Kinetic modelling of pseudomonas denitrificans growth and denitrification under aerobic, anoxic and transient operating conditions

The transient growth characteristics of Ps. denitrificans to changes from anoxic to aerobic conditions and vice-versa were studied and an appropriate mathematical model was developed. This kinetic model adequately describes the behavior of the denitrifying bacterium under strictly anoxic, strictly aerobic and transient conditions of growth. Dissolved oxygen exhibited an inhibitory effect on the activity of the enzymes associated with denitrification. Each step of the denitrification pathway was affected differently by dissolved oxygen concentration. Nitrate reduction was the least sensitive step, while reduction of N2O and/or NO was almost completely inhibited by dissolved oxygen. Very long lag phases were observed following an anoxic to aerobic shift, whereas denitrification was immediately initiated following an aerobic to anoxic shift.