Leveraging Emerging C/N/S Cycling to Simultaneously Remove Dissolved Methane, Ammonium, and Sulfide from Synthetic Mainstream Anaerobic Effluent

Anaerobic wastewater treatment facilitates the recovery of organics in the form of biogas; however, the effluent often contains dissolved methane and sulfide. Dissolved methane, a potent greenhouse gas, can be readily emitted into the atmosphere, while sulfide is a toxic compound that may adversely affect the activity of other functional microbial populations. In this study, we demonstrated a new technology coupling Partial Nitritation, Anammox, Methane, and Sulfide-dependent nitrite/nitrate reduction (PNAMS) in a single membrane aerated biofilm reactor (MABR). The long-term results demonstrated that the PNAMS system achieved high-level (∼90%) nitrogen removal, nearly complete dissolved methane and sulfide removal from wastewater mimicking anaerobically treated domestic wastewater. 16S rRNA gene amplicon sequencing revealed that ammonia-oxidizing archaea (0.1–0.4%), nitrite-oxidizing bacteria (0.4–0.7%), anammox bacteria (0.1–0.2%), nitrate/nitrite-dependent anaerobic methane oxidation microorganisms (13.6–21.8%), aerobic methanotrophs (0.3–1.9%), and nitrate-reducing sulfide-oxidizing bacteria (0.1–0.3%) coexisted in the system, with their activities further confirmed by in situ batch tests. The results of this study were expected to provide a solution for the treatment of anaerobically treated domestic wastewater and also offer a model that connects C/N/S bioprocesses in engineering systems.