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Table 3 Key techniques for soil remediation

From: Key technologies and equipment for contaminated surface/groundwater environment in the rural river network area of China: integrated remediation

Remediation technique

Technique principle

Characteristics

Physical–chemical remediation

 Vapor extraction

Drive air through the pores of the contaminated soil, thereby entraining VOCs to the extraction system, pumping to the ground, and then collecting and processing

Suitable for unsaturated areas, sites with strong permeability, and volatile organic pollutants

 Thermal desorption

The organic pollutants in the soil will accelerate decomposition and volatilization during the heating process, and the contaminated gas is extracted and collected from the soil through the suction system to process

Suitable for volatile organic matter and semi-volatile organic matter

 Immobilization/stabilization

Immobilization: encapsulating soil pollutants in a solid material with complete structure; Stabilization: transfer pollutants into a state or form that is not soluble, transportable, or less toxic, reducing the bioavailability of pollutants

Contaminants cannot be fundamentally removed

 Chemical redox

Add oxidant or reducing agent to contaminated soil, through oxidation or reduction, so that the pollutants in the soil into non-toxic or relatively less toxic substances

Not suitable for remediation of heavy metal contaminated soil

 Soil washing

The eluent is injected into the contaminated soil, with the help of chemical/biochemical solvents that can promote the dissolution or migration of pollutants, transfer pollutants from the soil phase to the liquid phase. The wastewater from the elution system should be further treated

Not suitable for soil with a fine (clay/powder) content of more than 25%

Ecological remediation

 Phytoremediation

Use plants for extraction, rhizosphere filtration, volatilization, and fixation to remove, transform, and destroy pollutants in the soil, so that the polluted soil can restore its normal functions

Long processing time and slow results

 Microorganism remediation

The method of transforming, degrading, and removing pollutants in the environment by using indigenous microorganisms in the natural environment or artificially adding exogenous microorganisms

Suitable for integrated use with other methods