Secondary pollution prevention and soil reconstruction using ex-situ washing remediation technology for heavy metal contaminated soil
Ex-situ washing technology for contaminated soil is a remediation method that excavates contaminated soil from its original location, cleans it with a suitable washing agent, and then backfills or transports the clean soil to other locations. This technology is suitable for remediation of soil conta
Ex-situ washing technology for contaminated soil is a remediation method that excavates contaminated soil from its original location, cleans it with a suitable washing agent, and then backfills or transports the clean soil to other locations. This technology is suitable for remediation of soil contaminated by one or more heavy metals such as arsenic, lead, cadmium, chromium, mercury, nickel, copper, etc. The selection of eluent should be optimized based on the type, concentration, distribution, soil properties and other factors of pollutants. The eluent can be different types of chemical substances such as acidic, alkaline, complexing, oxidizing, reducing, etc., or it can be biological agents or plant extracts. The function of the eluent is to desorb or dissolve contaminants from the surface or inside of soil particles so that they enter the eluent.
The process of ex-situ washing technology for contaminated soil generally includes the following steps:
Excavating soil: Excavating contaminated soil from its original location and transporting it to the washing site or washing equipment.
Soil particle screening: remove debris such as garbage, organic residues, glass fragments, etc., and remove gravel with excessive particle size to improve washing efficiency and reduce washing costs.
Elution treatment: Mix and stir the contaminated soil with the eluent under a certain soil-to-liquid ratio. After the eluent extracts the soil pollutants, let it stand for solid-liquid separation. Solid-liquid separation can use methods such as filtration, sedimentation, and centrifugation.
Leachate treatment: The leachate containing pollutants is further processed to meet emission standards or recycling requirements. Leachate treatment can use precipitation, adsorption, electrolysis, evaporation, distillation, membrane separation, biological methods and other methods.
Soil backfill or transportation: Backfill the leached clean soil to the original location or transport it to other locations for soil reconstruction or other uses.
The advantage of ex-situ washing technology for contaminated soil is that it can effectively remove heavy metal pollutants in the soil, improve soil quality, and reduce risks to the environment and human health. In addition, this technology can be completed in a short time, is simple to operate, and has a relatively low cost. The disadvantage of ex-situ washing technology for contaminated soil is that it requires a large amount of eluting agent and leachate treatment, which may cause secondary pollution or pollutant transfer, and requires strict monitoring and management. Additionally, this technique destroys the structure and biological activity of the soil, requiring soil reconstruction and restoration.
Desen Environment believes that ectopic washing of contaminated soil technology is a commonly used soil remediation technology, but it also requires reasonable design and optimization and selection of appropriate soil washing remediation equipment based on the characteristics of specific contaminated sites and pollutants. To improve the repair effect and reduce the repair cost. At the same time, it is also necessary to combine other restoration technologies to achieve comprehensive restoration and utilization of soil.
