Application of tubular ceramic ultrafiltration membranes for the treatment of integrated textile wastewaters

Membrane technologies have emerged as one of the best suitable alternatives for the management of highly polluted effluents generated in the textile industry processes. These technologies are capable either of being used as a pre-treatment or to achieve complete water reclamation, depending on the process involved. This study evaluates the performance of tubular ceramic ultrafiltration membranes treating integrated raw effluents from a textile mill, at different operating conditions (transmembrane pressure, pH, and molecular weight cut-off).A joint effect from the studied operating conditions was observed. Consequently, the process efficiency varied considerably depending on the combination of operating conditions. The permeate flux increased with pressure up to pseudo-stable values for higher pressures. However, for the lowest tested pH, permeate flux rates were enhanced with pressure up to a maximum beyond which flux might decrease. The increase in the applied pressure lead to a compression of the particles rejected onto the membrane surface, which was enhanced by the lower electrostatic repulsive forces. In general, higher membrane fouling rates were observed for the highest cut-off as well as for the highest applied pressures. Significant pollutant load removals were achieved with noteworthy values for the chemical oxygen demand (>70%), color (96%) and turbidity (>93%). The results prove the suitability of the treatment in terms of permeate quality for either disposal or later final treatment aiming at the reclamation of these waste streams.

► Ceramic UF membranes are a suitable pretreatment of polluted textile effluents.
► Selection of the operating conditions is critical in the UF process performance.
► Higher permeate flux rates are obtained with TMP until a maximum is reached.
► Lower feed pH involves more permeable and more compressible cake layers.
► High pollutant removals were achieved in terms of organic load, color and turbidity.