A systematic review of moving bed biofilm reactor, membrane bioreactor, and moving bed membrane bioreactor for wastewater treatment: Comparison of research trends, removal mechanisms, and performance

The various detrimental effects of wastewater generated from different anthropogenic activities are among the biggest challenges to sustainable development. Among various technologies developed to tackle wastewater, biological treatment methods, such as moving bed biofilm reactor (MBBR) and membrane bioreactor (MBR), have been extensively used in the past few decades due to their cost-effectiveness, wide applications, technical feasibility, etc. However, certain limitations of MBR and MBBR have led to the hybridization of these two technologies. In this context, a thorough bibliometric assay of MBBR, MBR, and hybrid moving bed membrane bioreactor (MBMBR) has been performed to analyze the current trends in publication, contributing authors and countries, major research hotspots, etc. It was observed that for both MBBR and MBR, China had the maximum contribution, i.e., 30.4% and 30.5%, respectively, in terms of the number of publications. The future trend of the selected treatment methods was assessed with the help of S-curve simulation. In both cases, greater than 70% of research articles were published in the last decade, which may be due to the increasingly stringent regulations on effluent quality. Subsequently, this study investigated the performance and responsible mechanisms for these systems. MBMBR was found to be more effective than MBR in terms of pollutant removal, followed by MBBR. The nutrient removal efficiency of MBMBR systems was significantly higher (73.5%) as compared to MBBR (50%) and MBR (62.5%). Life cycle assessment (LCA) has been discussed for the selected treatment methods to evaluate sustainability aspects.