Widely-applicable high-efficiency nondestructive method for repairing heavy metal polluted farmland in situ

Abstract

The invention discloses a widely-applicable high-efficiency nondestructive method for repairing a heavy metal polluted farmland in situ. The method realizes in-situ nondestructive repair, stabilization and fertility increase of heavy metal polluted farmland soil through steps such as plowing, ridging, water irrigation for soaking, adsorption through movable adsorption modules, soaking water internal circulation, soil stabilization and fertility increase performed to the polluted farmland soil. The method does not need additional additives, does not destruct the soil structure and composition, can realize deep high-efficiency purification of heavy metals of various types and forms, has the advantages of wide application scope, small workload, short treatment period, low cost and the like, and is very applicable to the treatment of the heavy metal polluted farmland soil.

Description

technical field [0001] The invention belongs to the technical field of contaminated soil remediation, and in particular relates to a method for widely suitable, efficient and non-destructive in-situ remediation of farmland polluted by heavy metals. Background technique [0002] At present, my country's cultivated land is seriously polluted by heavy metals, and about one-sixth of the cultivated land in the country is polluted by heavy metals to varying degrees. Among them, Cd, Ni, Pb, etc. are the main heavy metals polluting cultivated land. The above-mentioned heavy metals mainly enter the cultivated land through sewage irrigation, industrial waste discharge, excessive use of pesticides and fertilizers, etc., causing soil heavy metal pollution. Heavy metal pollution in arable land will cause crop yield reduction and excessive heavy metals, which will threaten people's health. In recent years, soil heavy metal pollution incidents have occurred frequently in my country, and ...

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Problems solved by technology

Among them, the invention patent (Application No. 201410358118.1) adopts irrigation soaking, soil heavy metal desorbent (organic complexing agent) to analyze soil heavy metals, attapulgite adsorption, and electric separation method to separate attapulgite and other steps to control heavy metals, and the treatment effect copper removal rate is about 82%. , lead about 55%; at the same time, artificial organic complexing agent, attapulgite powder, etc. are added to the soil, among which the organic complexing agent cannot be recovered and remains in the soil, and some attapulgite powder can be recovered by electric separation, but there will still be residual On the one hand, the above-mentioned substances will destroy the composition and properties of the soil; on the other hand, the environmental and ecological risks of the added chemical substances have not been evaluated, and there is a trend of new soil pollution; in addition, this method has a large amount of engineering, and at the same time, the electric separation method is used to recover the attapulgite Not only the cost of use is high, but also there are security risks

Invention patents (application numbers 201410285259.5, 201510186798.8) use steps such as sampling, analysis, weeding and soaking, activation, displacement adsorption, stirring and magnetic absorption, and centralized collection to control heavy metals in farmland; , and will not be recycled, and all remain in the soil. On the one hand, the addition of the above substances will destroy the soil composition and structure, and change the soil micro-ecological system. On the other hand, the environmental and ecological risks of the added chemical substances have not been evaluated, and there will be new soil pollution It is debatable whether the original function of the soil can be restored; in addition, this method requires a large amount of engineering

Invention patent (application number 201410240226.9) uses modified straw rope to adsorb and remove heavy metals from soil; however, this method can only adsorb and remove part of water-soluble and ion-exchanged heavy metals, and it is effective for the carbonate-bound state and iron-manganese oxidation that account for most of the soil. The heavy metals in the organic state and organically bound state have almost no removal effect, and the heavy metals in the latter forms will precipitate and re-contaminate the soil when the pH and redox potential of the soil change.

However, limited by the physical and mechanical properties of modified straw ropes, this technology can only be used in soils with a pH of 6-7, while straw ropes are easy to corrode and decompose in acidic or alkaline soils, and cannot play a governance role.

At the same time, the above four invention patents can only adsorb and remove soluble and ion-exchange heavy metals in the soil, but have almost no removal effect on carbonate-bound and iron-manganese oxidation state heavy metals, and cannot achieve efficient and deep purification of heavy metals in soil

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