Free Access
Volume 80, Number 1, January-February 2000
New applications of membrane technology in the dairy industry
Page(s) 155 - 163
DOI: 10.1051/lait:2000115

Lait 80 (2000) 155-163

Nanofiltration of sweet whey by spiral wound organic membranes: Impact of hydrodynamics

Romain Jeantet ${^{\rm a}}$, Jesus Rodríguez ${^{\rm b}}$, Anita Garem ${^{\rm b}}$

${^{\rm a}}$Laboratoire de technologie alimentaire, ENSAR, 65 rue de Saint-Brieuc, 35042 Rennes Cedex, France
${^{\rm b}}$Laboratoire de recherches de technologie laitière, INRA, 65 rue de Saint-Brieuc, 35042 Rennes Cedex, France


The influence of permeation flux J and wall shear stress $\tau_w$, on performances of the nanofiltration of concentrated sweet whey at volume reduction ratio 2, $18~^\circ$C and using organic membranes was studied. It was concluded that sweet whey nanofiltration could be optimised through the parameter $J/\tau_w$, since J and $\tau_w$ act together in a competing mechanism of convection/erosion at the membrane surface, that governs membrane fouling and selectivity. Hence, the overall fouling was strongly dependent on the ratio $J/\tau_w$, with a critical $J/\tau_w$ value of approximately 6.0. When $J/\tau_w < 6.0$, the total membrane fouling was relatively low and almost independent on operating conditions. For higher ratios of $J/\tau_w$, there was a spectacular increase in fouling and a very strong dependence between the fouling index and $J/\tau_w$. Simultaneously, selectivity was altered under these conditions, with higher retention of monovalent ions and lower retention of lactose. Finally, optimal hydrodynamic conditions were defined in the range 3-6. Under these conditions, longer operating times, lower chemical oxygen demand in permeate and higher demineralization could be expected at lower processing costs.

nanofiltration / hydrodynamic / sweet whey / fouling

Correspondence and reprints: A. Garem

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