Kinetic study on anaerobic oxidation of methane coupled to denitrification

Monod kinetic parameters provide information required for kinetic analysis of anaerobic oxidation of methane coupled to denitrification (AOM-D). This information is critical for engineering AOM-D processes in wastewater treatment facilities. We first experimentally determined Monod kinetic parameters for an AOM-D enriched culture and obtained the following values: maximum specific growth rate (μ_max) 0.121/d, maximum substrate-utilization rate (q_max) 28.8 mmol CH₄/g cells-d, half maximum-rate substrate concentration (K_s) 83 μΜ CH₄, growth yield (Y) 4.76 g cells/mol CH₄, decay coefficient (b) 0.031/d, and threshold substrate concentration (S_min) 28.8 μM CH₄. Clone library analysis of 16S rRNA and mcrA gene fragments suggested that AOM-D reactions might have occurred via the syntrophic interaction between denitrifying bacteria (e.g., Ignavibacterium, Acidovorax, and Pseudomonas spp.) and hydrogenotrophic methanogens (Methanobacterium spp.), supporting reverse methanogenesis-dependent AOM-D in our culture. High μ_max and q_max, and low K_s for the AOM-D enrichment imply that AOM-D could play a significant role in mitigating atmospheric methane efflux. In addition, these high kinetic features suggest that engineered AOM-D systems may provide a sustainable alternative to nitrogen removal in wastewater treatment.