| Abstract
| - Recent work has shown that a fraction of a contaminantsolubilized in the micellar phase of some nonionic surfactantsis directly available for biodegradation, meaning that thecontaminant can be transferred directly from the core of themicelle to cell without having to transfer to the waterphase first. This study extends the understanding of thebioavailability of the micellar phase for a single compoundto a multicomponent system of contaminants. Biodegradation experiments were conducted with binary and ternarymixtures of naphthalene, phenanthrene, and pyrene inthe presence of a nonionic surfactant, Triton X-100. A mixedbacterial culture, isolated and enriched from a PAH-contaminated soil at the Wurstsmith Air Force Base, MI,was used for the biodegradation experiments. In the absenceof the surfactant and at surfactant concentrations belowcmc, the multisubstrate Monod kinetics adequately simulatedthe biodegradation kinetics of the binary and ternarymixtures. In the multicomponent systems, as in singlesolute systems, the solutes in the micelle were found tobe directly bioavailable, and the bioavailability of eachcompound in the micellar phase decreased with increasingsurfactant concentration. For a given surfactant concentration, the bioavailability was higher for the lower molecularweight PAHs. There was little difference in the bioavailabilityof the same compound as a single solute or in differentbinary and ternary mixtures. To predict the bioavailabilityof the micellar phase substrates, a mass transfer-basedmodel was formulated that describes the transfer of substratefrom the micellar phase to the microorganisms. Thepredictions matched the experimental observations well,indicating the validity of the model and its potential forapplications in remediation designs.
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