Water reuse from wastewater: comparison between membrane bioreactor and ultrafiltration process

This study compares two different pilot plant configurations treating real wastewater to produce water for agricultural irrigation scope. The two configurations (Configuration I and II) operating in parallel have the same biological treatment unit. Specifically, the biological treatment occurs in an Integrated Fixed Film Activated Sludge – Intermittent Aeration (IFAS-IA) reactor. For Configuration I, the solid/liquid separation occurs through a membrane bioreactor (MBR). While, for configuration II a settler is devoted to the solid/liquid separation, followed by a tertiary ultrafiltration unit. During the plant operation, monitoring of the treatment performance coupled with the permeate quality according to the EU 741/2020 regulation was performed. Further, the nitrous oxide (N2O) emission has been measured, and the carbon footprint and the reclaimed water quality index (RWQI1) have been quantified. Results showed that Configuration I provided the best results in terms of both RWQI1 and carbon footprint. In terms of RWQ1, Configuration I provided 0.62 kg pollutant/year, while Configuration II was 0.43 kg pollutant/year. Regarding carbon footprint, the lowest value (0.38 gCO2eq/m3) was obtained from Configuration II due to the reduced membrane fouling.