Study of membrane fouling using synthetic model solutions in UF and NF processes

One of the main drawbacks for the application of membranes technologies to the treatment of textile effluents is the fouling. Fouling phenomenon causes a flux decline and reduces the quality of the treated water. Previous studies have pointed at dyes that remain in the water after rinse processes, as one of the fouling agents. In this study several UF and NF membranes were tested using three synthetic reactive dyes solutions as feed streams. The influence of applied transmembrane pressure (TMP) on normalised flux, color, COD and salt retentions was studied. The extent of fouling phenomenon was evaluated in terms of filtration resistance (R-s/R-t ratio) and normalized flux also with TMP. The obtained results showed that R-s/R-t for NF and 1 kDa membranes were not nearly affected by TMP, except for 10 kDa one. In these cases R-s/R-t ratio was lower than 0.5 showing a negligible fouling phenomenon. Similar tendency was observed with the normalized flux results. For the 10 kDa one, the normalized flux decreased progressively with TMP reaching a total normalized flux reduction of 60%. (C) 2011 Elsevier B.V. All rights reserved.