Raphaëlle Savoire

Comparative study of ultrasound-assisted and conventional stirred dead-end microfiltration of grape pomace extracts

Ultrasound (US) was used to facilitate dead-end microfiltration (MF) of grape pomace (GP) extracts. The effects of ultrasonic power, sonication cycle time and ultrasonic probe height on filtration behaviour were investigated. Ultrasonic irradiation had a strong impact on the MF processes, especially with high output power and continuous mode. A comparative study of US-assisted and stirred MF was performed. The energy consumption and liquid flux enhancement of the two filtration systems were compared. Under the same dissipation power, the flux enhancement is much higher for the US-assisted MF. A correlation equation for predicting permeate flux was derived from resistance-in-series model. The flux predictions were confirmed with the experimental results. Finally, the characteristics of permeate after US-assisted and stirred filtration were evaluated.

Effect of Disruption Methods on the Dead-End Microfiltration Behavior of Yeast Suspension

High voltage electrical discharges (HVED) and high pressure homogenization (HPH) were compared for extracting intracellular compounds from yeasts. The efficiency of cell disruption was evaluated by measurements of electrical conductivity, UV-spectroscopy, etc. It was shown that the HPH permits better extraction than HVED. The filtrations of yeast suspension were studied in a dead-end stirred cell. The filtration of untreated, HVED and HPH treated yeast suspensions without stirring was governed by cake formation mechanism. The filterability of HVED and especially HPH-treated yeast suspension was very low. Under stirring, different filtration mechanisms were observed for untreated and treated yeast suspensions.

Effect of Phospholipids on Crude Linseed Oil Filtration

Abstract Lecithin addition (0 to 10%) in crude linseed oil was used to investigate the effect of phospholipids on oil filtration at 20°C. The addition of lecithin (more than 2%) results in a decrease in the filtration rate, an increase in the cake resistance, and a modification of the filtration mechanism from cake resistance to intermediate blocking. At 20°C the lecithin precipitated on the particles and caused sedimentation of a deposit impermeable to oil that slows down the oil flow through the cake. The magnetic stirring is not an efficient way of filtration improvement on the contrary of filtration at 50°C.