RU2231944C2 - Method for biological cleaning of soil - Google Patents

Abstract

FIELD: methods for biological cleaning of soil contaminated with heavy metals.

SUBSTANCE: method involves sowing plant seeds into contaminated soil; mowing and removing green mass, with cankerwort seeds being used in an amount of 1.95-24.3 million pieces per 1 hectare; upon seed germination, growing plants to crown phase; providing repeated mowing and removal of green mass until seeds are formed.

EFFECT: increased efficiency in reducing of heavy metal content in soil.

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Description

The invention relates to the field of biological treatment of soils contaminated with heavy metals.

A known method of biological treatment of soils, including sowing plant seeds, mowing and removing green mass (patent US 5720130, IPC A 01 B 79/02, 02.24.1998).

The disadvantage of this method is the low efficiency of soil cleaning from heavy metals.

The technical result is to reduce the content of heavy metals in soils contaminated with these elements.

The essence is that in the method of biological treatment of soils contaminated with heavy metals, including sowing plant seeds in contaminated soil, mowing and removing green mass, sown seeds of dandelion in the amount of 1.95-24.3 million units per 1 ha, after seed germination, the plants are brought to the stage of formation of a rosette of leaves, and mowing and removal of green mass is carried out repeatedly until seed formation.

The method is as follows. In areas that need to be effectively cleaned of heavy metals, the seeds of medicinal dandelion are sown (Taraxacum officinale Wigg. S.1.), The plants are brought to the stage of formation of a rosette of leaves, and when a large mass is formed, mowing and collection of green mass are carried out to form flowering shoots. This procedure is repeated periodically as the aerial part of the dandelion grows in order to prevent the formation of seeds that will inhabit neighboring territories. The number of seeds proposed for application (from 1.95 to 24.3 million units per 1 ha) ensures the optimal density of the population and the resulting raw biomass of the aerial part. It should be borne in mind that in compacted crops, germination progressively decreases from 90 to 70%. The removal of heavy metals (considered using zinc as an example) from soil through phytoextraction also depended on the density of sowing (Table 1).

Thus, after the plants are completely harvested, the effect of the removal of heavy metals from the contaminated area with optimal seed application is maximum. In this case, zinc pollution of the soil was as close as possible to the maximum permissible concentration (at the lower seeding rate) or became lower (at the upper seeding rate). Medicinal dandelion is able to accumulate large amounts of Pb, Cu, Zn, Ni, Fe, Mn and Cr in the aerial part. The determinations carried out on soils of various types and degrees of pollution showed that dandelion especially well accumulates manganese in chernozems and floodplain soils in mid-summer, and iron on superaquinal landscapes at a pH of about 7. The best effect on the removal of iron from soils gives mowing dandelion in mid-summer and early autumn. Biological detoxification of soils contaminated with lead is best done by dandelion in the fall, on aquatic landscapes, at pH greater than 6.

Taking into account that the average water content in dandelion leaves is 78% and the green mass yield varies from 700 to 1000 kg / ha, it is possible to calculate the possible removal of heavy metals from 1 km ^{2 of} soil when growing this species under various conditions (Table 2 )

The sloped green mass is dried and subjected to ashing, as Briquetting and disposing of ash is much more convenient (due to the significantly smaller mass volume). It is advisable to carry out a full harvest of plants at the end of the growing season in the second or third year after sowing.

Compared with known solutions, the proposed method can significantly reduce the content of heavy metals in contaminated soils.

Claims (1)

The method of biological treatment of soils contaminated with heavy metals, including sowing plant seeds in contaminated soil, mowing and removing green mass, characterized in that the seeds of dandelion are sown in the amount of 1.95-24.3 million units per 1 ha, after seed germination the plants are brought to the stage of formation of the rosette of leaves, and the mowing and removal of green mass is performed repeatedly until the formation of seeds.