RU2294804C2 - Method for clearing and recultivation of soil contaminated with petroleum and petroleum products - Google Patents

Abstract

FIELD: agriculture and ecology, in particular, process used for recultivation of soil subjected to contamination with petroleum and petroleum products.

SUBSTANCE: method involves introducing microorganisms into soil; providing spring or autumn plowing of contaminated soil to 35-50 cm depth, with humus and mineral fertilizers being introduced before plowing procedure; harrowing to 20-40 cm depth so as to turn soil to the outside; planting native kinds of seedlings of woody plants and bush sprouts into furrow bottom by numerically mixing thereof; before planting, processing plants with laser radiation. Before planting of seedlings or sprouts into furrow, microorganisms are introduced into soil by dipping of root system into aqueous solution saturated with microorganisms separated from soil of the same region which had been earlier contaminated with petroleum.

EFFECT: intensified process for recultivation of soil contaminated with petroleum or petroleum products.

2 cl, 2 tbl, 1 ex

Description

The invention relates to agriculture and ecology and can be used for reclamation (phytoremediation) of soils susceptible to contamination by oil and oil products.

In areas of oil production, spill, pumping and refining, emergency situations periodically occur, leading to oil and oil products contamination of soils and water bodies in adjacent territories, which causes great damage to nature. As a result, there is a need to eliminate the consequences of the above technological disasters.

There are many ways to clean the soil, which can conditionally be divided into the following main areas:

The first direction is the complete removal of contaminated soil outside the site with its subsequent cleaning.

Removal is carried out in various ways, including, as a rule, mechanical; for cleaning the removed soil, it is recommended to extract oil with organic solvents or the biochemical decomposition of oil hydrocarbons by soil microorganisms (see, for example, Russian patents Nos. 2061144, 2142533, 2177843 and others).

The second direction is cleaning at the spill site.

It is based on the ability of the soil to self-clean due to the evaporation of the volatile fraction of contaminants, leaching, atmospheric oxidation under the influence of solar radiation and biodegradation.

With a small content of oil hydrocarbons in the soil, the simplest method can be applied - it is periodically plowed to mix and aerate the scattered contaminated waste material through the soil with a thin layer. At the same time, hydrocarbons decompose soil microbes.

On-site cleaning is accelerated by the introduction of fertilizers into the soil that nourish the microorganisms present in the soil, by additionally introducing various strains of microorganisms and bacteria with the ability to biologically process and destroy oil and oil products, and also by applying other organic absorbents (see, for example, patents Russia No. 2198748, 2007372, 2104248, 2112610, 2137559 and others).

All existing methods provide for an active effect on contaminated soil (mechanical loosening, milling, washing with water under pressure, cutting and removing a heavily contaminated layer, applying significant doses of mineral fertilizers, etc.) without taking into account the genesis, composition, and properties of a particular type of soil.

In fact, the process of elementary dilution of oil concentrated in the upper 5-10 cm layer occurs due to the underlying layers. This leads, firstly, to the movement of microorganisms located on the surface in depth, and secondly, a significant part of the oil complexes gradually migrate upward with water, increasing its concentration in the post-remediation period up to the level of phytotoxicity.

When introducing strains and microbiological preparations, the main disadvantage is their selective effect.

Closest to the claimed one is a method for cleaning and reclamation of soils contaminated with oil and oil products (see patent No. 2217246, publ. 01.20.2001), which consists in treating the soil with preparations containing oil refining bacteria, together with biodestructors of the next trophic level - earthworms . This speeds up the process of movement and spread of bacteria due to the transfer by worms along the perimeter and in depth on its surface and in the intestine of microbiological preparations. In addition, the access of oxygen to the deep layers of oil-contaminated soil is facilitated.

Although this method makes it possible to activate the destruction of oil pollution by microflora, as well as to promote soil restoration due to the formation of biohumus worms during the life process, which improves the soil structure, complete cleaning in this way (to an acceptable concentration) requires a fairly long time (it may take years) and, in addition, the problem of restoring soil characteristics to a level that ensures the growth of higher plants is not being solved.

An object of the invention is the unification of the method, i.e. the possibility of its effective use in any climatic zones and on any type of soil, while ensuring complete purification to the maximum permissible level and balancing the natural environment subjected to anthropogenic impact, as well as restoring the natural landscape and improving the ecological situation in the region as a whole.

The specified problem is solved as follows.

The method of cleaning and reclamation of soils contaminated with oil and oil products by applying microorganisms to the soil additionally includes spring or autumn plowing of contaminated soil to a depth of 35-50 cm with humus and mineral fertilizers applied before plowing, plowing to a depth of 20-40 cm with a spread (dump) of soil outward, planting into the bottom of the furrow of woody and shrubby plants by their orderly mixing (interspersed). For each locality, native breeds of plants are chosen, and before planting, the plants are treated with a laser (laser beam), and their root system is immersed in a solution saturated with microorganisms taken from a regional microorganism bank created in each region potentially dangerous from the point of view of oil pollution by isolating strains of microorganisms from the soils of the region previously exposed to oil pollution.

The technical result of the invention is to accelerate the process of reclamation due to tree-shrubbery vegetation, mutually supporting and strengthening one another, the root system of which contributes to the formation of rhizospheric microflora, which has a high potential for soil purification, restoration of soil characteristics to a level that allows the growth of higher plants.

Examples of the method.

On a site of 0.8 hectares in the Kushchevsky district of the Krasnodar Territory as a result of damage to the pipeline at the end of the spring period, oil pollution occurred, which in some places amounted to 57 g of oil products per 1 kg of soil. In the autumn of the same year, agricultural work was carried out on the site - plowing the soil to a depth of 40 cm and subsequent furrowing to a depth of 30 cm with a turn (dump) of soil to the outside. For planting, tree seedlings (over 2 years) of various willow species (goat, white, Babylonian), poplar and aspen, i.e. "Pioneer breeds" and seedlings of shrubs: macular, rose hips and privet.

Before digging from the soil of the nursery, seedlings and seedlings were laser treated. A helium-neon laser with a wavelength of 632.8 nm and a power of 25 mW was used. Laser treatment was performed within 4 days after sunset, which, as is known from the literature, helps to stimulate the root system and accelerate its development. For all types of seedlings and seedlings under conditions of dense planting in the nursery, the same laser processing parameters were used: processing time 5-6 minutes, pulse frequency 5 Hz.

After digging, the roots were soaked for 30-40 minutes in an aqueous solution containing strains of microorganisms isolated from similar soils in the region, on which oil was previously bottled, for better survival.

Then they were densely (given the difficult survival conditions) planted alternately tree-shrubs, etc., into the bottom of the furrow, and their arrangement in adjacent rows was mainly carried out in a checkerboard pattern to ensure further coverage of the entire area with the root system. The rows were predominantly formed as follows: willow-privet, poplar-maclura, aspen-rosehip. The planting density was in the row 0.5 m, the row spacing was 1.5 m.

In the same area for control, plants were planted that were not subjected to preliminary laser treatment.

Survival data and changes in growth indicators after a year for various plant species are given in tables 1 and 2.

Table 1.
The survival rate of plants to the total number of planted (in%). Type of plant Unprocessed laser Laser treated Poplar 78.8 98.2 Willow 96.0 one hundred Aspen 63.3 96.6 Dogrose 73.3 93.3. Maclura 25.8 32.8 Privet 25.3 31,0

Table 2.
The increase in growth parameters of laser-treated plants over the year in comparison with untreated (in%). Type of plant Plant height increase Increase the length of the main root Poplar thirty fifty Willow 32 54 Aspen 27 48 Dogrose 33 40 Maclura thirty 37 Privet 28 33

Thus, from table 1 it can be seen that the survival rate of all plants subjected to laser treatment is higher than that of untreated plants. And the data shown in table 2 confirm the effectiveness of laser processing to increase both the underground and above-ground mass of plants.

At the same time, after a year, the oil content in the soil decreased to 20 g per 1 kg of soil, and after 2 years it reached 0.7 g per 1 kg, i.e. the oil concentration became lower than the maximum allowable component of 1 g per 1 kg of soil. In the future, this place will be a park area.

This result was achieved due to the fact that the root system of woody and shrubbery plants enters cleaner soil layers, because contaminated as a result of furrowing with a turn of the layers to the outside, they appear on the surface (in dumps). Alternating planting in rows of trees and shrubs allows you to cover almost the entire space of the soil with an extensive network of root systems.

Claims (2)

1. The method of cleaning and reclamation of soils contaminated with oil and oil products by introducing microorganisms into the soil, characterized in that it additionally includes spring or autumn plowing of contaminated soil to a depth of 35-50 cm with application of humus and fertilizers before plowing, furrowing to a depth of 20- 40 cm with the soil turning outwards, planting seedlings of woody seedlings and shrubs of seedlings of bushes of indigenous species by orderly mixing, and before planting, the plants are treated with a laser and applied to the soil microorganisms is performed by dipping the root system of the plants before planting furrow in an aqueous solution saturated with microorganisms isolated from soil of the same region, previously subjected to oil contamination. 2. The method according to claim 1, characterized in that willow seedlings of willow, poplar, aspen are planted as woody plants, and rose hips, privet, and macula as shrub plants.