Clarification of the Cardoon (Cynara cardunculus) Blanching Wastewater by Ultrafiltration—Study of Membrane Fouling and Flux Recovery after Chemical Cleaning

Abstract

This study focused on the clarification of real blanching wastewaters from the industrial processing of cardoon, a plant rich in polyphenols and belonging to the artichoke family (Cynara cardunculus). The aim of this study was to evaluate the performance of ultrafiltration (UF) as an initial clarification step prior to a subsequent nanofiltration treatment for the recovery and fractionation of polyphenols from these wastewaters. In this UF process, three commercial UF membranes with different pore sizes: 3 kDa, 15 kDa, and 50 kDa. The assessment of the clarification process was based on two key factors: permeate flux and the concentration of phenolic compounds. The membrane with a MWCO of 3 kDa was excluded as a potential UF membrane due to its limited performance in terms of permeate flux. The 15 kDa membrane showed comparable results in terms of cumulative flux to the 50 kDa membrane. However, further evaluation based on fouling index and water permeability recovery favored the 15 kDa membrane, indicating better performance. To gain insights into the flux decline mechanisms and understand membrane fouling, a study was conducted on the 15 kDa and 50 kDa membranes. The analysis revealed that the cake filtration model provided the best fit for both membranes. The study highlights the potential of UF membranes, specifically the 15 kDa membrane, for the clarification of cardoon blanching wastewater.