Volumetric oxygen mass transfer coefficient and surface tension in simulated salt bioremediation media

Toluene can be removed from contaminated sites via bioremediation. However, aeration and mixing must be optimized to ensure effective volumetric oxygen mass transfer coefficient (kLa). Such response was determined in different salt solutions, specifically basal saline medium, low saline medium, Bushnell-Hass medium and a medium simulating seawater, which were tested either as such, or supplemented with toluene as a model pollutant, or with glucose or yeast extract as carbon and nitrogen sources, or with surfactin as a biosurfactant. kLa values obtained at different agitation intensities and aeration rates were compared with those in water and correlated with power number and superficial gas velocity. Surface tension decreased when surfactin was added to toluene-containing media due to toluene-surfactin micelle formation. SeawaterThe seawater-simulating medium exhibited the highest surface tension reduction.