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Ethanol Production Using Organic Waste
Daewon Pak, Jun Cheol Lee, Jae Hyung Kim
Graduate School of Energy and EnvironmentSeoul National University of Technology
Research Background
Bioethanol in Korea
3 - 5% ethanol blends 3 - 5% ethanol blends
High oil priceHigh oil price
Reduce global warming gasReduce global warming gas
3 - 5% ethanol blends with gasoline (E3 and E5)
3 - 5% ethanol blends with gasoline (E3 and E5)
Renewable energy(5% of total energy in 2011)
Renewable energy(5% of total energy in 2011)
Low bioenergy share(5.3% of renewable energy
in ‘08)
Low bioenergy share(5.3% of renewable energy
in ‘08)
Research Background
Organic waste produced in Korea
Food waste production Food waste production (ton/day)
Separate collection (%)
Research Background
Food waste produced in Korea
ton/day
14,000
13,00013,000
12,000
11,000
10,000
2001 2002 2003 2004 2005 2006
Composition
C 46.1 ~ 48.1 %
H 6.8 ~ 7.2 %
pH 4.2~4.5
Ash 5 %
Research Background
Composition of kitchen refuse
H 6.8 ~ 7.2 %
O 32.4 ~ 36.7 %
N 3.5 ~ 4.1 %
Cl 1.9 ~ 2.2 %
Moisture content
72.99 ~ 84.96 %
Crude Protein(%) 20~25 %
Crude Fiber(%) 8~20%
Crude Lipid(%) 5~15 %
Total Sugar(%) 47~54 %
weight percentage based on dry food wastes
Research Background
Food waste as alternative substrate for ethanol production
High sugar content
High potential of ethanol production
In abundant supply (about 5 million ton per year)
Potentially promising bioresource
High potential of ethanol production
High concentration of salt ( 1.9 2.2 %)
Does not lead to resource conflict (insufficient food supply)
Materials and Methods
pHSalinity
(%)Alkalinity(mg/L)
Volatile solid(g/L)
Total solid(g/L)
SCOD(g/L)
TCOD(g/L)
4.5 – 4.8 1.5-1.8 0.1 – 0.3 130 - 138 163 - 190 62 - 98 150 - 180
Substrate
Enzyme and microorganism
Microorganisms Saccharomyces
EnzymeCarbohydrase (Asperrillus aculeatus, Viscozyme L)Glucoamylase (Asperrillus niger, Spirizyme plus FG)
Materials and Methods
Experimental set-up
Enzymatic saccharification Enzymatic saccharification ðanol fermentation
Enzymatic saccharification of food waste using carbohydrase
control
Food wastes
Pre-treatment
Saccharification
Enzyme
Hexose
00 03 06 09 120
5
10
15
20
25
gluc
ose
conc
entr
atio
n (g
)
time (hr)
control 0.36g(about 28.8 FBGU) 1.8g(about 144 FBGU) 3.6g(about 288 FBGU) 18g(about 1440 FBGU) 36g(about 2880 FBGU)
Enzymatic saccharification of food waste using carbohydrase
DosageEnzyme Control 0.1% 0.5% 1.0% 5.0% 10.0%
Glucoamylase(Spirizyme)
0.003 0.241 0.314 0.384 0.414 0.436(Spirizyme)
0.003 0.241 0.314 0.384 0.414 0.436
Carbohydrase (Viscozyme L)
0.003 0.379 0.481 0.495 0.522 0.627
Unit: g glucose/g total solids
Effect of salt concentration on S. cerevisiae for ethanol fermentation
60
80
Eth
anol
con
cent
ratio
n (m
g/L)
control NaCl 1% NaCl 2% NaCl 3%
00 04 09 14 19 240
20
40
Eth
anol
con
cent
ratio
n (m
g/L)
Time (hr)
NaCl 3% NaCl 5% NaCl 10% NaCl 15%
Comparison between S. cerevisiae and T. Ethanolics for ethanol production
4
6
8
10
2
3
4
5
glu
cose
(g)
glucose
ethanol
Eth
anol
pro
duct
ion(
g)
(Mesophillic, yeast) S. cerevisiae T. Ethanolicus (Thermophillic, bacteria)
4
6
8
10
2
3
4
5
sucr
ose
(g)
sucrose ethanol
Eth
anol
pro
duct
ion
(g)
00 03 06 09 12 15 18 21 240
2
4
0
1
2
glu
cose
(g)
Time (hr)E
than
ol p
rodu
ctio
n(g)
Ethanol g / g-glucose
S. cerevisiae 0.51
T. ethanolicus 0.37
00 02040608 10121416 18202224 26 2830 32 343638 40 424446 48 5052540
2
4
0
1
2sucr
ose
(g)
Time (hr)
Eth
anol
pro
duct
ion
(g)
Separate enzymatic saccharification and ethanol fermentation
Saccharification
Enzyme
Food wastes Ethanol Fermentation
Microbes
Ethanol
00 12 24 36 480.0
0.2
0.4
0.6
0.8
1.0
0.0
0.2
0.4
0.6
0.8
1.0
glucose
inoculation
gluc
ose
(g/ g
TS)
time (hr)
ethanol
eth
anol
(g/
g T
S)
0.8
1.0
0.8
1.0
glucose
gluc
ose
(g/ g
TS)
ethanol
Simultaneous enzymatic saccharification and ethanol fermentation
Enzyme Microbes
00 12 240.0
0.2
0.4
0.6
0.0
0.2
0.4
0.6
gluc
ose
(g/ g
TS)
time (hr)
eth
anol
(g/g
TS)
Saccharification &Ethanol Fermentation
Food wastes
Ethanol
Comparison SHF and SSF
Ethanol production
SHF 0.43 g ethanol /g TS
SSF 0.31 g ethanol /g TS
Conclusions
• Food waste is difficult to be utilized by ethanol producing microorganism. Pretreatment using two different enzymes, carbohydrase (Aspergillus aculeatus, Viscozyme L) and glucoamylase(Aspergillus niger, Spirizyme Plus FG) were tested for saccharification of food waste. Carbohydrase was able to hydrolyze and produce glucose at 0.63 g glucose/g total solid which was higher than glucoamylase.
• The amount of carbohydrase added to food waste determines the rate of saccharification. As the amount of enzyme addition increased, the rate of saccharification was increased. At higher than amount of enzyme addition increased, the rate of saccharification was increased. At higher than 1440 FBG of enzyme activity, the saccharification rate was not increased further.
• In the separate enzymatic hydrolysis and ethanol fermentation, ethanol was produced at 0.43 g ethanol /g TS. For simultaneous saccharification and ethanol fermentation, glucose concentration increased rapidly and reached to a maximum which was less than the level obtained from the separate saccharification and ethanol fermentation. Ethanol was produced at 0.31 g ethanol/g TS which was less than the separate enzymatic hydrolysis and ethanol fermentation.