RU2446899C1 - Method of combined reagent detoxification and remediation of soils - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: invention relates to the field of environment and can be used for reagent detoxification and remediation of soils contaminated with arsenic compounds in the areas where previously chemical weapons were destructed. The method includes consistent application of a layer by layer meliorative coating and 20-cm soil layer. Subsequent pooling of the surface by seeding rhizomatous perennial grasses of rump and wheatgrass in a weight ratio of seeds of 1:1 and a seed rate 20 kg/ha. The area is pretreated with equivalent amounts of thiourea dioxide (TUD), but not more than 0.5 tons, a modified amino acid composition, but not more than 0.5 tons per 100 m² of cultivated land with a total arsenic content of not more than 3000 mg/kg and heavy metals no more than 7000 mg/kg, until the pH of the aqueous extract from the soil reaches at least 8 and the value of amino acid ratio is not less than 2, then a layer of glauconite of not more than 5 cm, followed by coating of 5-cm layer of zeolite-containing soil, a layer of calcareous clay with capacity of 10 cm, the soil mixture with a polymer of water-absorbing acrylamide AK-639 of type B-415K in a volume ratio of 150:1 in a layer of 10 cm.

EFFECT: invention reduces the amount of toxic water-soluble forms of arsenic and heavy metals in highly polluted soil of tested site by 4-6 times, thus carrying out a stable detoxification and remediation of soils.

Description

The invention relates to the field of environmental protection and can be used for reagent detoxification and remediation of soils contaminated with arsenic compounds in places of the previous destruction of chemical weapons.

Known methods of chemical, electrochemical and biological treatment of soils and soils from radioactive and toxic substances, based on the use of humic-mineral reagents, direct current and plants that accumulate toxic substances in the vegetative mass [1-3].

Known methods differ in a number of significant drawbacks: high complexity, complexity in execution, as well as a long time to obtain results, and therefore have not received widespread use in environmental practice.

The prototype is a well-known method of reclamation of contaminated land, based on the absorption and retention of moisture with toxic substances dissolved in it, entering the soil during precipitation and snow melting, natural and chemical reclamants [4].

The remediation method of the prototype is as follows.

Reclamation of the site where chemical weapons were destroyed in the past is carried out in the following order. Initially, its surface is covered with a 10-cm layer of zeolite-containing rock, which helps to prevent the diffusion of degradation products of toxic substances from contaminated soil into the layer of upstream reclamants. Then the zeolite-containing rock is covered with a layer of carbonate clay with a thickness of 15 cm, which ensures the interception of water not absorbed by the acrylamide polymer and soil, and also contributes to the deoxidation of soil moisture due to the high content of carbonates. A mixture of soil with a polymer of acrylamide of water-absorbing AK-639 grade B-415K in a volume ratio of 100: 1 is applied to a layer of carbonate clay in a 100: 1 layer with a 10 cm layer. A 20-cm layer of soil is applied on top, used to further mend the surface, including sowing of rhizome perennial grasses / rump and wheat grass / in a weight ratio of seeds 1: 1 and a seeding rate of 20 kg / ha.

The disadvantages of this method are:

- The method is developed for soils contaminated with one component with a limited level of its content (arsenic not more than 50 mg / kg);

- The method is not intended for the restoration of lands contaminated with arsenic compounds with a high content and heavy metals;

- The method is not effective in violation of the reclamation protective layer, for example in the case of weathering or unregulated self-growth of woody vegetation.

The objective of the invention is the sustainable detoxification and remediation of soils with arsenic contents up to 3000 mg / kg and heavy metals up to 7000 mg / kg.

The problem is solved as follows.

In the method of detoxification and soil remediation, including applying a layered ameliorative coating consisting of zeolite-bearing rock, carbonate clay, chernozem soil with acrylamide polymer of water-absorbing AK-639 grade B-415K in a volume ratio of 150: 1 with a layer of 10 cm, carry out preliminary reagent treatment arsenic and heavy metals of the soil area with glauconite, equivalent amounts of thiourea dioxide (DTM) and a modified amino acid composition.

The process is carried out as follows.

Initially, the recultivated area is treated with an equivalent amount of DTM of not more than 0.5 t per 100 m ^{2 of} soil, modified amino acid composition (AK-ZE TU 18517698-3-98) not more than 0.5 t per 100 m ^{2 of} soil with total arsenic content in the soil no more than 3000 mg / kg and heavy metals no more than 7000 mg / kg for binding arsenic and heavy metals to stable low toxicity complexes of hazard class 4, then with a glauconite layer of 5 cm.The treatment is considered satisfactory at a pH of an aqueous extract from the soil of at least 8 and a value amino acid coefficient not her 2.

A day later, the surface of the site is covered with a 5-cm layer of zeolite-containing rock, which helps to prevent diffusion of degradation products of toxic substances from contaminated soil into the layer of upstream reclamants. Then the zeolite-containing rock is covered with a layer of carbonate clay with a thickness of 10 cm, which ensures interception of water not absorbed by the acrylamide polymer and soil, and also contributes to the deoxidation of soil moisture due to the high content of carbonates. A mixture of soil with a polymer of acrylamide AK-639 water-absorbing grade B-415K in a volume ratio of 150: 1 is applied to a layer of carbonate clay in a volume ratio of 150: 1 with a layer of 10 cm. A 20-cm layer of soil is applied on top, used to further mend the surface, including sowing of rhizome perennial grasses / rump and wheat grass / in a weight ratio of seeds 1: 1 and a seeding rate of 20 kg / ha.

The effectiveness of detoxification was evaluated by reducing the amount of arsenic salts in aqueous extracts from the soil by 4-6 times. The effectiveness of the new reclamation method was evaluated by the germination of legumes, which are highly sensitive to chemical pollution of the land. The classical method of counting the number of sprouted seedlings, which was published in the literary source "Methodology of state testing of agricultural crops", was used. - Part 1-2. - M., 1965. The analysis showed that after reclamation the germination of pink clover increased by 27-32%, which indicates the high efficiency of the new method.

The technical result achieved by the implementation of this method of detoxification and reclamation is that the content of toxic water-soluble forms of arsenic and heavy metals decreases in highly contaminated soil of the test site by 4-6 times, which makes it possible to carry out sustainable detoxification and soil restoration.

The proposed solution allows for combined detoxification and reclamation of soils and soil heavily contaminated with arsenic and heavy metals with additional protection when the reclamation layer is disturbed, to reduce the thickness of the reclamation coating, to expand the range of detoxified pollutants, i.e. to carry out detoxification and remediation of soils contaminated with arsenic-containing products of destruction and destruction of OB.

Literature

1. Patent for invention No. 2233293 / Russia /. Gumino-mineral reagent and method for its preparation, method for sanitation of contaminated soils, method for detoxification of waste products from mining and processing of minerals and reclamation of rock dumps and tailings, method for wastewater treatment and a method for utilizing sludge. / A.I. Shulgin, A.A. Shulgin / 11.27.2002.

2. Patent for invention No. 2211493 / Russia /. The method of electrokinetic cleaning of soils from radioactive and toxic substances. / A.S. Barinov, L.B. Prozorov, V.B.Nikolaevsky and others / 08.27.2003.

3. Patent for invention No. 2231944 / Russia /. The method of biological treatment of soils. / A.S. Lukatkin, D.I. Bashmakov / 10.07.2004.

4. Patent for invention No. 2229882 / Russia /. The method of land reclamation. / A.I. Ivanov, P.A. Ivanov, A.P. Statsenko / 06.20.2006.

Claims (1)

The method of combined detoxification and remediation of contaminated lands, including the sequential application of a layered ameliorative coating and a 20-cm soil layer with subsequent tinning of the surface by sowing rhizomatous perennial grasses of rump and wheat grass in a weight ratio of seeds 1: 1 and a sowing rate of 20 kg / ha, characterized in that the site is pre-treated with equivalent amounts of thiourea dioxide (DTM), but not more than 0.5 t, modified amino acid composition, but not more than 0.5 t per 100 m ^{2 of} processing the washed area with a total content of arsenic of not more than 3000 mg / kg and heavy metals of not more than 7000 mg / kg until the pH of the aqueous extract from the soil is not less than 8 and the amino acid coefficient is not less than 2, then glauconite layer is not more than 5 cm, followed by 5 with a centimeter layer of zeolite-containing rock, a 10 cm thick layer of carbonate clay, a mixture of soil with acrylamide polymer of water-absorbing AK-639 grade V-415K in a volume ratio of 150: 1 with a 10 cm layer.