Long-term operation of continuous high cell density culture of Saccharomyces cerevisiae with membrane filtration and on-line cell concentration monitoring

Abstract

An internal membrane-®ltration bioreactor system with periodic fouling removal and on-line cell measurement was employed for long-term continuous ethanol production from glucose in order to prove its performance and practicality. The bioreactor system developed in this study was successfully operated for 2 months with no problems in the maintenance of ®ltration ux. The maximum productivity obtained in this study was about 13 g/l-h which was ca. 3.3 times higher than that obtained in a conventional chemostat without cell retention by membrane. In another run of continuous culture, the laser turbidimeter used for the on-line monitoring of cell concentration showed a stable performance for 45 days without sensitivity loss due to fouling.

Very high ethanol productivity in an innovative continuous two-stage bioreactor with cell recycle

“…The best experimental results reported so far have been obtained from single-stage chemostat systems with a membrane module [6,7]. With a microfiltration system, Groot et al [5] demonstrated that the ethanol productivity could be increased to 55 g l À1 h À1 with concomitant ethanol and glucose concentrations of 53 and 183 g l À1 , respectively.…”

“…This ethanol productivity was very high, but such a configuration may be unrealistic for industrial implementation since substrate cost represents 60% of the global cost. Park et al [7] succeeded in the total glucose conversion: a maximum ethanol productivity about 13 g l À1 h À1 was reported with an ethanol concentration of 43 g l À1 . Combining industrial criteria such as ethanol titre, ethanol productivity and residual substrate concentration, the performance reported here is one of the highest mentioned in the literature.…”

Reverse-flow diafiltration for continuous in situ product recovery

“…With increasing agitation speed the flux also increased. In a later publication the long term behavior of the concept was investigated [10] and the operation was successfully operated for about two months.…”

Separation of volatile compounds from fermentation broth by membrane distillation

“…The fermentation problems can be solved to a considerable degree by decreasing the amount of stillage, which can be achieved by using the membrane bioreactors for ethanol production 8,9 . The membrane separation retains yeast cells in the bioreactor, which facilitates the ethanol distillation from the obtained filtrate.…”