As shown in Fig. 1, each SAnMBR system consisted of a 5-L
completely mixed anaerobic reactor coupled with a 1-L gas
lifter, in which a submerged plate and frame membrane
module with a membrane surface area of 0.059 2 m2 was
installed. This design of having the membrane unit external to
the anaerobic rector allowed ease of membrane cleaning and
replacement while maintaining a strictly anaerobic environment
in the bioreactor at all time. The membrane module was
fabricated by mounting 2 pieces of PES microfiltration (MF)
membrane (GE Osmonics, pore size 0.45 mm), with one on each
side, on an acrylonitrile butadiene styrene (ABS) risen plate.
Three peristaltic pumps (Masterflex, L/S) were individually
used to feed influent into the anaerobic reactor, recycle mixed
liquid from the anaerobic reactor to the gas lifter and withdraw
permeate from the membrane module. Produced biogas
was recycled by a diaphragm gas pump (KNF, NMP850) to
scour the membrane surface for fouling control via an air
diffuser (located below and inline with the membrane plate).
Membrane fouling would be indicated by an increase in the
normalized trans-membrane pressure (TMP) which was
recorded by a digital pressure switch (SMC, ZSE50F) installed
between the membrane module and the permeate pump and
was normalized by deducting initial TMP from temporal TMP.
Biogas production was measured according to the volume of
biogas collected in the wetted gas collector, in which the gas
pressure was maintained at 1 atm pressure. A conductancetype
point level controller was applied to balance the influent and effluent fluxes, and a pH controller (ETATRON, HD-PH/P)
was used to maintain the pH at 7.0 0.5.