Oil sludge and their impact on the environment

ABSTRACT

The article examines the sources of the formation of oil sludge, their component composition and content, their maximum permissible content in the soil, at which the manifestation of the destructive effect of the specified toxicant on soils and flora is not expected. The classification of oil wastes, recommendations for preventing their impact on the environment, especially such components as heterocyclic, polyaromatic compounds and heavy metal ions are given.

АННОТАЦИЯ

В статье рассматривается источники образования нефтешламов их компонентный состав и содержание, максимально допустимые содержания их в почве, при котором не ожидается проявление губительного действия указанного токсиканта на почвы и растительный мир. Приводится классификация нефтяных отходов, рекомендации по предотвращению воздействия их на окружающую среду, особенно такие компоненты как гетероциклические, полиароматические соединения и ионы тяжелых металлов.

Keywords: oil sludge, oil refineries, oil-contaminated soils, sludge collectors of ground, bottom and reservoir types.

Ключевые слова: нефтешлам, нефтеперерабатывающие заводы, нефтезагрязненные грунты, шламонакопители грунтового, придонного и резервуарного типов.

One of the significant sources of environmental pollution is oil sludge, which is formed both in the process of oil production and in the process of oil refining.

Solid waste includes bottom sediments of tanks, drill cuttings, drilling mud, oil sludge from spills, oil sludge from oil refining and pipeline oil sludge.

The classification shows that oil refining sludge is classified as oil and gas industrial waste and requires an individual approach to their processing.

At oil refining enterprises, a large amount of waste is generated during storage, processing of oil and oil products, washing of technological equipment, steaming of railway and road tankers. Depending on the method of their formation, oil sludge is divided into groups: ground, bottom and reservoir type. Ground oil sludge is formed when oil products are spilled onto the ground in emergency situations or during production. One of the reasons for the formation of oil sludge in tanks is the physicochemical interaction of oil products with the metal of the tank, water, oxygen and mechanical impurities.

Oil is delivered to refineries in storage tanks. According to the design standards, the production reserve for supplying the plant via the oil pipeline should be three days. During storage, the oil stratifies, and oil sediments settle to the bottom of the tank.

Oil sludge, oil-contaminated soils, sand stored in special storage tanks are called oil sludge accumulators.

The composition and characteristics of oil sediments depend on the properties of the oil. In terms of composition, oil sludge is a stable multicomponent formations consisting of organic, aqueous parts and a mineral part in the form of sand, silt, metal oxides, etc.

Oil sludge, oil-contaminated soil, sand are stored in special sludge collectors, which leads to environmental pollution and oil losses.

The stability of such systems greatly increases with their long-term storage in open barns and ponds. This happens due to the "aging" of emulsions, compaction and hardening in time of armor shells on water drops, evaporation of light fractions, tarring of oil products, an increase in mechanical impurities due to atmospheric dust, etc.

Studies carried out in the area of storage pits showed: the presence of filtration from the pits through the underlying bottom of loam at a rate of about 0.05 m / day; increase of mineralization in groundwater by 350 times and the amount of oil products by 6-12 times in the period from 1975 to 1995; increase in the area of pollution from the system of barns due to the factor of spreading groundwater; the presence of evaporating hydrocarbons in the air above the surface of barns in concentrations of 0.1-27 mg /m³, the emission of which is 120 t / year of the total volume. It has been established that when the barns are removed from the degree of exploitation of water resources, although reduced, it remains high even after 10 years.

Table 1.1

Composition of oil sludge from production and processing

Long-term storage of oil sludge in barns, which often exist for decades since the beginning of field development, and do not meet modern environmental requirements, leads not only to the withdrawal of land, but also to emissions of pollutants into the atmosphere as a result of evaporation of light fractions; filtration into underground aquifers through the sides and base of the storage tanks; violation of dumping of waste storage facilities and dumping waste water on the terrain; death of migratory birds and animals.

Oil sludge from oil refineries is the bottom sediments of all mechanical wastewater treatment facilities, products of tank cleaning, flotation concentrate of cascade-adhesive separation units for flotation machines. In general, this is a thick, viscous paste-like mass, quite heavily watered (water content of 20-70%). It also contains an average of 20-75% of petroleum products and 5-10% of mechanical impurities in the form of abrasive or metal dust, sand.

It can be noted that the processing sludge contains more of the hydrocarbon part in comparison with the drilling slime, which emphasizes the need to return them to the resource circulation.

 The article shows that the maximum content of oil waste in the soil should not exceed 0.1 g/kg of soil. In this case, the harmful effect of this toxicant on the soil is not expected, and mutogenesis is not observed in the plant community. Thus, it is clear from the presented data that oil-containing waste is extremely dangerous for natural systems. It follows that it is necessary to strictly control the content of oil sludge in the environment, and when placing such waste, special attention should be paid to the content of such toxic components as heterocyclic, polyaromatic compounds, and heavy metal ions.

List of references:

1. Zhumaev K., Tursunov B., Shomurodov A., Mukhiddinov J. Effect of oil sludge on the environment. Science and education.  February 2021 / Volume 2   Issue 2, 115-120 p.
2. Zhumaev K., Tursunov B., Shomurodov A.,  Maksudov M.  Analysis of the accumulation of oil sludge in warehouses. Science and education.  February 2021 / Volume 2   Issue 2, 181-185 p.