RU2629786C1 - Method for purifying stagnant reservoir under conditions of continuous ingress of oil products - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method is carried out using sorbent, coagulant and coarsely dispersed mineral substance. The water withdrawn from the reservoir is subsequently purified by filtration through a hydrocarbon fluid layer, sorption in a carbon-containing fibrous material, filtration in a geochemical barrier filled with mineral granular material, where electrochemical current sources generating the coagulant are disposed. Purified water is returned to the reservoir, where the mixing of purified and untreated water is limited. At the same time, interception of ground water-oil emulsions entering the reservoir and their purification by liquid filtration in hydrocarbon fluid layer with afterpurification together with water extracted from the reservoir are performed. The extracted bottom sediments are composted together with carriers of microorganisms, structurants and biogenic elements.

EFFECT: improved efficiency of water and reservoir bottom sediments purification.

1 dwg, 4 ex, 4 tbl

Description

The invention relates to methods for cleaning non-flowing bodies of water from oil products and heavy metals contaminated with technogenic flows of oil-water emulsions coming from petrochemical and oil refining enterprises operating for many years.

There is a method of cleaning water from oil, including spraying a solution of an oil-oxidizing preparation and mineral fertilizers, aeration to increase the oxygen content in water (RF Patent No. 2322400).

The disadvantage of the proposed method is the inability to purify water from heavy metals.

The closest in technical essence and the achieved result is a method of purifying contaminated water of surface water bodies from oil products and heavy metals by adding a sorbent, flocculant, coagulant and mineral opacifier [RF Patent No. 2143403]. A mixture of hydrolyzed dispersed aluminosilicates is used as a sorbent and a mineral opacifier, aluminosilicates in a colloidal state are used as a flocculant, and a composition of hydroxides of various metals (aluminum, iron, titanium, calcium and magnesium) is used as a coagulant.

The essence of the method lies in the fact that the introduced reagents sorb petroleum products and heavy metals in the pond, and precipitate them. However, petroleum products and heavy metals extracted from water pass into bottom sediments and are deposited there. Moreover, all of these metals in the form of hydroxides will also be deposited in bottom sediments, worsening the ecological situation of the reservoir.

The disadvantage of this method is the low cleaning effect of the water body, including water and bottom sediments.

The objective of the invention is to increase the efficiency of water purification and bottom sediments of a reservoir.

The technical result coincides with the objective of the invention.

The essence of the method for cleaning non-flowing water bodies is to use a sorbent, coagulant and coarse mineral substance. According to the invention, the water extracted from the reservoir is purified sequentially by filtration through a layer of hydrocarbon liquid, sorption in a carbon-containing fibrous material, filtration in a geochemical barrier filled with mineral granular material, which contains electrochemical current sources generating a coagulant, and purified water is returned to the reservoir in which it is limited mixing purified and untreated water, while intercepting the water-oil emulsions entering the reservoir and their eyes sewage by liquid filtration in a layer of hydrocarbon liquid with tertiary treatment together with water extracted from a reservoir, and the extracted bottom sediments are composted together with microorganism carriers, structure-forming agents, biogenic elements.

The figure shows a flow diagram of a process for treating water in a non-flowing body of water.

Slit intake pipes 2 are placed in the reservoir 1, connected to a pumping station 3, having a discharge into a liquid hydrophobic filter 4, connected in series with a sorption filter 5 and a geochemical barrier 6. Electronegative rod electrodes made of aluminum 7 and electropositive rod electrodes made of aluminum are placed in the geochemical barrier 6 copper 8. The electrodes form alternating rows perpendicular to the flow of water. The hydrophobic filter 4 is connected to the drive 9 of petroleum products.

The exit of the geochemical barrier 6 is connected to the slotted water distribution pipe 10. In the pond between the pipes 2 and 10 there is a floating semi-submersible partition 11.

In the coastal zone of the reservoir there is a compost site 12 connected by a pipeline to the pumping station 13 for pumping bottom sediment, located on watercraft in the reservoir 1. Compost site 12, equipped with a waterproofing screen and an aeration system (not shown in the figure). A drainage pump 14 connected to a slotted water distribution pipe 15 is connected to the drainage system of the compost site 12.

The storage bins 16 of the components of the compost mixture are connected to a mixer 17 having an outlet to the compost pad 12.

The geochemical barrier 6 is equipped with a backwash system consisting of a slotted water intake pipe 18, a pump station 19, a dispersed outlet 20 of the geochemical barrier 6, and a discharge pipe for washing water 21 to the compost site 12.

On the high bank of the reservoir, from the side of technogenic oil-containing water flows, there is a collector 22 for intercepting oil-containing water in the form of a trench, at the bottom of which there is a slotted pipe 23 connected to a pumping station 24 for transferring the captured oil-water emulsion to a hydrophobic filter 25 connected by pipelines to the oil storage 9 sorption filter 5.

The method is as follows.

In recent years, numerous facts of pollution of soils and water bodies by oil products by petrochemical and oil refining enterprises during the long-term activity of these enterprises in the normal mode have been established. The facts of soil impregnation with petroleum hydrocarbons to a depth of 30 m have been established. Technogenic flows of oil-water emulsions formed in the soils directed along the slope of the area towards water bodies, as a result of which high concentrations of hydrocarbons were found both in water of water bodies and in bottom sediments.

Reanimation of stagnant water bodies in such cases is very difficult to implement, because there is a constant feed of reservoirs with new doses of hydrocarbons.

First of all, it is necessary to prevent the flow of hydrocarbons from industrial enterprises located in high places. For this, water-oil emulsions are intercepted using a collector 22, buried to the entire depth of the soil impregnation. The captured emulsion is pumped out using a slit pipe 23 and a pump station 24 onto a hydrophobic filter 25 to separate oil and water by liquid filtration through a layer of hydrocarbon liquid. Separated oil products are taken to accumulator 9, and water is sent for purification from the remaining oil products and from heavy metals that pass from oil products to water to a sorption filter 5.

The most polluted water from the reservoir 1 using the intake pipe 2 and pump station 3 is fed into a liquid hydrophobic filter 4.

One of the options for an efficiently working hydrophobic filter is known from the patent of the Russian Federation for PM No. 139209. In the process of filtering oil-containing water in a liquid hydrophobic filter, 2 streams are formed: a stream of purified water from oil products sent for further purification, and a stream of dehydrated hydrocarbons sent to the accumulator 9 of oil products.

The water flow then enters the sorption filter 5, filled with cassettes with a natural sorbent, which is used as a carbon-containing fibrous material - cereal straw - having a high sorption capacity of about 4 g of oil per 1 g of sorbent.

Water purification from fine suspended solids and hydrocarbons remaining in water after preliminary purification by liquid filtration and sorption, as well as from heavy metals occurs in the geochemical barrier 6. The geochemical barrier is an extended filter up to 16 m long, filled with active filtering material - silicified calcite ( RF patent No. 2086510). Electrochemical current sources formed by galvanic aluminum-copper pairs are arranged in rows in the body of the filter material. When the filter is filled with water, electrochemical current sources create an electromotive force, under the action of which aluminum electrodes dissolve with the formation of hydroxide Al (OH) ₃ . Aluminum hydroxide is an effective coagulant widely used in the practice of purifying water from heavy metals. Silicate calcite, which has alkaline properties, accelerates the process of flocculation.

The purified water is discharged by gravity into the reservoir using a water distribution pipe 10. A floating semi-submersible baffle 11 makes it difficult to exchange water in the reservoir, separating the clean and dirty water zone.

The hydrophobic filter 4 does not require regeneration. The sorption filter 5 when its capacity is exhausted is restored by replacing the cartridges with sorption material. The geochemical barrier 6 has a high load capacity due to the large porosity (fraction of silicified calcite 2-5 mm) and a length of up to 16 m, but, nevertheless, it is necessary to regenerate it, given the duration of the restoration of water quality in the reservoir.

The backwash of the filter is carried out with water taken from the reservoir 1 by a slotted water intake pipe 18 and a pumping station 19 supplying water to the dispersed outlet 20 of the geochemical barrier 6. The washing water containing the extracted heavy metals and oil products is fed to the compost pad 12.

On the compost site 12, in addition, serves bottom sediments pumped out by the pumping station 13, as well as carriers of microorganisms, structure formers, nutrients using storage bins 16 and mixers 17.

The optimal composition of the mixture%:

- Precipitation of biological treatment facilities of oil refineries (refineries) - 1;

- bird droppings - 1;

- straw, sawdust, peat, paper - 8;

- Precipitation of biological sewage treatment plants of settlements - 20;

- Precipitation of treatment facilities for water supply of settlements - 10;

- mineral granular material - silicified calcite - 10;

- catalyst for oxidation processes - 5;

- bottom sediments of the reservoir - the rest.

The duration of composting depends on the concentration of pollutants and ranges from 3 to 12 months. The resulting compost is used for reclamation of the coastal zone of the reservoir.

Example 1

Experiments were carried out on the purification of a model of natural water containing iron ions with a geochemical barrier 16 m long with a filtration rate in the range of 0.1-1 Ohm / h. The results are shown in table 1.

From the table it follows that to obtain water with an iron concentration of 0.3 mg / l (MPC _{household water} - the maximum allowable concentration of water bodies for drinking), the necessary effect of water treatment is 90%, i.e. a filtration rate of 5.0 m / h is possible with a geochemical barrier length of 12 m.

Example 2

Experiments were carried out on the purification of a model of natural water containing manganese ions with a geochemical barrier 16 m long with a filtration rate in the range of 0.1-10 m / h. The results are shown in table 2.

From the table it follows that to obtain water with a concentration of manganese OD mg / l (MPC _household water), the necessary effect of water purification is 90.0%, that is, a filtration rate of 5.0 m / h is possible with a geochemical barrier length of 12 m.

Example 3

Experiments were conducted on the purification of a model of natural water containing copper ions with a geochemical barrier 16 m long with a filtration rate in the range of 0.1-10 m / h.

The results are shown in table 3.

From the table it follows that to obtain water with a copper concentration of 1.0 mg / l (MPC _{household.pit} ), the required effect of water purification is 99.00%, i.e. a filtration rate of 5.0 m / h is possible with a geochemical barrier length of 8 m.

Example 4

Experiments were conducted on the purification of a model of natural water containing benzene with a geochemical barrier 16 m long at a filtration rate in the range of 0.1-10 m / h. The results are shown in table 4.

From the table it follows that to obtain water with a benzene concentration of 0.1 mg / l (MPC _household water), the necessary effect of water purification is 90.00%, that is, a filtration rate of 5.0 m / h is possible with a geochemical barrier length of 16 m

The technical result consists in the fact that the cleaning of the bottom sediment to the quality of soil and water treatment of the reservoir to the maximum allowable concentrations of heavy metals and petroleum products.

Claims (1)

The method of cleaning non-flowing reservoirs under conditions of continuous oil products from heavy metals and oil products by using a sorbent, coagulant and coarse mineral substance, characterized in that the water extracted from the reservoir is purified sequentially by filtration through a layer of hydrocarbon liquid, sorption in a carbon-containing fibrous material, filtration in a geochemical barrier filled with mineral granular material, which contains electrochemical current sources, generating coagulant, and the purified water is returned to the reservoir, in which the mixing of the purified and untreated water is limited, while the groundwater-oil emulsions entering the reservoir are intercepted and purified by liquid filtration in a layer of hydrocarbon liquid with additional treatment together with the water extracted from the reservoir, and the bottom sediments are composted together with carriers of microorganisms, structure-forming agents and biogenic elements.

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