What Is Contaminated Land Remediation?

Remediation of contaminated soil refers to the use of physical, chemical, biological, and ecological principles and artificial control measures to reduce the concentration (activity) of soil pollutants, to achieve harmless and stable pollutants, to achieve the desired detoxification effect Technical measures. At present, theoretically feasible restoration technologies include phytoremediation, microbial restoration, chemical restoration, physical restoration, and comprehensive restoration. Some repair technologies have entered the field application stage and achieved good results. Remediation of contaminated soil is of great significance in blocking pollutants from entering the food chain, preventing harm to human health, and promoting the protection of land resources and sustainable development. At present, the research and development of this technology is mainly focused on the two major aspects of degradable organic pollutants and remediation of heavy metal contaminated soil.

1.Development of green and environmentally friendly soil bioremediation technology

Phytoremediation using solar energy and natural plant resources, microbial remediation of highly effective and obligate microbial resources in soil, animal remediation of food networks in different nutrient layers in the soil, and natural restoration based on integrated soil ecological functions monitored will be the 21st century soil environment restoration The main direction of scientific and technological research and development. Remediation technology for farmland soil pollution requires that the trace amounts of toxic and harmful pollutants that affect food production and the quality of agricultural products can be effectively removed in situ. At the same time, it can neither destroy soil fertility and ecological environmental functions, nor cause secondary pollution. The development of green, safe and environmentally friendly soil bioremediation technology can meet these needs and can be applied to the treatment of large areas of contaminated agricultural land. It has both technical and economic advantages. It has become a trend to screen suitable restoration varieties from conventional crops and develop rhizosphere ecological restoration technologies suitable for different soil types and conditions. The application of bioengineering technologies such as genetic engineering, enzyme engineering, and cell engineering to develop soil bioremediation technologies is conducive to improving the rate and efficiency of governance. Has application prospects.

2.Development of comprehensive soil remediation technology from single item to joint and hybrid

There are many types of pollutants in the soil, compound pollution is common, the type of pollution combination is complex, and the degree of pollution and thickness vary widely. There are many types of soil on the surface of the earth, and their composition, properties, and conditions have obvious spatial differences. Some sites not only have a wide range of pollution, different types of pollutants compound, soil and groundwater are contaminated at the same time, but also have different spatial planning requirements for soil reuse methods after remediation. In this way, it is often difficult for a single remediation technology to achieve the remediation goal, and the development of a comprehensive and integrated soil remediation model has become the research direction of site and farmland soil pollution remediation, such as the combination of different remediation plants and the combination of degrading bacteria and super-accumulating plants Restoration, fungal-repair plant combination repair, soil animal-plant-microbe combination repair, complex solubilization enhanced phytoremediation, chemical oxidation-biodegradation repair, electric repair-bioremediation, bio-enhanced steam leaching repair, photocatalytic nanomaterials Repair etc.

3.Development of soil remediation technology from ex situ to in situ

Excavating, transferring, stacking, purifying, and reusing contaminated soil is a commonly used off-site ex-situ repair process. This kind of ex situ repair not only has high processing cost, but also is difficult to treat sites with deep soil and groundwater contaminated. It cannot repair contaminated soil below buildings or contaminated sites next to important buildings. Therefore, it has become a trend in recent years to develop a variety of in situ repair technologies to meet the needs of different contaminated sites. For example, in-situ steam extraction technology, in-situ fixation-stabilization technology, in-situ bioremediation technology, in-situ nano-zero-valent iron reduction technology, and the like. Another trend is the development of in situ natural restoration based on monitoring to give play to the comprehensive ecological functions of the soil.

4.Development of soil remediation technology based on environmental functional remediation materials

Clay mineral modification technology, catalyst catalysis technology, nano-materials and technology have penetrated into the soil environment and agricultural production fields, and have been applied to the restoration of polluted soil environment, such as the use of nano-iron powder, titanium oxide, etc. to remove organic chlorine in polluted soil and groundwater Pollutants. However, the development and application of environmentally functional materials for target soil remediation have just begun. With development prospects. However, the distribution, response, behavior, fate, and ecotoxicology of these substances in the soil are still poorly understood, and it is difficult to scientifically assess their environmental safety and ecological health risks. The application conditions, long-term effects, ecological impacts, and environmental risks of soil remediation technology based on environmental functional restoration materials need to be answered.

5. Development of equipment-based rapid site remediation technology for contaminated soil

The application of soil remediation technology depends to a large extent on the support of remediation equipment and monitoring equipment. The equipment-based remediation technology is the basis for the marketization and industrialization of soil remediation. Utilization of plant resources after phytoremediation, preparation of microbial agents for microbial remediation, thermal desorption or steam extraction of organic contaminated soil, leaching or solidification of soil contaminated by heavy metals-stabilization, restoration process and environmental monitoring after restoration, etc. Requires equipment. Especially for the polluted sites left by the urban industry, due to its special location and the requirements for land redevelopment and utilization, fast and efficient physical and chemical restoration technologies and equipment are needed. It is a development trend to develop and apply rapid repair technology of contaminated soil based on equipment in the field. The penetration and application of some new physical and chemical methods and technologies in the field of soil environment restoration will accelerate the development of restoration equipment. For example, cold plasma oxidation technology may be

A promising technology for remediation of organic contaminated soil (unpublished data) will drive the development of new remediation equipment.

6.Development of soil remediation decision support system and post-evaluation technology

The decision support system for contaminated soil remediation is a tool for rapid screening of risk management and remediation technologies for contaminated sites. The screening of contaminated soil remediation technology is a multi-objective decision-making process, which needs to consider factors such as risk reduction, environmental benefits and remediation costs. Many European and American soil remediation research organizations such as CLARINET, EUGRIS, NATOPCCMS, etc. have systematically studied and summarized the management and decision support of contaminated sites. Some auxiliary decision-making tools such as document guidelines, decision-making flowcharts, and intelligent software systems have been introduced and developed one after another, and have been adopted during the specific site restoration process. Risk-based post-remediation assessment of contaminated soil is also an important part of the risk management of contaminated sites, including post-remediation pollutant risk assessment, remediation benchmarks, and evaluation of soil environmental quality. There are various types of soil pollution, and the contaminated sites are intricate and complex. The site-specific contaminated soil remediation decision support system and post-evaluation methods and technologies need to be developed ^[3] .