  Microfiltration technology is a widely used engineering strategy for fresh
water production and water treatment. The major concern in many applications is
the formation of a biological fouling layer leading to increased hydraulic
resistance and flux decline during membrane operations. The growth of bacteria
constituting such a biological layer implicates the formation of a multispecies
biofilm and the consequent increase of operational costs for reactor management
and cleaning procedures. To predict the biofilm growth and evolution during the
filtration process, a one-dimensional continuous model has been developed by
considering a free boundary value problem describing biofilm dynamics and EPS
production in different operational phases of microfiltration systems. The
growth of microbial species and EPS is governed by a system of hyperbolic PDEs.
Substrates dynamics are modeled thorough parabolic equations accounting for
diffusive and advective fluxes generated during the filtration process. The
free boundary evolution depends on both microbial growth and detachment
processes. The proposed model has been solved numerically to simulate biofilm
evolution during biologically relevant conditions, and to investigate the
hydraulic behavior of the membrane. The model has been calibrated and validated
using lab scale experimental data. In all cases, numerical results accurately
predicted the membrane pressure drop occurring in the microfiltration system.
