Janus, T. and P. Paul, Water Software Systems, Faculty of Computing Sciences and Engineering, De Montfort University, UK
(free)Membrane bioreactors (MBRs) are a recent innovation in wastewater treatment that combines a membrane filtration unit with a biological process (Tchobanoglous et al. 2003).The focus of this study is only on membrane filtration. It concentrates on the development of a mathematical model describing filtration and fouling on micro-filtration membranes and this work is based on the earlier published model by Liang et al. (2006). Initial modelling experiments with the Liang model showed its deficiencies at predicting trans-membrane pressures over a wide range of membrane fluxes. A very basic structure of this model and its behavioural character limit its applicability to only limited number of operational regimes. In an endeavour to develop a more universal yet simple model, the Liang model has been extended and modified to include: backwash mechanism, cake and SMP deposit compressibility effects, various cake removal models (air scouring and cross-flow velocity) and flux dependent SMP deposition rates. The model was developed in MATLAB/Simulink environment and validated on experimental data from a flux stepping experiment performed on a pilot scale with a tubular crossflow 0.45m membrane. A second validation exercise was performed on long-term filtration data from a membrane pilot plant equipped with a hollow fibre 0.05 mm membrane. The model proved to be in good agreement with the measurements in both validation studies. Key Words Cake, Filtration, Fouling, MBR, Modelling, Simulation, SMP, Wastewater
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