Air sparging of a submerged MBR for municipal wastewater treatment

The performance of a submerged tubular membrane bioreactor (MBR) adopting two coarse bubble aeration (sparging) modes is reported. In the first mode, air is injected to the membrane tube channels so that mixed liquor circulates within the bioreactor (air-lift mode). In the second mode, the membrane lumen is subjected to intermittent sparging (air-jet mode). The performance in each case was evaluated against primary municipal wastewater effluent (settled sewage'). The flux was found to increase by 43% when aeration was introduced to the air-lift module. No further flux increase was observed on increasing the gas flow from 1 to 10 1 min(-1). The air-jet module performance was constrained by clogging due to slow accumulation of sludge inside the lumen, which was not completely ameliorated by the action of the air jet. On applying a periodic backflush to remove the accumulated matter, the permeability attained from the air-jet aerator exceeded that of the air-lift module. (C) 2002 Elsevier Science Ltd. All rights reserved.