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Greenhouse gas emissions and the links to plant performance in a fixed-film activated sludge membrane bioreactor – Pilot plant experimental evidence

Mannina, Giorgio, Capodici, Marco, Cosenza, Alida, Di Trapani, Daniele, Olsson, Gustaf
Bioresource technology 2017 v.241 pp. 1145-1151
activated sludge, air flow, dissolved oxygen, fouling, greenhouse gas emissions, greenhouse gases, membrane bioreactors, nitrous oxide
The present study explores the interlinkages among the operational variables of a University of Cape Town (UCT) Integrated Fixed Film Activated Sludge (IFAS) membrane bioreactor (MBR) pilot plant. Specifically, dedicated experimental tests were carried out with the final aim to find-out a constitutive relationship among operational costs (OCs), effluent quality index (EQI), effluent fines (EF). Greenhouse gas (GHG) emissions were also included in the study. Results showed that the EQI increases at low flow rate likely due to the dissolved oxygen (DO) limitation in the biological processes. Direct GHGs increase with the increasing of the air flow due to the anoxic N2O contribution. Irreversible membrane fouling reduce from 98% to 85% at the air flow rate of 0.57m3h−1 and 2.56m3h−1, respectively. However, the increase of the air flow rate leads to the increase of the N2O–N flux emitted from the MBR (from 40% to 80%).