A cleaning combined with advanced oxidation remediation method for soil contaminated with high concentrations of petroleum hydrocarbons

Abstract

The present invention relates to a cleaning combined with advanced oxidation remediation method for soil contaminated by high-concentration petroleum hydrocarbons. It mainly solves the problem of low treatment efficiency and poor remediation effect of the existing remediation process. The method comprises: step 1, pre-treating the soil to be remediated; step 2, cleaning the soil to be remediated: adding the prepared soil cleaning liquid to the cleaning tank containing the soil to be remediated, heating and stirring the cleaning tank to obtain a mixed liquid, centrifuging the obtained mixed liquid to separate the mixed liquid into three layers, recovering the upper oil phase and the middle layer cleaning liquid, separating and collecting the lower layer of contaminated soil; step 3, oxidizing the soil to be remediated: adding an oxidant and an appropriate amount of cleaning liquid to the collected contaminated soil, so that the humidity of the soil reaches 60% to 75%, and oxidizing for 3 to 5 days. For soil contaminated by high-concentration petroleum hydrocarbons, the method can achieve three-phase separation of soil, cleaning liquid and crude oil, and the chemical agents used in the treatment process have good biodegradability, high treatment efficiency and low energy consumption.

Description

Technical field:

[0001] The invention relates to the field of soil remediation, and in particular to a cleaning combined with advanced oxidation remediation method for soil contaminated by high-concentration petroleum hydrocarbons. Background technology:

[0002] With the rapid development of the petroleum industry, crude oil spillage or leakage is inevitable during the process of oil extraction, storage, transportation and refining, making the problem of oil-contaminated soil increasingly serious. Petroleum hydrocarbon-contaminated soil has great damage and threats to humans and the ecological environment. The physical and chemical properties of soil contaminated by high concentrations of petroleum hydrocarbons will change greatly, the soil porosity will decrease, the microbial community structure will be destroyed, and plants will not be able to grow. Petroleum hydrocarbon-contaminated soil has the characteristics of slow migration and degradation of pollutants, difficulty in pollution control, and long control cycle.

[0003] At present, there are three main types of soil remediation methods: physical remediation, chemical remediation, and biological remediation. These three remediation methods have their own characteristics and limitations. The main physical remediation methods include: incineration, solidification, gas phase extraction, etc. Physical remediation technology has high energy consumption, requires special equipment, has high processing costs, large workload, and is prone to secondary pollution. It can only treat small areas of contaminated soil; chemical remediation methods mainly include: chemical oxidation, chemical cleaning, etc. Chemical cleaning is often used for the remediation of high-concentration petroleum hydrocarbon contaminated soil, but the limitation of chemical cleaning is that it has limited effect on the removal of petroleum hydrocarbons in contaminated soil. Although chemical oxidation can achieve a certain treatment effect in treating petroleum hydrocarbon contaminated soil, the use of a large amount of chemical oxidants can easily destroy the soil aggregate structure. At the same time, there are problems such as high processing costs and secondary pollution. It is only suitable for the remediation of low-concentration petroleum hydrocarbon contaminated soil; biological remediation technology is usually only suitable for the remediation of soil with a small degree of petroleum hydrocarbon contamination. For soil contaminated with high concentrations of petroleum hydrocarbons, it is difficult for microorganisms to survive and cannot perform degradation and remediation of petroleum hydrocarbons. At the same time, biological remediation has the problems of slow process and sensitivity to the soil environment. Site conditions and environmental factors have a great impact on its remediation effect, and the remediation effect is unstable. Summary of the invention:

[0004] The present invention aims to overcome the problems of low treatment efficiency and poor repair effect of the existing repair process in the background technology, and provide a cleaning combined with advanced oxidation repair method for soil contaminated with high concentration of petroleum hydrocarbons. The method can achieve three-phase separation of soil, cleaning liquid and crude oil for soil contaminated with high concentration of petroleum hydrocarbons, and the chemical agents used in the treatment process have good biodegradability, high treatment efficiency and low energy consumption.

[0005] The present invention solves the problem through the following technical solution: A method for cleaning and combining advanced oxidation remediation of soil contaminated with high concentrations of petroleum hydrocarbons, comprising the following steps:

[0006] Step 1: pre-treat the soil to be repaired;

[0007] Step 2, cleaning the soil to be repaired: preparing a soil cleaning solution, adding the prepared soil cleaning solution to a cleaning tank containing the soil to be repaired, heating and stirring the cleaning tank to obtain a mixed solution, centrifuging the obtained mixed solution to separate the mixed solution into three layers, an upper oil phase, a middle water phase, and a bottom contaminated soil; recovering the upper oil phase and the middle cleaning solution, and separating and collecting the lower contaminated soil;

[0008] Step 3: Oxidation treatment of the soil to be repaired: Add an oxidant and an appropriate amount of the cleaning solution prepared in step (2) to the contaminated soil separated and collected in step (2), so that the moisture of the soil reaches 60% to 75%, stir evenly, and oxidize for 3 to 5 days to obtain the repaired soil.

[0009] Preferably, in step (2), the soil cleaning solution is prepared by dissolving a surfactant, a cosolvent and a chelating agent in water to form a soil cleaning solution.

[0010] Preferably, the mass ratio of the added cleaning liquid to the contaminated soil is in the range of 6:1 to 3:1; the mass ratio of the surfactant, the cosolvent and the chelating agent is 0.2 to 0.5: 0.6 to 1.5: 2 to 6.

[0011] Preferably, the surfactant is a combination of octadecyl hydroxypropyl betaine phosphate, hexadecyl propyl hydroxysulfobetaine, and alkyl diphenyl ether disulfonate; the cosolvent is isopropyl alcohol; and the chelating agent is a mixture of sodium polyphosphate and sodium citrate.

[0012] Preferably, the mass ratio of octadecyl hydroxypropyl betaine phosphate, hexadecyl propyl hydroxysulfobetaine, and alkyl diphenyl oxide disulfonate is 1:1:1 to 10:2:1; the mass ratio of sodium polyphosphate to sodium citrate is 1:2 to 3:1.

[0013] Preferably, the oxidant in step (3) comprises sodium persulfate, urea peroxide and potassium ferrate; in step (3), the amount of sodium persulfate added is 1% to 2% of the mass of the contaminated soil, the amount of urea peroxide added is 0.5% to 1% of the mass of the contaminated soil, and the amount of potassium ferrate added is 0.2% to 1.2% of the mass of the contaminated soil.

[0014] Preferably, in the step (3), the oxidation temperature during the oxidation treatment of the contaminated soil is 45° C. to 55° C., the oxidation time is 3 to 5 days, and the soil is turned over 3 to 5 times a day during the oxidation process.

[0015] Preferably, the petroleum hydrocarbon content of the soil contaminated with high concentration of petroleum hydrocarbons is ≥ 15wt%; and the petroleum hydrocarbon content of the soil contaminated with high concentration of petroleum hydrocarbons after restoration is ≤ 0.45wt%.

[0016] Preferably, the soil pretreatment method in step (1) comprises collecting soil contaminated with high concentration of petroleum hydrocarbons, crushing the collected soil contaminated with high concentration of petroleum hydrocarbons, removing impurities, mixing the soil, and placing the soil in a soil cleaning tank.

[0017] Preferably, in step (2), the cleaning tank is heated to 60° C. to 80° C. and stirred for 1 hour; the obtained mixed solution is centrifuged at a speed of 5000 r / min for 8 minutes.

[0018] Compared with the above background technology, the present invention has the following beneficial effects:

[0019] (1) The surfactant used in the contaminated soil cleaning process of the present invention is an effective combination of an amphoteric surfactant and an anionic sub-surfactant, which can promote the exfoliation of petroleum hydrocarbons from the soil surface and disperse into the water phase. At the same time, the addition of a chelating agent can complex with heavy metal ions in the soil system, reduce the influence of metal ions on the activity of the surfactant, and improve the cleaning effect of the contaminated soil.

[0020] (2) The oxidants used in the contaminated soil oxidation process of the present invention are sodium persulfate, urea peroxide and potassium ferrate, wherein potassium ferrate produces Fe3+ after a redox reaction with petroleum hydrocarbons, which can further activate sodium persulfate and urea peroxide to produce a Fenton-like reaction and continue to oxidize the residual petroleum hydrocarbons in the soil. The chelating agent in the cleaning solution can complex with Fe3+ to control the oxidation reaction rate and avoid excessive free radicals from being annihilated and reducing the oxidation effect. The performance of urea peroxide used in the present invention is also better than hydrogen peroxide in the conventional Fenton reaction. The decomposition rate of liquid hydrogen peroxide is too fast, resulting in a low oxidation efficiency, while urea peroxide has a certain slow release of hydrogen peroxide, which can improve the oxidation reaction efficiency. At the same time, the urea released after the reaction can supplement the nitrogen source for the soil, increase soil nutrients, and is conducive to the ecological recovery of the contaminated soil in the later stage.

[0021] (3) The present invention provides a method for cleaning and combining advanced oxidation remediation of soil contaminated with high concentrations of petroleum hydrocarbons, which has the advantages of simple process, high treatment efficiency, low energy consumption, and easy industrial implementation. For soil contaminated with high concentrations of petroleum hydrocarbons, the three-phase separation of soil, cleaning liquid, and crude oil can be achieved, and the chemical agents used in the treatment process have good biodegradability, which has significant environmental and economic benefits. Specific implementation method:

[0022] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical scheme of the present invention is now described in detail. However, it is worth noting that in the detailed description of the present invention below, some specific details are described in detail, but are not limited to these embodiments. For the parts that are not described in detail, those skilled in the art can also fully understand the present invention.

[0023] A method for cleaning and combining advanced oxidation remediation of soil contaminated with high concentrations of petroleum hydrocarbons comprises the following steps:

[0024] Step 1: Pre-treat the soil to be repaired: collect soil contaminated with high concentrations of petroleum hydrocarbons, crush it, remove impurities, mix it, and then place it in a cleaning tank;

[0025] Step 2, cleaning the soil to be repaired: dissolving the surfactant, the cosolvent and the chelating agent in water to prepare a soil cleaning solution, adding the prepared soil cleaning solution to a cleaning tank containing the soil to be repaired, heating the tank body temperature to 60°C to 80°C, stirring for 1 hour to obtain a mixed solution, centrifuging the obtained mixed solution at a speed of 5000r / min for 8 minutes, and the mixed solution after centrifugation is divided into three layers, an upper oil phase, a middle water phase, and a bottom contaminated soil; recovering the upper oil phase and the middle layer cleaning solution, separating and collecting the lower contaminated soil;

[0026] The mass ratio of the added cleaning liquid to the contaminated soil is in the range of 6:1 to 3:1; the mass ratio of the surfactant, the cosolvent and the chelating agent is 0.2 to 0.5: 0.6 to 1.5: 2 to 6.

[0027] The surfactant is a combination of octadecyl hydroxypropyl betaine phosphate, hexadecyl propyl hydroxysulfobetaine and alkyl diphenyl ether disulfonate; the cosolvent is isopropyl alcohol; and the chelating agent is a mixture of sodium polyphosphate and sodium citrate.

[0028] The mass ratio of octadecyl hydroxypropyl betaine phosphate, hexadecyl propyl hydroxysulfobetaine and alkyl diphenyl ether disulfonate is 1:1:1-10:2:1; the mass ratio of sodium polyphosphate and sodium citrate is 1:2-3:1.

[0029] Step 3, oxidizing the soil to be repaired: adding oxidants such as sodium persulfate, urea peroxide, potassium ferrate and an appropriate amount of the cleaning solution prepared in step (2) to the contaminated soil separated and collected in step (2), so that the soil moisture is 60% to 75%, stirring evenly, and oxidizing for 3 to 5 days to obtain the repaired soil.

[0030] The amount of sodium persulfate added is 1% to 2% of the mass of the contaminated soil, the amount of urea peroxide added is 0.5% to 1% of the mass of the contaminated soil, and the amount of potassium ferrate added is 0.2% to 1.2% of the mass of the contaminated soil.

[0031] The oxidation temperature during the contaminated soil oxidation treatment process is 45° C. to 55° C.; the soil is turned over 3 to 5 times a day during the oxidation process.

[0032] The petroleum hydrocarbon content of the soil contaminated with high concentration of petroleum hydrocarbons is ≥15wt%; the petroleum hydrocarbon content of the soil contaminated with high concentration of petroleum hydrocarbons after restoration is ≤0.45wt%.

[0033] Example 1

[0034] The soil contaminated by high concentration of petroleum hydrocarbons comes from Daqing Oilfield. The soil is dark brown and has a pungent smell. The experimental measurement shows that the petroleum hydrocarbon content of the contaminated soil is 22% and the water content is 3%.

[0035] The specific repair steps are:

[0036] (1) Soil pretreatment: 100 g of soil contaminated with high concentrations of petroleum hydrocarbons from Daqing Oilfield was crushed, impurities removed, mixed, and then placed in a cleaning tank;

[0037] (2) Soil water washing treatment: 0.15 g of surfactant octadecyl hydroxypropyl betaine phosphate, 0.1 g of hexadecyl propyl hydroxysulfobetaine, 0.1 g of alkyl diphenyl ether disulfonate, 1 g of cosolvent isopropyl alcohol, 4 g of chelating agent sodium polyphosphate, and 2 g of sodium citrate were dissolved in water to form a soil washing solution. 500 ml of the prepared soil washing solution was added to a washing tank containing the soil to be repaired, the tank body temperature was heated to 80°C, and stirred for 1 hour to obtain a mixed solution. The obtained mixed solution was then centrifuged at a speed of 5000 r / min for 8 minutes. After centrifugation, the mixed solution was separated into three layers, an upper oil phase, a middle water phase, and a bottom soil phase. The upper oil phase and the middle layer washing solution were recovered, and the lower contaminated soil was separated and collected.

[0038] (3) Soil oxidation treatment: add 1.5 g of sodium persulfate, 0.75 g of urea peroxide, 0.8 g of potassium ferrate and the soil cleaning solution prepared in step (2) to the contaminated soil separated and collected in step (2) until the soil moisture reaches 65%, stir evenly, oxidize at 50°C, oxidize for 4 days, and turn the soil 4 times a day. The repaired soil can be obtained.

[0039] Example 2

[0040] The soil contaminated by high concentration of petroleum hydrocarbons comes from Jilin Oilfield. The soil is dark brown and has a pungent smell. The experimental measurement shows that the petroleum hydrocarbon content of the contaminated soil is 18% and the water content is 5%.

[0041] The specific repair steps are:

[0042] (1) Soil pretreatment: 100 g of soil contaminated with high concentrations of petroleum hydrocarbons from Jilin Oilfield was crushed, impurities removed, mixed, and then placed in a cleaning tank;

[0043] (2) Soil water washing treatment: 0.12 g of surfactant octadecyl hydroxypropyl betaine phosphate, 0.08 g of hexadecyl propyl hydroxysulfobetaine, 0.05 g of alkyl diphenyl ether disulfonate, 0.75 g of cosolvent isopropyl alcohol, 1.5 g of chelating agent sodium polyphosphate, and 1.5 g of sodium citrate were dissolved in water to form a soil washing solution. 400 ml of the prepared soil washing solution was added to a washing tank containing the soil to be repaired. The tank body temperature was heated to 65°C and stirred for 1 hour to obtain a mixed solution. The obtained mixed solution was then centrifuged at a speed of 5000 r / min for 8 minutes. After centrifugation, the mixed solution was divided into three layers, an upper oil phase, a middle water phase, and a bottom soil phase. The upper oil phase and the middle layer washing solution were recovered, and the lower contaminated soil was separated and collected.

[0044] (3) Soil oxidation treatment: add 1.4 g of sodium persulfate, 0.6 g of urea peroxide, 0.6 g of potassium ferrate and the soil cleaning solution prepared in step (2) to the contaminated soil separated and collected in step (2) until the soil moisture reaches 60%, stir evenly, oxidize at 45°C, oxidize for 3 days, and turn the soil 3 times a day. The repaired soil can be obtained.

[0045] Example 3

[0046] The soil contaminated by high concentration of petroleum hydrocarbons comes from Daqing Oilfield. The soil is black and has a pungent smell. The experiment shows that the petroleum hydrocarbon content of the contaminated soil is 31% and the water content is 3%.

[0047] The specific repair steps are:

[0048] (1) Soil pretreatment: 100 g of soil contaminated with high concentrations of petroleum hydrocarbons from Daqing Oilfield was crushed, impurities removed, mixed, and then placed in a cleaning tank;

[0049] (2) Soil washing treatment: 0.4 g of surfactant octadecyl hydroxypropyl betaine phosphate, 0.06 g of hexadecyl propyl hydroxysulfobetaine, 0.04 g of alkyl diphenyl ether disulfonate, 1.5 g of cosolvent isopropyl alcohol, 4.5 g of chelating agent sodium polyphosphate, and 1.5 g of sodium citrate were dissolved in water to form a soil washing solution. 550 ml of the prepared soil washing solution was added to a washing tank containing the soil to be repaired, the tank body temperature was heated to 75°C, and stirred for 1 hour to obtain a mixed solution. The obtained mixed solution was then centrifuged at a speed of 5000 r / min for 8 minutes. After centrifugation, the mixed solution was divided into three layers, an upper oil phase, a middle water phase, and a bottom soil phase. The upper oil phase and the middle layer washing solution were recovered, and the lower contaminated soil was separated and collected.

[0050] (3) Soil oxidation treatment: Add 1.8 g of sodium persulfate, 1 g of urea peroxide, 1.1 g of potassium ferrate and the soil cleaning solution prepared in step (2) to the contaminated soil separated and collected in step (2) until the soil moisture reaches 70%, stir evenly, oxidize at 55°C, oxidize for 5 days, and turn the soil 4 times a day. The repaired soil can be obtained.

[0051] Example 4

[0052] The soil contaminated by high concentration of petroleum hydrocarbons comes from Liaohe Oilfield. The soil is dark brown and has a pungent smell. The experimental measurement shows that the petroleum hydrocarbon content of the contaminated soil is 26% and the water content is 5%.

[0053] The specific repair steps are:

[0054] (1) Soil pretreatment: 100 g of soil contaminated with high concentrations of petroleum hydrocarbons from Liaohe Oilfield was crushed, impurities removed, mixed, and then placed in a cleaning tank;

[0055] (2) Soil washing treatment: 0.2 g of surfactant octadecyl hydroxypropyl betaine phosphate, 0.04 g of hexadecyl propyl hydroxysulfobetaine, 0.02 g of alkyl diphenyl ether disulfonate, 1.4 g of cosolvent isopropyl alcohol, 1.2 g of chelating agent sodium polyphosphate, and 2.2 g of sodium citrate were dissolved in water to form a soil washing solution, 450 ml of the prepared soil washing solution was added to a washing tank, the tank body temperature was heated to 70°C, and stirred for 1 hour to obtain a mixed solution, and then the obtained mixed solution was centrifuged at a speed of 5000 r / min for 8 minutes. After centrifugation, the mixed solution was divided into three layers, an upper oil phase, a middle water phase, and a bottom soil phase; the upper oil phase and the middle layer washing solution were recovered, and the lower contaminated soil was separated and collected;

[0056] (3) Soil oxidation treatment: add 1.4g sodium persulfate, 0.8g urea peroxide, 0.9g potassium ferrate and the soil cleaning solution prepared in step (2) to the contaminated soil separated and collected in step (2) until the soil moisture reaches 65%, stir evenly, oxidize at 50°C, oxidize for 3 days, and turn the soil 5 times a day. The repaired soil can be obtained.

[0057] The results of the petroleum hydrocarbon content after the restoration of the high-concentration petroleum hydrocarbon contaminated soil in Examples 1 to 4 are shown in Table 1 below:

[0058] Table 1

[0059]

[0060] The results in the above table show that the method of the present invention based on cleaning combined with advanced oxidation to repair soil contaminated with high concentrations of petroleum hydrocarbons can effectively remove petroleum hydrocarbon substances in the soil.

[0061] The above description does not limit the present invention in any form. Although the present invention has been disclosed as above through the embodiments, the above does not limit the present invention. Any technician familiar with the profession can make some changes or modify the technical contents disclosed above into equivalent embodiments with equivalent changes without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A method for cleaning and combining advanced oxidation remediation of soil contaminated by high concentrations of petroleum hydrocarbons, characterized in that: The following steps are involved: Step 1: pre-treat the soil to be repaired; Step 2, cleaning the soil to be repaired: putting the pretreated soil to be repaired into a cleaning tank; preparing a soil cleaning solution, adding the prepared soil cleaning solution into the cleaning tank containing the soil to be repaired, heating and stirring the cleaning tank to obtain a mixed solution, centrifuging the obtained mixed solution to separate the mixed solution into three layers, an upper oil phase, a middle water phase, and a bottom contaminated soil; recovering the upper oil phase and the middle cleaning solution, and separating and collecting the lower contaminated soil; Step 3, oxidizing the soil to be repaired: adding an oxidant and an appropriate amount of the cleaning solution prepared in step 2 to the contaminated soil separated and collected in step 2, so that the soil moisture reaches 60% to 75%, stirring evenly, and oxidizing for 3 to 5 days to obtain the repaired soil; The step 2 of preparing the soil cleaning solution is as follows: dissolving the surfactant, the cosolvent and the chelating agent in water to form a soil cleaning solution; The surfactant is a combination of octadecyl hydroxypropyl betaine phosphate, hexadecyl propyl hydroxysulfobetaine, and alkyl diphenyl ether disulfonate; the chelating agent is a mixture of sodium polyphosphate and sodium citrate; The mass ratio of octadecyl hydroxypropyl betaine phosphate, hexadecyl propyl hydroxysulfobetaine, and alkyl diphenyl ether disulfonate is 1:1:1 to 10:2:1; the mass ratio of sodium polyphosphate to sodium citrate is 1:2 to 3:1; The oxidant in step 3 includes sodium persulfate, urea peroxide and potassium ferrate; the amount of sodium persulfate added is 1% to 2% of the mass of the contaminated soil, the amount of urea peroxide added is 0.5% to 1% of the mass of the contaminated soil, and the amount of potassium ferrate added is 0.2% to 1.2% of the mass of the contaminated soil.

2. The cleaning combined with advanced oxidation remediation method for soil contaminated with high concentrations of petroleum hydrocarbons according to claim 1 is characterized in that: The mass ratio of cleaning liquid to contaminated soil is 6:1 to 3:

1.

3. The cleaning combined with advanced oxidation remediation method for soil contaminated with high concentrations of petroleum hydrocarbons according to claim 1 is characterized in that: The co-solvent is isopropanol.

4. The cleaning combined with advanced oxidation remediation method for soil contaminated with high concentrations of petroleum hydrocarbons according to claim 1 is characterized in that: In the step 3, the oxidation temperature during the oxidation treatment of the contaminated soil is 45° C. to 55° C., the oxidation time is 3 to 5 days, and the soil is turned over 3 to 5 times a day during the oxidation process.

5. The cleaning combined with advanced oxidation remediation method for soil contaminated with high concentrations of petroleum hydrocarbons according to claim 1 is characterized in that: The petroleum hydrocarbon content in soil contaminated with high concentration of petroleum hydrocarbons is ≥15wt%; the petroleum hydrocarbon content in soil contaminated with high concentration of petroleum hydrocarbons after remediation is ≤0.45wt%.

6. The cleaning combined with advanced oxidation remediation method for soil contaminated with high concentrations of petroleum hydrocarbons according to claim 1 is characterized in that: The soil pretreatment method in step 1 comprises collecting soil contaminated with high concentration of petroleum hydrocarbons, crushing the collected soil contaminated with high concentration of petroleum hydrocarbons, removing impurities, mixing the soil, and placing the soil in a soil cleaning tank.

7. The cleaning combined with advanced oxidation remediation method for soil contaminated with high concentrations of petroleum hydrocarbons according to claim 1 is characterized in that: In step 2, the cleaning tank is heated to 60° C. to 80° C. and stirred for 1 hour; the obtained mixed solution is centrifuged at a speed of 5000 r / min for 8 minutes.

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