Recent advances in application of moving bed biofilm reactor for wastewater treatment: Insights into critical operational parameters, modifications, field-scale performance, and sustainable aspects

The increase in the generation of wastewater along with the presence of different recalcitrant pollutants has stressed the existing conventional biological treatment systems beyond capacity. Given the necessity of advanced biological treatment processes, moving bed biofilm reactor (MBBR) is preferred for treating high organic and nutrient load and recalcitrant contaminants with enhanced removal efficiency, less footprint, reduced operational difficulties, and increased technical feasibility for large-scale as well as package-based-unit implementation. The present review attempts comprehensive documentation on the application of the MBBR process, its advantages and disadvantages, and comparative analysis with other advanced biological processes. The influencing design and operational parameters, such as hydraulic retention time, filling ratio of carriers and wastewater in the reactor, aeration, biofilm thickness, etc., have significant effects on the performance of MBBR. Furthermore, some modifications/up-gradation of the MBBR are analyzed targeting the enhanced nitrification and denitrification, organic matter removal, reduction of cost during the operational phase, etc. Among them, modification of biocarriers, aeration techniques, hybridization of MBBR with other biological and physicochemical processes exhibited promising performance concerning the removal of organics and nutrients. The present review also highlighted the areas of further research on the MBBR based-systems, their sustainability aspects, and subsequent field-scale applications.