A bench-scale pilot plant was operated to evaluate the potential of using m
icrofiltration hollow fiber membrane modules as an air diffuser and solid/l
iquid separator in an alternate cycle within a bioreactor treating domestic
wastewater. Two modules capable of air backwashing were immersed in a bior
eactor. Compressed air backwashing and filtration by suction were effected
alternatively. The experimental results reveal that application of the air
backwashing technique to submerged membrane modules is capable of not only
declogging the membranes but also of aerating the mixed liquor. Thus, bette
r filtration flux rate and aeration without a separate aeration device were
attained simultaneously. It was also noted that the introduction of an ano
xic zone enhanced the removal of nitrogen. In addition, operation at low hy
draulic retention time with high sludge concentration and the absence of a
sedimentation tank indicate considerable savings on the plant area.