In a recent study on tannery effluents, Gallego-Molina et al.(2012) reported that reversible resistance due to cake formation could be removed by back washing, whereas irreversible fouling required a chemical washing. Our study confirmed that for the UF membranes studied, irreversible resistance represented only 1–5% of the total resistance. Therefore, performing a chemical cleaning was not justified considering the major operational and environmental drawbacks.