Packed cage rotating biological contactor for mustard tuber wastewater treatment: Performance and microbiome along the axial direction

Abstract

Due to the alternate exposure of the biofilm to wastewater and air, the rotating biological contactors (RBCs) provide a changing biofilm external environment for microbiome growth. In this study, a novel packed cage rotating biological contactor (PCRBC) system, with more artificially intensified biofilm and higher oxygen mass transfer efficiency, was applied to treating mustard tuber wastewater (MTWW). The capacity and kinetics of pollutants removal was evaluated based on Monod Equation and Illumina MiSeq techniques were used to detect the spatial distribution of microorganism community along the flow pathway. The results illustrated that the PCRBC has a good performance on COD, NH4+-N and TN with removal efficiencies over 90.49%, 99.12% and 70.82%, respectively. The bacterium community populations at the middle and distal end of the PCRBC train were completely different from those at the beginning of the PCRBC. However, the strong ecological associations were observed among different bacteria. Except for conventional denitrification pathway, the heterotrophic nitrification-aerobic denitrifying (HN-AD) combined with short-cut denitrification was inferred as the main denitrification pathways, especially at the middle and end of the PCRBC. This study presents a novel perspective to interpret the resilience of the PCRBC through the deeper analysis of the bacterium community dynamics which was supposed to help guiding optimization strategies for more effective pollutant removal.