KR20120087707A

KR20120087707A - Remediation method for heavy metal contaminated soil

Info

Publication number: KR20120087707A
Application number: KR1020110009071A
Authority: KR
Inventors: 유경근; 조봉규
Original assignee: 한국해양대학교 산학협력단
Priority date: 2011-01-28
Filing date: 2011-01-28
Publication date: 2012-08-07

Abstract

The present invention relates to a method for restoring heavy metal contaminated soil.
In the heavy metal contaminated soil restoration method according to the present invention, the step of collecting the soil contaminated with heavy metal and injecting it into the tank containing water, supplying a surface modifier in the tank so that the soil can be reformed into a hydrophilic (親氣性) It is characterized in that it comprises a step of supplying bubbles in the tank and the step of removing the heavy metal suspended above the tank.

Description

Remediation method for heavy metal contaminated soil}

The present invention relates to a method for restoring contaminated soil, and more particularly, to a method for restoring heavy metal contaminated soil for restoring the soil by removing heavy metal from soil contaminated with heavy metals such as arsenic, cadmium, and lead.

Soil pollution occurs through a variety of routes, including waste dumping, hazardous material leaks, pesticide and fertilizer use, and incineration. Soil pollution not only causes various problems such as disruption of soil ecosystem, pollution of crops and human absorption of pollutants, but also acts as a source of pollution that causes secondary pollution of surface water, groundwater and air. In particular, soil pollution is more problematic since it is more chronic than air and water pollution and takes a long time and cost to restore.

Korea recognizes the impact of soil pollution on humans and ecosystems, and has enacted and implemented the Soil Environment Conservation Act. The Soil Conservation appointed pollution reference value for 16 items (Cd, Cu, As, Hg , Pb, Cr 6 +, Zn, Ni, F, of the compound, CN, BTEX, TPH, TCE , PCE organic) administration Doing.

Of these soil pollutants, especially heavy metals can cause fatal diseases such as minamata, itai itai, cancer, etc., the damage caused by heavy metals should be reduced by restoring contaminated soil.

Accordingly, restoration projects for heavy metal contaminated soils have been actively carried out recently. Soil cleaning, electrokinetic extraction, stabilization, phytoremediation, and landfill blocking are commonly applied to clean heavy metal contaminated soil.

Galvanic extraction of the above methods is a method of extracting contaminants from the heavy metal contained in the soil using a direct current. Galvanic extraction method extracts mainly from water-soluble heavy metals from contaminated soil and shows high extraction efficiency only by maintaining water content above a certain level. Some sites use the weak acidic heavy metal leaching solution to apply the process, but it is only applicable to very limited sites due to the limitation of heavy metal leaching.

In addition, in Korea, a lot of stabilization methods are applied to reduce the toxicity, solubility, and mobility of heavy metals by adding adsorbents and precipitants to the soil contaminated with heavy metals, and lime and steel slag are widely used as stabilizers. Lime and steel slag injected into the soil can raise the soil pH to convert highly soluble heavy metals into hydroxide or carbonate forms, but stabilization methods also require long-term restoration of soil due to acid rains and short useful life of neutralizers. There is a problem that the effect cannot be guaranteed.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for restoring heavy metal contaminated soil with improved structure to effectively separate and extract heavy metal from soil contaminated with heavy metal.

Heavy metal contaminated soil restoration method according to the present invention for achieving the above object, the step of collecting the soil contaminated with heavy metal into the tank containing water; Supplying a surface modifier in the water tank so that the soil can be modified to be hydrophilic; Supplying bubbles into the tank; And removing the heavy metal suspended above the water tank.

According to the present invention, the surface modifier is a copper compound or a sulfide compound, copper sulfate is used as the copper compound, and sodium sulfide is used as the sulfide compound.

In addition, it is preferable to supply a foaming agent so that bubbles are sufficiently generated in the water tank.

The present invention has the advantage that the heavy metal and the soil can be very simple and economically separated from the heavy metal contaminated soil by using different properties of the soil and heavy metals, that is, hydrophilicity and hydrophilicity.

1 is a schematic flowchart of a heavy metal contaminated soil restoration method according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings, a heavy metal contaminated soil restoration method according to an embodiment of the present invention will be described in detail.

Referring to Figure 1, in the heavy metal contaminated soil restoration method according to an embodiment of the present invention first begins with the step of collecting soil contaminated with heavy metals.

In the collecting stage, the heavy metal contaminated soil to be treated is excavated and collected. This heavy metal contaminated soil varies in the main pollutants depending on the collection sites such as plating factories and mining related factories, and contains a large amount of heavy metals such as arsenic, zinc, lead, cadmium and chromium.

After collecting the contaminated soil, crushing of the contaminated soil may be performed before proceeding to the next step. You can also distinguish between coarse and fine particles through the sieve.

As described above, when the collection and grinding of the soil is completed, the contaminated soil is introduced into the tank. The tank contains water, which causes the contaminated soil to separate into heavy metals and soil.

That is, polluted soils are largely divided into soil and heavy metals. In general, heavy metals are not intimate with water but have an affinity for air, while soil components are mainly hydrophilic with water. When bubbles are supplied to the tank, the heavy metal component is bound to the bubbles. Heavy metals combined with air bubbles become lighter than water, so they float from the top of the tank while being separated from the remaining soil components.

The present invention focuses on the hydrophilicity of the soil particles and the hydrophilicity of the heavy metal particles, so that the soil particles and the heavy metal particles can be separated from each other in the tank, and air bubbles are supplied to the tank so that the separation action can occur smoothly. It is.

In addition, depending on the type and conditions of heavy metals, the heavy metal particles may not have sufficient affinity. In this case, since the separation from the soil is not easy, in the present invention, the surface of the heavy metal is modified to increase the bonding force with air. That is, the surface modifier is added to the water tank, and the surface modifier is bound to the heavy metal particles. Surface modifiers have a very strong hydrophilicity and have a very good reaction with heavy metals.

In addition to injecting the bubble into the tank or in advance the surface modifier is injected into the tank to be combined with the heavy metal particles. When air bubbles are supplied to the water tank while the heavy metal particles are bound to the surface modifier, the surface modifier is strongly attached to the air bubbles and floats to the top of the water tank. At this time, the heavy metal also floats to the top of the tank together.

As the surface modifier, a copper-based compound or a sulfide-based compound is used. In this embodiment, copper sulfate (Cu (SO ₄ ) ₂ ) is used as the copper-based compound, and sodium sulfide (Na ₂ S) as the sulfide-based compound. ) Is used.

In addition, in the present invention, a foaming agent is added to the tank so that bubbles are sufficiently generated in the tank. MIBC (isobutylcarbinol, 4-methyl-2-pentanol) is used as the foaming agent in this embodiment.

As described above, after the contaminated soil is introduced into the water tank, a surface modifier for modifying the surface of the contaminated soil is added, and when air bubbles and foaming agents are supplied together, the air bubbles directly bind heavy metal particles or mediate the surface modifier. As a result, heavy metal particles separate from the soil and float to the top of the tank.

After waiting for the above-mentioned action to occur sufficiently in the tank, the heavy metal particles suspended in the upper portion of the tank can be separated and recovered very easily from the contaminated soil.

Applicant tried the effect of the heavy metal contaminated soil restoration method according to the present invention.

The process as described above was carried out on contaminated sedimentary soils due to loss during heavy metal component raw material transfer operation in region A.

The soil was contaminated with zinc and the zinc concentration was 7,920 mg / kg. As a result of performing the method according to the present method on 400 g of the contaminated soil, a total of 73 g of the suspended solids floated in the tank, and the concentration of zinc in the suspended solids was very high, 39,580 mg / kg. On the other hand, the sinked soil was 320g and the concentration of zinc in the soil was very low, 615 mg / kg.

In terms of mass, 3168 mg of zinc was present in 400 g of contaminated soil, and the zinc recovered according to the present method showed a high recovery rate of approximately 91.2% at 2889.34 mg, confirming the effectiveness of the present invention.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, it is merely an example, and those skilled in the art may realize various modifications and equivalent other embodiments therefrom. I can understand. Accordingly, the true scope of protection of the present invention should be determined only by the appended claims.

Claims

Collecting the soil contaminated with heavy metals and putting it in a water tank;
Supplying a surface modifier in the water tank so that the soil can be modified to be hydrophilic;
Supplying bubbles into the tank; And
Removing heavy metal suspended above the tank; heavy metal contaminated soil restoration method comprising the.

The method of claim 1,
The surface modifier is a heavy metal contaminated soil restoration method, characterized in that the copper compound or sulfide-based compound.

The method of claim 2,
The copper-based compound is copper sulfate, sulfide-based compound is heavy sulfide soil restoration method characterized in that the sodium sulfide.

The method of claim 1,
Heavy metal contaminated soil restoration method characterized in that the foaming agent is supplied to the tank together with the foam.