RU2288044C1 - Method of cleaning of the ground from the oil pollutions - Google Patents

Abstract

FIELD: environmental protection; all branches of industry; methods of cleaning of the ground from oil pollutions.

SUBSTANCE: the invention is pertaining to the field of the environmental protection and may be used for cleaning the soils or the ground from the oil products pollutions in all branches of industry dealt with processing, transportation or the oil and oil products storage, and also at elimination of effects of accidents or catastrophes. The ground is introduced with the additive stimulating the growth of the present in the ground oil oxidizing micro-organisms. In the capacity of the additive use the synthetic washing substance (SWS) containing 10-20 % of the surface-active substance (SAS), 30-40 % of phosphates. At that the concentration of SAS compounds 0.1-1 g/kg of the ground. The additive may additionally contain a complex mineral fertilizer with concentration of 0.7 g/kg of the ground, and-or the molasses solution up to the final concentration of sugars of 3-5 g/kg of the ground, and-or the crude oil in the concentration of 0.5 g/kg of the ground. The technical result of the invention is - acceleration of the process of the ground cleaning from the aged pollution, which is present in the surrounding medium of no less than 12 months, with the concentration of the oil products of 30-400 g/kg of the ground at maintaining the efficiency of the cleaning, simplification of the method and reduction of expenditure on the bioremediation.

EFFECT: the invention ensures acceleration of the process of the ground cleaning from the pollutions present in the ground of no less than 12 months and having concentration of 30-400 g/kg of the ground; maintaining the efficiency of the cleaning, simplification of the method and reduction of expenditure on the bioremediation.

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Description

The invention relates to the protection of the environment and can be used to clean the soil or soil from oil pollution in all industries related to the processing, transportation or storage of oil and oil products, as well as in the aftermath of accidents or disasters. This method is effective for cleaning from oil pollution with a long time, i.e. in the environment for at least 12 months, with a concentration of oil products of 30-400 g / kg of soil and in the presence of a pool of hydrocarbon-oxidizing microorganisms in it.

Currently, technologies for the remediation of oil-contaminated soils using in situ biostimulation are more preferable for a number of reasons, including, first of all, economic ones. In some cases, for example, at large scales of pollution, they are the only possible ones. An important stage in this is the selection of techniques for intensifying the functional activity of natural microbial cenoses and especially the group of hydrocarbon-oxidizing microorganisms (UOM).

A known method that can be used to clean the surface of hydrocarbon contaminants, such as petroleum products, greases, fats and oils, for example, for washing technological tanks and soil. The surface of hydrocarbon contaminants is cleaned in a closed cycle with an aqueous solution of detergent capable of emulsifying hydrocarbon contaminants. This method includes washing the surface, regenerating the washing solution by phase separation of the emulsion, followed by separation of the organic phase and returning the aqueous phase to the cleaning cycle. As a washing solution, a solution is used that forms an unstable emulsion with hydrocarbon contaminants containing polyelectrolyte and detergent additives. The phase separation of the emulsion provides a volumetric ratio of organic contaminants and a washing solution of at least 1: 2 (Patent for the invention of the Russian Federation No. 2135304, IPC: 08 V 3/08).

However, the method involves excavating for washing, which is unacceptable for processing a large volume of soil. The method does not take into account the residual content of surface-active substances (surfactants) in the soil and its impact on the environment.

It is known to use the strain Pseudomonas aeruginosa UG-2 producing bio-surfactants (biologically produced surfactants) for cleaning loamy soil from a mixture of alkanes and methylnaphthalene. A significant decrease in tetradecane, hexadecane, and pristin was observed at a surfactant content of 100 mg / kg of soil, with no 2-methylnaphthalene loss observed (Jain DK, Lee H, Trevors JT Effect of addition of Pseudomonas aeruginisa UG-2 inocula or biosurfactants on biodegradation of selected hydrocarbon in soil // Journal of Industrial Micribiology. - 1992. - 28. P.87-93).

However, the use of a bacterial preparation significantly increases the cost of the cleaning process. Not all of the listed substances underwent destruction with this processing method. In addition, the introduction of foreign microorganisms into the environment can upset the balance of the natural microbial community.

A known method of purifying water and soil from petroleum products using sorbents obtained by foaming a composition containing urea-formaldehyde resin, surfactants, an acid curing catalyst, tannic extract of coniferous bark, hydrocarbon-oxidizing microorganisms and, possibly, mineral salts, which are cured and formed. The technical effect consists in obtaining biosorbents in the form of mats, bonn or granules with a reduced content of formaldehyde, and the spent sorbent can be bio-utilized (Patent for the invention of the Russian Federation No. 2191068, IPC: B 01 J 20/30, B 01 J 20/24) .

However, the manufacturing technology of this sorbent is quite complicated. In addition, the proposed method is only the first stage of processing, after which the disposal of the sorbent itself is provided.

There is a method of cleaning the environment from oil and oil hydrocarbons, based on the intensification of destruction processes by introducing natural strains of Arthrobacter globioformis VKPM-1551 and Rhodococcus erythropolis VKPM-8-1550, as well as various adsorbents (sawdust, straw, compost, peat) and surfactants. The drugs can be used both in the form of a microbial component - suspension, thickened paste, dry powder, and in the form of a biological product, which along with the microbial component based on microorganism strains include various adsorbents and surfactants in a concentration of 0.1%. The method is characterized by a wide range of applications for cleaning oil products from water surfaces, soil and other environmental objects (Patent for the invention of the Russian Federation No. 21115727, IPC: C 12 N 1/26, C 02 F 3/34).

However, the method is based on the introduction of foreign microorganisms - destructors into the contaminated object. The disadvantage of this method is also low competitiveness with respect to indigenous microorganisms due to the low growth rates of this group of bacteria. In addition, this technology is expensive due to the additional costs of building, storage and pre-treatment before entering the soil.

Closest to the claimed is a method of restoring soils contaminated with hydrocarbons and other biodegradable substances, based on the stimulation of the activity of endogenous microbial flora that can destroy hydrocarbons by adding nutrients to the treated soil. These additives are substances in oleophilic and hydrophilic form and a structuring agent for aeration. The oleophilic form contains nitrogen and phosphorus (N / P), the hydrophilic form may contain both nitrogen and phosphorus, and nitrogen, phosphorus and potassium (N / P or N / P / K). The oleophilic substance can be presented in the form of a microemulsion, such as a solution of N / P salts in a fat-soluble hydrocarbon solvent, into which surfactants can be added. The hydrophilic substance N / P / K can be used in the form of granules, protected by an anti-diffusion layer. As a structuring agent promoting aerobic biodegradation, straw, wood shavings, sawdust or cores of corn cobs are used, this process is improved in the presence of surfactants. When cleaning, the oleophilic nutrient is sprayed over the surface of the treated soil, then after 2-7 days the structuring agent and the hydrophilic nutrient are distributed, the treated soil is mixed to obtain a fine mixture of all components. The cultivated soil can remain in place or removed and left in the rolls until the hydrocarbon concentration decreases to the desired level. Fertilizer is applied in a form that is slowly washed out by precipitation. To improve the effect, surfactants can be added together with the microemulsion of nutrients in a hydrophobic form. The biological process takes 6-18 months, depending on the intensity of the pollution and the nature of the polluting hydrocarbons, which control the sampling and measurement of their quantity (Patent for the invention of the Russian Federation No. 2135306, IPC: B 09 C 1/08, C 09 K 17/00 )

However, this method is characterized by the duration of the cleaning process. In addition, the introduction of stimulating additives is carried out in several stages, which complicates the processing process.

The objective of the invention is to accelerate the process of cleaning the soil from old pollution in the environment for at least 12 months, with a concentration of oil products of 30-400 g / kg of soil while maintaining cleaning efficiency by stimulating the population of UOM, simplifying the method and reducing the cost of bioremediation.

The problem is solved in that in the method of cleaning the soil from oil pollution, including the introduction of additives into the soil, stimulating the growth of oil-oxidizing microorganisms contained in it, containing surfactants and phosphates, characterized in that synthetic detergent (CMC) containing 10 is used as an additive -20% surfactant 30-40% phosphates, while the concentration of CMC is 0.1-1 g / kg of soil.

The additive additionally contains complex mineral fertilizer in a concentration of 0.7 g / kg of soil.

The additive additionally contains molasses to a final sugar concentration of 3-5 g / kg of soil.

The additive additionally contains crude oil at a concentration of 0.5 g / kg of soil.

After the addition of the additive, the temperature and water conditions of the soil are maintained to ensure the vital function of microorganisms to a residual content of oil pollution.

The synthetic detergent (CMC) introduced into the treated soil stimulates the UOM population by increasing the bioavailability of the oil product and adding an additional source of phosphorus, as it is known that soil contamination with oil leads to a decrease in the content of mobile phosphorus.

The invention is illustrated by drawings, in which Fig. 1 shows the dynamics of the abundance of UOM in soil with old fuel oil pollution for the selected options, Fig. 2 shows the results of stimulation of degradation of petroleum products, and Fig. 3 graphically shows the rate of oil destruction in the experimental and control versions.

The invention is directed to the selection of optimal additives that stimulate an increase in the number and activity of hydrocarbon-oxidizing microorganisms in soils with old oil pollution at a concentration of 30-400 g / kg of soil.

The method is based on the introduction of additives based on CMC into the soil, stimulating the development of oil-oxidizing microorganisms present in contaminated soil (soil) by increasing the bioavailability of the oil product and the addition of a source of phosphorus. The introduction of additives in conjunction with the use of certain modes - temperature, humidity, processing time, accelerates the process of cleaning the soil with old oil contamination while maintaining efficiency and reducing costs. The method can be used both for processing contaminated soils and soils in situ (in situ), and in specially equipped sites on which the extracted soil is placed (ex situ).

To implement the method, the soil is moistened to a total moisture content of 15-17%, for example, tap water through a stationary water supply system or from a nearby freshwater source using a submersible pump or a vacuum barrel, with a small area of the treated area, watering can be done manually from a watering can, when watering, natural precipitation. Used CMC should contain 10-20% surfactant, 30-40% phosphate and should not contain disinfectants. CMC is pre-dissolved in water, application is made by pump through a hose or manually from a watering can, taking into account the fact that the final concentration of surfactants in the soil should be 10-100 mg / kg, depending on the concentration of oil products. When using CMC with a surfactant content of 20% after its preliminary dissolution in water in a ratio of 1:25, this corresponds to 0.33-3.3 l / m ² when oil penetrates to a depth of 10 cm or 3.3-33 l / m ^{3 of} soil . Depending on the concentration of surfactants in the CMC, the amount of soil to be treated and the method of irrigation, the ratio of CMC and water for its dissolution may vary. Mineral fertilizer is applied dry, when using an azofoska (TU 2186-028-07623164-2002), the application rate is 1 kg / m ³ or 100 g / m ² with a contaminant penetration depth of 10 cm. Molasses are introduced using a submersible pump or manually , if necessary, it is diluted with water. The amount of molasses to be added depends on the sugar content in it, to a final sugar content in the soil of 3-5 g / kg. When diluting twice molasses with a sugar content of about 50%, this will be 18-30 l / m ^{3 of} soil or 2-3 l / m of soil surface, respectively, when oil penetrates to a depth of 10 cm. After making the additives, mixing is carried out by disking, harrowing, plowing or using an excavator, depending on the depth of penetration of the pollutant and the condition of the soil. Humidity at the level of 12-17% is maintained by irrigation; regular loosening (1 time in 10 days) is carried out to maintain optimal aeration. The process is recommended to be carried out at a temperature of 19-32 ° C for 2-6 months.

Soil with an old (about 10 years) fuel oil pollution with an initial concentration of oil products of about 380 g / kg was placed in plastic containers in an amount of 1.5 kg. The cleaning process was carried out at room temperature 19-24 ° C with the introduction of various stimulants, periodic loosening and moistening. Microbiological analysis of the initial soil showed that the content of hydrocarbon-oxidizing microorganisms (UOM) in it was 4.0 × 10 ⁴ colony forming units (CFU) / g, which indicated the possibility of stimulation of native microflora.

To stimulate the development of UOM, we used the most accessible and cost-effective additives for industrial use: CMC as an emulsifier and source of phosphorus, mineral fertilizer as azofoska, which is a source of nitrogen, phosphorus and potassium, molasses as an additional readily available source of carbon and biologically active substances. The components were added individually and in various combinations (see table). In one of the options (9), along with a complete set of the above ingredients, additional crude oil was added to partially dissolve the hydrophobic compounds at a concentration of 0.5 g / kg. The CMC used contained 20% of a mixture of surfactants and 40% sodium tripolyphosphate.

Remediation options for contaminated soil Options Additives, g / kg of soil one control - no additives 2 azofoska - 0.7 3 molasses - 6 four CMC - 0.2 5 azofoska - 0.7; molasses - 6 6 azofoska - 0.7; CMC - 0.2 7 molasses - 6; CMC - 0.2 8 azofoska - 0.7; molasses - 6; CMC - 0.2 9 azofoska - 0.7; molasses - 6; CMC 0.2; oil - 0.5

The maximum increase in the number of UOM (about 2 orders of magnitude) was observed after 60 days of cultivation (see figure 1), using only agrotechnical treatment (1), the results were significantly lower. Further, until the end of the experiment, there was no noticeable decrease in the number of UOM. In options 4 and 9, the content of UOM increased most significantly after 2 months of cultivation: approximately 90 times. In figure 1. reflected the dynamics of the number of UOM in the soil with old fuel oil pollution in the options: 1 - agricultural technology; 4 - agricultural technology and CMC; 9 - agricultural technology, fertilizer, molasses, CMC and crude oil. Thus, the development of UOM populations was significantly different and depended, first of all, on the level and age of pollution. The maximum loss of oil products was observed with the introduction of CMC as the only component (4), as well as with the addition of crude oil in addition to the whole complex of stimulants (9) - 58.2 and 56.7% for 3 months, respectively (Fig. 2), and in control without additives (1) - 36.4%.

The presence of surfactants and crude oil contributed to the emulsification and dissolution of heavy oil products, making them more accessible to microorganisms. With the optimal selection of additives, the level of fraction destruction was: hydrocarbons of the paraffin-naphthenic fraction - 61-63%, mono- and bicyclic aromatic hydrocarbons - 50-56%, PAHs - 44-46%, resins and asphaltenes - 42-48%. In figure 2. The destruction of oil products in soil with old fuel oil pollution (380 g / kg) was demonstrated in the following variants: 1 - agricultural technology; 4 - agricultural technology and CMC; 9 - agricultural technology, fertilizer, molasses, CMC and crude oil. The maximum rate of destruction was observed during the first two months of the experiment (figure 3). In option 4, in the first month it reached 0.96% per day, which was equal to 3.7 g / kg, while in the control these indicators were 0.26 and 1.0, respectively. Figure 3 graphically demonstrates the rate of oil destruction in the experimental version of 4 m and control version 1. Over the next month, a noticeable decrease in the rate of destruction of oil products in the experimental version was not observed, and in the control there was a slight increase. However, after three months, the maximum rate (option 4) was only 0.11%, and after six months the rate decreased to 0.06% per day. It can be assumed that the high rate of decomposition of fuel oil is caused by the limitation of pollution, as a result of which the microbial complex adapted to this source of carbon and energy, and the oil products themselves, as a result of partial oxidation, became more accessible for biodegradation.

Based on the studies, it was found that, to stimulate the group of oil-oxidizing microorganisms, it was crucial to add additives that promote emulsification and increase the availability of the pollutant - surfactants and crude oil, as well as additional introduction of mineral nutrition elements. Despite the very high concentration of oil products in soil with old pollution, the level of destruction was high. The maximum rate of degradation was observed during the first two months. After six months with a 60-70% destruction of the hydrocarbon fraction, the rate of decrease of the pollutant in all cases became approximately the same and a slow elimination of residual hydrocarbons occurred. Based on what we can conclude that upon reaching this level, active processing can be stopped. Analysis of the residual surfactant content in the treated soil showed its complete elimination, which indicates the environmental safety of the proposed method. Our studies showed that with an optimal combination of techniques, the degree of destruction exceeded the values in the control by 15-30%. The data obtained indicate the prospects of using this method.

Example 1

The soil was cleaned with old fuel oil pollution at a concentration of about 380 g / kg at the landfill for reclamation at a temperature of 19-27 ° C, periodically loosening and maintaining humidity at the level of 12-17%. Ridges 1 and 2 meters wide were formed from the soil. When cleaning, CMC was used as a stimulating additive at a concentration of 1.0 g / kg of soil with a surfactant content of 20% and tripolyphosphate 40%. CMC was dissolved in water (1:25) and introduced using a submersible pump at the rate of 37 l per m ^{3 of} soil, this amount of solution provided the desired moisture level, so no additional watering was performed. After the addition of the additive, the soil was mixed with an excavator. After 3 months, the decline in oil products amounted to 67%, while in the control without stimulating additives - 44%. Watered at the rate of 20 l / m ³ from a stationary water supply.

Example 2

The soil was cleaned with 10-year-old fuel oil pollution at a concentration of about 260 g / kg at a landfill for reclamation at a temperature of 19-27 ° C, periodic loosening and maintaining humidity at the level of 12-17%. Ridges 1 and 2 meters wide were formed from the soil. When cleaning, the following complex of stimulating additives was used: CMC with a surfactant content of 20% and tripolyphosphate 40%, molasses, azofosk (TU 2186-028-07623164-2002) and oil. CMC was dissolved in water (1:25) and introduced using a submersible pump at the rate of 15 l per m ^{3 of} soil, to a final concentration of 0.4 g / kg of soil. Molasses with an initial sugar content of 45% was diluted in half and introduced using a submersible pump at the rate of 33 l / m ^{3 of} soil, which amounted to 5 g / kg of soil. Azofoska was applied in dry form manually at the rate of 1 kg / m ^{3 of} soil, which was about 0.7 g / kg of soil. Oil was introduced manually at the rate of 0.9 l / m ³ , which amounted to 0.5 g / kg of soil. After adding additives, the soil was watered at the rate of 20 l / m ³ from a stationary water supply and mixed with an excavator. After 2 months, the loss of oil products amounted to 64%, while in the control without stimulating additives - 43%.

Example 3

Soil was cleaned in situ with 2-year-old fuel oil pollution at a concentration of 55 g / kg and a penetration depth of 10-15 cm using CMC - 0.1 and azofoski (TU 2186-028- as stimulating additives (g / kg of soil) 07623164-2002) 9-0.7. CMC was dissolved in water (1:50) and applied manually at the rate of 1 liter per m ^{2 of} soil. Azofoska was applied in dry form manually at the rate of 140 g / m ² , which was about 0.7 g / kg of soil. After 3 months, the decline in oil products amounted to 53.5%. The process took place at a temperature of 20-32 ° C, periodic loosening and watering.

The inventive method makes it possible to process large volumes of contaminated soil, while the technology is carried out without the use of foreign microorganisms that can upset the balance of the natural microbial community.

Claims (5)

1. The method of cleaning the soil from oil pollution, including the introduction into the soil of an additive that stimulates the growth of oil-oxidizing microorganisms contained in it, containing surfactants and phosphates, characterized in that the additive uses a synthetic detergent (CMC) containing 10-20% surfactant, 30-40% of phosphates, while the concentration of CMC is 0.1-1 g / kg of soil. 2. The method according to claim 1, characterized in that the additive further comprises a complex mineral fertilizer in a concentration of 0.7 g / kg of soil. 3. The method according to claim 1, characterized in that the additive further comprises molasses to a final sugar concentration of 3-5 g / kg of soil. 4. The method according to claim 1, characterized in that the additive further comprises crude oil in a concentration of 0.5 g / kg of soil. 5. The method according to claim 1, characterized in that after the addition of the additive, the temperature and water conditions of the soil are maintained to ensure the vital function of microorganisms to a residual content of oil pollution.

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