M
ATERIALS AND
M
ETHOD
A. Substrates and seed inoculum
Thai seafood cannery wastewater (TSCW) and
glycerol waste (GW) were collected from Kuang Pei San
Food Products Public Co., Ltd. in Muang Trang district
(Trang Thailand) and biodiesel plant at Prince of
Songkhla University in Hatyai district (Songkhla,
Thailand).
Wolffia arrhiza
(WA) was obtained from local
villager at Pannanikhom district (Sakonnakhon,
Thailand). The anaerobic seed was collected from
wastewater treatment plant of the Kiang Huat Sea Gull
Trading Frozen Food Public Company Limited (KST in
Hat Yai district (Songkhla, Thailand). The substrate and
seed stored at 4
o
C and put aside at room temperature
before used in the experiment. The main chemical
characterizations of substrate tested in this study are
shown in Table 1.
TABLE
I
CHEMICAL CHARACTERIZATION OF SUBSTRATES USED IN
THE EXPERIMENTS
Parameter
TSCW
GW
WA
pH
6.3
8.8
10.4
COD(mg/L)
10,400
1,760,000
ND
VFA(mg/L)
2,230
6,650
1,000
ALK(mg/L)
2,560
35,050
1,050
TN(mg/L)
870
1,670
1,010
TP(mg/L)
53.6
71,500
6,600
TS(g/L)
9.37
619
29.80
VS(g/L)
7.76
507
26.73
Protein(g/L)
7.42
1.28
179.10
Carbohydrate(g/L)
0.91
945
382
Lipids(g/L)
0.13
83.76
3.40
COD/N ratio
12
1054
ND
C/N ratio
1.05
566
378
*ND=Not determine
B. Bio-methane potential test
All experiment were conducted with 5 conditions were
TSCW alone, TSCW (99%)+GW(1%), TSCW
(96%)+GW
(1%)+WA
(5%),TSCW
(89%)+GW
(1%)+WA (10%) and TSCW(84%) +GW(1%)
+WA(15%). The bio-methane potential test was operated
in serum bottle size 1,000 ml with working volume 900
ml. The experiment was performed during 64 days and
under mesophilic (37
o
C) conditions. The initial seed used
in bio-methane potential test was 125 ml in all tests. The
biogas produced was collected by water displacement
method. The reactors were fitted with rubber stoppers and
sealed with aluminum caps. The
biogas volume and
composition were measured and recorded during the
experiment. This experiment was conducted in
period of 64 day.
C. Methane production in UASB reactor
The UASB reactor with a total volume 2.7 L and
working volume was 2.58 L. The experiments were
conducted under mesophilic (37
o
C) conditions and using
the initial seed 322.5 ml(125ml/L). The experimental
conditions are the best of the bio-methane potential test
and studied the effect of organic loading rate (OLR) on
the performance of biogas production by OLR studied
were 2, 4 and finally to 6 g COD/L.day at HRT 14, 7 and
5 day. The total treatment time 82 day. The composition
and volume of biogas produced were monitored during
the experiments, as were the level of pH, VFA/alkalinity
ratio and concentration of COD, volatile fatty acid
(VFA), Alkalinity for treatment performance.
C. Analytical methods
pH was measured using a pH meter model Sartorius
Docu. Chemical oxygen demand(COD) using closed
reflux method, total solid(VS), volatile suspended
solid(VSS), total nitrogen(TN), total phosphorus(TP),
volatile fatty acid, alkalinity, protein, carbohydrate and
fat and total ammonia nitrogen (TAN) were analyzed
using standard method for the examination of water and
wastewater [8]. The biogas volume and composition were
measured by displacement of water and analyzed by gas
chromatography (GC-8A Shimadzu) equipped with
thermal conductivity detector and filled with 2.0 m
packed column(Shin-Carbon ST 100/120 Restex) [9].
The synergistic effect was calculated using the methane
production from the best condition in bio-methane
potential test, compared with the methane production of
pure TSCW, GW(%) and WA(%) alone [10].
D. Substrate removal kinetic method
Monod model
For an UASB reactor without biomass recycle, the rate
of change of biomass and substrate concentration can be
expressed as Eqs. (1) and (2):
-
-
i
e
d
QX QX
dX
X K X
dt
V V
(1)
-
i
e
QS QS
dS
X
dt
V V Y
(2)
The ratio of the total biomass in the UASB reactor to
biomass wasted per given time represents mean cell-
residence time (
C
) and it can be calculated from Eq.
(3):
C
e
VX
QX
(3)
The correlation between the specific growth rate
(
max
) and the rate limiting substrate concentration can
be expressed by the Monod Eq. (4):
max
e
s
e
S
K S
(4)
If it is assumed that the concentration of biomass in the
influent can be neglected at steady-state condition (dX/dt
= 0 and –dS/dt = 0) and the HRT (
H
) is defined as the
volume of the reactor divided by the flow rate of the
influent, following equations can be obtained by
substituting Eqs. (3) - (4) into Eqs. (1) and (2):
1
d
c
K
(5)
2013 International Conference on Alternative Energy in Developing Countries and Emerging Economies
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