RU2351410C2 - Composition for purification of oil slime and soil from oil pollutants - Google Patents

Abstract

FIELD: sewage treatment facilities.

SUBSTANCE: invention is related to the field of environment protection and may be used for purification of oil slime and soil from oil pollutants. Composition for purification of oil slime and soil from oil pollutants contains oil-oxidising microorganisms - active sludge - from sewage treatment facilities of oil refinery, selected from distributing chamber of secondary settling tanks after 0-8 hours after changeover to regeneration, fertiliser and adsorbent. Fertiliser used is dry excess activated sludge from sludge plates, and adsorbent is chips of leaf-bearing trees, at the following ratio of components, wt %: activated sludge - 8-10, dry excess sludge - 8-10 and adsorbent - 80-82.

EFFECT: development of efficient composition for local treatment from oil pollutants.

3 dwg, 3 tbl, 4 ex

Description

The invention relates to the field of environmental protection from oil pollution and can be used for local cleaning of oil sludge and soil from oil and oil products.

A known composition for cleaning from oil pollution of the soil using oil-oxidizing microorganisms, complex fertilizers, adsorbent (wood waste) [1].

The disadvantage of this invention is the high cost of biological products and their low efficiency.

The closest analogue is the composition according to the method of processing oil-contaminated soil [2], containing, wt.%: Activated sludge 1-2, manure 25-35, adsorbent 63-74. Once a month, the contaminated soil is loosened to a depth of 50-55 cm.The optimal amount of adsorbent and activated sludge in the soil cleaning composition is determined according to the obtained formulas for the dependence of the degree of biodegradation of oil products on the adsorbent content in contaminated soil and the dose of activated sludge, taken as a prototype.

This composition has the following disadvantages:

- the use of sludge for the restoration of farmland can lead to the accumulation of toxic substances in the soil (heavy metals, arsenic compounds, cadmium, pesticides), the development of pathogenic microorganisms (E. coli, streptococci, staphylococci, intestinal amoeba, enterococci, Trichomonas, cholera vibrio and. as well as helminth eggs [3] falling into the soil with silt;

- the use of manure as an organomineral additive implies additional costs for its acquisition and transportation;

- low efficiency of the use of the composition, which allows you to clean oil-contaminated soil with oil content up to 0.76%.

The objective of the invention is to develop a more effective local composition for cleaning oil sludge and oil-contaminated soils.

This problem is solved by the fact that in the composition for cleaning oil sludge and soil from oil pollution by introducing activated sludge into the oil-contaminated soil from the sewage treatment facilities of an oil refinery, selected from the distribution chamber of the secondary settlers 0-8 hours after the recovery, fertilizer and adsorbent, according to the invention, dry excess activated sludge is added as fertilizer from sludge cards, and sawdust of hardwood trees is used as adsorbent in the following composition ratio nents, wt.%:

Active sludge 8-10 Dry excess activated sludge 8-10 Adsorbent 80-82

moreover, the microbial mass of sludge (activated sludge from sewage treatment plants with an oil-oxidizing microorganism content of at least 10 ⁵ -10 ⁶ cells / ml and dry excess sludge) and adsorbent are introduced into the oil mix in the mixture. The prepared oil soil is layered in layers with sand and soil, perforated pipes providing aeration are placed between the layers, and sawdust of deciduous trees is introduced as an adsorbent.

To prepare the composition, dry sludge of 8-10 wt.%, Liquid sludge of 8-10 wt.% And sawdust of hardwood trees 80-82 wt.% Are added directly to the oil-contaminated medium with oil and oil products up to 10 wt.%. Dry sludge is a substance with a moisture content of 50-60%, the majority of the dry sludge is made up of substances of protein origin (up to 50%), fats (up to 20%) and carbohydrates (up to 8%). The dry sludge substance contains almost all macroelements necessary for the development of oil-oxidizing microorganisms, wt.%: Humus - up to 60; potassium 0.2-0.7; calcium - 3-5; phosphorus compounds 1-4; nitrogen compounds - 1-3; sulfur compounds - 1-2, etc. [3].

Pre-prepared oil-contaminated soil, soil and sand are laid in a tank. To supply air under the layers of oil-contaminated soil, perforated pipes with a diameter of 5 cm are placed. Perforated pipes are placed at a distance of not more than 50 cm from each other and have a vertical exit to the surface (Fig. 1). Drainage in the form of a layer of sand 10 cm provides a drain of water in the event that excess water enters the tank. The excess water is discharged through the pipe into the receiving tank, from where it is taken and sprayed again on the surface of the site. Throughout the entire cleaning period, the following techniques are carried out:

- a coating in the form of a polyethylene film is provided on top of the tank, which prevents the evaporation of moisture and hydrocarbons, as well as uncontrolled water entering the system in the form of precipitation,

- air supply to the perforated pipe system in an amount of 0.5 m ³ / h,

- watering as necessary with water up to 60% of the moisture capacity,

- the temperature for the cleaning period should not be lower than 10 ° C.

Example 1. For the experiment, soil samples were prepared with different contents of oil products (0.5%, 1%, 2%, 3%, 5%, 10%). As oil-oxidizing agents, we used the dried biomass of excess activated sludge from sludge cards in an amount of 10 wt.% And a suspension of activated sludge taken from the distribution chamber of secondary sumps in an amount of 10 wt.%. In a series of experiments A, liquid activated sludge and dry activated sludge were introduced separately with an adsorbent, and in a series of experiments B, they were added together. The adsorbent was taken in an amount of 80 wt.%. For each soil sample, separate earthen tanks with concreted walls (height 80 cm, length and width 50 cm) were prepared, placed on an open landfill. Sand, soil and oil-contaminated soil were stacked in layers in the tank, perforated pipes having a common exit to the surface were installed between the layers (Fig. 1). As necessary, water was irrigated to a moisture content of the upper layer of 60%. The effectiveness of the biodegradation of oil and oil products was judged by the change in their concentration in soil samples. The content of oil and oil products in the soil was determined by weight and spectrophotometric methods according to the known method after extraction with carbon tetrachloride [4]. The concentration was determined after 30, 60 and 90 days. For the experiment, samples were taken from various loading layers, which were then averaged. The control was a tank in which oil-contaminated soil was not treated with microbial mass, layer-by-layer arrangement of oil-contaminated soil with activated sludge and sand was not carried out, and aeration was not carried out.

In the course of the work, it was found that the degree of biodegradation in 90 days when the content of oil and oil products is 0.5%, 1%, 3%, 10% for the combined application of the microbial mass of sludge and adsorbent is 72.3%, 59.6 %, 44.7%, 28.1%, for separate application of the microbial mass of sludge and adsorbent - 61.7%; 50.8%; 39.8%; 22.5% respectively, i.e. after preliminary mixing, the effect of bio-purification is 7-10% higher (Table 1).

Example 2. The experiment was conducted according to the scheme of example 1 using a mixture of dry dry sludge from sludge cards and liquid activated sludge with an adsorbent. In this example, the dried biomass of excess activated sludge and a suspension of activated sludge were introduced into the oil-contaminated soil together in a different ratio. In the course of the work, it was found that when the dried biomass of excess sludge and a suspension of activated sludge were added together in oil-contaminated soil, the greatest effect of biodegradation of oil products was observed when the ratio of dry activated sludge to liquid biomass was 8:10 (Table 2).

Example 3. The experiment was conducted according to the scheme of example 2 by the joint application of dry excess sludge from sludge cards of 8 wt.% And liquid activated sludge of 8 wt.% Into oil-contaminated soil. In this example, in order to improve the agrochemical properties, sawdust of deciduous trees was introduced into the oil-contaminated soil together with the microbial mass of silt at the rate of 10, 30, 40, 50, 80 and 82 wt.% (The rest is sand).

Thus, the content of sawdust (adsorbent) in an amount of 80-82 wt.% In a mixture with the microbial mass of sludge enhances the effect of cleaning oil-contaminated soils by 8-10% (Table 3).

Example 4. The experiment was carried out according to the scheme of example 3 with an additional three-time top dressing with a composition containing dried biomass of excess sludge from sludge cards of 8 wt.% And activated sludge from the distribution chamber of the secondary settling tanks of 10 wt.%. The degree of biodegradation was determined by the residual amount of petroleum products by a known method [4]. The residual content of oil and oil products is presented in figure 2. The results of determining the degree of biodegradation of oil and oil products are shown in figure 3.

As can be seen from figure 3 with three meals a day for 240 days, a 99% cleaning effect is achieved.

List of sources used

1. RF patent No. 2112610, Garayev I.Kh., Gareishina A.Z., Akhmetshina S.M. Composition for cleaning the soil from oil pollution and a method of cleaning the soil from oil pollution. // Inventions. - 1998.

2. RF patent No. 2175580, Chertes KL, Bykov D.E., Shinkevich M.Yu. and other Composition for cleaning the soil from oil pollution and a method of cleaning the soil from oil pollution. // Inventions. - 2001.

3. Trubnikova L.I. Disposal of excess activated sludge from petrochemical enterprises. // Ecology and industry of Russia. 2001. No. 8, from 9-11.

4. Lurie Y. Yu. Unified methods of water analysis. - M.: Chemistry, 1973.

- 215 p.

Claims (1)

Composition for cleaning oil sludge and soil from oil pollution, containing activated sludge as oil-oxidizing microorganisms from the sewage treatment facilities of an oil refinery, taken from the distribution chamber of the secondary settling tanks 0-8 hours after removal to regeneration, fertilizer and adsorbent, characterized in that as fertilizers use dry excess activated sludge from sludge maps, and sawdust of deciduous trees, with the following ratio of components, wt.%: as adsorbent
Active sludge 8-10 Dry excess sludge 8-10 Adsorbent 80-82

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