This article mainly introduces the in situ biogas technology of soil remediation technology in contaminated sites.
Biological ventilation method is a forced oxidation of in situ biodegradation method. That is forced into the contaminated soil air, volatile organic matter together and then discharged into the gas processing unit for subsequent treatment or directly into the atmosphere. This method is often used in the upper part of the groundwater layer is better permeability of volatile organic compounds contaminated soil repair, but also applies to loose porous soil structure, in order to facilitate the growth and reproduction of microorganisms.
Generally, before aeration is used to treat the soil, first of all, two or more wells should be drilled in the contaminated soil. When air is aerated, a certain amount of nitrogen is added as a nitrogen source for growth of the degrading bacteria to improve the treatment effect. In contrast to vacuum extraction of soil steam, it uses a lower air flow rate and only provides enough oxygen to maintain microbial activity. Oxygen is supplied to the soil for residual contamination by direct air injection. In addition to degrading adsorbed contaminants, volatile compounds are biodegraded as the air flows slowly through the bio-active soil.
The technology is characterized by:
(1) The presence of water levels within a few feet of the surface, saturated soils, or low permeability soils can affect biological ventilation.
(2) Lower soil moisture content may limit biodegradation and ease of drying soil to affect the effectiveness of biological aeration.
(3) This technology has been successfully applied to soils contaminated with petroleum hydrocarbons, non-chlorinated solvents, certain pesticide preservatives and other organic chemicals.
(4) The soil structure of the site has a great influence on this technology.
The repair cost of this technology is 55-300 $ / m3, the repair cycle is 6-24 months, the pollutants that can be removed are non-halogenated volatile organic compounds, non-halogenated semi-volatile organic compounds, fuels . Pollutant removal rate> 90%.
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