Classification of repair techniques 1. According to the disposal site: it can be divided into in-situ repair (in-situ) technology and ex-situ repair (ex-situ) technology. Simply put, it is whether to excavate or not. 2. According to the principle of restoration technology: it can be divided into biological, physical, chemical and physico-chemical restoration technologies. 3. According to the medium in which pollutants exist: it can be divided into soil remediation technology and groundwater remediation technology. 4. According to the "source-pathway-receptor" control method: it can be divided into polluted medium treatment technology, pollution pathway blocking technology and receptor protection technology Urban polluted soil remediation technology system project case 1. Exsitu solidification and remediation process of heavy metal contaminated soil 2. Organic matter contaminated soil Normal temperature desorption and low-temperature thermal desorption remediation process 3. Organic matter contaminated soil normal temperature desorption and thermal desorption remediation process: Simulation device 4. Advanced oxidative remediation process for organic matter contaminated soil 5. Polluted groundwater extraction-treatment and remediation process technology Research and development of contaminated soil enhanced washing-graded concentration and reduction technology The soil in the Yangtze River Delta is often more viscous and heavy, resulting in strong adsorption performance for pollutants., common eluants have poor desorption effect on pollutants, and solid-liquid separation is difficult during the elution process, so enhanced elution technology is needed; By classifying the particle size of contaminated soil, coarser components such as construction waste and sand are separated and applied as clean building materials and soil to achieve the purpose of reducing the amount of contaminated soil. Contaminated soil Foam barrier emergency treatment and restoration technology using foam as medium. Contaminated soil in legacy sites such as chemical plants and perfume factories often contains high concentrations of volatile organic pollutants (VOCs), which have a strong odor, causing peculiar odors to disturb the people. At present, for VOC-contaminated sites, China usually uses inflatable greenhouses and steel greenhouses to shield the soil. However, this technology has disadvantages such as high price, limited by the site, and easy damage and poor sealing of greenhouses. Can be replaced with foam barrier technology. An on-site pilot test has been carried out and the results are excellent. Research on the oxidative degradation of groundwater pollutants by self-activating persulfate slow-release columns 1. The state encourages in-situ technology;2. During the injection process of liquid reagents, slurry back is easy to occur;3. Persulfates require activating agents and often need to be injected multiple times;4. In order to avoid the above technical shortcomings, a self-activating persulfate slow-release column has been developed, which can be effective for a certain period of time when inserted underground without the need to add activating agents.