Μελέτης της επίδρασης προκατεργασίας θερμού νερού σε διατροφικά απορρίμματα καθώς και του ενζυμικού φορτίου στην τελική παραγωγή βιοαιθανόλης μέσω εφαρμογής της μεθόδου NSSF
(EL)
The excessive use of fossil fuels makes it imperative to seek for alternative sources of
energy and fuels. The production of biofuels forms a reliable solution for the
confortation of the problem. Considering that the conventional raw materials
used for
the production of biofuels are also a food source and their cultivation requires
extended land areas, the interest for biofuels production turns to the exploitation of
biowastes such as food wastes. In the present thesis, we have studied the produ
ction
of bioethanol from food wastes and in particular the effect of the pretreatment in the
process. Initially, we examined the effect of enzyme loading (Cellic
® CTec2)
during
enzymatic hydrolysis of food
-
waste as well as in bioethanol production. Food w
aste
samples were pretreated with liquid hot water in the presence of H
2
SO
4
(100
o
C , 3 h ,
3 % (w/w) concentration of H
2
SO
4
) and hydrolysed at enzyme loading of 10,20,40 and
60 FPU/ g dry FW. The results indicated that hydrolysis is favored at high enzyme
loadings. Maximum glucose concentration
55.67 g/L
and maximum reducing sugars
concentration
98 g/L
were achieved using
60 FPU/ g dry FW
. Then, a
non isothermal
simultaneous saccharification and fermentation (NSSF) process operating in batch
mode was appl
ied. Samples were pretreated with
liquid hot water
at two different
conditions, a mild one (t=1 h,
Τ
=80
o
C, C
H2SO4
=1%, w/w)
and an extreme one (t=3 h,
Τ
=100
o
C, C
H2SO4
=3%, w/w). The pretreated material was prehydrolyzed using initially
a commercial glucoamylase preparation (Spirizyme
60 U/g starch FW,
Τ
=65
ο
C, 30
min) followed by the addition of
Cellic
® CTec2 at enzyme loading of 5, 10, 20, 40, 60
FPU/g cellulose FW
for 6 h at 50
o
C. The maximum ethanol production was achieved
via the mild pretreatment for the loading of 60 FPU/g cellulose FW and found equal
to
24.89 g/L
. Despite that, and taking under consideration the
production
cost,
40 FPU
was considered as the opt
imum loading for
the
process. Finally, we examined the
combined effect of temperature, duration of pretreatment and concentration of
H
2
SO
4
solution in the yield of
the
process.
A
Box
-
Benkhen experimental design with 3
independent values and 13 different
combinations of temperature, duration and
concentration
, was applied
.
A batch nonisothermal simultaneous saccharification and
fermentation (NSSF) process was applied
as described above
.
M
aximum
ethanol
concentration
29.96 g/L
was achieved
when FW was pretr
eated at
90
o
C, 1 h and 1%
H
2
SO
4
concentration,
which is equivalent to a yield of
83.06
%
of theoretical. During
that particular process, starch was removed at a percentage of
90.34 %
and cellulose
at
58.4 %
, which was the highest percentage achieved
(EN)
Εθνικό Μετσόβιο Πολυτεχνείο
