Production and decomposition of nitrous oxide during biological denitrification

Abstract

Nitrate (NO 3 ) was reduced with methanol (MeOH) over denitrification‐filter sludge in a closed reactor. The initial reaction product was nitrous oxide (N 2 O). It accumulated to a maximum (N 2 O max ) and was then rapidly reduced to nitrogen (N 2 ). At the time of maximum accumulation ( t max ), 50 to 80% of the nitrate‐nitrogen reduced was in the form of N 2 O. These results led to a higher estimate of N 2 O emission from biological denitrification than previously considered. The results also suggest the concept of a multistage anoxic reactor in which nitrate can be reduced to N 2 with minimal emission of N 2 O. The design would provide for retention of N 2 O in the upstream stages and reduction of N 2 O downstream.