Ultrafiltration of xanthan gum fermentation broth: Process and economic analyses

Energy consumption and operating costs for xanthan recovery from dilute fermentation broth using ultrafiltration and alcohol precipitation were studied. Ultrafiltration can be used to concentrate xanthan fermentation broth from 2.5 to 15% (w/v) xanthan. The effects of xanthan concentration, transmembrane pressure difference and shear and pumping rates on the performance of ultrafiltration were studied. Engineering design equations for modelling filtrate flux and pressure drop during ultrafiltration of xanthan broth were also developed and used in the process analysis. The optimal conditions for maximum filtrate flux, minimum membrane costs and minimum energy costs were determined. It was found that up to 80% of the energy used in recovering xanthan gum from fermentation broth can be saved by using ultrafiltration to concentrate the broth before alcohol precipitation. (C) 1997 Elsevier Science Limited.