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 (mu(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 mu M CH4, growth yield (Y) 4.76 g cells/mol CH4, decay coefficient (b) 0.031/d, and threshold substrate concentration (S-min) 28.8 mu M 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 mu(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.