N2O production in a single stage nitritation/anammox MBBR process

10
8
DO concentration, pH & temperature
35
28
DO (mg/l), pH
6
4
21
14
Temp °C
DO (mg/l)
pH
Temperature (°C)
2
7
0
0
14/09/09
19/09/09
24/09/09
29/09/09
Date
04/10/09
09/10/09
14/10/09
19/10/09
350
Concentrations of influent and effluent total inorganic nitrogen
Total inorganic nitrogen (mg/l)
300
250
200
150
100
50
0
Σ TIN in (mg/l)
Σ TIN out (mg/l)
14/09/09
19/09/09
24/09/09
29/09/09
Date
04/10/09
09/10/09
14/10/09
19/10/09
Removal rate (gN/m²d)
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Removal rate (gN/m²d) & % reduction of incomming nitrogen
90
80
70
60
50
40
30
20
10
0
% reduction
Removal rate
(gN/m2d)
% reduction
14/09/09
19/09/09
24/09/09
29/09/09
Date
04/10/09
09/10/09
14/10/09
19/10/09
Figure 14. Illustration of how the process performance changes with changed operation mode, The
top graph illustrates DO during the aerobe phase, pH and temperature. The second graph shows
total concentration of inorganic nitrogen in influent feed and effluent water. The third graph
shows the removal rate gN/m 2 d and the reduced nitrogen in %.
4.3 N2O emissions from partial nitritation/anammox MBBR
The microsensor measured the N2O in the water phase during different operation modes
and aeration rates of the MBBR. The actual N2O production was not measured since N2O
left the water phase continuously through stripping and or by diffusion. However an
estimation of the N2O production was obtained by measuring the accumulation of the
N2O directly after the airflow is turned off assuming the N2O diffusion from water to air
is negligible. If corrections for the N2O leaving the reactor with the effluent water is
33