Biodegradation of n-eicosane and VOCs: Cometabolism in a marine consortium

Abstract

Several batch scale assays were performed in order to establish a correlation between the microbial removals of neicosane, in presence of different concentrations of volatile organic compounds (VOCs) which showed a partial removing.
The selected VOCs were toluene and benzene. Results with benzene showed that the removal of this aromatic compound
was decreased in presence of n-eicosane and the lowest removal was obtained when VOC concentration was higher. The
removal of hydrocarbon was increased when VOC concentration was increased. In the assays with toluene, n-eicosane
reached a higher removal when VOC concentration was increased, but the aromatic compound showed a decrease in its
elimination dynamics. Control assays performed with VOCs at 28 mg/L without hydrocarbon showed higher removal
dynamics for benzene than toluene. Also control assays of n-eicosane at two different concentrations but without any
VOC showed that its removal dynamic decreased in the absence of the aromatic compounds for both assays. The kinetic
adjustrnent obtained for toluene (Hill kinetic model) showed that the removal rate of this compound increased while its
concentration at water-phase was higher. Although, when it was used a concentration of 50 mg/L or higher, the removal
rate became almost constant. For benzene, the higher removal rate was reached with 38 mg/L. With higher concentration,
the kinetic model showed inhibition, so the adjustrnent analyses fitted for a Monod kinetic model. n-Eicosane showed a
better adjustrnent with the Haldane kinetic model with an initial concentration of 188 mg/L for the highest removal rate.