Article révisé par les pairs
Résumé : Membrane separation is an emerging technology for secondary effluent (SE) recycling as an alternative water source. However, SE contains secondary metabolites which form a film on membrane surfaces, leading to a decrease in hydraulic capacity. This is an extensive study of the effect of fouling on UF performance, with a detailed analysis of foulants composition and morphology, and the evaluation of the most effective – either physical or chemical – UF membrane regeneration methods. The paper also investigates FNA (recycled from WWTPs) as an alternative acidic UF membrane cleaning agent. In the UF-DE mode, the most effective backwashing configuration was 1 s every 1 min, where relative membrane permeability decreased by 54% after 4-h, which indicated the presence of physically irreversible fouling after SE separation. An acidic-alkaline cleaning procedure in which the contribution of irreversible fouling was 13% resulted in a 100% efficiency of UF membrane regeneration. The results confirmed that recycled FNA is as efficient as pure reagent-nitric acid V and that the use of FNA can reduce the costs of chemical cleaning by 60%. To fit in with the idea of the circular economy, we proposed a new strategy of reusing spent acidic solutions as an alternative fertiliser.

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