1. technical name

In-situ chemical oxidation and intelligent control restoration technology in organically contaminated sites.
2. scope of application
In-situ remediation of soil and groundwater in organically contaminated sites containing chlorinated organic compounds, polycyclic aromatic hydrocarbons, petroleum hydrocarbons and other organic pollutants.
3. technical content
3.1 technical principle
This technology uses stirring or high-pressure rotary spraying methods to add slow-release and high-efficiency oxidizing agents to contaminated areas of soil or groundwater in batches and types according to the concentration gradient of pollutants, and finally achieve oxidative degradation. for general (Exceeding the "Soil Environmental Quality and Construction Land Soil Pollution Risk Control Standards (Trial)"(GB36600 -2018) Standard screening value 0~ 2 times) Organic contaminated soil and groundwater, using self-developed alkali-activated sulfur-based chemicals; For ultra-high concentration (more than twice the standard screening value of GB 36600-2018) organically contaminated soil and groundwater, Fenton reagent modified by small molecule organic acids and chelating agent (EDTA-2Na) and activated persulfate agents are used for complex restoration, using activated and released free radicals to form a dual oxidation system to enhance oxidation capacity and degrade organic pollutants. In the process of remediation construction, simulation calculation is carried out by using multi-source mixed noise monitoring parameters in water environment to obtain optimal process operation conditions, and the intelligent control of remediation process and technology is realized while transforming pollutants in soil or groundwater into nontoxic or relatively less toxic substances. The technology can reduce the dosage of chemicals by 15%, and the degradation rate of some chlorine-containing organic compounds can be increased by 20%.

3.2 main innovations

(1) A strong oxidative repair agent with high retention characteristics has been developed. The oxidation performance is enhanced by forming a dual oxidation system with multiple free radicals, and the retention performance of the agent is improved by using small molecule organic acids and chelating agents, expanding the pH application range of the agent and improving oxidation. Degradation efficiency.
(2) In-situ and ex-situ chemical oxidation repair equipment has been invented to achieve precise repair through the "precise injection-migration and slow-release-enhanced oxidation-extraction treatment" process and the periodic operation mode of hydraulic cycle.
(3) A kinetic model for the degradation of organic pollutants driven by mixed noise was constructed, which revealed the influence mechanism of multi-source mixed noise on the degradation process of organic pollutants in the water environment, and invented a hydraulic cycle process based on risk-cost two-level management. Optimize technology to achieve dynamic and precise control.
4. Pollution control or environmental restoration effects
After restoration, the concentration of organic pollutants in soil, soil and groundwater reaches the GB36600 -2018 screening value, the Class III water quality limit value of the Groundwater Quality Standard (GB/T 14848-2017) or the on-site restoration target value. When the initial concentration of related pollutants is between 5mg/kg and 5000mg/kg, the removal rate is 70% and 90%.
5. Technology demonstration
This technology has been applied in 25 projects, with a total amount of approximately 373,000 m3 of earth to be repaired and approximately 43,000 m3 of groundwater to be repaired. Among them, the soil remediation project of Gaotai Road plot in Xiqing District, Tianjin has a remediation area of 11,017.1 m2 of organically contaminated soil, a remediation depth of 5m, and a remediation amount of 34,964.5 m3. The main soil remediation factors are TPH aliphatic hydrocarbons C6-C8, C8-C10 and aromatic hydrocarbons C8-C10; The groundwater restoration area is 10139m2, and the restoration volume is 35,486.5 m3. The groundwater restoration factors are mainly TPH aliphatic hydrocarbons C8-C10, C10-C12 and C12-C16, and the restoration objects are shallow groundwater. After restoration, the soil and groundwater meet the requirements of national standards. The extracted groundwater is treated to meet the third-level standard of Tianjin City's Comprehensive Sewage Discharge Standard (DB12/356-2018) and then discharged into the local municipal drainage pipe network.
6. investment estimation
Taking the soil remediation project of the Gaotai Road plot in Xiqing District, Tianjin as an example, the total investment is 43.0861 million yuan, of which fixed asset investment is 1.9135 million yuan.
7. investment recovery period
Taking the soil remediation project of Gaotai Road plot in Xiqing District, Tianjin as an example, the static investment payback period of the project is 3.26 years.
8. Prospects for transformation and promotion of technological achievements
In recent years, my country has fully implemented the "retreat from the city and enter the park" strategy for industrial enterprises located in urban areas. Now about 90% of pesticide and other production enterprises have relocated or are moving to industrial parks, leaving a huge number of organically contaminated sites to be repaired and reused. This technical achievement not only solves the problem of remediation and treatment of contaminated sites containing pesticides, chlorinated organic compounds, benzene derivatives and petroleum hydrocarbons, but also has promotion and application value for the remediation of contaminated sites in coking, dyes, medicine, petrochemical and other industries.