Advanced Numerical Tools Applied to Geo-environmental Engineering - Soils Contaminated by Petroleum Hydrocarbons, a Case Study

Abstract

Contaminated soils can be considered as a heterogeneous, anisotropic and discontinuous geo-system, whose properties vary in time and space. Focusing on the remediation of a real contaminated site (a refinery located in northern Portugal), soil samples contaminated with petroleum hydrocarbons were subject to laboratory studies. The results of contaminant degradation kinetics tests led to the development of a distributed parameter model describing simultaneously the time evolution of biomass and contaminant degradation. Several phenomena were globally taken into account in this model: the volatilization, a fast kinetics component, a slow kinetics component and the refractory hydrocarbons for the time scale used in the experiments. To complement kinetics tests the soil contaminated was submitted to respirometric tests. The a priori unpredictability of the respirometric results justified the continuous measurement of oxygen and carbon dioxide concentrations and of temperature in the soil atmosphere, resulting in a huge volume of data. Several mathematical techniques were used in respirometry data treatment, namely: time series, system identification and wavelets theories.