Purification of bioactive compounds from blackberry pomace: Investigation of techniques to reduce fouling during flat membrane ultrafiltration process

Abstract

Here we evaluated the use of static turbulence promoters of different pin diameters and ultrasound during the ultrafiltration of the blackberry pomace extract. The steady state fluxes during ultrafiltration of blackberry extract pomace through a polymeric 10 kDa membrane under ultrasound irradiation and with turbulence promoters with pins of 2.5 and 3.5 of diameters were 3.12 ± 0.08, 6.00 ± 0.14 and 4.02 ± 0.36 L h−1 m−2, respectively. The steady state flux under conventional ultrafiltration was 2.22 ± 0.12 L h−1 m−2. Cake formation was more effectively mitigated with the turbulence promoters than with ultrasound, since turbulence promoters provided the formation of effective secondary flows, while the ultrasound waves were not able to effectively remove the compressed cake layer. The permeate flux was greater with the turbulence promoter of pins with diameters of 2.5 mm than of 3.5 mm at the same specific energy consumption. The ultrafiltration process retained almost 80% of the bioactive compounds from the blackberry pomace extract and the applied devices did not significantly change the characteristics of the permeate extract. Thus, the use of turbulence promoters with pins of small diameters is recommended to improve the permeate flux during ultrafiltration process.