Bioremediation : validation of spectroscopic methods for the analysis of Cr 6+ internalisation and reduction of Cr 6+ to Cr 3+ by Pseudomonas alcaliphila

Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2014Hexavalent chromium is a toxic by-product of several industries. Contamination of soil and water with Cr(VI) is prevalent all over the world, but conventional processes used to remove heavy metals from the environment are expensive and often not as effective as desired. Bioremediation with heavy metal-resistant microorganisms is a cheaper and promising approach to removal of toxic metals from soil and water. In this thesis the Cr(VI)-reducing capabilities of Pseudomonas alcaliphila were tested by analysing surnatant samples of P. alcaliphila exposed to 3900 ppm and 7800 ppm of K2CrO4 for 24 hours. Analysis was done by F-AAS and UV techniques and required devising calibration methods for both techniques that fit changing experimental conditions. Results from several samples were largely inconclusive for both methods but seemed to suggest that Cr(VI) removal from the medium by P. alcaliphila might occur by different mechanisms and that one might be prioritised over the others by the bacteria. Results also seemed to suggest that those mechanisms might be employed cyclically. Although further investigation into Cr(VI)-removal mechanisms of P. alcaliphila is required, this species is a possible candidate for hexavalent chromium bioremediation