2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
- 45 -
TABLE I
E
XPERIMENTAL DESIGNS
.
Set of
test
Exter
nal
load
(kΩ)
OLR
(gCO
D/l/d)
HR
T
(day
)
pH
Aerati
on
(ml/min
)
1.Effect
of
external
resistanc
e
1-30
6.0
1.04
6.6-
7.5
200
2. Effect
of OLR
6.0-
45.0
1.04
6.6-
7.5
200
3. Effect
of HRT
0.35
-
2.08
6.6-
7.5
200
D. Calculation
The electric current and power were calculated
as follow:
I
=
V/R
(1)
P
=
V
2
/R
(2)
where V is cell voltage (V), R is external
resistance (Ω).
Volumetric current or power was
determined by divided it with an anode
volume. The COD concentration, TS and VS were
measured using Standard method (APHA, AWA,
WPCF, 1995). A complete block design (CBD) and
Duncan test were used for statistical analysis.
III. R
ESULTS AND DISCUSSION
A. Start up and operation
After start up with diluted POME of 6.0 g/l for
a week, the open circuit voltage increased up to
0.88-0.91 V. It meant micro-organism was ready
activated in both anode and cathode parts.
B. Effect of external resistance on electricity
generation and COD removal efficiency
The effect of external resistance on electricity
generation of Thai microbial fuel cell was tested at
five resistances such as 1.0, 5.0, 10.0, 20.0 and
30.0
kΩ.
The neutral palm oil mill effluent of 6.0 g
COD/l was fed at HRT 1.04 day and aerated at 200
ml/min. The optimum condition was found at 10
kΩ which obtain highest COD removal of 94.13%
(Fig. 3B) and power density per volume of 11.59
mW/m
3
(Fig.3A)
Fig. 2. Effect of external resistance on electricity generation and
COD removal efficiency, the neutral palm oil mill effluent of 6.0
g COD/l was fed at HRT 1.04 day and aerated at 200 ml/min.
C. Effect of COD concentration on the performance
of Thai MFC
The experiment was conducted at various COD
concentrations of POME e.g.
6.0
,
15.0, 30.0
and
45.0
g COD/l
and closed circuit by
10 k
Ω (
selected
from
B
)
. The cell showed the maximum efficiency
at OLR 30.0 g COD/l/d that gained 0.370 V. at 10
kΩ or 15.21
mW/m
3
and achieved the highest COD
reduction of 90.23% (Fig. 3A)
D.Effect of HRT on the Thai MFC performance
The MFC was fed with neutral pH POME at
OLR of 30.0 g COD/l/d at three hydraulic retention
times (0.35, 1.04 and 2.08 day).It was aerated at
200 ml/min and connected circuit by 10 kΩ
resistant. The result revealed that HRT of 2.08 was
the optimum rate to reduce COD high up to 90.92%
(Fig. 3B). It indicated that longer HRT left bacteria
well degraded and enhanced organic matter
removal. However, the HRT of 1.04 presented
greater voltage (0.294 V) than of 2.08 (0.165 V)
and still had COD removal over 80% (Fig. 3B).
Therefore, the HRT of 1.04 was selected.
0
5
10
15
0
20
40
60
80
Volumetric Power (mW/m3)
A
b
b
c
b
a
b
0
20
40
60
80
100
% COD removal
External resistance (k
Ω
)
ขั
Ê
วลบ ขั
Ê
วบวก
B
anode
cathode
open
circuit
Volumetric current (A/m
3
)
