Nitrifying activity monitoring and kinetic parameters determination in a biofilm airlift reactor by respirometry

The applicability of batch respirometry, as a simple technique for monitoring off-line nitrifying activity and kinetic parameters, was evaluated using two sets of ammonia and nitrite concentrations. The O-2 uptake rate (OUR) profiles obtained from the assays were adjusted to a substrate inhibition model. The maximum specific ammonia-oxidizing biomass activity (r(Smax)) was 0.079 g N-NH4+ g VSS-1 d(-1) with a half saturation coefficient (K-S) of 11 mg N-NH4+ l(-1) and an inhibition coefficient (K-i) of 3300 mg N-NH4+ l(-1). Besides, the maximum specific value of nitrite-oxidizing activity was 0.082 g N-NO2- g VSS-1 d(-1) with a K-S of 4.1 mg N-NO2- l(-1) and K-i of 1400 mg N-NO2- l(-1).