(328g) Foam Recovery of Biosurfactants From Fermenters

Biosurfactants are naturally occurring amphiphiles with potential for use as alternatives to traditional petrochemical and oleochemical surfactants. The unique properties of biosurfactants, including their biodegradability and tolerance of a wide range of temperature and pH, make their use in a range of novel applications attractive. Currently the wider ultilisation of biosurfactants is hindered by a lack of economic production routes, with downstream processing presenting a significant challenge.

A novel apparatus design has been developed for continuous recovery of extracellular biosurfactants from fermenters. The design allows for the operating conditions of the foam fractionation process, feed rate and airflow rate, to be chosen independently of the fermentation parameters. Optimal conditions can then be established for each process, such as the aeration rate required to meet the biological oxygen demand of the cell population. The recirculating foam fractionation process was tested on HFBII producing fermentations. It is shown that by using foam fractionation to strip HFBII from fermentation broth in situ the amount of uncontrolled overflowing from the fermenter was greatly reduced compared to fermentations without foam fractionation. Through optimisation of the foam column operating conditions the proportion of dry matter retained in the fermenter was increased from 88 % to 95 %, in contrast to a dry matter retention of 66 % for fermentation without the new design. With the integrated foam fractionation process a HFBII recovery of 70 % was achieved at an enrichment of 6.6. This work demonstrates the utility of integrated foam fractionation in minimising uncontrolled foaming in fermenters whilst recovering an enriched product. This integrated production and separation process has the potential to facilitate improved biosurfactant production, a major barrier to their wider use.