Whey protein fouling of large pore-size ceramic microfiltration membranes at small cross-flow velocity, J. of Membrane Science
Έτος : 2008
Author : Mourouzidis-Mourouzis S.A. and Karabelas A.J.
Permeate ﬂux decline in dead-end microﬁltration of whey protein isolate solutions is studied, using disc-type ceramic membranes of nominal pore size 0.8 m. The tests involve ﬁve successive ﬁltration cycles, under ﬁxed ﬁltration pressure, with intermediate backwashing. Flux decline analysis and membrane resistance are employed to determine fouling mechanisms, with respect to applied pressure, in the range 2.5–10 psi. Permeate and retentate concentration data complement the permeation rate measurements. Both irreversible and reversible fouling is identiﬁed for the backwashing mode employed. Data interpretation suggests that more rapid fouling, as well as signiﬁcant surface-layer “compaction” effects may occur at the higher pressures employed. There is evidence that irreversible fouling effectively develops during the ﬁrst cycle of the tests (of 30 min duration) and apparently does not signiﬁcantly increase later on; however, reversible fouling occurs through the entire ﬁltration series, being more intense during the ﬁrst minutes of each cycle. The effect of protein aggregates is investigated with the aid of DLS measurements and ﬁltration tests with preﬁltered solutions; it appears that whey protein aggregates present in the solution, are responsible (almost entirely) for the observed membrane fouling. An effective membrane cleaning procedure is proposed. Finally, the possible advantage of operating large-pore size MF (for the process considered) at rather low pressure is suggested.