EFFICIENCY OF DIFFERENT AERATION SYSTEMS IN FULL SCALE MEMBRANE BIOREACTORS

In membrane bioreactors (MBRs) for municipal wastewater treatment the secondary clarifier is replaced by a membrane filtration. In comparison with the conventional activated sludge process MBRs offer the advantage of a smaller footprint due to higher biomass concentrations and a complete removal of solids from the effluent. As submerged configured MBRs operate with an additional coarse bubble aeration system for fouling control the total energy consumption of MBRs is about twice to fourth as much as in conventional plants. Investigations of the oxygen transfer rate (OTR) and standard aeration efficiency (SAE) in two existing full scale MBRs were performed at different MLSS with both aeration systems respectively. The SAE of the “crossflow” coarse bubble aeration system for fouling control is about three times lower than the fine bubble aeration system which provides oxygen supply. Thus for limitation of energy consumption the “crossflow” aeration should be used only for fouling control.