Nitrous oxide production in completely autotrophic nitrogen removal biofilm process: a simulation study

The dissolved oxygen (DO) concentration is known to be one of the most important factors affecting nitrous oxide (NO) production, which might weaken the advantages of nitrogen removal in completely autotrophic nitrogen removal biofilm process. In this work, a mathematical model is applied to study the NO production in a biofilm reactor performing nitritation followed by anaerobic ammonium oxidation (Anammox) for nitrogen removal. The nitrifier denitrification pathway through utilization of nitrite as the terminal electron acceptor under oxygen limiting conditions is used to predict NO production. Simulations explicitly show that a large number of NO is produced under conditions of low DO concentration for high nitrogen removal. A low ammonium concentration