Table 1 - Experimental conditions with limitation and inhibition types for the four CFBRs
Condition

Reactor
1
2

3

4

Imposed conditions
Influent
in the bulk liquid
DO (mg/L) pH
TAN (mg/L)
0-200
6.5
7
60
Minimal limitation and inhibition
0-60
6.5
61-160
3.8
7
60
DO limitation
161-200
2.5
0-60
6.5
7
60
FA* and FNA**
Inhibition potential
61-200
7.6
8
150
Days

0-60

6.5

7

60

61-160
161-200

3.8
2.5

8

150

DO limitation
and FA* and FNA**
inhibition potential

* 0.6 mgFA/L is included in 60 mgTAN/L at pH 7 and 30  C , while 15 mgFA/L is in 150
mgTAN/L at pH 8 and 30  C .
** FNA inhibition is expected inside the biofilm. In case all TAN is converted to nitrite,
0.04 mgFNA/L is included in 60 mg/L of total nitrite nitrogen (TNiN) at pH 7 and 30℃,
while 0.4 mgFNA/L is included at pH 6.

Table 2 - Parameter values for simulations with the MSNBM
Kinetic parameter and Reactor operation
parameter
Df,

Value

Diffusion coefficient of biofilm (cm2/day) 1.6I, 1.5II, 1.5III, 1.7IV and 1.0V

KDO
KI,FA
KI,FNA

Diffusion coefficient of liquid-film
(cm2/day)
Yield coefficient (mgVS/mgS)
Maximum specific substrate utilization rate
(mgS/mgVS․day)
Half-maximum-rate concentration of
substrate (mgS/L)
Half rate concentration of oxygen (mgS/L)
Inhibition concentration (mgFA/L)
Inhibition concentration (mgFNA/L)

Keq

Acid/base equilibrium constant

B

Endogenous-decay coefficient (day-1)

0.51 0.682
101
0.52
0.751
0.12
NH4+ = 5.75*10-10
HNO2 = 5.13*10-4
HNO3 = 21.9
H2CO3 = 10-6.3
HCO3- = 10-10.3
H2O = 10-14
0.15

fd

Biodegradable fraction from decay

0.8

bdet
pHopt
W
Xf

Biofilm detachment rate (day-1)
Optimal pH
pH range of nitrifying bacteria
Total biofilm density (mgVS/cm3)

D
Y

q̂
KS

0
f

L

Initial length of biofilm (cm)

Reference
Picioreanu et al.
(1997)

1.25 times Df
0.331

0.0832

4.151

17.302

2.531

5.552

Rittmann and
McCarty (2001)

Park and Bae
(2009)

Flora et al. (1999)
Snoeyink and
Jenkins (1980)

Rittmann and
McCarty (2001)

0.06
1

7.72
2.42

8.4
3.21

Park et al. (2007)

18
0.0001

L
Length of liquid-film interface (cm)
0.007
This study
3
Q
Flow rate (cm /day)
2000
V
Reactor volume (cm3)
1000
2
A
biofilm surface area (cm )
750
I: TAN, II: TNiN, III: TNaN, IV: Oxygen, V: Total inorganic carbon (TIC), 1: AOB, 2: NOB

Table 3 - Experimental biofilm mass and density in each CFBR
Biofilm depth
Total VS
Total biofilm
(mg)
volume (cm3)I
(㎛)
Reactor 1
Reactor 2
Reactor 3
Reactor 4
Average

220
176
513
587

302
264
894
1660
Reactor 1 – 3

16.5
13.2
38.5
44.0

Biofilm density
(mg/cm3)II
18
20
23
38
20

Reactor 1 – 4
25
2
I. Total biofilm volume = biofilm depth/10000 (cm) × 750 (cm , biofilm surface area)
II. Biofilm density = Total VS / I