Design of denitrifying plants
280
240
200
160
120
80
40
• COD
+ COD(filt.)
9-11 13-1517-19 21-23 01-03 05-07 09-11 13-1517-19 21-23 01-03 05-07
Hour
Fig 7.26 COD-variations over 2 days /16/.
264
3
Xs,H = 0.80 kg/m
3
Xs,A = 0.20 kg/m
X1
= 2.80 kg/m 3
Tlg
= 0.5
Determination of process constants. The saturation constants for oxygen have by
batch experiments been determined for both nitrifying and denitrifying bacteria, and
the following values have been found:
K
-o5 1 3
S,02,A
- . g m
Ks,02(N03) = o.023 g!m 3
By model calculations, four constants were changed in relation to the standard values.
These are (the standard values are stated in brackets):
bH
= 1.5 d- 1
Ks,COD = 2 g COD/m 3
3
Ks.o2.H = 0.5 g 02/m
3
Ks.o2.A = 0.5 g 02/m
(0.62 d- 1 )
(2.5 g COD/m 3 )
(0.2 g 02/m 3 )
(0.4 g 02/m 3 )
The process explanation of these changes is as follows:
-The higher value for decay, bH. is assumed to be due to the special characteristics of
the influent water in the form of a low content of suspended solids. In this way another