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Biofilm characterization and operation performance in a
single stage partial nitritation/anammox process with a function carrier
1Graduate School of Environmental Studies, Tohoku University, Miyagi 980 -8579, Japan.2Department of Civil and Environmental Engineering, Tohoku University, Miyagi 980 -8579, Japan
Yunzhi QIAN1, Yan GUO2, Junhao SHEN1 & Yu-You LI1,2*
The 8 th International Symposium on Water Environment Systems----- with Perspective of Global Safety (Nov. 13th ~ 14 th , 2020)
1. Introduction1.3 Objectives
Problem: Sludge washout and coexistence of AOB and anammox bacteria
Proposal: Adding carrier Double biofilm structure
High amount of biomass & Avoid sludge washout
SPNA reactor Carrier
The objectives of this study are to:
1.2 Problem and proposal 1.3 Objectives
study the formation characterization of biofilms;
determine the high activity maintenance strategy of
biofilm under long-term operation.
The outcomes of this study promise to include valuable
insight into SPNA process operation, and serve to the
further expansion of SPNA process application in industrial
applications
2. Material & Methods
Figure 1 Photo of carriers.
Table 1 Characteristics of carrier
2.1. Carrier 2.2. Apparatus
Figure 2 Schematic diagram of ALR-SPNA: ① substrate tank; ②influent pump; ③ air lift single SPNA reactor; ④ air pump; ⑤heater; ⑥ carrier
2.3. Operation conditions
3. Results & Discussion
3.1 Long-termoperation performance 3.2. Sludge characteristics
0
10
20
30
0
3
6
9
12
15
0.0
0.2
0.4
0.6
0.8
1.0
1.2
(d)
(c)
(b)
No sludge discharge Inregular
sludge discharge
Ⅷ
ML
SS
(g/L
)
MLSS-Suspended
MLSS-Biofilm
MLSS-Total Mechanical stirring
treatment
No sludge discharge
(a)
ML
VS
S (
g/L
)
MLVSS-Suspended
MLVSS-Biofilm
MLVSS-Total
ML
VS
S/M
LS
S r
atio
Ratio -Biofilm
Ratio -Suspended
Ratio -Total
0 50 100 150 200 250 300 350 400
0
20
40
60
80
100 SV30 SVI
Operation time (d)
SV
30
(%
)
Phase
0
100
200
300
400
500
SV
I (m
L/g
)
Ⅰ Ⅱ Ⅲ Ⅳ Ⅴ Ⅵ Ⅶ
The SPNA process was successfully operated
under NLR of 0.9 gN/L/d and NRE of 84%.
△NO3--N/△Nr is 0.10±0.01 during thestable
operation of SPNA system.
In phase 1, with NiRR/NARR ratios above 0.65,
the anammox reaction was the rate-limiting step
of total nitrogen removal.
Figure 3 The long-term operation performance of SPNA
systemFigure 3 Sludge characteristics of ALR-SPNA system.
The MLVSS concentration of the biofilm
during stable operation of SPNA is 4±0.5g/L.
After mechanical stirring treatment in phase
7, MLVSS concentration in the biofilm
recovered to 4.0g/L within one month.
3. Results & Discussion
4. Conclusions
3.3. Biofilm characteristics
Figure 5 Photo of biofilm. (a) day 84; (b)day 156; (c) day 214; (d)day 310; (e) day 360.
The formation of biofilm can be divided into four stages: the biofilm formation period (a and b),
the biofilm mature period (c), the biofilm aging period (d) and the biofilm reactivation period (e).
The cavity formed by N2 accumulation is the main factor causing the decline of biofilm activity.
Figure 6 SEM observation of biofilm. (a) blank; (b)biofilm formation period ; (c) biofilm mature period; (d)biofilm aging
period .
The pores on the surface of carrier are
conducive to the adhesion of anammox and
the rapid formation of biofilm
Sludge in the mature period of the biofilm
is aggregated as granules.
Ca and P concentrations increased from
biofilm mature period to biofilm aging period
Figure 7 EDX analysis of the biofilm. (a)biofilm mature period; (b) biofilm aging period.
The biofilm in low activity has the lowest VSS/SS ratio and anammox bacterial activity.
Figure 8 Analysis of the biofilm. (a) biofilm in aging period; (b) MLSS and MLVSS; (c) EPS; (d) SAA
Higher SAA of biofilm in high activity than biofilm.
The cavities generated by nitrogen gas and the accumulation of inorganic substances are the
main reasons for the decrease in NRE.
The SPN/A process was successfully operated under NLR of 0.9 gN/L/d and NRE of 84%.
Mechanical stirring can maintain the high activity of the biofilm.
0.00
0.05
0.10
0.15
0.20
0.25
SA
A (
gN
/gV
SS
/d)
SAA
Biofilm Suspended Biofilm in
high activity
Biofilm in
low activity0
2
4
6
8
10
12
14
16
Biofilm in
low activity
Biofilm in
high activity
Suspended
EP
S (
mg/g
VS
S)
PS
PN
Biofilm0
1
2
3
4
5
6
PN/PS
PN
/PS
0
2
4
6
8
10
12
ML
SS、
ML
VS
S (
g/L
)
MLVSS
MLSS
Biofilm Suspended Biofilm in
high activity
Biofilm in
low activity
0.0
0.2
0.4
0.6
0.8
MLVSS/MLSS
ML
VS
S/M
LS
S
High activity
Low activity
0.0
0.5
1.0
1.5
0.0
0.3
0.6
0.9
1.2
0.0
0.1
0.2
0.3
0.4
0.5
0
300
600
900
1200ⅥⅤⅣⅢⅡⅠ
NH4+-Ninf
NH4+-Neff
NO2--Neff
NO3--Neff
N i
n i
nfl
uen
t (m
g/L
)
Phase Ⅷ
0
100
200
300
400
500(a)
Ⅶ
N i
n e
fflu
ent
(mg
/L)
(b)
0
20
40
60
80
100 NRE
NRR
NR
E (
%)
0.0
0.2
0.4
0.6
0.8
1.0
(c)
NR
R (
gN
/L/d
)
(d)
NiR
R、
NaR
R、
NA
RR
(gN
/L/d
)
NiRR
NaRR
NARR
(e)
NiR
R/N
AR
R
NR
R/N
AR
R
NiRR/NARR
NRR/NARR
3-
0.11
3
0
20
40
60
80
100
(g)
(f)FA FNA FNA 10μg/L FA 5mg/L
FA
(m
g/L
)
0
5
10
15
FN
A (
μg
/L)
0 50 100 150 200 250 300 350 400
0.0
0.1
0.2
0.3
0.4
0.5
DO
AR
Operation time (Days)
DO
(mg
/L)
0.0
0.5
1.0
1.5
2.0
2.5
AR
(L/m
in)