Anaerobic Digestion of Propylene Oxide/Methyl Tertiary Butyl Ether Manufacturing Wastewater Under Different pH-Regulation Modes and Comparison of Microbial Community Structures

摘要

In this study, anaerobic digestion was employed to degrade the refractory, high-salinity PO/MTBE (propylene oxide/methyl tertiary butyl ether) manufacturing wastewater (P/MMW) in sequencing batch mode. H2SO4 was added into the system to neutralize the alkalinity produced by the hydrolysis of sodium formate in P/MMW. The pH value in reactor A was only adjusted at the beginning of each cycle, and controlled in the range of 7.51-8.26. Meanwhile, the pH value in reactor B was maintained at 7.2 by regulating multiple times throughout the acclimation cycles. After five cycles of acclimation, both reactors exhibited stable removal of chemical oxygen demand (COD), while COD removal in system B was significantly improved in later stages (cycle III-V). More sulfate was reduced to sulfide alongside the COD removal process in reactor B, indicating more organic pollutants were removed by sulfate-reducing bacteria. High-throughput sequencing results illustrated that Firmicutes and other microorganisms capable of degrading the main pollutants in P/MMW were enriched to a greater degree in reactor B. Microbial communities in reactors A and B were different from seed sludge and evolved into two distinct groups, with sulfate and sulfide concentrations being main contributing factors for microbial community selection.