Influence of Side Stream Supersaturated Aeration Technology on Membrane Fouling and Azithromycin Removal in a Membrane Bioreactor

A bench scale membrane bioreactor (MBR) fed synthetic wastewater was operated under two different aeration systems to assess the effect of a side stream super oxygenation system (SDOX). Particularly, the effects of this aeration system on the biological performance of organic matter removal and nitrification along with membrane fouling, and azithromycin removal were assessed. Four different experiments were carried out by changing some operational conditions including mixed liquor suspended solids (MLSS) concentration, aeration types, membrane flux, and the presence of azithromycin as a micro-pollutant in the influent. The MBR was operated for approximately 15 days with fine bubble diffusers followed by SDOX. The negative effect of the high pressure on the organic matter removal and nitrification was insignificant. The effect of SDOX on other sludge characteristics was noticeable: the particle size of the sludge floc decreased (44-64%), whereas the diluted sludge volume index (DSVI) increased. Hydraulic retention time was found to have a greater impact on membrane fouling than the high pressure effect. Regarding the azithromycin removal efficiency, the SDOX had a detrimental impact on the overall removal efficiency of azithromycin.