RU2217551C2 - Technology to clear marshes from oil and oil products - Google Patents

Abstract

FIELD: environmental protection. SUBSTANCE: technology refers to processes clearing marshes from oil and oil products with high initial concentrations of pollutants, predominantly, during elimination of aftereffects of emergency spillage. Technology is realized by stage by stage clearing of marsh from main and residual concentrations of oil pollution with utilization of weather-climatic factor. At preparation stage polluted lot is divided into sections with the use of dams, trenches to collect oil or oil products are dug along dams. At first stage main concentrations of oil pollution are collected from surface of march during summer-autumn period with the use of lowered floating scraper which executes reciprocation motions with the aid of traction mechanism and travels from one trench to another. At second stage residual concentrations of oil pollution are removed from section of marsh by their wash-off with water stream into trench. In this case beam barrages are installed from one trench to another sideways over cleared section. At third stage polluted top-soil and vegetation layer are removed during winter-spring period, when marsh is frozen, by means of blade-scratcher put on skids by way of its reciprocating movement from one trench to another with the help of traction mechanism. Given technology enables marsh-ridden sections with area up to several hectares to degree of pollution concentration of 500-3000 mg/kg to be cleared and then processes of natural reclamation of soil and vegetation go on successfully. Biological restoration with grass sowing is also possible. EFFECT: improved efficiency of technology. 2 dwg

Description

 The invention relates to the protection of the environment, and in particular to methods for cleaning wetlands from oil and oil products with high initial concentrations of pollution mainly in response to emergency spills.

 A known method of cleaning the water surface of reservoirs and swamps from oil and oil products by means of a self-propelled vehicle with an arrow with a gripping device mounted on it [RU, patent 2123087].

 However, this method can be used in areas with stable soil.

 A known method of cleaning the surface of the soil from oil, including washing the soil with water under pressure and removing the resulting oil mixture [RU, patent 2061144].

 The disadvantage of this method is its use only with minor pollution. In case of emergency oil spills, when the oil concentration is high, this method is ineffective.

 Closest to the claimed invention is a method of cleaning swamps from oil pollution, including dividing the contaminated area into sections and removing oil pollution from the surface of the area using washing it off with a water stream [RU, patent 2142533].

 The specified method is not effective enough for emergency oil spills, when the area of the swamps is several hectares, and does not allow to bring the degree of purification of the wetland to the oil concentration at which natural recovery is possible.

 The present invention is the development of an integrated method for cleaning from oil and oil products of wetlands of large area during accidental spills with a high initial concentration of pollution using the weather and climate factor.

 The technical result consists in cleaning wetlands with an area of several hectares to a degree of pollution concentration of 500-3000 mg / kg, during which the processes of natural restoration of the soil and vegetation cover and bioremediation with grass sowing are successfully underway.

 The technical result is achieved by stage-by-stage cleaning of the swamp from the main and residual concentrations of oil pollution using the weather and climate factor, while at the preparatory stage, the contaminated area is divided into sections by dams along which trenches are collected to collect oil or oil products, at the first the stage collects the main concentrations of oil pollution from the surface of the swamp in the summer-autumn period by means of a buried floating scraper by returning it of translational motion using a traction mechanism from one trench to another, at the second stage, residual concentrations of oil pollution are removed from the site by rinsing it with water flow into the trench, while booms are installed across the site from one trench to another, and at the third stage remove the contaminated soil-vegetable layer in the winter-spring period with a frozen swamp by means of a scraper knife mounted on runners, by its reciprocating movement tions from one trench to another via the linkage.

 The implementation of the method is illustrated by drawings.

 In FIG. 1 shows a diagram of the cleaning of a swamp site from basic concentrations. In FIG. 2 shows a knife-scraper (in section).

 The wetland area flooded with oil during the accident (Fig. 1) is divided into sections (1) using sand dams (2). The length and width of the section is determined by the convenience of subsequent work. Along the dams (2) dig trenches (3) with a depth of 1 m or more to collect oil and oil sludge. The first stage of purification from basic concentrates is carried out preferably in the summer. On both sides of the section (1), on the dams (2) there are two traction mechanisms (4) - tractors with winches (5) mounted on them, which are connected to the floating scraper (7) via a cable coupling device (6). The scraper (7) is made in the form of a pipe or pipe connection with hermetically sealed ends. The scraper (7) is deepened into the oil layer by increasing its weight by filling the volume with liquid or granular material through the plug (8). Using winches (5), the scraper (7) is moved from one trench to another. The oil captured by the scraper (7) is transported to the trench (3). Then both traction mechanisms (4) move along the dams (2) in the same direction by a distance equal to about half the length of the scraper (7), and the process repeats. Area (1) is cleaned until all oil that can be collected by the scraper (7) is removed from the surface. From the trench (2), the collected oil is transported to a temporary storage pit for subsequent processing. After the first stage is over, oil residues and contaminated plant residues remain on the surface of the swamp.

 During the same summer-autumn period, the second stage of cleaning the swamp from residual concentrations is carried out. For this, section (1) is washed with water under pressure from mobile high-performance pumps, creating a flow towards the trench (3). Washed residual oil contaminants with a water stream are transported to a trench (3), from where they are transported to temporary storage for subsequent separation of oil and water and processing of oil sludge. If necessary, booms can be installed across the site to create a larger flow of water.

 In winter, the swamp freezes to a depth of several tens of centimes, and the soil contaminated with oil remains unfrozen, the oil remaining on the surface becomes thick. The third stage of cleaning is carried out at the beginning of winter or in the spring after snow melt.

 The technological scheme of the third stage of the final cleaning of the site from contaminated plant residues and the soil and plant layer is similar to the scheme for cleaning from basic concentrations and differs in that a knife-scraper is used instead of a floating scraper (7, Fig. 1).

 The scraper knife (Fig. 2) is mounted on skids (9), the working body is made in the form of two knives (10) fastened together, on both sides of the working body, fences (11) are made to hold sludge during transportation.

 Using winches, a knife-scraper is moved from one trench to another. Cleaning is carried out until the complete removal of the contaminated soil and plant layer. The collected oil sludge is taken out for further processing.

 To remove the contaminated layer in a very frozen swamp (freezing depth of 70-90 cm), the final cleaning can be done with a swamp bulldozer with a low specific surface pressure.

Example
A marshy swamp of 30 hectares was divided into sections by sand dams. The length of the section was equal to the length of the swamp, and the width was 60-70 m. Trenches 1 m deep were dug along the dams. The height of the oil layer above the soil was 50 cm. The depth of soil impregnation was 50-70 cm. The first stage of cleaning was carried out according to the technology described above. A floating scraper with a diameter of 72 cm was buried in the oil layer. At one time, a scraper transported from 5 to 10 m ^{3 of} oil to the trench. On average, over 9 hours of work, they cleared areas with a total area of 2 hectares. After the first stage, the residual oil pollution and oil-contaminated plant debris remained on the surface of the swamp, the oil concentration in the soil averaged 250,000 mg / kg.

Then, the swamp was cleaned of residual concentrations. The section was divided by booms at a distance of 5-7 m from each other. Mobile high-performance 6-inch pumps and fire brigade pumps were used to flush residual concentrations and create a flow towards the trenches. Operators moved along wooden floors and streams of water at an angle of 5-10 ^o to the surface of the swamp washed off the residual oil pollution in front of them, which rushed to the trenches with a stream of water. After the second stage was completed, the oil concentration in the soil was 50,000-60000 mg / kg.

 The third stage of cleaning was carried out in the spring after snow melting in a frozen swamp.

 After the third stage, the pollution concentration was 500-3000 mg / kg. In the spring, bioremediation works were performed on the cleaned area, and the restoration of the soil and vegetation cover was successful.

 Thus, an integrated method for cleaning wetlands during emergency oil spills allowed the restoration of an area of 30 hectares.

Claims (1)

A method of cleaning swamps from oil and oil products, including dividing the contaminated part of the swamp into sections and removing oil pollution from the surface of the site using rinsing with a water stream, characterized in that the swamp is gradually cleaned of the main and residual concentrations of oil pollution using the weather and climate factor at the same time, at the preparatory stage, the contaminated site is divided into sections by means of dams along which trenches are digged to collect oil or oil products, at the first stage, the main concentrations of oil pollution are collected from the surface of the swamp in the summer-autumn period by means of a buried floating scraper by means of its reciprocating movement using a traction mechanism from one trench to another, at the second stage, residual concentrations of oil pollution are removed from the site by washing it off with a water stream into the trench, while booms are installed across the section from one trench to the other, and at the third stage they are removed contaminated soil-vegetable layer in the winter-spring period with a frozen swamp by means of a knife-scraper mounted on runners, by its reciprocating movement from one trench to another using a traction mechanism.

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