Activated Sludge Treatment Plants
waters an estimate will often be sufficient for a calculation. For industrial wastewaters and atypical municipal wastewaters, detailed analyses of the water should
be carried out.
In respect of the constants which are included in the programs, the same applies as
for the description of the wastewater. Estimates can be made for municipal wastewater, see for example Table 4.8, whereas for other types of wastewater tests should
be made. Do not forget to take the relation between the constants into consideration.
For example, it is necessary to use high JlmaJCvalues to compensate, in terms of
calculations, for the 3 to 4 monod-terms which are often attached to the growth rates
in the models.
Constant
Unit
UCTASP /10/
P111 /7 I EFOR /8/ No.1 /2/
Stoichiometric constants
YA
gCOD/gN
0.15
0.24
0.24
0.24
YH
gCOD/gCOD
0.67
0.57
0.67
0.67
fi
-
0.08
0.10
0.08
0.08
fB,N
gN/gCOD
0.068
0.07
0.086
0.086
fxi,N
gN/gCOD
0.068
0.06
0.02
0.06
Kinetic constants
J.lmax,H
d-1
3.2
4.0
6.0
6.0
J.lmax,A
d-1
0.45
1.0
0.8
0.8
Ks,coo
gCOD/m 3
5
20
2.5
20
Ks.o2
g02/m 3
0.002
0.25
0.2
0.2
Ks,N03
gN03-N/m 3
0.1
0.5
0.5
0.5
Ks,NH4,A
gNH!-N/m 3
0.002
0.5
0.4
0.4
Ks,o2,A
g02/m 3
1.0
0.8
1.0
1.0
bH
d-1
0.62
0.5
0.62
0.62
bA
d-1
0.04
0.15
0.15
llg
-
0.33
0.8
0.8
0.8
llh
-
0.35
0.35
0.4
kh 1 )
gCOD/(gCOD· d)
1.35
1.5
5.0
3.0
Kx
gCOD/gCOD
0.027
0.02
0.03
0.03
I) The constant is linked to different rate expressions in the models .
Table 4.8
Examples of standard constant sets used in computer models for activated sludge processes (20°C)
For ordinary activated sludge plants it will especially be the oxygen conditions
where the models make it possible to calculate variations in the oxygen consumption. Variations, as those shown in Fig 4.12, can only be calculated by using a model.
Such calculations are an important tool in connection with the design of plants and
the analysis of the operation of the plant.
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