| Summary: |
Soil contamination is closely related with inadequate practices of some industrial activities, disposal of industrial and municipal wastes or environmental accidents. Just only a small amount of an organic compound is enough to contaminate big volumes of soil and groundwater, till levels of contamination higher than those imposed by law, turning the situation more serious when the pollutants are toxic or even carcinogenic.
The criteria that support remediation decisions have as objective the use of the soil and the use of groundwater as source of drinking water. In situ technologies are more advantageous considering economical aspects.
One of the most used in situ technologies is soil vapour extraction (SVE). It is simple, relatively cheap and very efficient to remove volatile organic compounds (VOCs), usually due to underground fuel sumps. The most important limitation of this and others technologies is the incapacity to preview rigorously the time remediation according to clean-up goals. The available methodologies for estimations of the remediation time are not enough safe, conducting sometimes to erroneous previsions that can lead to the implementation of expensive and inefficient remediation processes.
Aiming to reach a further understanding of this subject, this project has as main objectives: i) to study the behaviour of pollutants (kinetic and equilibrium) in soils prepared with different characteristics in what concerns to the granulometrie distributions and to sand, clay, natural organic matter and moisture contents; ii) to perform soil on the prepared soils analysing the influence of soil characteristics on the remediation time; iii) to obtain a model based on artificial neural networks to predict the remediation time of contaminated soils, through their physico-chemical characteristics; iv) to integrate simple mechanistic models with artificial neural networks to predict SVE remediation times; v) to proceed to vapour extractions of real contaminate  |
Summary
Soil contamination is closely related with inadequate practices of some industrial activities, disposal of industrial and municipal wastes or environmental accidents. Just only a small amount of an organic compound is enough to contaminate big volumes of soil and groundwater, till levels of contamination higher than those imposed by law, turning the situation more serious when the pollutants are toxic or even carcinogenic.
The criteria that support remediation decisions have as objective the use of the soil and the use of groundwater as source of drinking water. In situ technologies are more advantageous considering economical aspects.
One of the most used in situ technologies is soil vapour extraction (SVE). It is simple, relatively cheap and very efficient to remove volatile organic compounds (VOCs), usually due to underground fuel sumps. The most important limitation of this and others technologies is the incapacity to preview rigorously the time remediation according to clean-up goals. The available methodologies for estimations of the remediation time are not enough safe, conducting sometimes to erroneous previsions that can lead to the implementation of expensive and inefficient remediation processes.
Aiming to reach a further understanding of this subject, this project has as main objectives: i) to study the behaviour of pollutants (kinetic and equilibrium) in soils prepared with different characteristics in what concerns to the granulometrie distributions and to sand, clay, natural organic matter and moisture contents; ii) to perform soil on the prepared soils analysing the influence of soil characteristics on the remediation time; iii) to obtain a model based on artificial neural networks to predict the remediation time of contaminated soils, through their physico-chemical characteristics; iv) to integrate simple mechanistic models with artificial neural networks to predict SVE remediation times; v) to proceed to vapour extractions of real contaminated soils evaluating the applicability of the developed models.
The global goal is to develop a methodology for forecasting the remediation time using SVE based on the soil characteristics, to be possible a previous evaluation of the process viability.
The project considers the remediation of soils mainly constituted by sand, day and organic matter, contaminated with COVs (Benzene, Toluene, Xylene, Ethylbenzene, Trichloroethylene and Tetrachloroethylene). Gas chromatographic methodologies will be developed for the quantification of pollutants and process monitoring. SVE experiments will be performed in a projected pilot installation, using vacuum pumps to produce airflow. |