Azo dyes, are aromatic compounds with one or more azo (-N=N-) groups. They are most important and largest class of synthetic dyes used in industrials applications. They are considered xenobiotic compounds that are very recalcitrant to biodegradation processes because many are made from carcinogens such as aromatic amines and phenols being released into the environment. The presence of these dyes in the aquatic ecosystem causes environmental and health concerns.The great numbers of industries that use dyes, applies conventional biological treatment called activated sludge, which efficiently removes organic matter, but are ineffective for dyes degradation. In anaerobic conditions, decolourization occurs, but the parental aromatic amines and and other toxic compounds can released. In this work, the toxicity and mutagenic of azo dyes and their degradation products will be investigated. For this, the decolorization process will be investigated. For this, the decolorization process will be performed in an anaerobic-aerobic system inoculated with bacterial strains previously isolated from an industrial effluent containing azo dyes. The samples will be tested after biological treatment, and the ones that are still toxic and or mutagenic will be further treated by Advanced Oxidation Processes. The decolourization and biodegradation of azo dyes and the metabolites produced will be monitored by UV-vis, Chemical Oxygen Demand (COD) and High Performance Liquid Chromatography and Mass Spectrometry (HPLC-MS) respectively.The toxicity and mutagenicity tests will be carried out after and before treatment, using organisms from different trophic levels to investigate possible effects of these compounds and their metabolites when released into environment. Thus, this project aims to contribute to the research that is being performed in the thematic project, because biological treatment is the main choice of the industriesand maybe the addition of oxidative processes at the end will be a cost effective option providing the aimed mineralization of azo dyes.
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