Monod Kinetics for Aerobic Biodegradation of Petroleum Hydrocarbons in Unsaturated Soil Microcosms

• Published in: Environmental science & technology 2007-04, Vol.41 (7), p.2343-2349
• Main Authors: Ostendorf, David W, Schoenberg, Theodore H, Hinlein, Erich S, Long, Sharon C
• Format: Article
• Language: English
• Subjects: Applied sciences; Bacteria, Aerobic - growth & development; Bacteria, Aerobic - metabolism; Biodegradation; Biodegradation, Environmental; Biological and physicochemical properties of pollutants. Interaction in the soil; Biomass; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Hydrocarbons; Kinetics; Models, Chemical; Petroleum - metabolism; Pollution; Pollution, environment geology; Soil - analysis; Soil and sediments pollution; Soil Microbiology; Soil Pollutants - metabolism; Soil sciences; Soils
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es062313l

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 X O 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 μ MJ and half saturation constants KSJ calibrate each constituent across the four dosages. The biodegradable alkanes exhibit μ MJ 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.