Soils contaminated with hexavalent chromium : sorption, migration and remediation

The interest in environmental soil science has been growing in the last years due to the continuous degradation of this major natural resource. In this work, a representative sample of a typical loamy sand soil was collected in Porto, Portugal, in a zone of intensive agriculture activity. This soil was used for a series of tests concerning the adsorption, transport and fate of hexavalent chromium. The adsorption equilibrium and sorption kinetics were evaluated through the fitting of several mathematical models to the batch and flow experimental data. Generally, the results revealed a high retention of chromium for low pH values. Then, the application of a novel technique, comprising an electrochemical and a biological component was tested in the cleaning of soil contaminated with hexavalent chromium. Removal values of 60% and 79% were obtained with zeolite and activated carbon biobarriers, respectively. This work is integrated in a PhD thesis that pretends to be a tool for policies and decision makers, through the transport and fate studies, but also for the industrial sector aiming the development and application of the cleaning techniques explored