Mdodeling a nitrite-dependent anaerobic methane oxidation process: Parameters identification and model evaluation

Nitrite-dependent anaerobic methane oxidation (n-damo) is a recently discovered process that is intermediated by n-damo bacteria that oxidize methane with nitrite to generate nitrogen gas. In this work, a kinetic model based on Monod type kinetics and diffusion-reaction model was developed to describe the bioprocess. Some key kinetic parameters needed in the model were obtained from a series of batch activity tests and a sequencing batch reactor (SBR) operation over 100 days. The growth rate, decay rate, methane affinity constant, nitrite affinity constant and inhibition constant were 0.0277 ± 0.0022 d−1, 0.00216 ± 0.00010 d−1, 0.092 ± 0.005 mmol L−1, 0.91 ± 0.09 mmol L−1 and 4.1 ± 0.5 mmol L−1 for n-damo bacteria at 30 °C, respectively. The results showed that the model could simulate actual performance of the SBR in the first 76 days, that methane was not a limiting factor at atmospheric pressure for its high affinity, and that the optimum nitrite concentration was 1.92 mmol L−1.