Effluent standards have become more and more stringent due to an increase in awareness about environmental impacts on both continuous and intermittent polluting discharge. For that, a high efficient waste water treatment plants are needed to be designed. Membrane bioreactor (MBR) can be good solution to cope with such issues. MBR systems respects the conventional activated sludge process which use microorganisms for degradation of organic pollutants and requires aeration as well as reduced foot print and sludge production through maintaining a high biomass concentration in the bio reactor. The present work elucidates the recent patents and critically reviews the advancement in MBR process, which can be helpful to designer. It was found that the behavior of aeration device, mixed liquor suspended solids (MLSS) concentration, flux enhancer and handling of sludge plays an important role in the performance of MBR process.