Oxygenic biodegradation of BTX in aqueous matrices: evaluation of the parameters of the operation

Abstract

Selected native aerobic strains able to grow in the presence of volatile aromatics compounds in aqueous matrices were isolated and identified at the Biotechnology laboratory of the Instituto Colombiano del Petróleo ICP. These strains were obtained from water and soil samples contaminated with benzene, toluene and xylenes isomers (BTX), these consortia was capable of reducing BTX concentrations to acceptable international environmental standards. Operational parameters such as temperature, BTX initial concentration, dissolved oxygen (DO) and nutrient content, were evaluated, as they relate to removal rate of BTX in batch systems. These operational conditions will be used to determine the kinetics of removal and the parameters required for the scale-up pilot to plant and industrial size reactors. Operational conditions for the aqueous matrices included saturation of oxygen, temperature (305 K) and pH (6,5) control in an hermetic bioreactor. BTX total concentrations were reduced from 1 70 g·m-3 to 0,3 g·m-3 in less than ten (10) hours with a maximum removal rate of 26,27 g·m-3·h-1 . The removal rate was reduced to 0,745 g·m-3·h-1 for initial BTX concentrations of 5 g·m-3. Benzene showed the highest removal rate (1 5,80 g·m-3·h-1) followed by toluene (6,41 g·m-3·h-1 ). Xylene isomers exhibit the lowest biodegradation rates, ranging from 1,80 g·m-3·h-1 for the o-xylene to 0,85 g·m-3·h-1 forthe p-xylene.