RU2241555C2 - Method for recultivation of soil contaminated with petroleum and petroleum products in winter - Google Patents

Abstract

FIELD: environment protection, in particular, recultivation of petroleum contaminated soil.

SUBSTANCE: method involves fixing petroleum spot by means of natural sorbing material, such as peat containing petroleum decomposing microorganisms and mineral feeding elements, with hydrophobizated highland and lowland peat being used in the weight ratio of 4:1 and granulated to produce granules of 5 mm diameter and 10 mm length and said granules being saturated with psychrotolerant petroleum oxidizing microorganisms separated from emergency site; applying granules onto petroleum spot at the rate of 1 kg per 6-13 kg of petroleum depending on environment temperature. Method allows petroleum to be bound and prevented from spreading over soil surface, as well as from penetration into soil lower layers upon thawing. Psychrotolerant petroleum oxidizing microorganisms available in sorbent provide for petroleum decomposition at reduced positive temperatures.

EFFECT: increased efficiency by binding petroleum and, accordingly, reduced volume of contaminated soil during emergency petroleum overflow.

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Description

The present invention relates to the protection of the environment, in particular to the restoration of soils contaminated with oil and oil products in the winter.

There is a method of reclamation of post-technogenic and remote territories in the Far North (RV patent No. 2093974 A 01 B 79/02, 1997), which includes applying organic fertilizers to the soil and sowing perennial grasses in one step, and fertilizing and sowing material is produced in spring and / or in the fall on thawed or frozen soil.

This reclamation method cannot be used in the winter period.

A known method of reclamation of soils contaminated with oil (RV patent No. 2038363 C 09 K 17/00 A 01 B 79/02, 1995), including plowing the soil, the application of organic and mineral fertilizers, a structuring agent and ameliorant, as well as sowing of herbaceous plants.

The method is not applicable for winter conditions.

A known method of reclamation of soils contaminated with oil and oil-containing products (RV patent No. 20099626 A 01 B 79/02, 1994), including the collection of oil and oil products, applying a layer of organic sorbent - peat, the implementation of planting of wild game on a peat-covered surface of contaminated soils plants with a lump of land in the pits.

The method is not applicable for winter conditions.

As a prototype, the invention RV patent No. 2104103 B 09 C 1/10, C 02 F 3/34, C 12 N 1/20, 1998, where peat was used to clean the soil from oil and oil products, was crushed and heat treated to bulk density 0.09-0.13 g / cm ³ . Peat contains humic acids in an amount of 20-30 wt.%. After applying peat, an additional aqueous suspension of hydrocarbon-degrading bacteria from the genus Rhodococcus is added, containing salts of nitrogen, phosphorus and potassium. Peat consumption is 0.3-0.7 kg per 1 kg of pollutant, the consumption of aqueous suspension is 8-12 kg / m ² surface.

This method of soil remediation cannot be used in the winter period, because the use of an aqueous suspension is provided, which is impossible at low temperatures. In addition, the method is expensive, because high consumption of peat and suspension.

The objective of the invention is a cost-effective way to restore oil-contaminated land in the winter.

This problem is solved due to the fact that the oil slick is fixed with a natural sorbing material - peat containing oil-polluting psychrotolerant microorganisms and elements of mineral nutrition.

New is that hydrophobized peat is formed into granules with a diameter of 5 mm and a length of 10 mm. The results of our scientific studies have shown that granules of this size are held on the surface of viscous oil, are not blown away by the wind, drown in an oil slick, and have the highest sorption capacity. One kilogram of granules accumulates 6-13 kg of oil, depending on the ambient temperature.

New is the fact that for the production of granular peat, peat and lowland peat are used in a ratio (weight) of 4: 1. Peat peat has a high sorption capacity, lowland peat contains humic substances with adhesive ability. This combination of two types of peat in a ratio of 8: 2 allows you to form a durable granule with high oil capacity.

The technology for granule production includes operations to saturate the biosorbent with active psychrophilic destructors of oil and oil products, elements of mineral nutrition and lime.

The method was tested at the enterprises of Transneft with a positive result.

Example:

The production experience in testing the “Method for the remediation of soils contaminated with oil and oil products in the winter time” was laid on April 1, 2002 on the territory of the Torgili LPDS of the Tyumen UMN.

After laying the field experiments, the spread of the oil slick was measured during the first day. The experimental site had a slight bias in the north, so this area was subjected to more pollution. In the variant without a fence, the oil slick on the north side spread to an area of 1.67 m ² (table 1).

A territory of 0.38 m ^{2 was} polluted with oil on the south side, 0.93 m ² on the west, and 0.72 m ² on the east. The total area of oil distribution was 3.7 m ² .

The introduction of a biological sorbent on the spilled oil allowed a sharp reduction in the area of pollution. After removing the fence from this option, oil flowed northward to an area of 0.32 m ² , in the south - to 0.19 m ² , in the west - to 0.13 m ² , in the east - to 0.12 m ² . The total area of the spreading oil amounted to 0.76 m ² , which is 4.8 times less in comparison with the option where no sorbent was used.

In production experiments, peat granules were applied to the oil slick immediately after the spill, which allowed the accumulation of a significant part of the oil and prevent its further spreading. This material shows the effectiveness of using granular peat as a sorbent substance in order to prevent its spreading.

In fenced versions, oil also spread beyond the boundaries of the carcass, as the soil had a sandy structure. When using biogranules, the area of contamination was 0.4 m ² , and in the absence of them in the plots, oil spread over an area of 1.07 m ² .

Depth of penetration of oil.

The experiment was laid on frozen soil, so the first measurements of the depth of oil penetration were carried out in mid-May. By this time, a 10-15 cm layer of soil had thawed. In cases without the use of a biological sorbent, oil seeped down the profile by 12.7-15.2 cm (table 2). The addition of granular peat to the spill allowed sorption of oil, which prevented not only spreading over the surface of the soil, but also its penetration deep into. In options with biogranules, the oil saturated the topsoil of 6.1-6.3 cm.

The second measurements of changes in the depth of oil penetration were carried out in early June. As the lower horizons of the soil thawed in areas where granular peat was not added, further pollution of the lower horizons was noted - oil leaked to a depth of 21.4-26.5 cm. In the plots using a biologically active sorbent, further penetration of the oil deeper into the soil during thawing was insignificant and amounted to 1.4 cm.

Thus, the experimental results show that the use of hydrophobized granular peat of certain sizes binds oil and prevents it from spreading both on the soil surface and deep into the profile, thereby reducing the amount of pollution during accidental spills.

Change in the concentration of oil and oil products under the influence of a biological sorbent.

The production experience in testing the effectiveness of the technology for the restoration of oil-contaminated lands in winter using indigenous psycho-tolerant microorganisms of oil destructors was completed on June 14, since by June 1 almost all oil was destroyed at experimental sites with biogranules.

The initial level of contamination was 181.3-201.4 g / kg of soil (table 3). Under the influence of natural factors, oil decomposed only 11-20%. Psychrotolerant hydrocarbon-oxidizing bacteria applied to granular peat a month after they were added reduced the oil concentration from 181.3 to 67.2 g / kg, and by June 1, 85% of the oil had degraded.

Thus, the results of industrial tests of the method of reclamation of oil-contaminated lands in the winter period showed the prospects of this area. The use of a biologically active sorbent of a certain quality and size on emergency winter spills accumulates oil and prevents its spreading with increasing air temperature. The area of the spreading oil in the version with biogranules was 4.8 times smaller in comparison with plots where the sorbent was not used.

The introduction of a granular sorbent of a certain size and composition on an oil slick effectively binds oil and, when thawing the soil, prevents its penetration into lower horizons. In the variant without the use of peat granules, the soil layer of 17-20 cm was contaminated, in the plots with biogranules - a layer of 7 cm.

The presence of psychrotolerant oil-oxidizing microorganisms in the peat sorbent ensures the destruction of oil at low positive temperatures. The content of oil and oil products in April under the influence of a biologically active sorbent decreased 2.7-3.6 times, and by June 1, oil had decomposed by 85%.

Claims (1)

The method of reclamation of soils contaminated with oil and oil products in the winter time, including the application of sorbent material to an oil slick with microorganisms - destructors and mineral nutrition elements, characterized in that the hydrophobized upland and lowland peat in the ratio by weight 4: 1 is formed into granules with a diameter of 5: 1 mm, 10 mm long, which are applied to the oil slick at a dose of 1 kg per 6-13 kg of oil, and the granules are saturated with psycho-tolerant oil-oxidizing microorganisms isolated from the accident site.