The Application of MBR for the Treatment of Municipal Wastewaters at Short SRT

The objective of this work is to compare the performance and fouling characteristic in a membrane bioreactors (MBR) operated at three different short sludge residence times for nitrification of a synthetic wastewater. The results shown the MBR were capable of achieving an average 90% removal of NH₄⁺-N and 95% removal of COD, almost independent of SRT. At longer SRT, concentrations of MLSS and MLVSS in the bioreactor increased accordingly, whereas the ratios of MLVSS/MLSS decreased. The dehydrogenase activity results indicated that decreased sludge age could increase the microbial activity in the MBR. Analysis of EPS and SMP showed that the protein, carbohydrate, TOC and DNA concentrations all decreased with increasing SRT, indicating that the membrane fouling potential decreased as SRT increased. The Protein and carbohydrate were the main part of SMP and occupied around 93% in all MBRs. All resistance (R, RM, RC, RF) increased as SRT decreased. Fouling resistance (RF) was the main resistance in MBR which value and proportion in total resistant all increased as SRT decreased.