N2O production in a single stage nitritation/anammox MBBR process

N₂O µmol/l
12
10
8
6
4
2
0
0 100 200 300 400 500
N₂O (µmol/l)
y = -0.0132x + 10.59
Time (min)
Figure 23. N 2O decrease in the water phase due to diffusion during mechanical mixing.
When the system was aerated dissolved N2O was stripped out of the water phase at a
much higher speed compared to the diffusion rate, see Figure 24-Figure 26. However the
stripping rate did not change much with the different aeration rates. When the reactor
was aerated with an airflow corresponding to 1.2 l/min, dissolved N2O left the water
phase at a rate of ~0.55 µM/min, if linearly approximated, see Figure 24. The linear that
is drawn in Figure 24 shows that a linearization is not a good approximations of how
N2O was stripped out of the water phase. As the stripping rate decreased with
decreasing N2O concentration a potential curve fitting might be a better option which is
also shown in Figure 24.
14
Aeration 1.6 (l/min) with carriers
N₂O (µmo/l)
12
10
8
6
4
2
0
0 5 10 15 20 25
Time (min)
N2O (µmol/l)
y = -0.6482x + 10.193
y = 12.95e -0.143x
Figure 24. Stripping of N 2O from the water phase during aeration with an airflow of 1.2 l/min.
As the aeration rate was increased to 1.6 l/min the linear stripping rate increased to
~0.65 µM/min, see Figure 25.
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