Kinetic Modeling and Error Analysis for Decontamination of Different Petroleum Hydrocarbon Components in Biostimulation of Oily Soil Microcosm
2011
El-Gendy, Nour Sh | Farah, Joseph Y.
A microcosm study was constructed to investigate the effect of complex co-substrate (corn steep liquor, CSL) addition on indigenous bacterial community, rate and extent of petroleum hydrocarbons (PH) degradation in an oily soil with total petroleum hydrocarbons (TPH) content of 63353 mg kg⁻¹. TPH degradation was found to be characterized by a rapid phase of degradation during the first three weeks where 76% removal of TPH occurred, followed by a slower degradation phase, where further 7% of the initial TPH was removed by the end of incubation period, 35 d. Branched alkanes are more resistant to microbial degradation than n-alkanes. Furthermore, the unresolved complex mixtures (UCM) of hydrocarbons are less degradable than n- and iso-alkanes. Pristane (Pr) was the most recalcitrant aliphatic compound studied in this work. These results in addition to the extensive bacterial growth observed (from 10⁷ to 10¹⁰ CFU g⁻¹ soil) give strong support that the addition of CSL resulted in increased degradation rates. The indigenous bacteria grew exponentially during the incubation period of 35 d with a growth rate of 0.26 d⁻¹. Kinetic modeling was performed to estimate the rates of biodegradation of each hydrocarbon type component in the studied system. Five different error functions were used in this study to evaluate the fitness of the model equation to the obtained experimental data. This showed that the degradation of ∑nC₂₀-nC₂₄, ∑nC₃₅-nC₄₂ and nC₁₈ can be better represented by a second order model, whereas the TPH, total resolvable peaks (TRP), nC₁₇, UCM, ∑nC₁₀-nC₁₄, ∑nC₁₅-nC₁₉, ∑nC₂₅-nC₂₉, ∑nC₃₀-nC₃₄, ∑nCₙ, and ∑isoCₙ and isoprenoids Pr and phytane (Ph) were similarly following the first order model.
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