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2 Environmental Biotechnology

2 2010

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Remediation of soils contaminated with trichloroethylene

Albergaria J. T., Alvim-Ferraz M. C. M., Delerue-Matos C. M.

Environmental Biotechnology

2010

Vol. 6, No. 2

37-41

Soil contamination is a common problem in our society. Several activities introduce contaminants in soils affecting their quality and future utilization. In order to invert this situation and to avoid further spreading of the contaminant several remediation technologies could be used. For soils contaminated with trichloroethylene (TCE), Soil Vapor Extraction (SVE) can be an efficient remediation technology. It involves the application of vacuum to the soil matrix creating an airflow that conduce the volatized contaminant to extraction wells that lead them to the exterior of the soil where they are properly treated. This work presents the results obtained in the soil vapor experiments performed in a laboratory using soils with different water contents contaminated with TCE. These experiments aimed the study of the influence of soil water content and the airflow used in the remediation time and on the process efficiency. The results showed that in sandy soils contaminated with TCE: a) for similar levels of contamination, the increase of the soil water content from 0 to 4% created an increase of the concentration of TCE in the gas phase of the soil, in some cases by almost 50%; b) the influence of water content is not significant being overlapped by influence of the airflow rate; c) SVE performed with higher airflow rates had shorter remediation times (in some cases four times shorter) without any significant impact on the process efficiencies (fluctuations of 1 to 3%); and d) for the experimented soils, the utilization of higher airflow rates led to shorter and consequently cheaper remediation.

Bioremediation of humic soils contaminated with benzene

Rosas M., Domingues V., De Marco P., Oliva-Teles T., Fiuza A., Albergaria J. T., Delerue-Matos C. M.

Environmental Biotechnology

2010

Vol. 6, No. 1

11-15

Bioremediation uses degradation capacity of indigenous or inoculated microorganisms to biodegrade organic constituents adsorbed to soils. It is a technology that generally requires long periods of treatment to reach the desired clean-up goals. The objectives of the reported work were to evaluate the capability of bioremediation to achieve legal clean-up goals in a humic soil with an organic matter content of 14% and contaminated with benzene. The benzene quantification was performed by gas chromatography. The results of the experiments were used to calculate process efficiency and remediation time. It was concluded that: a) the bioremediation is an effective process; b) bioremediation efficiencies were near 100%; and c) the remediation times were 92, 139 and 354 hours for soils contaminated with benzene levels of 70, 90 and 120mg*kg-1, respectively.