With government financial support, my country has carried out research and development of restoration technology and equipment for multiple types of sites. Although there are many remediation technologies for soil and groundwater pollution that can be listed, in fact, there are very few economical and practical remediation technologies. The commonly used soil remediation technologies are summarized as follows:
1. Thermodynamic remediation technology uses heat conduction, thermal blankets, hot wells or thermal walls, etc., or thermal radiation, radio wave heating, etc. to achieve the treatment of contaminated soil. of repair.
2. Thermal desorption remediation technology uses heating to heat the soil contaminated by organic matter to above the boiling point of the organic matter, so that the organic matter in the adsorbed soil volatilizes into a gaseous state and then is separated and processed.
Thermal desorption technology is one of the most advanced polluted waste treatment technologies in the world. The main treatment objects are pesticide-contaminated soil, oil field oily waste, tank bottom sludge, etc. Its working principle is to utilize the thermal instability of organic matter in polluted waste to achieve separation of pollutants and soil through non-incineration indirect heating, and to isolate the solid phase, oil phase, water phase and gas phase in the waste. Most of them are recycled and treated fundamentally harmlessly, so this technology is widely used in oilfield waste treatment operations around the world.
3. Incineration method, the contaminated soil is burned in an incinerator, so that high molecular weight harmful substances, volatile and semi-volatile, are decomposed into low molecular flue gas through dust removal, cooling and purification. The smoke meets emission standards.
4. Landfill method, using waste as a kind of slurry, applying sludge into the soil to adjust the nutrition, humidity and pH value of the soil through fertilization, irrigation, adding lime, etc. to keep pollutants in the upper layer of the soil. aerobic degradation. You can use a soil acidity meter to test the soil pH and humidity, and a soil EC meter to test the soil EC value to check the soil improvement effect.
5. Chemical leaching, with the help of chemical/biochemical solvents that can promote the dissolution or migration of pollutants in the soil environment, the eluent is injected into the contaminated soil layer under the action of gravity or through water head pressure. , and then extract the solution containing pollutants from the soil for separation and sewage treatment technology.
6. Composting method, using the traditional composting method to accumulate contaminated soil, mix the pollutants with organic matter, straw, wheat straw, wood chips and bark, feces, etc., relying on microorganisms in the composting process It can degrade refractory organic pollutants in soil.
7. Phytoremediation, the use of agricultural technology to improve the chemical and physical constraints of soil that are unfavorable to plant growth, making it suitable for planting, and directly or indirectly by planting preferred plants and their rhizosphere microorganisms Absorb, volatilize, separate and degrade pollutants, and restore and reconstruct the natural ecological environment and vegetation landscape.
8. The permeable reactive wall is an in-situ treatment technology that builds a permeable wall containing reactive materials in shallow soil and groundwater to remove the pollution from polluted water when it passes through the wall. The substances undergo physical and chemical reactions with the reactive materials in the wall and are purified and removed.
9. Bioremediation is a controlled or spontaneous process that uses organisms, especially microorganisms, to catalyze the degradation of organic pollutants, thereby repairing the polluted environment or eliminating pollutants in the environment. Among them, microbial remediation technology uses microorganisms, indigenous bacteria, foreign bacteria, and genetically engineered bacteria, to transform and degrade pollutants through their metabolic effects. It is mainly used for the degradation of organic pollutants in soil. By changing various environmental conditions such as nutrition, redox potential, and metabolic matrix, microbial degradation is strengthened to achieve the purpose of treatment.
Characteristics of various remediation technologies and applicable pollution types: Advantages and disadvantages of type remediation technology Applicable types Bioremediation Phytoremediation has low cost, does not change soil properties, does not cause secondary pollution, takes a long time, and the degree of pollution cannot exceed the remediation level The normal growth range of plants. In-situ bioremediation of heavy metal and organic matter pollution is fast, safe and low-cost. The conditions are strict and not suitable for treating heavy metal pollution. Ex-situ bioremediation of organic matter pollution is fast, safe and low-cost. The conditions are strict and not suitable for treating heavy metal pollution. In-situ chemical leaching for chemical remediation of organic matter pollution is long-lasting, easy to operate, and reasonably cost-effective. The depth of treatment is limited, and may cause secondary pollution such as heavy metals, benzene series, petroleum, halogenated hydrocarbons, polychlorinated biphenyls and other ectopic chemical leaching. Long-term washing performance, easy operation, unlimited depth, high cost, eluent treatment problems, secondary pollution heavy metals, benzene series, petroleum, halogenated hydrocarbons, polychlorinated biphenyls and other solvent leaching technology are effective and long-lasting. Effective, easy to operate, unlimited treatment depth, high cost, solvent pollution problem needs to be solved. In-situ chemical oxidation of PCBs and other polychlorinated biphenyls is effective, easy to operate, unlimited treatment depth. Narrow scope of use, high cost, possible existence Oxidants contaminate PCBs and other in-situ chemical reduction and reductive dechlorination, which are effective, easy to operate, and the depth of treatment is not limited. Narrow scope of use, high cost, possible oxidant contamination of organic matter. Soil performance improvement, low cost, good results. Scope of use Narrow and poor stability. The physical remediation of heavy metals. Steam leaching technology is more efficient and costly. It takes a long time. The VOC curing and remediation technology is more effective. It takes a shorter time and is more expensive. After treatment, it cannot be used again. Physical separation and remediation equipment of heavy metals is simple, low-cost and sustainable. The treatment sieve may be clogged, contaminated by dust, and suddenly the particle composition is destroyed. Heavy metals and other vitrification repairs are more efficient and costly. Organic matter and heavy metals cannot be used again after treatment. Thermodynamic repair efficiency is high and costs are high. Organic matter and heavy metals cannot be used again after treatment. Isothermal desorption remediation is more efficient and costly for organic matter, heavy metals, etc. Electrodynamic remediation is more efficient for organic matter, heavy metals, etc., and the cost is higher. The soil replacement method for low-permeability soil is more efficient and costly. Contaminated soil also needs to be treated with organic matter, heavy metals, etc. Although There are many soil remediation technologies, but no one remediation technology can target all contaminated soils. Similar pollution conditions, different soil properties, and different remediation needs will also limit the use of some remediation technologies. In addition, most remediation technologies bring more or less side effects to the soil.