The University of Massachusetts Amherst
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Monod kinetics for aerobic biodegradation of petroleum hydrocarbons in unsaturated soil microcosms

TitleMonod kinetics for aerobic biodegradation of petroleum hydrocarbons in unsaturated soil microcosms
Publication TypeJournal Article
Year of Publication2007
AuthorsOstendorf DW, Schoenberg TH, Hinlein ES, Long SC
JournalEnvironmental Science and Technology
Start Page2343
Date Published03/2007

We use Monod kinetics to calibrate previously published data that document the aerobic biodegradation of hydrocarbon vapors in soil microcosms from a weathered petroleum spill site. Monod kinetics offer insight into biodegradation mechanics because they address biomass growth as well as substrate depletion. A blend of five aromatics and five alkanes dose the microcosm sets at four strengths, and a finite difference model describes the response superimposed across the constituent substrates. An observed initial biomass XO of 125 g biomass/m3 soil moisture and an endogendous decay rate b of 0.102 day-1 calibrate all four dosages and agree with heterotrophic plate counts. Common maximum specific growth rates μMJ and half saturation constants KSJcalibrate each constituent across the four dosages. The biodegradable alkanes exhibit μMJ values ranging from 0.0190 to 0.0996 day-1, while the aromatic rates vary from 0.0946 to 0.322 day-1. One of the alkanes (2,2,4-trimethylpentane) is recalcitrant. The half saturation constants range from 0.000083 to 0.000355 g substrate/m3 soil moisture for the biodegradable alkanes, which imply zero-order kinetics. The aromatic KSJ values vary from 5.02 to 14.3 g substrate/m3 soil moisture, and suggest first-order kinetics. The yield YJ increases with dosage concentration for all the biodegradable constituents, varying from 0.0533 to 1.58 g biomass/g substrate.