The role of (bio)surfactant sorption in promoting the bioavailability of nutrients localized at the solid-water interface

Bioavailability is herein defined as the accessibility of a substrate by a microorganism. Further, bioavailability is governed by (1) the substrate co ncentration that the cell membrane "sees," (i.e., the "directly bioavailabl e" pool) as well as (2) the rate of mass transfer from potentially bioavail able (e.g., nonaqueous) phases to the directly bioavailable (e.g., aqueous) phase. Mechanisms by which sorbed (bio)surfactants influence these two pro cesses are discussed. We propose the hypothesis that the sorption of (bio)s urfactants at the solid-liquid interface is partially responsible for the i ncreased bioavailability of surface-bound nutrients, and offer this as a ba sis for suggesting the development of engineered in-situ bioremediation tec hnologies that take advantage of low (bio)surfactant concentrations. In add ition, other industrial systems where bioavailability phenomena should be c onsidered are addressed. (C) 1999 Published by Elsevier Science Ltd on beha lf of the IAWQ. All rights reserved.