Interactions between BTEX Compounds during their Anoxic Degradation

Benzene, toluene, ethyl-benzene and o-xylene degradation was evaluated under anoxic denitrifying conditions. These aromatic hydrocarbons were supplemented as single carbon sources or in dual or quaternary mixtures in order to identify key interactions during the degradation process. The results showed that toluene, together with ethyl-benzene, were the most readily biodegradable compounds under anoxic conditions among the aromatic compounds and their combinations tested. However, ethyl-benzene degradation time was significantly increased when combined with toluene as carbon source. Both benzene and o-xylene demonstrated to be highly recalcitrant compounds for anoxic denitrification, their degradation being rapidly inhibited likely as a result of the accumulation of toxic metabolites excreted during the degradation process. In this sense, mineral medium renewal was required to achieve complete degradation of these pollutants. Any combination of the aromatic compounds revealed an inhibitory interaction during the biodegradation process, an increase in the biodegradation time and therefore a decrease in pollutant degradation rates being observed upon addition of more than one compound.