N2O production in a single stage nitritation/anammox MBBR process

With the considerations; (i) that there is no N2O gas in the influent medium, (ii) the
reactor volume is constant and (iii) Qin and Qout are equal the mass balance for the
system can be described by:
eq.(3.3)
: ( )
eq.(3.4)
: 0 ( )
To get the consumption and production rates equation 3 and 4 are rewritten:
eq.(3.5)
:
( )
eq.(3.6)
:
( )
rN in the first equation is describing the consumption rate of the influent nitrogen, if
there were no N2O or any other gaseous production in the system this term would
entirely correspond to the production of N2 gas leaving the system. Here it is assumed
that all removed inorganic nitrogen is leaving the system in gaseous form as N2 or N2O.
The accumulation term that would correspond to assimilation in equation 3 is neglected.
Calculation example (091007)
Used parameters to calculate the consumption (rN) and production (rN2O ) rates are
shown in Table B1.
Table B1. Calculation parameters used to caluclate r N and r N2O.
Parameter value unit
Q 0.540 l /h
V 7.5 l
cinN 273.904∙10 -3 g/ l
coutN 97.593∙10 -3 g/l
c N2O t1 2.82414∙10 -6 mol/l
c N2O t2 2.97601∙10 -6 mol/l
0.1519∙10 -6 mol/lmin
0.540 · (273.904 · 10 97.593 · 10 )
0.2116 · 10
7.5 · 60
0.540 · (2.97601 · 10 )
0.1519 · 10 0.1555 · 10
7.5 · 60
g/lmin
mol/lmin
68