2011 International Conference on Alternative Energy in Developing Countries and Emerging Economies
- 96 -
(a)
(b)
Fig. 3
.
Time course of H
2
(Fig. 3 a) and CH
4
content (Fig. 3b) from the
bioreactor that contained base pretreated bacteria.
TABLE 2
C
HARACTERISTICS OF BREWERY WASTEWATER
U
SED IN THE EXPERIMENTS
.
Items
Content
pH
6.3
COD (mg/l)
6000
Total PO
4
3-
(mg/l as P)
0.02
TKN (mg/l as N)
90
Conin and Lo (1998) [20] reported that brewery
wastewater has a low concentration of nutrients.
Shi et
al. (2010) [13] demonstrated that H
2
production by the
seed sludge (obtained from an upflow anaerobic sludge
blanket reactor treating citrate-producing wastewater)
that was pretreated by heat shock was most effective
when the brewery wastewater concentration was 6000
mg/l. However, in their study, nutrients, such as
NH
4
HCO
3
, K
2
HPO
4
.3H
2
O, FeCl
2
, CoCl
2
.6H
2
O, NiCl
2
.
6H
2
O and CuCl
2
.5H
2
O were added to the brewery
wastewater. Dong-Yeol Lee et al. (2009) [21] reported
that H
2
utilizing methanogens in a semi-continuous
reactor could not be activated when there was
continuous control at the pH of 5.5 and the seed sludge
had been thermally pretreated. In this study, pH was
not artificially controlled and the pH gradually increased
reaching its highest points at 6.3, 6.7 and 6.4 (at day 50)
for heat, acid and base pretreatment inocula,
respectively. It can be seen from the graphs (Figs 1b, 2b,
and 3b) that methane (CH
4
) was observed in small
amounts at the beginning. Then, CH
4
production
gradually increased and reached nearly 80% (on
average) at day 50. The results show that although the
heat, acid or base pretreatment methods were performed,
methane producing bacteria (MPB) originating from a
brewery wastewater treatment could not be completely
suppressed. Moreover, MPB could be recovered if there
was sufficient time to promote cell growth. This is vital
when attempting to recover reactors for methanogenesis.
From this study, a period of approximately 30-50 days
was required for recovery of acid, base and heat treated
MPB. This is indicated by the higher levels of methane
that would be required for effective CH
4
production
(Figs 1b, 2b, and 3b).
For the choloroform as well as freezing and thawing
pretreatment methods, pretreated bacteria could not
produce H
2
even when the substrate was glucose-based
substrate rich with nutrients (Figs 4a and 5a) while CH
4
in the produced biogas was detected at significant levels
from the beginning of fermentation (Figs 4b and 5b).
This indicated that the H
2
utilizing methanogens from
the brewery wastewater treatment plant had not been
eliminated or suppressed by chloroform (2% by volume)
and freezing (at -20
0
C).
H
2
utilizing methanogens
originating from the brewery wastewater treatment plant
could tolerate the toxic
substance and the uncommon
(freezing) condition. Sinbuathong et al. (2009) [22]
reported that bacteria from a brewery digester sludge
were found to be the most appropriate culture of all from
their study for the treatment of wastewater with toxic
substances. The pH in the reactor was quite stable at
6.6 - 6.7 during the bioreaction time (from day 0- 50) for
both reactors. The results from this study implied that
chloroform caused a higher adverse effect to MPB as
compared with the freezing treatment method. When the
system was fed with the brewery wastewater, the reactor
that contained chloroform pretreated bacteria gave
approximately 50% of CH
4
(Fig. 4 b) while the reactor
that contained freezing pretreated bacteria gave a higher
content of CH
4
, showing 60% on average (Fig 5 b).
(a)
0
20
40
60
80
100
0 10 20 30 40 50 60
Time (days)
H
2
(%)
Glucose-based substrate
Brewery wastewater
0
20
40
60
80
100
0 10 20 30 40 50 60
Time (days)
CH
4
(%)
Glucose-based substrate
Brewery wastewater
