Biodegradation of gasoline: kinetics, mass balance and fate of individual hydrocarbons

The degradation of gasoline by a microflora from an urban waste water activ ated sludge was investigated in detail. Degradation kinetics were studied i n liquid cultures at 30 degrees C by determination of overall O-2 consumpti on and CO2 production and by chromatographic analysis of all 83 identifiabl e compounds. In a first fast phase (2 d) of biodegradation, 74% of gasoline , involving mostly aromatic hydrocarbons, was consumed. A further 20%, invo lving other hydrocarbons, was consumed in a second slow phase (23 d). Undeg raded compounds (6% of gasoline) were essentially some branched alkanes wit h a quaternary carbon or/and alkyl chains on consecutive carbons but cycloa lkanes, alkenes and C10- and C11-alkylated benzenes were degraded. The degr adation kinetics of individual hydrocarbons, determined in separate incubat ions, followed patterns similar to those observed in cultures on gasoline. Carbon balance experiments of gasoline degradation were performed. The carb on of degraded gasoline was mainly (61.7%) mineralized into CO2, the remain ing carbon being essentially converted into biomass.