What Is Soil Remediation?

Soil remediation is a technical measure to restore the contaminated soil to its normal function. In the soil remediation industry, there are more than 100 existing soil remediation technologies and more than ten commonly used technologies, which can be roughly divided into three methods: physical, chemical, and biological. Since the 1980s, many countries in the world, especially developed countries, have formulated and carried out contaminated soil treatment and restoration plans, so a new soil restoration industry has also formed.

Soil remediation refers to the use of physical, chemical, and biological methods to transfer, absorb, and reduce

The soil was originally a natural shelter and purification treatment place for various types of waste. When the soil receives pollutants, it does not mean that the soil is polluted. , Which has a harmful effect on hygiene and epidemiology, only to indicate that the soil is contaminated. There are many reasons for soil pollution, such as

From the perspective of industry development, since 2009, the growth rate of the environmental protection industry has accelerated significantly. Affected by this, the domestic soil remediation industry chain has also gradually entered an orderly and subdivided stage, forming from the detection of soil pollution projects to the risk assessment, to the implementation of remediation projects, and then the corresponding repair equipment vendors. Downstream industry value chain.

China's soil remediation market is still in its infancy. According to statistics, about 43.75% of China's soil remediation projects are small in scale and concentrated below 50 million. The proportion of relatively large-scale projects above 200 million accounts for only 18.75%. Compared with 30,283 and 80,700 contaminated sites in the United States and Europe, respectively, the number of sites that have been restored in China does not exceed 200. The soil remediation market is still in its infancy, but it is developing well.

According to the "2016-2020 China Soil Remediation Industry Development Prospects and Investment Forecast Analysis Report" released by the China Economic Future Research Institute, the national soil remediation contract contracted amount reached 2.128 billion yuan in 2015, an increase of 1.274 billion yuan from 2014.67 %. The number of companies engaged in soil remediation business in the country has increased to more than 900, which has nearly doubled from about 500 companies in 2014. In 2015, there were more than 100 national soil remediation projects. A number of high-precision repair techniques such as soil leaching, in-situ heating, and microbial chemical reduction have been used in soil and groundwater remediation projects. ^[6]

The market structure of China's soil remediation industry has also begun to take shape: state-owned enterprises represented by Beijing Construction Engineering Remediation have won major large-scale projects in the Beijing area; private remediation companies mainly based on Hangzhou Dadi Environmental Protection and Beijing's high-energy era share the Yangtze River Delta Small and medium-sized projects in other places;

In March 2011, the State Council specifically approved the "Implementation Plan for the Treatment of Heavy Metal Pollution in the Xiangjiang River Basin", which is the first and only pilot scheme for heavy metal pollution treatment officially approved by the State Council so far, with a total investment of 59.5 billion yuan. As of September 2012, Yongqing Environmental Protection has repaired more than 92,000 cubic meters of contaminated soil, becoming the "main force" for the management of heavy metal pollution in the Xiangjiang River.

Four development directions: (1) in the direction of decision-making, shift from total pollutant-based control to pollution risk assessment; (2) technically, from single repair technology to multi-technology combined in-situ repair technology, Comprehensive and integrated engineering repair technology; (3) On equipment, from ex-situ repair of fixed equipment to in-situ repair of mobile equipment; (4) In application, development of multiple pollutants compound or mixed contaminated soil Integrated remediation technology; from a single site to an oversized site; from the development of a single remediation technology to the simultaneous soil and groundwater remediation of multiple technologies and multiple facilities for simultaneous monitoring of the atmosphere and water. Six development directions: (1) green and environmentally friendly bioremediation technology; (2) comprehensive repair technology from a single to joint / hybrid; (3) repair technology from ectopic to in situ; (4) based on environmental functions Repair materials (nano) repair technology; (5) rapid site repair technology based on equipment; (6) decision support system for soil repair and post-repair evaluation technology.

With the financial support of the government, China has carried out research and development of repair 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 few economic and practical remediation technologies. There are several commonly used soil remediation technologies:

1. Thermodynamic repair technology, using heat conduction, thermal blankets, thermal wells or hot walls, or heat radiation, radio wave heating, etc. to achieve the repair of contaminated soil.

2. Thermal desorption repair technology, which heats the soil contaminated with organic matter above the boiling point of organic matter in a heating manner to volatilize the organic matter in the adsorbed soil into a gaseous state before separation and treatment.

With people's attention to environmental issues and the advancement of modern agriculture, pesticide microbial remediation technology will play a greater role in the control of pesticide environmental pollution, but there are also the following problems in the remediation process: microbial remediation research has achieved a lot in the laboratory Ideal results, but the results are often not as expected when applied to soil pollution sites, or even contrary to laboratory results; during the test, microorganisms are greatly affected by the outside world; in many cases, the pollutants cannot be completely degraded, which may Intermediates are produced, and sometimes the toxicity of the intermediate is greater than that of the parent compound. In future research, microbial remediation technology for soil pesticide pollution should be strengthened from the following aspects: Screening, collection, and protection of microbial resources for pollution remediation. Study on the degradation pathway and metabolic mechanism of pesticides by microorganisms. Strengthen the research on pesticides with high residues, great harms, and complex structures (such as heterocyclic rings) and new pesticide degradation pathways; strengthen the research on the co-metabolism mechanism involved in pesticide pollution remediation. On the basis of degrading gene screening and genetic engineering, accelerate the construction of efficient repair strains. Establish a scientific and reasonable bioremediation evaluation index system. Accelerate the application of theoretical research to the transformation of actual production results. Research on the interaction of environmental microorganisms in the ecological environment and joint repair with other environmental organisms. The joint application of microbial repair technology and other environmental pollution treatment technologies. Research on molecular biology and molecular ecology of bioremediation microorganisms. ^[9]