Effects of periodic backflushing with filtrate on filtration performance in an internal-filtration bioreactor

Abstract

Periodic backflushing of tubular ceramic membrane filters with filtrate was employed to alleviate membrane fouling in a bioreactor with internal-filtration. As the model system, yeast fermentation was dealt with in this study. There existed optimum backflushing interval and time to give a maximum flux recovery. At 16 g/l of yeast cell concentration, the mean flux increased about 2.5 times by using such repeated operation cycles as consisted of 4.53 minutes for filtration, 4.5 seconds for intermission, and 40 seconds for backflushing. Effects of aeration, agitation speed, and yeast cell concentration were also investigated.

Reverse-flow diafiltration for continuous in situ product recovery

“…Park et al stated, that with yeast cell concentrations of more than 16 g/L more frequent backflushing intervals needed to be applied in order to operate the process effectively [9]. This is in agreement with the results presented here which show that permeabilities change when higher concentrations are used.…”

“…Suzuki et al [8] used two separate asymmetric ceramic tubes with independent connections to alternatingly use them for permeate recovery and air sparging, thereby ensuring constant permeability. Park et al used periodic backflushing with filtrate to operate an internal filter system also using tubular ceramic membranes [9]. Yeast model suspensions were used for finding an optimum backflushing interval and time for maximum flux recovery.…”

The capture and release of biomass using a high voidage fibrous filter (marked revision)

“…Additionally, biomass retention can be important in the separation of valuable biological material from aqueous streams (see e.g. Su et al, 1995;Park et al, 1997Park et al, , 1999Lee et al, 2000;Kobayashi et al, 2003). A feature common to both of these application modes is the desire to have complete control of the retention and removal of biomass in the separation stage.…”

A membrane stirrer for product recovery and substrate feeding

“…This set‐up filters large volumes without membrane clogging from retained cells. Since fouling during ISRP lowers filtration efficiency (Carstensen et al, ), different anti‐fouling concepts for individual bioreactors are currently being discussed in literature. Backflushing of fluids such as medium, filtrate, or air remove foulants from the membrane surface (Carstensen et al, ; Kamoshita et al, ; Park et al, ). Various backflushing techniques with different intervals and frequencies recover the product flux to its initial value (Carstensen et al, ; de Ven et al, ; Prip Beier and Jonsson, ; Suzuki et al, ).…”