Performance and microbial community analysis of combined bioreactors in treating high-salinity hydraulic fracturing...

The anoxic/oxic systems are a widely used biological strategy for wastewater treatment. However, little is known about the performance and microbial community correlation of different combined bioreactors in the treatment of high-COD and high-salinity hydraulic fracturing flowback and produced water (HF-FPW). In this study, the performance of Up-flow anaerobic sludge bed-bio-contact oxidation reactor (UASB-BCOR) and Fixed-bed baffled reactor (FBR-BCOR) in treating HF-FPW was investigated and compared. The results suggested the FBR-BCOR could efficiently remove COD, SS, NH₄⁺-N, and oil pollutants, and it exhibited better resistance to the negative interference of hydraulic shock load on it. Besides, the correlation analysis first disclosed the key functional genera during the degradation process, including Ignavibacterium, Ellin6067, and Zixibacteria. Moreover, network analysis revealed that the difference of microbial co-occurrence network structure is the main driving factor for the difference of bioreactor processing capacity. This work demonstrates the feasibility and potential of FBR-BCOR in treating HF-FPW.