ABSTRACT Overview of the combination of an anaerobic membrane bioreactor with integrated ultrafiltration and the downstream ammonia removal using reverse osmosis or nanofiltration. RO exhibits higher energy consumption and better retention performance, while NF shows significantly lower energy consumption but also poorer retention performance. Nanofiltration (NF) is an energy-efficient alternative to reverse osmosis (RO) for partial ammonia removal and nutrient recovery. Within the EC SYMSITES project, this study evaluated NF performance for treating anaerobic membrane bioreactor effluents from meat-processing wastewater. Pilot-scale experiments were conducted at 20°C and 4–18 bar using spiral-wound NF and RO modules. The DuraSlick NF2540 membrane treated real effluents with conductivities up to 27 mS cm−1 and ammonium nitrogen concentrations up to 2,200 mg L−1. Ammonia retention increased with pressure for both membranes. NF achieved 60–80% ammonium rejection at 10 bar and pH ≈ 6 with significantly lower energy demand, while RO exceeded 95% rejection but at reduced flux. Acidification improved NH4− rejection due to the shift of the ammonia–ammonium equilibrium, although further pH reduction to 4.5 provided limited additional benefit while increasing chemical consumption. Ionic composition also affected performance: multivalent anions enhanced rejection, whereas monovalent salts reduced selectivity. NF removal efficiencies were consistent with literature values for complex effluents, but NF alone cannot meet stringent reuse limits. Overall, NF is a cost- and energy-efficient option for partial ammonia removal and is best combined with complementary treatment processes to achieve stricter standards.
Fuchs et al. (2026) studied this question.