N2O production in a single stage nitritation/anammox MBBR process

The rN value is calculated with the mean in and effluent concentrations during one cycle/
measurement session. For the approximation of the total N2O production in the MBBR it
is assumed that the production corresponds to the initial value of rN2O seen when
aeration is turned off (Figure B2) and that this assumption is valid at all times.
12
N₂O (µmol/l),DO (mg/l)
10
8
6
4
2
N₂O
(µmol/l)
DO
(mg/l)
N₂O (µmol/l), DO (mg/l)
0
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
0 20 40 60 80
Time (min)
Initial N₂O production
2.82414
2.97601
20 22 24 26 28 30
N₂O
(µmol/l)
DO
(mg/l)
y = 0.1519x - 0.8207
Time (min)
Figure B2. The accumulation term in the production rate equation is obtained as the initial k-value
of the N 2O curve when N 2O starts to accumulate in the reactor. The lower part of the figure shows
an enlargement of the area.
The percentage of removed inorganic nitrogen emitted as N2O is finally obtained by:
· 2
· 100
where rN2O given in mole N2O/l min is converted to g N/l min by multiplying with 2MN,
the molar weight of N in g/mole. MN is multiplied by 2 since the molar ratio for produced
N2O-N to removed inorganic N is 2:1.
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