Membrane bioreactor operated under intermittent aeration a comprehensive comparison with an IFAS-MBR: A pilot plant experience

This study presents a comparison of two advanced wastewater treatment technologies operating under intermittent aeration (IA): the Membrane Bioreactor (MBR) (Period I) and the Integrated Fixed Film Activated Sludge (IFAS)-MBR (Period II). Both technologies were applied to a pilot plant at the Water Resource Recovery of Palermo University and operated to remove carbon and nutrients from real wastewater. The ultimate goal was to provide a comprehensive comparison in terms of: carbon, nitrogen and phosphorus removal, nitrous oxide (N2O) emissions, membrane fouling, and carbon footprint. Results showed a better performance in nitrogen processes for IFAS-MBR during Period II. Total nitrogen removal efficiencies were 76 % and 83 % for Period I and II, respectively. The total N2O emissions were 1.7 % and 0.38 % for Period I and II, respectively. Conversely, the carbon footprint increased during Period II due to a higher membrane fouling rate and sewage sludge production of 2.5 and 2.8 kgCO2,eq m−3 for Period I and II, respectively. The experiments confirmed the beneficial role played by the biofilm in terms of the reduction/mitigation of N2O emissions.