demold it, and then cure it at room temperature in a humid environment for 28 days.

[0014] Preferably, in step S3, the water glass solution contains 5% water glass by mass, and the liquid-to-solid ratio is 0.5.

[0015] Preferably, in S3, the magnesium oxychloride cement is composed of magnesium chloride and light magnesium oxide.

[0016] Preferably, in S3, the ratio of fly ash: coal gangue: petroleum sludge: light magnesium oxide: magnesium chloride is 1:3:6:6.79:3.21.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] This invention treats petroleum sludge using a combined chemical washing-electrochemical-solidification / stabilization technology. First, the petroleum sludge is washed with chemical agents. After liquid-solid separation, the liquid undergoes organic degradation via electrochemistry. The separated solid sludge is then solidified with magnesium oxychloride cement to form products such as paving bricks. In this process, solid waste coal gangue and fly ash are used as admixtures, water glass solution is used instead of water, and magnesium oxychloride cement, which has fast solidification and good air hardening properties, is used as the solidifying agent, thereby achieving green treatment of petroleum sludge.

[0019] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0020] Figure 1 The curves showing the relationship between the oil removal rate of petroleum sludge by sodium gluconate, trisodium citrate, or L-arginine aqueous solution and the reagent concentration and the amount of petroleum sludge used are presented.

[0021] Figure 2 Liquid-to-solid ratio (R) w / s ( ) Schematic diagram of MOC-oil sludge solids with a thickness of 0.4-0.9;

[0022] Figure 3 The graph shows the relationship between the liquid-to-solid ratio and the curing time and compressive strength of magnesium oxychloride cement for oily sludge.

[0023] Figure 4 The graph shows the relationship between the amount of petroleum sludge used (left) and the oil content in the sludge (right) and the compressive strength of MOC-oil sludge solids.

[0024] Figure 5Schematic diagram of MOC-oil sludge solids doped with water glass and fly ash respectively;

[0025] Figure 6 This is a schematic diagram of MOC-oil sludge solidified body simultaneously doped with water glass and fly ash, where SU: oil content of petroleum sludge is 11.5% and SV: oil content of petroleum sludge is 3%.

[0026] Figure 7 A schematic diagram of the compressive strength of MOC-oil sludge solids prepared from petroleum sludge with different oil contents;

[0027] Figure 8 Schematic diagram of flexural strength of MOC-oil sludge solids prepared from petroleum sludge with different oil contents;

[0028] Figure 9 This is a graph showing the compressive strength, flexural strength, and water resistance of MOC (Metal Oxide Cement) – a solidified mass of residual sludge. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Please see Figure 1 A method for the final disposal of petroleum sludge includes the following steps:

[0031] S1. Oil removal pretreatment of petroleum sludge: Use 6%-12% sodium gluconate, trisodium citrate or L-arginine to pretreat the petroleum sludge for oil removal.

[0032] S2. Electrochemical treatment of oily wastewater: Using Fe3O4, Fe-C, and Al-Fe nanomaterials as catalysts, the organic matter in the oily wastewater generated during the S1 treatment process is decomposed through electrolysis.

[0033] S3. Solidification / stabilization treatment of degreased sludge:

[0034] S3-1. Mix magnesium oxychloride cement with the designed amount of water glass solution. Magnesium oxychloride cement is composed of magnesium chloride and light magnesium oxide. The water glass solution contains 5% water glass by mass, and the liquid-to-solid ratio is 0.5. After it is fully dissolved, add fly ash, coal gangue, and oil sludge in sequence, and mix them thoroughly to obtain cement slurry. The ratio of fly ash:coal gangue:oil sludge:light magnesium oxide:magnesium chloride is 1:3:6:6.79:3.21.

[0035] S3-2. Vibrate the obtained cement slurry on a vibrating table for 10 minutes to remove air bubbles, then pour it into a mold, cure it at room temperature for 24 hours, demold it, and then cure it at room temperature in a humid environment for 28 days.

[0036] Experiments: Compressive strength, flexural strength, and water resistance tests were conducted on the cured finished product. Leaching toxicity was determined using the horizontal oscillation method in HJ557-2010 standard. The effects of adjusting material composition and proportions during the curing process on the mechanical properties of the cured product were analyzed, including the influence of factors such as liquid-to-solid ratio, the mass ratio of magnesium oxychloride cement to petroleum sludge, and oil content in the oil sludge. Leaching toxicity evaluation was performed on the MOC-oil sludge solidified body, using the organic matter content in the leachate as the evaluation index. 10 grams of dried MOC-oil sludge solidified body sample powder was taken, and 100 grams of deionized water were added to ensure a liquid-to-solid ratio of 10:1. The extraction bottle was sealed at room temperature and continuously oscillated in a water bath for 8 hours, followed by 16 hours of standing. The leachate was then taken out for total organic carbon (TOC) detection. Wastewater treatment plant residue sludge was cured using the optimized parameters of this invention, and 28-day compressive and flexural strength tests were conducted to analyze the applicability of the curing parameters in wastewater treatment plant sludge treatment.

[0037] Experimental results:

[0038] (1) The amount of petroleum sludge used at 25.0℃ was 30.78 g·L. -1 At this time, the oil removal rates of sodium gluconate, L-arginine, and trisodium citrate on petroleum sludge first increased and then tended to reach equilibrium with the increase of the washing agent concentration. The washing agent concentration was 10.0 g·L⁻¹. -1 At that time, the oil removal rate reached its maximum value of 61%, such as Figure 1 As shown in the left figure; the concentration of the cleaning agent is 10.0 g·L. -1 At that time, the oil removal rate first decreased and then tended to reach equilibrium with the increase of sludge dosage. Relatively speaking, sodium gluconate had a better oil removal effect than trisodium citrate and L-arginine. Figure 1 As shown in the right figure.

[0039] (2) Magnesium oxychloride cement (MOC) independently solidifies petroleum sludge. When the molar ratio of magnesium oxide to magnesium chloride is 5.0 and the mass ratio of oily sludge to MOC is 0.89, the oil content in the petroleum sludge is 11.5%, and the solidified product is as follows: Figure 2 As shown; liquid-to-solid ratio (R) w / s As the compressive strength of the oil sludge-MOC solidified body gradually increases from 0.4 to 0.9, the maximum compressive strength after 28 days is 21.3 MPa. Figure 3 As shown.

[0040] (3) When magnesium oxychloride cement is used to independently solidify petroleum sludge, the compressive strength of the MOC-oil sludge solidified body is the highest when the mass ratio of petroleum sludge to MOC is approximately 0.6, and the compressive strength after 28 days can reach 24.2 MPa. Figure 4 Left figure; When the oil content in petroleum sludge decreases, the compressive strength increases to 28.5 MPa, as shown in the figure below. Figure 4 The image on the right.

[0041] (4) Based on (3), water glass was added during the solidification process. When its concentration was 5%, the 28-day compressive strength of the low-oil-content oil sludge solidified body increased to 37.1 MPa; when 5% fly ash was added during the solidification process, the compressive strength of the solidified body was 32.6 MPa. The solidified body image is shown below. Figure 5 .

[0042] (5) Based on the material mass ratio of fly ash: coal gangue: petroleum sludge: light magnesium oxide: magnesium chloride: fly ash = 1:3:6:6.79:3.21, the liquid-solid ratio is 0.5. Simultaneously, 5% water glass is added. The resulting solidified body image is shown below. Figure 6 Reducing the oil content in oily sludge can significantly improve the compressive strength of the product. When the oil content is reduced from 11.5% to 3%, the compressive strength increases from 31.1 MPa to 35.7 MPa, while the flexural strength increases from 10.6 MPa to 11.4 MPa. Figure 7 and Figure 8 At this point, the mass ratio of oil sludge to magnesium oxychloride cement (MOC) is 0.6. While ensuring that the compressive strength of the solidified product is higher than 30 MPa, the comprehensive utilization rate of oil sludge is greatly improved, and the amount of curing agent used is greatly reduced.

[0043] (6) Oily sludge contains organic matter such as crude oil. In order to evaluate the environmental impact of MOC-oily sludge solidification material as a building material, a leaching toxicity test was carried out on the solidification material. The TOC test analysis was performed on the leachate and leachate solids, and the organic matter leaching rate was calculated according to Formula 1. The results of the organic matter leaching test are shown in Table 1.

[0044]

[0045] Where: TOC L and TOC o These represent the organic matter content in the leachate and the initial organic matter content in the consolidated material, respectively, in mg·L⁻¹. -1 .

[0046] As shown in Table 1, at 25℃, the maximum leaching rate of organic matter in the samples was 0.392%, and the minimum leaching rate was 0.329%. This result indicates that approximately 99% of the organic matter was solidified in the MOC-oil-containing sludge solidification material. This experiment reflects that the organic matter content in the leaching solution of the MOC-oil-containing sludge solidified body after continuous immersion in water for 8 hours was low, and the solidification rate of organic matter in the experimental samples could reach over 99%, indicating a good solidification effect on organic matter.

[0047] Table 1 Results of organic matter leaching experiments

[0048]

[0049] (7) Solidification effect of wastewater treatment plant residual sludge: Fly ash: Coal gangue: Residual sludge: Light magnesium oxide: Magnesium chloride = 1:3:6:6.79:3.21, where the water contains 5% water glass by mass, and the liquid-to-solid ratio is 0.5. Under this ratio, the compressive strength and flexural strength are 37.3 MPa and 11.6 MPa, respectively. It exhibits good water resistance in neutral or weakly alkaline water environments, with a water resistance index of over 0.8 after 14 days, and its compressive strength still remains above 30 MPa. Figure 9 .

[0050] (8) The product obtained in (7) was subjected to a freeze-thaw test. After 50 freeze-thaw cycles, the compressive strength was 34.8 MPa, and the strength loss rate and mass loss rate were 6.7% and 2.87%, respectively. The curing parameters and leaching temperature were adjusted, and the product was subjected to a leaching test. The leaching results of the organic matter are shown in Table 2. It can be seen that the leaching rate of organic matter is less than 1%, and the curing rate of organic matter can reach more than 99%, indicating a good curing effect on organic matter.

[0051] Table 2 Results of organic matter leaching experiments on MOC-residual sludge solidified bodies

[0052]

[0053]

[0054] In terms of compressive and flexural strength, the solidified product can be used for paving bricks. Its compressive strength meets the requirements of the "Non-Sintered Waste Tailings Bricks" (JC / T 422-2007) MU25 standard (minimum compressive strength of a single brick ≥ 20 MPa). After 50 freeze-thaw cycles, the compressive strength is 34.8 MPa, with a strength loss rate and mass loss rate of 6.7%. Its strength meets the freeze-thaw resistance requirements of the "Non-Sintered Waste Tailings Bricks" (JC / T 422-2007) MU25 standard (compressive strength after freezing ≥ 22 MPa). The dry mass loss rate of a single brick is 2.87%, slightly higher than 2.0%, indicating room for improvement in mass loss. From the leaching toxicity test results, the leaching rate of organic matter in both oil sludge and residual sludge is low, and 99% of the organic matter can be stabilized in the solidified body, resulting in minimal environmental impact.

[0055] This invention emphasizes the treatment of solid waste. After MOC solidification, organic matter in oily sludge and residual sludge can be stabilized in the solidified body, providing technical parameters for the final disposal and comprehensive utilization of oily sludge and residual sludge. The process is simple, the solidification speed is fast, and stable strength can be achieved in 7 days of curing. The curing method is simple, requiring only room temperature curing and has low humidity requirements. This invention provides a conceptual and theoretical basis for the comprehensive utilization of oily sludge and can be extended to the treatment of residual sludge in wastewater treatment plants.

[0056] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for the final disposal of petroleum sludge, characterized in that, Includes the following steps: S1. Oil removal pretreatment of petroleum sludge: Use sodium gluconate, trisodium citrate or L-arginine at a mass concentration of 6%-12% to pretreat the petroleum sludge for oil removal. S2. Electrochemical treatment of oily wastewater: Using Fe3O4, Fe-C, and Al-Fe nanomaterials as catalysts, the organic matter in the oily wastewater generated during the S1 treatment process is decomposed through electrolysis. S3. Solidification / stabilization treatment of degreased sludge: S3-1. Mix magnesium oxychloride cement with the designed amount of water glass solution, and after it is fully dissolved, add fly ash, coal gangue and oil sludge in sequence, and mix them thoroughly to obtain cement slurry; magnesium oxychloride cement is composed of magnesium chloride and light magnesium oxide; the water glass solution contains 5% water glass by mass and the liquid-to-solid ratio is 0.5; S3-2. Vibrate the obtained cement slurry on a vibrating table for 10 minutes to remove air bubbles, then pour it into a mold, cure it at room temperature for 24 hours, demold it, and then cure it at room temperature in a humid environment for 28 days.

2. The method for terminal disposal of petroleum sludge according to claim 1, characterized in that: In S3, the material mass ratio is fly ash: coal gangue: petroleum sludge: light magnesium oxide: magnesium chloride = 1:3:6:6.79:3.21.

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