RU2175580C2 - Composition for cleaning soil to remove oil pollutions and method - Google Patents

Abstract

FIELD: oil pollution removal. SUBSTANCE: composition contains 1-2% of oil-oxidizing microorganisms, 25-35% of fertilizer (manure), and 63-74% of adsorbent. As microorganisms, activated sludge is used obtained from drainage-type waste disposal plants belonging to petroleum refinery. Sludge is picked from distributing chamber of secondary settlers 0-8 h after withdrawal from system for regeneration. Soil cleaning method includes treatment of the latter by indicated composition in combination with a monthly loosening of polluted soil to a depth of 50-55 cm. Optimal contents of adsorbent and activated sludge in composition are found from formulas describing dependence of the degree of biodegradation of petroleum products on content of adsorbent in polluted soil and on activated sludge dose. EFFECT: improved environmental property of composition and improved economical efficiency of soil cleaning process. 2 cl, 5 dwg, 3 tbl

Description

 The invention relates to compositions for cleaning and methods for cleaning the soil from oil pollution and can be used to clean the soil from oil spills and oil pollution.

 A known method of cleaning the soil from oil pollution, in which by introducing into the contaminated environment an aqueous suspension of the bacterial culture of Rhodococcus erythropolis E-15 in a mixture with mineral fertilizer - nitroammophos or nitroammophos and sodium nitrate provides biodegradation of oil pollution (see auth. Certificate. RF N 2019527 , CL C 02 F 3/34, E 02 B 15/04, C 09 K 17/00, 1994).

For reasons that impede the achievement of the following technical result when using the known method, the following disadvantages are present in the known method:
- narrow scope. This bacterial culture uses hydrocarbons with a chain length of C ₁₄ - C ₁₈ as the sole source of carbon and energy;
- cleans only the surface layer of the soil, due to the fact that the microorganisms entering it develop only under aerobic conditions;
- ineffective at high temperatures;
- the application is associated with a significant cost of funds for growing crops;
- the complexity of the preparation and use of the composition;
- there is no evidence of the choice of optimal ratios of the components in the composition.

 A known method of purifying soil and water from oil pollution, in which by introducing into the contaminated environment an aqueous suspension of the bacterial preparation Putidul in a mixture with mineral fertilizer - nitroammophos biodegradation of oil pollution occurs. The drug "Putidul" is made on the basis of the bacterial culture of the natural strain Pseudomonas putida - 36 (see ed. Certificate of the USSR N 1428809, class C 02 F 13/34, E 02 B 15/04, 1988).

For reasons that impede the achievement of the following technical result when using the known method, the following disadvantages are present in the known method:
- the drug "Putidul" is a dry bacterial mass and for its preliminary "revitalization" a laborious set of measures is required that are carried out in the field: heating a large amount of water (5 m ³ ) to a temperature of 28 ^o C, providing aeration for 12-16 hours mixing;
- cleans only the surface soil layer due to the fact that the microorganisms included in it develop only under aerobic conditions;
- has a depressing effect on the natural microbial biocenosis;
- the application is associated with a significant cost of funds for growing crops;
- there is no evidence of the choice of optimal ratios of the components in the composition.

 A known method of cleaning the soil and water from oil pollution, in which by introducing into the contaminated medium an aqueous suspension of the bacterial preparation "Devoroil", which is a consortium of microorganisms Rhodococcus sp. , Rhodococcus maris. , Rhodococcus erythropolis, Pseudomonas stutzeri, Candida sp. , biodegradation of oil pollution is carried out (see ed. certificate of the Russian Federation N 2023686, class C 02 F 3/34, E 02 B 15/04, C 12 P 39/00, 1994).

For reasons that impede the achievement of the following technical result when using the known method, the following disadvantages are present in the known method:
- cleans only the surface soil layer due to the fact that the microorganisms included in it develop only under aerobic conditions;
- the application is associated with a significant cost of funds for growing crops;
- there is no evidence of the choice of optimal ratios of the components in the composition.

 The closest method of the same purpose to the claimed invention according to the totality of features is “Composition for cleaning the soil from oil pollution and a method of cleaning the soil from oil pollution”, in which by treating the soil with the following composition: oil-oxidizing microorganisms, complex fertilizer, adsorbent (wood waste) produce biodegradation of petroleum products (see ed. certificate of the Russian Federation N 2112610, class B 09 C 1/10, C 02 F 3/34, C 12 N 1/26, 1998), adopted as a prototype.

For reasons that impede the achievement of the following technical result when using the known method, the following disadvantages are present in the known method:
- the bacterial preparations Devoroil and Destroil are used as oil-oxidizing microorganisms, the production of which requires material costs, as well as the Putidoyl preparation, the use of which, in addition to the high material costs of its production, is supplemented by a laborious set of works before putting it into the soil . In addition, the drug "Putidul" has a depressing effect on the natural microbial biocenosis;
- there is no evidence of the choice of optimal ratios of the components in the composition.

 The problem to which the invention is directed is to create an optimal, environmentally friendly composition for cleaning the soil from oil pollution, as well as to create a method for cleaning the soil from oil pollution, having a relatively low cost, preserving moisture in the soil for a long time to ensure optimal cleaning conditions.

 The technical result is to increase the efficiency of the method of cleaning the soil from oil pollution, the creation of an optimal, environmentally friendly composition for cleaning soils from oil pollution.

The specified technical result in the implementation of the invention is achieved by the fact that in the known composition for cleaning the soil from oil pollution containing oil-oxidizing microorganisms, fertilizer and adsorbent, as the oil-oxidizing microorganisms, the activated sludge of the sewage treatment plants of the oil refinery is used, taken from the distribution chamber of the secondary clarifiers through 0 - 8 hours after withdrawal from the system for regeneration, and manure, for example, large, is used as complex fertilizer cattle in the following ratio of components in the mixture, wt.%:
Active sludge - 1 - 2
Manure - 25-35
Adsorbent - 63-74
In addition, in the known method of cleaning the soil from oil pollution, including treating the contaminated medium with a composition for cleaning the soil, in addition to this, a complex fertilizer is additionally periodically added to the contaminated medium, manure is used as a complex fertilizer, and additionally once a month the soil is loosened to a depth 50-55 cm, and when the soil moisture is less than 50%, it is irrigated, the optimal ratio of the components of the contaminated soil / adsorbent mixture is selected according to the step and biodegradation of petroleum products from the adsorbent content in a mixture obtained, for example, as a result of processing experimental data (see table 1 and Fig. 1) using the least square method (see Kudrin A.N., Ponomareva G.T. experimental and clinical medicine. - M .: Medizdat, 1967, - p. 138):
S (n) = k (1-e ^{-n / T} ), (1)
where S is the degree of biodegradation of oil products,%;
n is the ratio of the amount of soil (volume units) to the amount of adsorbent (volume units);
k is the scale factor used to calculate the degree of biodegradation of petroleum products with the adsorbent introduced, depending on the coordinate scale;
T is the time constant of biodegradation of oil products with an adsorbent introduced;
e ≈ 2.718,
in this case, the optimal ratio of the components is chosen at the intersection of the graph of the function S (n) with a horizontal line less by 3-5% of the established value of the function, then, according to the graph of the dependence of the degree of biodegradation of oil products on their initial concentration, obtained, for example, experimentally, choose the optimal field of application of the proposed composition, as the area of maximum biodegradation of oil products, the optimal dose of activated sludge is determined by the formula for the degree of biodegradation of oil products from a dose of activated sludge, obtained, for example, as a result of processing experimental data (see Table 3 and Fig. 5) using the least square method (see Kudrin AN, Ponomareva GT. The use of mathematics in experimental and clinical medicine. - M .: Medizdat, 1967, - p. 138):
S (d) = k ₁ (1-e ^{-d / Q} ), (2)
where S is the degree of biodegradation of oil products,%;
d is the dose of activated sludge, mg / kg of soil;
k ₁ - scale factor used to calculate the degree of biodegradation of oil products with activated sludge, depending on the scale of coordinates;
Q is the time constant of biodegradation of petroleum products with activated sludge;
e ≈ 2.718,
the optimal dose of activated sludge is chosen at the point of intersection of the graph of function S (d) with a horizontal line less than 3-5% of the established value of the function, the dose of manure introduced into the soil is selected taking into account the livelihoods of activated sludge and further use of soil in rural an economy from the range of 2-2.5 kg / m ² (17-21.3 t / ha).

 Improving the efficiency of the method of cleaning the soil from oil pollution is achieved by the fact that the economic cost of producing components of the composition is lower than in the known method (in the prototype, the cost of the preparation for cleaning 1 ha of soil from oil pollution is 7200 r / ha, and in the proposed method, activated sludge is production waste). Thus, the use of this composition for biodegradation of petroleum products gives a synergistic effect: the cost of production of oil-oxidizing microorganisms is reduced and there is no cost of disposal of activated sludge and manure. To determine the optimal composition, the values of the components are taken from the graphs (see Figs. 1-5) obtained as a result of processing the data of experimental studies on biodegradation of oil products in systems with different content of components (see Table 1-3).

 The preparation of the composition for cleaning the soil from oil pollution is as follows.

 Example 1

 1.0 kg of activated sludge, 30.0 kg of cattle manure and 69.0 kg of adsorbent (sawdust) are mixed in an open area or in a mixer. Stirring is carried out for 0.5-1.0 hours to obtain a homogeneous mixture. The resulting mixture of the composition, wt.%: 1.0 activated sludge, 30.0 cattle manure and 69.0 adsorbent contribute to contaminated soil.

 Example 2

 1.5 kg of activated sludge, 32.0 kg of cattle manure and 66.5 kg of adsorbent (sawdust) are mixed in an open area or in a mixer. Stirring is carried out for 0.5-1.0 hours to obtain a homogeneous mixture. The resulting mixture composition, wt.%: 1.5 activated sludge, 32.0 cattle manure and 66.5 adsorbent contribute to the contaminated soil.

 The method is as follows.

 Processing of contaminated soil is carried out in the spring-summer period. In the soil impregnated with contaminants, the proposed composition is introduced by plowing in the amount of: 1 part of the composition for 4 parts of oil pollution. The optimal soil moisture to ensure favorable living conditions of microorganisms is 50-60% (see Medvedev G.P. Sewerage of cities in Germany. - L .: Stroyizdat, 1981, - 168 p.), Therefore, if the soil moisture is less than 50%, then produce watering. In order to create aeration, soil is loosened once a month, for example, with chisel to a depth of 50-55 cm. In addition, periodic loosening of the soil prevents the evaporation of moisture. The processing efficiency is judged by the reduction of oil saturation (oil destruction) in the treated area. For full soil remediation in the fall, sowing seeds of one- and two-year crops.

 The choice of optimal doses of the components of the composition is carried out using table. 1-3 and FIG. 1-5.

 1. Determination of optimal volumetric ratios in the system "contaminated soil / adsorbent".

In the table. 1 shows the results of biodegradation of petroleum products in systems with a volumetric ratio of contaminated soil / adsorbent from 1: 0.01 to 1: 1. FIG. 1 shows the dependence of the degree of biodegradation of petroleum products on the adsorbent content in the system, which is described by the formula:
S (n) = k (1-e ^{-n / T} ), (1)
where S is the degree of biodegradation of oil products,%;
n is the ratio of the amount of soil (volume units) to the amount of adsorbent (volume units);
k is the scale factor used to calculate the degree of biodegradation of petroleum products with the adsorbent introduced, depending on the coordinate scale;
T is the time constant of biodegradation of oil products with an adsorbent introduced;
e ≈ 2.718.

 The optimal contaminated soil / adsorbent ratio is selected at the intersection of the graph of the function S (n) with a horizontal line that is 3-5% less than the established value of the function. This ratio is 1: 0.1 (the amount of adsorbent is ≈ 60 t / ha) with a degree of biodegradation of oil products of 68% (see table. 1).

 2. The selection of the optimal range of initial concentrations of oil in contaminated soil for their maximum biodegradation.

 In the table. 2 shows the results of experiments on the biodegradation of oil products in soils with varying initial concentrations of hydrocarbons. In FIG. Figure 2 shows the dependences of biodegradation of oil products at various initial concentrations over time. In FIG. Figure 3 shows the degree of biodegradation of petroleum products after 6 months, depending on their initial concentrations. The area of maximum biodegradation of oil products in the soil is 72-93% and their initial concentration is 290-2500 mg / kg of soil (see Table 2).

 3. The choice of the optimal dose of activated sludge for maximum biodegradation of oil products in the soil.

In the table. 3 shows data on the biodegradation of petroleum products in samples with different concentrations of activated sludge. In FIG. Figure 4 shows the dependences of biodegradation of petroleum products at various initial doses of activated sludge over time. In FIG. 5 shows the degree of biodegradation of petroleum products after 6 months, depending on the initial doses of activated sludge. The dependence of the degree of biodegradation of petroleum products on the dose of activated sludge is described by the formula:
S (d) = k ₁ (1-e ^{-d / Q} ), (2)
where S is the degree of biodegradation of oil products,%;
d is the dose of activated sludge, mg / kg of soil;
k ₁ - scale factor used to calculate the degree of biodegradation of oil products with activated sludge, depending on the scale of coordinates;
Q is the time constant of biodegradation of petroleum products with activated sludge;
e ≈ 2.718.

 The optimal dose of activated sludge is chosen at the intersection of the graph of the function S (d) with a horizontal line shorter by 3-5% of the established value of the function, this dose is ≈ 110 mg of absolutely dry matter (a.s.w.) / kg of soil ( ≈ 0.935 t (a.s.w.) / ha) (see table 3).

 4. The choice of the optimal dose of manure.

The dose of manure introduced into the soil is selected taking into account the vital activity of activated sludge and the further use of land in agriculture. Manure is introduced in an amount of 2-2.5 kg / m ² (17-21.3 t / ha) (see Yurina A.V., Tyuleneva N.A., Kardashina L.A. and others. To help the vegetable grower - amateur. - Sverdlovsk: Sred.-Ural. Kn. Publishing House, 1985, - p. 11).

Thus, the optimal doses of the components introduced into the soil for biodegradation of oil products are, t / ha:
Active sludge (a.s.w.) - 0.85-1.7
Manure - 17-21.3
Adsorbent - 60-65
and the proportion of components in the mixture, wt.%:
Active sludge (a.s.w.) - 1.0-2.0
Manure - 25-35
Adsorbent - 63-67
The activated sludge of sewage treatment facilities of an oil refinery is an association of bacterial microorganisms: Pseudomonas, Ashromobacter, Alcaligenes, Artobacter, Acenetobacter, Rhodococcus, Candida, etc.

As a complex fertilizer, manure, for example, cattle, containing? %:
Organic Matter - 90
Nitrogen - 2-6
Phosphorus (P ₂ O ₅ ) - 1-2
Potassium (R ₂ O) - 0.1-0.6v

Claims (1)

1. The composition for cleaning the soil from oil pollution, containing oil-oxidizing microorganisms, fertilizer and adsorbent, characterized in that as the oil-oxidizing microorganisms use activated sludge from the sewage treatment facilities of the oil refinery, taken from the distribution chamber of the secondary clarifiers after 0 - 8 hours after removal from systems for regeneration, and as fertilizer - manure in the following ratio of components, wt.%:
Active sludge - 1 - 2
Manure - 25 - 5
Adsorbent - 63 - 74
2. A method of cleaning the soil from oil pollution, including treating it with a composition containing oil-oxidizing microorganisms, a fertilizer and an adsorbent, characterized in that the composition uses manure as fertilizer, and activated sludge from a sewage treatment plant of an oil refinery selected from oil refining microorganisms is selected from the distribution chamber of the secondary sumps after 0 - 8 hours after the system is put into regeneration, with the following ratio of components, wt.%: activated sludge 1 - 2, manure 25 - 35, adsorbent 6 3 - 74, once a month they additionally loosen the contaminated soil to a depth of 50 - 55 cm, irrigate the soil with a soil moisture content of less than 50%, and the optimal quantity of contaminated soil / adsorbent n in terms of volume is determined by the formula for the dependence of the degree of biodegradation of oil products S on adsorbent content in contaminated soil
S (n) = k (le ^{-n / T} ),
where k is the scale factor used to calculate the degree of biodegradation of petroleum products with the adsorbent introduced, depending on the coordinate scale;
T is the time constant of biodegradation of petroleum products with an adsorbent introduced;
e ≈ 2.718,
in this case, the optimal ratio of the components is chosen at the intersection of the graph of the function S (n) with a horizontal line shorter by 3 - 5% of the established value of the function, the optimal dose of activated sludge d (mg / kg of soil) is determined by the formula for the degree of biodegradation of oil products S ( %) from the dose of activated sludge
S (d) = k ₁ (1-e ^{-d / Q} ),
where k ₁ , is the scale factor used to calculate the degree of biodegradation of petroleum products with activated sludge, depending on the coordinate scale;
Q is the time constant of biodegradation of petroleum products with activated sludge;
e ≈ 2.718,
in this case, the optimal dose of activated sludge is chosen at the intersection of the graph of the function S (d) with a horizontal line that is less than 3 - 5% of the established value of the function, and the dose of manure introduced into the soil is established taking into account the functioning of activated sludge and further use of soil in the range 2 - 2.5 kg / m ² .

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