Comparison of a deterministic and a data driven model to describe MBR fouling

Abstract

Membrane bioreactors (MBRs) are a combination of activated sludge bioreactors and membrane filtration, enabling high quality effluent with a small footprint. However, they can be beset by fouling, which causes an increase in transmembrane pressure (TMP). Modelling and simulation of changes in TMP could be useful to describe fouling through the identification of the most relevant operating conditions. Using experimental data from a MBR pilot plant operated for 462days, two different models were developed: a deterministic model using activated sludge model n°2d (ASM2d) for the biological component and a resistance in-series model for the filtration component as well as a data-driven model based on multivariable regressions. Once validated, these models were used to describe membrane fouling (as changes in TMP over time) under different operating conditions. The deterministic model performed better at higher temperatures (>20°C), constant operating conditions (DO set-point, membrane air-flow, pH and ORP), and high mixed liquor suspended solids (>6.9gL-1) and flux changes. At low pH (<7) or periods with higher pH changes, the data-driven model was more accurate. Changes in the DO set-point of the aerobic reactor that affected the TMP were also better described by the data-driven model. By combining the use of both models, a better description of fouling can be achieved under different operating conditions

The research leading to these results has received funding from the Spanish Ministry of Economy and Competitiveness (CTM201238314-0O2-01 and PCIN-2013-074) and from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme FP7/2007-2013, under REA agreement 289193 (SANITAS). This publication reflects only the authors' views and the European Union is not liable for any use that may be made of the information contained therein. M.D was granted by the Spanish Ministry of Economy and Competitiveness (BES-2010033288)