RU2309808C2 - Method for purifying soil polluted with petroleum products - Google Patents

Abstract

FIELD: ecology, soil pollution.

SUBSTANCE: the present innovation deals with liquidation of petroleum-caused soil pollution as a result of unsanctioned spreading petroleum and petroleum products over the ground to be applied for reconstructing soil properties after contamination. The method consists of sampling polluted soil followed by its treatment for purification against petroleum products to be returned to the place of sampling or other place with similar ground structure. Selected contaminated soil should be steamed at addition of soda and surface-active substances. Steamed soil should be mixed with peat and fertilizers, then the mixture obtained should be supplemented with petroleum-oxidizing aerobic microorganisms and this prepared mixture should be placed into a biodrum to treat at constant mixing at addition of heated air, and due to keeping the temperature of the mixture under treatment being not less that 16°C for about 1-2 d. After that the mixture should be removed out of the biodrum for covered storage for the period of about 2-3 mo followed by returning the treated soil to the desired place. The innovation increases the output of purified ground, excludes the application of complicated constructive equipment and simplifies the technology for soil purification.

EFFECT: higher efficiency of soil purification.

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Description

The invention relates to the field of elimination of oil pollution of soils formed as a result of unauthorized bottling of oil and oil products on the ground, and can be used to restore the properties of soils subjected to pollution.

A known method for the continuous separation of oil-containing soil, including obtaining a suspension by dissolving the soil to be cleaned in a liquid medium, feeding the suspension into a continuous flow apparatus for treating the suspension with a pulsating force field, representing low-frequency vibration effects in resonance or near-resonance mode with a frequency range of vibration of 10-60 Hz and acceleration 3 - 20 g, and the processing of the suspension in the apparatus is carried out in a gas-liquid medium created by the supply of gas to the flow apparatus an amount of 10-25% of the treated suspension.

(see RF patent 2139143, 03/13/1998) - the closest analogue.

As a result of the analysis of the known invention, it should be noted that the method disclosed above is based on the mechanical separation of soil and its polluting components, which requires significant energy consumption and the use of devices with rather complex kinematics, and in addition, the known method is characterized by significant waste of processed (cleaned) soil in connection with the impossibility of separating the components of the soil that have reacted with each other and the oily waste.

The objective of the present invention is to develop a method of cleaning the soil, which can dramatically increase the yield of purified soil, eliminating the use of complex structural devices and thereby simplify the cleaning technology.

The task is ensured by the fact that in the method of cleaning soil contaminated with oil products, including the selection of contaminated soil, followed by its processing for cleaning from oil products and returning to the place of selection or another place with a similar soil structure, new is that the soil selected from the contaminated area steamed with the addition of soda and surfactants, the steamed soil is mixed with peat and fertilizers, after which oil-oxidizing aerobic microorganisms are added to the resulting mixture and prepared the mixture is placed in a bio-drum, in which the mixture is processed with constant stirring with the supply of heated air, maintaining the temperature of the processed mixture at least 16 ° C for 1-2 days, after which the mixture is removed from the drum and kept for 2-3 months then return the treated soil.

When conducting patent research from the prior art, no solutions were found that are identical to the claimed invention, and therefore, the claimed invention meets the patentability condition of "novelty."

The essence of the claimed solution does not follow explicitly from the prior art, and therefore, meets the condition of patentability "inventive step".

The information set forth in the application materials is sufficient for the practical implementation of the invention by specialists.

The method of cleaning soil contaminated with oil is as follows.

Before carrying out activities related to phyto-correction of the soil, the contaminated area is initially delineated. If there are liquid hydrocarbon components on the surface of the site, they are removed in a known manner.

The contaminated soil layer (layer) is removed and the type and concentration of hydrocarbons and other harmful substances contained in it are determined, and then the remote contaminated soil is steamed. Steaming is carried out with hot water or steam under pressure using soda and surfactants. To increase the convenience of processing, the soil can be loaded into self-opening containers and can go through a treatment cycle without being removed from the containers, which greatly simplifies the process of loading and unloading the soil during its cleaning.

Steaming the soil allows you to remove paraffin-like components and excess water from it. The steaming is carried out in a container reactor, where self-opening containers with processed soil are loaded.

After steaming, determine the pH of the soil and the content of hydrocarbons in it and, if necessary, re-treat the soil with soda.

The design of containers for placing the soil to be cleaned and the container reactor are known and there is no need for a detailed description thereof.

The dehydrated and pre-cleaned soil is mixed with peat, mineral and biological fertilizers are added, and oil-oxidizing aerobic microorganisms are added to the resulting mixture (for example, using equipment and methods of Nika, St. Petersburg).

Next, the resulting mixture, representing the cleaned soil, fertilizers, peat and microflora, is loaded into a bio drum. The design of the bio-drum is known and does not constitute the subject of patenting. The mixture is usually fed to the bio-drum by a feeder.

Processing the mixture in a bio-drum is carried out with a constant rotation of the latter, which ensures mixing of the mixture into a uniform single mass.

In the process of processing the mixture in a biochamber to activate the biological processes taking place in the mixture, air preheated to 35-45 degrees is fed into the free space of the bio-drum.

The mass of the mixture loaded into the bio-drum for each processing cycle is determined using a conveyor scale and a time relay.

Temperature control and temperature control of the treatment inside the bio-drum is carried out by means of temperature sensors installed in the volume of the bio-drum, the signals from which are fed to the air supply control panel in order to control its temperature.

As studies have shown, for the stability of the flow in a mixture placed in a drum of chemical, biochemical and physico-chemical processes, the temperature of the mixture in the bio-drum should be maintained at a level of at least 16 ° C for 1-2 days.

From the point of view of chemical reactions in the process of biothermal treatment, the oxidation of the main elements of oil occurs through oxygen, which is part of the mixture being cleaned, and air supplied to the bio-drum.

Under ideal conditions, biothermal treatment - an aerobic process and the complete oxidation of elements of organic matter - leads to the formation of carbon monoxide (CO ₂ ) and water (hydrogen oxide).

As studies have shown, the need for air to ensure the occurrence of oxidative reactions is approximately 7.0-8.0 m ³ / h per 1 ton of mixture.

Oil decomposes as a result of the activity of oil-oxidizing saprophytic aerobic microorganisms capable of generating a certain amount of heat during biochemical metabolic reactions. The creation of the best living conditions for microflora is created by increasing the specific surface area of particles by mixing oil-contaminated soil with peat, air supply, creating a porous structure by constant mixing, maintaining the moisture content of the mass within 45-60%, and thermal insulation, which helps preserve the released heat.

During the processing of the mixture in a bio-drum, accelerated multiplication of mesophilic microorganisms is observed. Easily degradable organic compounds contained in peat or oil are the source of energy for bacteria. In the process of their life, thermal energy is released, which contributes to the heating of the soil and the development of thermophilic microflora.

After the set processing time has elapsed in the bio-drum, the mixture is removed from the container, stacked at the site and stacked. In the process of development of thermophilic microflora, soil temperature rises to about 70 ° C. In this case, the decomposition of organic matter is sharply accelerated.

When in stacks, the temperature of the soil gradually decreases, which indicates the oxidation of the decomposable part of the organic matter. At this stage, the thermophilic microflora passes into a spore form, partially dying, and the mesophilic begins to multiply again. Given that it has a more developed and powerful enzymatic system, its ability to decompose the most persistent organic compounds (fiber and lignin) increases.

Before the complete "ripening" of the soil on the site should pass at least 2-3 months.

Next, the cleaned rock is transported and placed in the place from which it was removed, or in another place with a similar soil structure.

The main parameters of the claimed method are given in table 1.

Recommended additives are given in table 2.

Table 1. Technological process parameters and their tolerances Technological parameters unit of measurement Technological parameters optimum fluctuations one 2 3 four Soil weight kg 2000 1000-3000 Specific gravity t / m ³ 1.8 1.2-2.2 The size of mineral inclusions mm no more than 100 - Oil pollution % twenty 10 Organic matter content % to dry weight more than 5% to 10% Humidity % less than 50 ± 20 Soil temperature ° C not lower than 0 ° С from 0 ° С to + 30 ° С Loading dose t / day 12 + 30% Boot mode t cyclic, 2 t every 4 hours cyclic 20% Number of reactors PC 1-3 not limited Execution of reactors and settling tanks modular, sea containers The amount of washed oil t / s not regulated not regulated The mass of washed soil in a bio-drum t 12 2 The mass of biofertilizers t / t 0.01 Peat mass t / t 0.5 The mass of mineral fertilizers t / t 0.003 Air temperature for aeration ° C 35 - Time of processing day no more than 1 - Process Unloading Mode t at boot time - Bio-drum annual production * thousand tons / year 32,0 ± 10% Number of working bio-drums PC. not limited - The dose of loading the substrate with microflora * t / day 1-3 ± 20% Microflora substrate loading mode * t cyclic 0.17-0.51 Cyclic ± 20% Note * - indicators are given per one reactor and one bio-drum-mixer.

table 2 Norms for the application of biological products, mineral and biological fertilizers Type of drug Application rate, kg / t Notes Peat 100-500 Depending on the amount of humus Gypsum 5-15 PH dependent Fertilizers Potash 100-300 Depending on soil type Nitrogen 100-300 Depending on soil type Phosphoric 100-300 Depending on soil type BAG 1-3 Grass seeds 20-60 g Depending on the type of grass and soil type Biological products Manufacturer: Roder MSU Petrolan NTO "Priborservis" Station wagon 1-3 Institute of Biology RAS Institute Lignosorbent 1-3 Biology RAS Bamil 1-5 Nika, St. Petersburg Dekonta 1-5 Czech Putidul 1-5 ZapsibNIGNI (Tomsk) Devoroil 1-5 NPP Biotechinvest (Moscow) Bioprin (Olevorin) 1-5 VNII Sintezbelok (Moscow) Note: the norms specified in the instructions for use are recalculated from the calculation: 1 ha corresponds to 1000 tons of soil

All other elements of the biofermentation system are made from conventional, widely used materials.

Claims (1)

The method of cleaning soil contaminated with oil products, including the selection of contaminated soil with its subsequent processing for cleaning from oil products and return to the place of selection or another place with a similar soil structure, characterized in that the soil selected from the contaminated area is steamed with the addition of soda and surfactants , steamed soil is mixed with peat and fertilizers, after which oil-oxidizing aerobic microorganisms are added to the resulting mixture, and the prepared mixture is placed in a bio drum, in which they start processing the mixture with constant stirring with the supply of heated air, maintaining the temperature of the processed mixture not lower than 16 ° C for 1-2 days, after which the mixture is removed from the drum and kept in herds for 2-3 months, after which the processed the soil.