Abstract:
Polycyclic aromatic hydrocarbons (PAHs) are known to be resistant to environmental degradation due to their
hydrophobicity which results in low solubility in water. PAHs are therefore typically less bioavailable than other
non-aromatic compounds in the same range of molecular weight. One of the PAHs, fluoranthene, is a four-ring
PAH rated among the top 16 PAHs which are included in the list of priority pollutants by the U.S.EPA. Like
other PAHs, fluoranthene is a mutagenic, carcinogenic and toxic compound with known potential risks to
human health and the environment. In this study, cultures of biosurfactant producing bacteria were isolated
from engine oil contaminated soil at a car servicing facility in Pretoria (South Africa). Biodegradation of
fluoranthene was conducted using the isolated culture in two Continuous Stirred Tank Reactors (CSTRs) in
series followed by polishing treatment in a packed-bed biofilm reactor. Optimum operation times for the CSTR
and biofilm system was based on the optimum incubation time and experimental results from batch systems.
Results showed that up 93 % fluoranthene was degraded during runs that utilised the enriched inoculum from
engine oil contaminated soil. The open system was easily optimised based on target feed rate, hydraulic
retention time (HRT) and biomass yield. Analysis of the 16S rRNA gene of the biosurfactant producing
inoculum showed that the strains isolated were 100 % homologs of Pseudomonas aeruginosa.
