To alleviate problems of membrane bioreactors with membrane fouling control, the optimization of the
two-phased anaerobic mesophilic bioreactors coupling with the MS-PUFM system was evaluated. The
chemical oxygen demand (COD) removal efficiency of anaerobic sludge digestion with the MS-PUFM sys-
tem was raised from 40% to 97%. VFA concentration was sustained to be in the range 110–138 mg L
1
,
which was within the optimum range. In the methanogenic bioreactor, methane generation was
improved due to the effective reduction of methanogene washout with the MS-PUFM system, and the
optimum operating pressure of the MS-PUFM system resulted less than 3 kg
f
cm
2
. Mesh screen con-
tributed 20% decrease of operating cost and 33% increase of permeate flux from 10 to 15 L m
2
h
1
with
preliminary solids reduction. As a result, the MS-PUFM system showed practical feasibilities for the
digestion of sewage sludge, where current commercial system processes utilizing higher biomass density
are not appropriate.