• KSBB Journal
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• v.16 no.4
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• pp.403-408
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• 2001

Distillation condensate generated from downstream processing of microbial alcohol fermentation imposes a serious burden to biological wastewater treatment or anaerobic digestion due to its high contents of SS (suspended solids) and TN (total nitrogen), A pilot scale microfiltration of the stillage condensate with a stainless steel SCEPTER membrane of 0.1 ${\mu}$m pore size was carried out to remove SS which was mostly composed of microbial cell residue. A stable permeate flux was achieved when the decanter effluent containing 0.7% of SS was filtered under the conditions of X10 VCR (volume concentration ratio), 2.5 bar of TMP (transmembrane pressure), and 60$^{\circ}C$. When stillage condensate with 2.6% SS was treated directly with microfiltration, VCR below X3 was recommended for a long duration of filtration. The permeate and retentate obtained from microfiltration were recycled to make-up medium of fermentation. Adding permeate or retentate up to 30% of fermentation volume showed no distinguished undesirable influence during the course of alcohol fermentation. Although only slight improvements in the final amount of CO$_2$ evolution and alcohol content were observed, fermentation rate increased so that the required time to reach 450 L/ton of CO$_2$ evolution was shortened to 72% of that with normal media.