E. Tardieu et al., Influence of hydrodynamics on fouling velocity in a recirculated MBR for wastewater treatment, J MEMBR SCI, 156(1), 1999, pp. 131-140
Membrane fouling within membrane bioreactor (MBR) applied to wastewater tre
atment was studied under adequate recirculation conditions, for which fouli
ng was only caused by soluble and colloidal fractions of the biological sus
pension. Four different activated sludges under steady-state biological con
ditions were tested under a wide range of hydrodynamic conditions (U=2-5 m/
s; Re=3000-20000; J=40-250 l/h m(2)). With constant filtration conditions,
the increase in hydraulic resistance with time (dR/dt) was measured as the
"fouling velocity", and this varied according to hydrodynamic and biologica
l conditions. Two different models were established to describe this influe
nce, in the form of ln partial derivative R/theta t = p - q chi. The first
model, with the hydrodynamic parameter chi = Re(0.8)tau(0)/rho J(2), was ba
sed on an energy comparison between the shear forces, represented by tau(0)
, and the kinetic energy linked to the permeation flux described by rho J(2
). The second one, with chi = Re-1.3/J d(h), was based on a description of
the mass transfer around the membrane, using equations based on adimensiona
l parameters. (C) 1999 Elsevier Science B.V. All rights reserved.