Treatment of municipal wastewater by membrane bioreactor

Membrane bioreactor (MBR) technology became a significant technology for municipal and industrial wastewater treatment, because of its diverse benefits over conventional bioreactors. MBR has been considered as a simple, consistent and economical process with a substantial removal of contaminants for the treatment of municipal wastewater. However, a major problem in the operation of MBR is membrane fouling. There are numerous studies carried out to investigate the fundamental problem of fouling and the mechanisms behind it. Fouling reduces the lifetime of the membrane as well as a decline in permeate flux. The fundamental idea of fouling control is to clean the membrane when it is fouled. In this research, the performance of submerged MBR for municipal wastewater treatment as well as fouling reasons with their effects in MBR processes has been studied. It was found that greater sludge retention (SRT) time compared with HRT (9 hours) has increased the MLSS concentrations of the activated sludge. Certain analyses like COD, NH4 and PO4 were carried out to see the removal performance of the membrane where the average removal efficiency for COD, NH4 and PO4 were found to be 91.87%, 97.80% and 70.11% respectively. To investigate the sludge characteristics various experiments like hydrophobicity, sludge volume index (SVI), capillary suction time (CST) and also EPS and SMP were done during the study. Critical flux analysis, as well as SEM analysis on the membrane surface, were also carried out to see the effects of fouling in MBR. Less SMP and EPS production normally weakened biofilm formation ability but enhanced membrane filterability which is the main target of this study.